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CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of U.S. patent application Ser. No. 14/021,919, filed Sep. 9, 2013, which is a continuation of U.S. patent application Ser. No. 12/687,439, filed Jan. 14, 2010, which is a continuation of International Patent Application No. PCT/CN2008/071879, filed Aug. 5, 2008, The International Application claims priority to Chinese Patent Application No. 200710143608.X, filed Aug. 14, 2007. The afore-mentioned patent applications are hereby incorporated by reference in their entireties.
FIELD OF THE INVENTION
The present invention relates to network communication, and in particular, to a system, a method, a Base Station, and a Radio Network Controller (RNC) for one cell to cover multiple areas.
BACKGROUND
In the current communication system, one cell may cover multiple areas. Two solutions in the existing art regarding the one cell covering multiple areas are presented as below.
Solution 1: A Base Station and a repeater enable one cell to cover multiple areas, as shown in FIG. 1 and FIG. 2 .
In FIG. 1 , three areas, namely, area C, building A, and building B belong to the same cell. A local end 1 and a remote end 1 constitute a repeater, and a local end 2 and a remote end 2 constitute another repeater. Therefore, one Base Station and two repeaters accomplish coverage for three areas (A, B, and C) in a cell. Areas A, B, and C belong to one cell, and the cell corresponds to one Radio Frequency (RF) module in the Base Station. The remote end 1 includes an RF module, and the remote end 2 includes an RF module. Therefore, three RF modules are required for one cell to cover multiple areas in FIG. 1 .
In FIG. 2 , floors 1 - 10 and floors 11 - 20 belong to the same cell. A local end 1 and a remote end 1 constitute a repeater, and the repeater covers higher floors 11 - 20 . A local end 2 and a remote end 2 constitute another repeater, and this repeater covers lower floors 1 - 10 . Therefore, one Base Station and two repeaters accomplish coverage for two areas (higher-floor area, and lower-floor area) in a cell. The higher-floor area and the lower-floor area belong to one cell, and the cell corresponds to one RF module in the Base Station. The remote end 1 includes an RF module, and the remote end 2 includes an RF module. Therefore, three RF modules are required for one cell to cover multiple areas in FIG. 2 .
Solution 2: A Baseband Unit (BBU) and a Remote Radio Unit (RRU) enable one cell to cover multiple areas, as shown in FIG. 3 .
In FIG. 3 , lower floors 1 - 10 and higher floors 11 - 20 belong to the same cell. RRU 1 covers higher floors 11 - 20 , RRU 2 covers lower floors 1 - 10 , and RRU 1 and RRU 2 are connected with the BBU in the Base Station through a Digital Combiner and Divider unit. Therefore, two remote RF modules and a digital combiner and divider unit accomplish coverage for both the higher-floor area and the lower-floor area in a cell.
In the process of implementing the present invention, the inventor finds at least the following two problems in solution 1 in the conventional art.
Problem 1: The system capacity is decreased. The repeater raises the noise floor of the Base Station. The rise of the noise floor interferes with all users in the same cell, and increases interference to neighboring cells. Moreover, in the uplink direction, the RF module in the Base Station receives signals of User Equipment (UE) in multiple coverage areas simultaneously, and the uplink signals lead to interference between different areas; in the downlink direction, the UE in a coverage area receives the downlink signals sent to the UE in other coverage areas while receiving the downlink signals sent to this UE, and the downlink signals lead to interference between different areas. Such factors affect the system capacity.
Problem 2: If multiple areas in a cell need to be split into cells, additional RF modules need to be set in the Base Station, and re-cabling is required for the RF modules and the local end in the Base Station. Therefore, the cell splitting is costly and difficult.
In the process of implementing the present invention, the inventor finds at least the following two problems in solution 2 in the conventional art.
Problem 1: Interference exists between users in a cell. For example, in the uplink direction, the signals of UE 1 in the higher-floor area are gathered by the digital combiner to the BBU, and lead to interference to UE 2 in the lower-floor area.
Problem 2: The downlink capacity is decreased. For example, in the downlink direction, if only UE 2 in the lower-floor area is in a conversation, the transmitting power of RRU 2 is 1 w. However, due to principles of the digital combiner and divider unit, the transmitting power of RRU 1 is 1 w too. For RRU 1 , such power is wasted, and is equivalent to decrease of the downlink capacity. Besides, if UE 1 and UE 2 in different areas talk with each other, according to the digital combiner and divider unit, RRU 1 sends downlink signals to both UE 1 and UE 2 simultaneously. UE 1 receives not only the required signals, but also the downlink signals sent by RRU 1 to UE 2 , which are interference to UE 1 and further decrease the downlink capacity.
SUMMARY
The embodiments of the present invention provide a system and a method for one cell to cover multiple areas, and a network device to increase the uplink capacity and the downlink capacity, reduce the networking cost, and facilitate the implementation of cell splitting.
The system for one cell to cover multiple areas includes: (1) a Base Station which comprises a Baseband Unit (BBU), wherein the BBU of the Base Station is connected with multiple Radio Frequency (RF) groups through multiple data channels, and each RF group corresponds to an area in a cell and corresponds to a data channel; and (2) the multiple RF groups, configured to: receive uplink signals sending from a UE in the corresponding area, send the uplink signals to the BBU through the data channel corresponding to the RF group, receive downlink signals through the corresponding data channel, and send the downlink signals to the UE in the corresponding area.
In the method for one cell to cover multiple areas in an embodiment of the present invention, each RF group corresponds to an area in a cell, and each data channel corresponds to an RF group. The method includes: (1) receiving, by an RF group, uplink signals in the corresponding area, and sending the uplink signals to a BBU through the data channel corresponding to the RF group; (2) receiving, by the BBU, the uplink signals through the data channel, and sending downlink signals to the corresponding RF group through the data channel corresponding to the downlink signals; and (3) receiving, by the RF group, the downlink signals through the data channel corresponding to the downlink signals, and sending the downlink signals to the area corresponding to the RF group.
A base Station provided in an embodiment of the present invention includes: a Baseband Unit (BBU), configured to receive uplink signals of a User Equipment (UE) sending from at least one Radio Frequency (RF) group of multiple RF groups through at least one data channel of multiple data channel, and send downlink signals to at least one RF group of the multiple RF groups through the data channel corresponding to the downlink signals; wherein, the BBU is connected with the multiple RF groups through the multiple data channels and each data channel corresponds to an RF group.
An RNC provided in an embodiment of the present invention includes: (1) a storing module, configured to record identifier information of a data channel that bears uplink signals according to the uplink signals found by a BBU in a Base Station; and (2) a downlink control module, configured to determine the data channel corresponding to downlink signals according to information in the downlink signals to be sent and according to the recorded identifier information of the data channel that bears the uplink signals, and output control information on the data channel corresponding to the downlink signals to the BBU of the Base Station.
The foregoing technical solution reveals that: In the embodiments of the present invention, multiple data channels of the BBU are applied; each data channel is connected with an RF group so that the RF group can exchange signals with the BBU through the corresponding data channel Therefore, in the uplink direction, the BBU can receive the uplink signals in the areas corresponding to different RF groups through multiple data channels; when the uplink signals in different areas are sent to the BBU through different data channels, the interference caused by the uplink signals between different areas is avoided, and the uplink capacity is improved; in the downlink direction, the BBU sends downlink signals to the UEs in different areas through different data channels; when the downlink signals in different areas are sent through different data channels, the interference caused by the downlink signals between different areas is avoided, and the downlink capacity is improved. Moreover, in the case that downlink signals do not need to be sent in the area corresponding to one RF group but need to be sent in the areas corresponding to other RF groups, power transmitting is not required in all RF groups, and the downlink capacity is further improved. When multiple areas in a cell are split into multiple cells, no re-cabling is required, thus reducing the cost of cell splitting and facilitating the implementation of cell splitting.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is the first schematic diagram of one cell covering multiple areas through “Base Station+repeater” in the conventional art;
FIG. 2 is the second schematic diagram of one cell covering multiple areas through “Base Station+repeater” in the conventional art;
FIG. 3 is a schematic diagram of one cell covering multiple areas through “BBU+RRU” in the conventional art;
FIG. 4 shows a system for one cell to cover multiple areas in an embodiment of the present invention;
FIG. 5 is the first schematic diagram of an application scenario of a system for one cell to cover multiple areas in an embodiment of the present invention;
FIG. 6 is the second schematic diagram of an application scenario of a system for one cell to cover multiple areas in an embodiment of the present invention; and
FIG. 7 is a schematic flow chart describing an embodiment of a method for one cell to cover multiple areas.
DETAILED DESCRIPTION
A system for one cell to cover multiple areas in an embodiment of the present invention includes multiple RF groups and at least one BBU. The BBU is connected with multiple RF groups through multiple data channels That is, one BBU corresponds to multiple data channels, and is connected with an RF group through a data channel The data channel is configured to exchange information between the RF group and the BBU. The data channel may include an antenna interface of the BBU, or include a digital-analog conversion module between the RF group and the BBU. This embodiment of the present invention does not restrict the style of the data channel
In the embodiments of the present invention, one RF group corresponds to an area in a cell. That is, one RF group covers an area in a cell. The area in the embodiments of the present invention is specific to an RF group, namely, the scope covered by an RF group is regarded as an area. For example, area C in FIG. 1 serves as an area, and corresponds to an RF group, and building A and building B serve as another area and correspond to an RF group. That is, one RF group covers area C, and the other RF group covers building A and building B.
In the embodiments of the present invention, the quantity of the RF groups depends on the quantity of data channels That is, the quantity of the RF groups may keep consistent with the quantity of the data channels For example, if a BBU corresponds to n data channels, the quantity of the RF groups may be n. In this case, an RF group may correspond to a data channel In the embodiments of the present invention, the quantity of the RF groups may also be less than the quantity of data channels For example, if a BBU corresponds to 5 data channels, the quantity of the RF groups may be an integer between 1 and 5. In this case, some data channels may correspond to no RF group.
The RF group is configured to send uplink signals to the BBU through a data channel, and send downlink signals from the data channel The uplink signals received by the RF group are sent by the UE in coverage area of the RF group. After receiving the uplink signals from the UE, the RF group sends the uplink signals to the BBU through the corresponding data channel After receiving the downlink signals on the data channel, the RF group sends the downlink signals to the UE in coverage area of the RF group.
The BBU is configured to receive uplink signals and send downlink signals through multiple data channels The BBU may receive uplink signals of the UEs in different areas in a cell from multiple data channels. The BBU may send downlink signals through the corresponding data channel For example, when the downlink signal is sent to a UE in an area, the BBU may send the downlink signal through a data channel corresponding to an RF group that covers the UE. In this way, other RF groups do not perform transmitting operations for this downlink signal, thus avoiding decrease of the downlink capacity mentioned in the second solution in the conventional art.
When the BBU receives the uplink signal, the BBU may search each data channel respectively. After an uplink signal is found on the data channel, the BBU performs subsequent processing for the uplink signal found on the data channel The signal processing may be finger demodulation, channel estimation, maximum ratio combination, or decoding, or any combination thereof This embodiment of the present invention does not restrict the process of processing the uplink signals. If the BBU finds no uplink signal on a data channel, the signals such as noise on the data channel are not involved in the subsequent signal processing, thus avoiding interference caused by noise to the uplink signals.
When sending the downlink signals, the BBU may send the downlink signals through the corresponding data channel according to the control of the RNC, or send the downlink signals through the corresponding data channel according to its own control. The process of control on sending the downlink signals through the corresponding data channel may be implemented by selecting the data channel corresponding to the downlink signals intelligently according to the information about the received uplink signals. For example, in the process of receiving the uplink signals through the data channel, the BBU may determine the data channel that bears the received uplink signals. The BBU may send the identifier information of the data channel that bears the uplink signals to the RNC, and the RNC may determine the data channel corresponding to downlink signals according to the identifier information of the data channel that bears the received uplink signals and according to the information in the downlink signals. Therefore, the BBU may send the downlink signals according to the data channel determined by the RNC. The BBU may record the identifier information of the data channel that bears the uplink signals. In this way, the BBU may determine the data channel corresponding to the downlink signals according to the recorded identifier information of the data channel that bears the uplink signals and according to the information in the downlink signals, and send the downlink signals through the determined data channel The identifier information of the data channel that bears the uplink signals may include the identifier information of the uplink signals and the identifier information of the data channel
In this embodiment, the BBU includes: multiple Searchers, a signal processing unit, and a downlink sending module.
Each Searcher corresponds to a data channel, namely, a Searcher corresponds to an RF group. The Searcher searches the corresponding data channel to check whether any uplink signals exist on the data channel When finding any uplink signal on the data channel, the Searcher sends the uplink signal to the signal processing unit. If the Searcher finds no uplink signal on the corresponding data channel, the signals such as noise on the data channel are not sent to the signal processing unit, thus avoiding interference caused by noise to the uplink signals. After searching out any uplink signal on the data channel, the Searcher may output the identifier information of the data channel that bears the uplink signals.
The signal processing unit is configured to process the uplink signals transmitted by the Searcher. The processing may be finger demodulation, signal estimation, maximum ratio combination, or decoding, or any combination thereof. Accordingly, the signal processing unit includes but is not limited to: a finger demodulator, a channel estimating module, a Maximum Ratio Combination (MRC) module, or a decoder, or any combination thereof. The processing performed by the signal processing unit for the uplink signals may be set according to the requirements in the actual network. The process of the Base Station processing uplink signals in the conventional art is applicable. This embodiment of the present invention does not restrict how the signal processing unit processes the uplink signals.
The downlink sending module is configured to send the downlink signals through the corresponding data channel according to the received control information. The control information received by the downlink sending module may be transmitted from other modules in the BBU, or from the RNC.
If the control information received by the downlink sending module is transmitted from other modules in the BBU, the BBU further includes a storing module and a downlink control module.
The storing module is configured to record identifier information of the data channel that bears the uplink signals according to the uplink signals found by the Searcher. For example, the storing module receives and stores the identifier information of the data channel that bears the uplink signals output by the Searcher. The identifier information of the data channel that bears the uplink signals may include the mapping relation between the uplink signal and the data channel.
The downlink control module is configured to determine the data channel corresponding to downlink signals to be sent according to the information in the downlink signals and identifier information of the data channel that bears the uplink signals stored in the storing module, and output control information to the downlink sending module.
The storing module and the downlink control module may also be set in the RNC.
The RF group in this embodiment is appropriate only if it can receive downlink signals and send the downlink signals to the UE, and can receive uplink signals of the UE and send the uplink signals to the BBU. The RF group may be any type of receiving and sending apparatuses in the conventional art. For example, the RF group may be a combination of a remote RF module, an RF module, and a combiner, or a combination of multiple remote RF modules and a remote RF module hub (RHUB), or a combination of a repeater, a coupler and an RF module, or a combination of a trunk amplifier, a coupler, and an RF module. This embodiment of the present invention does not restrict the style of the RF group.
A system for one cell to cover multiple areas in an embodiment of the present invention is described below with reference to the accompanying drawings.
FIG. 4 shows a system for one cell to cover multiple areas in an embodiment of the present invention. In FIG. 4 , the system for one cell to cover multiple areas includes n (n 1) RF groups and a BBU.
FIG. 4 illustrates only three types of RF groups. In RF group 1 (RGroup- 1 ), an RRU and an RF module are connected with the combiner. The uplink signals are sent to the BBU over the corresponding data channel through an RRU/RF and a combiner; and the downlink signals are sent to the UE in the area covered by RGroup- 1 over the corresponding data channel through a combiner, an RRU, and an RF module. Two RRUs in RF group 2 (RGroup- 2 ) are connected with one RHUB. Nevertheless, RGroup- 2 may include more RRUs. The uplink signals are sent to the BBU over the corresponding data channel through an RRU and an RHUB, and the downlink signals are sent to the UE in the area covered by RGroup- 2 over the corresponding data channel through an RHUB and an RRU. A repeater in RF group n (RGroup-n) is connected with the RF module through a coupler. The repeater in RGroup-n may also be a trunk amplifier, the uplink signals are sent to the BBU over the corresponding data channel through a repeater, a coupler, and an RF, or sent to the BBU over the corresponding data channel through an RF directly, and the downlink signals are sent to the UE in the area covered by RGroup-n over the corresponding data channel through an RF, or sent to the UE in the area covered by RGroup-n over the corresponding data channel through an RF, a coupler, and a repeater. Other implementation modes of the RF group are not enumerated here any further.
The BBU in FIG. 4 includes n 1) Searchers, a Finger Demodulator, a Channel Estimator module, an MRC module, and a Decoder. The Finger Demodulator, the Channel Estimator module, the MRC module, and Decoder make up a signal processing unit. The signal processing unit may also be set according to the network conditions. Other modes of the signal processing unit are not elaborated here any further. FIG. 4 does not show the Downlink Sending module in the BBU, the Storing module or the Downlink Control module in the system.
Each Searcher searches for the corresponding RF group (RGroup) as an antenna of Cell 1 (BBU 1 ).
In the uplink direction, each Searcher searches for the finger of the corresponding RGroup. Searching for a finger is equivalent to searching for an uplink signal. If no finger of the RGroup is found, the data such as noise in the corresponding data channel is not involved in the finger demodulation and the subsequent signal processing. That is, such data (noise) does not cause any interference to the uplink signals of the current UE, starting from the Searcher. That improves the uplink capacity of the cell. According to the search result of the Searcher, the Searcher may output the information about the RGroup that send the uplink signals of the UE. That is, the Searcher may output the identifier information of the data channel that bears the uplink signals.
In the downlink direction, the BBU or RNC may determine the data channel corresponding to the downlink signals according to the search results of the uplink signals. For example, the BBU or RNC may determine the data channel corresponding to the downlink signals according to the Searcher output which reveals the RGroup that sends the uplink signals. Therefore, the BBU may transmit the downlink signals to the RGroup in the area that covers the UE through the corresponding data channel, without the need of transmitting downlink signals to all RGroups in the cell.
In the conventional art, any UE in the same cell may receive the downlink signals of all UEs in the cell. In this embodiment, although multiple RGroups belong to the same cell, the BBU may make downlink signals be transmitted in only the area that covers the UE according to the RF group selected intelligently. In this way, the UE receives only the downlink signals of all UEs in the area covered by the RGroup of this UE rather than receives the downlink signals of all UEs in the area covered by other RGroup in this cell, thus reducing interference between downlink signals, saving the downlink transmitting power, increasing the downlink capacity, and decreasing the operation cost.
The system in this embodiment can select an area intelligently for transmitting downlink signals. Therefore, the system in this embodiment is known as a Smart Multi-RRU/RF One Cell (SMROC) system.
As shown in FIG. 5 and FIG. 6 , the system provided in an embodiment of the present invention is elaborated below with reference to specific application scenarios. The application scenario of FIG. 5 and FIG. 6 is the same as the application scenario of FIG. 1 and FIG. 2 .
In FIG. 5 , three areas, namely, area C, building A, and building B belong to the same cell. RGroup- 1 covers the area of building A, RGroup- 2 covers the area of building B, and the RF module in the Base Station covers area C. The RF module in the Base Station, RGroup- 1 , and RGroup- 2 are connected with the BBU in the Base Station. At the beginning of network construction, area A, area B, and area C may be one cell, and the three areas in the cell may share the baseband resources in the Base Station. Three areas A, B, and C may exchange signals with the BBU through three data channels In this way, the UE in any of areas A, B, and C never receives the downlink signals of the UE in other areas, thus avoiding the downlink signal interference between area A, area B and area C, and increasing the downlink capacity. In the uplink direction, area A, area B, and area C send uplink signals to the BBU through different data channels, thus avoiding the uplink signal interference between area A, area B, and area C, and increasing the uplink capacity. Moreover, in the subsequent network evolution, upgrade, and expansion, if three areas in a cell need to be split into three cells, that purpose may be accomplished without cable adjustment, thus avoiding high costs and difficulty of cell splitting caused by re-cabling. If three areas in a cell need to be split into three cells, and the RGroup- 1 and RGroup- 2 include an RRU, no RF module needs to be added for RGroup- 1 and RGroup- 2 in the Base Station.
In FIG. 6 , floors 1 - 10 and floors 11 - 20 belong to the same cell. RGroup- 1 covers the higher-floor area, and RGroup- 2 covers the lower-floor area. Therefore, two areas (higher-floor area and lower-floor area) in a cell are covered through two RF groups. At the beginning of network construction, the higher-floor area and the lower-floor area may be one cell, and two areas in the cell may share the baseband resources in the Base Station. The higher-floor area and the lower-floor area may exchange signals with the BBU through two data channels In this way, the UE in neither the higher-floor area nor the lower-floor area receives the downlink signals of the UE in other areas, thus avoiding the downlink signal interference between the higher-floor area and the lower-floor area and increasing the downlink capacity. In the uplink direction, the higher-floor area and the lower-floor area send uplink signals to the BBU through different data channels, thus avoiding the uplink signal interference between the higher-floor area and the lower-floor area, and increasing the uplink capacity. Moreover, in the application scenario in FIG. 6 , only two RF modules need to be set for the RF group in this embodiment. As shown in FIG. 6 in comparison with FIG. 2 , an RF module is saved in the system in this embodiment, and the networking cost is reduced. Moreover, in the subsequent network evolution, upgrade, and expansion, if two areas in a cell need to be split into two cells, that purpose may be accomplished without cable adjustment, thus avoiding high costs and difficulty of cell splitting caused by re-cabling. If two areas in a cell need to be split into two cells, and the RGroup- 1 and RGroup- 2 include an RRU, no RF module needs to be added for RGroup- 1 and RGroup- 2 in the Base Station.
The Base Station and the RNC in this embodiment are the same as those described in the foregoing system embodiment, and are not repeated here any further.
A method for one cell to cover multiple areas in an embodiment of the present invention is described below.
The method involves multiple RF groups and at least one BBU. One BBU corresponds to multiple data channels, a BBU is connected with an RF group through a data channel, and an RF group covers an area in a cell. The area, the quantity of RF groups, and the RF group implementation mode are the same as those described in the foregoing system embodiment.
The method in this embodiment involves a process of transmitting uplink signals and downlink signals.
In the uplink direction, the RF group receives the uplink signals from the UE, and sends the uplink signals to the BBU through the corresponding data channel When the BBU searches multiple data channels for uplink signals, the BBU processes the found uplink signals. If the BBU finds no uplink signal on a data channel, the BBU does not need to process the signals such as noise on the data channel, thus avoiding interference caused by noise to the uplink signals. After finding an uplink signal, the BBU may record the identifier information of the data channel that bears the uplink signal, and may send the identifier information of the data channel to the RNC. The signal processing and the recording of the identifier information of the data channel that bears the uplink signal are the same as the counterpart processing in the system embodiment described above.
In the downlink direction, the BBU uses the data channel corresponding to the downlink signals to send downlink signals to the corresponding RF group, and the RF group sends the downlink signals to the UE in its coverage area after receiving the downlink signals on the data channel The BBU may send downlink signals of a UE through a data channel In some application scenarios, however, the BBU may send the downlink signals of a UE through multiple data channels When sending the downlink signals, the BBU may send the downlink signals through the corresponding data channel according to the control of the RNC, or send the downlink signals through the corresponding data channel according to its own control. The process of control on sending the downlink signals through the corresponding data channel may be implemented by selecting the data channel corresponding to the downlink signals intelligently according to the information about the received uplink signals. The process of determining the data channel corresponding to the downlink signals according to the uplink signals is the same as the counterpart process in the system embodiment described above.
In the embodiments of the present invention, in the uplink direction, the BBU may receive uplink signals in the areas corresponding to different RF groups through multiple data channels Therefore, when the uplink signals in different areas are sent to the BBU through different data channels, the uplink signal interference between different areas is avoided, and the uplink capacity is increased. Moreover, if the BBU finds no uplink signal from a data channel, the BBU does not perform subsequent processing for the signals such as noise on the data channel, and the interference caused by the signals such as noise to the uplink signals is avoided. In the downlink direction, the BBU or RNC may select the data channel corresponding to the downlink signals intelligently according to the uplink signals. In this way, the BBU may send the downlink signals to the UEs in different areas through different data channels When the downlink signals in different areas are sent through different data channels, the downlink signal interference between different areas is avoided, and the downlink capacity is increased. Moreover, in the case that the area corresponding to an RF group has no downlink signal ready for sending but the area corresponding to other RF groups has downlink signals ready for sending, the situation that all RF groups need power transmitting is avoided, and the downlink capacity is further increased. When multiple areas in the cell are split into multiple cells, no re-cabling is required, thus reducing the cost of cell splitting and facilitating the implementation of cell splitting. Moreover, when multiple areas in a cell are split into multiple cells, if the RF group includes an RRU, the system in this embodiment does need to add an RF module at the Base Station, thus reducing the networking cost and facilitating the cell splitting, namely, facilitating the upgrade and expansion in network evolution.
Although the invention has been described through several preferred embodiments, the invention is not limited to such embodiments. It is apparent that those skilled in the art can make modifications and variations to the invention without departing from the spirit and scope of the invention. The invention is intended to cover the modifications and variations provided that they fall in the scope of protection defined by the following claims or their equivalents.
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A system, method and network device for covering a plurality of areas by one cell are disclosed. The system includes: a plurality of radio frequency groups and at least one base band unit. One radio frequency group corresponds to one area of the cell, one radio frequency group corresponds to one date channel, and one base band unit is connected to a plurality of radio frequency groups through a plurality of date channels. The embodiment of the invention reduces the signal interference among each area of the same cell, increases the system capacity, and benefits cell splitting, i.e., benefits increasing the capacity and upgrading during network enhancement.
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority to U.S. patent application Ser. No. 61/569,636, which was filed Dec. 12, 2011. This priority application is hereby incorporated by reference in its entirety into the present application, to the extent that it is not inconsistent with the present application.
BACKGROUND
The invention relates generally to drilling of wells in subsurface formations. More specifically, the invention relates to monitoring and detecting kicks in a well.
During drilling of a well, drilling fluid (or “drilling mud”) is pumped from a mud pit into a drill string that is suspended in the well. The drilling mud flows down the drill string, exiting through a bit at the end of the drill string into the bottom of the well. The drilling mud then returns to the surface, carrying with it formation cuttings made by the bit. At the surface, the drilling mud flows through a mud return line into a mud treatment system, which cleans the drilling mud. The clean drilling mud is returned to the mud pit, from where the drilling mud is again pumped into the drill string. This circulation of the drilling mud continues while the bit is cutting the formation. The drilling mud performs a variety of functions, including carrying formation cuttings to the surface, cooling the bit, and controlling the hydrostatic pressure in the well such that the well does not take a kick. A well is said to take a kick whenever there is unwanted influx of formation fluids into the well.
The hydrostatic pressure in the well is controlled through the weight of the drilling mud. In spite of careful control of drilling mud weight, a well may take a kick unexpectedly. Thus the normal practice is to monitor the well for kicks so that as soon as a kick is detected measures can be put into place to circulate the kick out of the well and stabilize the well. If a kick is not detected early enough and controlled, it may result in blowout of the well. Strategies for detecting kicks generally include (i) monitoring increases in the difference between the volume of fluid pumped into the well and the volume of fluid returning from the well, (ii) monitoring increases in the difference between the rate at which fluid is pumped out of the well and the rate at which fluid is pumped into the well, (iii) monitoring fluctuations in drill pipe pressure, and (iv) monitoring increases in gas content of fluid returns from the well. It is common to use a combination of these strategies to effectively detect kicks during drilling operations.
The flow rate monitoring strategy is often used when drilling mud is not being pumped into the drill string, such as when making connections between drill pipes. The principle here is that if the well inflow is zero and the well is stable, the well outflow should also be zero. The current practice when using this strategy is to physically inspect the mud return line to confirm that flow stopped when the mud pump(s) stopped pumping drilling mud into the drill string. Rig personnel can look inside the bell nipple, which is a large diameter pipe at the top of the well to which the mud return line is attached, or further down the mud return line, such as at the shale shakers, to visually observe any signs of flow. However, when the rig crew first shuts the mud pump down, it generally takes some period of time for well outflow to drop to zero. To detect a kick early, the rig personnel inspecting the mud return line with the naked eye would need to be able to quickly distinguish between residual flow and anomalous flow that may be indicative of a kick.
SUMMARY
In one aspect, a method of monitoring a well for unwanted formation fluid influx includes acquiring measurements of well outflow during a period in which drilling operations are performed for the well. The method includes determining occurrences of stagnant flow events during the period and generating an outflow signature from the well outflow measurements for each stagnant flow event. The method includes displaying at least a portion of the outflow signatures sequentially in time of occurrence. The method includes analyzing each outflow signature for an anomaly.
It is to be understood that both the foregoing general description and the following detailed description are exemplary of the invention and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification. The drawings illustrate various embodiments of the invention and together with the description serve to explain the principles and operation of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The following is a description of the figures in the accompanying drawings. The figures are not necessarily to scale, and certain features and certain views of the figures may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness.
FIG. 1 shows a system for drilling a well.
FIG. 2 shows a block diagram of a system for monitoring a well.
FIG. 3A shows a partial outflow signature on a display device.
FIG. 3B shows a complete outflow signature on a display device.
FIG. 4 shows a sequence of outflow signatures on a display device.
DETAILED DESCRIPTION
It is to be understood that the following disclosure describes several exemplary embodiments for implementing different features, structures, or functions of the invention. Exemplary embodiments of components, arrangements, and configurations are described below to simplify the present disclosure; however, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the invention. Additionally, the present disclosure may repeat reference numerals and/or letters in the various exemplary embodiments and across the Figures provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various exemplary embodiments and/or configurations discussed in the various Figures. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact. Finally, the exemplary embodiments presented below may be combined in any combination of ways, i.e., any element from one exemplary embodiment may be used in any other exemplary embodiment, without departing from the scope of the disclosure.
Additionally, certain terms are used throughout the following description and claims to refer to particular components. As one skilled in the art will appreciate, various entities may refer to the same component by different names, and as such, the naming convention for the elements described herein is not intended to limit the scope of the invention, unless otherwise specifically defined herein. Further, the naming convention used herein is not intended to distinguish between components that differ in name but not function. Additionally, in the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to.” All numerical values in this disclosure may be exact or approximate values unless otherwise specifically stated. Accordingly, various embodiments of the disclosure may deviate from the numbers, values, and ranges disclosed herein without departing from the intended scope. Furthermore, as it is used in the claims or specification, the term “or” is intended to encompass both exclusive and inclusive cases, i.e., “A or B” is intended to be synonymous with “at least one of A and B,” unless otherwise expressly specified herein. For the purposes of this application, the term “real-time” means without significant delay.
FIG. 1 shows an example of a system 100 for drilling a well 102 in subsurface formation 103 . A drill string 104 extends through a rotary table 106 , a bell nipple 108 , blowout preventers 110 , 112 , and a wellhead 114 into the well 102 . The rotary table 106 is mounted in a drill floor 116 , and the bell nipple 108 , blowout preventers 110 , 112 , and wellhead 114 are below the rotary table 106 . (In marine drilling, the blowout preventers and wellhead would be located at or near the seafloor and a marine riser may extend between the seafloor and the drill floor.) The drill string 104 is coupled at the top to a top drive 118 , which is coupled to a swivel 120 . A traveling block 122 coupled to the swivel 120 hangs down from a crown block 124 at the top of a derrick 126 . The traveling block 122 travels up and down the derrick 126 via a pulley system. The bell nipple 108 is in hydraulic communication with a mud pit 128 via a return flow line 130 . A shale shaker 132 filters debris out of the drilling mud flowing into the mud pit 128 . A mud pump 134 is in hydraulic communication with the mud pit 128 via a suction flow line 136 . The mud pump 134 is also in hydraulic communication with the swivel 120 via a discharge flow line 138 . The swivel 120 is in hydraulic communication with the top drive 118 , which is in hydraulic communication with the drill string 104 .
The mud circulation system starts at the mud pit 128 containing the drilling mud. The mud pump 134 pumps drilling mud from the mud pit 128 into the swivel 120 . From the swivel 120 , the drilling mud flows into the top drive 118 and then into the drill string 104 . The drilling mud flows down the drill string 104 and exits into the bottom of the well 102 through a bit 140 . At the bottom of the well 102 , the drilling mud commingles with formation cuttings made by the bit 140 . The drilling mud with the formation cuttings is then forced up a return annulus 142 defined between the well 102 and the drill string 104 into the bell nipple 108 . From the bell nipple 108 , the drilling mud flows through the shale shaker 132 into the mud pit 128 . The shale shaker 132 removes debris from the drilling mud. Additional conditioning of the drilling mud may occur inside the mud pit 128 before the drilling mud is again circulated through the system. (For a dual-bore drill string, the return annulus would be defined inside the drill string. Also, a device other than a bell nipple may be used to divert the drilling mud from the return annulus to the mud pit.)
FIG. 2 shows a system 200 for monitoring the well 102 (in FIG. 1 ). The system 200 has a measurement module 202 , a processing module 204 , and a display device 206 . The measurement module 202 includes one or more sensors, such as sensors 208 , 210 , and 212 , for measuring one or more parameters related to well monitoring. In one embodiment, the sensor 208 measures well outflow, which is the rate at which drilling mud flows out of a well. In one embodiment, the sensor 210 measures well inflow, which is the rate at which drilling mud is pumped into a drill string in a well. In one embodiment, the sensor 212 measures movement, such as axial movement or rotation, of a drill string performing operations in a well. In FIG. 1 , the sensor 208 is arranged in the return flow line 130 to measure well outflow. The sensor 208 may be any flowmeter that can work with particulate fluid. The flowmeter may make relative or absolute measurements. In one embodiment, the sensor 208 is a paddle-type flowmeter. The sensor 210 is arranged in the discharge flow line 138 to measure well inflow. The sensor 212 is arranged on the top drive 118 to measure movement of the drill string 104 . It is possible to arrange the sensors 208 , 210 , 212 at locations other than indicated in FIG. 1 as long as the desired parameters can be measured at the other locations.
In FIG. 2 , the processing module 204 receives the measurements made by the sensors 208 , 210 , 212 via an input interface 214 . Transmission of measurements from the sensors 208 , 210 , 212 to the processing module 204 may be direct or indirect. In the latter case, for example, measurement signals from the sensors 208 , 210 , 212 may be preprocessed or stored elsewhere before being transmitted to the processing module 204 . The processing module 204 includes a memory or storage device 216 for holding the measurements as well as other data and programs, such as a well monitoring program. The memory or storage device 216 may take the form of one or more floppy disks, a CD-ROM or other optical disk, a magnetic tape, a read-only memory chip (ROM), and other forms of memory or storage device well known in the art or subsequently developed. The processing module 204 has a processor device 218 , which can read programs and data on the memory or storage device 216 . The processing module 208 executes programs and controls operations of the processing module 204 . The programs executed by the processor device 218 may be in binary form or object code, in source code, or in some intermediate form such as partially complied code. The processing module 204 communicates with the display device 206 via an output interface 220 . The communication interfaces 214 , 216 of the processing module 204 may include wired or wireless links that allow the system to operate in a substantially real-time manner.
The processing module 204 generates outflow signatures for stagnant flow events. A stagnant flow event occurs when drilling mud is not being pumped into the drill string 104 (in FIG. 1 ) and when the drill string 104 is not moving. Typically, stagnant flow events occur when making up or breaking out pipe connections. The outflow signatures are generated from the well outflow measurements. However, to generate the outflow signatures for the stagnant flow events, knowledge of the starting time and ending time of each stagnant flow event is needed. In one embodiment, this knowledge may be gleaned from the well inflow measurements made by the sensor 210 and from the drill string movement measurements made by the sensor 212 . It should be noted that other records besides well inflow measurements and drill string movement measurements may be used to determine the starting times and ending times of stagnant flow events. For example, the controller of the mud pump 134 (in FIG. 1 ) may send messages to the processing module 204 whenever there is a switch in the state of the mud pump 134 , and the controller of the top drive 118 (in FIG. 1 ) may send messages to the processing module 204 whenever there is a switch in the state of the top drive 118 . The processing module 204 can make note of the time of the messages and use it to determine the starting and ending times of stagnant flow events.
The processing device 214 executes the well monitoring program while drilling operations are being carried out on the well 102 (in FIG. 1 ). Drilling operations encompass all operations related to drilling of the well 102 . The well monitoring program, when executed, causes the processing module 204 to listen for stagnant flow events. Listening may involve requesting for and receiving data that would indicate whether drilling fluid is being pumped into the drill string 104 or not and whether the drill string 104 is moving or not. When the well monitoring program detects a stagnant flow event, the well monitoring program causes the processing device 218 to generate an outflow signature for the stagnant flow event and causes the display device 206 to render the outflow signature as the stagnant flow event is unfolding. The well monitoring program causes the processing device 218 to analyze the outflow signature to determine whether the outflow signature includes an anomaly that may indicate a kick or other well control event. The well monitoring program may cause the processing device 218 to generate an alarm if it is determined that the outflow signature includes an anomaly or otherwise indicates a potential kick or well control event. How the well monitoring program works will be further explained by way of an example.
For illustration purposes, at some t 1 — start , a stagnant flow event S 1 starts. The processing module 204 detects that the stagnant flow event S 1 has started and sends a signal to the display device 206 to display a start marker corresponding to t 1 — start . Then, the processing module 204 starts processing the well outflow measurements made from time t 1 — start to generate an outflow signature that is representative of the well outflow from time t 1 — start . The processing module 204 sends signals to the display device 206 as the outflow signature is generated, and the display device 206 renders the outflow signature relative to the start marker. FIG. 3A shows outflow signature s 1 on display device 206 as the outflow signature is being generated. An outflow signature is an impression of a well outflow and shows simply how the well outflow is trending with time, i.e., whether the well outflow is increasing or decreasing or not changing and whether any increase or decrease in well outflow is fast or slow or small or large. The processing module 204 continues processing the well outflow measurements and updating the outflow signature until the time t 1 — end when the stagnant flow event S 1 ends. The processing module 204 sends a signal to the display device 206 to display an end marker corresponding to time t 1 — end . FIG. 3B shows the complete outflow signature s 1 on the display device 206 .
After the stagnant flow event S 1 has ended, the processing module 204 goes back to listening for the next stagnant flow event. For each new stagnant flow event detected, the processing module 204 will generate a new outflow signature and send signals to the display device 206 to render the new outflow signature along with a few or all of the previous outflow signatures. On the display device 206 , the outflow signatures are displayed sequentially in time of occurrence. Also, the outflow signatures are separated spatially so that one outflow signature can be told apart from another outflow signature visually. FIG. 4 shows an example of a sequence of outflow signatures on the display device 206 . The sequence includes completed outflow signatures s 1 , s 2 and outflow signature s 3 that is being generated. Drilling personnel can visually observe the outflow signatures on the display device 206 as they are being generated by the processing device 218 (in FIG. 2 ). If rig personnel see an outflow signature that is anomalous, the rig personnel may assume that the well has taken a kick and raise an alarm. Alternatively, the processing module 204 can analyze the outflow signatures and trigger an alarm if an anomalous outflow signature is detected. The alarm may be acoustic or visual. In the latter case, the alarm may graphical or textual. The alarm could be sent to a control room to enable the rig crew to take appropriate actions.
During a stagnant flow event, the well inflow will be zero. If the well has not taken a kick, the well outflow should also be zero during a stagnant flow event. Initially, the well outflow will not be zero due to residual flow. However, the well outflow should drop to zero and stay at zero if the well is stable. Therefore, an outflow signature may be considered anomalous if the outflow signature does not show a generally decreasing flow. In other words, an outflow signature is anomalous if it indicates non-residual well outflow. In such a case, the processing module 204 of FIG. 2 may trigger an alarm. Another way that the processing module 204 may determine when an outflow signature is anomalous is by pattern recognition. For example, the processing module 204 may compare each outflow signature to a set of test outflow patterns known to be indicative of a kick in a well, i.e., a set of anomalous flow patterns. If the pattern of the outflow signature matches any of the test outflow patterns, the processing module 204 may raise an alarm. In certain embodiments, the processing module 204 may compare an outflow signature to a previously generated outflow signature to determine whether the outflow signature includes an anomaly that may indicate a kick or other well control event.
In addition to monitoring well outflow during stagnant flow events, other kick indicators may be monitored. For example, the volume of the mud pit 128 (in FIG. 1 ) may be monitored during tripping events. Abnormal gains in the volume of the mud pit 128 may indicate that a kick is underway in the well 102 (in FIG. 1 ). A suitable sensor, such as an infrared camera, may be used to monitor the fluid level in the mud pit 128 , which can be translated to the volume of fluid in the mud pit 128 . The measurements may be transmitted to the processing module 204 , which can process the measurements and cause the display 206 to render a volume history of the mud pit. The volume history can be in the form of volume signatures, where each volume signature would correspond to a tripping event. The volume signature would simply show how the volume of the mud pit is trending. The volume history will typically be shown separately from the outflow signatures. However, the time frame of the volume history displayed may correspond to that of the outflow signatures displayed. This would allow both the volume history and outflow signature to be used to detect a kick in the well. If the processing module 204 finds an anomalous outflow signature during analysis of outflow signatures, as described above, the processing module 204 can check the volume history to see if there has been an abnormal gain in the volume of the mud pit 128 before triggering an alarm that the well may have taken a kick.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.
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A method of monitoring a well for unwanted formation fluid influx is disclosed. Measurements of well outflow are acquired during a period in which drilling operations are performed for the well. Occurrences of stagnant flow events during the period are determined. An outflow signature is generated from the well outflow measurements for each stagnant flow event. The outflow signatures are displayed sequentially in time of occurrence. Each outflow signature is analyzed for an anomaly.
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RELATED APPLICATIONS
[0001] The present invention is a continuation-in-part of and claims priority to U.S. patent application Ser. No. 12/547,708 entitled “INSTRUMENT FOR CONTINUOUS DISCHARGE OF ANESTHETIC DRUG” filed Aug. 29, 2009.
COPYRIGHT NOTICE
[0002] A portion of the disclosure of this patent document contains material, which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever.
FIELD OF THE INVENTION
[0003] Embodiments of the invention described herein generally relate to the discharge of anesthetic drug. More specifically, embodiments of the present invention are directed towards instruments and methods for discharging an anesthetic drug on a continuous basis for use as a nerve block.
BACKGROUND OF THE INVENTION
[0004] Regional anesthesia refers to anesthetizing only a region of the body, usually in the region where surgery is performed or where acute or chronic pain from any other cause is present. A nerve block accomplishes this task, by administering a local anesthetic agent, such as novocaine, bupivacaine or lidocaine, to the plexus of a nerve. Traditionally, a nerve block was administered using a needle to locate the target nerve and to then insert the anesthetic agent through the needle in order to make contact with the nerve, commonly referred to as a single injection nerve block or single-shot nerve block. One of the major disadvantages of single injection nerve blocks was that the duration of acute pain would be longer than the duration of the single injection nerve block.
[0005] As a result, continuous nerve blocks emerged, which utilized an epidural catheter that was threaded through a needle once the needle was properly placed adjacent to the target nerve, and used to deliver variable amounts of the anesthetic agent to the target nerve. In order to properly position the needle on or near the target nerve, a nerve stimulator, such as an electrical current, would be used. Later advances utilized a nerve stimulator on the epidural catheter as well, in order to properly position the epidural catheter on or near the target nerve.
[0006] More recently, continuous nerve blocks have been utilized where a needle is properly placed adjacent to the target nerve using ultrasound technology, instead of a nerve stimulator. Subsequent to the proper placement of the needle, an epidural catheter is threaded through the needle and positioned on or near the nerve using a nerve stimulator. However, the major disadvantage to this existing technique is that the catheter is not reliably visible using ultrasound technology, which in turn prevents the epidural catheter to be optimally positioned on or near the target nerve. For example, the current technique requires that the catheter be advanced far down along the nerve to ensure that it is positioned on the nerve for the duration of the continuous block, which in turn may result in coiling of the catheter around the nerve, potentially causing damage to the nerve upon removal of the catheter. In addition, coiling of the catheter is not visible using ultrasound technology, as such technology only allows for a two dimensional view. Furthermore, the current technique requires tunneling of the catheters in order to avoid any dislodgment of the catheters, which also leads to potential damage to the nerves from broken or leaking catheters, as well as infections.
[0007] Therefore, there exists a need for a catheter instrument that is visible on an ultrasound image, which would allow for the catheter to be optimally positioned on or near a target nerve and avoid any potential damage from coiling or tunneling of the catheter.
SUMMARY OF THE INVENTION
[0008] The present invention is directed towards instruments and methods for discharging an anesthetic drug on a continuous basis for use as a nerve block. In accordance with the present invention, a catheter is provided that comprises an electrically conductive wire, a protective sheath and an inflatable balloon. The electrically conductive wire has a distal end terminating at an electrically conductive wire tip at a distal end of the catheter. A proximal end of the electrically conductive wire extends proximally beyond a proximal end of the catheter, the electrically conductive wire being capable of conveying an electrical impulse from the proximal end of the wire to the wire tip. The sheath comprises a central bore and an outer surface, the sheath covering the central portion of the catheter and a portion of the wire. The balloon is at the distal end of the catheter capable of being inflated and deflated. A balloon channel terminates within the inflatable balloon at the distal end of the catheter and extends proximally along the length of the catheter to the proximal end of the catheter. The balloon channel, within the inflatable balloon, has a balloon channel opening at a distal end of the balloon channel, capable of releasing an injected substance into the balloon. The balloon channel further includes a channel injection opening at a proximal end of the balloon channel, capable of receiving an injected substance. According to one embodiment, the catheter may be fed through a needle assembly into the body of a patient. According to another embodiment, the catheter may be placed over the length of a needle assembly into the body of a patient.
[0009] The proximal end of the electrically conductive wire allows for contact with an electrical impulse, which allows for the electrically conductive wire to be placed adjacent to the target nerve. The balloon channel injection opening can be attached to an apparatus, such as a syringe, which would allow for the injection of a liquid or gaseous substance, such as air or saline, in order to expand the inflatable balloon and properly position the catheter using ultrasound technology. Once the catheter is properly and securely positioned, an anesthetic drug can be administered to the target nerve through the central bore of the catheter, by facilitating the attachment of a device for the delivery of the anesthetic through the proximal end of the catheter.
[0010] In another embodiment, a second inflatable balloon located at the central portion of the catheter can be inflated, which would allow for the first inflatable balloon to be deflated, while keeping the catheter securely fastened. The first inflatable balloon could be re-inflated at any time in order for an ultra sound image to confirm that the catheter is securely positioned.
[0011] Using the above described apparatuses solves the disadvantage of the existing technique of placing a catheter into a body for continuous administration of an anesthetic, namely allowing for the epidural catheter to be optimally positioned on or near the target nerve through ultrasound technology. By utilizing the above-described inflatable balloon, the distal end of the catheter becomes visible on an ultrasound image, allowing for the distal end of the catheter to be properly positioned on or near the target nerve. In addition, by utilizing the inflatable balloon, the catheter can maintain its correct positioning on or near the nerve, without requiring the catheter be placed far down along the nerve, which in turn avoids any potential damage that may result in coiling of the catheter around the nerve. Furthermore, the inflatable balloon also the necessity of tunneling of the catheter, which in turns helps to prevent any potential damage to the nerve upon removal of the catheter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The invention is illustrated in the figures of the accompanying drawings which are meant to be exemplary and not limiting, in which like references are intended to refer to like or corresponding parts, and in which:
[0013] FIG. 1 presents a side elevational view of a catheter assembly;
[0014] FIG. 2 a presents a side elevational view of a portion of the catheter assembly between the distal and proximal ends;
[0015] FIG. 2 b presents a side elevational view of a portion of the catheter assembly between the distal and proximal ends in an alternative embodiment;
[0016] FIG. 3 presents a side elevational view of the catheter assembly in an expanded state;
[0017] FIG. 4 presents a side elevational view of an alternative embodiment of the catheter assembly;
[0018] FIG. 5 presents a side elevational view of an alternative embodiment of the catheter assembly in an expanded state.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0019] In the following description, reference is made to the accompanying drawings that form a part hereof, and is shown by way of illustration specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention.
[0020] FIG. 1 presents a side elevational view of a catheter assembly 100 . The catheter assembly 100 is of a diameter which allows the assembly to be inserted through a typical needle assembly and into the body of the patient. According to one embodiment, the catheter assembly has a diameter range of twelve (12) to twenty-two (22) gauge. The catheter assembly 100 includes three portions: a central portion 104 , a proximal portion 106 and a distal portion 102 . The catheter assembly 100 is placed in the body of the patient with the distal portion 102 entering the body first.
[0021] The catheter assembly 100 includes an electrically conductive wire 116 , best shown in FIG. 2 a, which spans the length of the catheter assembly 100 . At the central portion 104 of the catheter assembly 100 , a sheath 114 covers the electrically conductive wire 116 . The sheath 114 is formed from a thermoplastic or some other similar material in order to insulate an electrical charge that will be conducted through the wire 116 . The sheath 114 defines a central bore 112 through which a liquid may pass freely. At the proximal portion 106 of the catheter assembly 100 , the wire 116 is not covered by the sheath 114 and has a length that is shorter relative to central portion 104 of the catheter assembly 100 . The wire 116 is left exposed so that an electrical charge can make contact with it, in order to conduct an electrical charge down its entire length. According to one embodiment, an electric stimulator as is known in the art, can make contact with the exposed portion of the wire 116 in order to provide the electrical charge.
[0022] The distal portion 102 of the catheter assembly 100 also has a length that is shorter relative to central portion 104 of the catheter assembly 100 and is not covered by the sheath 114 . The electrically conductive wire 116 is left exposed at the distal portion 102 in order to allow the electrical charge to make contact with a target nerve (Not shown). Attached to the electrically conductive wire 116 at the distal portion 102 is an electrically conductive tip 118 , which in one embodiment, is a rounded tip made of a material capable of conducting an electrical current. According to one embodiment, the electrically conductive tip 118 is a piece of rounded metal.
[0023] In another embodiment, the electrically conductive wire of the catheter assembly 100 is a helical electrically conductive wire 130 as shown in FIG. 2 b. The wire 130 is a helical coil of wire that can also make contact with an electrical charge at the proximal portion 106 of the catheter assembly 100 , in order to conduct an electrical charge down its entire length. As shown in FIG. 2 b, the wire 130 will maintain a tightly wound nature from the central portion 104 through the proximal portion 106 of the catheter assembly 100 . In the present embodiment, the helical electrically conductive wire 130 defines the central bore 112 through which a liquid may pass freely. At the distal portion 102 of the catheter assembly 100 , the tight helix of the wire 130 will open up considerably for several revolutions of the helix, before the structure returns into a tightly wound nature at the. Attached to the wire 130 is a helical electrically conductive tip 132 , which according to one embodiment, is a rounded tip made of a material capable of conducting an electrical current. According to one embodiment, the electrically conductive tip 132 is a piece of rounded metal. In this embodiment, the wire 130 is not covered by the sheath 114 at the distal portion 102 in order to allow the electrical charge to make contact with a target nerve.
[0024] Referring back to FIG. 1 , the catheter assembly 100 further includes an inflatable balloon 126 that is located toward the distal end of the catheter assembly 100 , as shown in FIG. 1 in a deflated state. The inflatable balloon 126 can be expanded with either a gaseous substance or a liquid substance, such as saline or a local anesthetic. It is recognized that any suitable type of substance as recognized by one skilled in the art can be used to inflate the balloon, that substance being gaseous or liquid. The substance being of the base gaseous or liquid variety may include further characteristics, including for example the liquid may include micro-bubbles or similar characteristics, which enhance the visibility of the balloon as described below. A gaseous or liquid substance is delivered to the inflatable balloon 126 through a balloon channel 120 . The balloon channel 120 terminates within the inflatable balloon 126 , allowing for the gaseous or liquid substance to exit the balloon channel 120 through a balloon channel opening 124 . The balloon channel 120 extends from the opening 124 along the length of the central portion 104 and the proximal portion 106 of the catheter assembly 100 . At the proximal end of the channel 120 is a balloon channel injection opening 122 , where the gaseous or liquid substance can be injected into the channel 120 . Once the gaseous or liquid substance is injected into the channel 120 , the gaseous or liquid substance is delivered to the balloon 126 through the opening 124 , allowing for the balloon 126 to expand to an inflated state, as shown in FIG. 3 . According to one embodiment, in its inflated state, the balloon 126 will have a diameter range of 0.1 to 3 cm.
[0025] FIG. 4 side presents a side elevational view of an alternative embodiment of the present invention. A catheter assembly 200 is of a diameter which allows the assembly to be inserted through a typical needle assembly and into the body of a patient. The catheter assembly 200 includes three portions: a central portion 204 , a proximal portion 206 and a distal portion 202 . The catheter assembly 200 is placed in the body of the patient with the distal portion 202 entering the body first.
[0026] The catheter assembly 200 includes an electrically conductive wire 216 that spans the length of the catheter assembly 200 . According to one embodiment, the wire 216 can be of helical nature with the same structure as described with reference to FIG. 2 a. At the central portion 204 of the catheter assembly 200 , a sheath 214 , formed from a thermoplastic or some other similar material, covers the wire 216 . The sheath 214 defines a central bore 212 through which a liquid may pass freely. According to another embodiment, where the wire 216 can be of helical nature, the electrically conductive wire 216 defines the central bore 212 .
[0027] At the proximal portion 206 of the catheter assembly 200 , the wire 216 is not covered by the sheath 214 and has a length that is shorter relative to central portion 204 of the catheter assembly 200 . The wire 216 is left exposed so that an electrical charge can make contact with it, in order to conduct an electrical charge down its entire length.
[0028] The distal portion 202 of the catheter assembly 200 also has a length that is shorter relative to central portion 204 of the catheter assembly 200 and is not covered by the sheath 214 . The wire 216 is left exposed at the distal portion 202 in order to allow the electrical charge to make contact with a target nerve. Attached to the wire 216 at the distal portion 202 is an electrically conductive tip 218 , which is a piece of rounded metal.
[0029] The catheter assembly 200 further includes a first inflatable balloon 226 that is located toward the distal end of the catheter assembly 200 , and a second inflatable balloon 232 that is located in the central portion 204 of the catheter assembly 200 . Both first inflatable balloon 226 and the second inflatable balloon 232 are shown in FIG. 4 in a deflated state. The second balloon 232 is located a distance of in a range of zero (0) to ten (10) cm from the first balloon 226 .
[0030] The first balloon 226 and the second balloon 232 can be expanded with either a gaseous substance or a liquid substance. A gaseous or liquid substance can be delivered to the first balloon 226 through a first balloon channel 220 , which terminates within the first balloon 226 , allowing for the gaseous or liquid substance to exit the first channel 220 through a first balloon channel opening 224 . The first channel 220 extends from the first channel opening 224 along the length of the central portion 204 and the proximal portion 206 of the catheter assembly 200 . At the proximal end of the first channel 220 is a first balloon channel injection opening 222 where the gaseous or liquid substance can be injected into the first channel 220 .
[0031] A gaseous or liquid substance can also delivered to the second inflatable balloon 232 through a second balloon channel 236 , which terminates within the second balloon 232 , allowing for the gaseous or liquid substance to exit the second channel 232 through a second balloon channel opening 234 . The second channel 232 extends from the second opening 234 along the length of the central portion 204 and the proximal portion 206 of the catheter assembly 200 . At the proximal end of the second channel 236 is a second balloon channel injection opening 238 , where the gaseous or liquid substance can be injected into the second balloon channel 236 . Once the gaseous or liquid substance is injected into the first balloon channel 220 or the second balloon channel 236 , the gaseous or liquid substance is delivered to the first inflatable balloon 226 through the first balloon channel opening 224 and to the second inflatable balloon 232 through the second balloon channel opening 234 . This allows for the first inflatable balloon 226 and the second inflatable balloon 232 to expand to an inflated state, as shown in FIG. 5 . According to one embodiment, in its inflated state, the first inflatable balloon 226 and the second inflatable balloon 232 will each have a diameter range of 0.1 to 3 cm.
[0032] The above described apparatuses may be used in numerous different medical procedures. The following described medical procedure is one type that utilizes the features embodied in the above described apparatus pertaining to FIGS. 1-3 . The method is drawn to the correct placement of the catheter assembly 100 , which once correctly positioned, allows for the administration of a continuous nerve block such as a local anesthetic agent. In particular, the following described method is directed to the administration of an interscalane nerve block, which is used to describe only one example of the utilization of the above described apparatuses for the administration of a continuous nerve block. It should be noted that the above described apparatuses may be used for any continuous nerve block, of which the interscalene block is one example.
[0033] The patient is positioned in the dorsal recumbent position with the head slightly in extension and turned somewhat to the opposite side. An assistant applies light traction on the arm with the elbow flexed. The interscalene groove is palpated in this position by the following procedure: First, the posterior edge of the clavicular head of the sternocleidomastoid muscle is located; then the palpating fingers are placed postero-lateral to this muscle to identify the interscalene groove. The external jugular vein almost always lies directly superficial to the interscalene groove and provides a useful additional landmark. Needle entry should be anterior or posterior to the vein. Another constant finding is that the interscalene groove is approximately 3 cm lateral to the most prominent portion of the belly of the sternocleidomastoid muscle at the level of the cricoid cartilage.
[0034] A typical needle assembly is inserted into the interscalene groove at the level of the cricoid (C6 level) and the needle is directed perpendicular to the skin in all the planes. For the placement of the catheter assembly 100 for this continuous interscalene nerve block technique, the needle assembly enters the skin at a point approximately halfway between the mastoid and the clavicle, posterior to the posterior border of the clavicular head of the sternocleidomastoid muscle.
[0035] The point of needle entry is just caudal to the accessory nerve and just posterior to the anterior border of the posterior triangle of the neck. The tip of the typical needle assembly continues until it penetrates the fascia sheath of the brachial plexus using ultrasound technology. At this point, the needle assembly is in direct contact with the brachial plexus and, according to one embodiment, the central stylet of the needle assembly is removed and the catheter assembly 100 is fed through the needle to a point just past the tip of the needle. According to another embodiment, the catheter assembly 100 is placed over the length of the needle assembly to a point just past the tip of the needle. Such a placement of the electrically conductive tip 118 is far enough so that the electrically conductive wire 116 does not make contact with the needle, i.e. the needle tip is in contact with the catheter sheath 114 which will not conduct (disperse) electricity.
[0036] The electrically conductive wire 116 is then charged with an electrical charge by making contact with the electrically conductive wire 116 with a nerve stimulator as is known in the art. The output of the nerve stimulator can be typically in the range of approximately 0.5-1.0 mA as the muscle twitching will increase because all the current is now concentrated in the electrically conductive wire tip 118 of the catheter assembly 100 . Once the catheter assembly is properly positioned, the inflatable balloon 126 is inflated in order to securely fix the catheter assembly 100 , which is done with the assistance of ultrasound technology, as the inflatable balloon 126 is visible on an ultrasound. For example, air or saline is injected into the balloon channel injection opening 122 , causing the air or saline to travel through the balloon channel 120 and to expand the inflatable balloon 126 to an inflated state (e.g. diameter of 5 mm).
[0037] Once the inflatable balloon 126 is fully expanded and the catheter assembly securely fixed, the typical needle assembly can then be removed and the local anesthetic may then be administered to effectuate a nerve block. When a dense motor and sensory block is required: (a) inject 20 mL of Ropivacaine 10 mg/mL (1%) as a bolus and then infuse with syringe driver a diluted concentration (5 mg/mL or 0.5%) at 10-20 mL/hour or (b) inject 20 mL of Bupivacaine 5 mg/mL (0.5%) as a bolus and then infuse a diluted concentration (2.5 mg/mL or 0.25%) at 10-20 mL/hour. When sensory block with minimal motor block is required: (a) inject 10-20 mL of Ropivacaine 2 mg/mL (0.2%) as a bolus and then infuse the same concentration at 1-10 mL/hour, continually adjusting the infusion rate to achieve the desired effect or (b) inject 10-20 mL of Bupivacaine 2.5 mg/mL (0.25%) as a bolus and the infuse the same concentration at 1-10 mL/hour, continually adjusting the infusion rate to achieve the desired effect. For Patient Controlled Interscalene Nerve Block, inject a bolus of 30 mL bupivacaine (0.4%) via an indwelling catheter into the brachial plexus sheath at the level of the interscalene groove followed by a background infusion of bupivacaine 0.15% at a rate of 5 mL/hour and a patient-controlled bolus of 4 mL for patients weighing>65 Kg and 3 mL for patients weighing<65 Kg.
[0038] In another embodiment of the present invention, a medical procedure utilizes the features embodied in the above-described apparatus pertaining to FIGS. 4-5 . The method is drawn to the correct placement of the catheter assembly 200 , which once correctly positioned, allows for the administration of a continuous nerve block such as a local anesthetic agent.
[0039] As described previously with respect to the medical procedure that utilizes the catheter assembly 100 , the patient is positioned in the dorsal recumbent position with the head slightly in extension and turned somewhat to the opposite side. An assistant applies light traction on the arm with the elbow flexed.
[0040] The interscalene groove is palpated in this position and a typical needle assembly is inserted at the level of the cricoid (C6 level) and the needle is directed perpendicular to the skin in all the planes. For the placement of the catheter assembly 200 for this continuous interscalene nerve block technique, the needle assembly enters the skin at a point approximately halfway between the mastoid and the clavicle, posterior to the posterior border of the clavicular head of the sternocleidomastoid muscle.
[0041] The point of needle entry is just caudal to the accessory nerve and just posterior to the anterior border of the posterior triangle of the neck. The tip of the typical needle assembly continues until it penetrates the fascia sheath of the brachial plexus using ultrasound technology. At this point, the needle assembly is in direct contact with the brachial plexus and the central stylet of the needle assembly is removed and the catheter assembly 200 is fed through the needle to a point just past the tip of the needle. Such a placement of the electrically conductive tip 218 is far enough so that the electrically conductive wire 216 does not make contact with the needle, i.e. the needle tip is in contact with the catheter sheath 214 which will not conduct (disperse) electricity.
[0042] The wire 216 is then charged with an electrical charge by making contact with the wire 216 with a nerve stimulator. Once the catheter assembly is properly positioned, the first inflatable balloon 226 is inflated in order to securely fix the catheter assembly 200 , which is done with the assistance of ultrasound technology, as the first balloon 226 is visible on an ultrasound. For example, air or saline is injected into the first balloon channel injection opening 222 , causing the air or saline to travel through the first balloon channel 220 and to expand the first balloon 226 to an inflated state (e.g. diameter of 5 mm). In another example, air bubbles or micro air bubbles are disposed within the assembly 200 allowing for inflation of the inflatable balloon 226 .
[0043] Once the first balloon 226 is fully expanded and the catheter assembly 200 securely fixed, the typical needle assembly can then be removed and the local anesthetic may then be administered to effectuate a nerve block. The first inflatable balloon 226 is then deflated and the second inflatable balloon 232 is inflated in order to maintain the catheter assembly 200 in place. The second balloon 232 is inflated in the same manner the first balloon 226 is inflated, where a liquid or gaseous substance is injected into the second balloon channel injection opening 238 , causing the liquid or gas to travel through the second balloon channel 236 , expanding the second inflatable balloon 232 to an inflated state (e.g. diameter of 5 mm). The first inflatable balloon 226 can also be inflated again in order to confirm that the catheter assembly is in the proper position via ultrasound.
[0044] The foregoing description of the specific embodiments so fully reveals the general nature of the invention that others can, by applying knowledge within the skill of the relevant art(s) (including the contents of the documents cited and incorporated by reference herein), readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present invention. Such adaptations and modifications are therefore intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. It is to be understood that the phraseology or terminology herein is for the purpose of description and not of limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan in light of the teachings and guidance presented herein, in combination with the knowledge of one skilled in the relevant art(s).
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The present invention is directed towards instruments and methods for discharging an anesthetic drug on a continuous basis for use as a nerve block. In accordance with the present invention, a catheter assembly is provided that comprises an electrically conductive wire, a protective sheath and an inflatable balloon. The inflatable balloon is at the distal end of the catheter capable of being inflated and deflated. A balloon channel terminates within the inflatable balloon at the distal end of the catheter and extends proximally along the length of the catheter to the proximal end of the catheter. The balloon channel has a balloon channel opening at a distal end of the balloon channel within the inflatable balloon, capable of releasing an injected substance into the inflatable balloon. The balloon channel further has a balloon channel injection opening at a proximal end of the balloon channel, capable of receiving an injected substance.
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A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
CROSS-REFERENCES TO RELATED APPLICATIONS
This application is related to, and incorporates by reference, the following U.S. patent applications filed on the same date as the present application: the application Ser. No. 08/082,678 entitled "Method and Apparatus for Trace Propagation in a Ring Network" filed by David C. Brief, Robert L. Macomber and James R. Hamstra, pending; the application Ser. No. 08/082,193 entitled "Elasticity Buffer Control Method" filed by James R. Hamstra and David C. Brief, pending; the application Ser. No. 08/083,111 entitled "Hybrid Loopback for FDDI-II Slave Stations" filed by David C. Brief, pending; and the application Ser. No. 08/083,963 entitled "Intelligent Repeater Functionality" filed by David C. Brief, Gregory DeJager, James R. Hamstra, pending.
BACKGROUND OF THE INVENTION
The present invention relates to communication networks, and more particularly to monitoring the link errors in communication networks.
A communication network includes a number of stations connected by communication links. The errors on a link are monitored so as to take a corrective action when needed. For example, in some Fiber Distributed Data Interface (FDDI) networks, a link is taken out of the network when the link error rate exceeds a predetermined threshold.
In particular, in some FDDI networks, link errors are detected by the physical layer of a station that receives data on the link. When a link error is detected, the physical layer generates an interrupt to a microprocessor controlling the SMT (Station Management) layer. The interrupts allow the microprocessor to keep track of the link errors. On each such interrupt, the microprocessor recomputes the link error rate and compares it to the threshold. If the link error rate exceeds the threshold, the microprocessor reconfigures the network to take the link out.
In high speed transmission networks, a station receives many bits per second (125 Mbits/second in the FDDI network). Hence, if even a small proportion of the received bits is erroneous, computing the link error rate and comparing it to a threshold may take a significant amount of the microprocessor time. The microprocessor becomes detracted from other tasks such as controlling the station MAC layer (MAC stands for Media Access Control) and other layers. It is therefore desirable to make link error monitoring more efficient so as to place less burden on the microprocessor.
SUMMARY OF THE INVENTION
The present invention provides in some embodiments an efficient link error monitor apparatus and methods that completely relieve the microprocessor from computing the link error rate and comparing it to a threshold. The link error rate computation and the comparison are performed by the physical layer. The physical layer generates an interrupt to the microprocessor only if a threshold is crossed and a microprocessor action may be required.
The physical layer includes a number of registers that can be conveniently written by the microprocessor to initialize the link error monitoring operation.
The physical layer computes the link error rate using a simply algorithm requiring only one register. On reset, this register is initialized to a positive number based on a link error rate prediction. Thus the register provides a realistic link error rate estimate even before any link errors are detected.
This initial estimate is also used in recomputing the link error rate when link errors are detected, but the initial estimate is given progressively smaller weight as more link errors are detected. The initial estimate thus helps obtain a realistic link error rate estimate when only few link errors have been detected.
Other features and advantages of the invention are described below. The invention is defined by the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partial block diagram of a communication station illustrating the use of the present invention.
FIG. 2 is a partial block diagram of a physical layer controller according to the present invention.
FIG. 3 illustrates a Link Event Monitor Event Register of the controller of FIG. 2.
FIGS. 4, 5a and 5b are pseudo-code representations of portions of the logic circuitry of the controller of FIG. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 is a block diagram of a portion of communication station 110 such as, for example, an FDDI communication station. Physical layer controller 120 transmits data to and receives data from a PMD (physical media dependent) transceiver. The transceiver, not shown, is connected to a transmission medium such as a fiber optics cable. Physical layer controller 120 performs the FDDI form 5 bit/4 bit data encoding and decoding, serial/parallel data conversion, clock recovery, clock generation, and link error monitoring.
Controller 120 is connected to isochronous MAC (Media Access Control) 130 and packet MAC 140. MACs 130 and 140 control access to the communication medium and perform address recognition, address generation, and verification of frame check sequences. The two MACs are connected to a higher level data layer (not shown). Software-operated microprocessor 150 controls the two MACs and the physical layer controller 120. See FDDI Physical Layer Protocol (PHY-2) American National Standard (ANSI X3.231-199X) incorporated herein by reference. See also Fiber Distributed Data Interface Designer's Guide (National Semiconductor Corporation of Sunnyvale, Calif., 1990) incorporated herein by reference.
Microprocessor 150 communicates with MACs 130, 140 and controller 120 through control bus (CBUS) 160.
Controller 120 detects link errors on the link on which the controller receivers data through the PMD transceiver. If the link error rate exceeds a predetermined "cutoff" threshold, the FDDI network is reconfigured to take the link out of the network. If the link error rate decreases and falls below a "pass" threshold, the link is re-inserted into the network. (Of note, when the link is taken out of an FDDI network, a continuous idle pattern is transmitted on the link which allows controller 120 to continue measuring the error rate on the link.)
In order to relieve the microprocessor from computing the link error rate and comparing it with the thresholds, controller 120 performs these tasks itself. Controller 120 interrupts the microprocessor only when the link error rate crosses one of the threshold under certain conditions that may require microprocessor intervention. These conditions are described below. The microprocessor and CBUS overhead are therefore reduced.
FIG. 2 is a partial block diagram of one embodiment of controller 120. Such a controller is described, for example, in DP83258/9 PLAYER-2S™ Enhanced Physical Layer Controller (National Semiconductor Corporation, 1992) incorporated herein by reference. In controller 120, phaser 210 recovers the 125 megahertz clock from the incoming data stream from the PMD transceiver. Phaser 210 generates a 12.5 MHz clock for synchronizing the controller operation.
Receiver 214 performs serial-to-parallel conversion of the incoming data and detects link errors. The receiver performs also other operations as described in the aforementioned document DP83258/9 PLAYER-2S™ Enhanced Physical Layer Controller.
Hybrid Multiplexer (HMUX) 220 performs the functions of an HMUX slave device as defined in the Hybrid Ring Control American National Standard (ANSI X3.186-199X) incorporated herein by reference.
Configuration switch 224 allows switching the transmitted and received data paths between one or more physical layer controllers and MACs.
Transmitter 230 performs serial-to-parallel data conversion and other operations described in the aforementioned document DP83258/9 PLAYER-2S™ Enhanced Physical Layer Controller.
Link error monitor (LEM) 234 includes threshold registers for representing link error rate thresholds. The use of such thresholds is described for example, in the FDDI station management American National Standard (ANSI X3.229-199X) incorporated herein by reference. LEM 234 also includes circuitry for continuously monitoring the link error rate and comparing it with the thresholds. The comparison is performed on every cycle of the 12.5 MHz clock. An interrupt to microprocessor 150 is generated whenever a threshold is crossed under certain conditions described below.
The threshold registers are writable by microprocessor 150 through CBUS 160 and CBUS control 232. CBUS 160 includes address and data buses thus providing a simple interface to LEM 234.
The link error rate (LER) is defined as the ratio of the number of error bits to the total number of bits received. Under the ANSI FDDI PMD standard, the maximum tolerable LER is 2.5×10 -10 . Thus in some applications, the pass threshold is 2.5×10 -10 or lower.
As is known, at the transmission speed of 125 Mbits/second, ##EQU1## where N is the number of link error bits in a time interval of T seconds. If T is the interval between successive error bits, then N=1.
LEM 234 estimates LER by computing T as a weighted average time interval AveInt between link errors. The highest weight is given to the most recent time interval between errors. More particularly, if i 0 , i 1 . . . i n are successive time intervals between errors, then ##EQU2##
Of note, the infinite sum of all the weights is equal to 1, i.e.,: ##EQU3##
Controller 120 computers AveInt and the intervals I 0 , . . . i n in cycles of the 12.5 MHz clock, that is, in the units of 80 ns. Using these units, we obtain from formula (1): ##EQU4##
In some embodiments, controller 120 does not detect all errors, and thus the actual LER can be higher than computer by controller 120. For example, in some FDDI embodiments, controller 120 detects only the following errors. In the ALS or CLS line states, a violation symbol is detected in the upper or lower nibble. In the ILS state, an error is detected if a symbol in either nibble is not Q, H or I and if successive nibbles do not form JK (the starting delimiter).
Controller 120 computers AveInt in an internal 48-bit register LERC. The logic equations for the controller 120 LEM circuitry are shown in Appendix A attached hereto. The equations are written in a language RTL easily understandable to persons skilled in the art. In RTL, assignments denoted by the symbol "=" are asynchronous assignments performed during the current clock cycle, and assignments denoted by "←" are synchronous assignments performed on the next rising edge of the clock. The clock is the 12.5 MHz clock generated by phaser 210.
LEM 234 includes register CLEIR holding the binary exponent of the number in register LERC. That is,
LERC=2.sup.CLEIR
Register CLEIR is designated as "lei -- bexp" in Appendix A. Register CLEIR is an 8-bit register. Its two most significant bits are unused. Register CLEIR is accessible from CBUS 160 which includes an 8-bit data bus.
LEM 234 computes the value of register CLEIR by determining the most significant "1" bit in register LERC. The mantissa of register LERC is discarded.
The following Table 1 shows the LEM registers accessible from the CBUS. Each register is an 8-bit register. CBUS 160 includes an address bus for addressing the registers. Register LERC is not accessible from CBUS 160 in some embodiments.
TABLE 1______________________________________Register Description______________________________________CLEIR Binary exponent of the interval between errors. The interval is stored in LERC.LECUTR Binary exponent of the cutoff threshold time interval between errors.LEPASR Binary exponent of the pass threshold time interval between errors.LEALR Binary exponent of the alarm threshold time interval between errors.LEMER LEM event register.LEMMR LEM mask register.______________________________________
Registers LECUTR, LEPASR, LEALR represent, respectively, the cutoff, pass, and alarm thresholds, The alarm threshold in a typical application is set between the cutoff and pass thresholds. When the alarm threshold is exceeded under certain conditions described below, an interrupt is generated to microprocessor 150 to alarm the user of a high error rate.
Each register LECUTR, LEPASR, LEALR is written with a binary exponent of the time-between-errors interval corresponding to the respective threshold. If LER -- THRESH is a link error rate threshold, equation (3) above provides: ##EQU5##
In some embodiments, when controller 120 is reset, registers LECUTR, LEPASR, LEALR are initialized, respectively, to the binary exponents of times-between-errors corresponding to the LER -- THRESH values 10 -7 , 2.5×10 -10 , 10 -9 .
The LER cutoff threshold is exceeded when the value in register CLEIR is below the value in register LECUTR. When the cutoff threshold is exceeded, controller 120 sets an internal flag LEM -- cutoff, signaling a Cutoff event. When register CLEIR has a value less than the value of register LEALR, controller 120 sets an internal flag LEM -- alarm, signaling an Alarm event. When the value of register CLEIR is equal to or greater than the value of register LEPASR, controller 120 sets an internal flag LEM -- pass, signaling a Pass event.
To avoid multiple interrupts when the link error rate is hovering around a threshold, the thresholds are "armed" so as to provide a hysteresis as follows. When the Cutoff event occurs, the pass threshold is armed and the alarm and cutoff thresholds are unarmed. Thus after the LER cutoff threshold is exceeded, cutoff and alarm threshold crossing does not generate an interrupt until the pass threshold is reached. When the Pass event occurs, the pass threshold is unarmed and the cutoff and alarm thresholds are armed so that respected occurrences of the Pass event will not generate an interrupt until the Cutoff or Alarm event occurs. When the Alarm event occurs, the pass and cutoff thresholds are armed and the alarm threshold is unarmed.
An armed event (i.e., crossing of an armed threshold) caused a bit to be set in LEM event register LEMER illustrated in FIG. 3. The bits of register LEMER are described in the following Table 2.
TABLE 2______________________________________Bit Symbol Description______________________________________D7 LEMAE LEM ALARM EVENT: This bit is set when an armed Alarm event occurs.D6 LEMCE LEM CUTOFF EVENT: This bit is set when an armed Cutoff event occurs.D5 LEMPE LEM PASS EVENT: This bit is set when an armed Pass event occurs.D4 LEMDE LEM DETECT EVENT: This bit is set when a Link Error Event is detected. A Link Error Event is an occurrence of a predetermined number of errors as defined by an LEM register writable by the microprocessor. See, for example, the description of the device PLAYER+ ™ in Desktop FDDI Handbook (National Semiconductor Corporation of Sunny- vale, California, 1992) incorporated herein by reference. This bit may be used in implementa- tions that want to time-stamp link errors and use an alternate LER algorithm.D3 LEMTE LEM THRESHOLD EVENT: This bit is set when the specified threshold number of events is reached. This bit may be used in implementations that use an alternate LER algorithm.D2:0 res Reserved for future use.______________________________________
When any one of bits LEMAE, LEMCE, LEMPE is set, controller 120 generates an interrupt to microprocessor 150 (unless the interrupt is masked as described below). Microprocessor 150 can then read register LEMER to determiner which event has occurred. The microprocessor can then write register LEMER to reset the register. When a bit of register LEMER becomes set, microprocessor 150 is prevented by controller 120 from writing the register LEMER until the microprocessor reads the register. This prevents the microprocessor from overwriting the register LEMER before detecting that a register bit has been set.
LEM mask register LEMMR has one bit for each bit of register LEMER to mask the corresponding interrupt. For example, if bit D7 of mask register LEMMR is reset, an interrupt is not generated when bit D7 of register LEMER is set.
Bits D2:0 of register LEMMR are reserved for future use just as bits D2:0 of register LEMER.
FIG. 4 illustrates in pseudo-code some logic operations performed by LEM 234 on reset. Register LERC is initialized to the value of the 48-bit register PASEXP. Register PASEXP holds the pass threshold time interval between errors, that is,
PASEXP=2.sup.LEPASR (4)
Register LERC is initialized to PASEXP rather than to zero for the following reasons. The initial value of LERC corresponds to the time interval i 0 of formula (2). Interval i 0 is given the weight of 1/2 n+1 where n+1 is the number of detected link errors. Thus when the number of detected errors is small, the interval i 0 is given a large weight. If register LERC were initialized to zero, register LERC would not provide as accurate estimate of the link error rate until a large number of errors were received, except for systems where the link error rate is very large, that is, where the average time interval between link errors is close to zero. Since in most networks the average time interval is closer to the pass threshold time interval than to zero, initializing the register LERC to the pass threshold time interval allows obtaining a realistic estimate of the actual link error rate immediately upon reset or at least after detecting but a small number of link errors.
In some embodiments register LERC is initialized on reset to another positive value. This value is greater in some embodiments then the cutoff threshold time interval between errors. In some embodiments, this value is greater than the alarm threshold time interval between errors.
As shown in FIG. 4, register CLEIR receives the binary exponent of the value in register LERC.
Flag arm -- pass is reset (receives the value zero) so that the Pass event is unarmed. Flags arm -- cutoff and arm -- alarm are set so that the Cutoff and Alarm events are armed.
FIGS. 5a, 5b show in pseudo-code some logic operations performed by LEM 234 after reset on every rising edge of the 12.5 MHz clock. If a new link error has not been detected, register LERC is incremented, and if a new link error has been detected, the contents of register LERC are shifted right to divide the register by two. The reason for these operations is as follows. If the value AveInt after the receipt of n+1 errors is denoted AveInt n , then formula (2) above shows that:
AveInt.sub.n =1/2(i.sub.n +AveInt.sub.n-1) (5)
When a new link error is not detected, register LERC is incremented so that register LERC during an error-free interval i n becomes increased by i n . When a new error is detected, register LERC is divided by two to obtain AveInt n .
As shown in FIG. 5a, register CLEIR receives the binary exponent of register LERC.
Register CLEIR is compared with the three thresholds to determine whether a bit should be set in LEM event register LEMER. If the Alarm event is armed (arm -- alarm=1) and the value of register CLEIR is smaller than the value of register LEALR, then (1) the LEMAE bit of the LEM event register is set indicating the Alarm event; (2) the Pass and Cutoff events are armed (flags arm -- pass and arm -- cutoff are set); and (3) the Alarm event is unarmed (flag arm -- alarm is reset). If the Cutoff event is armed and CLEIR is less than LECUTR, then the LEMCE bit of register LEMER is set, the Pass event is armed and the Cutoff and Alarm events are unarmed. If the Pass event is armed and register CLEIR is greater than or equal to register LEPASR, then the LEMPE bit of register LEMER is set, the Pass event is unarmed and the Cutoff and Alarm events are armed. An interrupt is then generated in accordance with the values of registers LEMER and LEMMR.
As is seen from the above, LEM 234 determines whether the link error rate crosses a threshold, and if the interrupts are not masked, LEM 234 interrupts the microprocessor when: (1) the Pass event is armed and the link error rate LER crosses the pass threshold in the downward direction, that is, LER changes from a value larger than the pass threshold to a value equal to or below the pass threshold; (2) the Alarm event is armed and LER crosses the alarm threshold in the upward direction; or (3) the Cutoff event is armed and LER crosses the cutoff threshold in the upward direction.
While the invention has been illustrated with respect to the embodiments described above, other embodiments and variations are within the scope of the invention. In particular, the invention is not limited to register sizes or bus widths. Further, the invention is not limited to any particular clock rate or to any particular operations being performed on a particular edge or a particular cycle of a particular clock. In some embodiments, the Pass event is defined as the event that LER is less than the pass threshold rather than less than or equal to the pass threshold. In some embodiments, the Alarm event is defined as the event that LER is greater than or equal to the alarm threshold. In some embodiments, the Cutoff event is defined as the event that LER is greater than or equal to the cutoff threshold. Other embodiments and variations are within the scope of the invention as defined by the following claims. ##SPC1##
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In a communication network, an efficient link error monitor is provided that completely relieves the microprocessor of computing the link error rate and comparing it with link error rate thresholds. The link error rate computation and the comparison are performed by the physical layer of a communication station. The physical layer generates an interrupt to the microprocessor only if a threshold is crossed and a microprocessor action may be required. The physical layer includes a number of registers that can be conveniently written by the microprocessor to designate the thresholds and monitor the link errors. The link error rate is estimated using a simple estimator that provides a realistic link error rate estimate even at early stages of operation when few link errors have been detected and when, therefore, little statistical information on the link error rate exists.
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CROSS REFERENCE TO RELATED APPLICATION
This is a continuation of co-pending application Serial No. 07/020,541, filed Mar. 3, 1987 now abandoned.
BACKGROUND OF THE INVENTIONS
This invention relates to a process for monitoring the tightness of packs disposed in a measuring chamber. The invention also relates to an arrangement for carrying out this process.
Arrangements for the non-destructive testing of flexible packs for leaks are already known. German Utility Model G 8 128 651 describes one such arrangement comprising a measuring chamber designed to receive the sample to be tested and a feeler in said chamber which is sensitive by contact to variations in pressure and which is connected to a calculator for recording the variations in pressure as a function of time. The disadvantages of an arrangement such as this are that the measuring cells are disposed in the measuring chamber which necessitates careful handling in view of the fragility and sensitivity of the measuring cells. On the other hand, since the feeler is only sensitive by contact, high sensitivity of measurement cannot be expected in view of the risks of unevenness of the sample to be measured. Finally, this known arrangement can only be used for testing flexible packs.
Other arrangements for detecting leaks in rigid objects or packs are also known. The system according to U.S. Pat. No. 2,467,767 comprises a measuring chamber which operates under excess pressure and which is equipped with liquid manometers. The entire system is manually controlled without any automation. All the pressure values have to be acquired by successive observations on the part of the operator who deduces the nature of any leaks therefrom by comparison. The principal limitation of this known process in regard to microleaks is that it is difficult to evaluate the small difference between the values successively read off from the manometer connected to the test chamber, the range of measurement of this manometer being at least equal to the total pressure of the fluid contained in the chamber. As a result, the reliability of the measurements depends upon human parameters, i.e., upon the quality of the observations of the operator. Finally, U.S. Pat. No. 2,467,767 does not make any reference to tests under reduced pressure and is not designed to be used for the detection of leaks in non-rigid objects or packs.
U.S. Pat. No. 3,331,237 describes a system having improved sensitivity through the use of a differential manometer. Unfortunately, this known system is only applicable to solid objects comprising an internal cavity capable of being connected to the measuring equipment by a connecting hose. Accordingly, it cannot be applied either to packs, such as flexible bags, or to rigid packs containing products, connection without destruction of the pack being impossible.
U.S. Pat. No. 3,504,528 describes a system which is also based on differential measurement, the comparison being made between two chambers, namely a measuring chamber and a reference chamber. These two chambers are symmetrically inserted into two circuits connected in parallel from a first chamber initially charged with a gas under pressure. This known system is only applicable to solid objects, such as non-deformable shell cases, and the test can only be carried out under excess pressure. Another disadvantage of this known system lies in the permanent connection of the differential sensor to the two chambers which can lead to overloading of the allegedly very sensitive sensor unless the valves are perfectly synchronized or in the event of a sudden leak in one of the chambers.
Publication Wo 81/01 333 claims an arrangement which is based on the transfer of predetermined quantities of a gas, the differential measurement of the pressure being effected by comparison between two branches which are symmetrical in volume or at least proportional to one another. Intended according to the author for monitoring objects of defined shape comprising a cavity it is desired to test for leaks, this known arrangement is not designed to be applied to flexible bags containing a product, for example, a powder, of which the shape and the volume vary according to the pressure applied and the quantity of gas contained in the bag, these variations being capable of reaching significant proportions without common measurement with those emanating from the manufacturing tolerances of a solid object to the shape of which the measuring chamber is adapted. In addition, this known arrangement has the disadvantage of necessitating the modification of at least two volumes or chambers in the event of a change in the dimensions of the object to be tested.
In addition, the pressures in the system depend upon the feed pressure, for which no regulating or measuring arrangement is provided, so that the detection of a major leak in the described process is rendered uncertain.
SUMMARY OF THE INVENTIONS
The object of the present invention is to provide a measuring process and an arrangement for carrying out this process which enable the disadvantages and limitations of the prior art to be overcome.
Accordingly, the present invention relates to a process for monitoring the tightness of packs disposed in a system comprising a section including means for adjusting the pressure and at least one reservoir and a section including a measuring chamber for the pack to be monitored, in which a predetermined pressure p1 is established in the section including the means for adjusting the pressure, the section under the pressure p1 is placed in communication with the section containing the closed measuring chamber to arrive at a pressure p2, the section which contains the measuring chamber is isolated from the which does not contain the measuring chamber and the differential pressure δp between these two sections is measured over a predetermined period by means of a differential pressure cell placed between said measuring chamber and said reservoir. The reservoir serving as pressure reference, although its volume is independent of that of the measuring chamber.
If the pressure p2 is sufficiently close to the pressure p1, in other words if the dead volume in the measuring chamber containing the pack is sufficiently small, the detection and display of leaks are effected at the pressure p2 throughtout the system.
By contrast, in cases where p1 is very different from p2, it is preferable to restore the pressure throughout the system to its initial value p1 and then to effect measurement of the leak in the pack in question.
The means for adjusting pressure may operate both under reduced pressure and under excess pressure.
The object of the process according to the invention is the non-destructive testing and measurement of the tightness of flexible, semi-rigid or rigid packs capable of containing products in the form of powders, granules, pastes or liquids, the test preferably being carried out under reduced pressure for flexible packs and generally under excess pressure for rigid packs containing liquid products.
Intended for industrial application, the process according to the invention is based on an essentially automatic concept which does not rely on the judgement of the operator, the acceptance or rejection criteria being constituted by predetermined parameters introduced as data into the electronic circuits of the measuring system, the results of the tests and measurements optionally being automatically recorded to derive a statistic or other subsequent treatment therefrom. A modified embodiment comprises a graphic recorder for the variation in pressure and adders to account for the result of the tests. To this end, the pressure and time parameters are present electrically according to the type of pack to be monitored.
When applied to production control, the process according to the invention may be used both for sampling and for the systematic examination of all the packs. The object of the process is thus to identify the various hazards of production, such as major leaks, microleaks, the possible absence of product in the pack and even the absence of the packs itself during a measurement.
The absence of a pack, major leaks in the pack and any faults in the tightness of the measuring chamber are detected by means of the differential pressure cell. In the case of flexible packs, leaks are monitored in a measuring chamber adapted in its shape to the pack in order to limit the deformation thereof. The process comprises enclosing the object to be tested in a tight chamber equipped with a detachable cover in which the pressure is initially adjusted to a predetermined value, subsequently measuring the development of this pressure by comparing it automatically with pre-established reference values, the initial value of this pressure being higher or lower than that prevailing in the pack in its free state, the reference values being experimentally determined according ot criteria, specific to each type and size of pack, quantifying the various possible states thereof. The measuring time is normally between 2 and 20 seconds, depending on the pack to be tested. The pressure is also dependent on the sample to be tested and is generally between 100 and 450 torr where measurement is carried out under reduced pressure. In the case of 100 g bags containing soluble coffee, it is preferred to maintain a reduced pressure below 275 torr because otherwise the bag would crack at the folds.
Where excess pressure is applied, the value of p1 is of the order of 1 bar.
The present invention also relates to an arrangement for carrying out this process, comprising the following components connected in line by conduits:
a means for adjusting the pressure,
an electrovalve V1 acting as actuator to requlate the pressure p1,
a reservoir of volume X1 independent of that of the measuring chamber,
a relative pressure cell pA,
an electrovalve V3 for separating the section comprising the reservoir from the section comprising the measuring chamber,
an electrovalve V4 at the ends of which a differential pressure is measured by
differential pressure cell pB and
a measuring chamber designed to receive the pack, said chamber comprising a cover by which it can be opened and closed.
Other features will become apparent from the accompanying drawings. The arrangement according to the invention also comprises an electronic device for the introduction and storage of pressure and time parameters, the sequential control of the electrovalves, the control of the pressure in the reservior, the display of the measurement results and their presentation for recording and/or for processing by an outside terminal.
The process according to the invention will be better understood after the description of one example of embodiment of the arrangement intended to carry it out without being considered as in any way limitative.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 diagrammatically illustrates the arrangement according to the invention designed to operate under reduced pressure.
FIG. 2 is a more detailed illustration of the measuring chamber shown in FIG. 1.
FIG. 3 shows part of the arrangement of FIG. 1 with a measuring variant for Δp.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As shown in FIG. 1, the arrangement comprises a vacuum pump p fed by the mains (not shown) and connected to the entire system by conduits (1). Between the vacuum pump p and the measuring chamber (2), there is a valve V1 for controlling the level of the vacuum in the arrangement, a reservoir E1 of volume X1 and valves V2, V3, V4 and V5 of which the functions will be explained hereinafter. In addition, connected in parallel relative to the principle circuit between the valves V2 and V3 is a measuring cell PA for measurement and regulation by servo control of the pressure in the arrangement in conjunction with at least the valve V1.
A further, secondary chamber E2 of volume X2<X1 is readily connected in parallel. The presence of these two reservoirs E1 and E2 enables packs of very different volume to be measured without any need for particular adaptation of the volumes X1 and X2, the chamber X2 performing hardly any function in the measurement of the leaks themselves.
The differential measuring cell PB connected in parallel with the valve V4 provides for very sensitive measurement of the difference in the pressures upstream and downstream of that valve when it is closed. It is this cell which will be used for measurement of the development of the pressure in the measuring chamber.
The valves V6 and V7 are directly connected to the pump P and, as will be explained hereinafter, enable the measuring chamber (2) to be opened and closed by raising or lowering of the cover (8) in relation to the base (6).
At the level of the measuring chamber (2), the detector (3) serves as an end-of-travel marker during the closure of said chamber to enable the process to continue.
Each of the valves V1 to V7 comprises an induction coil B1 to B7 electrically connected by connections (15) to the electronic control unit (4) which comprises the sequential program for the opening and closing of the electrovalves.
The electrovalves may be of any standard commercial type and will not be described in any more detail here.
The pressure measuring cells PA and PB are also electrically connected by connections (16) to the electronic control unit (4).
The pressure measuring cells PA and PB may also be of any standard commercial type, whether piezo-electric, inductive, resistive or capacitive, and give a signal proportional to the pressure to be measured. It is merely pointed out that the cell PA should have a range at least equal to the pressure used whereas the differential cell PB may highly sensitive. As shown in FIG. 1, the cell PA may readily be of the differential type, one of its inputs being in the open, thus giving a measurement of the relative pressure in the system, which is negative in the present case or positive where the system operates under excess pressure, and connected to a device which generates gas or air under pressure instead of the vacuum pump P.
It can be seen that the arrangement of the pneumatic circuit from the pump P to the measuring chamber (2) is substantially linear, only the auxiliary circuit for controlling the closure piston being connected in parallel.
In one preferred embodiment, the electronic control unit (4) comprises a small, programmable automatic logic device optionally comprising a microprocessor, of which numerous types are commercially available, an analog section for amplifying the signals coming from the sensors and for displaying the measurements they represent in analog form, an analog-digital converter for digital display and a group of circuits making the comparison with reference values previously displayed and memorized by means for potentiometers or through a keyboard or even digital switches.
Since circuits of the type in question are familiar to the man skilled in the art, it is not intended to describe them in any more detail here, nor have they been shown, unless to specify that the measured values and the result of the comparisons described hereinafter are also available in electrical form to serve as input values for a recorder and to actuate the adders or any other means for recording the results outside the arrangement according to the invention.
As shown in FIG. 2, the measuring chamber (2) comprises a fixed element (6) which is mounted on a frame (5) and which is designed to receive the samples (7) to be tested. The conduit (1) extends to the measuring chamber (2) which additionally comprises a displaceable element (8) fixed to a cylinder (10) and piston (11) system and comprising guides (9). The measuring chamber is opened and closed, i.e., the displaceable element (8) is displaced, under the effect of vacuum and atomospheric pressure on either face of the piston (11). Finally, the chamber comprises at least one seal (12). The measuring chamber may also be opened and closed by means of a cover (8) which is not displaceable, but instead is designed to pivot or tilt about an axis. The speed of movement of the cover may be limited by the addition of throttles between V6, V7 and the piston or at the "open air" outlets of said valves.
The operation of the arrangement according to the invention as described hereinafter is not intended to be interpreted in a limitative sense insofar as features both of the process and of the arrangement according to the invention are mentioned.
A vacuum is established by means of the pump P up to the initially closed valve V3, the valves V1, V2 and V4 being opened and the valve V5 closed. The reduced pressure obtained, which is measured by the cell PA, is displaced on the electronic control unit and compared with a preset value p1. When this value is reached, the valve V1 is closed and remains closed unless it is desired to change the value of p1 between the various phases of the test and measuring process.
In addition, the reduced pressure supplied by the vacuum pump is used to open or close the measuring chamber as and when necessary through the three-way valves V6 and V7 shown in FIG. 1.
To ensure that the measuring chamber is open before any measurement, the valve V6 is opened to establish a vacuum in the section A (FIG. 2) while the valve V7 is closed so that atmospheric pressure prevails in the section B (FIG. 2), the displaceable section (8) thus moving into its upper position while the section B is at atmospheric pressure via the channel 13 of the valve V7. The sample (7) is then placed in the measuring chamber. The valve V7 is opened to establish the vacuum in the section B while the valve V6 is closed to return the section A to atmospheric pressure via the channel 14.
The electrovalves V1, V6 and V7 remain in the above-mentioned states for the rest of the test. The piston (11) moves downwards to the end-of-stroke detector (3). The sample (7) is now ready to undergo the tightness test.
Before the tightness test, the measuring chamber is checked as follows for any leaks, for the presence of the sample and for any major perforation thereof: if the sample is small in size, the valve V3 is opened and the valve V2 is closed so that only the chamber E2 is in use. If the sample is relatively large in size, the valves V2 and V3 are opened so that both the chambers E1 and E2 are in use. A pressure p2>p1 is established throughout the system. The value Δp=p2-p1 is compared as described hereinafter with three threshold values p3, p4 and p5 to determine on the one hand whether the sample is absent or seriously perforated and, on the other hand, whether the measuring chamber is untight. The arrangements intended solely for measuring packs of relatively large dimensions do not require the use of the reservoir E2. The reservoir may thus be omitted, the same also applying to the electrovalve V2.
Because this preliminary check is rapidly completed, the actual tightness test may be carried out by closing the electrovalve V4, thus isolating the measuring chamber from the rest of the pneumatic circuit.
The cell PB then measures the difference in pressure δp between the measuring chamber and the section comprising the reservoir of which the pressure p2 serves as reference.
This pressure difference, which is zero at the moment of closure of the electrovalve V4, will or will not remain zero depending on whether or not the sample is tight. The value of δp can be seen on the display part of the electronic control unit (4) and may be recorded on a standard graphic recorder.
As described above, the electronic control unit then compares the valve of δp with a pre-established limit value characterizing the acceptable degree of tightness.
On completion of the measurement, the valve V5 is opened to break the vacuum in the measuring chamber. To open the measuring chamber, V6 is opened to establish a vacuum in A while the valve V7 is closed to return B to atmospheric pressure via the channel 13. The piston (11) moves upwards. The arrangement is now ready for another measurement.
The two main measuring phases of the process are described in more detail hereinafter for operation under reduced pressure.
The principal phase of these two main measuring phases comprises measurement of the actual microleaks, the other being concerned with verification of the presence of a pack and of the absence of major leaks.
The pressure in the reservoirs E1 and E2 having been adjusted as described to a certain predetermined value p1 experimentally selected for a given type of pack and the measuring chamber having been closed, likewise the valve V5, the electrovalves V3 and V4 are opened.
A new pressure value p2 is established in the system as a function of the transfer of gas between the measuring chamber and that part of the circuit comprising the reservoirs E1 and E2.
All other things being equal, the difference Δp=p2-p1 will be approximately proportional to the volume of air contained in the chamber and hence to the difference between the volume of the chamber and the initial volume of the pack. Accordingly, it is obvious that the absence of a pack will produce a difference Δp greater than that obtained with a tight pack of which the volume is not freely expandable. It is thus possible electrically to compare the difference Δp between the succesive values p1 and p2 of the pressure with a reference threshold p3 pre-established by calculation or by experiment for a given pack.
The same applies in the event of a major fault in the tightness of the pack, although in that case the difference Δp is smaller because part of the volume is occupied by the packed product. It is thus possible to compare the difference Δp with a reference threshold p4, the criterion for a seriously perforated pack, of which the value is also experimentally determined by intentionally placing a perforated pack in the chamber. The value thus determined is readily corrected by a small safety margin before being introduced as parameter into the electronic control unit (4) in order to take into account small differences in the dimensions or in the filling of the packs. Finally, a leak between the cover (8) and the base (6) at the seal (12) will produce an even greater pressure difference. When the system returns to amospheric pressure, a threshold p5 is exceeded.
Since calculation of the difference between the pressures p1 and p2 is not necessarily easy in the case of small differences, FIG. 3 shows by way of Example a preferred embodiment which enables Δp to be directly measured by means of the differential measuring cell PB, utilizing the high sensitivity thereof.
Compared with the arrangement shown in FIG. 1, this preferred embodiment additionally comprises a valve V8 together with its induction coil B8 and a chamber E3 of small volume X3. Initially, the valves V3, V4 and V8 are closed. V4 is opened, followed by V3. The chamber E3 is thus at the pressure p1. V4 is closed, after which V8 is opened, the pressure p2 being established in the chamber E3 and at one of the inputs of the cell PB, the other input remaining at the pressure p1. It is thus possible directly to display Δp on the electronic control unit (4) and to compare its value with the threshold values introduced beforehand, for example, by display on the potentiometers.
Alternatively, the above test may be carried out without V3 or V8 by reclosing V2 and opening V3 and V4. The reservoir E2 and the measuring chamber (7) and thus at a pressure p2. V4 is then closed and V2 opened. The cell PB measures a pressure difference Δp'=p2-p1', p1' being a value similar to p1 where X2<<X1.
Then, if the pressure p2 or p1' is sufficiently close to p1, in other words if the dead volume in the measuring chamber containing the pack is sufficiently small, the detection of leaks and their display are carried out at the pressure p2 in the system.
By contrast, if p1 is very different from p2, it may be preferable to restore the pressure throughout the system to its initial value p1 before the pack in question is measured for leaks.
The measurement of a pack for leaks is then carried out by isolating the part containing the chamber from the part comprising the reservoirs after the electrovalve V 4 has been opened for a brief instant and then closed again.
These are now two possibilities: if the pack is tight, the pressures will remain stable throughout the system, the value δp measured by the cell PB is zero and remains zero.
If, by contrast, the pack is perforated, the pressure in the measuring cell is increased by the escape of air from the pack. This results in a variation dδp/dt and hence, after a certain time, in a pressure difference δp at the inputs of the cell PB.
The electrical analog signal corresponding to the value of δp and hence proportional to the leak may thus be recorded in a graphic form and simultaneously displayed on an instrument and even compared with a threshold value, the analog display being readily implemented on an instrument comprising a scale of 200%, the value 100% corresponding to the acceptability threshold or limit of tightness.
The criterion of acceptance of the pack, which corresponds to the maximum value of the admissible microleak, may be electronically fixed in the form of a comparison threshold for δp of usually from O to 50 torr relating to the variation in pressure over a predetermined period, for example of 2 to 60 seconds, for a fixed value of p1. These parameters then remain valid for the type of pack in question.
It is obvious that the electronic circuit could also use the criterion dδp/dt by differentiation, although this would be less easy.
In addition, it should be pointed out that the test and measuring operations have to take place relatively quickly not only for reasons of productivity, but also because the quantity of air or gas contained in the pack is limited. The measurement of δp should also be effected while a sufficient pressure difference prevails between the interior of the pack and the measuring chamber. For the same reasons, the measuring chamber should comprise as small a dead volume as possible to ensure maximal sensitivity of measurement. Accordingly, it should be adapted to the shape of the samples to be measured either during its production where it is designed for a single type a pack or by adaptation of additional filling elements where it is designed to accommodate samples of different shape.
The foregoing explanation also shows that the volume of the reservoirs E1 and E2 has no bearing on the measurement of δp. The only requirement for this measuring phase is that the pressure in the reservoirs should remain stable because it acts as a reference to the cell pB.
Practical experience confirms the obvious reasoning that it is sufficient for the reservoir E1 to be large enough to allow an adequate reduced pressure in the measuring chamber, for example 500 torr, without any loss of pumping time through V1.
Since the pack initially contains a certain volume of gas under a certain pressure, its confinement in a tight chamber subjected after closure to a pressure different from atmospheric pressure will produce an elastic deformation if the material is flexible or semirdigid or an expansion or compression, depending on whether the pressure applied to the measuring chamber is above or below atmospheric pressure. Except in the case of an infinitely deformable bag, a pressure difference will nevetheless be created between the pack and the dead volume of the chamber, persisting or developing according to the degree of tightness.
In the case of a particularly flexible pack, such as a flat bag, its surface will ultimately come into contact with the upper and lower faces of the chamber of which the dimensions--as was seen earlier--have to be kept as small as possible to limit the dead volume.
This particular case is shown in FIG. 2, the upper face of the chamber merely being the flat face of the cover.
Study of the sequence of measurement of the leaks shows that the preliminary check is essential because a seriously perforated pack or the absence of a pack does not produce any variation δP.
The complete test is normally over in a few seconds.
The phases of measurement of the microleaks and of checking for the presence of samples, their non-perforation and the tight closure of the chamber may be reversed.
In order to save time, the checking phase may even be omitted if leakage measurement gives a result which falls within certain predetermined limit values.
For example, the checking phase need only carried out if the measured leak is zero or substantially zero which may indicate that the sample is seriously perforated or absent or even when the leak is very considerable which may indicate that a cell has not been properly closed or that a seal is not tight.
All that has been said in the foregoing for an arrangement operating under reduced pressure is also applicable where the arrangement operates under excess pressure, i.e., with a compressor, a compressed gas cylinder or any other suitable means.
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The tightness of sealed packages is monitored by means of a process and an apparatus system which utilize and incorporate a first system section, which includes at least one reservoir and a pressure measuring cell, a second system section, which includes a rigid measuring chamber, and means for adjusting pressure of the system sections via the first system section. The first system section is first pressurized to a predetermined pressure, which may be either above or below atmospheric pressure, and then the first and second system sections are brought into communication for establishing a second pressure for the first and second system sections combined. Major leaks in the sealed packages, absence of a sample in the measuring chamber and leaks in the measuring chamber then may be detected with the aid of the pressure measuring cell. For detecting other than major leaks, the first and second system sections then are isolated and a differential pressure cell detects the pressures of the first and second system sections for a timing sufficient to detect differences in pressure between the first and second system sections for detecting if the package being tested has leaks.
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The present application claims priority under 35 U.S.C. 119 and 35 U.S.C. 365 to Korean Patent Application No. 10-2005-0 133183 (filed on Dec. 29, 2005), which is hereby incorporated by reference in its entirety.
BACKGROUND
A Merged Memory Logic (MML) device may be a device including a Dynamic Random Access Memory (DRAM) and peripheral circuits integrated on a single chip.
MML has improved the functionality of multimedia and may allow high-integration and high-speed operation of a semiconductor device to be more effectively achieved. In addition, in the field of an analog circuit requiring high-speed operation, a semiconductor device having a mass storage capacitor is being developed.
A capacitor may have a Polysilicon-Insulator-Polysilicon (PIP) structure. In such a situation, a top electrode and a bottom electrode may include conductive polysilicon.
However, a capacitor having such a PIP structure may have various disadvantages. For example, a capacitance may be lowered because natural oxide layers may be formed due to an oxidation reaction occurring at the interfacial surface between the top/bottom electrodes and a dielectric thin film.
Further, due to a depletion region that may be formed in a polysilicon layer, a PIP capacitor may have a lowered capacitance and thus may be unsuitable for high-speed and/or high-frequency operation.
A MIM type capacitor, on the other hand, may be used for high performance semiconductor devices. It may have low resistivity and may not cause parasitic capacitance derived from the depletion.
FIGS. 1A and 1B are example cross-sectional diagrams to illustrate a related art semiconductor and method for fabricating a semiconductor device having an MIM capacitor and a damascene interconnection structure.
Referring to FIG. 1A , first metallic interconnection 15 and second metallic interconnection 20 may be formed on bottom insulating layer 10 of semiconductor substrate 1 . First and second metallic interconnections 15 and 20 may not form a step difference relative to bottom insulating layer 10 .
A metallic layer may be formed on a resultant structure where first metallic interconnection 15 and second metallic interconnection 20 are formed. The metallic layer may be patterned, and may form bottom electrode 25 of a capacitor making contact with a top surface of second metallic interconnection 20 .
Dielectric layer 30 may be formed on a resultant structure including bottom electrode 25 . Another metallic layer may then be formed on dielectric layer 30 , and may be patterned such that top electrode 35 of the capacitor is formed, for example at a position corresponding to bottom electrode 25 . Interlayer dielectric layer 40 may be formed on a resultant structure where top electrode 35 may be formed.
Referring to FIG. 1B , a top surface of interlayer dielectric layer 40 may be planarized, for example by a CMP process. Then, interlayer dielectric layer 40 and dielectric layer 30 may be etched, for example to form via hole V 1 that may expose a top surface of first metallic interconnection 15 .
First trench T 1 may be formed on a top of via hole V 1 . Second trench T 2 , that may expose a top surface of top electrode 35 , may be formed. Via hole V 1 and first and second trenches T 1 and T 2 may be filled with Cu. A CMP process may then be performed with respect to Cu, and may thereby form a damascene interconnection structure 45 and contact plug 50 .
The above described technique may have various problems. For example, a metallic interconnection process for applying a bias voltage to a bottom electrode of the capacitor may be necessary, and a process may become more complex because the via hole and the trench of the top electrode may not be able to be simultaneously formed.
In addition, capacitors may increasingly be important components in a structure of a logic device. Hence, there may be a technical need to improve a capacitance of a capacitor.
There may be several methods for maintaining and/or increasing a capacitance of a capacitor at an appropriate value in a limited unit area, as expressed by the equation C=∈As/d (∈: dielectric constant, As: surface area of electrode, d: thickness of dielectric element). Some of the suggested methods include reducing a thickness of a dielectric element, increasing a surface area of a electrode, and using a material having a high dielectric constant ∈.
With respect to increasing a surface area of an electrode, a related art analog capacitor may use a metallic interconnection as top and bottom electrodes. Accordingly the effective surface area of the related art analog capacitor may be formed as a plane. Hence, there may be a limitation regarding increasing a surface area of the electrode.
FIGS. 2A to 2E are example cross-sectional diagrams to illustrate a related art method for fabricating a semiconductor device having a capacitor and a contact plug between interlayer interconnections.
Referring to FIG. 2A , interlayer dielectric layer 2 may be formed. Metallic conductive layer may be formed and patterned on a top of interlayer dielectric layer 2 such that bottom electrode 4 A and bottom interconnection 4 B may be formed. A semiconductor substrate (not shown), on which the semiconductor device may be formed, may exist under interlayer dielectric layer 2 .
Inter-metallic dielectric layer 6 may be formed and planarized on bottom electrode 4 A and bottom interconnection 4 B.
Referring to FIG. 2B , contact hole 8 that may expose bottom electrode 4 A of the capacitor may be formed by using a known photolithographic process.
Contact hole 8 , that may expose bottom electrode 4 A, may constitute an effective surface area of the capacitor, so the capacitor may have a large effective surface area.
Referring to FIG. 2C , dielectric layer 10 may be formed on a surface of the substrate including contact hole 8 .
Referring to FIG. 2D , via hole 12 , that may expose bottom interconnection 4 B, may be formed, for example using a known photolithographic process.
Referring to FIG. 2E , a top interconnection conductive layer may be formed and patterned on a surface of semiconductor substrate, and a form top electrode 14 A and top interconnection 14 B of the capacitor.
The MIM capacitor as described above may be limited as to an increase in capacitance of the capacitor because the effective surface area of the capacitor is formed as a plane.
SUMMARY
Embodiments relate to a semiconductor device having a capacitor, and a method of fabricating a semiconductor device having a capacitor. Embodiments relate to a semiconductor device having a capacitor and a method of fabricating the same, that may be capable of simplifying the manufacturing process and increasing a capacitance of the capacitor.
Embodiments relate to a capacitor that can be simultaneously formed with a contact plug for applying a bias voltage to a bottom electrode through a capacitor fabricating process using a dual damascene process.
Embodiments relate to a capacitor and a method of fabricating a capacitor that may be capable of simplifying a manufacturing process and increasing a capacitance of a capacitor by coupling capacitors in a row.
In embodiments, a semiconductor device having capacitors may include a substrate having a capacitor region and a contact plug region, a first conductor formed on the substrate, at least one first insulating layer formed on an entire surface of the substrate including the first conductor, a first contact hole extending by passing through the first insulating layer to expose a first conductive part of the capacitor region, a second contact hole extending by passing through the first insulating layer to expose a first conductive part of the contact plug region, a second conductor formed in the first contact hole and the second contact hole, a first capacitor insulating layer formed on the second conductor aligned in the first contact hole, a third conductor formed in the first contact hole, such that the third conductor is placed on the capacitor insulating layer, and having a trench on a top thereof, a second capacitor insulating layer formed in the trench, a fourth conductor formed in the trench, such that the fourth conductor is placed on the second capacitor insulating layer, and having a trench on a top thereof, a contact plug formed on the second conductor aligned in the second contact hole, at least one second insulating layer formed on an entire surface of the substrate including the contact plug and the fourth conductor, a third contact hole extending by passing through the second insulating layer to expose the third conductor, a fourth contact hole extending by passing through the second insulating layer to expose the fourth conductor and the contact plug, a first interconnection layer formed in the third contact hole, and a second interconnection layer formed in the fourth contact hole.
First to third contact holes may be formed as via holes or trenches. The fourth contact hole may include a first via hole that may expose the fourth conductor, a second via hole for exposing the contact plug, and a trench formed on tops of the first and second via holes to overlap the first and second via holes.
The semiconductor device may also include a third insulating layer having a fifth contact hole where the first conductor is formed.
In embodiments, a method of fabricating a semiconductor device having capacitors may include preparing a substrate having a capacitor region and a contact plug region, forming a first insulating layer having a first contact hole on an entire surface of the surface, forming a first conductor in the first contact hole, forming at least one second insulating layer on an entire surface of the substrate including the first insulating layer and the first conductor, forming a second contact hole extending by passing through the second insulating layer to expose a first conductive part of the capacitor region, and a third contact hole extending by passing through the second insulating layer to expose a first conductive part of the contact plug region, forming a second conductor in each of the second contact hole and the third contact hole, forming a first capacitor insulating layer in the second contact hole such that the first capacitor insulating layer is placed on the second conductor, forming a third conductor in the second contact hole such that the third conductor is placed on the first capacitor insulating layer, and forming a contact plug in the third contact hole such that the contact plug is placed on the second conductor, forming the third conductor in the second contact hole such that the third conductor is placed on the first capacitor insulating layer, forming a trench by removing a portion of the third conductor, forming a second capacitor insulating layer in the trench, forming a fourth conductor in the trench such that the fourth conductor is placed on the second capacitor insulating layer, forming at least one third insulating layer on an entire surface of the substrate including the contact plug and the fourth conductor, forming a fourth contact hole extending by passing through the third insulating layer to expose the third conductor, and forming a fifth contact hole extending by passing through the third insulating layer to expose the fourth conductor and the contact plug, and forming a first interconnection layer in the third contact hole, and forming a second interconnection layer in the fourth contact hole.
The second to fourth contact holes may be formed as via holes or trenches. The fifth contact hole may include a first via hole for exposing the fourth conductor, a second via hole for exposing the contact plug, and a trench formed on tops of the first and second via holes to overlap the first and second via holes.
BRIEF DESCRIPTION OF DRAWINGS
FIGS. 1A to 2E are example cross-sectional diagrams illustrating a related art semiconductor and method for fabricating a MIM capacitor of a dual damascene structure; and
FIGS. 3A to 3P are example diagrams illustrating a semiconductor and method of fabricating a semiconductor having capacitors according to embodiments.
DETAILED DESCRIPTION OF EMBODIMENTS
Referring to FIG. 3A , substrate 300 may have a contact plug region and a capacitor region. First insulating layer 401 may be formed on a surface of substrate 300 .
First insulating layer 401 may be patterned, for example, through a photo and etching process such that trench 701 may be formed in first insulating layer 401 .
Referring to FIG. 3B , first conductor 501 may be formed on a surface of substrate 300 including trench 701 . First conductor 501 may be planarized, for example, through a Chemical Mechanical Polishing (CMP) process. Accordingly, first conductor 501 may be buried in trench 701 formed in first insulating layer 401 .
Referring to FIG. 3C , second insulating layer 402 , third insulating layer 403 , and fourth insulating layer 404 may be sequentially laminated on a surface of substrate 300 including first conductor 501 and first insulating layer 401 .
Referring to FIG. 3D , fourth insulating layer 404 and third insulating layer 403 may be patterned, for example, through a photo and etching process, such that first via hole 801 may be formed in the capacitor region and second via hole 802 may be formed in the contact plug region.
Referring to FIGS. 3E and 3F , fifth insulating layer 405 may be formed on a surface of substrate 300 where first and second via holes 801 and 802 may be formed. Fifth and second insulating layers 405 and 402 may be patterned, for example, through a photo and etching process, such that first trench 901 may be formed in the capacitor region and second trench 902 may be formed in the contact plug region.
First via hole 801 may pass through second insulating layer 402 , which may be placed in the capacitor region, and may expose a portion of conductor 501 .
Second via hole 802 may pass through second insulating layer 402 , which may be placed in the contact plug region, and may expose a portion of conductor 501 .
First trench 901 may be coupled to first via hole 801 of the capacitor region. Accordingly, a width of first trench 901 may be identical to that of first via hole 801 . A depth of first via hole 801 may be as deep as first trench 901 , according to embodiments.
In other words, a contact hole of a single damascene structure that may expose a portion of first conductor 501 may be formed in the capacitor region.
Second trench 902 may be coupled with second via hole 802 of the contact plug region. A width of second trench 902 may be wider than that of second via hole 802 . That is, a contact hole of a dual damascene structure that exposes a portion of first conductor 501 may be formed in the contact plug region.
Referring to FIG. 3G , second conductor 502 may be laminated on a surface, for example where first and second trenches 901 and 902 and first and second via holes 801 and 802 may be formed. First capacitor insulating layer 601 may be laminated and/or formed on second conductor 502 within the first trench 901 .
Referring to FIG. 3H , first capacitor insulating layer 601 may be patterned, for example, through a photo and etching process, such that first capacitor insulating layer 601 may be formed only along inner walls of first trench 901 and first via hole 801 .
That is, first capacitor insulating layer 601 may be formed only in the capacitor region and not formed in the contact plug region.
Referring to FIG. 3I , metallic layer 555 may be formed on a surface of substrate 300 , including first capacitor insulating layer 601 and second conductor 502 .
Referring to FIG. 3J , metallic layer 555 , second conductor 502 , and first capacitor insulating layer 601 may be polished through a CMP process, until a surface of fifth insulating layer 405 appears.
Third conductor 503 , which may be buried in first via hole 801 and first trench 901 , may thus be formed in the capacitor region. Contact plug 777 , which may be buried in second via hole 802 and second trench 902 , may thus be formed in the contact plug region.
Referring to FIG. 3K , a portion of third conductor 503 may be removed and trench 702 may thus be formed.
Referring to FIG. 3L , second capacitor insulating layer 602 and metallic layer 556 may be sequentially deposited on a surface of substrate 300 including trench 702 and second capacitor insulating layer 602 .
Referring to FIG. 3M , metallic layer 556 and second capacitor insulating layer 602 may be polished through a CMP process, until a surface of fifth insulating layer 405 appears. Second capacitor insulating layer 602 and fourth conductor 504 , which may be buried in trench 702 , may be formed in the capacitor region.
Referring to FIG. 3N , sixth insulating layer 406 may be formed on a surface of substrate 300 including second capacitor insulating layer 602 and fourth conductor 504 . Sixth insulating layer 406 may be patterned, for example, through a photo and etching process such that third via hole 803 and third trench 903 , that may expose a portion of third conductor 503 may be formed. Fourth via hole 804 and fourth trench 904 , which may expose a portion of fourth conductor 504 , and fifth via hole 805 , which may expose a portion of contact plug 777 , may be formed. Fourth trench 904 may be commonly coupled to fourth via hole 804 and fifth via hole 805 . That is, fourth trench 904 may be formed on tops of fourth and fifth via holes 804 and 805 , and may overlap both of fourth and fifth via holes 804 and 805 .
Referring to FIG. 3O , metallic layer 999 may be formed on a surface of substrate 300 including third via hole 803 , fourth via hole 804 , fifth via hole 805 , third trench 903 and fourth trench 904 .
Referring to FIG. 3P , metallic layer 999 may be polished, for example through a CMP process, until a surface of sixth insulating layer 406 appears.
First and second interconnection layers 991 and 992 may be formed through the above described processes.
First interconnection layer 991 may be electrically coupled with third conductor 503 , and second interconnection layer 992 may be electrically coupled with fourth conductor 504 and contact plug 777 .
Accordingly, two capacitors connected in parallel to each other may be formed in the capacitor region.
That is, a first capacitor including second conductor 502 , third conductor 503 and first capacitor insulating layer 601 , and a second capacitor including third conductor 503 , fourth conductor 504 and second capacitor insulating layer 602 may be provided.
Second conductor 502 of the first capacitor may be electrically coupled to fourth conductor 504 of the second capacitor through first conductor 501 , second conductor 502 (second conductor 502 of the contact plug region), contact plug 777 , and the second interconnection layer 992 . Therefore, the first capacitor and the second capacitor may be connected in parallel to each other.
According to embodiments, each of the dielectric layers (first to sixth insulating layers 401 to 406 ), and first and second capacitor insulating layers 601 and 602 may be formed by using a nitride layer, a SiC aluminum oxide, or a silicon oxide.
First, second, third, and fourth conductors 501 , 502 , 503 , and 504 may be formed of a TaN or a multilayer having a TaN, a TiN or a multilayer having a TiN, and a WN or a multilayer including a WN. Further, the capacitor dielectric layer may act as a capacitor interlayer insulating layer, and may be formed of any one of a Nitride layer, a TEOS, a Tantalum based oxide, and an Aluminum based oxide.
According to embodiments, a semiconductor device may have capacitors, which may be connected in a row. Capacitance of the capacitor may thus be improved.
That is, the capacitors provided in the semiconductor device according to embodiments may have mass storage capacitance, for example as compared to a related art capacitor.
Further, according to embodiments contact plug 777 and the capacitors may be fabricated through the same process. Accordingly, a fabrication process may be simplified.
It will be apparent to those skilled in the art that various modifications and variations can be made to embodiments. Thus, it is intended that embodiments cover modifications and variations thereof within the scope of the appended claims. It is also understood that when a layer is referred to as being “on” or “over” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present.
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Embodiments relate to a semiconductor having a capacitor and a method of fabricating the same, that may be capable of simplifying a manufacturing process and increasing a capacitance of a capacitor. In embodiments, a method of forming a capacitor may use a dual damascene process and may be simplified by simultaneously forming a contact plug for applying a bias voltage to a bottom electrode and a capacitor.
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RELATED APPLICATION DATA
[0001] This application claims the benefit of U.S. Provisional Patent Application No. 61/249,727 filed Oct. 8, 2009, the disclosure of which is herein incorporated by reference in its entirety.
FIELD OF THE INVENTION
[0002] This invention relates to a process for increasing the percentage of recovered ferrous or non-ferrous metal concentrates such as aluminum concentrate from certain types of dross.
SUMMARY OF THE INVENTION
[0003] The process of the present invention produces a high percentage of recovered concentrates of aluminum (or other metals) from certain types of dross that can be directly melted in a sidewell or similar type furnace without the use of salt flux.
[0004] These high metal content concentrates are obtained in accordance with the present invention by mechanically processing the dross to mechanically separate and remove the oxide and salt components from the metal component while keeping the metal component in its largest particle size possible.
[0005] Dross, as used herein, may include solid scum that forms on the surface of a metal when molten or during melting, and is largely the result of oxidation, but may also include a mixture of salt and flux. A common metal that is recoverable using this process is aluminum or aluminum alloys (collectively referred to herein as aluminum). However, such a process can also be used to reclaim other metals from dross containing the metals including magnesium, copper, brass, zinc and certain steel types.
[0006] In the case of aluminum, the dross types that particularly lend themselves to this process are primary pressed and non-pressed white dross (i.e., dross that primarily contains aluminum and oxides) pressed and non-pressed black dross (i.e., dross that contains aluminum, oxides and a combination of fluxes), extrusion alloy pressed dross and salt cake.
[0007] In accordance with one aspect of the invention, the oxides and salt components and other smaller particles in the dross that are mechanically adhered to the metal component are crushed or crumbled and shaken off from the larger metal particles and screened off to separate the larger metal particle concentrate from the smaller particles.
[0008] In accordance with another aspect of the invention, the larger metal particle concentrate is directly fed into a sidewell or similar type furnace for direct melting of the larger metal particle concentrate.
[0009] In accordance with another aspect of the invention, the smaller metal particles to which some oxide and salt components may still be adhered are separated from the finer oxides and flux content previously removed for further mechanical processing of the smaller metal particles to remove any remaining oxide and salt components from the smaller metal particles.
[0010] In accordance with another aspect of the invention, the smaller metal particle concentrate from which any remaining oxide and salt components have been removed are submersed into the melted larger metal particle concentrate in the sidewell furnace using a suitable submergence system such as a vortex pump or puddling to melt the smaller metal particle concentrate.
[0011] In accordance with another aspect of the invention, the remaining fines of oxide and salt components may be further processed for any remaining metal content or other by-product or placed in landfill depending on the economics.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a block flow diagram showing the process for recovering a high percentage content of metal concentrates from dross in accordance with the present invention.
[0013] FIG. 2 is a schematic fragmentary perspective sectional view through one form of rotary lump crusher/reclaimer apparatus that may be used to mechanically separate and remove the oxide and flux salt components from the larger metal particles during the first phase of the dross recycling process of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0014] Referring now in detail to the drawings, FIG. 1 is a block flow diagram of the process for recovering a high percentage content of metal concentrates from dross in accordance with the present invention. The process utilizes a rotary lump crusher/reclaimer apparatus 1 which may be of the type shown in greater detail in FIG. 2 made by Didion Manufacturing Company of St. Peters, Mo., to mechanically separate and remove the oxide and flux salt components from the metal component while keeping the metal component in the largest particle size possible. This is because the metal, for example aluminum, is a malleable metal that can be formed into various shapes without breaking, whereas the oxides and flux salts are friable and can be crumbled or crushed to powder.
[0015] The rotary crusher/reclaimer apparatus 1 shown in FIG. 2 includes an outer cylinder 2 having an intake compartment 3 at the front end in which the dross material to be processed is fed as by means of a conveyor, shovel, load hopper, vibratory conveyor or any other suitable means that places a large amount of the dross material into the entry end of the apparatus. Intake compartment 3 contains suitable means to separate large clumps of the dross material into smaller clumps of material and convey the material into an adjacent section 4 containing crushing and grinding means 5 . If any metal particles contained in the dross are too large to pass through the crusher section 4 , the flow through the apparatus may be periodically reversed for a sufficient period of time to back the excessively large metal particles out of the apparatus. If upon inspection these very large metal particles are free of oxide and flux salt components, they may be fed directly into a sidewell type furnace 6 , schematically shown in FIG. 1 , for melting without the use of salt flux.
[0016] During passage of the remaining dross material through the crusher section 6 , virtually all of the oxide and flux components are crumbled or crushed into powder and shaken off the remaining larger metal particle concentrate, but not completely off the smaller metal particles because the smaller metal particles must be impacted to a much greater degree than the larger metal particles to separate the oxide and flux components from the smaller metal particles.
[0017] Following the crusher section 4 , the material enters an attrition chamber 7 where the oxide and flux components and other smaller particles that have been crushed and shaken off the larger metal particle concentrate during the tumbling and crushing process and the smaller metal particles that still have some of the oxide and flux components adhered thereto are screened off from the larger metal particle concentrate through deck holes 8 in an inner cylinder wall 9 for further processing as described hereafter.
[0018] The attrition chamber 7 may contain blades 10 to further assist in removal of the oxide and flux components from the metal particle concentrates. This larger metal particle concentrate 15 (which is free of the oxide and flux components) is removed from the back end 16 of the crusher/reclaimer apparatus 1 and may be fed directly into the sidewell type furnace 6 as schematically shown in FIG. 1 for direct melting of the larger metal particle concentrate without the use of salt flux.
[0019] The smaller particulate material that passes through the deck holes 8 into the space between the inner and outer cylinders 9 and 2 is swept forwardly toward the intake area 3 of the apparatus 1 by continuing conveyor means in the form of helical vanes 17 between the inner and outer cylinders for classification through a multiple screening system 18 having a smaller screening section 19 that separates out the oxide and flux fines from the smaller metal components. A more detailed description of the construction and operation of a rotary lump crusher/reclaimer apparatus of the type shown in FIG. 2 can be found in U.S. Pat. No. 5,974,865, assigned to Didion Manufacturing Company, the entire disclosure of which is incorporated herein by reference.
[0020] The size of the deck holes 8 in the inner cylinder portion 9 of the attrition chamber 7 may vary depending on the size of the smaller metal particles in the dross being reclaimed and the minimum size of metal particle concentrate in the dross that are freed of all of the oxide and flux components (and other foreign particles) adhered thereto during passage through the lump crusher/reclaimer apparatus.
[0021] If the dross is aluminum dross of the type described herein, the apparatus will effectively remove all of the oxide and flux components from aluminum particles in the dross having a diameter of 15 millimeters (mm) or greater. Accordingly, the deck holes may be 15 mm or larger in diameter. However, the larger the deck holes, the less percent of metal particle concentrate in the dross that would be removed from the back end of the apparatus for direct feeding into a sidewell type furnace and the greater the percent of material containing additional metal particle concentrate requiring further processing to remove the oxide and flux components therefrom as described hereafter. Accordingly, when processing aluminum dross of the type described herein, it would be preferable to make the deck holes no smaller than 15 mm and no larger than 25 mm in diameter.
[0022] The purpose of the multiple screening system 18 adjacent the front end of the apparatus is to separate out the free oxide and flux fines from the remaining smaller metal components prior to further processing of the smaller metal components to recover as much of the free metal concentrate contained therein as possible. If the dross is aluminum dross of the type described herein, most of the smaller aluminum particles contained in the dross would have a diameter of 2 mm or larger. Since the fine oxides and fluxes already removed from the aluminum particles would have a diameter less than 2 mm, the smaller particles or fines 20 having a diameter of less than 2 mm are desirably separated out from the larger particles by the smaller screening section 19 and removed from the apparatus for further processing for any remaining metal content or other by-product or placed in landfill as schematically shown in FIG. 1 depending on the economics.
[0023] The remaining smaller metal particles 25 are also removed from the apparatus 1 through another section 26 and transferred to a high velocity impactor 27 , schematically shown in FIG. 1 , for high speed impacting to remove all of the remaining oxide and salt components or other particles from the smaller metal particles. Then all of the material is transferred from the impactor 27 to a multiple screening system 28 , also schematically shown in FIG. 1 , to separate out the smaller metal particle concentrate 29 (which if aluminum has a minimum particle diameter greater than 2 mm) from the much smaller fines 30 (which have a maximum particle diameter less than 2 mm). These fines 30 , along with the fines 20 removed from the rotary lump crusher/reclaimer apparatus 1 , can be further processed for any remaining metal content or other by-products or placed in landfill depending on the economics. The smaller metal particle concentrate 29 obtained by this further process may then be mechanically submerged underneath the already melted large metal concentrate in the sidewell furnace 6 using a suitable submergence system such as a vortex pump or puddling to melt the additional smaller metal concentrate.
[0024] From the foregoing, it can be seen that this process can be utilized to produce concentrates of aluminum (or other metals) from dross that are in excess of 95% in recovered metal content. These concentrates can be directly melted in a reverb or sidewell type furnace without the use of salt flux, and without generating any salt cake.
[0025] Although the invention has been shown and described with respect to certain embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of the specification. In particular, with regard to the various functions performed by the above-described components, the terms (including any reference to a “means”) used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed component which performs the function in the herein illustrated exemplary embodiments of the invention. Also, all of the disclosed functions may be computerized and automated as desired. In addition, while a particular feature of the invention may have been disclosed with respect to only one embodiment, such feature may be combined with one or more other features as may be desired and advantageous for any given or particular application.
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A process for increasing the percentage of metal recovery from dross containing metal particles of different sizes having oxide and salt components adhered thereto. The process includes crushing and tumbling the dross to mechanically remove all of the oxide and salt components from the larger of the metal particles, separating the larger metal particles from the removed oxide and salt components and the smaller metal particles to provide a supply of larger metal particle concentrate, separating the removed oxide and salt components from the smaller metal particles, mechanically impacting the smaller metal particles to remove any additional oxide and salt components from the smaller metal particles, and separating the smaller metal particles from the additional oxide and salt components to provide a supply of smaller metal particle concentrate.
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CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the benefit U.S. Provisional Patent Application No. 60/796,786, filed May 1, 2006.
SUMMARY
In accordance with certain aspects, a vehicle supporting platform can be supported at plural locations (e.g., four locations) from below such that the platform can pivot fore to aft and side to side in response to the impact of wind on a vehicle on the platform. In a desirable form, the platform is suspended by four suspension rods or cables that loosely support the respective corners of a platform supporting structure. The platform supporting structure can be positioned in a bay beneath the floor level. Although a different number of sensors can be used, in one approach there is one aft motion sensor coupled to the front of the floor supporting frame and a wall portion of the bay and two side sensors, one adjacent to the front of the platform and the other adjacent to the rear of the platform. Both of the side sensors can be on the same side of the platform. A double ball joint can be used to couple the sensor to the structure in one embodiment to eliminate off axis loading. A structure such as a locking collar arrangement can be used in an embodiment to facilitate disconnecting the sensor from the platform.
TECHNICAL FIELD
The technology disclosed herein relates to wind tunnel balances for use in measuring aerodynamic forces and for supporting a vehicle, such as a truck, during wind tunnel testing.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of exemplary support structure for one embodiment of a vehicle wind tunnel balance.
FIG. 2 is an end view of the embodiment of FIG. 1 .
FIG. 3 is a top view of a wind tunnel balance with a vehicle shown schematically on a support surface of the wind tunnel balance.
FIG. 4 is a closeup view of one of a plurality of supports utilized to suspend the wind tunnel balance from a wall of an underground bay within which the wind tunnel balance support structure is positioned.
FIG. 5 is a schematic view illustrating an exemplary positioning of a truck on the upper surface of the wind tunnel balance and illustrating an exemplary positioning of load cells used to measure forces arising from wind directed toward the truck when positioned on the balance in a wind tunnel.
FIG. 6 schematically illustrates forces on a truck subjected to wind when on the wind tunnel balance.
FIGS. 7 and 8 illustrate exemplary mounting assemblies.
FIGS. 9 and 10 illustrate an example of a coupling that can be used with one form of a load cell mounting structure to permit decoupling of the load cell from the wind tunnel balance supporting framework.
DETAILED DESCRIPTION
With reference to FIGS. 1 through 4 , an exemplary form of wind tunnel balance for vehicles in accordance with this disclosure is shown. In this example, a supporting frame structure, such as a frame 10 , carries a vehicle supporting surface 12 which is desirably has a planar upper surface and can be formed of, for example, sheets of ⅝ inch aluminum decking secured to a frame. An exemplary balance deck 12 is sized to support heavy duty trucks with an exemplary dimension being 12′×30′. FIG. 3 illustrates a schematic version of a truck 14 having front wheels 16 , 18 and sets of rear wheels 20 , 22 , 24 and 26 coupled to respective tandem axles 28 , 30 . Desirably, deck 12 is substantially flush with or in the plane of a floor portion of the wind tunnel 34 that is spaced from the deck by a perimeter gap 36 . The wind tunnel is provided with a frame receiving under floor level bay within which the frame 10 is positioned. The illustrated bay comprises first and second spaced apart parallel upright side walls 50 , 52 , front and rear walls 54 , 56 , and a floor 60 . The walls 50 , 52 are supported by respective footings 62 , 64 .
The frame 10 supports the deck 12 so as to float (move fore and aft, side-to-side and twist) relative to the floor and within the gap 36 in response to forces applied by wind impacting a vehicle positioned on the deck. In accordance with this disclosure, a four point pendulum support approach is used. With reference to FIG. 3 , and as will be more apparent from the discussion below, the frame 10 is suspended at four locations 70 , 72 , 74 and 76 . Desirably, elongated supports coupled to walls of the bay are used to hang the frame at the respective locations 70 , 72 , 74 and 76 . As a specific approach, four elongated rods are utilized to suspend the frame, each rod having an upper end coupled by a bracket mounted to one of the walls and a lower end coupled to the frame.
The illustrated frame 10 comprises first and second parallel spaced apart longitudinally extending supports, such as I-beams 100 , 102 . In addition, spaced apart lateral or transversely extending deck supports, such as beams 108 , are carried by the respective I-beams 100 , 102 with the deck 12 being positioned on top of the supports 108 . The supports 108 desirably comprise I-beams at two foot intervals along the length of the longitudinally extending beams 100 , 102 . The outermost ends of the supports 108 , as indicated for one such end 110 , are notched at their underside to provide a clearance gap above the upper end of the associated side wall (e.g., wall 50 ). As can be seen in FIG. 2 , the ends of support 108 overlap the respective upper ends of the walls 50 , 52 . In the event the frame 10 were to fail, or become overloaded, the walls 50 , 52 would prevent the deck 12 from falling into the bay.
A first suspension structure is provided to support the front end portions of beams 100 , 102 and a similar second rear suspension structure is used to support the rear end portions of the beams 100 , 102 . The suspension structures can be identical and for this reason only the front suspension structure will be described.
More specifically, with reference to FIGS. 1 , 2 and 4 , the illustrated front suspension structure comprises first and second upright, in this case vertical, supports 130 , 132 . Supports 130 , 132 can, for example, be box beams of tempered steel that are 4″×4″ wide by ⅜″ thick, although these dimensions and material can be varied. A cross member 136 , which can be of the same material as uprights 130 , 132 , extends across the lower portion of the suspension structure with outer end portions 138 , 140 of cross member 136 extending transversely beyond the lower ends of the respective uprights. Respective connectors, such as base plates 142 , 144 , are positioned underneath the respective end portions of cross member 136 and the lower end portions of the respective supports 130 , 132 . Respective upright connectors, such as gusset plates 146 , 148 , extend upwardly from the respective plates 142 , 144 . In this example, the gusset 146 is positioned against the front surface of upright 130 and the rear surface of cross member 136 and the gusset 148 is positioned against the upper surface of upright 132 and the rear surface of cross member 136 . These components can be secured together, such as by welding, to provide a rigid interconnected structure. Upwardly angled front and rear braces or reinforcements 180 , 182 can be secured at the lower ends to the structure including gusset plate 142 and at their upper ends to the undersurface of beam 100 . Gussets can also be used to assist in securing the upper ends of the braces 180 , 182 to the I-beam 100 . One such gusset is shown at the upper end of support 182 in FIG. 1 . Similar braces can also be positioned for connection from the structure including gusset 144 to I-beam 102 . Supports 180 , 182 can, for example, be angle beams.
Respective cross supports are also included in the front suspension structure of this example. These cross supports can comprise respective cross members 200 , 202 , such as angle beams. Cross members 200 , 202 are desirably secured together at their intersection, such as by welding to a connection plate or gusset 204 . The lower end portion of cross member 200 is secured, as by welding, to gusset 146 and the upper end portion of cross member 200 is secured, as by welding, to a reinforcing gusset 210 mounted to I-beam 200 . In the same manner, the lower end portion of cross member 202 is secured, as by welding, to gusset 148 and the upper end portion of cross member 202 is secured, as by welding, to a gusset 212 mounted to I-beam 100 . It should be noted, however, that other connection approaches and support structures can be used. The illustrated structure does provide a desirable rigid framework for supporting the deck 12 .
As previously mentioned, the frame 10 and thus the deck 12 is supported so as to float within the bay during normal operation of the wind tunnel balance. This floating support is accomplished by four elongated supports, such as cables or rods suspending the structure from components forming the bay. In the specifically illustrated approach, both the front and rear suspension structures are supported in the same manner. Therefore, only the front support approach of this example will be described. With reference to FIGS. 2 and 4 , respective wall mounted brackets 220 , 222 are bolted or otherwise mounted to the side walls 50 , 52 of the bay. These brackets each comprise a respective upright horizontally extending support flange 224 , 226 and a respective wall mounting flange 228 , 230 . Wall mounting flange 228 abuts the surface of wall 50 whereas wall mounting flange 230 abuts the surface of wall 52 in this example. Each of the brackets 220 , 222 also comprises a respective upright reinforcing flange 232 , 234 . A first rod 260 , which may be threaded along its length, has its upper end portion inserted through an opening in flange 224 with one or more nuts being secured to the rod at its upper end to prevent the rod from passing downwardly through the bracket. The lower end of rod 260 extends through an opening in gusset 142 and is secured from below by one or more nuts. A similar rod 262 is secured in the same manner to bracket flange 226 and the gusset 144 . With four such support rods being provided, two at the front and two at the rear for suspending the respective front and rear support structures and thereby the deck, the deck is floatingly supported at the four locations 70 , 72 , 74 and 76 (see FIG. 3 ) to allow movement of the deck within limits in response to wind impacting a truck positioned on the deck in the wind tunnel.
Respective locking pins (shown schematically at 297 in FIG. 5 ) may be inserted through openings in the deck and into brackets (shown schematically at 299 in FIG. 5 ) coupled to the walls to prevent the deck from shifting at selected times, such as when the wind tunnel balance is not in use.
Desirably, the gap 36 is uniform and a uniform clearance is provided from the platform to the pit (such as ¼″ clearance). Exemplary support rods 260 , 262 are ⅝″ threaded support rods.
A plurality of load cells couple the framework to the adjacent walls of the bay. Although any number of load cells can be used, desirably three such load cells are employed. With reference to FIGS. 3 and 5 , two of the load cells 280 , 282 are positioned between wall 50 and the frame at respective fore and aft locations along the wall. In addition, a load cell 284 is positioned at the front of the structure extending between wall 54 and the frame and positioned along the longitudinal center of the wind tunnel balance. These load cells can be of any suitable type with a specific example being strain gauge containing load cells that provide an electrical signal indicative of the force detected by the load cell. A specific exemplary load cell is a Honeywell Model No. 41 Sensotech Precision Pancake load cell. These load cells can be used to determine drag, side forces and yawing moments in response to wind directed against a vehicle in the wind tunnel. For example, with reference to FIG. 6 , drag corresponds to forces in the direction of arrow 300 in response to wind impacting the vehicle, side forces correspond to forces in the direction of arrow 302 in response to side directed wind components, and the yawing moment corresponds to twisting forces in the direction indicated by arrow 304 . Forces measured by the load cells are used to compute drag, side forces and yawing moments in response to wind impacting the vehicle in the wind tunnel.
With reference to FIGS. 7-10 , exemplary load cell coupling structures are illustrated. In FIG. 7 , the load cell 284 is shown coupled to a mounting block 310 that is mounted to wall 54 . A rod structure 312 is coupled at one end 314 by a ball joint to the load cell and at the opposite end 316 by another bolt ball joint to a clevis support 318 . Support 318 is mounted by a support structure 320 to the undersurface of two of the cross beams 108 . In addition, with reference to FIG. 8 , the load cell 280 is mounted by a support 330 to the wall 350 . A coupling rod structure 332 is coupled at a first end portion by a ball joint 334 to the load cell 280 and at a second end portion 336 by a ball joint to a clevis structure 338 mounted to a cross piece 340 . Cross piece 340 is coupled to one of the I-beams 108 (not shown in FIG. 8 ). The use of double ball joints to connect the respective ends of the support pin structures to their associated load cells and mounting brackets eliminates off-axis loading of the load cells. This structure can be altered if desired, for example, if more load cells are used.
The pin structures 312 and 332 can be identical and may comprise a one piece pin. However, more desirably, with reference to FIGS. 9 and 10 , the pin structures (described for structure 312 ) comprises a first pin section 360 with a first end portion coupled to the load cell and a second end portion 362 inserted into a locking collar 364 . In addition, a second pin section 370 has one end portion coupled to the deck mounting framework and the opposite end portion 372 coupled to the locking collar. Although other coupling mechanisms can be used, an exemplary locking collar 364 comprises a machinable-bore, one-piece, clamp-on, coupling from McMaster-Carr. With this particular locking collar, the loosening of set screws 380 allows the end portion 372 to be removed from the locking collar to thereby separate the load cell from the deck. This can be done, for example, to facilitate changing of the load cell or to protect the load cell at times when the load cell is not being used to measure forces.
Although the wind tunnel balance described herein may be used in any suitable wind tunnel, an exemplary wind tunnel is set forth in U.S. Pat. No. 6,820,477, a copy of which is included herewith and forms a portion of this disclosure.
In this disclosure, the terms “a”, “an” and “at least one” include one and also more than one of the referenced components. Also, the term “coupled” encompasses direct connections and indirect connection through one or more other components.
Having illustrated and described the principles of our invention with reference to illustrated embodiments, it should be apparent to those of ordinary skill in the art that these embodiments can be modified in arrangement and detail without departing from the inventive principles disclosed herein. We claim all such modifications.
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A vehicle supporting platform can be supported at plural locations (e.g., four locations) from below such that the platform can pivot fore to aft and side to side in response to the impact of wind on a vehicle on the platform. In a desirable form, the platform is suspended by four suspension rods or cables that loosely support the respective corners of a platform supporting structure. The platform supporting structure can be positioned in a bay beneath the floor level. Although a different number of sensors can be used, in one approach there is one aft motion sensor coupled to the front of the floor supporting frame and a wall portion of the bay and two side sensors, one adjacent to the front of the platform and the other adjacent to the rear of the platform. Both of the side sensors can be on the same side of the platform. A double ball joint can be used to couple the sensor to the structure in one embodiment to eliminate off axis loading. A structure such as a locking collar arrangement can be used in an embodiment to facilitate disconnecting the sensor from the platform.
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CROSS REFERENCES
This application claims the benefit of U.S. Provisional Application No. 61/046,289, entitled “OPTICAL COLLECTION DEVICE UTILIZING DIFFERENTIAL AREA PHOTODIODES FOR REJECTING PARASITIC AMBIENT LIGHT AND MAXIMIZING RETROCOLLECTED MODULATED LASER LIGHT”, filed Apr. 18, 2008, and is hereby incorporated by reference.
BACKGROUND
Conventional laser bar code readers scan a laser beam across a distant bar code label and detect an optical signal reflected off the bar code. However, ambient light, from sources such as low energy lights, neon signs, and sunlight, are also present in the detected signal. The frequency range of the ambient parasitic light is wide, ranging from DC to high frequencies. The ambient light component severely degrades the signal to noise ratio of the reflected bar code signal when the reading distance between the bar code reader and the bar code increases.
Retro reflection systems are well known in the art for extracting a signal from random noise. However, these systems are large, have low scanning frequencies, and are costly. Thus, they are not suited for use in handheld computers or bar code scanners.
There is a need for a system that overcomes the above problems, as well as providing additional benefits. Overall, the above examples of some related systems and associated limitations are intended to be illustrative and not exclusive. Other limitations of existing or prior systems will become apparent to those of skill in the art upon reading the following Detailed Description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a system block diagram of a bar code reader.
FIGS. 2A and 2B show an example of collection optics imaging a field of view.
FIG. 3 shows an example of two adjacent collection optics with photodiodes mounted on flexible circuits.
FIG. 4 shows a ray tracing diagram of laser light collected by two adjacent reflective optics.
FIG. 5 shows an example of the active areas of the photodiodes used with the present invention.
FIG. 6 is a circuit diagram showing an example of an electronic circuit used to remove the parasitic ambient light from a detected laser bar code signal.
FIG. 7 shows an example of an alternative sensor configuration.
FIG. 8 depicts a flow diagram illustrating a suitable process for reading an indicia and rejecting ambient light.
DETAILED DESCRIPTION
Described in detail below is a bar code reader that uses an optical collection system to image light onto differential area photodiodes. In a suitable example, three photodiodes may be used, including a first main photodiode that receives the laser bar code signal along with ambient light and two smaller photodiodes located on either side of the main photodiode that receive only the ambient light. In one example, the total of the active areas of the two smaller photodiodes is approximately equal to the active area of the main photodiode.
Various aspects of the invention will now be described. The following description provides specific details for a thorough understanding and enabling description of these examples. One skilled in the art will understand, however, that the invention may be practiced without many of these details. Additionally, some well-known structures or functions may not be shown or described in detail, so as to avoid unnecessarily obscuring the relevant description.
The terminology used in the description presented below is intended to be interpreted in its broadest reasonable manner, even though it is being used in conjunction with a detailed description of certain specific examples of the invention. Certain terms may even be emphasized below; however, any terminology intended to be interpreted in any restricted manner will be overtly and specifically defined as such in this Detailed Description section.
A bar code reader includes optics for focusing a laser beam and scanning it across a bar code and optics for collecting the laser light reflected off the bar code. The collection optics are designed to optimize the field of view, maximize the collection area, and collect the light on a photodetector. However, parasitic ambient light is present on and around the area near a bar code. The ambient light may have both a DC and a modulated frequency component. When modulated ambient light is superimposed upon the laser light reflected off a bar code, the signal to noise ratio at the photodetector of the bar code signal is degraded, especially when the reading distance between the bar code and the bar code reader increases. To improve the bar code signal, the bar code reader may capture the ambient light near the bar code and subtract it from the light reflected from the bar code that includes ambient light.
Conventional laser bar code readers, either retro reflective or fixed collective, detect reflected light at a point location. Alternatively, a mirror sends reflected light to a point detector, or a collective optic focuses reflected light onto a point detector. In both of these cases, it is impossible to remove ambient light with an additional detector because there is no image of the indicia, and illumination light rays reflected from the indicia would be collected in both light detecting photodiodes.
FIG. 1 shows an example block diagram 100 of a bar code reader used to read bar codes or other indicia at a distance. A bar code reader may include one or more light sources 110 , a scanning mirror 115 , imaging optics 120 , and bar code reader electronics 190 .
The light sources 110 include light source means such as laser diodes, solid state lasers, light emitting diodes (LEDs), incandescent bulbs, halogen lamps, and gas discharge lamps. A focused light source 110 such as a laser may be used for illuminating a bar code. Alternatively, a non-laser light source 110 may be used to illuminate a bar code in the present invention, provided the light source is sufficiently focused. A scanning mirror 115 may be used to scan the laser 110 across a bar code or other indicia 118 , and imaging optics 120 may be used to collect the laser light reflected from a first area surrounding and including the bar code 118 onto a primary light detector 130 . Alternatively, the scanning mirror 115 may be shaped to provide the functionality of the imaging optics 120 . The imaging optics 120 also image light from one or more areas near, but should not be overlapping, the first area onto one or more secondary light detectors 130 . The secondary light detectors 130 do not receive any light reflected from the bar code 118 .
The bar code reader electronics 190 may include one or more light detectors 130 , processors 140 , memory units 180 , communications modules 150 , input/output devices 160 , and power supplies 170 .
The light detectors 130 include light sensing means such as photodiodes, PIN diodes, photodetectors, photoconductors, charge-coupled devices (CCD) that can convert an optical signal into an electrical signal. A processor 140 may be used to decode the electrical signals from the detectors 130 . Memory units 180 may include, but are not limited to, RAM, ROM, and any combination of volatile and non-volatile memory. The memory units 180 may store the converted electrical Communications modules 150 may be used to transmit scanned bar codes either wirelessly or through electrical or optical cables to another device, a database, a memory unit, and/or a processor. Input/output devices 160 may include, but are not limited to, triggers to start and stop the bar code reader or to initiate other bar code reader functions, visual displays, speakers, and communication devices that operate through wired or wireless communications. Power supplies 170 may include, but are not limited to, a battery or an electrical wall outlet.
FIG. 2A shows an example imaging diagram 200 generated by collection optics 210 used by a laser bar code reader. The collection optics 210 may include, but are not limited to, a lens or a mirror, and a plurality of photodetectors. The collection optics 210 see a field of view 220 . Three particular areas are delineated in the field of view 220 , a top rectangular area 222 , a middle rectangular area 224 , and a bottom rectangular area 228 . Within the middle rectangular area 224 lies a bar code (not shown) to be scanned. A laser in the bar code reader scans a line 226 in the field of view 220 in order to read the bar code. The sum of the areas of the top and bottom rectangular areas 222 , 228 are approximately equal to the area of the middle rectangular area 224 in one example. Because parasitic ambient light is present throughout the field of view 220 , and the intensity of the ambient light is essentially spatially independent, the total ambient light to which the top and bottom rectangular areas 222 , 228 are exposed is approximately equal to the ambient light to which the middle rectangular area 224 is exposed.
The collection optics 210 image the field of view 220 onto an image plane 230 . The top rectangular area 222 in the field of view 220 is imaged to area 232 , the bottom rectangular area 228 in the field of view 220 is imaged to area 238 , and the middle rectangular area 224 in the field of view 220 is imaged to area 234 in this example. Three separate photodiodes may be used in the image plane 230 with active areas covering each of the areas 232 , 234 , 238 .
Alternatively, a non-laser light source may be used to illuminate the bar code as long as the light source is focused to illuminate only the rectangular area 224 around the bar code and not the neighboring areas 222 , 228 . If the bar code is not entirely contained within the rectangular area 224 , the light source must still be focused to stay within the rectangular area 224 . In another example, a scanning mechanism may use optics to spread light from a light source, such as a laser, into a narrow line of light and project the line of light onto the bar code, while remaining entirely within the area 224 . It is important that the light be confined within the area 224 because the light source must not illuminate the photodiodes 232 , 238 that sense ambient light from, respectively, the top and bottom rectangular areas 222 , 228 in the field of view 220 .
FIG. 2B shows an expanded diagram 250 of the image plane 230 . Because the parasitic ambient light is evenly distributed over the field of view 220 , upon imaging by the collection optics 210 , the parasitic ambient light 260 is also evenly distributed in the imaging plane 230 . The line 226 scanned by the laser in the field of view 220 is imaged as line 236 . Also shown in the image plane 230 is the image of the bar code 237 scanned by the laser. Note that the bar code image 237 and the image of the laser scan line 236 are both contained in the area 234 and do not overlap the adjacent areas 238 , 232 . It will be apparent to a person skilled in the art that the collection optics 210 may magnify or shrink the field of view 220 as it is imaged onto the image plane 230 , but the ratio of the dimensions of the areas 222 , 224 , 228 is substantially maintained in the image plane 230 . Each of the three photodiodes 238 , 234 , 232 in the image plane 230 converts the light impinging upon its surface into an electrical current. Thus, due to the fidelity of the image plane, all three photodiodes receive and convert parasitic ambient light, but only the photodiode covering area 234 receives and converts the laser signal reflected off the bar code.
FIG. 3 shows a front isometric view of a suitable example 300 of two juxtaposed optical collection imagers 310 , 320 . The optical imagers 310 , 320 each have a concave mirror designed to maximize the collecting area, optimize the optical field, and focus light onto an image plane. A rectangular hole 330 between the two optical collection mirrors 310 , 320 permits a laser beam to pass through. The arrows near the top of example 300 indicate that the bar code or indicia to be scanned is located towards the right side of the imagers 310 , 320 , and the light reflected from the bar code travels in the opposite direction. The laser from the bar code reader is scanned across a bar code, and the reflected light is focused and imaged by the mirrors 310 , 320 onto photodiodes or other transducers that convert light to electricity located on the underside of flexible circuits 315 , 325 , as indicated by the dotted lines. It will be apparent to a person skilled in the art that although two optical collection imagers are used in example 300 , any number of collection imagers may be used to image the laser light reflected off a bar code, such as one imager or three or more imagers.
FIG. 4 shows an example ray tracing diagram 400 of the example 300 having two juxtaposed optical collection imagers 310 , 320 . For clarity, the rays internal to the bundle of rays depicted in diagram 400 are not shown. A laser beam 410 is seen entering from the left side of the diagram. The laser beam passes through the hole 330 (not visible) between the collection optics 310 , 320 . The laser beam then reflects off a bar code (not shown) beyond the right side of the diagram and travels back toward the collection optics 310 , 320 . The reflected laser signal is transmitted through the front surfaces 418 , 428 of the collection optics 310 , 320 and then reflects off the back surfaces 419 , 429 of the collection optics 310 , 320 before striking the photodiodes located on flexible circuits 315 , 325 .
The optical collection imagers 310 , 320 in FIGS. 3 and 4 use mirrors to fold the reflected rays within a compact space. Alternatively, the optical collection imagers 310 , 320 may use lenses rather than mirrors where the photodetectors are positioned on the opposite side of the lens from the bar code or other indicia.
FIG. 5 shows suitable, relative dimensions of the active areas of the photodiodes used in a suitable optical sensor 500 with the example 300 and the resulting pattern of the photodiodes on a photodiode chip 550 . Two of the sensors 500 are used with the example 300 , one on each of the flexible circuits 315 , 325 . There are three photodiodes 510 , 520 , 530 in the sensor 500 , similar to the photodiodes described in diagram 250 . In this example, the middle photodiode 520 is the only one of the three photodiodes to receive the laser signal reflected off the bar code, but all three photodiodes 510 , 520 , 530 receive the parasitic ambient light. The lengths of the three silicon photodiodes 510 , 520 , 530 are approximately equal, having a length of 5.6 mm in the prototype. However, while the width of the middle photodiode 520 is 0.6 mm, the widths of each of the top 510 and bottom 530 photodiodes are 0.3 mm. Thus, the area of the middle photodiode 520 that receives the laser signal is approximately the same as the total of the areas of the top and bottom photodiodes 510 , 530 that only receive the parasitic ambient light.
Electric current generated by photodiode 520 has two components, current from the reflected laser signal and current from the ambient light. Because the active area of photodiode 520 is approximately equal to the sum of the active areas of the photodiodes 510 , 530 , the current generated by photodiode 520 due to the ambient light is approximately equal to the total current generated by the ambient light by photodiodes 510 , 530 . The example electrical circuit 600 shown in FIG. 6 may be used to subtract out or remove the current component generated by the ambient light from the current component generated by the laser bar code signal at photodiode 520 to obtain just the desired bar code signal. In one example, the currents generated by the two photodiodes 510 , 530 are combined, and the two photodiodes 510 , 530 are represented by a single photodiode circuit element 612 in the circuit diagram 600 . The photodiode 520 is represented by the photodiode circuit element 610 . Note that two of the electrical circuits 600 will be used with the example 400 , one for each set of three photodiodes on the flexible circuits 315 , 325 , and the outputs of the two circuits 600 are combined. In a different example, the current from the two middle photodiodes would be combined, and the currents from the two top photodiodes and the two bottom photodiodes would also be combined; the latter currents would then be subtracted from the former currents using a single electrical circuit 600 .
Both photodiode circuit elements 610 , 612 are DC-biased through resistors, transistors, or impedance elements 620 , 622 , 624 , 626 . The currents of the photodiode elements 610 , 612 pass through the capacitors 630 , 640 , 650 , 660 located near the input terminals of the amplifier 640 . Consequently, unwanted parasitic current generated by the photodiode 520 (or equivalently the photodiode circuit element 610 ) is effectively amplified and cancelled electronically at the output to the amplifier 640 without the introduction of any additional noise or the use of any other amplifiers or circuits that might decrease the signal to noise ratio. Moreover, because the same optical collector operates upon the same local field, the efficiency of the cancellation of the parasitic ambient light is maximized.
It should be noted that the amount of current generated by parasitic ambient light actually removed from the current generated by the photodiode 520 by circuit 600 depends upon the level of the signal detected by the photodiode 520 relative to the levels of the signals detected by the other photodiodes 510 , 530 , and the signal detected by the photodiodes 510 , 520 , 530 depends upon the spatial efficiency of the optical collection imagers used to image the light onto the photodiodes and the surface reflection coefficients of the bar code and the area near the bar code. For the dimensions of the photodiodes in the prototype 500 , where the photodiodes 510 , 530 are approximately half the width of the photodiode 520 , spatial efficiency variations are very small. Also, typically the surfaces above and below the bar code usually have the same reflection coefficient as the bar code itself. Thus, the configuration of the photodiode prototype 500 may be a preferred implementation in certain situations.
It will be apparent to a person skilled in the art that other dimensions and configurations of the photodiode active areas and/or different ratios of the width to the length of the photodiode active areas may be used. For example, in FIG. 7 , an alternative sensor configuration 700 is shown. A bar code or other indicia may be raster scanned by a laser onto a two-dimensional sensor 710 located on the image plane. The two-dimensional sensor 710 may be a CMOS-based sensor. The two-dimensional sensor 710 may be surrounded by smaller area photodetectors 720 , 730 , 740 or point photodetectors 750 , 751 , 752 that collect ambient light without collecting the laser light reflected from the bar code. It will also be apparent that any number of photodiode areas used for imaging ambient light may be used in conjunction with the photodiode area imaging the laser light reflected off the bar code, following the guidelines given above with respect to the surface area, spatial efficiency, and reflection coefficients. Also, the active areas of the detectors for detecting the laser signal and for detecting just parasitic ambient light need not be equal, but other electrical or optical accommodations would be necessary. Further, other electrical circuit configurations may also be used to cancel the photodiode current generated by the parasitic ambient light.
FIG. 8 depicts a flow diagram illustrating a suitable process 800 for reading an indicia and rejecting ambient light. At block 805 , the system illuminates the indicia to be read with a light source. The light source can be either a laser or non-laser source. In one example, the light source can be focused and scanned over the indicia.
At block 810 , the system images the light reflected from a first area immediately surrounding and including the indicia onto the active area of a primary photodetector using imaging optics. The light reflected from the first area includes light reflected from the indicia and also parasitic ambient light. Then at block 815 , the primary photodetector converts the imaged light to a primary electric current.
In parallel to the imaging performed by the system at block 810 , at block 812 , the system can use the same imaging optics to image ambient light from one or more additional areas near the indicia that should not be overlapping the first area onto one or more secondary photodetectors. Because the ambient light is substantially spatially independent, the ambient light per unit area imaged from the first area is substantially the same as the ambient light per unit area imaged from the one or more additional areas near the indicia that do not overlap the first area. Note that if the system uses a non-laser source to illuminate the indicia, the non-laser source should be focused by the system such that no light from the source is imaged onto the secondary photodetectors.
Then at block 817 , the secondary photodetectors each convert the ambient light that impinges on their respective active areas into secondary electric currents. A processor adds up all of the secondary electric currents generated by the secondary photodetectors at block 820 .
At block 825 the system calculates a multiplier for weighting the summed secondary currents. The multiplier is calculated by dividing the active area of the primary photodetector by the sum of the active areas of the secondary photodetectors. In some instances, the multiplier can also be dependent upon the spatial efficiency of the imaging optics and/or the surface reflection coefficients of the indicia and the areas near the indicia. At block 830 , the system weights the sum of the secondary electric currents obtained in block 820 by the multiplier obtained in block 825 .
At block 835 , the system subtracts the weighted secondary electric current sum from the primary electric current to obtain the electric current generated by the light reflected from the indicia, free of the influence of ambient light. At block 840 , the system optionally amplifies the signal current for further processing. The process 800 ends at block 899 .
The words “herein,” “above,” “below,” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word “or,” in reference to a list of two or more items, covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.
The above detailed description of examples of the invention is not intended to be exhaustive or to limit the invention to the precise form disclosed above. While specific embodiments of, and examples for, the invention are described above for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. For example, while a laser bar code reader for reading bar codes is mentioned, any desired target indicia may be scanned or imaged under the principles disclosed herein, such as alphabetic, numeric, or CJK (Chinese, Japanese, Korean language character sets) characters. Further any specific numbers noted herein are only examples: alternative implementations may employ differing values or ranges.
The teachings of the invention provided herein can be applied to other systems, not necessarily the system described above. The elements and acts of the various examples described above can be combined to provide further examples.
While the above description describes certain examples of the invention, and describes the best mode contemplated, no matter how detailed the above appears in text, the invention can be practiced in many ways. Details of the system may vary considerably in its implementation details, while still being encompassed by the invention disclosed herein. As noted above, particular terminology used when describing certain features or aspects of the invention should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the invention with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the invention to the specific examples disclosed in the specification, unless the above Detailed Description section explicitly defines such terms. Accordingly, the actual scope of the invention encompasses not only the disclosed examples, but also all equivalent ways of practicing or implementing the invention under the claims.
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A system and method of reading an indicia and rejecting ambient light is disclosed. An imaging signal and an ambient signal are received by the system where the imaging signal corresponds to indicia information and a first portion of the ambient light, and the ambient signal corresponds to a second portion of the ambient light. The imaging signal and the ambient signal are mathematically manipulated to subtract the contribution of the first portion of the ambient light from the imaging signal.
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BACKGROUND OF THE INVENTION
A conventional float valve assembly stops water flow by means of a float valve, but the resisting disc of rubber in the valve has rather little resisting force against the water pressure when the water pressure is large. So it can hardly keep water from leaking in a water tower, and as the result the water in the water tower often overflows. Such a conventional float valve can get out of order quite easily, especially, if it cannot efficiently cope with a high water pressure, as its method of stopping water is against the water flowing direction.
SUMMARY OF THE INVENTION
This invention concerns an improved structure for a float valve assembly. It includes a valve body able to connect with a water pipe and provided with an inlet, an outlet, an inwardly protruding circular edge at the outlet for a resisting disc and an anti-leak gasket to lean against, a pair of ears set at the upper outside of the outlet for uniting a moving member which also can be connected with a float rod. The float rod connected with a float at one end can turn up or down with a pin connected with the other end as an axis to move the moving member whose protruding-down foot then can pull forward or backward a cap connected with a resisting disc in the valve body with the result that the outlet can be either closed or opened by the resisting disc. The important point is that when the resisting disc closes the outlet, the flowing direction of the water is the same as the moving direction of the resisting disc in closing so that the water pressure can help the resisting disc close the outlet more tightly.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an expoded perspective view of the first example in this invention.
FIG. 2 is a cross-sectional view of the first example under the situation wherein the water is being stopped.
FIG. 3 is a cross-sectional view of the first example under the situation wherein the water is flowing out.
FIG. 4 is an exploded perspective of the second example in this invention.
FIG. 5 is a cross-sectional view of the second example under the situation wherein the water is stopped.
FIG. 6 is a cross-sectional view of the second example under the situation wherein the water is flowing out.
DETAILED DESCRIPTION OF THE INVENTION
First, this new structure for a float valve assembly includes valve body 1, float rod 2 and resisting disc 3 as the main parts as shown in the FIG. 1.
Valve body 1 made of metal is provided with male thread 11 for a water pipe to unite with, inlet 12 and outlet 13 for water to flow in and out.
Inwardly protruding circular edge 14 is provided at outlet 13 for anti-leak gasket 31 to lean against in order to prevent water from leaking out; a pair of ears 15 with round holes 16 are provided at the upper outside of outlet 13 for inspection of and pin 17 also inserts through axis hole 181 of moving member 18 which is thus united with valve body 1 and able to turn with pin 17 as an axis. Moving member 18 is also provided with tooth disc face 182 for engagement with tooth disc face 21 set at one end of float rod 2 and screw hole 184 bored at the center of tooth disc face 182 receives screw 185 to combine tightly together tooth disc faces 182 and 21. Moving member 18 is also provided with foot 183 extending downward, which can be inserted through rectangular hole 321 of cap 32, and thus move cap 32.
Next, float rod 2 is provided at one end with tooth disc face 21 which engages tooth disc face 182 of moving member 18, and round hole 24 bored at the center of tooth disc face 21 receives screw 185 to join float rod 2 and moving member 18 as one unit; thus the angle of float rod 2 between the water surface can be altered so as to control the height of the water surface in the water tower.
Float 23, which is able to float on a water surface and to be filled with some water, is combined with lid 25 with the coupling of threads, anti-leak gasket 26, placed against lid 25, can prevent the water from leaking out of float 23 and lid 25 is also combined with float rod 2 by means of female threads with the result that float 23 is also combined with float rod 2.
Resisting disc 3 to be placed inside valve body 1 is provided at its center with post 33 extending through anti-leak gasket 31, which is adhered to resisting disc 3, and and protrudes out of outlet 13, and post 33 has threads 34 at its front end to unite with cap 32. Anti-leak gasket 31, which has a larger area than outlet 13 functions to cover up outlet 13 for stopping water from flowing into the water tower. Cap 32 is provided with rectangular hole 321 for foot 183 of moving member 18 to insert through and to pull cap 32 back or forth in a limited distance.
Next, the first example of this float valve assembly shown in FIG. 2 is under the position that the float valve is closed, stopping water. Under this position float 23 has been raised up by the water surface in the water tower to the level that float rod 2 turning upward with pin 17 as the axis causes moving member 18 to turn at the same time to the extent that its foot 183 acquired a force to pull outward (or forward) as the arrow in FIG. 2 shows. Then cap 32 pulled outward by moving member 18 could pull resisting disc 3 which in turn pushed anti-leak gasket 31 to cover up inwardly protruding edge 14 of outlet 13, and the water pressure exerts a pressure against resisting disc 3 as shown by the arrow in the figure with the result that the flow stopping function of resisting disc 3 and anti-leak gasket 31 against outlet 13 can be reinforced.
Next, FIG. 3 shows this float valve assembly under the position that the float valve is opened. Under this position float 23 has fallen down owing to its own weight together with the water surface in the water tower to such a level that resisting disc 3 and anti-leak gasket 31 are pushed inward (or backward) to open outlet 13, allowing water flow out of outlet 13 by cap 32 which was pushed by foot 183 of moving member 18 turned by float rod 2 having turned down with pin 17 as the axis by the movement of float 23.
The improved structure of the first example shown in FIGS. 1, 2 and 3 is applied to those to be connected to the water pipe of less than one inch diameter, and the structure of the second example shown in FIGS. 4, 5 and 6 is applied to those used for a larger water pressure. The structure of the second example is almost the same except the structure of resisting disc 3 and the setting of lid 19. Next, the second example is to be described.
Valve body 1 made of metal is provided with thread 11 to connect with a water pipe, inlet 12 and downstream opening 53. Female thread 14 is provided at opening 53 for uniting lid 19, which has outlet 191 corresponding to outlet 13 of FIGS. 1-3, inwardly protruding circular edge 192 and a pair of ears 15 at its upper outside. Ears 15 have round holes for receiving pin 17 for combining lid 19 with moving member 18 whose axis hole 181 also receives pin 17. Moving member 18 is also provided with tooth disc face 182 to engage with tooth disc face 21 of float rod 2 and both tooth disc faces 182, 21 are tightly screwed together with screw 185 inserted in screw hole 182 and round hole 24, so both moving member 18 and float rod 2 are tightly united and moved as one unit. In addition, moving member 18 is also provided with foot 183 extending downward for insertion through rectangular hole 321 of cap 32. And anti-leak gasket 10 is placed between lid 19 and valve body 1 to attain better anti-leak function.
Next, float rod 2 is also provided at one end with tooth disc face 21 to engage with tooth disc face 182 of moving member 18, and with thread 22 to unite with lid 25 of float 23 which can also store some water to increase its own weight.
Resisting disc 54 is a little different from disc 3 of the first example having at its top ear 35 a hole for insertion of pin 36, which also inserts through ear 193 provided at the inside of lid 19. The setting of lid 19 is also the difference from a first example, wherein lid 19 does not exist. Resisting disc 54 also has post 55 extending through the center of anti-leak gasket 321 with its threaded end united with cap 32.
When float 23 has been raised up as shown in FIG. 5 by the water surface in a water tower to a certain level, float rod 2 can turn upward with pin 17 as the axis, and foot 183 can then be given a force to pull outward cap 32, which in turn pulls resisting disc 54 to urge anti-leak gasket 31 tightly against protruding edge 192 of outlet 191, and then the water is stopped. Moreover, the greater the water pressure in the water pipe, the better the anti-leak function of resisting disc 54.
On the contrary, as shown in FIG. 6, when float 23 has fallen down owing to its own weight with the water surface to a certain level, float rod 2 can turn down with pin 17 as the axis causing foot 183 of moving member 18 to move inward and resisting disc 54 and anti-leak gasket 31 also interrelatingly to move inward to leave outlet 191 so that the water in the valve can flow out of outlet 191 into the water tower.
In general, the structure of this invention utilizes the flowing direction of the water in the pipe in stopping water, so the larger the water pressure, the better the anti-leak effect. Consequently, overflow from a water tower will never happen, if this invention is used.
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An improved structure for a float valve assembly, utilizing a resisting disc which can be urged against or open the water outlet of the valve to stop or open the water flowing passage by the interrelated movement of a float, a float rod, a moving member, a cap and the resisting disc. The flowing direction of the water in the valve, i.e. the water pressure, can help push the resisting disc in covering up the outlet so the water flow can be stopped more easily and more effectively.
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This is a division, of application Ser. No. 763,682 filed Sep. 23, 1991, now U.S. Pat. No. 5,166,436.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for the preparation of N-ethylhydroxylamine hydrochloride. More particularly, this invention relates to a novel, safe process for the preparation of N-ethylhydroxylamine hydrochloride from di-t-butyl dicarbonate (BOC anhydride) and hydroxylamine hydrochloride.
N-ethylhydroxylamine hydrochloride is useful in the preparation of pharmaceutical intermediates.
2. Background Art
The preparation of N-ethylhydroxylamine is well known, however, the preparation of this product from N,O-bis[(1,1-dimethylethoxy)-carbonyl]-hydroxylamine intermediates is novel.
Louis Carpino et al. in the Journal of the American Chemical Society, Vol. 81, 1959, pp. 955-957 discloses the synthesis of N and N,O-bis[(1,1-dimethylethoxy)carbonyl] hydroxylamine using t-butyl azidoformate. T-butyl azidoformate is no longer used as it is a thermally unstable, shock sensitive compound which is too hazardous for any small or large scale uses, and is no longer commercially available for these reasons.
Harris et al. in Tetrahedron Letters, Vol. 24, 1983 pp. 231-32, discloses a new type of compound that can be used to acylate amines. This paper teaches the use of di-tert-butyl dicarbonate with hydroxylamine to prepare t-butyl aminocarbonate. However, the N,O-bis product was not obtained, only the O-substituted and N-substituted acylated products.
SUMMARY OF THE INVENTION
In accordance with this invention, a method is provided for preparing N-ethylhydroxylamine according to the following reaction: ##STR1##
A significant advantage of the process of the invention is the preparation of N-ethylhydroxylamine in high yield and purity.
DETAILED DESCRIPTION OF THE INVENTION
Hydroxylamine hydrochloride is added to a base such as sodium carbonate, potassium bicarbonate or sodium or potassium hydroxide in a non-reactive solvent such as water, dichloromethane or dioxane, then treated with di-t-butyl dicarbonate added over a period of 30 minutes to 6 hours at 10° to 60° C. Unexpectedly, N,O-bis-BOC-hydroxylamine is isolated. This is unexpected because the literature suggests that the N,O-bis product is only available when the hydroxylamine hydrochloride is reacted with t-butyl azidoformate.
The pH of the solution is adjusted such that it is a basic solution with a pH between 7 to 11. Any of the aforementioned bases can be used and the pH depends on the choice of base.
The reaction can be run with any solvent that will not react with the base or di-tert-butyl dicarbonate. Therefore it is preferred that primary or secondary amines, alcohols or thiols not be used. Water is the preferred solvent.
The N,O-bis-BOC-hydroxylamine is isolated following extraction with toluene, concentration with azeotropic removal of t-butanol and crystallization from hexane.
The N,O-bis-BOC-hydroxylamine can be alkylated in the following manner. The product, in DMF, is treated with a base such as potassium or sodium carbonate or potassium-t-butoxide or other alkali metal alkoxides and an alkylhalide such as ethyl iodide or ethyl bromide. This alkylation reaction is typically conducted at a temperature of 0° to 70° C., for 15 minutes to 6 hours. Preferably, the reaction is conducted at a temperature range of 25° to 35° C. for 30 minutes to 1 hour. The temperature of the alkylation step is controlled by the boiling point of the alkylating agent.
N-ethyl-N,O-bis-BOC-hydroxylamine is isolated as an oil following dilution with water, extraction and concentration in vacuo.
This oil, in ethyl acetate, is treated with HCl or other suitable acids at 30° to 40° C. for 30 minutes to 3 hours to cleave the N,O-bis-BOC portion of the compound to yield N-ethylhydroxylamine hydrochloride in high yield, when anhydrous HCl is used. In order to smoothly cleave the BOC group, a large amount of hydrochloric acid is required. Greater than 2 equivalents of the HCl is required to cleave the BOC group. The amount of HCl is within a range of 2 to 7 equivalents with the preferred range being between 5 and 6 equivalents of the acid.
The ratio of the reactants in the first step is two moles of the BOC catalyst per mole of hydroxylamine hydrochloride. However, the reaction can be run at a ratio of up to 3 moles of the BOC catalyst per mole of hydrochloride without significant decrease in yield.
The inventive method may be further illustrated by the following example. All parts, proportions, ratios and percentages are by weight unless otherwise indicated.
EXAMPLE 1
a. Conversions of hydroxylamine hydrochloride to N,O-bis-BOC-hydroxylamine
Hydroxylamine hydrochloride (1 mole) is added to Na 2 CO 3 (1.25 moles) in H 2 O (500 ml) then treated with di-t-butyl dicarbonate (BOC) (2.0-2.2 equiv) added over 3 hours at 35°-40° C. Following extraction with toluene (2:1 v/v), concentration with azeotropic removal of t-butanol and crystallization from hexane (1:1 v/v), N,O-bis-BOC-hydroxylamine, m.p. 70°-72° C., is isolated in high yield. The product from 3 similar reactions was combined and recrystallized from hexane to give 629 g of purified product.
b. Alkylation to N-ethyl-N,O-bis-BOC-hydroxylamine
N,O-bis-BOC-hydroxylamine (1.35 mole) in dimethylformamide (3:1 v/v) is treated with potassium carbonate (1.25 equiv, milled) and ethyl iodide (1.025 equiv). The ethyl iodide is added over 3/4 hour at 30° C. Complete conversion to N-ethyl-N,O-bis-BOC-hydroxylamine was observed by thin layer chromatography at 30 minutes/30° C. following addition of the ethyl iodide. The product (704.7 g) is isolated as an oil from 2 similarly run reactions following dilution with H 2 O (8:1 v/v), extraction with toluene (2:1 v/v), washing with water (4×3:1 v/v) and concentration in vacuo.
c. Cleavage to N-ethylhydroxylamine hydrochloride
N-Ethyl-N,O-bis-BOC-hydroxylamine (1.35 mole), in ethyl acetate (3:1 v/v), is treated with HCl (5.5 equiv, anhy.) at 37° C. added over 13/4 hours. The product was concentrated in vacuo to give 129.8 g of N-ethylhydroxylamine hydrochloride in high yield.
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A process for preparing N-ethylhydroxylamine hydrochloride which comprises reacting hydroxylamine hydrochloride with di-t-butyl dicarbonate in the presence of a base thus producing N,O-bis-[(1,1-dimethylethoxy)carbonyl]-hydroxylamine, alkylating said reaction product and then cleaving with acid the tert-butyloxy carbonyl (BOC) portion of the alkylated product.
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RELATED APPLICATIONS
The present application is a continuation of application Ser. No. 07/286,477, filed Dec. 19, 1988, now abandoned, which is a continuation-in-part of application Ser. No. 766,852, filed Aug. 16, 1985 now abandoned, which is a continuation-in-part of Ser. No. 414,098, filed Sep. 7, 1982, now U.S. Pat. No. 4,603,106, issued Jul. 29, 1986, which is in turn a continuation-in-part of Ser. No. 351,290, filed Feb. 22, 1982, now abandoned, which is in turn a continuation-in-part of Ser. No. 299,932, filed Sep. 8, 1981, also abandoned, in all of which at least one of the Applicants herein is a co-inventor. Applicants claim the benefit of these applications under 35 U.S.C. Section 120.
RELATED PUBLICATIONS
The Applicants are authors or co-authors of several articles directed to the subject matter of the present invention. These articles are in supplementation to those articles listed in U.S. Pat. No. 4,603,106, which earlier articles are incorporated herein by reference. (1) Applicant Cerami co-authored with B. Beutler, J. Mahoney, N. Le Trang and P. Pekala! "Purification of Cachectin, a Lipoprotein Lipase-Suppressing Hormone Secreted By Endotoxin-Induced RAW 264 7 Cells", J. EXP. MED. 161 at 984-995 (May, 1985); (2) Applicant Cerami co-authored with J. R. Mahoney, B. Beutler, N. Le Trang, W. Vine, and Y. Ikeda! "Lipopolysaccharide-Treated RAW 264.7 Cells produce a Mediator Which Inhibits Lipoprotein Lipase in 3T3-L1 Cells", J. IMMUNOL. 134 (3) at 1673-1675 (March, 1985); (3) Applicant Cerami co-authored with P. J. Hotez, N. Le Trang, and A. H. Fairlamb! "Lipoprotein Lipase Suppression in 3T3-L1 Cells by a Haematoprotozoan-Induced Mediator From Peritoneal Exudate Cells", PARASITE IMMUNOL. (Oxf.) 6:203 (1984); (4) Applicant Cerami co-authored with B. Beutler, D. Greenwald, J. D. Hulmes, M. Chang Y.-C. E. Pan, J. Mathison and R. Ulevitch! "Identity of Tumor Necrosis Factor and Macrophage-Secreted Factor Cachectin", NATURE 316:552-554, (1985); (5) Applicant Cerami co-authored with B. Beutler, F. M. Torti, B. Dieckmann and G. M. Ringold! "A Macrophage Factor Inhibits Adipocyte Gene Expression: An In Vitro Model of Cachexia", SCIENCE 229:867-869, (1985); (6) Applicant Cerami co-authored with B. Beutler and I. W. Milsark! "Passive Immunization Against Cachectin/Tumor Necrosis Factor (TNF) Protects Mice From the Lethal Effect of Endotoxin", SCIENCE 229:869-871, (1985); (7) Applicants Cerami and Wolpe co-authored with K. J. Tracey, B. Beutler, S. F. Lowry, J. Merryweather, I. W. Milsark, R. J. Hariri, T. J. Fahey III, A. Zentella, J. D. Albert and G. T. Shires! "Shock And Tissue Injury Induced By Recombinant Human Cachectin", SCIENCE 234:470-474 (1986); and (8) Applicant Cerami co-authored with K. J. Tracey, Y. Fong, D. G. Hesse, K. R. Manogue, A. T. Lee, G. C. Kuo and S. F. Lowry! "Anti-Cachectin/TNF Monoclonal Antibodies prevent Septic Shock During Lethal Bacteraemia", NATURE 330:662-664 (Dec. 17, 1987). All of the above listed articles are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention is directed to new hybrid cell lines and more specifically to hybrid cell lines for production of monoclonal antibody to cachectin/TNF, to the antibody so produced, to antibodies raised thereto, and to diagnostic and therapeutic methods and compositions employing these antibodies.
The development of monoclonal antibodies has made possible new diagnostic and therapeutic techniques. Monoclonal antibodies are homogeneous immunoglobulins of well-defined chemical structure in contrast to polyclonal antibodies which are heterogeneous mixtures of immunoglobulins. A characteristic feature of monoclonal antibodies is high specificity and reproducibility of function.
The technique for producing monoclonal antibodies from hybridized cells (hybridomas) was first described by Kohler and Milstein NATURE 256:495-497 (1975)!. The hybridomas are produced by fusion of mouse myeloma cells with spleen cells from immunized mice or rats. Clones of the hybridoma cells (cells arising from a single parent plasmacytoma spleen fusion cell) are then tested for their ability to produce the desired monoclonal antibody. Each clone produces only a single antibody type directed against a single antigen only and is therefore highly specific. In contrast to conventional (polyclonal) antibody preparations which typically include different types of antibodies directed against different sets of determinants (sites) on the same antigen, monoclonal antibody preparations are directed only against a single determinant.
Although the general procedures for preparing hybridomas are known, there is no certainty that the desired hybridoma will be obtained, that the hybridoma obtained will produce the desired antibody and that the antibody obtained will have the desired degree of specificity. The level of success is chiefly dependent upon the type of antigen employed during the immunization procedure and the selection technique employed for isolating the desired hybridoma.
One of the areas of interest for using monoclonal antibodies is in the diagnosis and treatment of biochemical derangements that occur in mammalian hosts responding to invasive stimuli. These gross imbalances of host physiology are generally manifested as a wasting of the body (cachexia) which itself may threaten the integrity of the host. These metabolic disorders seem to be mediated largely by the immune system. For example, in response to invasive stimuli, the reticuloendothelial cells and lymphocytes secrete cytokines which are capable of altering host metabolism. These cytokines include for example, Interleukin-1, Interleukin-2, lymphotoxin, gamma-interferon and the substance known as either cachectin or tumor necrosis factor (TNF).
Systemic deficiency of the anabolic enzyme lipoprotein lipase (LPL) activity has been observed in cachectic animals. Deficiency of LPL activity has also been observed in mice after administration of endotoxin (lipopolysaccharide, LpS). In contrast, deficiency of LPL activity has not been observed in mice genetically resistant to LPS. Resistance to endotoxin-induced LPL deficiency could be overcome by administration of serum obtained from endotoxin-sensitive animals which had been previously injected with LPL. The active factor in this serum was termed "cachectin" because of its involvement in the pathogenesis of cachexia M. Kawakami et al., PROC. NATL. ACAD. SCI., (USA), 79:912-916 (1982)!.
The existence of a factor which caused hemorrhagic necrosis of tumors, in the serum of endotoxin-treated animals previously infected with Mycobacterium bovis strain Bacillus Calmette-Guerin was also observed. The active principal in this serum was termed "tumor necrosis factor" E. A. Carswell et al., PROC. NATL. SCI. (USA), 72:3666-3670 (1975)!.
The potent tumor necrosis factor activity of cachectin in vitro and DNA sequencing of the primary structure of cachectin and tumor necrosis factor confirmed that these polypetides are homologous molecules and that their bioactivities are both derived from a highly conserved protein. Accordingly, the term "cachectin/TNF" will be used when referring to these factors herein.
Cachectin/TNF is a polypeptide hormone composed of subunits having a relative molecular mass of 17,000 arranged in dimeric, trimeric or pentameric form depending upon the species and the method of isolation. When administered to animals in moderate amounts, cachectin/TNF induces a state of anorexia and ensuing weight loss. Cachectin/TNF also seems to play a major role in the pathogenesis of Gram-negative (endotoxin-induced) shock. Not only does the administration of large doses of cachectin/TNF directly mimic the clinical syndrome produced by endotoxemia K. J. Tracey et al., SCIENCE 234:470-474 (1986)!, but passive immunization against cachectin/TNF substantially mitigates the lethal effect of endotoxin K. J. Tracey et al., NATURE 330:662-664(1987)!. Cachectin/TNF has the ability to substantially suppress the activity of the anabolic enzyme LPL and is capable of preventing the differentiation of fat cells and increasing the uptake of glucose in muscle cells. Cachectin/TNF demonstrably lacks leukocyte activator activity which characteristic distinguishes it from Interleukin-1. Similarly, the ability of cachectin/TNF to significantly suppress LPL activity distinguishes it from Interleukin-2. These findings were set forth in copending parent application Ser. No. 766,852, the disclosure of which is incorporated herein by reference.
Most cell types express specific high-affinity cell-surface receptors for cachectin/TNF, but the consequences of binding the cytokine are diverse and often cell- and species-specific. Certain cell types show marked sensitivity to the cytotoxic effects of cachectin/TNF while others bind the cytokine but are not deleteriously affected. Other cell types respond to cachectin/TNF treatment with specific and well coordinated changes in the activity, expression, synthesis, or release of surface or cytosolic proteins, enzymes, or further physiological mediators. Much research over the past few years has focused on dissecting apart these differential biological effects of cachectin/TNF and an important step in this direction would be the identification and characterization of cachectin/TNF receptors from various cellular sources.
Accordingly, there exists a need for antibodies in relatively pure form for the detection and study of cachectin/TNF. More particularly, there exists a need for monoclonal antibodies to cachectin/TNF for use in the diagnosis and treatment of cachexia and related diseases.
SUMMARY OF THE INVENTION
The present invention pertains to the novel hybridoma SDW18.1.1, hybridomas obtained from SDW18.1.1, monoclonal antibodies obtained from such hybridomas, derivatives of such monoclonal antibodies and the use of such monoclonal antibodies and their derivatives of diagnostic and therapeutic methods and compositions. The novel hybridomas are formed by fusion of cells from a mouse myeloma line and spleen cells from a mouse previously immunized with cachectin/TNF.
Accordingly, it is a principal object of the present invention to prepare a monoclonal antibody to cachectin/TNF.
It is a further object of the present invention to employ the monoclonal antibody to detect and study as aforesaid the activity of cachectin/TNF.
It is a still further object of the present invention to employ the monoclonal antibody as aforesaid to diagnose and treat biological derangements in which cachectin/TNF is implicated.
It is a still further object of the present invention to prepare additional antibodies from the monoclonal antibody as aforesaid which may be used in further diagnostic and therapeutic settings because of their ability to bind to the cellular receptor for cachectin/TNF.
Other objects and advantges will become apparent to those skilled in the art from a consideration of the ensuing description.
DETAILED DESCRIPTION
The present invention concerns the preparation and use of a monoclonal antibody to cachectin/TNF. The particular monoclonal antibody prepared and discussed herein was raised against human tumor necrosis factor. It is understood however that the preparation and application of the antibody described herein extends to monoclonal antibodies based on other sources of cachectin/TNF and is therefore, intended to encompass such variations in source within its scope.
The novel monoclonal antibodies of the present invention provide a high titer, reproducible, biological reagent for the assay of cachectin/TNF. Fluids or tissues from a variety of mammals can be screened by radioimmunoassay, enzyme immunoassay, immunofluorescence, complement fixation, immunoprecipitation or any reaction which depends upon antibody recognition of antigen for the detection of cachectin/TNF. Furthermore, the novel monoclonal antibodies of the present invention are useful in the diagnosis and treatment of cachexia and related diseases.
The hybridoma SDW18.1.1 was deposited at the American Type Culture Collection, 12301 Parklawn Drive, Rockville, Md. 20852 for patent purposes as defined in M.P.E.P. 608.01(p) on Oct.15, 1986 and was given the A.T.C.C. Accession No. HB 9228.
In general, the method of preparing the hybridoma of the present invention comprises the following steps: (a) immunizing mice with cachectin/TNF; (b) removing the spleens from the mice and preparing an immunized spleen-cell suspension; (c) fusing the suspended spleen cells with mouse myeloma cells from a suitable cell line using a fusion promoter; (d) diluting and culturing in separate wells the mixture of unfused spleen cells, unfused myeloma cells, and fused hybrid cells in a selective medium which will not support the unfused myeloma cells for a time sufficient to allow the death of the unfused cells; (e) evaluating the supernatant in each well containing the hybridoma for the presence of antibodies to cachectin/TNF; and (f) selecting and cloning hybridomas producing the desired monoclonal antibodies.
The immunization schedule and the concentration of cachectin/TNF should be such that useful quantities of primed splenocytes are obtained. Freund's adjuvant may be used to prime the immune system. After centrifugation and washing, the immunized spleen cells are ready to be fused with mouse myeloma cells. Suitable fusion promoters are polyethylene glycol (PEG) and dimethyl sulfoxide (DMSO).
The myeloma cell lines chosen should preferably be the drug resistant type such as the 8-azaguanine resistant cell lines which lines are deficient in the enzyme hypoxanthine guanine ribosyl transferase (HPRT) or thymidine kinase. The lack of these specific enzymes in these lines makes it impossible for these myeloma cells to incorporate exogenously supplied hypoxanthine or thymidine. Endogenous DNA synthesis may be blocked by use of aminopterin. Thus, unfused myeloma cells will not be supported by hypoxanthine, aminopterin, and thymidine (HAT) medium. Similarly, the unfused nonmalignant immunized spleen cells have only a finite number of generations and will not survive in HAT for more than a few days. The fused hybrid cells, on the other hand, will continue to reproduce because they possess the malignant quality of the myeloma parent and are able to survive in the selective medium by virtue of metabolic pathways deriving from the spleen cell parent.
The hybridomas may be cloned using the limited dilution method or the solid gel media method. The preferred cloning method is the limited dilution method. In this method, a hybridoma suspension is proportionately divided among a series of sterile wells. Visual appearance of colonies usually takes one to two weeks. The wells having the fewest hybridomas, showing single clones, are then evaluated for antibody production.
Once the hybridoma of choice has been selected and cloned, the desired monoclonal antibody may be produced in vitro or in vivo. The purest monoclonal antibody is produced in vitro by culturing the desired hybridoma in a suitable medium for a suitable length of time followed by recovering the desired antibody from the supernatant. The suitable medium and the suitable length of culturing time are known or are readily determined. This in vitro technique produces monoclonal antibody essentially free from other nonspecific antihuman immune globulins. However, this method may not produce a sufficient quantity of a sufficient concentration of monoclonal antibody for some purposes since the concentration of antibody obtained is relatively low.
Much higher concentrations (high titer) of slightly less pure monoclonal antibody may be produced using the in vivo method. In this method, the desired hybridoma is injected into mice, preferably syngenic or semisyngenic mice, causing formation of antibody-producing tumors after a suitable incubation time. These tumors will produce a relatively high concentration of the desired antibody in the bloodstream and peritoneal exudate (ascites) of the host mouse. Although these host mice also have normal antibodies in their blood and ascites, the concentration of these normal antibodies is low and these normal antibodies are not usually antihuman in their specificity.
The hybridomas of the present invention may also be used as a source of genetic material. For example, the hybridomas may be fused with other cells to provide still other novel hybridomas having the same secretory capabilities as SDW18.1.1 and providing antibodies having the same specificity. Such fusion of the subject hybridoma to other cells may result in the production of antibodies having different heavy polypeptide chains, providing other classes or subclasses of antibodies such as IgM, IgA, IgG 2 , IgD, IgE, etc.
Although only a single novel hybridoma producing a single monoclonal antibody against cachectin/TNF antigen is described, Applicants intend the present invention to encompass all monoclonal antibodies which exhibit the characteristics described herein. The monoclonal antibody of the present invention to cachectin/TNF belongs to the subclass IgG1. The other classes and subclasses of IgG antibodies differ from one another in their "fixed" regions, i.e. areas having the same amino acid sequences. However, these antibodies will also have a "variable" region which is functionally identical, i.e. antigen specific, regardless of which antibody class or subclass to which the antibody belongs. Hence, a monoclonal antibody exhibiting the characteristics described herein may be of class IgM, IgA and so forth. Differences among these classes or subclasses will not affect the selectivity of the reaction pattern of the monoclonal antibody but may affect the reaction of the antibody with other materials. Although the antibody of the present invention belongs to class IgG1, Applicants intend that all antibodies having the patterns of reactivity illustrated herein are included within the present invention regardless of the immunoglobulin class or subclass to which they belong. Furthermore, for many applications, the entire monoclonal antibody molecule need not be used but only a fragment of the molecule having intact antigen-binding sites will suffice.
Although only a single hybridoma is described here, Applicants intend the present invention to encompass all methods for preparing the monoclonal antibodies described above employing the hybridoma technique described herein. One skilled in the art could follow the immunization, fusion, selection and cloning methods provided herein and obtain other hybridomas capable of producing monoclonal antibodies having the reactivity characteristics disclosed herein. Since the novel hybridoma produced from a known mouse myeloma cell line and spleen cells from a known species of mouse is best characterized by description of the antibody produced by the hybridoma, all hybridomas producing antibody having the reactivity characteristics described above are included within the subject invention, as are methods for making this antibody which employ the hybridoma.
It has now been found that cachectin is the principal mediator in both endotoxin-induced shock as well as tumor necrosis. Nature, Vol. 320, No. 6063, pp. 584-588, 17 Apr. 1986!Applicants have successfully shown this to be true through passive immunization of baboons against endogenous cachectin. The baboons were subsequently infused with an LD 100 dose of live Escherichia coli. Control animals (not immunized against cachectin) developed hypotension followed by lethal renal and pulmonary failure. Neutralizing monoclonal anti-cachectin antibody fragments F(ab') 2 ! administered to baboons only one hour before bacterial challenge, protected against shock but did not prevent critical organ failure. Complete protection against shock, vital organ dysfunction, persistent stress hormone release and death was conferred by administration of cachectin monoclonal antibodies 2 hours before bacterial infusion. These results indicate that cachectin is a mediator of fatal bacteremic shock, and suggest that cachectin antibodies offer a potential therapy for life-threatening infection. Thus, through passive immunization with cachectin antibodies, the deleterious effects of caohectin, such as septic shock, can be prevented or at least reduced. This invention thus contemplates a composition containing cachectin antibody for passive immunization of mammals against the effects of endotoxin. Additionally, this invention further contemplates an assay kit for the detection of human tumor necrosis factor, said kit comprising monoclonal antibody or antibody fragments reactant to cachectin, as well as other reagents and directions for use of such kit.
Accordingly, the present invention is also directed to in vivo and in vitro methods of diagnosis as well as therapy employing the monoclonal antibody to cachectin/TNF as well as anti-idiotype antibodies raised thereto. These techniques may be employed using the cachectin/TNF antibody or the anti-idiotype antibody alone, or in combination with other antibodies. For many applications, the antibodies will be labeled with a compound which imparts a detecting signal, providing cytotoxicity, providing for localizing electromagnetic radiation, or the like. Labels may include radionuclides, enzymes, fluorescent moieties, toxins or the cytoxic fragment of toxins, particles, metals, metalloids, etc. The antibodies may be incorporated in liposome membranes or modified with lipids so as to be incorporated in such membranes. The antibodies by themselves or labeled may be used in in vitro diagnosis for measuring the presence of antigens associated with cachectin/TNF, for in vivo diagnosis for introduction into a host, e.g., intravenously, in a physiologically acceptable carrier, e.g., phosphate buffered saline, or may be introduced for therapeutic purposes in the same manner. Moreover, the antibodies of the present invention may be employed in methods and compositions for assaying cachectin/TNF, for diagnosing and treating disease states such as cachexia, septic shock, and related diseases and for the preparation of passive vaccines against these diseases. The amount of antibody employed will vary depending upon the particular application. The use of antibodies for diagnostic and therapeutic purposes has been extensively described in the literature.
Treatment of disease states such as cachexia may be accomplished by administration of a therapeutically effective amount of cachectin/TNF antibody to an individual in need of such treatment. By selective reaction with cachectin/TNF antigen, the effective amount of cachectin/TNF antibody will neutralize the excess of antigen, thus ameliorating the effects of the excess, such as undesirable weight loss. Diagnostic and therapeutic compositions comprising effective amounts of cachectin/TNF antibody in admixture with diagnostic or pharmaceutically acceptable carriers, respectively, are also included within the present invention.
In addition to the discovery of the above-described hydridoma cell line and the monoclonal antibodies produced therefrom, it has also been discovered that another set of polyclonal, polyspecific antibodies can be produced which are reactive with the monoclonal antibodies described herein. These polyclonal antibodies are, in effect, antibodies against antibodies and a subset is called anti-idiotype antibodies. By introducing anti-idiotype antibodies into the cachectin/TNF-TNF receptor reaction, a competitive reaction is set up between the anti-idiotype and the cachectin/TNF molecule which may result in less binding of the cachectin/TNF molecule with its cellular receptor. Thus, the anti-idiotype antibody can block the cachectin/TNF ligand complex from binding with its receptor, thereby possibly altering the deleterious effects of cachectin/TNF.
The present invention is further illustrated by the following examples which are not intended to limit the effective scope of the claims.
EXAMPLE
Recombinant human tumor necrosis factor (hTNF) (Genentech, Inc.) was emulsified in complete Freund's adjuvant. The equivalent of 17 micrograms of hTNF was injected subcutaneously into two mice (C57B1/6×Balb/c F1 female, Charles River Kingston). One month later, the spleens of these two mice were surgically exposed and 10 micrograms of hTNF in 100 microliters of phosphate-buffered saline ("PBS") were injected into each mouse intrasplenically. The spleens were placed back into the body cavities and the incisions were closed.
Three days later, the spleens were removed and carefully teased apart in Dulbecco's modified Eagle's medium (Grand Island Biological Company, Grand Island, N.Y.) with 4.5 grams per liter glucose and.10% fetal bovine serum to yield a single-cell suspension.
These immunized spleen cells were fused with the P3-×63-Ag8.653 myeloma cell line (American Type Culture Collection) utilizing the protocol described in Monoclonal Antibodies, R. Kennett, K. Bechtol and T. McKearn (Eds.), plenum press (1980). The fused cells were plated onto macrophage feeder layers using the protocol described by Fazekas de St. Groth and Scheidegger, J. Immunol. Methods, 35,1-21 (1980), and allowed to grow until macroscopic colonies were observed.
Colonies were tested for the production of antibody against hTNF using an immunoblotting assay. Nitrocellulose sheets were immersed in PBS and blotted dry. A quantity of 5 microliters of hTNF (initially obtained from Genentech, Inc., and later obtained from Chiron Corp.) at a concentration of 0.1 microgram per milliliter were dotted onto spots on the nitrocellulose plate through wells in a Bio-Rad dot-blotting apparatus. The nitrocellulose was blocked using a solution of 1% bovine serum albumin in PBS. A quantity of 100 microliters of the supernatant above the cultured hybridoma colonies was added to each dot-blot and well, and incubated for 45 minutes. The clones which reacted positively were visualized by the subsequent use of a VECTASTAIN (trademark) avidin-biotin-peroxidase system (Vector, Inc.) according to the instructions of the manufacturer.
Initially, thirteen positive clones were identified. Four clones appeared to show false positives because they also showed positive in the absence of antigen. One clone (#23) showed positive with antigen material obtained from Genentech, Inc. but not with antigen material obtained from Chiron Corp. Four clones (#27, #37, #42 and #156) appeared to lose activity during further propagation. These four clones and three other clones (#299, #433 and #471) were set aside for further characterization.
One clone (#18) exhibited consistent reactivity and retained this reactivity during subcloning. Subcloning was achieved by limited dilution on macrophage feeder layers. Dilute suspensions of a given clone were plated onto 96-well plates such that less than a third of the wells were positive for growth.
Each subcloning was designated by a period. Hence, the designation --18.1.1--means that clone #18 was subcloned twice and the first well which showed growth was chosen for further subcloning each time. The subject hybrid antibody was demonstrated by standard techniques to be of class IgG1.
This invention may be embodied in other forms or carried out in other ways without departing from the spirit or essential characteristics thereof. The present disclosure is therefore to be considered as in all respects illustrative and not restrictive, the scope of the invention being indicated by the appended Claims, and all changes which come within the meaning and range of equivalency are intended to be embraced therein.
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The present invention pertains to the novel hybridoma SDW18.1.1, hybridomas obtained from SDW18.1.1, monoclonal antibodies obtained from such hybridomas and derivatives of such monoclonal antibodies. The novel hybridomas are formed by fusion of cells from a mouse myeloma line and spleen cells from a mouse previously immunized with cachectin/TNF. Diagnostic and therapeutic utilities for the monoclonal antibodies and their derivatives are proposed, and testing procedures, materials in kit form and pharmaceutical compositions are likewise set forth.
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CROSS REFERENCES TO RELATED APPLICATIONS
None
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT
Not Applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a rear blade mounting apparatus for a bulldozer. In particular, the invention relates to a blade apparatus and its control method, which blade is mounted to the rear of the bulldozer such that the rear blade can be operated in lift or tilt modes.
2. Brief Description of Prior Art
In the construction industry, labor and capital equipment costs are primary variables that effect the cost of a particular project. Large machinery is used to more efficiently handle tasks that were originally accomplished by hand, such as digging, lifting, and moving objects. For example, bulldozers are commonly used on construction job sites for digging, pushing and removing large amounts of earth for mining, grading and other tasks.
A bulldozer is typically a tractor-like machine having a forwardly mounted bucket that extends forward of the body of the bulldozer. The bulldozer further includes a pair of extending loader arms pivotally connected to the tractor, and said bucket pivotally mounted on free ends of the loader arms. Hydraulic cylinders, or the like, are mounted on the loader arms and controlled to cause the bucket to be positioned in various desired positions. The bucket can be lifted over the body or placed on the ground. Further, the orientation of the bucket can be controlled to hold dirt or the like or to dump the same.
The rear of the tractor may include an attachment that trails the body of the bulldozer such as a ripper, or a winch, or the rear of the tractor may not include any such accessory.
While these tractors in general, are effective in collecting and removing earth, especially large chunks of earth, these tractors have some limitations. In particular, a conventional bulldozer having said forwardly mounted bucket when collecting and removing earth from a mine pit for example, cannot pivot so that the bucket will collect the fine material remaining at or near the walls of such pit. Depending upon the size of the pit, there are often large volumes of such materials remaining. Often such remaining material must be shoveled by hand into a dump truck for transporting away. Such manual procedure requires additional manpower which is not only dangerous due to such manpower working near large machinery, but also costly, time consuming, and generally inefficient. The inventor herein is unaware of any attachment to the bulldozer available for collecting such materials at or near the walls of the mine pit work site.
As will be seen from the subsequent description, the preferred embodiments of the present invention overcome these and other shortcomings of prior art.
SUMMARY OF THE INVENTION
The present invention is designed to be mounted to the rear of a bulldozer that will effectively access and make collectable materials such as fine material remaining at or near the walls of a mine pit for example, that the front-end bucket of the bulldozer is unable to access. The preferred embodiment generally includes a frame that extends from the rear of the body of the bulldozer, said frame including a pair of extending loader arms pivotally connected to the rear of the bulldozer, and a blade pivotally mounted on free ends of the loader arms, and hydraulic cylinders, or the like, controlled to cause the blade to be positioned in various desired positions.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view of a bulldozer having rearwardly mounted the preferred embodiment of the present invention, where the blade is in a first position.
FIG. 2 is a side view of the bulldozer of FIG. 1 where the blade is in a second position.
FIG. 3 illustrates a perspective view of the frame of the present invention.
FIG. 4 illustrates a perspective view of the blade of the present invention.
FIG. 5 illustrates a partial view of the bulldozer with the blade in a third position.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIGS. 1–5 illustrate a preferred embodiment of a bulldozer rear blade mounting structure 50 made in accordance with the present invention. With reference to FIGS. 1–2 , a common bulldozer tractor 10 (also referred to as a tractor 10 ) having the prior art forwardly mounted bulldozer structure 12 having a bucket 15 secured to the front of the tractor 10 is disclosed.
As shown in FIGS. 1–2 , attached to the rear of the tractor 10 is the rear blade mounting structure 50 made in accordance with the present invention. The structure 50 includes a frame 55 , said frame 55 , as best shown in FIG. 3 , having first and second support arms 55 A and 55 B. The support arms 55 A and 55 B extend from the rear of the body of the tractor 10 and is pivotally mounted to the rear of the body of the tractor 10 in a manner using, connecting pivot points 57 A (not shown) and 57 B (shown in FIG. 5 ). The opposite ends of support arms 59 A and 59 B of the support arms are coupled to midway end portions 65 A and 65 B of the inside of a blade 60 . The blade 60 having a blade edge member 61 and including upper end portions 62 A (not shown) and 62 B disposed at the approximate upper end of the blade 60 at opposing right and left ends thereof. The midway end portions 65 A and 65 B disposed at the approximate midway of the blade 60 at opposing right and left ends thereof. The blade 60 having a substantially rectangular configuration.
At the approximate midway of each of said arms 55 A and 55 B is disposed coupling joints 56 A and 56 B that attach to a pair of upper hydraulic cylinders 66 A and 66 B and a pair of lower hydraulic cylinders 67 A (not shown) and 67 B as will be further described.
Referring again to FIG. 3 , the frame 55 further including support plates 70 and 72 disposed between support arms 55 A and 55 B, the plates 70 and 72 provided to support the functional elements of the frame 55 .
The rear of the tractor 10 having pairs of upper and lower end joints 58 A (not shown), 58 B and 58 C (not shown), 58 D, respectively, for attaching the hydraulic cylinders 66 A, 66 B and 67 A and 67 B. Specifically, the upper hydraulic cylinders 66 A and 66 B are removably and pivotally installed to the upper end joints 58 A and 58 B of the rear of the tractor 10 ; and the lower hydraulic cylinders 67 A and 67 B are removably and pivotally installed to the lower end joints 58 C and 58 D of the rear of the tractor 10 . The other end of the pair of upper hydraulic cylinders 66 A and 66 B removably and pivotally attached to the upper end portions 62 A and 62 B of the inside of the blade 60 ; and the other end of the pair of lower hydraulic cylinders 67 A and 67 B removably and pivotally attached to the coupling joints 56 A and 56 B of the support arms 55 A and 55 B. The attachment are of a conventional manner known in the art.
As shown in the drawings, said upper hydraulic cylinders 66 A and 66 B being longer than the lower hydraulic cylinders 67 A and 67 B in order to further extend the blade 60 from the tractor 10 and to give sufficient clearance between the blade 60 and the tractor 10 . As should be obvious, as a result of the extended length of the upper hydraulic cylinders 66 A and 66 B, and as a result of said cylinders 66 A and 66 B being pivotally attached to the upper end portions 62 A and 62 B at the approximate upper end of the blade 60 , the blade 60 is able to be positioned higher than the standard forwardly mounted bucket 15 .
As should be appreciated from the description herein, the rear blade mounting structure 50 is symmetrically constructed with pairs of elements on opposite sides of the tractor 10 . As such, only the elements found on one side of the tractor 10 is primarily discussed and shown in the FIGS. 1–2 . It should be understood that the other set of elements are identical to those described, with the exception that the other set of elements are mirror images of the first set of elements described.
The application of the rear blade mounting structure 50 is generally operating means used for the conventional forwardly mounted bulldozer structure 12 known in the art.
In use, as shown in FIG. 2 , the blade 60 may be moved substantially vertically by rotating the frame 55 about pivot arm 57 B and the blade 60 can be rotated about pivot point 65 B which forms a substantial horizontal axis.
Starting with the blade 60 in the position in FIG. 1 , the user can retract upper cylinder pair 66 A, B to raise the blade 60 to the position shown in FIG. 2 . This position allows the user to position the blade 60 above a pile of material to be moved. Once in position the user can extend cylinder pair 67 A, B to drop the frame 55 and extend cylinder pair 66 A, B to achieve a third position shown in FIG. 5 . In this position, the blade edge 61 can dig in and by pulling the whole tractor 10 forward material in front of the blade 60 can be pulled forward.
With regard to rotation about a substantially horizontal axis, the user adjusts the blade 60 by selectively extending or retracting the upper hydraulic-cylinders 66 A and 66 B, and the lower hydraulic cylinders 67 A and 67 B. When said cylinders 66 A, 66 B and 67 A, 67 B are telescopically adjusted such to be shorter or longer, the blade 60 is shifted and rotates about said substantially horizontal axis.
If the user wishes the blade 60 to be oriented at a selected angle with respect to the longitudinal axis of the tractor 10 (as shown in FIGS. 1–2 ), the user extends either the upper hydraulic cylinders 66 A and 66 B or the lower hydraulic cylinders 67 A and 67 B until the blade 60 is at the desired orientation.
In the configuration of the present invention, the tractor 10 uses the forwardly mounted bulldozer bucket 15 to collect and remove earth, from a mine pit work site for example. When the bucket 15 cannot pivot so that the bucket 15 will collect the fine material at or near the walls of such pit generally on an ascending slope, the user utilizes the rear blade mounting structure 50 mounted to the rear of the tractor 10 to move such material so that the forwardly mounted bucket 15 is then able to collect and remove such material. Specifically, the operator raises the upper hydraulic cylinders 66 A and 66 B causing the blade 60 to rotate as shown in FIG. 2 , so that the blade 60 is positioned above the said material to be moved and on the approximate same vertical axis as the said wall of the pit. The operator then lowers the upper hydraulic cylinders 66 A and 66 B causing the blade edge member 61 of the blade 60 to lower and dig into the earth material as shown in FIG. 5 . Once the blade 60 is lowered to a selected depth, the operator then drags the material by driving the tractor 10 in the direction away from the wall of the pit while the blade 60 is dug into the material. As a result, the blade 60 moves that material in contact with the blade 60 , that material approximately between the blade 60 and the rear of the tractor 10 . It has been found that such material should be moved the approximate length of the body of the tractor 10 in order to make available to the bucket 15 for collection. Once moved, such material is then accessible to the bucket 15 and is collected and removed by the bucket 15 on the front of the tractor 10 in a conventional manner.
Although the description above contains many specificities, these should not be construed as limiting the scope of the invention but as merely providing illustrations of a presently preferred embodiment of this invention.
Though not shown, it would be possible to mount the upper cylinder pair 66 A, B with pivot point 55 B on the top edge of the frame 55 instead of on the tractor 10 . Such an arrangement would still allow the upper cylinder pair 66 A, B to pivot the blade 60 about pivot point 65 A, B to control the position of the blade 60 about the axis defined by pivot points 65 A, B.
Thus the scope of the invention should be determined by the appended claims in the formal application and their legal equivalents, rather than by the examples given.
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A rear blade mounting apparatus for a bulldozer. The mounting apparatus generally includes a frame that extends from the rear of the body of the bulldozer, the frame including a pair of extending loader arms pivotally connected to the rear of the tractor, and a blade pivotally mounted on free ends of the loader arms, and hydraulic cylinders, or the like, controlled to cause the blade to be positioned in various desired positions.
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RELATED APPLICATIONS
This is a Divisional of U.S. patent application Ser. No. 11/236,713 filed Sep. 28, 2005, which is a Continuation of International Application No. PCT/US2004/009994 filed Apr. 1, 2004, which claims the benefit of U.S. Provisional Patent Application No. 60/462,112 filed on Apr. 10, 2003 and U.S. Provisional Patent Application No. 60/485,033 filed on Jul. 2, 2003. The disclosures of these applications are incorporated herein by reference in their entireties.
BACKGROUND
Exposure apparatus are commonly used to transfer images from a reticle onto a semiconductor wafer during semiconductor processing. A typical exposure apparatus includes an illumination source, a reticle stage assembly that positions a reticle, an optical assembly, a wafer stage assembly that positions a semiconductor wafer, and a measurement system that precisely monitors the position of the reticle and the wafer.
Immersion lithography systems utilize a layer of immersion fluid that fills a gap between the optical assembly and the wafer. The wafer is moved rapidly in a typical lithography system and it would be expected to carry the immersion fluid away from the gap. This immersion fluid that escapes from the gap can interfere with the operation of other components of the lithography system. For example, the immersion fluid can interfere with the measurement system that monitors the position of the wafer.
SUMMARY
The invention is directed to an environmental system for controlling an environment in a gap between an optical assembly and a device that is retained by a device stage. The environmental system includes an immersion fluid source and a transport region that is positioned near the device. The immersion fluid source delivers an immersion fluid that enters the gap. The transport region captures immersion fluid that is exiting the gap. With this design, in certain embodiments, the invention avoids the use of direct vacuum suction on the device that could potentially distort the device and/or the optical assembly.
In one embodiment, the environmental system includes a fluid barrier that is positioned near the device and that encircles the gap. Furthermore, the fluid barrier can maintain the transport region near the device.
In one embodiment, the environmental system includes a fluid removal system that removes immersion fluid from near the transport region. In another embodiment, the fluid removal system can direct a removal fluid that removes immersion fluid from the transport region. In this embodiment, the removal fluid can be at a removal fluid temperature that is higher than an immersion fluid temperature of the immersion fluid.
In one embodiment, the transport region is a substrate that includes a plurality of passages for collecting the immersion fluid near the transport region. As an example, the transport region can be made of a material that conveys the immersion fluid by capillary action. In this embodiment, the passages can be a plurality of pores. In an alternative embodiment, the passages can be a plurality of spaced apart transport apertures that extend through the transport region.
The present invention also is directed to an exposure apparatus, a wafer, a device, a method for controlling an environment in a gap, a method for making an exposure apparatus, a method for making a device, and a method for manufacturing a wafer.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described in conjunction with exemplary embodiments in which like reference numerals designate like elements, and in which:
FIG. 1 is a side illustration of an exposure apparatus having features of the invention;
FIG. 2A is a perspective view of a portion of the exposure apparatus of FIG. 1 ;
FIG. 2B is a cut-away view taken on line 2 B- 2 B of FIG. 2A ;
FIG. 2C is an enlarged detailed view taken on line 2 C- 2 C in FIG. 2B ;
FIG. 2D is an enlarged detailed view of another embodiment of a portion of an exposure apparatus;
FIG. 3A is a side illustration: of an immersion fluid source having features of the invention;
FIG. 3B is a side illustration of a fluid removal system having features of the invention;
FIG. 3C is a side illustration of another embodiment of a fluid removal system having features of the invention;
FIG. 3D is a side illustration of another embodiment of a fluid removal system having features of the invention;
FIG. 4 is an enlarged cut-away view of a portion of another embodiment of an exposure apparatus;
FIG. 5A is an enlarged cut-away view of a portion of another embodiment of an exposure apparatus;
FIG. 5B is an enlarged detailed view taken on line 5 B- 5 B in FIG. 5A ;
FIG. 6A is a flow chart that outlines a process for manufacturing a device in accordance with the invention; and
FIG. 6B is a flow chart that outlines device processing in more detail.
DETAILED DESCRIPTION OF EMBODIMENTS
FIG. 1 is a schematic illustration of a precision assembly, namely an exposure apparatus 10 having features of the invention. The exposure apparatus 10 includes an apparatus frame 12 , an illumination system 14 (irradiation apparatus), an optical assembly 16 , a reticle stage assembly 18 , a device stage assembly 20 , a measurement system 22 , a control system 24 , and a fluid environmental system 26 . The design of the components of the exposure apparatus 10 can be varied to suit the design requirements of the exposure apparatus 10 .
A number of Figures include an orientation system that illustrates an X axis, a Y axis that is orthogonal to the X axis, and a Z axis that is orthogonal to the X and Y axes. It should be noted that these axes also can be referred to as the first, second and third axes.
The exposure apparatus 10 is particularly useful as a lithographic device that transfers a pattern (not shown) of an integrated circuit from a reticle 28 onto a semiconductor wafer 30 (illustrated in phantom). The wafer 30 is also referred to generally as a device, or work piece. The exposure apparatus 10 mounts to a mounting base 32 , e.g., the ground, a base, or floor or some other supporting structure.
There are a number of different types of lithographic devices. For example, the exposure apparatus 10 can be used as a scanning type photolithography system that exposes the pattern from the reticle 28 onto the wafer 30 with the reticle 28 and the wafer 30 moving synchronously. In a scanning type lithographic apparatus, the reticle 28 is moved perpendicularly to an optical axis of the optical assembly 16 by the reticle stage assembly 18 and the wafer 30 is moved perpendicularly to the optical axis of the optical assembly 16 by the wafer stage assembly 20 . Irradiation of the reticle 28 and exposure of the wafer 30 occur while the reticle 28 and the wafer 30 are moving synchronously.
Alternatively, the exposure apparatus 10 can be a step-and-repeat type photolithography system that exposes the reticle 28 while the reticle 28 and the wafer 30 are stationary. In the step and repeat process, the wafer 30 is in a constant position relative to the reticle 28 and the optical assembly 16 during the exposure of an individual field. Subsequently, between consecutive exposure steps, the wafer 30 is consecutively moved with the wafer stage assembly 20 perpendicularly to the optical axis of the optical assembly 16 so that the next field of the wafer 30 is brought into position relative to the optical assembly 16 and the reticle 28 for exposure. Following this process, the images on the reticle 28 are sequentially exposed onto the fields of the wafer 30 , and then the next field of the wafer 30 is brought into position relative to the optical assembly 16 and the reticle 28 .
However, the use of the exposure apparatus 10 provided herein is not limited to a photolithography system for semiconductor manufacturing. The exposure apparatus 10 , for example, can be used as an LCD photolithography system that exposes a liquid crystal display device pattern onto a rectangular glass plate or a photolithography system for manufacturing a thin film magnetic head.
The apparatus frame 12 supports the components of the exposure apparatus 10 . The apparatus frame 12 illustrated in FIG. 1 supports the reticle stage assembly 18 , the wafer stage assembly 20 , the optical assembly 16 and the illumination system 14 above the mounting base 32 .
The illumination system 14 includes an illumination source 34 and an illumination optical assembly 36 . The illumination source 34 emits a beam (irradiation) of light energy. The illumination optical assembly 36 guides the beam of light energy from the illumination source 34 to the optical assembly 16 . The beam illuminates selectively different portions of the reticle 28 and exposes the wafer 30 . In FIG. 1 , the illumination source 34 is illustrated as being supported above the reticle stage assembly 18 . Typically, however, the illumination source 34 is secured to one of the sides of the apparatus frame 12 and the energy beam from the illumination source 34 is directed to above the reticle stage assembly 18 with the illumination optical assembly 36 .
The illumination source 34 can be a g-line source (436 nm), an i-line source (365 nm), a KrF excimer laser (248 nm), an ArF excimer laser (193 nm) or a F 2 laser (157 nm). Alternatively, the illumination source 34 can generate charged particle beams such as an x-ray or an electron beam. For instance, in the case where an electron beam is used, thermionic emission type lanthanum hexaboride (LaB 6 ) or tantalum (Ta) can be used as a cathode for an electron gun. Furthermore, in the case where an electron beam is used, the structure could be such that either a mask is used or a pattern can be directly formed on a substrate without the use of a mask.
The optical assembly 16 projects and/or focuses the light passing through the reticle 28 to the wafer 30 . Depending upon the design of the exposure apparatus 10 , the optical assembly 16 can magnify or reduce the image illuminated on the reticle 28 . The optical assembly 16 need not be limited to a reduction system. It also could be a 1× or magnification system.
When far ultra-violet rays such as the excimer laser is used, glass materials such as quartz and fluorite that transmit far ultra-violet rays can be used in the optical assembly 16 . When the F 2 type laser or x-ray is used, the optical assembly 16 can be either catadioptric or refractive (a reticle should also preferably be a reflective type), and when an electron beam is used, electron optics can consist of electron lenses and deflectors. The optical path for the electron beams should be in a vacuum.
Also, with an exposure device that employs vacuum ultra-violet radiation (VUV) of wavelength 200 nm or lower, use of the catadioptric type optical system can be considered. Examples of the catadioptric type of optical system include Japanese Laid-Open Patent Application Publication No. 8-171054 and its counterpart U.S. Pat. No. 5,668,672, as well as Japanese Laid-Open Patent Application Publication No. 10-20195 and its counterpart U.S. Pat. No. 5,835,275. In these cases, the reflecting optical device can be a catadioptric optical system incorporating a beam splitter and concave mirror. Japanese Laid-Open Patent Application Publication No. 8-334695 and its counterpart U.S. Pat. No. 5,689,377 as well as Japanese Laid-Open Patent Application Publication No. 10-3039 and its counterpart U.S. Pat. Application No. 873,605 (Application Date: Jun. 12, 1997) also use a reflecting-refracting type of optical system incorporating a concave mirror, etc., but without a beam splitter, and can also be employed with this invention. The disclosures of the above-mentioned U.S. patents and Japanese Laid-Open patent applications publications are incorporated herein by reference in their entireties.
In one embodiment, the optical assembly 16 is secured to the apparatus frame 12 with one or more optical mount isolators 37 . The optical mount isolators 37 inhibit vibration of the apparatus frame 12 from causing vibration to the optical assembly 16 . Each optical mount isolator 37 can include a pneumatic cylinder (not shown) that isolates vibration and an actuator (not shown) that isolates vibration and controls the position with at least two degrees of motion. Suitable optical mount isolators 37 are sold by Integrated Dynamics Engineering, located in Woburn, Mass. For ease of illustration, two spaced apart optical mount isolators 37 are shown as being used to secure the optical assembly 16 to the apparatus frame 12 . However, for example, three spaced apart optical mount isolators 37 can be used to kinematically secure the optical assembly 16 to the apparatus frame 12 .
The reticle stage assembly 18 holds and positions the reticle 28 relative to the optical assembly 16 and the wafer 30 . In one embodiment, the reticle stage assembly 18 includes a reticle stage 38 that retains the reticle 28 and a reticle stage mover assembly 40 that moves and positions the reticle stage 38 and reticle 28 .
Somewhat similarly, the device stage assembly 20 holds and positions the wafer 30 with respect to the projected image of the illuminated portions of the reticle 28 . In one embodiment, the device stage assembly 20 includes a device stage 42 that retains the wafer 30 , a device stage base 43 that supports and guides the device stage 42 , and a device stage mover assembly 44 that moves and positions the device stage 42 and the wafer 30 relative to the optical assembly 16 and the device stage base 43 . The device stage 42 is described in more detail below.
Each stage mover assembly 40 , 44 can move the respective stage 38 , 42 with three degrees of freedom, less than three degrees of freedom, or more than three degrees of freedom. For example, in alternative embodiments, each stage mover assembly 40 , 44 can move the respective stage 38 , 42 with one, two, three, four, five or six degrees of freedom. The reticle stage mover assembly 40 and the device stage mover assembly 44 can each include one or more movers, such as rotary motors, voice coil motors, linear motors utilizing a Lorentz force to generate drive force, electromagnetic movers, planar motors, or other force movers.
In photolithography systems, when linear motors (see U.S. Pat. Nos. 5,623,853 or 5,528,118) are used in the wafer stage assembly or the reticle stage assembly, the linear motors can be either an air levitation type employing air bearings or a magnetic levitation type using Lorentz force or reactance force. Additionally, the stage could move along a guide, or it could be a guideless type stage that uses no guide. The disclosures of U.S. Pat. Nos. 5,623,853 and 5,528,118 are incorporated herein by reference in their entireties.
Alternatively, one of the stages could be driven by a planar motor that drives the stage by an electromagnetic force generated by a magnet unit having two-dimensionally arranged magnets and an armature coil unit having two-dimensionally arranged coils in facing positions. With this type of driving system, either the magnet unit or the armature coil unit is connected to the stage base and the other unit is mounted on the moving plane side of the stage.
Movement of the stages as described above generates reaction forces that can affect performance of the photolithography system. Reaction forces generated by the wafer (substrate) stage motion can be mechanically transferred to the floor (ground) by use of a frame member as described in U.S. Pat. No. 5,528,100 and Japanese Laid-Open Patent Application Publication No. 8-136475. Additionally, reaction forces generated by the reticle (mask) stage motion can be mechanically transferred to the floor (ground) by use of a frame member as described in U.S. Pat. No. 5,874,820 and Japanese Laid-Open Patent Application Publication No. 8-330224. The disclosures of U.S. Pat. Nos. 5,528,100 and 5,874,820 and Japanese Laid-Open Patent Application Publication Nos. 8-136475 and 8-330224 are incorporated herein by reference in their entireties.
The measurement system 22 monitors movement of the reticle 28 and the wafer 30 relative to the optical assembly 16 or some other reference. With this information, the control system 24 can control the reticle stage assembly 18 to precisely position the reticle 28 and the device stage assembly 20 to precisely position the wafer 30 . The design of the measurement system 22 can vary. For example, the measurement system 22 can utilize multiple laser interferometers, encoders, mirrors, and/or other measuring devices.
The control system 24 receives information from the measurement system 22 and controls the stage mover assemblies 40 , 44 to precisely position the reticle 28 and the wafer 30 . Additionally, the control system 24 can control the operation of the components of the environmental system 26 . The control system 24 can include one or more processors and circuits.
The environmental system 26 controls the environment in a gap 246 (illustrated in FIG. 2B ) between the optical assembly 16 and the wafer 30 . The gap 246 includes an imaging field. The imaging field includes the area adjacent to the region of the wafer 30 that is being exposed and the area in which the beam of light energy travels between the optical assembly 16 and the wafer 30 . With this design, the environmental system 26 can control the environment in the imaging field.
The desired environment created and/or controlled in the gap 246 by the environmental system 26 can vary accordingly to the wafer 30 and the design of the rest of the components of the exposure apparatus 10 , including the illumination system 14 . For example, the desired controlled environment can be a fluid such as water. Alternatively, the desired controlled environment can be another type of fluid.
FIG. 2A is a perspective view of the wafer 30 , and a portion of the exposure apparatus 10 of FIG. 1 including the optical assembly 16 , the device stage 42 , and the environmental system 26 .
FIG. 2B is a cut-away view of the portion of the exposure apparatus 10 of FIG. 2A , including the optical assembly 16 , the device stage 42 , and the environmental system 26 . FIG. 2B illustrates that the optical assembly 16 includes an optical housing 250 A, a last optical element 250 B, and an element retainer 250 C that secures the last optical element 250 B to the optical housing 250 A. Additionally, FIG. 2B illustrates the gap 246 between the last optical element 250 B and the wafer 30 . In one embodiment, the gap 246 is approximately 1 mm.
In one embodiment, the environmental system 26 fills the imaging field and the rest of the gap 246 with an immersion fluid 248 (illustrated as circles). The design of the environmental system 26 and the components of the environmental system 26 can be varied. In the embodiment illustrated in FIG. 2B , the environmental system 26 includes an immersion fluid system 252 , a fluid barrier 254 , and a transport region 256 . In this embodiment, (i) the immersion fluid system 252 delivers and/or injects the immersion fluid 248 into the gap 246 , removes the immersion fluid 248 from or near the transport region 256 , and/or facilitates the movement of the immersion fluid 248 through the transport region 256 , (ii) the fluid barrier 254 inhibits the flow of the immersion fluid 248 away from near the gap 246 , and (iii) the transport region 256 transfers and/or conveys the immersion fluid 248 flowing from the gap 246 . The fluid barrier 254 also forms a chamber 257 near the gap 246 .
The design of the immersion fluid system 252 can vary. For example, the immersion fluid system 252 can inject the immersion fluid 248 at one or more locations at or near the gap 246 and chamber 257 , the edge of the optical assembly 16 , and/or directly between the optical assembly 16 and the wafer 30 . Further, the immersion fluid system 252 can assist in removing and/or scavenging the immersion fluid 248 at one or more locations at or near the device 30 , the gap 246 and/or the edge of the optical assembly 16 .
In the embodiment illustrated in FIG. 2B , the immersion fluid system 252 includes one or more injector nozzles 258 (only one is illustrated) positioned near the perimeter of the optical assembly 16 and an immersion fluid source 260 . FIG. 2C illustrates one injector nozzle 258 in more detail. In this embodiment, each of the injector nozzles 258 includes a nozzle outlet 262 that is in fluid communication with the immersion fluid source 260 . At the appropriate time, the immersion fluid source 260 provides immersion fluid 248 to the one or more nozzle outlets 262 that is released into the chamber 257 .
FIGS. 2B and 2C also illustrate that the immersion fluid 248 in the chamber 257 sits on top of the wafer 30 . The immersion fluid 248 flows into the gap 246 . Further, as the wafer 30 moves under the optical assembly 16 , it will drag the immersion fluid 248 in the vicinity of the top surface of the wafer 30 with the wafer 30 into the gap 246 .
In one embodiment, the fluid barrier 254 forms the chamber 257 around the gap 246 , restricts the flow of the immersion fluid 248 from the gap 246 , assists in maintaining the gap 246 full of the immersion fluid 248 , and facilitates the recovery of the immersion fluid 248 that escapes from the gap 246 . In one embodiment, the fluid barrier 254 encircles and is positioned entirely around the gap 246 and the bottom of the optical assembly 16 . Further, in one embodiment, the fluid barrier 254 confines the immersion fluid 248 to a region on the wafer 30 and the device stage 42 centered on the optical assembly 16 . Alternatively, for example, the fluid barrier 254 can be positioned around only a portion of the gap 246 or the fluid barrier 254 can be off-center of the optical assembly 16 .
In the embodiment illustrated in FIGS. 2B and 2C , the fluid barrier 254 includes a containment frame 264 , and a frame support 268 . In this embodiment, the containment frame 264 is generally annular ring shaped and encircles the gap 246 . Additionally, in this embodiment, the containment frame 264 includes a top side 270 A, an opposed bottom side 270 B that faces the wafer 30 , an inner side 270 C that faces the gap 246 , and an outer side 270 D. Moreover, in this embodiment, the fluid barrier 254 includes a channel 272 for receiving the transport region 256 . As an example, the channel 272 can be annular shaped.
The terms top and bottom are used merely for convenience, and the orientation of the containment frame 264 can be rotated. It should also be noted that the containment frame 264 can have another shape. For example, the containment frame 264 can be rectangular frame shaped, octagonal frame shaped, oval frame shaped, or another suitable shape.
The frame support 268 connects and supports the containment frame 264 to the apparatus frame 12 , another structure, and/or the optical assembly 16 , above the wafer 30 and the device stage 42 . In one embodiment, the frame support 268 supports all of the weight of the containment frame 264 . Alternatively, for example, the frame support 268 can support only a portion of the weight of the containment frame 264 . In one embodiment, the frame support 268 can include one or more support assemblies 274 . For example, the frame support 268 can include three spaced apart support assemblies 274 (only two are illustrated in FIG. 2B ). In this embodiment, each support assembly 274 extends between the optical assembly 16 and the inner side 270 C of the containment frame 264 .
In one embodiment, each support assembly 274 is a mount that rigidly secures the containment frame 264 to the optical assembly 16 . Alternatively, for example, each support assembly can be a flexure that supports the containment frame 264 in a flexible fashion. As used herein, the term “flexure” shall mean a part that has relatively high stiffness. in some directions and relatively low stiffness in other directions. In one embodiment, the flexures cooperate (i) to be relatively stiff along the X axis and along the Y axis, and (ii) to be relatively flexible along the Z axis. In this embodiment, the flexures can allow for motion of the containment frame 264 along the Z axis and inhibit motion of the containment frame 264 along the X axis and the Y axis.
Alternatively, for example, each support assembly 274 can be an actuator that can be used to adjust the position of the containment frame 264 relative to the wafer 30 and the device stage 42 . In this embodiment, the frame support 268 can also include a frame measurement system (not shown) that monitors the position of the containment frame 264 . For example, the frame measurement system can monitor the position of the containment frame 264 along the Z axis, about the X axis, and/or about the Y axis. With this information, the support assemblies 274 can be used to adjust the position of the containment frame 264 . In this embodiment, the support assemblies 274 can actively adjust the position of the containment frame 264 .
FIGS. 2B and 2C also illustrate the transport region 256 in more detail. In this embodiment, the transport region 256 is a substrate 275 that is substantially annular disk shaped, encircles the gap 246 , and is substantially concentric with the optical assembly 16 . Alternatively, for example, the substrate 275 can be another shape, including oval frame shaped, rectangular frame shaped or octagonal frame shaped. Still alternatively, for example, the transport region 256 can include a plurality of substrate segments that cooperate to encircle a portion of the gap 246 , and/or a plurality of substantially concentric substrates.
The dimensions of the transport region 256 can be selected to achieve the desired immersion fluid recovery rate.
Further, in this embodiment, the transport region 256 is secured to the containment frame 264 at or near the bottom side 270 B of the containment frame 264 and cooperates with the containment frame 264 to form a removal chamber 276 next to and above the transport region 256 . Moreover, as illustrated in FIG. 2C , the transport region 256 includes a first surface 278 A that is adjacent to the removal chamber 276 and an opposite second surface 278 B that is adjacent to the device 30 and the gap 246 .
In this embodiment, the transport region 256 captures, retains, and/or absorbs at least a portion of the immersion fluid 248 that flows between the containment frame 264 and the wafer 30 and/or the device stage 42 . The type of material utilized in the transport region 256 can vary. In one embodiment, the substrate 275 includes a plurality of passages 280 . For example, the passages 280 can be relatively small and tightly packed.
As an example, the transport region 256 can be a porous material having a plurality of pores and/or interstices that convey the immersion fluid 248 by capillary action. In this embodiment, the passages 280 can be small enough so that capillary forces draw the immersion fluid 248 into the pores. Examples of suitable materials include wick type structures made of metals, glasses, or ceramics'. Examples of suitable wick type structures include any material with a network of interconnected, small passages, including, but not limited to, woven fiberglass, sintered metal powders, screens, wire meshes, or grooves in any material. The transport region 256 can be hydrophilic.
In one embodiment, the transport region 256 has a pore size of between approximately 20 and 200 microns. In alternative embodiments, the transport region 256 can have a porosity of at least approximately 40, 80, 100, 140, 160 or 180.
In certain embodiments, a relatively higher flow capacity is required. To accommodate higher flow, larger porosity material may be necessary for the transport region 256 . The choice for the porosity of the transport region 256 depends on the overall flow rate requirement of the transport region 256 . Larger overall flow rates can be achieved by using a transport region 256 having a larger porosity, decreasing the thickness of the transport region 256 , or increasing the surface area of the transport region 256 . In one embodiment, with a flow rate requirement of 0.3-1.0 L/min in immersion lithography, pores size of 40-150 μm can be used to cover a 30-150 cm 2 area for immersion fluid 248 recovery. The type and specifications of the porous material also depends on the application and the properties of the immersion fluid 248 .
Referring back to FIG. 2B , in certain embodiments, the transport region 256 has a limited capacity to absorb the immersion fluid 248 . In one embodiment, the immersion fluid system 252 includes a fluid removal system 282 that removes immersion fluid 248 from or near the transport region 256 and that is in fluid communication with the transport region 256 and the removal chamber 276 . With this design, the immersion fluid 248 can be captured with the transport region 256 and removed by the fluid removal system 276 .
In one embodiment, the fluid removal system 282 removes the immersion fluid 248 from the top first surface 278 A of the transport region 256 allowing additional immersion fluid 248 to flow into the bottom, second surface 278 B of the transport region 256 . For example, the fluid removal system 282 can create a pressure differential across the transport region 256 . In one example, the fluid removal system 282 causes the pressure at the first surface 278 A to be lower than the pressure at the second surface 278 B.
The removal of the immersion fluid 248 can be accomplished in several different ways and a number of embodiments of the fluid removal system 282 are described below.
FIG. 2C illustrates that a frame gap 284 exists between (i) the bottom side 270 B of the containment frame 264 and the second surface 278 B of the transport region 256 , and (ii) the wafer 30 and/or the device stage 42 to allow for ease of movement of the device stage 42 and the wafer 30 relative to the containment frame 264 . The size of the frame gap 284 can vary. In one embodiment, the frame gap 284 is between approximately 0.1 and 2 mm. In alternative examples, the frame gap 284 can be approximately 0.05, 0.1, 0.2, 0.5, 1, 1.5, 2, 3, or 5 mm.
With this embodiment, most of the immersion fluid 248 is confined within the fluid barrier 254 and most of the leakage around the periphery is scavenged within the narrow frame gap 284 by the transport region 256 . In this case, when the immersion fluid 248 touches the transport region 256 , it is drawn into the transport region 256 and absorbed. Thus, the transport region 256 inhibits any immersion fluid 248 from flowing outside the ring.
FIG. 2D illustrates a cut-away view of a portion of another embodiment of an exposure apparatus 10 D that is somewhat similar to the embodiment illustrated in FIG. 2C . However, in FIG. 2D , the device 30 D and/or the stage 42 D is closer to the bottom side 270 BD of the inner side 270 CD and/or the outer side 270 DD of the containment frame 264 D than the second surface 278 DB of the transport region 256 D. Stated another way, the distance between the bottom side 270 BD and the device 30 D and/or the stage 42 D is less than the distance between the second surface 278 DB and the device 30 D and/or the stage 42 D.
FIG. 3A illustrates one embodiment of the immersion fluid source 260 . In this embodiment, the immersion fluid source 260 includes (i) a fluid reservoir 386 A that retains the immersion fluid 248 , (ii) a filter 386 B in fluid communication with the fluid reservoir 386 A that filters the immersion fluid 248 , (iii) a de-aerator 386 C in fluid communication with the filter 386 B that removes any air, contaminants, or gas from the immersion fluid 248 , (iv) a temperature controller 386 D, e.g., a heat exchanger or chiller, in fluid communication with the de-aerator 386 C that controls the temperature of the immersion fluid 248 , (v) a pressure source 386 E, e.g., a pump, in fluid communication with the temperature controller 386 D, and (vi) a flow controller 386 F that has an inlet in fluid communication with the pressure source 386 E and an outlet in fluid communication with the nozzle outlets 262 (illustrated in FIG. 2C ), the flow controller 386 F controlling the pressure and flow to the nozzle outlets 262 .
Additionally, the immersion fluid source 260 can include (i) a pressure sensor 386 G that measures the pressure of the immersion fluid 248 that is delivered to the nozzle outlets 262 , (ii) a flow sensor 386 H that measures the rate of flow of the immersion fluid 248 to the nozzle outlets 262 , and (iii) a temperature sensor 386 I that measures the temperature of the immersion fluid 248 to the nozzle outlets 262 . The operation of these components can be controlled by the control system 24 (illustrated in FIG. 1 ) to control the flow rate, temperature and/or pressure of the immersion fluid 248 to the nozzle outlets 262 . The information from these sensors 386 G- 386 I can be transferred to the control system 24 so that the control system 24 can appropriately adjust the other components of the immersion fluid source 260 to achieve the desired temperature, flow and/or pressure of the immersion fluid 248 .
The orientation of the components of the immersion fluid source 260 can be varied. Further, one or more of the components may not be necessary and/or some of the components can be duplicated. For example, the immersion fluid source 260 can include multiple pumps, multiple reservoirs, temperature controllers or other components. Moreover, the environmental system 26 can include multiple immersion fluid sources 260 .
The rate at which the immersion fluid 248 is pumped into the gap 246 (illustrated in FIG. 2B ) can vary. In one embodiment, the immersion fluid 248 is supplied to the gap 246 via the nozzle outlets 262 at a rate of between approximately 0.5 liters/min to 2 liters/min. However, the rate can be greater or less than these amounts.
The type of immersion fluid 248 can be varied to suit the design requirements of the apparatus 10 . In one embodiment, the immersion fluid 248 is a fluid such as de-gassed, de-ionized water. Alternatively, for example, the immersion fluid 248 can be another type of fluid, such as a per-fluorinated polyether (PFPE) such as Fomblin oil.
FIG. 3B illustrates a first embodiment of the fluid removal system 382 B and an illustration of a portion of the fluid barrier 254 , the transport region 256 , the wafer 30 , and the immersion fluid 248 . The fluid removal system 382 B is also referred to herein as a pressure system. In one embodiment, the fluid removal system 382 B creates and/or applies a transport pressure to the first surface 278 A of the transport region 256 . In this embodiment, the fluid removal system 382 B maintains the transport pressure at the first surface 278 A of the transport region 256 so that a pressure differential exists between the first surface 278 A and the second surface 278 B. In alternative embodiments, the fluid removal system 382 B controls the pressure in the removal chamber 276 so that the transport pressure at the first surface 278 A is approximately −10, −100, −500, −1000, −2000, −5000, −7000 or −10,000 Pa gage.
In FIG. 3B , the fluid removal system 382 B includes (i) a low pressure source 390 BA that creates a low chamber pressure in the removal chamber 276 , and (ii) a recovery reservoir 390 BC that captures immersion fluid 248 from the removal chamber 276 . In this embodiment, the low pressure source 390 BA can include a pump or vacuum source 390 BD, and a chamber pressure regulator 390 BE for precisely controlling the chamber pressure in the chamber 276 . In alternative embodiments, for example, the chamber pressure is controlled to be approximately −10, −100, −500, −1000, −2000, −5000, −7000 or −10,000 Pa gage. The chamber pressure regulator 390 BE can be controlled by the control system 24 to control the chamber pressure.
FIG. 3C illustrates another embodiment of the fluid removal system 382 C and an illustration of a portion of the fluid barrier 254 , the transport region 256 , the wafer 30 , and the immersion fluid 248 . In this embodiment, the fluid removal system 382 C forces a dry removal fluid 396 (illustrated as triangles), e.g., air through the removal chamber 276 and across the top first surface 278 A of the transport region 256 . The removal fluid 396 will dry the top surface 278 A of the transport region 256 , pumping immersion fluid 248 out of the transport region 256 . The removal fluid 396 can be heated in some cases, improving the flow of the immersion fluid 248 into the dry removal fluid 396 . Stated another way, in one embodiment, the removal fluid 396 is at a removal fluid temperature that is higher than an immersion fluid temperature of the immersion fluid 248 .
In FIG. 3C , the fluid removal system 382 C includes (i) a fluid source 396 A of the pressurized drying removal fluid 396 , (ii) a temperature controller 396 B that controls the temperature of the drying removal fluid 396 , (iii) a flow sensor 396 C that measures the flow of the drying removal fluid 396 , and (iv) a temperature sensor 396 D that measures the temperature of the drying removal fluid 396 . The fluid source 396 A can include a pump controlled by the control system 24 , and the temperature controller 396 B can be a heater that is controlled by the control system 24 .
FIG. 3D illustrates yet another embodiment of the fluid removal system 382 D and an illustration of a portion of the fluid barrier 254 , the transport region 256 , the wafer 30 , and the immersion fluid 248 . In this embodiment, the transport region 256 is extended outside the fluid barrier 254 . Further, the fluid removal system 382 C includes a heat source 397 that directs a heated fluid 396 F (illustrated as triangles) at the first surface 278 A of the transport region 256 , causing the immersion fluid 248 to boil out of the transport region 256 and be captured.
The orientation of the components of the fluid removal systems 382 B- 382 D illustrated in FIGS. 3B-3D can be varied. Further, one or more of the components may not be necessary and/or some of the components can be duplicated. For example, each of the fluid removal systems 382 B, 382 C, 382 D can include multiple pumps, multiple reservoirs, valves, or other components. Moreover, the environmental system 26 can include multiple fluid removal systems 382 B, 382 C, 382 D.
FIG. 4 is an enlarged view of a portion of another embodiment of the environmental system 426 , a portion of the wafer 30 , and a portion of the device stage 42 . In this embodiment, the environmental system 426 is somewhat similar to the corresponding component described above and illustrated in FIGS. 2A-2C . However, in this embodiment, the transport region 456 is slightly different. In particular, in this embodiment, the passages 480 (only two are illustrated) in the substrate 475 of the transport region 456 are a plurality of spaced apart transport apertures that extend substantially transversely through the substrate 475 between the first surface 478 A and the second surface 478 B.
In this embodiment, for example, the substrate 475 can be made of a material such as glass or other hydrophilic materials. In one embodiment, the transport apertures 480 can have a diameter of between approximately 0.1 and 0.2 mm. However, in certain embodiments, the transport apertures can be larger or smaller than these amounts.
With this design, for example, one or more of the fluid removal systems 382 B, 382 C (illustrated in FIGS. 3B and 3C ) can be used to apply a vacuum or partial vacuum on the transport apertures 480 . The partial vacuum draws the immersion fluid 248 through the transport region 456 .
FIG. 5A is a cut-away view of a portion of another embodiment of the exposure apparatus 510 , including the optical assembly 516 , the device stage 542 , and the environmental system 526 . FIG. 5A also illustrates the wafer 30 , the gap 546 , and that the immersion fluid 548 fills the gap 546 . FIG. 5B illustrates an enlarged portion of FIG. 5A taken on line 5 B- 5 B.
In this embodiment, the environmental system 526 again includes an immersion fluid system 552 , a fluid barrier 554 , and a transport region 556 that are somewhat similar to the corresponding components described above. In this embodiment, the fluid barrier 554 includes a containment frame 564 that forms a chamber 557 around the gap 546 , and a frame support 568 that connects and supports the containment frame 564 to the apparatus frame 12 . However, in this embodiment, the containment frame 564 includes (i) an annular shaped first channel 581 that defines a nozzle outlet 562 that is in fluid communication with an immersion fluid source 560 of the immersion fluid system 552 ; (ii) an annular shaped second channel 583 , (iii) an annular shaped third channel 585 , and (iv) an annular shaped fourth channel 587 for receiving the transport region 556 . In this embodiment, the channels 581 , 583 , 585 , 587 are approximately concentric and are centered about the optical assembly 516 . Further, in this embodiment, the second channel 583 encircles the first channel 581 , the third channel 585 encircles the second channel 583 , and the fourth channel 587 encircles the third channel 585 . However, the shape, orientation, and/or position of the channels 581 , 583 , 585 , 587 can be changed.
In one embodiment, the immersion fluid system 552 provides the immersion fluid 548 to the first channel 581 and the nozzle outlet 562 that is released into the chamber 557 . The transport region 556 cooperates with the containment frame 564 to form a removal chamber 576 next to and above the transport region 556 . Moreover, the transport region 556 includes a first surface 578 A that is adjacent to the removal chamber 576 and an opposite second surface 578 B that is adjacent to the device 30 and the gap 546 .
In this embodiment, the third channel 585 is in fluid communication with a first removal system 528 A. In one embodiment, the first removal system 528 A creates a vacuum or partial vacuum in the third channel 585 that pulls and/or draws the immersion fluid 548 into the third channel 585 . For example, in alternative embodiments, the first removal system 528 A can maintain the pressure in the third channel 585 at approximately −10, −100, −500, −1000, −2000, −5000, −7000 or −10,000 Pa gage.
Further, in this embodiment, the fourth channel 587 is in fluid communication with a second removal system 528 B. In this embodiment, the second removal system 528 B removes the immersion fluid 548 from the top first surface 578 A of the transport region 556 , allowing additional immersion fluid 548 to flow into the bottom, second surface 578 B of the transport region 556 .
In one embodiment, the design of the first removal system 528 A can be somewhat similar to the design of one of the removal systems 382 B, 382 C illustrated in FIGS. 3B-3D and/or the design of the second removal system 528 B can be somewhat similar to one of the designs illustrated in FIGS. 3B-3D .
In one embodiment, the majority of the immersion fluid 548 exiting from the gap 546 is recovered through the third channel 585 . For example, the third channel 585 can recover between approximately 80-90 percent of the immersion fluid 548 recovered from the gap 546 . In alternative embodiments, the third channel 585 can recover at least approximately 50, 60, 70, 80, or 90 percent of the immersion fluid 548 recovered from the gap 546 . With this design, the fourth channel 587 can be used to capture the immersion fluid 548 not captured by the third channel 585 .
Additionally, in one embodiment, the environmental system 526 includes a pressure controller 591 that can be used to control the pressure in the gap 546 . In one embodiment, the pressure controller 591 can cause the pressure in the gap 546 to be approximately equal to the pressure outside of the gap 546 . For example, in one embodiment, the second channel 583 defines the pressure controller 591 . In this embodiment, the second channel 583 is open to the atmospheric pressure and is positioned inside the periphery of third channel 585 . With this design, the negative pressure (vacuum or partial vacuum) in the third channel 585 will not strongly influence the pressure between the optical assembly 516 and the wafer 30 .
Alternatively, for example, a control pressure source 593 can deliver a control fluid 595 (illustrated as triangles) to the second channel 583 that is released into the gap 546 . In one embodiment, the control fluid 595 can be a gas that is not easily absorbed by the immersion fluid 548 . For example, if the immersion fluid 548 is water, the control fluid 595 can be water. If the immersion fluid 548 does not absorb the control fluid 595 or otherwise react to it, the chances of bubble formation on the surface of the wafer 30 can be reduced.
In yet another embodiment, the environmental system 526 can include a device for creating a fluid bearing (not shown) between the containment frame 564 and the wafer 30 and/or the device stage 542 . For example, the containment frame 564 can include one or more bearing outlets (not shown) that are in fluid communication with a bearing fluid source (not shown) of a bearing fluid (not shown). In this embodiment, the bearing fluid source provides pressurized fluid to the bearing outlet to create the aerostatic bearing. The fluid bearings can support all or a portion of the weight of the containment frame 564 .
It should be noted that in each embodiment, additional transport regions can be added as necessary.
Semiconductor devices can be fabricated using the above described systems, by the process shown generally in FIG. 6A . In step 601 the device's function and performance characteristics are designed. Next, in step 602 , a mask (reticle) having a pattern is designed according to the previous designing step, and in a parallel step 603 a wafer is made from a silicon material. The mask pattern designed in step 602 is exposed onto the wafer from step 603 in step 604 by a photolithography system described hereinabove in accordance with the invention. In step 605 the semiconductor device is assembled (including the dicing process, bonding process and packaging process). Finally, the device is then inspected in step 606 .
FIG. 6B illustrates a detailed flowchart example of the above-mentioned step 604 in the case of fabricating semiconductor devices. In FIG. 6B , in step 611 (oxidation step), the wafer surface is oxidized. In step 612 (CVD step), an insulation film is formed on the wafer surface. In step 613 (electrode formation step), electrodes are formed on the wafer by vapor deposition. In step 614 (ion implantation step), ions are implanted in the wafer. The above mentioned steps 611 - 614 form the preprocessing steps for wafers during wafer processing, and selection is made at each step according to processing requirements.
At each stage of wafer processing, when the above-mentioned preprocessing steps have been completed, the following post-processing steps are implemented. During post-processing, first, in step 615 (photoresist formation step), photoresist is applied to a wafer. Next, in step 616 (exposure step), the above-mentioned exposure device is used to transfer the circuit pattern of a mask (reticle) to a wafer. Then in step 617 (developing step), the exposed wafer is developed, and in step 618 (etching step), parts other than residual photoresist (exposed material surface) are removed by etching. In step 619 (photoresist removal step), unnecessary photoresist remaining after etching is removed.
Multiple circuit patterns are formed by repetition of these preprocessing and post-processing steps.
While the particular exposure apparatus 10 as shown and described herein is fully capable of obtaining the objects and providing the advantages previously stated, it is to be understood that it is merely illustrative of embodiments of the invention. No limitations are intended to the details of construction or design herein shown.
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A lithographic projection apparatus that is arranged to project a pattern from a patterning device onto a substrate using a projection system has a liquid supply system arranged to supply a liquid to a space between the projection system and the substrate. The apparatus also includes a liquid collecting system that includes a liquid collection member having a permeable member through which a liquid is collected from a surface of an object opposite to the liquid collection member, wherein the permeable member has a plurality of passages that generate a capillary force.
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This application claims the benefit under 35 USC §119(a)-(d) of European Application No. 10 014 616.6 filed Nov. 15, 2010, the entirety of which is incorporated herein by reference.
FIELD OF THE INVENTION
The invention relates to an apparatus for monitoring a door with a 3D sensor.
BACKGROUND OF THE INVENTION
Automatic doors and revolving doors may become dangerous to users if their danger zones in front of the door leaf are not monitored. Since the dangerous components move during the opening and closing process, the danger area to be monitored also concomitantly moves. Furthermore, the size of the area to be monitored must possibly change during movement. This results in the need to concomitantly move the monitoring sensor with the dangerous component, in which case adaptation to the wide variety of different door sizes and required monitoring areas is desirable. Economic factors also require the provision of a universal sensor with monitoring properties which can be easily adapted.
On account of the given requirements, the industry is looking for sensor solutions with flexible evaluation possibilities which evaluate, for example, the third dimension which relates to the distance between the object being monitored and the sensor. Such sensors can also be used for static mounting for monitoring applications for particular monitoring areas.
The prior art discloses active infrared sensors which are mounted on a door leaf and monitor the area in front of the plane of the door at a few points. As an alternative to this, laser sensors which scan the monitoring area using beams moved using rotation mechanisms are known. However, such sensors are very complex and are therefore associated with considerable production costs. In addition, these sensors provide considerably restricted convenience during installation and adaptation to the monitoring area since a multiplicity of optical components have to be aligned.
SUMMARY OF THE INVENTION
The object of the invention is therefore to provide an apparatus for monitoring a door with a 3D sensor, which apparatus improves the mounting and/or installation convenience in comparison with the prior art with reasonable costs.
The aim of the invention is to develop a universal monitoring sensor for automatic doors (revolving doors and double doors). In this case, the area to be monitored is intended to be easily and quickly adapted to the corresponding application and mounting position. The use of the TOF (Time-of-Flight) principle makes it possible to determine the distance of an object in the monitoring area as the third dimension. This makes it possible not only to monitor a precisely defined area but to set the sensor to a precisely defined monitoring volume using knowledge of the ambient conditions of the sensor. In this case, the sensor preferably consists of a compact unit which simultaneously comprises a transmitter and a receiver. In the first step, the scene to be monitored is illuminated using LEDs, for example. The emitted light is reflected and passes back into the sensor where it is detected using the receiving unit. The receiving part consists of a TOF chip with a plurality of pixels. Each pixel may receive a measurement beam reflected by an object. Modulated IR light is used for example. In order to determine the distance, a phase shift between the received signal and the emitted signal may be evaluated. The corresponding evaluation results in a distance value for each pixel, thus achieving a three-dimensional/volume-related capture image. The optics are designed in such a manner that the illumination remains focused in individual discrete beams, which results in corresponding spots with a high light intensity.
The use of a 3D sensor for monitoring enables more flexibility in the application-specific use. The sensor provides the distance values to the object, for example in a location-dependent manner (in the x-y plane or in the plane perpendicular to the sensor axis). In the case of 2D sensors, it is only possible to state whether an object is located within the beam under consideration. The position of the object is not resolvable. However, in the case of the TOF principle, the distance can also be used for evaluation, as a result of which new possibilities arise during the intelligent evaluation of these signals.
In an apparatus for monitoring a door with a 3D sensor which is able to detect distances to an object in the monitoring area as the third dimension, the 3D sensor being arranged in a housing, and immovably arranged transmission means for transmitting a measurement beam and receiver means for receiving the reflected measurement beam being provided in the housing, one aspect of the invention is that provision is made of a control unit which is designed to obtain information relating to the position of the apparatus, and the control unit evaluates the measurement beam on the basis of an item of position information. As a result, the mounting of a monitoring apparatus can be simplified and can be made more reliable. This is because, with an item of position information, the apparatus can unambiguously assign measurement beams detected after mounting to the environment and can thus also correctly evaluate said beams. In addition, it is possible for the apparatus to align itself as it were after mounting. For example, the control unit is designed to determine a mounting height of the apparatus after mounting by evaluating the measurement beam on the basis of the item of position information. It is thus no longer necessary to input a mounting height in order to calibrate the apparatus.
In one preferred refinement of the invention, the control unit is also designed to use a height of the mounting location as a parameter for defining the monitoring area. In order to be able to completely define the monitoring area, it is then only still necessary to specify the width of the monitoring area in the case of conventional double doors. Mounting and input errors can thus be minimized.
In order to also enable automation of the determination of a position and forwarding to the control unit, it is also proposed that there are position detection means which are designed to automatically detect a position, in particular an absolute position relative to a horizontal of the housing, and to forward said position to a control unit. An inclination sensor, for example, may be provided for comprehensive detection of the position of the apparatus. It is also conceivable to provide the control unit with position information, for example via input elements, for example DIP switches.
It is also possible to detect a position relative to a preassembled base plate automatically, for example via sensor means such as switching elements.
However, it is also conceivable to achieve mounting which is as error-free as possible using suitably designed mounting means. For example, the apparatus is designed to be fitted in a horizontal basic mounting position and to be fitted in at least two further different mounting positions relative to the horizontal basic mounting position, mounting means for the housing being designed for a mounting orientation which is always the same irrespective of the mounting position of the housing, and the mounting means and the housing being matched to one another in such a manner that a unique orientation of the housing on the mounting means in the respective at least two further mounting positions is provided by the mounting means.
The practice of specifying a basic position and at least two further mounting positions, which are in the form of defined positions, makes it considerably easier for an installer to mount and orient a corresponding 3D sensor, as a result of which positioning errors and resultant malfunctions are avoided.
In order to make mounting even more reliable, it is moreover proposed that the at least two further mounting positions relate to an arrangement of the apparatus in a corner area of a door to be monitored, the mounting means allowing the housing for the corner area to be fitted in a tilted manner with an orientation of the 3D sensor relative to the door to be monitored only in such a manner that a limiting monitoring beam of a monitoring area runs at least approximately parallel to an edge of the door to be monitored. In this connection, only three mounting positions of the housing are allowed. Mounting errors can thus be precluded with correct mounting, which is always the same, using mounting means for the three positions.
In order to simply fit the housing of the apparatus to the mounting means, it is also preferred if the mounting means comprise a frame which surrounds the housing. This frame is in the form of a bracket, for example, which runs across the front of the housing and the side walls of the housing to the mounting means.
In order to achieve a high resolution of the 3D sensor, it is also proposed that the 3D sensor in a housing comprises a receiver array and/or a sensor array. A receiver array makes it possible to evaluate a large number of measurement beams, in particular at the same time, in which case a transmitter array can be used to scan a comparatively large area, in particular with a plurality of measurement beams.
A transmitter matrix and a receiver matrix are used, in particular.
In order to carry out reliable object detection and evaluation, it is also preferred if the 3D sensor is an imaging sensor in which an object point is imaged onto an associated sensor point.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 a shows a mounted 3D sensor in the basic mounting position;
FIG. 1 b shows an exploded illustration of the sensor housing and of the apparatus for fitting the sensor;
FIG. 2 a shows a front view of the basic mounting position according to FIG. 1 a;
FIG. 2 b shows a first further mounting position;
FIG. 2 c shows a second further mounting position;
FIG. 3 a shows the fitting apparatus in the closed state;
FIG. 3 b shows the fitting apparatus in the open state;
FIG. 4 shows a rear-side illustration of the fitting apparatus and of the 3D sensor;
FIG. 5 shows a front view of the 3D sensor without the fitting apparatus; and
FIG. 6 shows an exemplary illustration of a mounting position.
FIG. 7 shows a first flowchart illustrating operation of an embodiment of the present invention.
FIG 8 shows a second flowchart illustrating operation of an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
In detail, FIG. 1 a shows an illustration of a housing 1 for an apparatus according to the invention for monitoring a door. The housing 1 is at least partially surrounded by a mounting frame 2 which engages in a mounting plate 3 on the rear side of the housing 1 . In this manner, the housing 1 is held on the mounting means formed by the mounting frame 2 and the mounting plate 3 .
FIG. 1 b shows an exploded illustration of the following parts: the housing 1 , the mounting frame 2 and the mounting plate 3 .
FIG. 2 a shows a frontal view of the arrangement according to FIG. 1 a . The housing 1 has a design corresponding to a segment of a circle on its right-hand and left-hand outer sides, the radius being adapted by the mounting frame, in particular in a manner matched to its inner side.
FIG. 2 b shows a first pivoted position of the housing 1 in the mounting frame 2 , the underside of the housing, on which the signals needed to monitor a door are emitted, being illustrated in the present case as having been pivoted to the right. The mounting frame 2 grips the housing 1 on the radius of the left-hand and right-hand side walls, with the result that the housing 1 is held by the mounting frame 2 with the mounting plate 3 (not illustrated here) as mounting means.
FIG. 2 c shows an arrangement of the apparatus according to the invention for monitoring a door, which arrangement has been accordingly pivoted to the left.
FIG. 3 a shows an illustration of the mounting means consisting of the mounting frame 2 and the mounting plate 3 without a housing arranged therein. The mounting means are preassembled by fitting the mounting plate 3 to a door, after which the housing 1 with the 3D sensor contained therein is introduced into the mounting means. The mounting plate is intended for a mounting position which is always the same, for example a horizontal position.
FIG. 3 b shows an exploded illustration of the mounting means formed from the mounting frame 2 and the mounting plate 3 . In this case, the mounting frame 2 has, on its ends facing the mounting plate 3 , latching hooks 2 a which engage in a form-fitting manner in corresponding receptacles 3 a on the mounting plate 3 . The mounting plate 3 also has two mounting slots 3 b which make it possible for the installer to carry out simple and precise mounting on a door leaf.
FIG. 4 shows an exploded illustration of a housing 1 arranged in a mounting frame. In this case, the housing 1 has a plurality of pins according to the invention on its rear side. In this case, the center pin 4 present is centrally arranged in the radius of the housing 1 , with the result that the housing 1 is rotatably mounted around the center pin 4 according to FIGS. 2 b and 2 c . Two lateral pins 5 which may preferably have latching clamping means are arranged along a horizontal direction of the housing 1 to the left and right of the center pin 4 .
The mounting plate 3 illustrated has, in its center, a central bore 6 for receiving the center pin 4 . According to the mounting positions illustrated in FIGS. 2 a to 2 c , the lateral pins 5 can be introduced, into corresponding bearing bores, the bearing bores always being arranged such that they are diagonally opposite in a rotationally symmetrical manner about the central bore 6 . The first bearing bores 7 a thus represent the horizontally planar mounting position. The second bearing bores 7 b correspond to the pivoting (illustrated in FIG. 2 b ) of the beam path to the right, and the third bearing bores 7 c correspond to the illustration according to FIG. 2 c . In this manner, the installer has a simple predefined pattern which considerably simplifies the mounting of the apparatus for monitoring a door without accepting disadvantages with regard to the mounting precision.
FIG. 5 shows an illustration of a housing 1 with a 3D sensor contained therein, operating elements 18 a , 18 b , 18 c , 18 d and 18 e , for example in the form of potentiometers or the like, being provided on the front side of the housing 1 . The operating elements are arranged in an operating element area 8 which is arranged on the front side of the housing such that it is easily accessible to the installer. The installer can carry out adaptations, for example to the mounting position, and/or can set the detection field of the apparatus for monitoring a door by means of corresponding adjustment parameters. As soon as the mounting frame 2 is arranged around the housing 1 , the mounting frame covers the central area 8 containing the accesses to the operating elements, the cover additionally being able to be a seal in all mounting positions.
FIG. 6 shows, by way of example, an arrangement of a 3D sensor according to the invention as an apparatus for monitoring a door, a double door 16 which is fastened on one side in the present case. In this case, the housing 1 is arranged, with the mounting frame 2 , in a left-hand upper corner area 17 of the door 16 . In this case, the door leaf 9 is fastened on the left-hand side by means of hinges 10 and has a door handle 11 on the right-hand side. The apparatus for monitoring a door is oriented in such a manner that it has a detection beam path 12 with an outer measurement beam 15 a , which beam path has been pivoted to the right according to the illustration in FIG. 2 b . On the left-hand side facing the hinges 10 , the beam path is oriented in such a manner that a measurement beam 15 b runs virtually perpendicular to the floor, that is to say in a virtually parallel manner along an edge 14 of a door leaf side 13 . Therefore, wall elements on which the hinges 10 are arranged are not detected during pivoting of the door leaf 9 .
The housing 1 is mounted on the door 16 , for example at a height h. Corresponding arrangements, both centrally and on the top right-hand side, with doors which are fastened in a different way are conceivable. Central arrangements may be expedient for double-wing doors. If necessary, the housing is fastened to the door frame or to the wall, rather than to the door.
The height of the door, inter alia, can also be determined using the vertical beams on the door leaf side 13 by measuring the distance to the reflective substrate. In this case, the height of the door should be stated with reference to a defined mounting position of the mounting means 2 , 3 , in which case this can be easily effected by the installer, for example by presenting a mounting template for the door edge.
For example, a position sensor which detects the orientation according to FIGS. 2 a , 2 b and 2 c is provided in the apparatus.
As an alternative to the position sensors, corresponding sensors which monitor the lateral pins and/or the bearing bores 7 a to 7 b , for example via push-buttons, in order to determine an orientation of the apparatus for monitoring a door therefrom are also conceivable.
Exact positions of individual objects in the danger zone of the door can be determined in this manner by means of appropriately adapted evaluation parts without having to carry out complicated highly precise mounting steps when arranging the apparatus according to the invention.
FIG. 7 shows a flowchart illustrating steps of operation of an embodiment of the present invention.
FIG. 8 shows a second flowchart illustrating steps of operation of an embodiment of the present invention that includes a transmitter array and a receiver array.
LIST OF REFERENCE SYMBOLS
1 Housing
2 Mounting frame
2 a Latching hook
3 Mounting plate
3 a Receptacles
3 b Mounting slots
4 Center pin
5 Lateral pin
6 Central bore
7 a First bearing bores
7 b Second bearing bores
7 c Third bearing bores
8 Operating element area
9 Door leaf
10 Hinge
11 Handle
12 Detecting beam path
13 Door leaf side
14 Door leaf edge
15 a Measurement beam
15 b Measurement beam
16 Double door
17 Corner area
18 a , 18 b , 18 c , 18 d and 18 e Operating elements
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An apparatus for monitoring a door with a 3D sensor which is able to detect distances to an object in the monitoring area as the third dimension, the 3D sensor being arranged in a housing, and immovably arranged transmission means for transmitting a measurement beam and receiver means for receiving a reflected measurement beam being provided in the housing, characterized in that provision is made of a control unit which is designed to obtain an item of information relating to the position of the apparatus, and in that the control unit evaluates the measurement beam on the basis of an item of position information.
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CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is a National Stage Application which claims priority of International Application No. PCT/EP12/061779, filed Jun. 20, 2012, which claims priority of U.S. Provisional Application No. 61/498,653, filed Jun. 20, 2011 and Danish Application No. PA201100465, filed Jun. 20, 2011. Each of these applications is hereby incorporated by reference in its entirety.
FIELD OF THE INVENTION
The present invention relates to 4-((1R,3S)-6-chloro-3-phenyl-indan-1-yl)-1,2,2-trimethyl-piperazine and the salts thereof with activity at dopamine D 1 and D 2 receptors as well as the serotonin 5HT 2 receptor for the treatment of diseases in the central nervous system in a once weekly dosing regime.
BACKGROUND OF THE INVENTION
4-((1R,3S)-6-chloro-3-phenyl-indan-1-yl)-1,2,2-trimethyl-piperazine and the salts thereof, pharmaceutical compositions containing these salts and the medical use thereof, including treatment of schizophrenia or other diseases involving psychotic symptoms, is disclosed in WO2005/016900. 4-((1R,3S)-6-chloro-3-phenyl-indan-1-yl)-1,2,2-trimethyl-piperazine is hereinafter referred to as Compound (I)
Compound (I) is also known as Zicronapine.
EP 638 073 covers a group of trans isomers of 3-aryl-1-(1-piperazinyl)indanes substituted in the 2- and/or 3-position of the piperazine ring. The compounds are described as having high affinity for dopamine D 1 and D 2 receptors and the 5-HT 2 receptor and are suggested to be useful for treatment of several diseases in the central nervous system, including schizophrenia.
Compound (I) above has been described by Bøgesø et al. in J. Med. Chem., 1995, 38, page 4380-4392, in the form of the fumarate salt, see table 5, compound (−)-38. This publication concludes that the (−)-enantiomers of compound 38 is a potent D 1 /D 2 antagonists showing some D 1 selectivity in vitro. The compound is also described as a potent 5-HT 2 antagonist. It is also mentioned that the compound does not induce catalepsy in rats.
The aetiology of schizophrenia is not known, but the dopamine hypothesis of schizophrenia formulated in the early 1960s, has provided a theoretical framework for understanding the biological mechanisms underlying this disorder (Carlsson, Am. J. Psychiatry 1978, 135, 164-173). In its simplest form, the dopamine hypothesis states that schizophrenia is associated with a hyperdopaminergic state, a notion which is supported by the fact that all antipsychotic drugs on the market today exert some dopamine D 2 receptor antagonism (Seeman Science and Medicine 1995, 2, 28-37). However, whereas it is generally accepted that antagonism of dopamine D 2 receptors in the limbic regions of the brain plays a key role in the treatment of positive symptoms of schizophrenia, the blockade of D 2 receptors in striatal regions of the brain causes extrapyramidal symptoms (EPS). As described in EP 638 073 a profile of mixed dopamine D 1 /D 2 receptor inhibition has been observed with some so-called “atypical” antipsychotic compounds, in particular with clozapine (8-chloro-11-(4-methylpiperazin-1-yl)-5H-dibenzo[b,e][1,4] diazepine), used in treatment of schizophrenic patients.
Further, selective D 1 antagonists have been connected to treatment of sleep disorders and alcohol abuse (D. N. Eder, Current Opinion in Investigational Drugs, 2002 3(2):284-288).
Dopamine may also play an important role in the aetiology of affective disorders (P. Willner, Brain. Res. Rev. 1983, 6, 211-224, 225-236 and 237-246; Bøgesø et al, J. Med. Chem., 1985, 28, 1817-1828).
In EP 638 073 is described how compounds having affinity for 5-HT 2 receptors, in particular 5-HT 2A receptor antagonists, have been suggested for treatment of different diseases, such as schizophrenia including the negative symptoms in schizophrenic patients, depression, anxiety, sleep disturbance, migraine attacks and neuroleptic-induced parkinsonism. 5-HT 2A receptor antagonism has also been suggested to reduce the incidence of extrapyramidal side effects induced by classical neuroleptics (Balsara et al. Psychopharmacology 1979, 62, 67-69).
Psychotic patients, and in particular schizophrenic patients, are often unwilling or unable to take their medication regularly; several studies have shown that a less frequent dosing results in higher degree of compliance and thus eventually better treatment of the patients. Therefore there is an unmet need for long acting preparations of antipsychotic medicine. In particular there is a need for long acting preparations of antipsychotic medicine in non-invasive form that represent an alternative to intra muscular depot formulations in order to make change in dosing regime, frequency of medication or type of medication, more flexible.
SUMMARY OF THE INVENTION
The inventors of the present invention have surprisingly found that the elimination half life of Compound (I) in human is about 150 hours. The long elimination half life in combination with affinity for both dopamine D1 and D2 receptors makes Compound (I) a putative long acting antipsychotic compound that can be administered weekly, biweekly or semiweekly in e.g. a non-invasive form, such as in an instant release formulation (IR-formulation), an extended, controlled or a delayed release formulation for oral administration.
Further, the inventors of the present invention have surprisingly found that the main metabolite of Compound (I) in human, namely trans-1(6-chloro-3-phenyl-indan-1-yl)-3,3-dimethyl-piperazine, Compound (II), and which also possesses affinity for both dopamine D1 and D2 receptors, has an elimination half life of about 300-400 hours.
This surprising combination of a long half life and affinity for both dopamine D1 and D2 receptors for Compound (I) and its main metabolite has lead the inventors of present invention to conclude that Compound (I) may be administered with a longer time interval than usually in the treatment of psychosis. Accordingly, it is anticipated that Compound (I) can be administered once weekly, twice weekly (semiweekly), or every second week (biweekly) in maintenance treatment of psychosis as well as in the treatment of acute exacerbation in psychosis.
The inventors of the present application have surprisingly found that dosing Compound (I) once weekly at a dose between about 30 mg/week and about 45 mg/week reduces the PANSS Total Score at least to the same extend as a daily dose of 10 mg/day. This allows for lower doses to be administered to humans i.e. less burden to the entire body, e.g. the liver, and a less frequent dosing.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 shows the study design applied for once weekly dosing of Compound (I)
DETAILED DESCRIPTION OF THE INVENTION
As already indicated Compound (I) is a putative antipsychotic compound with affinity for both dopamine D1 and D2 receptors. Preclinical experiments in rats using the condition avoidance response (CAR) model (Experimental procedure previously described in: Hertel P, Olsen C K, Arnt J., Eur. J. Pharmacol. 2002; 439(1-3):107-11.) have indicated that Compound (I) possesses antipsychotic activity at very low levels of D2 receptor occupancy.
In a positron emission tomography (PET) study in healthy subjects using 11 C-SCH23390 and 11 C-raclopride as D1 and D2 receptor tracers, it was found that Compound (I) induces a D2 receptor occupancy of from 11 to 43% in the putamen when increasing the dose from 2 to 10 mg/day given daily for 18 days. Such level of D2 receptor occupancy is low in comparison with that of currently used antipsychotic drugs, which in general requires a D2 receptor occupancy around or exceeding 50% to be therapeutically effective (Stone J M, Davis J M, Leucht S, Pilowsky L S. Schizophr Bull. 2008 Feb. 26). In the same PET study, it was found that Compound (I) induces a D1 receptor occupancy increase from 32 to 69% in putamen when increasing the dose from 2 to 10 mg/day given daily for 18 days. Such high level of D1 occupancy is not generally seen with current used antipsychotic drugs (Farde L, Nordstrom A L, Wiese F A, Pauli S, Halldin C, Sedvall G. Arch Gen Psychiatry. 1992; 49(7):538-44.). Thus, Compound (I) exhibits a unique ratio of D1 to D2 receptor occupancy.
Based on the above, it is expected that Compound (I) has clinically significant therapeutic effects in patients with schizophrenia at doses (from 4 mg/dose to 60 mg/dose) that induce only a low level of D2 receptor occupancy. This might well be a consequence of the high D1 receptor occupancy and the unique ratio of D1 versus D2 receptor occupancy displayed by Compound (I). A low D2 receptor occupancy at therapeutically effective doses will be beneficial in terms of reduced tendency to induce troublesome side effects mediated by D2 receptor blockade, including extrapyramidal side effects and hyperprolactinemia.
Compound (I) in a therapeutically effective amount of from 4-60 mg calculated as the free base is administered orally, and may be presented in any form suitable for such administration, e.g. in the form of tablets, capsules, powders, syrups or solutions.
In one embodiment, a salt of Compound (I) is administered in the form of a solid pharmaceutical entity, suitably as a tablet, such as an orally disintegrating tablet, or a capsule.
Pharmaceutically Acceptable Salts
The present invention also comprises salts of Compound (I), typically, pharmaceutically acceptable salts. Such salts include pharmaceutically acceptable acid addition salts. Acid addition salts include salts of inorganic acids as well as organic acids.
Representative examples of suitable inorganic acids include hydrochloric, hydrobromic, hydroiodic, phosphoric, sulfuric, sulfamic, nitric acids and the like. Representative examples of suitable organic acids include formic, acetic, trichloroacetic, trifluoroacetic, propionic, benzoic, cinnamic, citric, fumaric, glycolic, itaconic, lactic, methanesulfonic, maleic, malic, malonic, mandelic, oxalic, picric, pyruvic, salicylic, succinic, methane sulfonic, ethanesulfonic, tartaric, ascorbic, pamoic, bismethylene salicylic, ethanedisulfonic, gluconic, citraconic, aspartic, stearic, palmitic, EDTA, glycolic, p-aminobenzoic, glutamic, benzenesulfonic, p-toluenesulfonic acids, theophylline acetic acids, as well as the 8-halotheophyllines, for example 8-bromotheophylline and the like. Further examples of pharmaceutically acceptable inorganic or organic acid addition salts include the pharmaceutically acceptable salts listed in Berge, S. M. et al., J. Pharm. Sci. 1977, 66, 2, the contents of which are hereby incorporated by reference.
Furthermore, Compound (I) of this invention and salts thereof may exist in unsolvated as well as in solvated forms with pharmaceutically acceptable solvents such as water, ethanol and the like. In general, the solvated forms are considered comparable to the unsolvated forms for the purposes of this invention.
In a particular embodiment of the present invention Compound (I) is in the form of a succinate salt or a malonate salt.
Pharmaceutical Compositions
The present invention further provides a pharmaceutical composition comprising a therapeutically effective amount of Compound (I) of the present invention and a pharmaceutically acceptable carrier or diluent.
Compound (I) of the invention may be administered alone or in combination with pharmaceutically acceptable carriers, diluents or excipients, in either single or multiple doses. The pharmaceutical compositions according to the invention may be formulated with pharmaceutically acceptable carriers or diluents as well as any other known adjuvants and excipients in accordance with conventional techniques such as those disclosed in Remington: The Science and Practice of Pharmacy, 19 th Edition, Gennaro, Ed., Mack Publishing Co., Easton, Pa., 1995.
In a particular embodiment the pharmaceutical composition comprising Compound (I) disintegrates within 15 minutes, in particular within 10 minutes, such as 5 minutes, 4 minutes, 3 minutes, 2 minutes or 1 minute, as measured according to the procedure described in Remington's Pharmaceutical Sciences, 18 th edition (Ed. A. R. Genaro), 1990, pp. 1640-1641.
The pharmaceutical compositions may be specifically formulated for administration by any suitable route such as oral, nasal, topical (including buccal and sublingual), and parenteral (including subcutaneous, intramuscular, intrathecal, intravenous and intradermal) routes. It will be appreciated that the route will depend on the general condition and age of the subject to be treated, the nature of the condition to be treated and the active ingredient.
Compound (I) of this invention is generally utilized as the free substance or as a pharmaceutically acceptable salt thereof. Examples of suitable organic and inorganic acids are described above.
Dosing Regime
Long acting antipsychotic compound, long acting preparations, and long acting preparations of antipsychotic compounds refer to compounds and preparations of compounds that maintain pharmaceutically active levels of the exogenously administered compound for more than one day, such as for a week, so that the compound need not to be given on a daily basis but semiweekly, weekly or even biweekly.
The present invention relates to Compound (I) for the treatment of a disease in the central nervous system, including psychosis, in particular schizophrenia or other diseases involving psychotic symptoms, such as, e.g. Schizophreniform Disorder, Schizoaffective Disorder, Delusional Disorder, Brief Psychotic Disorder, Shared Psychotic Disorder as well other psychotic disorders or diseases that present with psychotic symptoms, e.g. bipolar disorder, such as mania in bipolar disorder, wherein Compound (I) is administered semiweekly, weekly or biweekly.
The invention also relates to a method for the medical use of Compound (I), such as for the treatment of a disease in the central nervous system, including psychosis, in particular schizophrenia or other diseases involving psychotic symptoms, such as, e.g. Schizophreniform Disorder, Schizoaffective Disorder, Delusional Disorder, Brief Psychotic Disorder, Shared Psychotic Disorder as well other psychotic disorders or diseases that present with psychotic symptoms, e.g. bipolar disorder, such as mania in bipolar disorder, wherein Compound (I) is administered semiweekly, weekly or biweekly.
The weekly (i.e. with an interval of 7 days) or semiweekly (i.e. twice a week with a 3 to 4 days interval) or biweekly (i.e. with and interval of 14 days) dose of Compound (I), calculated as the free base, is suitably between 1 mg/dose and 100 mg/dose, more suitable between 1 mg/dose and 60 mg/dose, e.g. preferably between 5 mg/dose and 55 mg/dose, such as between 10 mg/dose and 45 mg/dose mg, in particular between 30 mg/dose and 45 mg/dose, such as 40 ring/dose or 45 ring/dose.
Accordingly, in a specific embodiment the invention relates to Compound (I) for the treatment of a disease in the central nervous system, characterized in that Compound (I) is administered semiweekly, weekly or biweekly in a dose corresponding to between 20 mg/week and 50 mg/week calculated as the free base of Compound (I)
The weekly, semiweekly (i.e. twice a week with a 3 to 4 days interval) or biweekly (i.e. with and interval of 14 days) administration of Compound (I) may be for the maintenance treatment of a disease in the central nervous system, in particular psychosis, as well as for the treatment of acute exacerbation in psychosis.
Maintenance treatment is designed to prevent relapse once patients have been stabilized by either Compound (I) of the present invention or by a different anti-psychotic compound.
Acute exacerbation is a sudden worsening of the psychotic conditions.
All references, including publications, patent applications and patents, cited herein are hereby incorporated by reference in their entirety and to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety (to the maximum extent permitted by law).
Headings and sub-headings are used herein for convenience only, and should not be construed as limiting the invention in any way.
The use of any and all examples, or exemplary language (including “for instance”, “for example”, “e.g.”, and “as such”) in the present specification is intended merely to better illuminate the invention, and does not pose a limitation on the scope of invention unless otherwise indicated.
As used herein the term “about” is used herein to mean approximately, roughly, around, or in the region of. When the term “about” is used in conjunction with a numerical range, it modifies that range by extending the boundaries above and below the numerical values set forth. In general, the term “about” is used herein to modify a numerical value above and below the stated value by a variance of 10 percent up or down (higher or lower).
As used herein the term “between” used in conjunction with a numerical range includes the lower and upper value (the end points) of the range.
The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context.
Unless otherwise indicated, all exact values provided herein are representative of corresponding approximate values (e.g., all exact exemplary values provided with respect to a particular factor or measurement can be considered to also provide a corresponding approximate measurement, modified by “about,” where appropriate).
The description herein of any aspect or aspect of the invention using terms such as “comprising”, “having,” “including,” or “containing” with reference to an element or elements is intended to provide support for a similar aspect or aspect of the invention that “consists of”, “consists essentially of”, or “substantially comprises” that particular element or elements, unless otherwise stated or clearly contradicted by context.
The citation and incorporation of patent documents herein is done for convenience only, and does not reflect any view of the validity, patentability and/or enforceability of such patent documents.
The present invention includes all modifications and equivalents of the subject-matter recited in the claims appended hereto, as permitted by applicable law.
EXPERIMENTAL
Binding Assays
Description of Human D 2 Binding Assay
The assay can be performed as a SPA-based competition-binding in a 50 mM Tris pH 7.4 assay buffer containing 120 mM NaCl, 5 mM KCl, 4 mM MgCl 2 , 1.5 mM CaCl 2 , 1 mM EDTA.
1.5 nM 3 H-raclopride (Perkin Elmer, NET 975) is mixed with test compound before addition of 20 microg of a homogenised human D 2 receptor membrane-preparation and 0.25 mg SPA beads (WGA RPNQ 0001, Amersham) in a total volume of 90 microL. The assay plates are under agitation incubated for 60 minutes at room temperature and subsequently counted in a scintillation counter (TriLux, Wallac). The total binding, which comprised approximately 15% of added radioligand, is defined using assay buffer, whereas the non-specific binding is defined in the presence of 10 microM haloperidol. The non-specific binding constituted approximately 10% of the total binding.
Data points are expressed in percent of the specific binding of 3 H-Raclopride and the IC 50 values (concentration causing 50 percent inhibition of 3 H-raclopride specific binding) are determined by non-linear regression analysis using a sigmoidal variable slope curve fitting. The dissociation constant (K i ) is calculated from the Cheng Prusoff equation (K i =IC 50 /(1+(L/K D )), where the concentration of free radioligand L is approximated to the concentration of added 3 H-raclopride in the assay. The K D of 3 H-raclopride is determined to 1.5 nM from two independent saturation assays each performed with triplicate determinations.
Description of Human D 1 Binding Assay
The assay is performed as a SPA-based competition-binding in a 50 mM Tris pH 7.4 assay buffer containing 120 mM NaCl, 5 mM KCl, 4 mM MgCl 2 , 1.5 mM CaCl 2 , 1 mM EDTA. Approximately 1 nM 3 H-SCH23390 (Perkin Elmer, NET 930) is mixed with test compound before addition of 2.5 microg of a homogenized human D 1 receptor membrane-preparation and 0.25 mg SPA beads (WGA RPNQ 0001, Amersham) in a total volume of 60 microL.
The assay plates are under agitation incubated for 60 minutes at room temperature before the plates are centrifuged and subsequently counted in a scintillation counter (TriLux, Wallac). The total binding, which comprised approximately 15% of added radioligand, is defined using assay buffer whereas the non-specific binding is defined in the presence of 10 microM haloperidol.
Data points are expressed in percent of the specific binding and the IC 50 values (concentration causing 50 percent inhibition of specific binding) and are determined by non-linear regression analysis using a sigmoidal variable slope curve fitting. The dissociation constant (K i ) is calculated from the Cheng Prusoff equation (K i =IC 50 /(1+(L/K D )), where the concentration of free radioligand L is approximated to the concentration of added radio-ligand in the assay.
Description of Human 5-HT2 A Binding
The experiment is carried out at Cerep Contract Laboratories (Cat. ref. #471).
Description of In Vivo Binding to D 2 Receptors in Rat Brain
In vivo binding is carried out according to Andersen et al (Eur J Pharmacol, (1987) 144:1-6) with a few modifications (Kapur S. et al, J Pharm Exp Ther, 2003, 305, 625-631). Briefly, 6 rats (male Wistar, 180-200 g) are treated with 20 mg/kg test compound subcutaneous 30 minutes before receiving 9.4 micro Ci [ 3 H]-raclopride intravenous via the tail vein.
15 minutes after the injection of the radio ligand the animals are killed by cervical dislocation, the brain quickly removed and striatum and cerebellum dissected out and homogenized in 5 mL (cerebellum in 20 mL) ice-cold buffer (50 mM K 2 PO 4 , pH 7.4). 1.0 mL of the homogenate is filtered through 0.1% PEI—soaked Whatman GF/C filters. This is completed within 60 seconds subsequent to the decapitation. Filters are washed 2 times with 5 mL ice-cold buffer and counted in a scintillation counter. A group of vehicle treated animals is used to determine [ 3 H]-raclopride total binding in striatum and non-specific binding in cerebellum. The homogenate is measured for protein content by the BCA protein determination assay (Smith P. K. et al (1985) Anal. Biochem., 150: 6-85).
Example 1
Binding Affinity of Compound (I)
Previously conducted in vitro binding studies have shown that Compound (I) binds to the D1, D 2 and 5-HT 2 A receptors with the following affinities:
Human D 1 binding: K i =19 nM
Human 5-HT2 A binding: K i =4.2 nM
In vivo binding to D 2 receptors in brain: ED 50 =4.1 mg/kg
Example 2
Study Design
The design of the study that was conducted to evaluate the feasibility of a once weekly dosing of Compound (I), administered in the form of hydrogen succinate salt of Compound (I), is out-lined in FIG. 1 . The study is a randomized, double-blind, parallel-group, exploratory study of safety, tolerability and PK of daily dosing vs weekly dosing of Compound (I) in schizophrenic patients.
The open-label period (OL_Period) is the period from start of open-label treatment (baseline) until stop of open-label treatment (at OL-withdrawal or randomisation to double-blind treatment, whichever occurs first).
The placebo period (PBO_Period) is the first week of double-blind treatment where patients randomised to weekly dosing receive placebo treatment, while patients randomised to daily dosing continue treatment with 10 mg/day Compound (I)
The double-blind period (DB_Period) is the period from start of double-blind treatment (randomisation) until stop of double-blind treatment (at DB-withdrawal or completion, whichever occurs first), that is, the entire double-blind period including the PBO_Period.
The IMP dosing period (IMP_Period) is the period from start of open-label treatment (baseline) until stop of double-blind treatment (at withdrawal or completion, whichever occurs first), that is, the OL_Period plus the DB_Period.
Example 3
Changes from Randomization in PANSS Total Score
A study was conducted with a study design as described in Example 2.
Results as changes from randomization in PANSS Total Score are provided in table 1:
TABLE 1 PANSS Total Score Mean Treatment group Study day N (change in PANSS) Compound (I) 29 11 1.55 10 mg/day 36 10 −1.00 43 10 −2.50 50 10 −3.50 57 10 −5.80 Compound (I) 29 10 0.00 20 mg/week 36 10 0.80 43 8 −2.00 50 9 −1.22 57 8 −4.38 Compound (I) 29 11 1.09 30 mg/week 36 10 0.50 43 8 4.00 50 7 −4.14 57 7 −5.43 Compound (I) 29 10 0.40 45 mg/week 36 10 −3.50 43 10 −5.70 50 10 −8.00 57 8 −6.88
The above data shows that once weekly dosing in the range of 20 mg/week to 45 mg/week, in particular 30 mg/week and 45 mg/week, is as effective in reduction in PANSS Total Score as a daily dose of 10 mg/day.
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The present invention relates to 4-((1R,3S)-6-chloro-3-phenyl-indan-1-yl)-1,2,2-trimethyl-piperazine and the salts thereof with activity at dopamine D 1 and D 2 receptors as well as the serotonin 5HT 2 receptor for the treatment of diseases in the central nervous system in a once weekly dosing regime.
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FIELD OF THE INVENTION
The invention relates to the field of integrated circuit packaging. In particular, the encapsulation of the wire bonds between a circuit board and the contact pads on the integrated circuit die.
CO-PENDING APPLICATIONS
The following applications have been filed by the Applicant simultaneously with the present application:
11860538
11860540
11860541
11860542
The disclosures of these co-pending applications are incorporated herein by reference.
CROSS REFERENCES TO RELATED APPLICATIONS
Various methods, systems and apparatus relating to the present invention are disclosed in the following U.S. Patents/Patent Applications filed by the applicant or assignee of the present invention:
6,405,055
6,628,430
7,136,186
10/920,372
7,145,689
7,130,075
7,081,974
7,177,055
7,209,257
7,161,715
7,154,632
7,158,258
7,148,993
7,075,684
7,158,809
11/225,172
11/474,280
11/635,482
11/635,526
11/650,545
11/653,241
11/653,240
11,758,648
7,241,005
7,108,437
6,915,140
6,999,206
7,136,198
7,092,130
7,249,108
6,566,858
6,331,946
6,246,970
6,442,525
09/517,384
09/505,951
6,374,354
7,246,098
6,816,968
6,757,832
6,334,190
6,745,331
7,249,109
10/203,559
7,197,642
7,093,139
10/636,263
10/636,283
10/866,608
7,210,038
10/902,833
10/940,653
10/942,858
11/706,329
11/757,385
11/758,642
7,170,652
6,967,750
6,995,876
7,099,051
11/107,942
7,193,734
11/209,711
11/599,336
7,095,533
6,914,686
7,161,709
7,099,033
11/003,786
7,258,417
11/003,418
11/003,334
11/003,600
11/003,404
11/003,419
11/003,700
7,255,419
11/003,618
7,229,148
7,258,416
11/003,698
11/003,420
6,984,017
11/003,699
11/071,473
11,748,482
11/778,563
11/779,851
11/778,574
11/853,816
11/853,814
11/853,786
11/856,694
11/003,463
11/003,701
11/003,683
11/003,614
11/003,702
11/003,684
7,246,875
11/003,617
11/764,760
11,853,777
11/293,800
11/293,802
11/293,801
11/293,808
11/293,809
11/482,975
11/482,970
11/482,968
11/482,972
11/482,971
11/482,969
11/097,266
11/097,267
11/685,084
11/685,086
11/685,090
11/740,925
11/763,444
11/763,443
11/518,238
11/518,280
11/518,244
11/518,243
11/518,242
11/084,237
11/084,240
11/084,238
11/357,296
11/357,298
11/357,297
11/246,676
11/246,677
11/246,678
11/246,679
11/246,680
11/246,681
11/246,714
11/246,713
11/246,689
11/246,671
11/246,670
11/246,669
11/246,704
11/246,710
11/246,688
11/246,716
11/246,715
11/246,707
11/246,706
11/246,705
11/246,708
11/246,693
11/246,692
11/246,696
11/246,695
11/246,694
11/482,958
11/482,955
11/482,962
11/482,963
11/482,956
11/482,954
11/482,974
11/482,957
11/482,987
11/482,959
11/482,960
11/482,961
11/482,964
11/482,965
11/482,976
11/482,973
11/495,815
11/495,816
11/495,817
6,227,652
6,213,588
6,213,589
6,231,163
6,247,795
6,394,581
6,244,691
6,257,704
6,416,168
6,220,694
6,257,705
6,247,794
6,234,610
6,247,793
6,264,306
6,241,342
6,247,792
6,264,307
6,254,220
6,234,611
6,302,528
6,283,582
6,239,821
6,338,547
6,247,796
6,557,977
6,390,603
6,362,843
6,293,653
6,312,107
6,227,653
6,234,609
6,238,040
6,188,415
6,227,654
6,209,989
6,247,791
6,336,710
6,217,153
6,416,167
6,243,113
6,283,581
6,247,790
6,260,953
6,267,469
6,588,882
6,742,873
6,918,655
6,547,371
6,938,989
6,598,964
6,923,526
6,273,544
6,309,048
6,420,196
6,443,558
6,439,689
6,378,989
6,848,181
6,634,735
6,299,289
6,299,290
6,425,654
6,902,255
6,623,101
6,406,129
6,505,916
6,457,809
6,550,895
6,457,812
7,152,962
6,428,133
7,216,956
7,080,895
11/144,844
7,182,437
11/599,341
11/635,533
11/607,976
11/607,975
11/607,999
11/607,980
11/607,979
11/607,978
11/735,961
11/685,074
11/696,126
11/696,144
11/696,650
11/763,446
10/407,212
7,252,366
10/683,064
10/683,041
11,766,713
11/841,647
11/482,980
11/563,684
11/482,967
11/482,966
11/482,988
11/482,989
11/293,832
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11/293,841
11/293,799
11/293,796
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11/124,158
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11/124,192
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11/124,163
11/124,149
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7,236,271
11/124,174
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11/829,962
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11/829,966
11/829,967
11/829,968
11/829,969
7,156,508
7,159,972
7,083,271
7,165,834
7,080,894
7,201,469
7,090,336
7,156,489
10/760,233
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7,077,505
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10/760,189
7,198,355
10/760,232
10/760,231
7,152,959
7,213,906
7,178,901
7,222,938
7,108,353
7,104,629
11/446,227
11/454,904
11/472,345
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7,261,401
11/474,279
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11/482,950
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11/601,668
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11,782,593
11/246,684
11/246,672
11/246,673
11/246,683
11/246,682
60/939,086
7,246,886
7,128,400
7,108,355
6,991,322
10/728,790
7,118,197
10/728,784
10/728,783
7,077,493
6,962,402
10/728,803
7,147,308
10/728,779
7,118,198
7,168,790
7,172,270
7,229,155
6,830,318
7,195,342
7,175,261
10/773,183
7,108,356
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10/773,186
7,134,744
10/773,185
7,134,743
7,182,439
7,210,768
10/773,187
7,134,745
7,156,484
7,118,201
7,111,926
10/773,184
7,018,021
11/060,751
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7,128,402
11/298,774
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7,246,885
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11/592,995
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11/706,378
11/706,962
11,749,118
11/754,937
11,749,120
11/744,885
11/779,850
11/765,439
11,842,950
11/839,539
11/097,308
11/097,309
7,246,876
11/097,299
11/097,310
11/097,213
11/210,687
11/097,212
7,147,306
7,261,394
11/764,806
11/782,595
11/482,953
11/482,977
11/544,778
11/544,779
11/764,808
09/575,197
7,079,712
6,825,945
09/575,165
6,813,039
6,987,506
7,038,797
6,980,318
6,816,274
7,102,772
09/575,186
6,681,045
6,728,000
7,173,722
7,088,459
09/575,181
7,068,382
7,062,651
6,789,194
6,789,191
6,644,642
6,502,614
6,622,999
6,669,385
6,549,935
6,987,573
6,727,996
6,591,884
6,439,706
6,760,119
09/575,198
6,290,349
6,428,155
6,785,016
6,870,966
6,822,639
6,737,591
7,055,739
7,233,320
6,830,196
6,832,717
6,957,768
09/575,172
7,170,499
7,106,888
7,123,239
11/066,161
11/066,160
11/066,159
11/066,158
11/066,165
10/727,181
10/727,162
10/727,163
10/727,245
7,121,639
7,165,824
7,152,942
10/727,157
7,181,572
7,096,137
10/727,257
10/727,238
7,188,282
10/727,159
10/727,180
10/727,179
10/727,192
10/727,274
10/727,164
10/727,161
10/727,198
10/727,158
10/754,536
10/754,938
10/727,227
10/727,160
10/934,720
7,171,323
11/272,491
11/474,278
11/488,853
11/488,841
11,749,750
11,749,749
10/296,522
6,795,215
7,070,098
7,154,638
6,805,419
6,859,289
6,977,751
6,398,332
6,394,573
6,622,923
6,747,760
6,921,144
10/884,881
7,092,112
7,192,106
11/039,866
7,173,739
6,986,560
7,008,033
11/148,237
7,222,780
11/248,426
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11/752,900
7,195,328
7,182,422
11/650,537
11/712,540
10/854,521
10/854,522
10/854,488
10/854,487
10/854,503
10/854,504
10/854,509
7,188,928
7,093,989
10/854,497
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10/854,498
10/854,511
10/854,512
10/854,525
10/854,526
10/854,516
10/854,508
7,252,353
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10/854,491
10/854,528
10/854,523
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10/854,524
10/854,520
10/854,514
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10/854,513
10/854,499
10/854,501
7,266,661
7,243,193
10/854,518
10/854,517
10/934,628
7,163,345
11/499,803
11/601,757
11/706,295
11/735,881
11,748,483
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11/293,792
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11/293,826
11/293,829
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11/293,795
11/293,823
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11/293,831
11/293,815
11/293,819
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11/838,875
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7,156,511
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7,201,470
7,121,655
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7,255,430
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11/688,863
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11/482,984
11/495,818
11/495,819
11/677,049
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11/677,051
11/014,722
10/760,180
7,111,935
10/760,213
10/760,219
10/760,237
7,261,482
10/760,220
7,002,664
10/760,252
10/760,265
7,088,420
11/446,233
11/503,083
11/503,081
11/516,487
11/599,312
11/014,728
11/014,727
7,237,888
7,168,654
7,201,272
6,991,098
7,217,051
6,944,970
10/760,215
7,108,434
10/760,257
7,210,407
7,186,042
10/760,266
6,920,704
7,217,049
10/760,214
10/760,260
7,147,102
10/760,269
7,249,838
10/760,241
10/962,413
10/962,427
7,261,477
7,225,739
10/962,402
10/962,425
10/962,428
7,191,978
10/962,426
10/962,409
10/962,417
10/962,403
7,163,287
7,258,415
10/962,523
7,258,424
10/962,410
7,195,412
7,207,670
11/282,768
7,220,072
11/474,267
11/544,547
11/585,925
11/593,000
11/706,298
11/706,296
11/706,327
11/730,760
11/730,407
11/730,787
11/735,977
11/736,527
11/753,566
11/754,359
11/778,061
11/765,398
11/778,556
11/829,937
11/780,470
11/223,262
11/223,018
11/223,114
11/223,022
11/223,021
11/223,020
11/223,019
11/014,730
7,154,626
7,079,292
11/604,316
The disclosures of these co-pending applications are incorporated herein by reference.
BACKGROUND OF THE INVENTION
Integrated circuits fabricated on silicon wafer substrates are electrically connected to printed circuit boards by wire bonds. The wire bonds are very thin wires—around 25 to 40 microns in diameter—extending from contact pads along the side of the wafer substrate to contacts on the printed circuit board (PCB). To protect and strengthen the wire bonds, they are sealed within a bead of epoxy called encapsulant. The wires from the contact pads to the PCB are made longer than necessary to accommodate changes in the gap between the PCB and the contact pads because of thermal expansion, flex in the components and so on. These longer than necessary wires naturally form an arc between the contact pads and the PCB. The top of the wire arc is often about 300 microns above the contact pads although some wire bonding may extend even higher. As the name suggests, the encapsulant needs to encapsulate the full length of the wire so the encapsulant bead will extend 500 microns to 600 microns proud of the contact pads.
The integrated circuit fabricated on the silicon wafer is often referred to as a ‘die’. For the purposes of this specification, the term die will be used as a reference to an integrated circuit fabricated on a wafer substrate using lithographic the well known etching and deposition techniques commonly used in semiconductor fabrication. If the die is purely an electronic microprocessor, there is little need to keep close control of the encapsulant bead dimensions. However, if the die is a micro-electro mechanical systems (MEMS) device with an active upper surface, it may be necessary or desirable to bring the active surface of the die onto close proximity with another surface. One such situation applies to inkjet printheads. The proximity of the print media to the nozzle array influences the print quality. Similarly, if a cleaning surface is wiped across the nozzles, the bead of encapsulant can hamper the wiping contact.
Another problems arises because of sides of the encapsulant bead are not straight. One commonly used technique for depositing the encapsulant involves extruding it from a needle directly onto the line of wire bonds. The encapsulant volume and placement on the die is not very accurate. Variations in the pressure from the pump or slight non-uniformities in the speed of the needle cause the side of the bead contacting the active surface to be reasonably crooked. As the side of the bead is not straight, it has to be generously spaced from any active parts on the active surface to comfortably accommodate the perturbations. Spacing the electrical contacts away from the active portions (say for example, inkjet nozzles) of the active surface uses up valuable wafer real estate and reduces the number of dies that can be fabricated from a wafer disc.
In light of the widespread use of inkjet printheads, the invention will be described with specific reference to its application in this field. However, the ordinary will appreciate that this is purely illustrative and the invention is equally applicable to other integrated circuits wire bonded to a PCB or other support structure.
SUMMARY OF THE INVENTION
According to a first aspect, the present invention provides a microprocessor device comprising:
a support structure having a chip mounting area and a conductor mounting area;
a die supported on the chip mounting area, the die having a back surface in contact with the chip mounting area and an active surface opposing the back surface, the active surface having electrical contact pads;
a plurality of electrical conductors at least partially supported on the conductor mounting area; and,
a series of wire bonds extending from the electrical contact pads to the plurality of electrical conductors supported on the conductor mounting area; wherein,
the chip mounting area is raised relative to the conductor mounting area.
By raising the chip mounting area relative to the rest of the PCB, or at least the conductors connected to the PCB end of the wire bonds, the top of the arc formed by the layer is much closer to the active surface of the die. This, in turn, allows the bead of encapsulant to have a lower profile relative to the active surface. With a lower encapsulant bead, the active surface can be brought into closer proximity with another surface without making contact. For example, the nozzle array on a printhead IC can be 300 microns to 400 microns from the paper path.
Preferably, the chip mounting area is raised more than 100 microns relative to the conductor mounting area. Preferably, the support structure has a step between the chip mounting area and the conductor mounting area.
Preferably, the plurality of conductors are incorporated into a flexible printed circuit board (flex PCB) with a line of bond pads along an edge closest the die, the bond pads being more than 2 mm from the contacts pads on the die.
Preferably, the wire bonds are formed from wire with a diameter less than 40 microns and extend less than 100 microns above the active surface of the die.
Preferably, the wire bonds are plastically deformed such that they extend less than 50 microns above the active surface of the die.
Preferably, the active surface has functional elements spaced less than 260 microns from the contacts pads of the die. In a particularly preferred form, the die is an inkjet printhead IC and the functional elements are nozzles through which ink is ejected. In some embodiments, the support structure is a liquid crystal polymer (LCP) molding.
Preferably, the wire bonds are covered in a bead of encapsulant, the bead of encapsulant extending less than 200 microns above the active surface of the die.
Preferably, the wire bonds are covered in a bead of encapsulant, the bead of encapsulant having a profiled surface that is flat, parallel to and spaced less than 100 microns from the active surface.
Preferably, the wire bonds are covered in a bead of encapsulant, the bead of encapsulant having a profiled surface that is flat and inclined relative to the active surface.
Preferably, the wire bonds are covered in a bead of encapsulant, the encapsulant being an epoxy material that is thixotropic when uncured.
Preferably, the wire bonds are covered in a bead of encapsulant, the encapsulant being an epoxy material has a viscosity greater than 700 cp when uncured.
In a particular embodiment, the printhead IC is mounted in a printer such that during use the nozzles are less than 100 microns from the paper path.
According to a second aspect, the present invention provides a method of profiling a wire bond between a contact pad on a die, and a conductor on a supporting structure, the method comprising the steps of:
electrically connecting the contact pad on the die to the conductor on the supporting structure with a wire bond, the wire bond extending in an arc from the contact pad to the conductor;
pushing on the wire bond to collapse the arc and plastically deform the wire bond; and,
releasing the wire bonds such that the plastic deformation maintains the wire bond in a flatter profile shape.
The strength of the wire bond is known to be relatively small; of the order of 3 to 5 grams force. However, the Applicant's work has found that the wire bond structure is robust enough to withstand a certain degree of work hardening from plastic deformation. The arc of the wire bond can be deformed into a flatter profile without compromising the electrical connection with the PCB.
Preferably, the die has an active surface that has functional elements, the contacts pad being formed at one edge of the active surface, the wire bond has a diameter less than 40 microns and the arc extends more than 100 microns above the active surface of the die.
Preferably, the wire bond is plastically deformed such that it extends less than 50 microns above the active surface of the die.
Preferably, the wire bond is pushed by engagement with a blade having a rounded edge section for contacting the wire bond.
Preferably, the method further comprises the steps of:
applying a bead of encapsulant over the wire bond; and,
moving a profiling surface over the active surface to flatten the bead of encapsulant.
Preferably, the bead of encapsulant having a profiled surface that is flat, parallel to and spaced less than 100 microns from the active surface.
Optionally, the bead of encapsulant having a profiled surface that is flat and inclined relative to the active surface.
Preferably, the encapsulant being an epoxy material has a viscosity greater than 700 cp when uncured. In a particularly preferred form, the encapsulant being an epoxy material that is thixotropic when uncured.
Preferably, the method further comprises the steps of:
positioning the profiling surface adjacent and spaced from the active surface to define a gap; and,
applying the bead of encapsulant onto the contact pads such that one side of the bead contacts the profiling surface and a portion of the bead extends into the gap and onto the active surface.
Preferably, the active surface has functional elements spaced less than 260 microns from the contacts pads of the die. In a particularly preferred form, the die is an inkjet printhead IC and the functional elements are nozzles through which ink is ejected. In some embodiments, the printhead IC is mounted in a printer such that during use the nozzles are less than 100 microns from the paper path.
Preferably, the support structure has a chip mounting area and a conductor mounting area, the die is supported on the chip mounting area, and a plurality of electrical conductors at least partially supported on the conductor mounting area wherein, the chip mounting area is raised relative to the conductor mounting area.
Preferably, the chip mounting area is raised more than 100 microns relative to the conductor mounting area. Preferably, the support structure has a step between the chip mounting area and the conductor mounting area. In some embodiments, the plurality of conductors are incorporated into a flexible printed circuit board (flex PCB) with a line of bond pads along an edge closest the die, the bond pads being more than 2 mm from the contacts pads on the die.
Preferably, the support structure is a liquid crystal polymer (LCP) molding.
According to a third aspect, the present invention provides a method for profiling a bead of encapsulant extending along an edge of a die mounted to a supporting structure, the method comprising the steps of:
depositing a bead of encapsulant onto wire bonds along the edge of the die;
positioning a profiling surface over the die at a predetermined spacing from the die;
moving the profiling surface across the bead before the bead of encapsulant has cured to reshape the bead profile; and,
curing the bead of encapsulant.
The invention has found that the encapsulant can be effectively shaped by a profiling surface without stripping the encapsulant from the wire bonds. The normally convex-shaped upper surface of the encapsulant bead can be pushed to one side of the bead with the profiling surface. With a lower encapsulant bead, the active surface can be brought into closer proximity with another surface without making contact. For example, the nozzle array on a printhead IC can be 300 microns to 400 microns from the paper path. By collapsing or flattening the wire bond arcs before applying and profiling a bead of encapsulant, the nozzle array on the printhead IC can be less than 100 microns from the paper path.
Preferably, the wire bonds extend in an arc from respective contact pads on the die to corresponding conductors on the support structure and the method further comprises the steps of:
pushing on the wire bonds to plastically deform the wire bonds; and,
releasing the wire bond such that plastic deformation maintains the wire bond in a flatter profile shape.
Preferably, the die has an active surface that has functional elements, the contacts pad being formed at one edge of the active surface, the wire bond has a diameter less than 40 microns and the arc extends more than 100 microns above the active surface of the die.
Preferably, the wire bond is plastically deformed such that it extends less than 50 microns above the active surface of the die.
Preferably, the wire bond is pushed by engagement with a blade having a rounded edge section for contacting the wire bond.
Preferably, the bead of encapsulant has a profiled surface that is flat, parallel to and spaced less than 100 microns from the active surface.
Preferably, the bead of encapsulant has a profiled surface that is flat and inclined relative to the active surface.
Preferably, the encapsulant being an epoxy material has a viscosity greater than 700 cp when uncured.
Preferably, the encapsulant being an epoxy material that is thixotropic when uncured.
Preferably, the method further comprises the steps of:
positioning the profiling surface adjacent and spaced from the active surface to define a gap; and,
applying the bead of encapsulant onto the contact pads such that one side of the bead contacts the profiling surface and a portion of the bead extends into the gap and onto the active surface.
Preferably, the active surface has functional elements spaced less than 260 microns from the contacts pads of the die. In a further preferred form, the die is an inkjet printhead IC and the functional elements are nozzles through which ink is ejected. In some embodiments, the printhead IC is mounted in a printer such that during use the nozzles are less than 100 microns from the paper path.
Preferably, the support structure has a chip mounting area and a conductor mounting area, the die is supported on the chip mounting area, and a plurality of electrical conductors at least partially supported on the conductor mounting area wherein, the chip mounting area is raised relative to the conductor mounting area.
Preferably, the chip mounting area is raised more than 100 microns relative to the conductor mounting area. In a particularly preferred form, the support structure has a step between the chip mounting area and the conductor mounting area.
Preferably, the plurality of conductors are incorporated into a flexible printed circuit board (flex PCB) with a line of bond pads along an edge closest the die, the bond pads being more than 2 mm from the contacts pads on the die.
Preferably, the support structure is a liquid crystal polymer (LCP) molding.
According to a fourth aspect, the present invention provides a method of applying encapsulant to a die mounted to a support structure, the method comprising the steps of:
providing a die mounted to the support structure, the die having a back surface in contact with the support structure and an active surface opposing the back surface, the active surface having electrical contact pads;
positioning a barrier proximate the electrical contact pads and spaced from the active surface to define a gap; and,
depositing a bead of encapsulant onto the electrical contact pads such that one side of the bead contacts the barrier and a portion of the bead extends into the gap and onto the active surface.
Placing a barrier over the active surface so that it defines a narrow gap allows the geometry of the encapsulant front (the line of contact between the encapsulant and the active surface) can be more closely controlled. Any variation in the flowrate of encapsulant from the needle tends to cause bulges or valleys in the height of the bead and or the PCB side of the bead. The fluidic resistance generated by the gap between the barrier and the active surface means that the amount of encapsulant that flows into the gap and onto the active surface is almost constant. The reduced flow variations make the encapsulant front closely correspond to the shape of the barrier. Greater control of the encapsulant front allows the functional elements of the active surface of the die to be closer to the contact pads.
Preferably, the barrier is a profiling surface and the method further comprises the steps of:
moving the profiling surface over the active surface to flatten the bead of encapsulant.
Preferably, the method further comprises the steps of:
prior to depositing the bead of encapsulant, electrically connecting the contact pads on the die to respective conductors on the support structure with wire bonds, the wire bonds each extending in an arc from the contact pad to the conductor;
pushing on the wire bonds to collapse the arc and plastically deform the wire bond; and,
releasing the wire bonds such that plastic deformation maintain the wire bonds in a flatter profile shape.
In a further preferred form, the active surface that has functional elements, the contacts pad being formed at one edge of the active surface, the wire bond has a diameter less than 40 microns and the arc extends more than 100 microns above the active surface of the die.
Preferably, the wire bond is plastically deformed such that it extends less than 50 microns above the active surface of the die. In another preferred form, the wire bond is pushed by engagement with a blade having a rounded edge section for contacting the wire bond.
Preferably, the bead of encapsulant has a profiled surface that is flat, parallel to and spaced less than 100 microns from the active surface.
Optionally, the bead of encapsulant has a profiled surface that is flat and inclined relative to the active surface.
Preferably, the encapsulant being an epoxy material has a viscosity greater than 700 cp when uncured.
Preferably, the encapsulant is an epoxy material that is thixotropic when uncured.
Preferably, the active surface has functional elements spaced less than 260 microns from the contacts pads of the die. In a particularly preferred form, the die is an inkjet printhead IC and the functional elements are nozzles through which ink is ejected. Preferably, the printhead IC is mounted in a printer such that during use the nozzles are less than 100 microns from the paper path.
Preferably, the support structure has a chip mounting area and a conductor mounting area, the die is supported on the chip mounting area, and a plurality of electrical conductors at least partially supported on the conductor mounting area wherein, the chip mounting area is raised relative to the conductor mounting area. In a particularly preferred form, the chip mounting area is raised more than 100 microns relative to the conductor mounting area. In preferred embodiments, the support structure has a step between the chip mounting area and the conductor mounting area. In particularly preferred embodiments, the plurality of conductors are incorporated into a flexible printed circuit board (flex PCB) with a line of bond pads along an edge closest the die, the bond pads being more than 2 mm from the contacts pads on the die.
Preferably, the support structure is a liquid crystal polymer (LCP) molding.
According to a fifth aspect, the present invention provides a method of applying encapsulant to wire bonds between a die and conductors on a supporting substrate, the method comprising the steps of:
forming a bead of the encapsulant on a profiling surface;
positioning the profiling surface such that the bead contacts the die; and,
moving the profiling surface relative to the die to cover the wire bonds with the encapsulant.
Wiping the encapsulant over the wire bonds with a profiling surface provides control of the encapsulant front as well as the height of the encapsulant relative to the die. The movement of the profiling surface relative to the die can closely controlled to shape the encapsulant to a desired form. Using the example of a printhead die, the encapsulant can be shaped to present an inclined face rising from the nozzle surface to a high point over the wire bonds. This can be used by the printhead maintenance facilities to maintain contact pressure on the wiping mechanism. This is illustrated further below with reference to the drawings. However, it will be appreciated that the encapsulant can be shaped to have ridges, gutters, grooves and so on by using a particular shape of profiling surface and relative movement with the die.
Preferably, the method further comprises the steps of:
dipping the profiling surface into a reservoir of the encapsulant material to form a the bead of encapsulant material on the profiling surface.
Optionally, the profiling surface is a blade with a straight edge and the method further comprises the steps of:
orienting the blade such that the straight edge is lowest and dipping the straight edge into the encapsulant material to form the bead of encapsulant along the straight edge.
Preferably, the die has an active surface with functional elements and a plurality of contacts pad being formed along one edge for connection with the wire bonds such that the wire bonds extend in an arc from the contacts pads to each of the conductors respectively, the wire bonds having a diameter less than 40 microns and the arc extends more than 100 microns above the active surface of the die.
Preferably, the method further comprises the steps of:
prior to encapsulation, pushing on the wire bonds to collapse the arc and plastically deform the wire bonds; and,
releasing the wire bonds such that plastic deformation maintains the wire bonds in a flatter profile shape.
Preferably, the wire bond is plastically deformed such that it extends less than 50 microns above the active surface of the die. Preferably, the wire bond is pushed by engagement with a blade having a rounded edge section for contacting the wire bond.
Preferably, the encapsulant covering the wire bonds has a profiled surface that is flat, parallel to and spaced less than 100 microns from the active surface.
Preferably, the bead of encapsulant having a profiled surface that is flat and inclined relative to the active surface.
Preferably, the encapsulant being an epoxy material has a viscosity greater than 700 cp when uncured.
Preferably, the encapsulant is an epoxy material that is thixotropic when uncured. Preferably, the functional elements are spaced less than 260 microns from the contacts pads of the die. In a further preferred form, the die is an inkjet printhead IC and the functional elements are nozzles through which ink is ejected. Optionally, the printhead IC is mounted in a printer such that during use the nozzles are less than 100 microns from the paper path.
Preferably, the support structure has a chip mounting area and a conductor mounting area, the die is supported on the chip mounting area, and a plurality of electrical conductors at least partially supported on the conductor mounting area wherein, the chip mounting area is raised relative to the conductor mounting area. In a particularly preferred form, the chip mounting area is raised more than 100 microns relative to the conductor mounting area. In another preferred form, the support structure has a step between the chip mounting area and the conductor mounting area. In a preferred embodiment, the plurality of conductors are incorporated into a flexible printed circuit board (flex PCB) with a line of bond pads along an edge closest the die, the bond pads being more than 2 mm from the contacts pads on the die. In some embodiments, the support structure is a liquid crystal polymer (LCP) molding.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which:
FIG. 1 is a schematic representation of a common prior art technique for applying a bead of encapsulant to wire bonds;
FIG. 2 is a schematic representation of a die mounted to a supporting structure with a chip mounting area raised relative to the flex PCB mounting area;
FIGS. 3A , 3 B and 3 C are schematic representations of the encapsulant bead being profiled into a desired shape using a moveable blade;
FIGS. 4A to 4D are schematic representations of wire bonds being profiled by plastic deformation;
FIGS. 5A and 5B show the encapsulant bead height reductions for plastically deformed wire bonds;
FIGS. 6A to 6C show the encapsulant bead being applied to the wire bonds using the profiling blade; and,
FIGS. 7A and 7B show the profiling blade being used to control the encapsulant bead front on the surface of the die.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
FIG. 1 shows a common technique used for applying a bead encapsulant to wire bonds. A die 4 is mounted to a supporting structure 6 adjacent the edge of a flex PCB 8 (flexible printed circuit board). The die 4 has a line of contact pads 10 along one edge and the flex PCB 8 has corresponding bond pads 12 . Wire bonds 16 extend from the bond pads 10 to the bonds pads 12 . Power and data is transmitted to the die 4 via conductive traces 14 in the flex PCB 8 . This is a simplified representation of the dies mounted within many electronic devices. The printhead IC dies mounted to the LCP (liquid crystal polymer) molding to receive print data from an adjacent flex PCB, as described in U.S. Ser. No. 11/014,769 (grant U.S. Pat. No. 7,524,016) incorporated herein by cross reference, is one example of this type of die mounting arrangement. The ordinary worker will appreciate that the die may also be mounted directly to a hard PCB with traces formed thereon.
The wire bonds 16 are covered in a bead on encapsulant 2 to protect and reinforce the bonds. The encapsulant 2 is dispensed from a discharge needle 18 directly onto the wire bonds 16 . Often the encapsulant bead 2 is three separate beads—two beads of so-called ‘dam’ encapsulant 20 , and one bead of ‘fill’ encapsulant 22 . The dam encapsulant 20 has a higher viscosity than the fill encapsulant 22 , and serves to form a channel to hold the fill encapsulant bead. The height H of the bead 2 above the die 4 is usually about 500-600 microns. In most electronic devices, this does not pose a problem. However, if the die has an active surface that needs to operate in close proximity to another surface, this bead can be an obstruction.
Elevating the Die Relative to the Flex PCB
FIG. 2 shows a stepped support structure 6 that has raised the chip mounting area 26 relative to the PCB mounting area 24 (or at least the area mounting the PCB bonds pads 12 ). With the die 4 on a raised chip mounting area 26 , the arc of the wire bonds 16 are lower relative to active surface 28 of the die 4 . In fact, the end of the wire bond 16 attached to the contact pad 10 can be the apex of the arc (bearing in mind that the wire bond arc is intended to accommodate some relative movement of the die and PCB). When the wire bonds 16 are covered with encapsulant 2 , the bead has a reduced height H above the active surface 28 of the die 4 . If the bead of encapsulant 2 uses two beads of dam encapsulant 24 and a fill encapsulant 22 , the positions, volumes and viscosities of the beads need to take the step into account. Bead heights less than 100 microns are easily achievable, and with additional measures, such as wire arc collapsing and bead profiling (discussed below), bead height of less than 50 microns are possible.
With the die 4 raised above the flex PCB 8 by 410 microns, the height of the wire bonds 16 above the die is about 34 microns. With the die raised 610 microns above the flex PCB, the wire bond height is around 20 microns. Raising the die even further has shown little or no further reduction in wire bond height with a step of 710 microns having a wire bond height of around 20 microns.
Shaping the Encapsulant Bead with a Profiling Blade
FIGS. 3A to 3C show the encapsulant 2 being profiled with a profiling blade 30 . The support structure 6 is again stepped to reduce the height of the wire bonds 16 above the die 4 . Before the epoxy encapsulant 2 has cured, the profiling blade 30 moves across the die 4 and wire bonds in a predetermined path. As shown in FIG. 3B , the blade 30 displaces the top of the bead 30 to its flex PCB side to form a flat top surface 32 that is at a significantly reduced height H above the die 4 .
The encapsulant bead 2 may be a plurality of separate beads as shown in FIGS. 1 and 2 , or a single bead of one material. However, for close dimensional control of the profiled encapsulant, the encapsulant materials used should be thixotropic—that is, once deposited from the discharge needle, or profiled by the blade 30 , the material should not flow under its own weight, but rather hold its form until it cures. This requires the epoxy to have an uncured viscosity greater than about 700 cp. A suitable encapsulant is DYMAX 9001-E-v3.1 Chip Encapsulant produced by Dymax Corporation with a viscosity of approximately 800 cp when uncured. The blade 30 may be ceramic (glass) or metal and preferably about 200 microns thick.
It will be appreciated that the relative movement of the blade 30 and the die 4 can be precisely controlled. This allows the height H to be determined by the tolerance of the wire bonding process. As long as H is greater than the nominal height of the wire bond arc above the die, plus the maximum tolerance, the encapsulant 2 will cover and protect the wire bonds 16 . With this technique, the height H can be easily reduced from 500-600 microns to less than 300 microns. If the heights of the wire bond arcs are also reduced, the height H of the encapsulant bead can be less than 100 microns. The Applicant uses this technique to profile encapsulant on printhead dies down to a height of 50 microns at its lowest point. As shown in FIG. 3C , the lowest point is at the encapsulant front and the blade 30 forms an inclined face 32 in the top of the bead 2 . The inclined face is utilized by the printhead maintenance system when cleaning the paper dust and dried ink from the nozzle face. This illustrates the technique's ability to not just reduce the height of the encapsulant bead, but to form a surface that can perform functions other than just encapsulate the wire bonds. The edge profile of the blade and the path of the blade relative to the die can be configured to form a surface that has a multitude of shapes for a variety of purposes.
Plastic Deformation of the Wire Bond Arcs
FIGS. 4A to 4C show another technique for lowering the profile of wire bonds. FIG. 4A shows the die 4 connected to the flex PCB 8 via the wire bonds 16 . While the stepped support structure 6 has lowered the height of the wire bond arcs compared to a flat supporting structure, the wire bonds still have a natural tendency to bow upwards rather than downwards towards the corner of the step. The wires 16 are typically about 32 microns in diameter and have a pull force of about 3 to 5 grams force. The pull force is the tensile load necessary to break the connection to the contact pad 10 or the bond pad 12 . Given the fragility of these structures (one of the reasons encapsulant is applied), conventional wisdom is to avoid any contact between the wire bond arcs and other solid surfaces.
As shown in FIG. 4B , the arc of the wire bonds 16 can be collapsed by a wire pusher 34 . The wire pusher 34 displaces the wire bond 16 enough to elastically and plastically deform the arc. The Applicants have shown that contact with the wire pusher 34 can cause localized work hardening in the wire, but as long as the pushing force is not excessive, it does not break. The end of the wire pusher 34 is rounded to avoid stress concentration points. The wire pusher may be a stylus for engaging single wire bonds or a blade that pushes on multiple wire bonds simultaneously.
Referring now to FIG. 4C , the wire pusher 34 is retracted and the wire springs back toward its original shape to relieve the elastic deformation. However, the plastic deformation remains and the wire bond height above the die 4 is much reduced. Testing has shown that an initial wire bond loop height of 200 microns can be reduced to about 35 microns using this technique. Tests have also shown that the pull strength of the plastically deformed wires remains at about 3 to 5 grams force.
The collapse of the wire bonds is uncontrolled and leaves the wire bonds somewhat randomly deformed. However, pushing the wire bonds closer to the die provides more uniformly shaped collapsed wire bonds. The Applicant's work has shown that engaging the wires about 200 to 300 microns for the die provides the best results.
As shown in FIG. 4D , the die 4 and the flex PCB 8 are mounted to a flat support structure 6 . As discussed above, this means the original loop height of the wire bond arc is much higher—approximately 400 microns above the die 4 . Consequently, the wire has more plastic deformation when the loop is collapsed by the wire pusher. Even so, the Applicants results show that the residual loop height after pushing is about 20-50 microns.
FIGS. 5A and 5B show the collapsed wire bonds 16 covered with an encapsulant bead 2 . Even without bead profiling prior to curing, the height H of the bead above the die is much less than the bead necessary to encapsulate the original undeformed wire loops.
Applying Encapsulant with Profiling Blade
FIGS. 6A , 6 B and 6 C show the application of the encapsulant bead using the profiling blade 30 instead of a discharge needle (see FIGS. 1 and 2 ). As previously discussed, the flowrate of encapsulant from the discharge needle can vary and this gives rise to large variations on the position of the encapsulant front on the active surface of the die 4 . Consequently, any functional elements in the active surface of the die need to be sufficiently spaced from the contacts pads 10 to allow for the meandering encapsulant front.
Applying the encapsulant with the profiling blade avoids the problems caused by the flowrate fluctuations from the discharge needle. As shown in FIG. 6A , the bead of encapsulant 40 can be formed on the profiling blade 30 by simply dipping it into a reservoir of uncured encapsulant epoxy. Of course, the bead 40 may also be formed by any other convenient method, such as running the discharge needle along one end of the blade 30 .
FIG. 6B show the blade 30 having been lowered to touch the bead 40 onto the die 4 . When the encapsulant material touches the die surface, it wets and wicks along the surface while remaining pinned to the edge of the blade. The blade 30 is held at a predetermined height above the die 4 and moved over the bead 2 to flatten and lower its profile. The encapsulant displaced from the top of the bead 2 by the blade 30 , spreads over the PCB side of the bead 2 . It is not relevant if the encapsulant spreads further over the PCB than necessary. As long as the wire bonds 16 and the bonds pads 12 are covered, any additional encapsulant on the PCB 8 surface is not detrimental.
In FIG. 6C , the wire bond 16 height has been reduced by collapsing the arc in accordance with the techniques discussed above. As previously discussed, the bead 2 deposited by the discharge needle need not be as big to cover the wire bond 16 once it has been collapsed. Furthermore, the blade 30 can be brought closer to the die 4 without contacting wire bonds 16 when profiling the encapsulant 2 . Hence the bead profile in FIG. 6C is substantially lower than that of FIG. 6B .
Encapsulant Front Control
When the encapsulant material is dispensed from the discharge needle, minor variations in the flowrate can cause the bead to bulge at points of higher flow. Consequently, the side of the bead that contacts the active surface of the die is not straight, but has significant perturbations. These perturbations have to be accommodated between the contact pads and any functional elements on the active surface. The spacing between the contacts pads and the functional elements consumes valuable ‘chip real estate’. The Applicant has previously developed printhead dies with a spacing of 260 microns between the contact pads and the first row of nozzles. Better control of the encapsulant front reduces the space between the contacts and operational elements, and so the overall dimensions of the die. Hence the design can be more compact and more chips fabricated from the original wafer disc.
As shown in FIGS. 7A and 7B , the profiling blade 30 is used to control the front 36 of the bead of encapsulant 2 . The blade 30 is positioned over the die 4 to define a gap 42 between its lower edge and the active surface 28 . As the discharge needle 18 dispenses the encapsulant material 44 , it flows onto the active surface, one side of the blade and a fillet of the material extends through the gap 42 . Because of the flow restriction created by the gap, flow variations have a reduced effect on the dimensions of the fillet that flows through the gap. Therefore the encapsulant front 36 closely corresponds to the line of the lower edge of the blade 30 .
As shown in FIG. 7B , the profiling blade 30 is already in position to profile the encapsulant bead 2 once it has been dispensed from the discharge needle. The blade 30 simply moves over the die 4 in a direction away from the nozzles 38 . This keeps the encapsulant front 36 in place and flattens the profile of the encapsulant bead 2 over the wire bonds 16 .
The invention has been described herein by way of example only. The ordinary will readily recognize many variations and modifications which do not depart from the spirit and scope of the broad inventive concept.
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A method of profiling a wire bond between a contact pad on a die, and a conductor on a supporting structure, by electrically connecting the contact pad on the die to the conductor on the supporting structure with a wire bond, the wire bond extending in an arc from the contact pad to the conductor, pushing on the wire bond to collapse the arc and plastically deform the wire bond, and then releasing the wire bonds such that the plastic deformation maintains the wire bond in a flatter profile shape. The strength of the wire bond is known to be relatively small; of the order of 3 to 5 grams force. However, the Applicant's work has found that the wire bond structure is robust enough to withstand a certain degree of work hardening from plastic deformation. The arc of the wire bond can be deformed into a flatter profile without compromising the electrical connection with the PCB.
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FIELD OF THE INVENTION
This invention relates to passive temperature regulating systems generally, and more specifically to an integral roof cooling system for passively cooling the interior of a structure exposed to extreme heat and cold.
BACKGROUND OF THE INVENTION
The interior spaces of structures exposed to extreme heat are typically cooled by active refrigeration and evaporative cooling systems. Unfortunately, such systems demand a substantial amount of electric or other type of external power which generates large operating costs in addition to the initial cost of the system. Refrigeration systems use almost as much electrical energy to power fans and pumps, and require constant replenishment of their water supply.
The cost of active cooling systems is not always prohibitive in structures designed for human habitation or use, such as homes, office buildings, factories and the like. However, cooling systems are often desirable in other types of structures where the installation and operating costs of active cooling systems cannot be justified, such as relatively small or remote structures designed to house livestock or electrical or fiber-optic equipment. It is often not feasible to bring electricity to a remote structure or to provide for the generation of electricity on-site, or to provide an alternative source of power. As a result, active cooling systems often cannot be used in situations in which some form of temperature control is highly desirable.
In an attempt to solve the above problems, passive cooling systems have been developed to provide cooling by passively radiating heat to the night sky. One such system is disclosed in commonly assigned U.S. Pat. No. 5,070,933 to Baer, the complete disclosure of which is incorporated herein by reference. In this cooling system, a plurality of plastic containers filled with water and insulation are mounted to the roof of the structure. The insulation contains vertical passages so that the water may flow between the upper and lower walls of the container. During the evening, relatively cold water, chilled by the night atmosphere, flows downwardly through the vertical passages in the insulation towards the lower wall of the container and cools the interior of the structure by heat transfer. During the day, the insulation and water minimize the penetration of heat from the outside.
One problem with existing passive cooling systems such as the above referenced patent is that the plastic containers filled with water and insulation are heavy. Therefore, these systems typically include a large and relatively expensive support system to hold the plastic containers against the roof of the structure. In addition, gravity and thermal stresses eventually cause the heavy plastic containers to sag away from the roof Of the structure. This decreases the heat transfer from the water to the cool night air because the plastic containers are no longer in intimate contact with the roof.
Another problem with existing passive cooling systems is that the plastic containers will deform with severe changes in temperature. Since thermal deformation tends to have a permanent effect on plastic (plastic, unlike metals, does not have a "memory" for its original shape), the plastic containers will not completely return to their original shape after these severe temperature changes. This permanent deformation of the containers can have a detrimental effect on the heat transfer characteristics of the temperature regulating system.
SUMMARY OF THE INVENTION
The present invention is directed to a passive temperature regulating system for cooling a structure exposed to extreme heat and cold and a method of manufacturing the temperature regulator system. The invention provides a relatively inexpensive cooling system integrally formed to the roof of the structure that eliminates the need for an expensive support system and alleviates the above described problems of sagging and permanent thermal deformation.
In one aspect of the invention, the passive temperature regulating system comprises an enclosure including a roof with an uneven interior surface. At least one temperature regulator is integrally formed to the interior surface of the roof. Each temperature regulator comprises a molded container having an inner chamber and an upper surface molded to the uneven interior surface such that the upper surface substantially conforms to the interior surface thereby rigidly securing the container to the roof. A supply of water fills the chamber and is in contact with essentially the entire effective heat transfer area of the upper surface. Insulation is disposed in the chamber adjacent the upper surface with passages that allow the water to flow vertically through or around the insulation.
An important advantage of the system is that the upper surface of the container has been molded to the interior surface of the roof such that the container has become an integral part of the roof. Thus, the container will remain in intimate contact with the roof, thereby supporting its own weight and eliminating the need for an expensive support system. In addition, the uneven interior surface increases the heat transfer area between the container and the roof, thereby facilitating convection with the cool night air and radiation to the cool night sky.
The above described temperature regulator is manufactured from a mold having a lower mold portion removably attached to an upper wall section. The upper wall section has an uneven lower surface and is adapted to be part of the roof of the structure. A resinous material, such as plastic, is melted and molded to form a container that conforms to the inner surface of the lower mold portion and the uneven lower surface of the upper wall. The mold and the container are then cooled and the lower portion is removed. The container will remain fixed to the upper wall because the melted plastic has conformed to the uneven lower surface thereby integrating the container with the upper wall.
In one embodiment, the uneven lower surface includes channels extending downward from the surface so that the upper surface of the container conforms around the channels. During the rotational molding step, the melted plastic material will flow evenly around the channels and the lower surface of the upper wall. When the plastic and mold cool, the plastic will adhere to the channels so that the newly formed container is secured to the upper wall. Thus, a portion of the mold (the upper wall) becomes an integral part of the product (the container). In other embodiments, the uneven lower surface may include depressions or protrusions in this surface so that the melted plastic flows into the depressions or around the protrusions to secure the container to the upper wall.
In a preferred embodiment, a small opening is formed in the container to insert the insulation and water after the container has been molded to the upper wall. The insulation is movable between an elongated configuration, where the insulation is adapted for introduction through the small opening, and a collapsed configuration, where the insulation generally conforms to the upper surface of the container. With this configuration, a generally rectangular slab of insulation can be inserted into the plastic container without substantially removing or altering the outer walls of the container.
To minimize permanent thermal deformation of the plastic container, the temperatures regulator preferably includes elastic members, such as springs or metal reinforcement, surrounding the container. The elastic members bias the containers so that the containers will generally return to their original shape after they have been deformed by a severe temperature change, such as an extensive freeze thaw cycle.
The above is a brief description of some deficiencies in the prior art and advantages of the present invention. Other features, advantages and embodiments of the invention will be apparent to those skilled in the art from the following description, accompanying drawings and appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side cross-sectional view of the temperature regulator in accordance with the principles of the present invention;
FIG. 2A is a top view of a slab of insulation for the temperature regulator of FIG. 1;
FIG. 2B is a top view of the insulation of FIG. 2A in an expanded position for insertion into the temperature regulator of FIG. 1;
FIGS. 3A-3C are diagrammatic views illustrating a method of manufacturing the temperature regulator of FIG. 1;
FIG. 4 is a sectional view of the temperature regulating system in accordance with the principles of the present invention; and
FIG. 5 is a bottom plan view of the temperature regulating system of FIG. 4 with a portion thereof taken in partial cross-section.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings in detail, wherein like numerals indicate like elements, the temperature regulating system is illustrated according to the principles of the present invention.
As illustrated in FIG. 1, temperature regulator 2 comprises a container 4 defining an inner chamber 5 and having an upper wall 6 with an upper surface 7 molded to a lower surface 8 of a thermally conductive planar element or a wall section 10. Wall section 10 is adapted to form part of the roof of a structure and is preferably constructed of a highly conductive material, such as aluminum or steel, to facilitate heat transfer through wall 10. Container 4, on the other hand, is constructed using a material with a relatively low thermal conductivity and which is a poor conductor of heat, such as plastic (the heat transfer characteristics of wall 10 and container 4 will be discussed in greater detail below).
Lower surface 8 of wall 10 includes a plurality of protrusions or depressions to create an uneven lower surface for rigidly securing container 4 to the planar element or wall section 10. In a preferred configuration, lower surface 8 of wall 10 includes a plurality of channels 12 spaced apart from each other and extending downward into container 4. Upper surface 7 of container 4 has been molded to wall 10 so that it substantially conforms to channels 12 and lower surface 8, as shown in FIG. 1. Preferably, channels 12 will comprise the same material as wall 10 or at least the same material as lower surface 8 of wall 10. Channels 12 serve to lock the plastic container 4 to the metal wall 10 when these two parts are molded together so that upper surface 7 becomes an integral part of lower surface 8 (this method will be discussed below). Channels 12 also increase the surface area of lower surface 8 thereby increasing the effective heat transfer area between container 4 and wall 10.
It should be noted that the invention is not limited to channels 12 extending from lower surface 8. Lower surface 8 can have a variety of shapes so long as it has a generally uneven surface so that melted plastic will flow over shapes or through holes in lower surface 8 to lock the plastic to the metal wall 10 (discussed below). For example, lower surface 8 could have a series of depressions, protrusions such as ridges, fins or bumps, or a combination of these features.
Container 4 houses water 20, the thermal mass of the regulator, and insulation 22 suspended in the upper region of container 4. The water 20 absorbs and transfers heat from the system (described below). Container 4 further includes a port 24 which permits container 4 to be filled with or drained of water 20. Port 24 also provides a way in which to introduce insulation 22 into container 4, as described in further detail below. Port 24 can be sealed with a plug 26 or with other sealing means conventionally known in the art, so that the water 20 is retained in container 4.
Insulation 22 is preferably a single slab buoyant enough to float near the upper region of container 4. Insulation 22 is movable between a collapsed configuration (FIG. 2A), where insulation 22 generally conforms to the shape of the upper region of container 4, and an elongated configuration (FIG. 2B), where insulation 22 is configured for introduction through port 24. As shown in FIG. 2A, insulation 22 has a longitudinal axis 26 and first and second ends 28, 30 on opposite sides of axis 26. A series of lateral cuts 32 have been formed in insulation 22 from one end to a point 34 proximate the opposite end. Lateral cuts 32 extend completely through insulation 22 so that insulation 22 can be extended into the Z configuration shown in Fib. 2B. To position insulation 22 within container, a distal tip 36 of insulation is introduced through port 24 and the rest of insulation 22 guided through port 24 into container 4. With this configuration, insulation 22 can be positioned within container 4 without substantially removing or altering one of the outer walls of container 4.
Insulation 22 is preferably constructed of a resilient material so that insulation 22 is naturally biased into the collapsed configuration of FIG. 2A. Preferably, this configuration is generally rectangular so that insulation 22, after being completely introduced through port 24 of container 4, will reassemble into the collapsed configuration to conform to the effective heat transfer area of wall section 10. It will be noted, however, that insulation 22 is not limited to a single slab of material. For example, insulation 22 could comprise a plurality of smaller elements such as hollow plastic or foam spheres, as disclosed in U.S. Pat. No. 5,070,933 to Baer, which has been incorporated herein by reference.
Referring again to FIG. 1, insulation 22 has an upper surface 40 with vertical projections 42 so that a space or gap 44 is formed between insulation 22 and lower surface 46 of upper wall 6 of container 4. Otherwise, the buoyancy of insulation 22 would cause its upper surface 40 to come into contact with upper wall 6 of container 4, displace the water 20 therebetween, and seriously impede heat transfer from wall section 10 to the thermal mass of temperature regulator 2. Note that channels 12 may be also used to form gap 44 because they extend downward from wall 10. However, vertical projection 42 may be necessary if wall 10 contains depressions or extremely small protrusion instead of channels 12, as discussed above.
Insulation 22 also includes vertical passages 48 that permit water 20 in container 4 to flow from the region below insulation 22 to gap 44. As discussed below, warmer water will tend to rise through vertical passages 46 thereby displacing cooler water in the upper region of chamber 5.
Container 4 has been molded into a generally rectangular shape having outer walls 50 with an outer contour. However, severe temperature changes, such as a long cold spell followed by a warmer period, may cause the plastic container 4 to deform so that outer walls 50 lose their original shape or contour. To alleviate this problem, springs (not shown) may be disposed outside of chamber 5 to bias container 4 so that outer walls 50 return to their original shape after being thermally deformed by temperature changes. Alternatively, outer walls 50 of container 5 may have a metal reinforcement (not shown) so that the walls will behave similarly to metals (i.e. retaining a "memory" of their original shape so that thermal deformation is only temporary).
Referring to FIGS. 3A-3C, the method for manufacturing temperature regulator 2 in accordance with the present invention will now be described. Container 4 is preferably formed by rotationally molding a resinous material such as plastic within a mold 60. Of course, the invention is not limited to the rotational molding technique that will be described below. For example, container 4 could be manufactured by blow molding, injection molding or other conventional techniques.
Referring to FIG. 3A, mold 60 comprises wall section 10 (i.e. a section of the roof of the structure) and a lower mold portion 62 having an inner surface 64 surrounding a mold cavity 66. Channels 12 extend from wall section 10 into mold cavity 66. Lower mold portion 62 is preferably constructed of metal, such as aluminum or steel, and is removably attached to wall 10 by conventional means, such as clamps, screws or rivets. Inner surface 64 will preferably be as smooth as possible to facilitate the separation of container 4 (shown in FIG. 3C) from lower mold portion 62 after container 4 has been formed.
To rotationally mold container 4, the plastic, generally in the form of pellets (not shown), is placed within mold cavity 66. Mold 60 is then attached to the arm of a rotational molding machine (not shown) and transferred to an oven (also not shown). The oven heats mold 60, thereby melting the plastic while the rotational molding machine simultaneously rotates mold 60 about two axes in a conventional manner. The melted plastic will tend to flow to the lowest point in mold cavity 66 as the mold 60 is biaxially rotated, thereby completely covering inner surface 64 of lower mold portion 62 and lower surface 8 and channels 12 of wall 10.
As shown in FIG. 3B, after the inner surfaces of mold 60 are uniformly coated, the mold 60 is cooled so that the plastic hardens into container 4. After the mold 60 is cooled, lower mold portion 62 is removed from container 4 and wall 10, as shown in FIG. 3C. Note that lower mold portion 62 can easily be removed from the hardened plastic because inner surface 64 is relatively smooth. However, wall 10 remains fixed to container 4 because the melted plastic conforms to channels 12 so that the plastic locks to the metal, thereby integrating wall 10 with upper surface 6 of container 4.
After lower mold portion 62 has been removed, port 24 is formed in container 4 by conventional means. Insulation 22 is then stretched into the elongated configuration of FIG. 2B and introduced through port 24. Once insulation 22 is completely within container 4, it will naturally spring back into the collapsed position of FIG. 2A to substantially conform to the effective heat transfer area of upper surface 6. Container 4 is then partially filled with water 20 and port 24 is resealed by conventional means.
Referring to FIGS. 4 and 5, a plurality of regulators 2 are shown as being secured to a roof 70 of a storage room or enclosure 72 to regulate the temperature of the interior space 74 of enclosure 72. Roof 70 is formed of a plurality of wall sections 10 that have been molded to containers 4, as discussed above. Containers 4 are integrated to wall sections 10 and, therefore, will remain in intimate contact with roof 70 to provide an effective heat transfer surface therebetween.
The temperature regulating system operates by disposing heat during the night, slowly warming during the day, and then cooling again after sundown. During the day, when roof 70 is heated by solar radiation, insulation 22 and water 20 within containers 4 provide a substantial barrier to the transfer of heat into the structure. At night, the radiation of heat from the roof 70 into the night sky cools water 20 above insulation 22 so that it becomes cooler than water 20 below insulation 22. Since warmer water tends to rise, the warmer water will circulate upwardly through vertical passages 48 in insulation 22 so that the entire water mass is cooled by a combination of convection and radiation to the night sky. A complete description of this heat transfer process is described in commonly assigned U.S. Pat. No. 5,070,933 to Baer.
The above is a detailed description of various embodiments of the invention. It is recognized that departures from the disclosed embodiments may be made within the scope of the invention and obvious modifications will occur to a person skilled in the art. The full scope of the invention is set out in the claims that follow and their equivalents. Accordingly, the claims and specification should not be construed to unduly narrow the full scope of protection to which the invention is entitled.
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A passive temperature regulating system for cooling a structure exposed to extreme heat and a method for manufacturing the temperature regulator system. The system comprises at least one temperature regulator integrally formed to the roof of the structure. The temperature regulator is manufactured from a mold having a lower mold portion removably attached to an upper wall. The upper wall has an uneven lower surface and is adapted to be part of the roof. A resinous material is molded within the mold to form a container. After cooling, the lower portion is removed and the container remains an integral part of the upper wall because the melted plastic has conformed to the uneven lower surface of the upper wall. Thus, the container will remain in intimate contact with the roof, thereby supporting it own weight and eliminating the need for an expensive support system.
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RELATED APPLICATION
[0001] This application is the full utility filing of U.S. provisional application No. 60/447,646 filed on Feb. 14, 2003, from which the present application claims priority and which is incorporated herein by reference.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0002] This patent application is related to the following Provisional patent applications filed in the U.S. Patent and Trademark Office, the disclosures of which are expressly incorporated herein by reference:
U.S. Patent Application Ser. No. 60/446,617 filed on Feb. 11, 2003 and entitled “System for Coordination of Multi Beam Transit Radio Links for a Distributed Wireless Access System” [15741] U.S. Patent Application Ser. No. 60/446,618 filed on Feb. 11, 2003 and entitled “Rendezvous Coordination of Beamed Transit Radio Links for a Distributed Multi-Hop Wireless Access System” [15743] U.S. Patent Application Ser. No. 60/446,619 filed on Feb. 12, 2003 and entitled “Distributed Multi-Beam Wireless System Capable of Node Discovery, Rediscovery and Interference Mitigation” [15742] U.S. Patent Application Ser. No. 60/447,527 filed on Feb. 14, 2003 and entitled “Cylindrical Multibeam Planar Antenna Structure and Method of Fabrication” [15907] U.S. Patent Application Ser. No. 60/447,643 filed on Feb. 14, 2003 and entitled “An Omni-Directional Antenna” [15908] U.S. Patent Application Ser. No. 60/447,644 filed on Feb. 14, 2003 and entitled “Antenna Diversity” [15913] U.S. Patent Application Ser. No. 60/447,645 filed on Feb. 14, 2003 and entitled “Wireless Antennas, Networks, Methods, Software, and Services” [15912] U.S. Patent Application Ser. No. 60/451,897 filed on Mar. 4, 2003 and entitled “Offsetting Patch Antennas on an Omni-Directional Multi-Facetted Array to allow Space for an Interconnection Board” [15958] U.S. Patent Application Ser. No. 60/453,011 filed on Mar. 7, 2003 and entitled “Method to Enhance Link Range in a Distributed Multi-hop Wireless Network using Self-Configurable Antenna” [15946] U.S. Patent Application Ser. No. 60/453,840 filed on Mar. 11, 2003 and entitled “Operation and Control of a High Gain Phased Array Antenna in a Distributed Wireless Network” [15950] U.S. Patent Application Ser. No. 60/454,715 filed on Mar. 15, 2003 and entitled “Directive Antenna System in a Distributed Wireless Network” [15952] U.S. Patent Application Ser. No. 60/461,344 filed on Apr. 9, 2003 and entitled “Method of Assessing Indoor-Outdoor Location of Wireless Access Node” [15953] U.S. Patent Application Ser. No. 60/461,579 filed on Apr. 9, 2003 and entitled “Minimisation of Radio Resource Usage in Multi-Hop Networks with Multiple Routings” [15930] U.S. Patent Application Ser. No. 60/464,844 filed on Apr. 23, 2003 and entitled “Improving IP QoS though Host-Based Constrained Routing in Mobile Environments” [15807] U.S. Patent Application Ser. No. 60/467,432 filed on May 2, 2003 and entitled “A Method for Path Discovery and Selection in Ad Hoc Wireless Networks” [15951] U.S. Patent Application Ser. No. 60/468,456 filed on May 7, 2003 and entitled “A Method for the Self-Selection of Radio Frequency Channels to Reduce Co-Channel and Adjacent Channel Interference in a Wireless Distributed Network” [16101] U.S. Patent Application Ser. No. 60/480,599 filed on Jun. 20, 2003 and entitled “Channel Selection” [16146]
FIELD OF THE INVENTION
[0020] This invention relates to methods and apparatus for wireless communication. The invention relates particularly, although not exclusively, to a wireless relay network.
BACKGROUND TO THE INVENTION
[0021] Wireless Community Area Networks (CANs) have been developed to provide access to the internet for wirelessly-enabled users. A CAN is a network with a size lying between a Wireless Local Area Network (LAN) and a Wide Area Network (WAN). Thus a CAN may provide network access to users distributed over, say, a 1 km 2 area, such as a town centre or a university campus. A schematic diagram of a CAN is shown in FIG. 1 .
[0022] The link 14 from the CAN to the user 12 often uses a cheap and widely-available wireless standard, such as IEEE 802.11 set of protocols, often referred to for simplicity as ‘WiFi’.
[0023] Current CAN implementations, such as those installed at some US university campuses (for example Carnegie Mellon University), use off-the-shelf WiFi Access Points (APs) 10 , connected to each other and to the broadband backbone 16 (and ultimately the internet) across a set of links 18 which is termed a ‘Distribution System’ (DS). This DS ‘backhaul’ link usually uses a wired interface, most commonly based on IEEE 802.3 or ‘Ethernet’.
[0024] A wired DS is desirable from the point of view that it offers a reliable high-bandwidth/low latency path for onward transmission of data. However, the problem with this wired approach is that wires of communications quality need to be provided to each AP, and interconnected via wired switches/hubs/routers etc. In some environments, such as company or university campuses, this wired infrastructure may already be in place. However, in other environments the installation and maintenance of this wired backhaul infrastructure could be prohibitively expensive.
OBJECT TO THE INVENTION
[0025] The invention seeks to provide a method and apparatus for wireless communication which mitigates at least one of the problems of known methods.
SUMMARY OF THE INVENTION
[0026] According to a first aspect of the invention there is provided a method of synchronising transmission between two nodes in a wireless network, said method comprising the steps of obtaining an expected interference profile for each node; and agreeing a synchronised transmission schedule between the nodes, where the expected interference profile of the or each node meets predetermined criteria.
[0027] Preferably, the expected interference profile is obtained by detecting interference received at each node.
[0028] The interference profile may be characterised according to transmission parameters, which may include time and frequency.
[0029] Each node may comprise a multiple beam antenna, and said transmission parameters may further include the selected beam.
[0030] According to a second aspect of the invention there is provided a node in a wireless network comprising: a memory for storing an expected interference profile of the node; a processor for determining where the expected interference profile of the node meets predetermined criteria; and a transceiver for communicating with a second node to agree a synchronised transmission schedule according to the determination of the processor.
[0031] According to a third aspect of the invention there is provided wireless network comprising a plurality of nodes as described above.
[0032] According to a fourth aspect of the invention there is provided a method of communication between two nodes in a wireless network, said method comprising the steps of: Obtaining an expected interference profile for each node; Agreeing a synchronised transmission schedule between the nodes, where the expected interference profile of the or each node meets predetermined criteria; and Effecting communication in accordance with the synchronised transmission schedule.
[0033] According to a fifth aspect of the invention there is provided a signal for agreeing a synchronised transmission schedule between a first and a second node, said signal comprising a reference to a transmission slot, where the expected interference profile at a node meets predetermined criteria.
[0034] Advantageously, use of a wireless Distribution System (DS) avoids the high installation and maintenance costs of a wired DS.
[0035] Use of synchronised Transit Link Control allows the nodes to schedule their transmissions such that they can avoid interference to and from each other. It enables distant nodes to effectively coordinate their transmissions for the purposes of eliminating mutual interference without needing explicitly to communicate directly with each other.
[0036] Additionally, it enables nodes to schedule their transmissions such that they can avoid interference from non-system interferers.
[0037] By dividing up the transmission bandwidth into a number of slots according to a selection of transmission parameters, it provides a greater opportunity for nodes to find a transmission slot which is suitable for use.
[0038] Utilisation of the multiple degrees of freedom of wireless communication, (e.g. beam, frequency, polarisation, burst time) mitigates interference and maximises system capacity.
[0039] Advantageously, this invention enables the sharing of carrier frequencies within a wireless network using unspoken coordination.
[0040] Use of directivity within a Transit Node improves reach and minimises interference.
[0041] The method may be performed by software in machine readable form on a storage medium.
[0042] The preferred features may be combined as appropriate, as would be apparent to a skilled person, and may be combined with any of the aspects of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0043] An embodiment of the invention will now be described with reference to the accompanying drawings in which:
[0044] FIG. 1 is a schematic diagram of a Community Area Network (Prior Art);
[0045] FIG. 2 is a schematic diagram of a Community Area Network according to the present invention;
[0046] FIG. 3 is a schematic diagram of an installed Wireless Access and Routing Point (WARP) according to the present invention;
[0047] FIG. 4 is a schematic diagram of an example of a beam pattern of a WARP according to the present invention;
[0048] FIG. 5 shows an example of an Interference Table according to the present invention; and
[0049] FIG. 6 shows an example of a typical traffic loading for a 6 hop, 21 WARP tree structure network according to the present invention.
DETAILED DESCRIPTION OF INVENTION
[0050] Embodiments of the present invention are described below by way of example only. These examples represent the best ways of putting the invention into practice that are currently known to the Applicant although they are not the only ways in which this could be achieved.
[0051] Referring to FIGS. 2-6 , there is shown an example of the present invention.
[0052] FIG. 2 shows a schematic diagram of a CAN. The network comprises a number of Wireless Access and Routing Points (WARPs) 20 , interconnected by wireless links 22 . This CAN therefore uses a wireless ‘Distribution System’ (DS). The WARPs perform a number of functions, including acting as access points (APs) for connection to mobile nodes (MNs) such as PDAs. The area of coverage of the access link (AL), which is the link from the AP to a MN is shown schematically in FIG. 2 by the circles 26 . The WARPs are wirelessly connected to each other and to the Network Access Point (NAP) 24 . The WARPs also act as Transit Nodes (TNodes), for wirelessly relaying information between WARPs and also between a WARP and a NAP. The NAP itself connects into a wired/fibre broadband backbone, which in turn is likely to be connected to the internet. A wireless link 22 (also referred to as a backhaul link) from one WARP (or TNode) to another, or between a WARP and a NAP is termed a Transit Link (TL), and the collection of TNodes and Transit Links is referred to as a ‘Transit Network’ (or TNet). The CAN is used to transmit packets of data and has the ability to forward packets towards their destination by hopping over wireless links through intermediate WARPs (acting as TNodes). FIG. 2 shows a single NAP within the CAN. However, in general there may be more than one NAP within the network.
[0053] The CAN shown in FIG. 2 uses wireless technology both for connection to mobile terminals (over the ‘Access Link’) and for backhaul to a broadband access point (in the wired network).
[0054] The CAN shown in FIG. 2 is in a mesh configuration. This is not the only possible configuration. Other configurations, such as a tree structure, may be more suitable for some networks.
[0055] FIG. 3 shows a schematic diagram of an installed WARP. The WARP 30 may be fixed to a lamp post, utility pole, wall or other elevated mounting position 32 . The WARP provides an Access Link 34 to mobile nodes (MNs) 36 and a Transit Link 38 to other WARPs or to a NAP (as shown in FIG. 1 ). The Transit Link and the Access Link may use different wireless technologies. For example the Transit Link may use 802.11a technology to provide a 5 GHz link and the Access Link may use 802.11b technology to provide a 2.4 GHz link. The coverage of the two links will not be the same, as shown in FIG. 2 , with the Access Link providing local coverage 39 and the Transit Link operating over larger distances so as to communicate with other WARPs or NAPs.
[0056] In a preferred embodiment, the antenna on the WARP for the Transit Link may be a switched beam antenna and a schematic diagram of such a beam pattern is shown in FIG. 4 . The pattern comprises a number of overlapping beams and eight such beams are shown 41 - 48 . The number of beams is not fixed at eight and there may be more beams or fewer beams. The WARP may have only one radio for the Transit Link, which means that it can only transmit on one beam at any one time. This is beneficial as it reduces the cost of the WARP. Other antenna array processing techniques such as transmit diversity and receive diversity may also be beneficial.
[0057] In order to operate the Transit Network, a protocol is used which operates at a higher layer than the protocol which is used on the Transit Links (for example 802.11a) and at a lower layer than the routing protocol. This intermediate layer is referred to as the Transit Link Control (TLC) layer. The TLC layer is responsible for scheduling TL transmissions on certain carrier frequencies, beams, time slots etc. This invention relates to a Synchronous Transit Link Control (S-TLC) layer. An alternative technique using an asynchronous approach is described in a co-pending U.S. patent application.
[0058] For control purposes and to improve efficiency and accessibility, the transmission bandwidth on the Transit Links is divided up into transmission slots according to various transmission parameters. The transmission parameters may include time, frequency, beam, polarisation and any other suitable independent parameter. By this means the transmission space is divided up into a multi-dimensional array of possible transmission slots. The length of the transmission slots (or time slots) can be chosen according to the network requirements and the accuracy of the clocks used. A long time slot may be beneficial in some cases as it requires a lower accuracy clock within the network nodes and a shorter time slot may be beneficial in some cases as it reduces the delay before a signal can be sent (because the time to the start of the next slot is reduced). The term ‘network node’ is used to refer to any node within the Transit Network, including but not limited to WARPs and NAPs.
[0059] For S-TLC the clocks within the network nodes must be aligned. The clocks may be exactly synchronised, (i.e. slot 1 is the same for all nodes) or alternatively time slot boundaries may be synchronised although not absolute slot numbers (e.g. slot 1 on node 1 may correspond to slot 10 on node 2 but both slots start at the same time).
[0060] There are a number of techniques for aligning the clocks within the network nodes and two techniques are described here:
[0061] 1. Use of GPS (Global Positioning System): By incorporating a GPS receiver into each node, each node will be synchronised to the central GPS clock.
[0062] 2. Distribution of time stamped packets: Data packets including time stamps are distributed between nodes and each node aligns its clock with any time stamp received from a faster running clock. This may be implemented using the 802.11a Beacon Frame structure which already includes a time stamping function.
[0063] A second element of S-TLC is that each node has an Interference Table, as shown in FIG. 5 . An interference table is a historical record of which slots within the multi-dimensional array of transmission slots (described above) have tended to suffer from interference. The interference table therefore gives an indication of the expected interference in a given transmission slot. The interference table may be supplied to the node, but preferably the table is independently created and maintained by each node within the network. Methods of measuring interference are well known in the art. The interference table is created and maintained by periodically monitoring the received interference levels and updating the table accordingly.
[0064] An example interference table is shown in FIG. 5 . It is a three-dimensional array using the following parameters:
[0065] Beams, 50 : 1-8 (although only data for beams 1, 2 and 8 shown)
[0066] Time slots, 51 : 1-20
[0067] Carrier frequencies, 52 : 1-8
[0068] These three parameters have been selected by way of example only. Any number of suitable transmission parameters can be used. Suitable parameters include, but are not limited to, beams, time slots, carrier frequencies and polarisation.
[0069] In preparing an interference table, a repeat cycle must be selected, (e.g. 100 ms in this case, with this time being divided into 20 slots). This repeat cycle must be the same throughout the network. The table shows the particular time slots on particular frequencies of each beam that should not be used for transmission as historically they have suffered from interference. The interference sources may be transmissions from other nodes within the network (as shown at 53 ) or sources outside the network (as shown at 54 ). The non-network interferer, which may be a nearby wireless LAN, may mean that a single frequency cannot be used at all for a particular beam. Preferably the interference table is be compiled from averages of interference received over many repeat cycles. It is anticipated that interference tables will remain the same for periods of tens of minutes or longer.
[0070] It should be noted that each node may have a different interference table due to local interference effects. It is not necessary for a node to know the source of the interference it detects and records in its interference table. The node only needs to know that interference is present in order to avoid transmitting in the same slot. The consequences of transmitting in a slot where there is interference include:
i). A packet transmission is deferred (due to sensing of the medium, and backoff, in the underlying Medium Access Control layer) ii). A packet is lost, because the interference was too high at the receiver iii). The packet was successfully sent, but at a lower data rate than would otherwise have been possible in the absence of the interference
[0074] All of these three outcomes listed are undesirable and should be avoided if possible. Whilst a Synchronous TLC cannot totally guarantee that interference will be eliminated for each TL packet exchange, it can nevertheless significantly reduce the probability of such interference occurring. It does this by enabling distant TNodes effectively to coordinate their transmissions for the purposes of eliminating mutual interference without needing explicitly to communicate directly with each other for this purpose (the nodes may communicate directly with each other for different purposes, such as authentication and routing).
[0075] As each node has its own interference table, it is necessary for adjacent nodes to agree some scheduled blots (referred to herein as ‘skeds’) for transmission of packet data between them according to when both nodes have suitable slots within their interference tables. A suitable slot is defined as one which meets preset criteria. These criteria will preferably relate to the level of expected interference as determined from the interference table and an acceptable expected interference threshold may be defined. As each node may only have a single radio for transmitting over a Transit Link, it will also be necessary for each node to ensure that they also are capable of transmitting in that slot, (if there is only one radio, the node cannot transmit to more than one node at any one time). The scheduling of initial slots may be established on start up and subsequent slots may be negotiated during already agreed slots.
[0076] The scheduling of transmission slots may be for the purpose of setting up a new transmission link or for increasing the bandwidth of an already existing link. Scheduled slots may be agreed by an initiating node signalling to the proposed recipient with a proposal of a slot for a scheduled transmission. The recipient, referring to its own interference table, may refuse the slot or accept the slot. On refusal of the slot the system may be established such that the initiating node or the recipient node proposes a new slot. The process can then be repeated until a mutually convenient slot is found.
[0077] A transceiver may be used to communicate to agree the scheduling of slots. The term transceiver is used herein to mean any apparatus capable of transmitting and/or receiving information.
[0078] In the situation where clocks are aligned such that their time slot boundaries are coincident but where the time slot numbers are not necessarily identical, it will be necessary for the nodes to confirm their respective slot numbering schemes during the negotiation for a transmission schedule (or skeds).
[0079] It is probable that any Transit Link will consist of multiple scheduled transmission slots. In the situation with a multiple beam antenna, these slots are all likely to use the same beam; however they may use different frequencies or other parameters. A node should not set up multiple transmission slots which greatly exceed the amount of data that is likely to require forwarding, because this is likely to cause interference variability to distant nodes. Interference variability may be reduced by filling up unused slots with messaging or dummy data. Nodes should therefore take a long term view when establishing a transmission schedule with another node.
[0080] As described above, nodes should preferably monitor received interference levels and update their interference tables accordingly. Additionally, in a preferred embodiment, nodes should also monitor when packets continually failed to be acknowledged during their regular scheduled transmissions (which have already been set up). When this occurs, the problematic scheduled transmission slot should be dropped and a new one established.
[0081] FIG. 2 shows a CAN having a mesh structure. This structure is not the only possible structure and one possible alternative is a tree structure. If all or most of the network traffic is expected to pass from the originating WARP, where the data was received via the Access Link from a MN, to the broadband network via the NAP, then a tree structure may be more suitable.
[0082] FIG. 6 shows a typical traffic loading for a 6 hop, 21 WARP tree structure with traffic flow from the originating WARP to the NAP, via other WARPs as required. The traffic loading at the extremities of the tree structure, WARPs A to F is very low with only 1 in 21 time slots being utilised. Closer to the NAP, the traffic loading increases until at WARP X, all 21 in 21 time slots are utilised. In this network structure a problem may arise in the delay between data arriving at an originating node A-E and being transmitted onwards to the next WARP G-L. If data arrives from a MN via the AL at WARP A in time slot 1 , and the next scheduled transmission to WARP G is not until time slot 21 , it will be necessary to wait for 20 time slots to pass before the data can pass to WARP G. In order to mitigate this concern, WARP A and WARP G may negotiate two (or more) transmission slots between themselves on the understanding that data is transmitted in any one of these slots. In order that the interference tables throughout the network are not affected by the lack of transmission in the remainder of these slots (this is the effect of interference variability as described above), WARPs A and G may transmit dummy information (plus other signalling information etc) during the slots in which there is no data to send.
[0083] Although the above description describes implementation using 802.11 wireless technology, this is not the only suitable technology. Any other wireless technology could be used instead. Use of a widely available wireless standard (such as 802.11) may provide additional benefits from design and manufacturing economies of scale.
[0084] It will be understood that the above description of a preferred embodiment is given by way of example only and that various modifications may be made by those skilled in the art without departing from the spirit and scope of the invention.
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The invention is directed to a method of synchronising transmission between two nodes in a wireless network. The method comprises the steps of obtaining an expected interference profile for each node; and agreeing a synchronised transmission schedule between the nodes, where the expected interference profile of the or each node meets predetermined criteria.
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The invention described herein was made in the course of work under a grant or award from the Department of Health, Education and Welfare.
CROSS REFERENCE TO RELATED APPLICATION
This is a continuation-in-part of Ser. No. 113,414 filed Jan. 18, 1980 (now abandoned).
BACKGROUND
This invention relates to a diagnostic test device for fecal occult blood utilizing guaiac as the test indicator. More particularly, this invention relates to a test matrix such as paper impregnated with guaiac together with a combination of substances which according to the invention prevent false-positive results in the presence of peroxidases.
A sensitive, specific and simple laboratory test for colorectal cancer is helpful in screening patients for early neoplastic lesions.
A test already available is the Hemoccult slide test for occult blood in stool (see U.S. Pat. No. 3,996,006). This simple, inexpensive laboratory test is capable of detecting blood in stool that may be related to an early cancerous lesion of the gastrointestinal tract. The test rationale which uses guaiacimpregnated paper as a test matrix is based on the phenolic oxidation of guaiac by hemoglobin in the presence of hydrogen peroxide. The production of a blue color on the test paper usually indicates the presence of blood. However, there is a 4 to 6% false positive reaction (i.e., positive test reaction without disease) as a result of non-hemoglobin interfering compounds present in the stool. It has been found that these interfering compounds are peroxidases ubiquitous to bacterial flora in the gut and in certain food sources. Each false-positive test may result in an exhaustive clinical investigation that is costly to the patient and time consuming for the physician. Aside the waste of money and manpower, the patient may be subjected to tremendous anxiety as the presence of blood in the feces may be an indication of cancer or other serious maladies.
In order to reduce the incident of interference by peroxidase in the guaiac test procedure for hemoglobin, it is a usual practice to prohibit a patient from eating vegetable products that contain peroxidase, e.g., potato, cabbage, onions, horseradish, etc. for several days. This gives time for possible interfering substances to be cleared from the body. However, indigenously present perioxidase (bacterial peroxidase) may still interfere with the test. Also patients may inadvertantly or otherwise ingest interfering substance containing vegetables notwithstanding instructions to avoid them.
The reaction of hemoglobin in fetal occult blood with guaiac in the presence of hydrogen peroxide, to give a blue color, is a known method for detection of the presence of blood as discussed above. This reaction takes advantage of the peroxidase activity of hemoglobin, which is similar to the reaction of peroxidase enzymes except that the peroxidase enzyme reaction is due to biochemical enzymatic activity while hemoglobin is not an enzyme. It is the recognition that peroxidase reacts with guaiac through enzymatic action while hemoglobin does not, that forms the basis of the present invention. By at least partially denaturing the protein that forms the peroxidase enzyme and removing the calcium and magnesium ions necessary for efficient peroxidase enzyme activity from the reaction mixture, one can eliminate the interfering effect of the peroxidase without practically affecting the hemoglobin.
It is therefor an object to avoid the problems inherent in prior art techniques by deactivating interfering peroxidase that may be present.
SUMMARY
The present invention provides an improvement in the diagnostic test technique for fecal occult blood which employs the reaction of guaiac with hemoglobin in the presence of peroxide to indicate the presence of hemoglobin by preventing false positive results. The improvement for preventing false-positive results in the presence of peroxidases comprises deactivating the peroxidase enzyme and removing the calcium and magnesium ions necessary for its efficient biochemical activity. This is preferably accomplished by cleaving the hydrogen bonds in the protein that forms the peroxidase enzyme thereby denaturing the peroxidase enzyme; and binding the calcium and/or magnesium ions with a chelating agent thereby reducing the efficiency of biochemical activity of the enzyme.
BRIEF DESCRIPTION OF THE DRAWING
The present invention will be more fully understood from the following description taken in conjunction with the accompanying drawing wherein:
FIG. 1 is a graph charting intensity against time in connection with 3:1 mixtures of turnip peroxidase in whole blood;
FIG. 2 is a graph charting intensity against time in connection with 1:1 mixtures of turnip peroxidase in whole blood; and
FIG. 3 is a graph charting intensity against time in connection with 1:3 mixtures of turnip peroxidase in whole blood.
DESCRIPTION
The thrust of the present invention is the neutralization of the effect of peroxidase enzymes on the fecal occult blood test based on a color reaction of hemoglobin with guaiac in the presence of peroxide. This is in contradistinction to the usual procedure whereby mainly through dietary restrictions, it is attempted to eliminate the peroxidases from the sample.
In the presently preferred embodiments of the invention, the effect of peroxidase enzymes is neutralized by a combination of at least partially denaturing the enzyme proteins; and effectively removing the metal ions (calcium and magnesium) from the reaction mixture which the enzyme requires for efficient biochemical activity. The effective removal of the metal ions, which can be accomplished without physical removal by use of complexing agents, avoids the need for complete denaturization of the enzyme. Thus milder methods, unlikely to greatly effect any hemoglobin that may be present, can be used. Normal color development with hydrogen peroxide is thereafter accomplished.
Heating to about 100° C. and the use of strong acids are examples of two possible denaturing methods for the enzyme protein. These are not preferred, however, as heating feces results in obnoxious smells and both heating and the use of strong acids can cause damage to any hemoglobin present. The most preferred denaturing method is the use of an effective amount of a compound that will cleave hydrogen bonds in the protein that forms the peroxidase enzyme. This will at least partially attenuate biochemical activity of the enzyme. The effective removal of calcium and magnesium ions from the reaction by complexing with a chelating agent further attenuates the biochemical activity of the enzyme to a point where, for practical purposes, the interfering effect of the peroxidase is eliminated. This combination of steps allows the use of moderate amounts of reagents and mild conditions to avoid effect on the hemoglobin to be tested.
Guaiac containing test matrices suitable for the practice of the fecal occult blood determination tests of the type over which the present invention is an improvement are known. One such device, a guaiac impregnated paper, is sold under the trademark Hemoccult and described in U.S. Pat. No. 3,996,006 referred to hereinabove. It is contemplated in the preferred embodiments hereof that the materials for neutralizing the effect of the peroxidase can be used in conjunction with known test matrices and may be applied to the test matrix either before or after the test sample is applied. For ease of application, the compunds are dissolved in a suitable solvent, most usually water, and aliquoted amounts applied to the test matrix.
Suitable compounds for at least partially denaturing the enzyme protein by cleaving hydrogen bonds include the soluble (water) salts of guanidine, urea and salicylic acid. The preferred compound is guanidine hydrochloride. As noted above, heating or the use of strong acids has possible undesirable side effects that are difficult or impossible to control.
Chelating agents that have been found suitable to sufficiently remove the metal ions necessary for effective enzyme action include ethylenediamine tetraacetic acid (EDTA) and ethyleneglycol tetraacetic acid (EGTA).
Effective amounts of the compound and chelating agent are utilized in the guaiac containing test matrix. For example, a 3 to 6 molar solution of guanidine hydrochloride in water can be used with a 10-100 millimolar solution of EDTA in water. These two solutions are combined in equal volume to form a test reagent solution and then added in an aliquot portion to the guaiac test matrix. If the test reagent solution is added before the test sample, the water can be removed so that the test matrix can be stored for receipt of a test sample at a subsequent time and location (e.g. for a doctor's office or hospital use). Alternatively, a test matrix to which a sample has already been applied can subsequently have the test reagent solution added. In either case, after a suitable reaction period, the test can proceed in a usual manner with the development of possible color using hydrogen peroxide.
At concentrations lower than about 3 moles/l, guanidine hydrochloride shows no effect while in concentrations at about 6 moles, guanidine hydrochloride undesirably crystallizes out on paper when the test matrix used is guanidine impregnated paper. In concentrations below 10 millimolar for EDTA, the desirable results in the invention are not shown and at concentrations at above 100 millimoles/l for EDTA, there is no demonstrated increase in effect.
A preferred embodiment of the invention involves the use of guaiac impregnated paper such as the Hemoccult slide to which is added EDTA and guanidine hydrochloride such that the guaiac impregnated paper contains 0.25 millimoles of EDTA and 0.15 millimoles of guanidine hydrochloride. This can be accomplished by combining equal solutions of 3 molar guanidine hydrochloride and a 100 millimolar solution of EDTA and depositing the 25 microliters of the combined solution on the Hemoccult slide.
Where the test solution is to be added to the paper before the sample, the solution containing guanidine hydrochloride and EDTA can be simply combined with the guaiac test matrix in the case where guaiac is in a liquid test matrix, or it can be sprayed or rolled on to a guaiac impregnated paper in the instance where the test matrix is paper. If added after the test sample, the test solution will necessarily be sprayed or dropped onto the matrix.
The following examples are intended to illustrate the invention without limiting the same in any manner. These examples report results of the embodiment wherein the test reagent solution is added to the test matrix before the sample.
In all the examples that follow, color intensity is scored as follows:
Negative--no color response
Trace--color response barely visible to naked eye
+1--slight color response
+2--moderate color response
+3--strong color response
+4--very strong color response
EXAMPLE 1
______________________________________Effects of EDTA and Guanidine hydrochloride on vegetable andhemoglobin peroxidase activity on Hemoccult slides. Control Slides: 0.36 mg/ml 0.36 mg/ml no Horseradish Powdered peroxidase Peroxidase Hemoglobin added______________________________________Control I +3 +4 neg.non-treated slidesControl II +3 +3 neg.slides treatedwith H.sub.2 O6M Guanidine +4 +4hydrochloride10mM EDTA +3 +4 neg.10mM EDTA in Trace +4 neg.6M Guanidinehydrochloride100mM EDTA +2 +3 neg.100mM EDTA in Trace +3 neg.6M Guanidinehydrochloride______________________________________
Applications of 25 μl of the treatment solutions were dried on slides, followed by the applications of 25 μl of vegetable peroxidase and hemoglobin (Hb). The slides were developed 17-21 hours after applications.
EXAMPLE 2
______________________________________Effects of EDTA plus Guanidine Hydrochloride on vegetableperoxidases and hemoglobin peroxidase activity onHemoccult slides. 0.36 Turnip Per- 0.36 mg/ml 0.36 oxidase Crude mg/ml Pow- mg/ml Extract Horse- dered Whole (1 mg/ml) radish Hemo- Blood Un- Per- globin Lysate diluted Diluted oxidase______________________________________Control I +4 +4 +4 +3 +3non-treated slidesControl II +3 +4 +4 +3 +3slides treated withH.sub.2 O10mM EDTA in +4 +4 +1 neg. Trace6M Guanidine HCl100mM EDTA in +3 +4 Trace neg. Trace6M Guanidine HCl______________________________________
Applications of EDTA and water treatments (25 μl/slide window) were dried on slides prior to the 25 μl applications of peroxidases and hemoglobin. The slides were developed 17-21 hours after applications.
EXAMPLE 3
______________________________________Whole Blood and Turnip Peroxidase Volume: Volume Mixtures:Effects of EDTA plus Guanidine Hydrochloride.______________________________________Water (Control) Not Treated TreatedWater WaterVolume Turnip Peroxidase Volume Turnip Peroxidaseratio 1 2 3 ratio 1 2 3______________________________________1 +2 +3 +3 1 Neg. Neg. Trace2 +2 2 Neg.3 +1 3 Neg.______________________________________Whole Blood Lysate (Control) Not Treated TreatedWhole Blood Lysate Whole Blood LysateVolume Water Volume Waterratio 1 2 3 ratio 1 2 3______________________________________1 +1 Trace Trace 1 +2 +1 Trace2 +1 2 +23 +1 3 +2______________________________________Whole Blood Lysate With Turnip Peroxidase Not Treated TreatedWhole Blood Lysate Whole Blood LysateVolume Turnip Peroxidase Volume Turnip Peroxidaseratio 1 2 3 ratio 1 2 3______________________________________1 +1 +2 +2 1 +1 +1 Trace2 +2 2 +13 +3 3 +2______________________________________
Undiluted turnip peroxidase extract and 0.06 mg Hb/ml whole blood lysated were combined in the volume: volume ratios indicated of which 25 μl were applied on untreated and treated Hemoccult II slides lot 7087 (10/81). Hemoccult slides were treated with 25 μl 0.01 M EDTA in 6 M Guanidine hydrochloride.
EXAMPLE 4
______________________________________Whole blood and powdered hemoglobin in stool specimens: Timestudy with EDTA plus Guanidine Hydrochloride on Hemoccultslides.Powdered Hemoglobin Whole Blood Lysate0.075 gm Hb/ 0.100 gm Hb/Time 100 gm Specimen 100 gm SpecimenDays Untreated Treated Untreated Treated______________________________________1 +2 +2 +3 +34 +2 +2 +3 +35 +2 +2 +3 +37 +2 +2 +3 +38 +2 +2 +3 +311 +2 +2 +3 +312 +2 +2 +3 +314 +2 +1 +3 +315 +2 +1 +3 +3______________________________________
Stool specimens, negative for occult blood, were "spiked" with powdered hemoglobin and whole blood. Hemoccult slides were treated with 25 μl 0.01 M EDTA in 6 M Guanidine hydrochloride per slide window, dried and spotted with 25 μl hemoglobin and whole blood. The slides were stored in the dark for times indicated.
EXAMPLE 5
__________________________________________________________________________Inhibition of vegetable peroxidases by EDTA plus Guanidine Hydrochlorideon Hemoccult slides. Turnip Turnip Peroxidase Horseradish Peroxidase Diluted Powdered Whole Blood Peroxidase Undiluted 3:1 with Hemoglobin lysate(Hb) 0.36 mg/ml (1 mg/ml) water 0.36 mg/ml 0.36 mg/ml Treated* Untreated Treated* Untreated Treated* Untreated Treated* Untreated Treated* Untreated__________________________________________________________________________Color Trace +4 Trace +3 neg. +2 +3 +3 +3 +3Intensity__________________________________________________________________________ *Treated with 10 mM EDTA in 6M Guanidine hydrochloride.
Hemoccult slides were treated with 10 mM EDTA in 6 M Guanidine hydrochloride, dried and stored in the dark for one month. After one month, 25 μl of hemoglobin and vegetable peroxidase were applied to the slides. The slides were developed 17-21 hours after application of hemoglobin or peroxidase.
EXAMPLE 6
Whole Blood and Turnip Peroxidase Volume: Volume mixtures: Effectiveness of EDTA plus Guanidine hydrochloride with storage time on Hemoccult slides.
FIG. 1. Turnip Peroxidase: Whole Blood=3:1 (vol:vol).
FIG. 2. Turnip Peroxidase: Whole Blood=1:1 (vol:vol).
FIG. 3. Turnip Peroxidase: Whole Blood-1:3 (vol:vol).
Hemoccult slides were treated with 25 μl 10 mM EDTA in 6 M Guanidine hydrochloride per window and dried. Mixtures of 0.06 mg Hb/ml whole blood and undiluted turnip peroxidase extract were prepared volume:volume and 25 μl per window were applied to treated and untreated slides. The slides were stored in the dark at room temperature and developed on days indicated.
EXAMPLE 7
__________________________________________________________________________Hemoglobin and vegetable peroxidases: Effectiveness of EDTA plusGuanidine hydrochloride with storage time on Hemoccult slides. 10 mM EDTA in 6 M Guanidine 1 2 3 4 5 6 7 hydrochloride month months months months months months months__________________________________________________________________________0.36 mg/ml not treated +4 +4 +4 +4 +4 +4 +4HorseradishPeroxidase treated Trace Trace Trace neg. neg. neg. +1Undiluted extract not treated +3 +3 +4 +3 +3 +3 +2TurnipPeroxidase treated Trace neg. Trace Trace Trace Trace TraceDiluted extract not treated +2 +3 +3 -- -- -- --3:1 water:Turnip treated Trace neg. Trace -- -- -- --Peroxidase0.36 mg/ml not treated +3 +3 +3 +3 +3 +3 +3PowderedHemoglobin treated +3 +3 +3 +3 +3 +3 +30.36 mg/ml not treated +3 + 3 +4 +3 +3 +3 +3Whole BloodLysate treated +3 +3 +4 +3 +3 +3 +3__________________________________________________________________________
Hemoccult slides were treated with 25 μl 10 mM EDTA in 6 M Guanidine hydrochloride, dried and stored in the dark at room temperature. At one month intervals, 25 μl hemoglobin or vegetable peroxidase were applied to the slides. The slides were developed at 17-21 hours after application of the hemoglobin or peroxidase.
The following examples illustrate the second preferred embodiment wherein the test reagent solution is added to the test matrix at a time subsequent to the application of the sample. This is presently more preferred because it avoids storage-life problems and permits use of readily commercially available test materials.
Basically, guanidine hydrochloride and EDTA are applied to the fecal occult blood test matrix prior to the normal color development procedure by addition of hydrogen peroxide. This simple modification in technique effectively inhibits peroxidase activity present in the stool specimen and is applicable to any test matrix, regardless of previous chemical impregnation, size or shape of the test matrix.
TEST PROCEDURE
One hundred micro-liters (100 μl) or approximately 2 drops of a solution of guanidine hydrochloride-EDTA (0.01 M EDTA in 3 M guanidine hydrochloride) are applied to the test window of the fecal occult blood test matrix. After approximately 21/2 hours of pretreatment at room temperature, the color developing process is completed by the usual procedure involving the addition of 2 drops of hydrogen peroxide to the slide. A pretreatment period before addition of the peroxide of 2 to 3 hours is required to effectively inhibit peroxidase activity.
The following examples illustrate the effectiveness of peroxidase inhibition by a solution of guanidine hydrochloride (3 M) and EDTA (0.01 M):
EXAMPLE 8
______________________________________Application of Guanidine Hydrochloride-EDTAPrior to Color Development ProcessTime (hours)(pretreatmentprior to addition Horseradish Whole Bloodof peroxide Peroxidase Lysate Powdered Hbreagent) (0.36 mg/ml) (0.36 mgHb/ml) (0.36 mg/ml)______________________________________ 1/2 +4 +4 +411/2 +3 +4 +42 +2 +4 +421/2 +1 +4 +43 Trace +4 +431/2 Trace +4 +44 Neg. +4 +441/2 Neg. +4 +4______________________________________
EXAMPLE 9
______________________________________Effect of Peroxidase Activity on ColorDevelopment Without Prior Treatmentwith Guanidine Hydrochloride and EDTA Horseradish Whole Blood Peroxidase Lysate Powdered HbTime (0.36 mg/ml) (0.36 mg/ml) (0.36 mg/ml)______________________________________ 1/2 +4 +4 +411/2 +4 +4 +42 +4 +4 +421/2 +4 +4 +43 +4 +4 +431/2 +4 +4 +44 +4 +4 +441/2 +4 +4 +4______________________________________
Similar results are obtained using EGTA as a chelating agent and urea or salicylic acid to cleave protein hydrogen bonds.
The above is intended to be illustrative of presently preferred embodiments, and not in any way restrictive on the scope of the invention.
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Diagnostic test device for fecal occult blood utilizing a test matrix such as paper impregnated with guaiac. False-positive results in the presence of peroxidases are prevented by adding to the matrix a compound that cleaves protein hydrogen bonds such as guanidine hydrochloride and a chelating agent that binds calcium and/or magnesium such as EDTA.
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CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 60/515,023 filed Oct. 28, 2003, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a method for bioremediation of a polluting substance, which method utilizes a microorganism, preferably from the domain Archaea. The present invention also provides a product for bioremediation, comprising a microorganism, preferably from the domain Archaea, and a biodegradable carrier.
[0004] 2. Description of Related Art
[0005] Pollution of the earth's environment by harmful and non-decomposable contaminants is a major concern posing a threat to the health and safety of all living creatures. For example, contamination of the world's water resources presents a global environmental hazard. Both commercial and non-commercial shipping vessels generate millions of gallons of hazardous pollutants, including petroleum hydrocarbons. Accidental spills of oil from pipelines, supertankers, land-based tanker trucks, etc. also have resulted in devastation to both marine and terrestrial life.
[0006] There is a well-recognized need for remediation, or the clean up, of pollutants that exist in a variety of settings, including water, soil, and sediment collections.
[0007] Currently, the majority of petroleum wastes are processed via mechanical means, including confinement booms, surface-skimmers, oil-water separators, etc. However, these mechanical methods of petroleum contaminant reduction generally do not sufficiently reduce the levels of petroleum deposits in solution sufficient to protect the environment. For example, a problem known with mechanical confinement technologies is that concentrations of petroleum hydrocarbon contaminants remaining in the water phase often exceed the regulatory-allowed limits for discharge into open waters.
[0008] Since the 1970's, the new technology of bioremediation has evolved wherein naturally occurring microorganisms, such as bacteria, are utilized to actively consume toxic hydrocarbon compounds and transform them into harmless byproducts. Bioremediation takes place when microorganisms are activated and exposed to targeted hydrocarbons or organic compounds and convert them into products such as water-soluble fatty acids, carbon dioxide, water, oxygen, and trace carbon. Bioremediation was successfully utilized during the removal of the Exxon Valdez oil spill.
[0009] Although various mechanical and biochemical means for removal of hydrocarbon pollution are known, few are satisfactory in the perspective of cost, ease of operation, and efficiency. All of the systems have drawbacks and limitations. In some cases, the limitations relate to the degree of removal that can be accomplished with a specific system or piece of equipment. In others, the application of high concentrations of bacteria to a particular polluted area has resulted in secondary pollution due to diffusion of the bacteria to adjacent areas.
[0010] Furthermore, typical products for bioremediation on the market today require extensive packaging and delivery systems that often must be removed from the contaminated site after the bioremediation has taken place. For example, U.S. Pat. No. 6,573,087 B2 (issued Jun. 3, 2003) to Lehr describes timed-released microorganisms packaged in an absorbent matrix for the degradation of hydrocarbons. In the preferred embodiment thereof, a core member, which contains bacteria capable of degrading hydrocarbons, is surrounded by a matrix of a high absorbency cellulose or melt blown polypropylene material which wicks and stores accumulated hydrocarbons for contact with the core member, thereby accomplishing controlled release of the bacteria. Furthermore, the matrix itself is covered with an outer casing preferably of cotton textile material.
[0011] U.S. Pat. No. 5,658, 795 (issued Aug. 19, 1997) to Kato et al. describes a method for biodegradation of a polluting substance wherein a biodegradable carrier is utilized to support an auxotrophic microorganism. The use of a biodegradable material eliminates the problems associated with secondary pollution caused by remaining carrier and damage to the ecosystem caused by the applied microorganism.
[0012] Kato et al. requires the use of auxotrophic bacteria, i.e., bacteria which has lost a metabolic system or biosynthetic system of a certain nutrient and is incapable of producing the nutrient, which requires the supplementation of the nutrient necessary for living and multiplying. Thus, the carrier for the microorganism must also contain the required nutrient, which may be one or more amino acids, nucleic acid bases, vitamins, organic acids, or other growth factors. Without the addition of the nutrient, the bacteria will quickly become extinct without eliminating the hydrocarbon pollutant.
[0013] The present invention provides a method for bioremediation wherein the problems of the prior art are solved. Specifically, the present invention provides a product for bioremediation which is completely biodegradable, thereby solving the problem of secondary pollution. The product of the present invention allows targeted delivery of microbes to contaminated areas to reduce hydrocarbons to environmentally acceptable byproducts, while leaving no resultant waste requiring clean up. The present invention is also extremely simple and cost-effective in its production. The present invention utilizes a microorganism which is not auxotrophic and therefore does not require any additional nutrients in the biodegradable carrier to survive. The lack of necessity of a nutrient in the carrier avoids an extra step in production which is undesirable from a cost and efficiency standpoint. The microorganism is preferably from the domain Archaea, which is more effective than any known bacterium used for bioremediation.
BRIEF SUMMARY OF THE INVENTION
[0014] The present invention provides a product for bioremediation, comprising a biodegradable carrier and a tablet or powder consisting essentially of microorganisms capable of digesting hydrocarbons, an inert material, and optionally trace oil in an amount sufficient to maintain the microorganisms in a dormant state, said microorganisms located entirely within said biodegradable carrier, and wherein the biodegradable carrier is directly in contact with the microorganisms. The microorganisms are preferably from the domain Archaea. The biodegradable carrier is preferably a starch, such as cornstarch, or rice paper, and may contain a hole, slit, opening, pore, etc. The product may also contain a fragrance. The present invention provides a method for bioremediation, comprising the steps of delivering the product described above to a contaminated site, allowing the biodegradable carrier to dissolve, allowing the hydrocarbons to access the microbes, and allowing the microbes to be released into the contaminants to convert the contaminants to natural byproducts. The present invention also provides a method for removing or neutralizing odors in a holding tank, such as a tank in a RV or the bilge area of a ship, comprising the steps of delivering the product described above to a holding tank, allowing the biodegradable carrier to dissolve, allowing the hydrocarbons to access the microbes, and allowing the microbes to be released into the contaminants to remove or neutralize the odors to natural byproducts.
[0015] The present invention also provides a process for producing a product for bioremediation, comprising the steps of: admixing microorganisms capable of digesting hydrocarbons with an inert material and optionally trace oil in an amount sufficient to maintain the microorganisms in a dormant state, to form a mixture; placing the mixture into preformed holes of a tablet-making template, wherein the tablet-making template is a foam; placing the tablet-making template onto a compression press; applying pressure to the tablet-making template to form tablet; extracting the tablet from the tablet-making template; and placing the tablet into a biodegradable carrier wherein the biodegradable carrier surrounds the microorganisms and is in direct contact with the tablet. The microorganisms are preferably from the domain Archaea. The biodegradable carrier is preferably a starch, such as cornstarch, or rice paper. The process described above may also include the steps of inserting a hole, slit, opening, pore, etc. into the biodegradable carrier, or adding a fragrance therein. The present invention also relates to a product for bioremediation produced by the process described above.
[0016] The present invention also provides a method for bioremediation comprising the steps of providing microorganisms capable of degrading hydrocarbons in the form of a tablet or powder, incorporating said microorganisms into a biodegradable carrier, wherein the tablet or powder is in direct contact with the biodegradable carrier, delivering the biodegradable carrier containing the microorganisms to a contaminated site, wherein the biodegradable carrier is dissolved or disintegrated, thereby releasing the microorganisms which bioremediate at the contaminated site. The microorganisms are preferably from the domain Archaea. The biodegradable carrier is preferably a starch, such as cornstarch, or rice paper, and may contain a hole, slit, opening, pore, etc. The product may also contain a fragrance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is an exterior view of the product of the present invention.
[0018] FIG. 2 is a cross-sectional view shown along cut line 2 of FIG. 1 . The interior 1 is made up of microorganisms in an inert material (e.g., clay or bentonite clay) and optionally trace crude oil in an amount sufficient to maintain the microorganisms in a dormant state. The biodegradable carrier 2 is in direct contact with, and completely surrounds, the interior powder or tablet.
[0019] FIGS. 3A and 3B represent cross-dimensional views of a biodegradable cornstarch sheet 3 into which microbes 5 are placed and sealed.
[0020] FIG. 4 is a three-dimensional view of the tablet-making template containing holes 6 .
[0021] FIG. 5 shows microbe-bearing biodegradable carriers 7 , 8 suspended by tethers 9 , 10 .
[0022] FIG. 6 shows microorganisms 11 in a compressed tablet or powder form between dissolvable paper sheets 12 suspended by a tether 13 .
[0023] FIG. 7 is a two-part dissolvable gel-pack capsule containing microbes.
[0024] FIG. 8 is a tablet-wrapping machine showing dispensed tablets being encased in biodegradable cornstarch paper wrapping.
[0025] FIG. 9 is a series of fluted, biodegradable, cornstarch cylinders into which microbes are placed and sealed by biodegradable sheets at the ends of the cylinders.
[0026] FIG. 10 is a packet-making machine showing dispensed packets of microorganisms encased in biodegradable cornstarch paper wrapping.
DETAILED DESCRIPTION OF THE INVENTION
[0027] The present invention relates generally to bioremediation of pollutants on land and in standing or moving water, and specifically to bioremediation of hydrocarbon and organic pollution in fresh and salt water. The invention relates to a biodegradable microorganism-containing product and method of use thereof for removing hydrocarbons from ship vessel bilges, and for cleaning up hydrocarbon spills and deposits on water, for example in catch basins, septic tanks, and grease traps. The present invention also provides a method to eliminate odors such as those that occur in holding tanks, septic systems, grease traps, etc. The microorganism utilized in the present invention is preferably from the domain Archaea. The invention provides a new method and product for bioremediation without introducing into the environment materials which require removal, destruction or cleanup, such as barriers, entrapment, absorbent, or adsorbent devices or materials, and oil-soaked confinement booms or rags. The product of the present invention allows targeted delivery of microbes to contaminated areas to reduce hydrocarbons to environmentally acceptable byproducts, while leaving no resultant waste requiring clean up.
[0028] The present invention also relates to the packaging of microorganisms into a product for release of oil-eating microbes (e.g., millions to trillions) into hydrocarbon contamination or sewage. It combines microbes, either as a tablet or powder directly in contact with a biodegradable carrier to achieve bioremediation without producing unwanted debris. In other words, no matrix (absorbent or otherwise) is necessary to wick hydrocarbons to the oil-eating microbes. Preferably, the invention further does not require the addition of a nutrient for survival of the microorganism, other than an optional trace oil in an amount sufficient to maintain the microorganisms in a dormant state. The lack of necessity of an additional nutrient in the carrier avoids an extra step in production which is undesirable from a cost and efficiency standpoint. The lack of any additional binders, additives, etc. (other than, those in which the microorganisms are commercially packaged) allows for a 100% pure concentration of microorganisms to be exposed to the pollutants. The microbes are preferably from the domain Archaea.
[0029] This invention may be used in the bilge area of both commercial and recreational boats, in military vessels, in marinas, in holding tanks, in cooling tanks, in recreational vehicles (“RVs”), in papermaking plants, in gas production and oil refinery plant sites, in polluted areas restricted by floating booms, in kitchen-waste grease traps, in water run-off catch basins, in waste water, in wetlands, streams, lakes, rivers, underground water, oceans, and any other waters of the world, in polluted soil, waste-treatment sites, farms, i.e., anywhere pollutant hydrocarbons are present and undesired.
The Microorganism
[0030] The present invention may utilize any microorganism known for its ability to remediate, or digest, hydrocarbons. The source of the microorganisms is not limited, so long as the microorganism has the ability to remediate the pollutant to be removed. The microorganism is preferably not auxotrophic.
[0031] The inventor of the present invention recognized the application of microorganisms from the domain Archaea as a preferable element of his invention. It is known in the art that there are three major groups of prokaryotes, i.e., bacteria, Archaea, and Eukarya, which are classified based upon comparative genetic analysis of the nucleotide sequences of their small subunit ribosomal RNA (ssrRNA). In addition to differences in ssrRNA, microorganisms of domain Archaea also possess unifying archaeal features (i.e., no murein in cell wall, ester-linked membrane lipids, etc.) that differentiate them from bacteria. Many of these unique structural and biochemical attributes allow microorganisms of the domain Archaea to live in extreme habitats, including very high temperatures (hyperthermophiles) and very high concentrations of salt (extreme halophiles).
[0032] In a preferred embodiment, MicroSorb® microbial products, sold by Microsorb Environmental Products, Inc. of Norwell, Mass. is the source of hydrocarbon digesting microorganisms used in the present invention. MicroSorb® is designed to optimize the recycling phenomena with the addition of oil-eating microbes. MicroSorb® microbial products contain naturally occurring microbes of the domain Archaea that convert hydrocarbon contaminants into non-toxic components, thereby eliminating the problem of disposal.
[0033] MicroSorb® microbial products are available in three grades: MicroSorb® ER (Emergency Response), MicroSorb® IS (Industrial Strength), and MicroSorb® SC (Super Concentrate). MicroSorb® ER is particularly useful for oil and chemical surface spill treatment, and can be used to attack any petroleum based liquids (i.e., gasoline, fuel oil, and hydrocarbon solvents), virtually any hydrocarbon, and oxygenated hydrocarbon. MicroSorb® ER contains a consortium of over 140 billion hydrocarbon digesting microbes per ounce contained in bentonite clay carrier. MicroSorb® ER is utilized to contain (absorb) and treat sudden surface spills or low level historical releases (weeping) on natural surfaces (i.e., soil), treat oily buildup or sudden spills on concrete or other man-made surfaces to eliminate oil and oil odors, reduce slippery conditions, or for repainting surfaces, treat oily sheens on surface water, and initially treat open contaminated trenches, pits, or excavations for localized and cost-effective bioremediation.
[0034] MicroSorb® IS is particularly useful for bioremediation of organic matter, and can be used to attack any petroleum based liquids (i.e., gasoline, fuel oil, hydrocarbon solvents) and organic wastes), as wells as virtually any hydrocarbon and oxygenated hydrocarbon. MicroSorb® IS contains a consortium of over 560 billion hydrocarbon digesting microbes per ounce contained in bentonite clay carrier. MicroSorb® IS is utilized in the treatment of poultry grow-out houses for reduced odor, reduced wastes, and healthier, quicker grow-out conditions, for a more rapid cleanup of surface releases (versus MicroSorb® ER) when time is of the essence, in the treatment of septic tanks and leaching fields. MicroSorb® IS also works to reduce organic waste buildup in the tank and prevent grease and other fouling agents from entering the leaching field. MicroSorb® IS also treats surface water spills to contain and break down floating hydrocarbons.
[0035] MicroSorb® SC is a super concentrated microbial consortium particularly useful for bioremediation in oxygen-limiting environments, and can be used to attack any petroleum based liquids (i.e., gasoline, fuel oil, hydrocarbon solvents) and organic wastes), as well as virtually any hydrocarbon and oxygenated hydrocarbon. MicroSorb® SC contains a consortium of over 2.5 trillion hydrocarbon digesting microbes per ounce contained in bentonite clay carrier. MicroSorb® SC, because of its high microbe content, has the ability to attack hydrocarbons in oxygen limited environments, such as below grade and in groundwater. MicroSorb® SC is utilized in the treatment of subsurface in situ soil and/or groundwater contamination. MicroSorb® SC is also ideal for treating contamination near building foundations, tanks, or utilities where contamination removal may damage structures, for treating stockpiled (ex situ) contaminated soil, for direct application to septic systems and grease traps to lower solids buildup, reduce odors, and break down fats, oil, and grease. MicroSorb® SC may also be used in sewerage lift stations, piping, and wastewater treatment plants to reduce odors, limit corrosion, and lower solids disposal costs, in manure treatment (chickens, hogs, and cattle) to reduce solids, eliminate odors and ammonia, and improve livestock health and grow-out. MicroSorb® SC is particularly useful for the bioremediation of waste traps in RVs.
[0036] In the present invention, the microorganisms, such as those contained in the MicroSorb® family of products, are preferably contained in an inert preparation of inorganic material (e.g., natural clay). Further, a trace amount of oil (e.g., crude oil or oil on which the microorganisms are weaned) is present in the preparation in order to maintain the microorganisms in a dormant state for storage, transport, etc. However, the present invention does not require the addition of any additional nutrient to the biodegradable carrier, tablet/powder, and/or inert material, such as one or more amino acids, nucleic acid bases, vitamins, organic acids, or other growth factors in order to maintain viability of the microorganisms. Preferably, no enzymes are present in the biodegradable carrier and/or inert preparation. This preparation may be compressed into tablets which absorb water and hydrocarbons
[0037] The tablets dissolve and release the microbes into the contaminant during remediation. The microbes are activated and consume and convert the contaminant into natural byproducts, such as fatty acids, carbon dioxide, water, etc. Once the contaminants have been exhausted, the microbes will either die, return to former natural concentration levels, or be eaten by other organisms.
[0038] As noted above, the present invention may utilize any microorganism known for its ability to remediate, or digest, hydrocarbons. Examples of such microorganisms are bacteria such as Pseudomonas sp., Acinetobacter sp., Metyiosinus sp. and the like which exhibit activities of pollutant-decomposition are suitable for removal of dyes having an aromatic ring or furan structure, pigments, surfactants, surface-coating agents, adhesives, organic solvents, petroleum type pollutants, etc. In addition, oil-eating microbes, such as those commercially available from Oppenheimer Biotechnology Inc. of Austin, Tex., (i.e., the Oppenheimer Formula), which have been collected from natural water and soil sources from around the world, have a particular affinity for consuming hydrocarbon-based products. These microbes may also be used in the method and product of the present invention.
[0039] Several other microorganisms suitable for use in the present invention are described in U.S. Pat. No. 3,843,517, the contents of which are hereby incorporated by reference.
The Product
[0040] The present invention also provides a product for bioremediation, comprising a microorganism, preferably from the domain Archaea, and a biodegradable carrier. The microorganism is preferably contained in an inert material (e.g., clay), which also contains a trace amount of oil (e.g., crude oil) in an amount sufficient to maintain the microorganisms in a dormant state. The product for bioremediation can be prepared as follows.
[0041] The microorganisms are initially housed in an inert material, such as clay or a bentonite clay mixture, which degrades upon contact with water, releasing the microbes. The inert material preferably contains a trace amount of crude oil (e.g., only an amount sufficient to maintain the microorganism in a dormant state). As used herein, “trace amounts” also refers to an insignificant amount, or an amount not visible to the eye or readily measurable, or an amount of oil that is so small that it does not add any significant amount of oil to the hydrocarbon to be remediated. In a preferred embodiment, tablets of the microbes held in this inert material (e.g., clay) are completely enclosed within a biodegradable carrier, which will also suitably degrade when in contact with water.
[0042] The microorganisms may be prepared in tablet form together with an inert carrier by use of a pill-making machine, which preparation is conventional in the art. Preferably, however, the present invention provides a novel, cost-effective, and simple method for preparing the microorganisms in tablet form. Specifically, the present invention utilizes a tablet-making template and a compression press to create the tablets. This unique method for forming tablets does not require the use of any additional binders or additives other than those (e.g., clay and trace amounts of crude oil) in which the microorganisms are commercially packaged, so that the concentration levels of the microorganism are not compromised.
[0043] In a preferred embodiment, the tablet-making template is a piece of foam having the following characteristics: resiliency, flexibility, tear-resistance, and chemical suitability for the microorganism. The tablet-making template is preferably cross-linked polyethylene foam. The tablet-making template can be made of different densities and different foams such as polyethylene, polyurethane, polypropylene, or rubber. Typical examples of such a foam are Volara Type A®, a flexible closed cell irradiation cross-linked polyethylene foam, and Minicel L200® and L300®, closed cell chemically cross-linked polyethylene foams. These products are commercially available from Voltek (Lawrence, Mass.). Suitable cross-linked polyurethane foams are also commercially available from Cellect LLC (St. Johnsville, N.Y.).
[0044] A typical tablet-making template, shown in FIG. 4 , is approximately 10×5.5×⅜″. The template is impregnated with holes 6 approximately ⅝″ wide in which the tablets are to be formed. The skilled artisan would understand that the size and thickness of the template, as well as the depth, diameter, and shape of the holes, may be varied in order to achieve different results. For example, the holes may be varied in order to make different dimensions, sizes, and thickness of the tablets, which in turn affects the properties of the tablets.
[0045] The microorganisms are preferably admixed with an inorganic inert material (e.g., clay) and placed into the holes of the tablet-making template. The template is placed onto a commercial compression press. The type of compression press could be a Hudson or Samco or any other press similar to what the industry knows as a die cutter or a compression machine. Approximately 10-40 tons, and preferably 20-30 tons, of pressure is applied to the tablet-making template of the size 10×5.5×⅜″. The amount of pressure may be increased or decreased depending on the size of the tablet-making template utilized. A mixture of microorganisms in an inert material, preferably with trace amount of crude oil, are spread into the holes of the template and the press is then activated, which compress the foam thereby forming the microorganisms into tablets. The tablets are then extracted from the holes and placed into a biodegradable carrier. When extracted, the tablets may be, in general, slightly larger than the holes of the template due to the flexibility of the foam.
[0046] The method of the present invention provides microorganisms in a tablet form wherein the number of microorganisms living is surprisingly greater than with known tablets. These surprisingly good effects of the inventive method lies in the fact in that the foam of the tablet-making template absorbs the shock and heat of the compression, thereby not killing the microorganisms in the holes. The template is resilient and flexible and spreads the load of the compressor over the full surface of the template, thus putting less pressure on each tablet.
[0047] The invention includes implementing a biodegradable carrier to support the hydrocarbon-digesting microbes. When placed in solution, the carrier will break up, dissolve, and eventually degrade. The microbes will be exposed to, for instance, the hydrocarbons and digest the hydrocarbons and odors.
[0048] The material for the biodegradable carrier includes, for example, cellulose, lignin, starch, agarose, dextran, albumin, chitin, chitosan, filter paper, wood pieces, etc. Typical starches include cornstarch, laundry starch, potato starch, rice starch, and tapioca starch. As defined herein, the biodegradable carrier does not contain wax. A carrier made of such a material is preferred since it encases the microorganism, releases the microorganism relatively readily, is inexpensive, and in some cases, serves as a nutrient for the microorganism itself. A preferred biodegradable carrier is starch, and even more preferably, cornstarch. Another preferred biodegradable carrier is rice paper.
[0049] A preferred biodegradable carrier is Green Cell sheets, which is a starch-based material supplied by KTM Industries, Inc. of Lansing, Mich. That material or similar material has about 90% or greater cornstarch content and about 1-10% of a degradable binder. Methods and materials for manufacturing starch capsules are disclosed in U.S. Pat. No. 6,669,962 to Fanta et al., the contents of which are hereby incorporated by reference.
[0050] Another embodiment has the microbes stored in a gel-pack container, made from an environmentally friendly gelatin or cellulose derivative. These dissolvable containers can be used for targeted microbe delivery.
[0051] Another embodiment has the microbes stored in other biodegradable carriers, such as tallow, fish entrails, algae, seaweed and seaweed extracts, such as alginates and carageenans, polysaccharides, water-soluble polymers, and plant extracts (e.g., vegetable matter), such as konjac, petin, arabinoglactan, etc.
[0052] Examples of water-soluble polymers are pullulan, hydroxypropylmethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, polyvinyl pyrrolidone, carboxymethyl cellulose, polyvinyl alcohol, sodium alginate, polyethylene glycol, xanthan gum, tragacanth gum, guar gum, acacia gum, arabic gum, polyacrylic acid, methylmethacrylate copolymer, carboxyvinyl polymer, amylose, high amylose starch, hydroxypropylated high amylose starch, hydroxypropylated high amylose starch, dextrin, pectin, chitin, chitosan, levan, elsinan, collagen, gelatin, zein, gluten, soy protein isolate, whey protein isolate, casein, polysaccharides, natural gums, polyacrylates, starch, karaya gum, gelatin, and mixtures thereof.
[0053] The biodegradable carrier may preferentially be composed of pullulan. Pullulan content products in the form of fast-dissolving films are described in U.S. Pat. Nos. 5,518,902 and 5,411,945 to Ozaki et al., U.S. Pat. No. 4,851,394 to Kubodera, U.S. Pat. Nos. 3,784,390 and 4,562,394 to Hijiya et al., U.S. Pat. No. 4,623,394 to Nakamura et al., JP Patent Document JP5-1198, WO 99/17753, WO 98/26780, WO 98/20862, and WO 98/26763. The contents of all of these documents are incorporated herein by reference. Formation of film is described, for example, U.S. Patent Application 2003-30224090 to Pearce et al., the contents of which are incorporated herein by reference.
[0054] The biodegradable carrier may preferentially be composed of polyvinyl alcohol, and preferentially a polyvinyl alcohol in the form of a film. Polyvinyl alcohol films are commercially available from MonoSol (Portage, Ind.). Examples thereof are MonoSol® films E-6030, M-7031, M-7061, M-8534, M-8630, and M-9500. Monosol® films are environmentally acceptable, non-toxic, fully biodegradable, and can be sealed by heat. They are dissolvable in hot and/or cold water. These biodegradable carriers are described in U.S. Pat. No. 6,787,512 to Verrall et al., and U.S. Pat. No. 6,484,879 to Desmarais et al. The contents of these patents are hereby incorporated by reference.
[0055] The biodegradable carrier may be in any shape, and may have a slit or slits, a hole or holes, a pore or pores, or any other type of suitable opening to enhance biodegradation. The skilled artisan would understand that the rate of degradation of the biodegradable carrier may be controlled by selecting the kind and properties of the material thereof. For example, the diameter and shape of the pores, the size and shape of the carrier, etc. are suitably selected in consideration of the material. In selecting the above requirements, the factors to be considered in connection with the degradation rate include the kind, amount, and carrier-degradation activity of the microorganism, and the volume of the pollutant to be remediated.
[0056] Any and all of the biodegradable carriers mentioned herein can be coated with a slow-dissolving time-release agent, allowing longer release time and a more equalized disbursement of the microbes.
[0057] The microorganisms, in the form of a powder as commercially available, or in the form of a compressed tablet, or a powder made from the tablet, are packaged directly in contact with a biodegradable carrier to achieve bioremediation without producing unwanted debris. The biodegradable carrier housing the microbes serves two purposes.
[0058] First, the biodegradable carrier serves as a jacket, protecting the tablets or powder, etc. from excess moisture or crushing, and preventing premature disintegration and release of microbes. Within the flexible jacket, the substance of the tablets or powder, etc. is not lost, even if crushed.
[0059] Additionally, the biodegradable carrier may be selected based on its degradation rate in water, thereby allowing for a release of the microbes over time. The biodegradable carriers can be trolled through water spills and cover a much larger area with microbes than if the microbes were merely dropped directly into the water.
[0060] The invention provides microbe-bearing tablets sealed within two or more sheets of a biodegradable carrier, as shown in FIG. 1 . In one embodiment the biodegradable carrier is comprised of two sheets of wrapping paper having a content of cornstarch or other suitable biodegradable material. In one form, as shown in FIG. 2 , the mixture of microbes, inert material, and trace crude oil 1 are encased between layers of cornstarch paper or rice paper 2 , and moisture or adhesive holds the carrier layers closed.
[0061] FIG. 3A shows a block of biodegradable cornstarch 3 sliced open and containing a hollow cavity 4 . Microbes 5 are inserted into the hollow cavity, and then the cut is sealed with moisture or glue to reform the whole block, as shown in FIG. 3B . FIG. 5 shows microbe-bearing biodegradable carriers 7 , 8 suspended by tethers 9 , 10 . FIG. 6 shows microorganisms 11 in a compressed tablet or powder form between dissolvable paper sheets 12 suspended by a tether 13 . The microbes are encased by the biodegradable carrier, which is folded along a center-line 14 and secured with moisture or glue along the edges 15 . The apparatus shown in FIG. 6 may or may not have a tether.
[0062] FIG. 7 shows a 2-piece cellulose gel-pack 16 which contains microbes, preferably admixed with clay and a trace amount of crude oil, in tablet form 17 .
[0063] The product of the present invention may be produced as follows.
[0064] In one embodiment, to encase the microbe-containing tablets in the biodegradable carrier, the tablets are placed in a hopper and fed through a die molder and cutter. The biodegradable carrier is in the form of cornstarch wrapping paper or rice paper. The paper is drawn and then spooled from two supply rolls, one on either side of a tablet dispenser. The tablets are then pressed between two wrapper sheets by the die molding. The wrapper sheets are sealed via a solvent-based joint or seal, which joint or seal is 100% natural and biodegradable, such as water, epoxy, starch- or sugar-based glue. Cutters trim, cut and remove the excess paper wrapper, and the wrapped tablet is expelled with perforations for ease of dispensing. The excess paper wrappers with the punched out holes are spooled and bundled onto a scrap roller for recycling.
[0065] This embodiment is specifically shown in FIG. 8 . FIG. 8 shows a tablet hopper 18 feeding microbe-containing tablets 19 into a die molder 20 , 21 and cutter 22 , 23 . Sheets of biodegradable carrier in the form of wrapping sheets 24 , 25 are spooled from two supply rolls 26 , 27 , one on either side of the tablet 19 , via spooling rollers 32 , 33 . Solvent 31 is applied to the biodegradable carrier. The tablet 19 is then pressed between the two sheets 24 , 25 by the die molding 20 , 21 and sealed with moisture 31 . A cutter 22 , 23 slices away the excess wrapper 29 and the jacketed tablet is expelled. A stripping wheel 28 , strips excess wrapper 29 and bundles it onto a scrap roller 30 . Preferably, a drying conveyor 51 carries away the finished product 52 . The apparatus may also utilize a tablet inserter assist 53 .
[0066] The wrapper paper may also be preformed into casings for microbe tablet reception. One form is small connected and aligned cylinders with central voids for receiving the tablets, and first and second thin layers for closing the ends of the central voids. The microbe tablets are inserted into fluted openings in the shell, and then a layer of wrapper paper is secured across the top and bottom of the fluting, sealing the microbe-bearing tablets within the shell. The resulting soluble shell is both more buoyant and impact resistant than the paper wrapping and degrades over a longer period of time, due to its increased mass.
[0067] This embodiment of the present invention is shown in FIG. 9 . FIG. 9 shows a series 34 of cylindrical, biodegradable tubular casings 35 with hollow tubular openings 36 and with connecting web 37 . A bottom layer of biodegradable sheet strip 38 is secured across the bottom 39 of the cylinders 35 with an adhesive, e.g., water or glue. Microbes in powder or tablets 40 are inserted into the openings 36 . A layer of biodegradable carrier 41 is secured across the top 42 of the cylinders 35 , sealing the openings 36 . The web may be separated such as by tearing web 37 and strips 38 , 41 to produce individual closed tubes for distribution over a spill.
[0068] Another form of casing is a single strip of cornstarch. The strip is sliced open longitudinally and the microbe tablets are inserted into a hollow between the layers and in openings. The layers of the strip are then rejoined and sealed with moisture or adhesive, encasing the microbe-bearing tablets within the strips. The strips may be cut into blocks or may be partially separated into tearable blocks for scattering over a spill on land and/or water. Greater buoyancy and impact resistance are achieved with these strips and blocks casing, as well as a slow rate of degradation, if desired.
[0069] In a similar procedure, a sheet of biodegradable cornstarch is divided into strips and is slit longitudinally into layers. The layers are joined together in alternating joints similar to web 37 , leaving openings similar to openings 36 in tubular casings 35 . Microbe-containing tablets or powder 40 are added to the openings, which are closed by sealing tops and bottoms or by pressing the layers together between the joints to entrap the microbe tablets or powder. Alternatively, the strips are split longitudinally and the microbe tablets or powder are inserted between the strips before dampening the strips and pressing them back together. In the latter cases the strips may be partially cut transversely into separable blocks. Alternatively, the tubular casings may be arranged as a floating barrier allowing water and hydrocarbon penetration to dissolve the biodegradable carrier while the microbes are released to do their work.
[0070] FIG. 10 shows an apparatus for making packets containing the microorganisms in powder form. A flat roll stock 43 of biodegradable carrier is fed into the machine and folded by a plow fold 44 . Solvent 45 is applied to the biodegradable carrier. The plow is opened at the traveling/opening plow 46 and sealed at the sealer 50 . An auger filler 47 inserts the microorganisms in powder form into the biodegradable carrier. The top is sealed 48 and cut by a cutter 49 . Preferably, a drying conveyor 51 carries away the finished product.
[0071] It will be understood by those of ordinary skill in the art that other materials/fillers may be added to the product as desired to improve odor, etc. For example, the addition of fragrance or flavoring aromatic on the exterior of the cornstarch is useful for improving the odor of a holding tank. Preferably, however, the tablet or powder etc. contains only microorganisms together with an inert carrier (e.g., clay) when necessary without any other additive or component introduced therein. The tablet or power is then placed in direct contact with a biodegradable carrier preferably without any other intervening material between the tablet/powder etc. and biodegradable carrier. That is, the tablet or power is preferably in direct contact with the biodegradable carrier.
[0072] The invention provides a method of reducing or eliminating pollutants through bioremediation comprising providing microorganisms in the form of tablets or powder, incorporating the microorganisms into a biodegradable carrier, delivering the carrier with the microbes to a contaminated site, dissolving or disintegrating the soluble carrier, releasing the microbes from the carrier, and digesting hydrocarbons and organic pollutants at the contaminated site with the microbes.
[0073] The product of the present invention can be used effectively on any of the following materials: acenapthene, alkylamine oxides, benzene, chlorinated phenols, chloro naphthalene, cyanide, diethleneglycol, fuel oils #1-6, heptane, isoprene, long chain alkenes, mercaptan, motor oils (not synthetic), nitrated phenols, oil based paints, pentane, phthalate esters, secondary alkylbenzene, trichloroethylene, xylene, acrolein, animal (including human) wastes, biphenyl, chlorobenzene, crude oil, dichlorobenzene, ethylbenzene, gasoline, hexane, hexane, jet fuels, lubricating oils, methylene chloride, MTBE, oil based fluids, organic herbicides, phenoxyacetates, polycyclic aromatics, sewage, vegetable oils, acrylonitrile, aromatics, brake fluids, chloroform, cutting oils, diesel fuels, fluoranthene, grease, hydraulic oils, kerosene, marine fuels, monoalkylbenzenes, naphthalenes, oil based inks, organic pesticides, phenylureas, pulp by-products, toluene, and volatile organic compounds (VOCs).
[0074] Upon delivery to the contaminated site, the biodegradable carrier begins to dissolve, allowing the water and hydrocarbons to access the microbes. As the clay disintegrates, the microbes are released into the contaminants and begin converting the hydrocarbons to natural byproducts. As the microbes feed on the hydrocarbons, the population of microbes increases, allowing faster and more effective contaminant reduction.
[0075] This increased population of microbes is sustainable only as long as sufficient hydrocarbons remain. Once the hydrocarbons have been remediated, the microbes die, return to initial levels, or are consumed by other organisms in the environment.
[0076] The product of the present invention may be distributed over oil spills from airplanes or helicopters or high-speed boats or from a ship from which the spill originated. The product may also be deployed in storm water catch basins or grease traps. The product may be suspended from tethers into contaminated areas. As biodegradable carrier dissolves, the tablets disintegrate and the contaminants are exposed to the microbes within the carrier.
[0077] A preferred method for destroying contaminant hydrocarbons places tableted (e.g., with clay) microbes or powder into dissolvable, degradable or disintegratable floaters (e.g., comprising about 50-99% by weight cornstarch and about 50-1% by weight binder), formed as a paper or cellular carrier adapted to float in or on the surface of the body of water. The floaters containing the microbes are placed on pollution in a body of water. The floaters become wet and dissolve, degrade or disintegrate, and the contaminant hydrocarbons come into contact with the microbes from the floaters. The microbes then digest the contaminant hydrocarbons. Preferable carriers or floaters contain 90% or more cornstarch or other suitably biodegradable material.
[0078] While the invention has been described with reference to specific embodiments, modifications and variations of the invention may be constructed without departing from the scope of the invention, which is defined in the following claims.
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A product for bioremediation, comprising a biodegradable carrier and a tablet or powder consisting essentially of microorganisms capable of digesting hydrocarbons, an inert material, and optionally trace oil in an amount sufficient to maintain the microorganisms in a dormant state, said microorganisms located entirely within said biodegradable carrier, and wherein the biodegradable carrier is directly in contact with the microorganisms.
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This application is a division of application Ser. No. 08/134,968 filed Oct. 13, 1993 and now abandoned, said Ser. No. 08/134,968 being a Continuation-In-Part of application Ser. No. 07/807,041 filed Dec. 11, 1991 and issued on Nov. 16, 1993 as U.S. Pat. No. 5,262,732.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an apparatus for detecting the degree of deterioration of lubricating oil and, more particularly, to such an apparatus detecting deterioration due to the following: corrosive products caused by such conditions as oxidation, nitration, and the formation of acids; oil insoluble contaminants such as water and glycol coolants; and ferromagnetic particles caused by system wear.
2. Description of the Prior Art
The presence of corrosive products, oil insoluble contaminants or ferromagnetic particles in a lubricating oil can create a threat to the system in which the oil is used because of the unnecessary wear and damage that can occur to the system if the oil is not promptly changed.
Many methods and devices have been developed to detect the contamination or breakdown of oil. One such device, shown in U.S. Pat. No. 4,646,070 issued to Yasubara, discloses a device for detecting deterioration in lubricating oil which comprises a pair of capacitor electrodes positioned in the lubricating oil. The device uses the oil as a dielectric between the sensors to develop a frequency voltage signal across the sensor capacitor, thus determining the dielectric and deterioration of the oil. A major drawback of this device and others is that they do not inform the tester of the specific type or magnitude of deterioration in the system.
The preferred embodiment of the present invention allows simultaneous testing and identification of corrosive products, contamination, and ferromagnetic wear particles. Thus, since the apparatus detects the type of products present in the oil, a user is able to make a more knowledgeable determination of the conditions causing the deterioration of the oil. Furthermore, the device provides this determination much more economically than laboratory testing. The device also allows multiple tests of the same oil sample because it does not consume the sample during the testing process. Preferably, the device allows testing of the oil outside the system in which the oil is used, thereby allowing the oils of many different systems to be tested by the same device.
SUMMARY OF THE INVENTION
The present invention provides an apparatus for monitoring the condition of lubricating oil preferably for the possible presence of corrosive products, contamination such as water, and ferromagnetic metals in the oil. The apparatus includes containing means for holding the lubricating oil, magnet means for inducing a magnetic field upon the lubricating oil, sensor means for determining a physical property of the oil in the presence of a magnetic field and optical magnifying means to assist visual analysis of debris separated from the oil.
Preferably, the magnet means includes a permanent magnet, an electromagnet and a switching means for changing the polarity of the electromagnet. Thus, both the permanent magnet and the electromagnet simultaneously impose their magnetic fields upon the lubricating oil attracting any ferromagnetic particles in the oil. Furthermore, in the preferred embodiment, the magnetic field of the electromagnet changes polarity over time, alternately reinforcing and canceling the permanent magnetic field, thereby vibrating and reorienting the ferromagnetic particles with the change in the electromagnet's flux orientation without repulsing the particles away from the sensor.
The sensor means preferably includes a sensor, a means for monitoring the output of the sensor, and a means for processing the sensor's output. The apparatus is assembled in a manner allowing the contained oil to be exposed to the sensor, and the sensor has at least two conductors for which the oil provides an insulating dielectric medium. Thus, the sensor acts as a capacitor and its capacitance varies in relation to at least the area of the conductors, the distance between the conductors, and the dielectric constant and other properties of the oil. This relationship between the sensor and the lubricating oil allows the determination of the properties of the oil as it is influenced by the magnetic field.
In the preferred embodiment, the processing means of the invention determines the amount and type of deterioration in the oil by comparing the capacitance of the sensor when exposed to a test oil sample to the capacitance of the sensor when exposed to a pure calibration sample of the type of oil tested. A higher capacitance in the test oil (relative to the calibration oil) that remains relatively constant over time indicates the presence of corrosive products. A steady increase of the sensor's capacitance while exposed to the test oil indicates the presence of contamination in the oil. A fluctuating increase of the sensor's capacitance while exposed to the test oil indicates the presence of ferromagnetic particles in the oil. The changing polarity of the electromagnet causes the ferromagnetic particles to reorient thereby fluctuating the increase of the sensor's capacitance.
The invention takes advantage of the characteristic differences between oil and its contaminants. Oil, for example, has a lower density than most contaminants, including water. As a result, gravity is likely to draw the contaminants to the sensor. Also, most contaminants possess electrical characteristics that differ widely from those of oil. Lastly, many contaminants have a magnetic response. Oils normally do not have a magnetic response. Such differences make it possible for the invention to discriminate between oil and virtually every likely contaminant.
Further details and advantages of this apparatus will become more apparent in the following description and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention may best be understood by reference to the Detailed Description of a preferred embodiment when considered in conjunction with the Drawings in which:
FIG. 1 is a diagrammatical block diagram of a preferred embodiment of the Oil Monitor;
FIG. 2 is a plan view of the Oil Monitor showing the sensor;
FIG. 3 is a somewhat diagrammatic perspective view of the Oil Monitor.
FIG. 4 is a circuit diagram of the sensor and associated analog circuit; and
FIG. 5 is a circuit diagram of the microprocessor and associated circuitry that monitors the sensor and produces an output.
FIG. 6 is a graph of frequency vs time data taken by the invention from uncontaminated lubricating oil.
FIG. 7 is a graph of frequency vs time data taken by the invention from lubricating oil used in a pump having significant use and wear.
FIG. 8 is a graph of frequency vs time data taken by the invention from lubricating oil used in a turbine having approximately 0.13% water entrained thereon.
FIG. 9 is a representative graph of the invention Contamination Index vs Water Content.
FIG. 10 is a graph of the invention Ferromagnetic Index vs Iron Content.
FIG. 11 is a graph of the invention OilLife Index™ vs. percentage of water entrained in lubrication oil.
FIG. 12 illustrates an expanded use embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings wherein the representations depict the preferred embodiment, there is shown in FIG. 1 a container 10 for holding the sample of lubricating oil that is to be tested. The container has an open mouth 12 and a removable and resealable lid 14 for sealably attaching over the mouth 12. For testing the oil, the container 10 is placed in a measurement position which preferably entails orienting the container 10 vertically with the mouth 12 situated downward so that the mouth 12 covers a horizontally placed sensor 16 thereby allowing the oil to flow down into welled contact with the sensor 16. The measurement position further allows gravity to influence the oil held in the container 10 thereby causing any contaminants in the oil to migrate toward the sensor 16.
In FIG. 1, the sensor 16 is symbolically represented and is shown removed from the mouth 12 for clarity of illustration. It will be understood that the sensor 16 seals against the mouth 12 to close the container 10 and contain the oil.
A permanent magnet 18 is placed vertically beneath the sensor 16 to allow the magnetic field produced by the permanent magnet 18 to attract any ferromagnetic particles in the oil toward the sensor 16. An electromagnet 20 is located vertically beneath the permanent magnet 18 to allow the magnetic field produced by the electromagnet 20 to act in conjunction or opposition to the permanent magnet 18 depending on the polarity of the electromagnet 20. The electromagnet 20 is electrically connected to switch 22 which is in turn electrically connected to an electromagnet voltage supply 23. The switch 22 and the electromagnet voltage supply 23 allow the electromagnet to be turned on in a north-south orientation, turned on in a south-north orientation, or turned off. The switch 22 in the preferred embodiment is electrically connected to a microprocessor circuit 24 which controls the change in the polarity of the electromagnet 20 as well as the rate at which the electromagnet 20 is turned on and off, which is preferably about one (1) cycle per second. In this embodiment, the electromagnet 20 is a model EMR75 manufactured by Miami Magnet Company operating at 12 volts and about 750 milliamps. The permanent magnet 18 has a diameter of one inch, a thickness of one quarter (1/4) inch and a strength that about matches electromagnet 20.
The sensor 16 is electrically connected to an oscillator circuit 26 which uses the sensor 16 as a capacitor to generate an output signal at a frequency corresponding to the capacitance. The oscillator circuit 26 is electrically connected to the microprocessor circuit 24 which uses the generated signal frequency to determine the presence and magnitude of corrosive products, contamination, and ferromagnetic particles in the oil. The microprocessor 24 is electrically connected to the display 28 which outputs the results of the microprocessor's determinations.
FIG. 2 depicts an enlarged, somewhat diagrammatic, top view of the preferred embodiment of the sensor 16 as mounted to the test box 30 which also contains the permanent magnet 18, the electromagnet 20, the switch 22, the electromagnet voltage supply 23, and the oscillator circuit 26 of FIG. 1. The preferred sensor 16 is constructed in a open grid-like formation and is formed from two conductors 32a and 32b having extensions forming concentric half circles. The oil which flows into and adjacent to the sensor acts as the insulating dielectric medium between the conductors 32a and 32b. Thus, the conductors 32a and 32b act as capacitor plates with the capacitance varying with, at least, the area of the conductors 32a and 32b, the distance between the conductors 32a and 32b, and the dielectric constant of the oil. Numerous capacitance type sensors could be used, but in this embodiment, the sensor has a diameter of about one inch; the conductors 32a and 32b have a diameter of about 250 microns and are spaced apart a distance of about 250 microns; and the sensor 16 has a capacitance in air of about 30 picofarads.
FIG. 3 depicts an external, somewhat diagrammatic, view of the preferred embodiment of the apparatus. The container 10 is shown in the measurement position on the test box 30. A shielded serial cable 34 electrically connects the components in the test box 30 at connector port 74a to those components in the display box 36 by means of connector port 74b. The display box 36 encloses the microprocessor 24 of FIG. 1. The display 28 is preferably an LCD for displaying the value of contamination, corrosion and ferromagnetic particle levels. The display 28 is mounted on the display box 36 and is electrically connected to the microprocessor 24 within the box. Further depicted are three LEDs, 38a, 38b and 38c, that are electrically connected to the microprocessor 24 within the display box 36 and energized corresponding to the changing levels of corrosion, contamination or ferromagnetic particles.
FIG. 4 depicts the preferred embodiment of the internal circuitry of the test box 30 shown in FIG. 3. The oscillator circuit 26 performs the function of generating a frequency pulse based upon the capacitance of the sensor 16. The oil in the sensor 16 acts as the dielectric medium, thereby altering the capacitance of the sensor. The capacitance increases as the dielectric increases (see Formula 1) causing an overall decrease in the frequency produced by the oscillator circuit 26. The presence of polar oxides in the oil causes an increase in the dielectric constant. Additionally, since water has a higher dielectric content than oil, its presence in the oil will cause an increase in the dielectric constant of the oil as the water settles into the vicinity of the sensor 16. If a substantial quantity of water accumulates on the sensor 16, it can cause the sensor 16 to be shorted. The presence of ferromagnetic particles in the oil also causes an increase in the capacitance of the sensor 16 because the accumulation in particles on the sensor increases the sensor's surface area and capacitance in accordance with Formula 1.
C=k*E*(A/d) Formula 1:
where: C=the capacitance of the sensor 16; k=the dielectric constant of the oil in the sensor 16; A=the surface area of the sensor 16; and, d=the distance between the sections of the sensor.
The sensor 16 is connected to a pin 42 of a monostable multivibrator 40 and is connected in parallel with the resistor 44 to pin 46 and pin 48 of the monostable multivibrator 40. A constant voltage source 50 is connected to pins 52, 54 and 56 of the monostable multivibrator 40 while pins 58,60 and 62 are grounded. Pins 52, 54 and 56 are also connected to ground through a, preferably, 0.1 microfarad capacitor 57. Thus, sensor 16 is connected in an R-C circuit to determine the frequency of the signal (pulses) from pin 64. The preferred monostable multivibrator is a general CMOS logic chip Model 4047.
The pin 64 which carries the oscillator signal pulses is connected to a pin 68 of a non-inverting buffer chip 66 which isolates the signal and outputs it from pin 70. The pin 70 is connected to a pin 72a of a connector port 74a. A signal is thereby sent through the connector port 74a along the serial cable 34 of FIG. 3 to an identical connector port 74b of the display box 36 of FIG. 3.
The connector port 74a also receives signals from the microprocessor 24 from pins 76a and 78a of the connector port 74a. These signals control the switch 22 for changing the polarity of the electromagnet 20 and for turning the electromagnet 20 on or off. As the permanent magnet 18 continuously attracts ferromagnetic particles onto the surface of the sensor 16, the electromagnet, when turned on in opposition to the permanent magnet 18, will cause the particles on the sensor to shift thereby changing the surface area of the sensor which results in an altered frequency output from the monostable multivibrator 40. Thus, the electromagnet will cause a fluctuation in output pulses as its polarity is changed if ferromagnetic particles are present in the oil. In the preferred embodiment, an electromagnet is employed for shifting the ferromagnetic particles in the vicinity of the sensor, but it will be understood by those of ordinary skill in the art that a similar effect could be produced by a movable permanent magnet that could be shifted or rotated to change the magnetic field. Furthermore, in the preferred embodiment, the electromagnet's polarity is reversed to produce the maximum fluctuation while continuously attracting particles with the permanent magnet 18. Persons knowledgeable in the art will further understand that total reversal of the polarity of the electromagnet is not required.
The pin 76a of connector port 74a is connected to a pin 80 of the buffer chip 66 which isolates the switching signal and outputs it from pin 82. The pin 82 is connected in series with a resistor 84 to the base of an NPN transistor 86. The pin 78a of connector port 74a is connected to pin 88 of the buffer chip 66 which isolates the signal and outputs it from the pin 90. The pin 90 is connected in series with a resistor 92 to the base of an NPN transistor 94. The emitters of the transistors 86 and 94 are tied together and attached to a signal ground wire 95 which acts to reduce noise in the system. The collector of transistor 86 is connected in series through resistors 96 and 98 to the electromagnet power supply 23, which provides V mag , and further connected through resistor 98 to the base of a PNP transistor 100. A diode 102 is coupled across the emitter and collector of transistor 100 thus acting as a protection device for transient relief. The emitter of transistor 100 is further connected to the electromagnet voltage supply 23, and the collector of transistor 106 is further coupled to the electromagnet 20. The collector of transistor 94 is connected in series to the electromagnet power supply 23 through resistors 104 and 107 and is further connected to the base of a PNP transistor 106 through resistor 107. A diode 108 is coupled across the emitter and collector of transistor 106 thus acting as a protection device for transient relief. The emitter of transistor 106 is further connected to the electromagnet voltage supply 23 (preferably a battery), and the collector of transistor 106 is further connected to the electromagnet 20.
The pin 82 of the buffer chip 66 is also coupled with a pin 112 of a Darlington driver chip 110 which operates as a current sink, dependent upon the logic level, and is connected from pin 114 to the electromagnet 20 in conjunction with the collector of transistor 106. The pin 90 of buffer chip 66 is connected to a pin 116 of the driver chip 110 which is in turn coupled from pin 118 to the electromagnet 20 in conjunction with the collector of the transistor 100. This configuration allows the current flow to the electromagnet 20 to be alternated or shut off completely by the microprocessor 24 thus providing the switch 22.
The driver chip 110 is connected to the signal ground wire 95 through a pin 118 and is connected to the electromagnet voltage supply 23 through a pin 120 which is further coupled through a series capacitor 122 to the signal ground wire. The signal ground wire 95 is connected to pin 124a of the connector port 74a.
The connector port 74a has pins 126a,128a, and 130a connected to ground and has pin 132a connected through a diode 134 to the electromagnet power supply 23.
The buffer chip 66 has pin 136 connected to the constant voltage source 50 which is in turn coupled to ground through capacitor 138. The buffer chip also has pins 140, 142 and 144 coupled to ground.
FIG. 5 depicts the internal circuitry of the display box 36 of FIG. 3. The connector port 74b connects the test box 30 to the shielded serial cable 34. The pin 72b carries the oscillator pulse and is connected to the microprocessor 24 at pin 146. The preferred microprocessor is an HCMoss microcontroller unit model MC68HC705C8 with erasable programmable read only memory. The microprocessor 24 counts the frequency pulses produced by the multivibrator 40 to determine the amount of contamination, corrosive products and ferromagnetic particles in the test oil.
A fresh, petroleum-based lubricating oil is primarily composed of hydrocarbon molecules with no net electrical charge and which are weakly polar or have a non-polar charge distribution. Fresh mineral oils can be characterized as having a very high electrical resistance and a relatively low dielectric constant (permittivity). These electrical properties change as the oil degrades and becomes contaminated. Specifically, increases in insoluble content, the presence of moisture and acids, or the presence of conductive metallic debris will increase the dielectric constant of an oil, or reduce its resistance, or both.
A combined measure of permittivity and resistivity can be made by measuring the AC impedance or effective capacitance (rate of charge over applied potential) across two plates separated by a quantity of oil. An approximate model for the system is an ideal capacitor influenced primarily by permittivity and a parallel resistance primarily influenced by ionic conduction. Charge mobility not involving conductive particles in a dielectric fluid involves mechanical motion of charged or dipole particles in the fluid. Therefore, system impedance is tied to the parameters which describe the hydrodynamics of particles moving in a fluid. These parameters include the temperature-dependent oil viscosity, the applied (electrical) forces, particle size, and particle shape. As might be expected, increasing molecular size and/or increasing viscosity damps particle response to electrical force, resulting in a decrease in the frequency at which the maximum effective capacitance is achieved. Consequently, sample readings of absolute instantaneous permittivity and loss performed with a conventional dielectrictrometer will provide a limited amount of information about the bulk oil chemistry.
The strength of the present invention is based on measuring the time-rate-of-change of effective capacitance in the presence of time-varying magnetic and electric fields over a standard test period, 500 seconds, for example. These applied fields act along with gravity to draw ferromagnetic particles, polar insolubles, and conductive metal particles down onto the sensor 16. Consequently, the time-rate-of-change values are specifically related to the amount and species of contaminates which are extracted from the oil rather than to the general, bulk oil properties.
The invention uniquely identifies ferromagnetic debris by comparing the time-rate-of-change in a magnet off state to the time-rate-of-change in the magnet states. In addition, the instrument also reads the absolute effective capacitance at the beginning of the test. This value can be used to compare the test oil to a sample of the fresh bulk oil when the results of the fresh oil calibration test have been stored. The comparison provides a non-specific indication of changes in the bulk oil chemistry. In the absence of a calibration sample, this value should still be tended over time to detect sudden changes in bulk oil chemistry which typically accompany additive depletion or gross contamination.
FIG. 6 illustrates how the invention "sees" a fresh oil. The broad curve across the top of the plot represents sequential frequency readings of an oscillating circuit which decreases with the increases in effective system capacitance. The plot is smooth with very little downward slope indicating that there was little change in the effective capacitance during the test. We know, therefore, that the contaminant population is small and benign. There are no diverging curves for the magnet on states.
FIG. 7 illustrates how the instrument "sees" the same pump oil after it has been in service in a pump experiencing significant wear. Note the much steeper downward slope and the increasing separation of the magnet on states (two lower curves) from the upper magnet off state curve. This separation is the indication of ferrous debris. Also note that in this case the magnet on curves have a jagged and spiked profile at about 120 seconds into the test when relatively large magnetic particle(s) were forced onto the sensor, while the magnet off curve is relatively smooth.
FIG. 8 illustrates how a turbine oil with roughly 1300 ppm (0.13%) water appears to the instrument. There is a steep and nearly linear downward slope indicating that the contaminate is being primarily drawn onto the grid by gravity rather than by the magnetic fields with their spatial gradient. This is confirmed by the fact that there is also no divergence of the magnet on curves from the magnet off curves. Also note the perturbation in the curve at about 260 seconds caused by a droplet of "free" water contacting the grid as opposed to finely dispersed moisture.
Upon initial application of power to the microprocessor 24, the microprocessor 24 is set in calibration mode whereby it stores certain calibration counts for use in the test mode. The calibration mode stores certain values which will be used as the "normal" values for the oil to be tested. These values are obtained from running the calibration sequence upon an unused sample of the oil. The calibration sequence is similar to the test sequence. To perform the calibration sequence, the calibration oil is put into the container 10, and the container is placed in measurement position.
The microprocessor then begins receiving and counting the pulses output from the monostable multivibrator 40. Pulse counts are made when the electromagnet is turned on in north-south polarity, turned on in south-north polarity, and turned off. In the preferred embodiment, these three count readings constitute one cycle.
The mean calibration value, M c , is determined over a number of cycles, preferably, twenty cycles, and, preferably, the first ten of which are counted and ignored. During each cycle between ten and twenty cycles, the pulse count is stored while the electromagnet is off, and the mean value of the stored pulse counts is stored as M c . The number of cycles used to determine M c is a matter of design choice, but it is preferred to ignore the first few cycles and then determine an average based on a number measurements taken over a number of cycles.
After the twenty-first cycle, the pulse count when the electromagnet is off is stored as the magnet-off calibration value OFF c . Furthermore, the difference between the electromagnet when off and when on in north-south polarity is stored N c and the difference between the electromagnet when off and when on in south-north polarity is stored S c . After these calibration values are stored, the microprocessor 24 reconfigures and resets its internal flags for test mode. Since the values obtained in the calibration mode are used as the "normal" values for the oil, a poor calibration oil will cause the test sequence to produce improper results.
The test mode is run by filling the container 10 with the test oil and placing the container in measurement position. The microprocessor 24 then begins running test cycles. After twenty cycles (preferably) have been run in the test mode, the microprocessor 24 stores the mean pulse count obtained between the tenth and the twentieth cycles (preferably) when the electromagnet is turned off as the mean test value M T . This mean value M T is substracted from the similarly obtained calibration value M c and the difference is output to the LCD display 28 as the Corrosion Index R.
R=M.sub.c- M.sub.T Formula 2
Thus, if the test oil contains no corrosion, the mean values obtained in the test and calibration mode will be approximately the same, giving a Corrosion Index R of zero.
This index is a measure of changes in bulk oil chemistry. An increase in this index indicates that the oil is increasingly able to support electrical conduction owing to the presence of polar molecules, moisture, or suspended, charge-bearing particulate. These conditions typically lead to increased wear and corrosion. The most common causes of an increase in this index include thermally accelerated oxidation and nitration, the formation of acids from combustion blow-by in engines, and increased moisture content.
After the twenty-first cycle (preferably), the microprocessor 24 substracts the pulse count taken when the electromagnet is turned off (the magnet-off test value OFF T ) from the mean test value M T , and the difference between the magnet-off calibration value OFF c and the mean calibration value M c is further substracted. The resultant value is output to the LCD 28 as the Contamination Index C.
C=(M.sub.T -Off.sub.T)-(M.sub.c -OFF.sub.c) Formula 3
This index is a measure of the level of oil-insoluble contaminants in the oil as opposed to changes in the bulk oil chemistry. Some common contaminants include water, glycol coolants, metallic wear debris, large insoluble by-products of combustion, and abrasive solids such as road dust. The contamination index value is updated similarly each cycle using the magnet off test value OFF T for each cycle. This method of determining the contamination allows any pulse offsets due to corrosion to be disregarded. Furthermore, the testing for contamination during each cycle allows for the time that it takes for gravity to draw the contaminants into the vicinity of the sensor 16.
FIG. 9 is a plot of the Contamination Index for a series of test samples prepared by introducing known amounts of water into a fresh turbine oil. Again, note the linear relationship between the test data and the known concentrations. The instrument is capable of detecting water at concentrations as low as 100 ppm by weight in light oils. It should be noted that the contamination index is sensitive to the conductivity of a contaminant as well as its concentration. In practice this means that it will assign a higher value to highly corrosive salt water than it will to less damaging clean water. In either case the instrument will detect "free" water as opposed to finely dispersed water.
Beginning at the twenty-first cycle, the difference between the pulse count when the electromagnet 20 is off and the pulse count when the electromagnet 20 is on is determined. This determination is made for the difference when the electromagnet is in both polarities and stored as N T and S T . Similar values obtained from the calibration mode are then substracted from the test mode values with the resultant values outputted to the LCD 28 as the Ferromagnetic debris Index F x .
F.sub.x =(N.sub.c -N.sub.t)+(S.sub.c -S.sub.c) Formula 4
This index is sensitive to conductive, ferromagnetic particles. It increases with particle size, surface conductivity, and debris concentration. The index is primarily sensitive to recent, severe wear of oil-wetted steel and iron parts. This index increases with ferrous wear debris concentration and size.
Similar values may be obtained in succeeding cycles and added to the previous value so that a running total is obtained and displayed.
F.sub.TOT =F.sub.x +F.sub.x'1 Formula 5
Thus, the amount of ferromagnetic debris in the oil is indicated.
FIG. 10 is a plot of the Ferromagnetic Index from a series of tests conducted with a fresh turbine oil contaminated with varying known amounts of 4 to 6 micron iron particles. Note the linear relationship between known content and the index. The instrument will detect iron debris concentrations as low 1 μg/ml.
It should also be noted that this index is sensitive to particle size as well as particle concentrations. For a given concentration this index will increase with particle size. This size sensitivity aids in detecting the large particles produced by abnormal (as opposed to normal) wear.
Another useful index value from the invention is the "OilLife Index"™, OL. This index value is the product of an algorithm which reflects the combined effect of oil degradation and contamination, i.e. when the oil is no longer suitable for continued use due to oxidation or acidity or the presence of corrosive fluids such as glycol or water or the presence of conductive particles. This OilLife Index™ relies upon a 500 cycle data base wherein the median of the last five (496-500 cycle) magnet-off oil calibration values CAL are reduced by the median of the last five (496-500 cycles) magnet-off oil test values TES and the sensor noise value NOS. This summation is divided by a suitable constant, C. ##EQU1##
FIG. 11 graphs the OilLife Index™ value determination respective to percentage of moisture content contaminating two synthetic compressor lubricants. Note will be taken of the Index data linearity on both lubricant examples.
The microprocessor 24 uses pins 148, 150, 152, 154, 156, 158, 160, 162, 164 and 166 to output the index values to the display 28. In the preferred embodiment, LEDs are used as a further indicator of the condition of the oil. The microprocessor 24 sends a signal to a green LED 38a, which is tied to the constant voltage source 50 through a resistor 170. The signal is sent from pin 172 thereby energizing the green LED 38a. If the Corrosion Index, the Contamination Index, the Ferromagnetic debris Index or the OilLife Index™ increases to a significant level, the green LED 38a is de-energized and the yellow LED 38b is energized by a signal from pin 176 of the microprocessor 24 to indicate the need for caution because of a borderline oil sample. The yellow LED 38b is connected to the constant voltage source 50 through a resistor 178. If any of the index values increase to a "high" reading (determined by the designer according to the anticipated application of the device), the yellow LED 38b is de-energized and the microprocessor sends a signal through a pin 180 to energize a red LED 38c, which is connected to the constant voltage source 50 through a resistor 184, to thereby indicate that the oil sample is "bad." In the event that a pulse count reading produced by the sensor for any condition of electromagnet 20 drops to a level that would indicate a shorting of the sensor due to large amounts of water or debris, the red LED 38c will be pulsed and the word "CRITICAL" will be sent to the display 28.
In the preferred embodiment, the microprocessor 24 receives the pulse counts for 100 cycles and then stops if the Contamination index and the Ferromagnetic debris index values remain very small. However, if the Contamination or Ferromagnetic debris indicates an appreciable amount of deterioration in the oil, the microprocessor continues receiving for 500 cycles to determine the full amount of the contaminants. The word "FINISHED" will be sent to the display 28 when the microprocessor 24 completes its readings.
The microprocessor checks for a high reading on pin 186 to determine if the test should be aborted. Aborting occurs by pressing the test button while in test mode. The pin 186 is connected to the constant voltage source 50 through a resistor 188 and to the test button 37 which connects to ground when pressed, thereby allowing the line to be driven high.
The microprocessor controls the polarity and the power to the electromagnet 20 by output signals from pins 202 and 204 which are connected to pins 76b and 78b of the connector port 74b. Thus, the signals are transferred along the shielded serial cable 34 to the connector port 74a of the test box 30. A low signal generated on both pins 202 and 204 will force the electromagnet 20 into its "off" mode. A high signal generated upon pin 202, while a low signal is generated on 204, will force the electromagnet into the "on" mode in north-south polarity. Finally, a high signal generated upon pin 204, while a low signal is generated on pin 202, will force the electromagnet into the "on" mode in south-north polarity.
A reset circuit 206 including resistors 208 and 210 connected to capacitors 212 and 214 is attached to the constant voltage source 50 and acts to pull up the input voltage to five volts after the supply contact is made. The reset circuit 206 is attached to pins 216, 218 and 220 of the microprocessor 24, thereby assuring that the internal reset of the microprocessor is working properly.
In the preferred embodiment, a beeper alarm 222 is used for signaling the presence of dangerous levels of deterioration and contamination in the test oil. The beeper 222 is attached through a capacitor 224 to a pin 226 of the microprocessor 24.
The connector port 74b has a pin 124b connected to a probe ground wire 228 which is connected to a power clip 230 for hook up to an external power source. The switch 39 engages the external power source when depressed thereby powering the electromagnet voltage supply 23. The switch 39 is further connected to a voltage regulator 232 which regulates the voltage to five volts for supplying the constant voltage source 50 which powers the digital requirements of the system. The electromagnet voltage supply 23 is connected to the probe ground wire 228 through resistor 234, and the constant voltage source 50 is similarly connected to the ground wire 228 through resistor 236.
The connector port 74b has pins 126b and 130b connected to ground. The connector port 74b further has pin 132b connected to the electromagnet voltage supply 23.
At the conclusion of a foregoing test sequence, the accumulated debris and wear particles may be viewed directly for analysis and direct interpretation for type and origin. FIG. 11 illustrates a suitable viewing apparatus for this purpose which comprises a microscope 11 having an optics tube 13 that is axially slidable within an open bottom support base 15. Focal adjustment of the optic tube is made by rotation of the adjustment knob 17. A wall opening 19 in the support base 15 permits the microscope viewing area 21 at the bottom of base 15 to be illuminated by a lamp such as battery powered penlight 25. The support base bottom is sized to cover or fit in or over the sensor 16 so as to place the contaminant deposition surface of the sensor 16 in the microscope viewing area 21.
Reversing the procedure for connectively sealing the sample container 10 to the sensor 16, the unit is gently inverted from the test position to drain the oil sample away from the container mouth 12 interface with the sensor 16. This inverting process is carried out with such care as to avoid disruption of the contaminant deposition pattern on the sensor 16. Oil surface tension and presence of the permanent magnet 18 field is normally sufficient to secure the contaminant pattern during a careful inversion.
With the oil sample fluids drained from the container 10 mouth opening 12, the seal between the container and the sensor may be separated and the container 10 confined sample fluids removed from the sensor 16 unit leaving the accumulated deposits of contaminant particles exposed openly on the sensor deposition surface.
Without flushing the contaminant deposits from the sensor 16 surface or otherwise disrupting the deposition pattern, the sensor 16 is re-erected and the microscope 11 positioned with the base 15 placed over or connected to the sensor 16 whereby the sensor surface plane coincides with the microscope 11 viewing area 21. In this condition and disposition, the contaminant particle deposition patterns and organization may be visually scrutinized and analyzed under different lighting and stimulation conditions.
For example, the deposits may be viewed under the illumination of spectrally restricted light such as violet, red or yellow. Similarly, an optic tube 13 eyepiece filter may be positioned to accomplish similar results. Additionally, a camera may be connected to the optic tube to photograph the deposits on video tape or spectrally specific film. Moreover, in this exposed disposition, the electromagnet 20 may be actuated to stimulate movement of the magnetically responsive particles thereby revealing their unique classification patterns which conform to the permanent magnet flux lines. In the presently preferred embodiment of the invention, these flux lines are revealed in two or three concentric circles of clustered magnetic material deposited on the sensor 16 surface. These magnetically responsive and geometrically distributed particles will physically move in alternating unison to the magnetic field pole reversals. Randomly distributed non-magnetic material has no response to the presence or absence of the alternating magnetic field.
Using a 100× power microscope, this technique has been used to observe particles as small as 1.0 microns. Without the microscope, but with the electromagnetic motion enhancement, only particles larger than about 40 microns may be directly observed.
This visual information may reveal the extent of damage occurring to a machine as well as the cause. Most wear particles in a lubricant result from three root causes: adhesive wear, abrasive wear or metal fatigue.
Adhesive wear is that which results from sliding, scuffing, or rubbing contact between surfaces. Sliding type adhesive wear is common and quite normal wear which takes place for most applications. Scuffing and rubbing are not normal.
Normal adhesive wear generates very small (0.1 to 5 microns) wear particles as high spots are sheared down. Abnormal adhesion (result of scuffing or rubbing) may generate much larger particles.
Abrasive wear is the cutting action normally caused as hard particles gouge out long (10 to several 100 microns) and sometimes curled strips of metal. Sand or metal wear particles are frequently the cause of abrasive wear. Abrasive wear particles get broken into smaller pieces as they are milled by the gears.
Fatigue (also called "high cycle fatigue") occurs when the metal surfaces fail due to repeated cyclic loading. This is commonly seen on gear teeth and rolling element bearings.
Fatigue particles tend to be relatively large (10 to 20 microns) having blocky or spherical shape. The presence of spherical particles usually is a very strong indication of fatigue failure. These particles are generated when sub-surface cracks allow a chunk of material to break free which then rolls around. When the surface connected cracks join to release a blocky surface particle, the sub-surface spherical particles are released.
In a different mode of analysis, oil contamination deposits on the sensor surface may be transferred from the original accumulation surface to a separate, analyzing surface having, for example, greater electromagnetic field strength or complex illumination or light filter capacities. In this analysis mode, the deposits are bodily transferred in their originally deposited organization by means of a blotter or slide supported adhesive gel. By foregoing the capacitance measuring function of the invention, the deposition surface of the sensor 16 may be covered with a transfer sheet such as a filter paper or transparent film as a direct deposition surface to lift the contaminant specimen bodily intact from the sensor 16 with a minimum of magnetic classification disturbance.
Given these enhanced visual insights into the cause of wear particles in the oil as isolated by the invention, the maintenance and operations personnel may choose and pursue the correct follow up actions. For instance, after detecting abrasive wear particles, the oil and filter should be changed. Seals and air filters should be inspected to determine how sand or dirt might be getting into the tube system. Similar logical actions can be derived for the other forms of wear.
Direct visual observation of mechanical wear particles makes it easy for equipment maintenance people to "see" what is taking place in the lubricated system. A magnified 100× view of wear particles and other debris makes it much easier to solve root causes of lube system problems.
Although a preferred embodiment is described herein, it will be understood that the invention is capable of numerous modifications, rearrangements and substitutions of parts without departing from the scope of the invention as defined in the following claims. For example, particular oil borne contaminants have substantially unique, frequency dependent dielectric properties that may be identified by incremental or sweep variations in the sensor 16 input signal frequency. Useful data may also be acquired by measuring the phase shift of a sensor 16 signal in the microwave frequency range.
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A method and apparatus for detecting the degree of deterioration in lubricating oil including a grid-like capacitive sensor, that uses the lubricating oil as a dielectric medium, and a magnetic field imposed upon the oil to attract ferromagnetic wear particles into the vicinity of the sensor. Preferably, the magnetic field is generated by a permanent magnet and an electromagnet aligned such that the magnetic field produced by each magnet acts upon the oil along the same axis. A plurality of capacitance measurements are taken at periodic intervals for one type of classification and analysis. Magnetically induced particle concentrations are analyzed visually under the aid of periodic magnetic flux reorientation and optical magnification.
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BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention generally relates to coding digital video images, and more particularly to reducing loss of image information by automatically adjusting operating parameters utilized in the coding process.
[0003] 2. Description of Background Art
[0004] Digital video systems are becoming increasingly popular, especially in business settings. An example application of a digital video system is a teleconferencing system. Despite their popularity, digital video systems can be extremely expensive in terms of storage and communication costs. The cost of storage and communication is driven by the massive quantity of digital image data which is generated by the system.
[0005] One way to reduce costs or improve performance is to reduce the quantity of digital data used to represent images. Various well known compression techniques have been utilized to reduce the quantity of data used to represent a digitized image. While image compression may reduce some of the costs associated with handling digital image data, the downside is that image quality may suffer.
[0006] A number of compression techniques conventionally involve linear transformation of the digital image, followed by quantization, and coding of transform coefficients. In this way, the quantized and coded signals may be compressed, transmitted, or stored, and subsequently decompressed using an inverse set of operations.
[0007] The Discrete Cosine Transform (DCT) has commonly been used for image compression and decompression. However, because such DCT-based image processing is computationally intensive, various methods have been devised to improve the performance of the transform process.
[0008] The DCT process involves computing a set of coefficients to represent the digital image. One approach used to reduce the time required to perform the transform process is to compute only a subset of the coefficients. The selection of the particular subset of coefficients to be computed is based on detected characteristics of the digital image. While yielding acceptable results, the prior art process of classifying a digital image according to its characteristics and then selecting a subset of coefficients has no mechanism to measure the quality of the transformed image. Furthermore, the selection criteria used to classify an image are fixed such that they cannot be easily adjusted to improve image quality.
[0009] Therefore, to improve the quality of compressed digital images what is needed is a coding system having self-adjusting selection criteria for selecting a transform function.
SUMMARY OF THE INVENTION
[0010] The invention monitors the quality of coded digital images, and based on the monitored quality of the images, updates operating parameters that are used in coding the images.
[0011] A set of predetermined coding functions is available in a video coding system to code a digitized video image. One of the coding functions is selected and applied to the input image. The selection of the coding function is made based upon measured characteristics of the input image and selection criteria which are applied to the measured characteristics. The image is then decoded and the quality of the decoded image is measured. The selection criteria are updated based on the measured quality of the decoded image, whereby for subsequent images coding functions are selected to produce images with a higher quality measure.
[0012] In another aspect of the invention, an historical record is made for the measured characteristics of the images processed by the system. The measured characteristics are correlated with the selected coding function. Periodically, the selection criteria are updated based on the historical record. The historical record provides a broad perspective upon which updating of the selection criteria is based.
[0013] The invention further selects one of a predetermined set of transform functions to code an image. An inverse transform function is selected, independent of the selection of the first transform function, whose application minimally covers the image produced by application of the first transform function. The inverse transform function is then applied to the image, the quality is measured, and the selection criteria are updated as described above. The updating of the selection criteria enables selection of a suitable transform function.
[0014] In still another aspect of the invention, the selection criteria include adjustable thresholds and comparisons of them to measured characteristics of the image to be coded. The measured characteristics are correlated to the selected inverse transform function in the historical record. The respective thresholds are then updated from the historical record of the measured characteristics.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] [0015]FIG. 1 is a block diagram of a computer system for encoding video sequences;
[0016] [0016]FIG. 2 is a block diagram of a prior art video coding system;
[0017] [0017]FIG. 3 is a block diagram of a video coding system which utilizes the present invention;
[0018] [0018]FIG. 4 shows the relationship between FIGS. 4A and 4B which together contain a flowchart of the processing performed by the video coding system in utilizing the present invention;
[0019] [0019]FIG. 5 shows the EnergyThresholdArray memory map;
[0020] [0020]FIG. 6 shows the memory map of a block which is output after the application of the Four-by-Four block transform function;
[0021] [0021]FIG. 7 illustrates the memory map of the Decoded Block Quality Array; and
[0022] [0022]FIG. 8 illustrates the memory map of the Total Energy histogram.
DETAILED DESCRIPTION
[0023] [0023]FIG. 1 is a block diagram of a computer system 100 for encoding video sequences. The exemplary system 100 is a Power Macintosh which is available from Apple Computer, Inc. The system includes a central processing unit (CPU) 102 , an input device 104 such as a keyboard or a mouse, and an output device 106 such as a computer monitor. The system 100 further includes data storage 108 which may consist of magnetic disks and/or tapes, optical storage, or various electronic storage media. The RAM 110 is available for storage of program instructions and data as referenced by the CPU 102 . The functional units of the system 100 are interconnected by a signal bus 112 .
[0024] An operating system program 114 is shown as stored in the RAM 110 to indicate that the program is executable by the CPU 102 , even though only portions of the program may be present in the RAM at a given time. The operating system 114 controls allocation of the resources which are available in the system 100 .
[0025] The system 100 further includes a video input device 116 which is coupled to the bus 112 . The video input device 116 captures and digitizes frames of images presented to a camera portion of the video input device 116 . The video coding system program 118 , represented as being stored in the RAM 110 , compresses the frames of data input by the video input device 116 . The compressed frames may then, depending upon the application, be either stored on the data storage 108 as video frames 120 , or output to a receiving application via the network input/output device 122 .
[0026] [0026]FIG. 2 is a block diagram of a prior art video coding system 150 . The video coding system 150 has program modules comprising a color converter 152 , a motion estimator 154 , a transform processor 156 , a classifier 158 , a quantization processor 160 , a lossless coder 162 , an inverse quantization processor 164 , an inverse transform processor 166 , and a motion compensator 168 , the latter three of which provide feedback data to the motion Estimator 154 .
[0027] The color converter 152 receives a frame of a digitized video image via input line 170 and converts the frame from Red-Green-Blue (RGB) format to a luminance-chrominance format such as Yuv. The converted frame is provided as input to a summation element 172 . The second input to the summation element 172 is provided by the motion estimator 154 .
[0028] The motion estimator 154 receives as input a frame from color converter 152 as shown by Line 174 . The previously processed frame is also input to the motion estimator 154 as shown by line 176 . The motion estimator 154 compares the frames to estimate the movement of portions of the image in the frame. The output of the motion estimator 154 is provided to the summation element 172 which outputs a residual frame on line 178 to the transform processor 156 . The residual frame is essentially the difference between the present frame as input on line 174 and the previous frame as input on line 176 .
[0029] The transform processor 156 receives the residual frame from the summation element 172 . The input frame is processed one block at a time, where a block is an m×n array of elements of the input frame. Each element of the block represents a pixel of data In the exemplary embodiment the block size is an 8×8 array of pixel data. The input frame is also input to the classifier 158 via line 178 .
[0030] The transform processor 156 applies a Discrete Cosine Transform function to the input block to obtain an output block of coefficients. Background material on transform coding of images may be found in Transform Coding of Images , R. J. Clarke, Academic Press (London), 1985. To save computation time, the transform processor 156 , based on a selection made by the classifier 158 , may compute only a subset of the coefficients of the block. The classifier 158 determines characteristics of the input block, and based on predetermined selection criteria, selects for computation a subset of the coefficients of the block. Note, however, that a block having certain characteristics will result in the computation of all coefficients of a block. The selected subset of coefficients to compute is input to the transform processor 156 as shown by line 182 . The selected subset of coefficients which is selected for computation is hereinafter referred to as the “transform function” or “transform type.”
[0031] Each block of coefficients output by the transform processor 156 is input on line 184 to the quantization processor 160 . The quantization processor 160 reduces the number of bits required to represent each of the coefficients in the block by dividing each coefficient by a predetermined constant The predetermined constant is selected based on the application's required bit transmission rate.
[0032] The block of quantized coefficients is input on line 186 to the lossless coder 162 . The lossless coder 162 codes the block and outputs the coded information on line 188 for storage to data storage 108 , output on network input/output 122 , or output to output device 106 .
[0033] The block of quantized coefficients is also provided as feedback on line 190 to the inverse quantization processor 164 , to the inverse transform processor 166 , and to the motion compensator 168 . The purpose of the feedback data is to permit the motion estimator 154 to perform its estimation by comparing a newly input frame to a frame of the previous image as viewed by an application receiving the output of lossless coder 162 .
[0034] The inverse quantizer 164 multiplies each coefficient of the input quantized block by the same predetermined constant that was used by the quantization processor 160 . The output of the inverse quantizer 164 is provided via line 192 as input to the inverse transform processor 166 .
[0035] The inverse transform processor 166 performs the inverse of the transform function performed by the transform processor 156 and as indicated by the classifier 158 on line 194 . The motion compensator 168 obtains the block of pixels from the previously decoded image which is offset by the motion vectors from the block of interest. The summation element 196 performs a pixel-wise addition of the output of the motion estimator 154 with the incoming block.
[0036] [0036]FIG. 3 is a block diagram of a video coding system 300 which utilizes the present invention. The elements added to FIG. 2 in FIG. 3 include a forward classifier 302 , a classifier feedback processor 304 , a quality measurement processor 306 , and an inverse classifier 308 .
[0037] The forward classifier 302 selects a transform type, which is indicative of a selectable transform function, based on the characteristics of the block input on line 180 and adjustable selection criteria as provided by the classifier feedback processor 304 on line 310 . Recall from FIG. 2 that the selectable transform function is an indication of the subset of coefficients to compute for the input block. The transform type is input on line 312 to the transform processor 156 .
[0038] The classifier feedback processor 304 provides selection criteria on line 310 to the forward classifier 302 . The selection criteria are adjusted by the classifier feedback processor 304 based on various input data, including: (1) from the forward classifier 302 , the transform type and characteristic values computed for a block as shown by line 314 ; (2) from the quantization processor 160 , the quantization value, Q, on line 316 ; (3) from the motion estimator 154 , motion vectors on line 318 ; (4) from the quality measurement processor 306 , a Peak Signal to Noise Ratio (PSNR) on line 320 ; and (5) from the inverse classifier, an inverse transform type on line 322 . The processing performed by the classifier feedback processor is explained further in the discussion pertaining to the FIGS. that follow.
[0039] Generally, the quality measurement processor 306 measures the quality of the coded images produced by the video coding system 118 for the purpose of improving the quality of subsequent images coded by the system 118 . The quality measurement processor 306 does so by indicating to the classifier feedback processor 304 the PSNR of a block which has been coded and then decoded, relative to the block input for coding. The processing performed by the quality measurement processor 306 is explained further in the discussion pertaining to the FIGs. that follow.
[0040] The inverse classifier 308 selects an inverse transform function for input on line 322 to the classifier feedback processor 304 and for input on line 324 to the inverse transform processor 166 . The inverse classifier 308 selects an inverse transform type independent of the classification performed by the forward classifier 302 . The purpose of the independent selection is decode the block so that the selection criteria used by the forward classifier 302 may be adjusted to improve the image quality of the block output by the transform processor 156 . The processing performed by the inverse classifier 308 is explained further in the discussion pertaining to the FIGs. that follow.
[0041] [0041]FIG. 4 shows the relationship between FIGS. 4A and 4B which together form a flowchart of the processing performed by the video coding system 300 in utilizing the present invention.
[0042] In Step 402 , the video coding system 300 performs initialization by associating predetermined transform functions with image characteristics and selection criteria. FIG. 5 illustrates how the associations are established in the exemplary system. Briefly, the types of image characteristics and selection criteria utilized include adjustable thresholds of overall energy, horizontal high pass energy, vertical high pass energy, and motion vector magnitudes. The adjustable thresholds and usage thereof are explained in more detail below.
[0043] Step 404 receives an input block whose motion vector has been estimated by the Motion Estimator 154 . A motion vector consists of an x value and a y value, where x is the movement of the image in the block on an x-axis and y is the movement of the image in the block block on a y-axis. The input block is received by the transform processor 156 and the forward classifier 302 , and the motion vector is received by the classifier feedback processor 304 .
[0044] The pseudocode in Table 1 below corresponds to steps 406 and 408 .
TABLE 1 001 ForwardClassification( Q, InputBlock, MotionVectors ) 002 begin 003 004 // Compute characteristics of the input block. 005 energy = ComputeEnergy( InputBlock ); 006 hHPenergy = ComputeHorizHighPassEnergy( InputBlock ); 007 vHPenergy = ComputeVertHighPassEnergy( InputBlock ); 008 mvMag = ComputeMotionVectorMagnitude( MotionVectors ); 009 010 // Loop through each transform type. 011 for transformType = 1:NumberOfTransformTypeTypes-1 012 013 // Select proper thresholds. 014 threshEnergy = EnergyThresholdArray[transformType][Q]; 015 threshHHP = HorizHighPassEnergyThresholdArray[transformType][Q]; 016 threshVHP = VertHighPassEnergyThresholdArray[transformType][Q]; 017 threshMV = MotionVectorMagnitudeThresholdArray[transformType][Q]; 018 019 if energy < threshEnergy and 020 hHPenergy < threshHHP and 021 vHPenergy < threshVHP and 022 mvMag < threshMV 023 then 024 return transformType; 025 end 026 end 027 028 // Since none of the previous transform types work, 029 // select the most general transform type. 030 return DefaultTransformType; 031 032 end
[0045] At step 406 , characteristic values are computed for the input block. Lines 5-8 of the pseudocode compute the respective values according to formulae set forth below:
[0046] The total energy is the image energy and is computed as the sum of the absolute pixel values. Specifically, where i and j form an index into the input block, x:
total energy=Σ (i,j)∈block |x ( i,j )|
[0047] The horizontal high pass energy is computed as the sum of absolute differences of horizontally adjacent pixel values. Specifically:
hHPenergy=Σ 0≦i<Blockwidth−1, 0≦j<BlockHeight |x ( i, j )− x ( i +1 ,j )|
[0048] The vertical high pass energy is computed as the sum of the absolute differences of vertically adjacent pixel values. Specifically:
vHPenergy=Σ 0≦i<Blockwidth, 0≦j<BlockHeight−1 |x ( i, j )− x ( i,j +1)|
[0049] The motion vector magnitude may be computed as either the sum of the squares of each component, or as the maximum of the two vector components. In the exemplary embodiment either calculation is suitable. Specifically:
mvMag= x 2 +y 2 or
[0050] mvMag=max(x, y)
[0051] Lines 10-30 of the pseudocode of Table 1 correspond to step 408 . Step 408 selects a transform function based on the selection criteria set specified in lines 19-25.
[0052] [0052]FIG. 5 shows the EnergyThresholdArray memory map. The memory maps for the HorizHighPassEnergyThresholdArray, the VertHighPassEnergyThresholdArray, and the MotionVectorMagnitudeThresholds are similar in character to the EnergyThresholdArray of FIG. 5. Therefore, for brevity only the EnergyThresholdArray is illustrated.
[0053] Each of the arrays has t rows, each representing a different transform function, and columns 1-MAX_Q which represent the constants used by the quantization processor 160 . MAX_Q is a predetermined constant. Each entry in the respective arrays is initially zero, and, during the course of processing is updated by the classifier feedback processor 304 .
[0054] The transform functions utilized in the exemplary system include Zero-block, One-by-Three, Four-by-Four, Four-by-Eight, and Eight-by-Eight.
[0055] [0055]FIG. 6 shows the memory map of a block which is output after the application of the Four-by-Four block transform function. The transform processor 156 computes the coefficients for the upper-left four rows and four columns of the block. The computed coefficients are designated as C ij in the array. The remaining entries in the array are set to zero.
[0056] The Zero-block transform function results in the transform processor 156 setting every entry in the output block to zero. The One-by-Three transform function results in the transform processor 156 computing the coefficients for the first three columns of row one of the input block, and setting the remaining entries to zero. The Four-by-Eight transform function results in the transform processor 156 computing the coefficients for all eight columns of the first four rows of the input block, and setting the remaining entries to zero. The Eight-by-Eight transform function results in the transform processor 156 computing the coefficients for all eight rows and eight columns of the input block. Note that the Eight-by-Eight transform function is the DefaultTransformType as returned by the ForwardClassification pseudocode of Table 1.
[0057] Returning now to FIG. 4A, the transform processor 156 performs step 410 in applying to the input block the transform function selected by the forward classifier 302 . The quantization processor 160 performs Step 412 in quantizing the block received from the transform processor 156 . Control is directed via path 412 p to steps 414 and 416 of FIG. 4B. At step 414 , the lossless coder 162 codes the block and outputs the block to data storage 108 or network input/output 122 .
[0058] Step 416 is performed by the inverse classifier 308 . The pseudocode in Table 2 below sets forth the processing for selecting a transform function that minimally covers the coefficients of the input quantized block.
TABLE 2 001 InverseClassification( QuantizedCoefficientBlock ) 002 begin 003 004 // Determine the locations of the non-zero coefficients. 005 locOfNonZeroCoef 006 = DetermineLocationOfForNonZeroCoefs(QuantizedCoefficientBlock ); 007 008 // Find the transform whose set of coefficients minimally cover the non-zero 009 // coefficints 010 transformType = FindMinimalCoveringTransform( locOfNonZeroCoef ); 011 012 return transformType; 013 014 end
[0059] At lines 5-6 of the InverseClassification pseudocode, the locations of the non-zero entries in the quantized block are identified. Line 10 identifies the inverse transform function (e.g., Zero-by-Zero, One-by-Three, Four-by-Four, Four-by-Eight, or Eight-by-Eight) whose application results in computing all coefficients for the input quantized block and which defines the smallest portion of the 8×8 block (e.g., Zero-by-Zero<One-by-Three<Four-by-Four<Four-by-Eight<Eight-by-Eight).
[0060] The inverse quantization processor 164 inversely quantizes the quantized block at step 418 . Processing continues at step 420 where the inverse transform processor 166 applies the inverse of the transform function selected by the inverse classifier 308 . The decoding process continues at step 422 where the motion compensator 168 undoes the motion estimation applied by the motion estimator 154 .
[0061] The quality measurement processor 306 measures the quality of the decoded block at Step 424 . The exemplary system uses the following calculation to measure decoded block quality (Note that x is the decoded block and {circumflex over (x)} is the original input block):
[0062] [0062] PSNR = 10 log ( ∑ ( i , j ) ∈ block ( x ( i , j ) - x ^ ( i , j ) ) 2 blocksize * 255 2 )
[0063] The quality measurement processor 306 keeps an historical record of decoded block quality values and outputs the decoded block quality on line 320 to the classifier feedback processor 304 .
[0064] [0064]FIG. 7 illustrates the memory map of the Decoded Block Quality Array in which historical records of decoded block quality values are kept. For each transform function/quantizer value pair, a historical record is kept of the decoded block quality values. The decoded block quality value may be the average of the PSNR values, the median of the PSNR values, the maximum of thePSNR values, or another suitable statistical measure of the PSNR values. The particular statistical function chosen is driven by application requirements.
[0065] Returning to FIG. 4B, Steps 426 and 428 are performed by the classifier feedback processor 304 . The classifier feedback processor 304 maintains an historical record of characteristic values and quality measures of decoded blocks, as related to the applied inverse transform function applied by the inverse transform processor 166 . At step 426 the historical record is updated. The pseudocode in Table 3 below sets forth the processing for updating the historical record.
TABLE 3 001 procedure UpdateHistograms 002 ( 003 InputBlkCharHist[NumberOfInputBlkCharTypes][NumberOfTransformTypes][MAX_Q], 004 InputBlkCharType, 005 InverseTransformType, 006 Q, 007 ForwardTransformType, 008 InputBlkCharValue, // Comes from the forward classifier. 009 ) 010 011 begin 012 013 // The array ‘NumberOfComputedCoefficients’ is a constant global array. 014 NumCoefInverse = NumberOfComputedCoefficients[InverseTransformType]; 015 NumCoefForward = NumberOfComputedCoefficients[ForwardTransformType]; 016 017 if NumCoefInverse > SomeNiceConstant * NumCoefForward 018 019 // Select the histogram to update. 020 theHistogram = InputBlkCharHist[InputBlkCharType][InverseTransformType][Q] 021 022 // Update the histogram. 023 theHistogram[InputBlkCharValue]++; 024 025 end 026 027 end
[0066] Inputs to the procedure, UpdateHistograms, include: (1) a histogram designated as InputBLkCharHist [NumberofInputCharTypes][NumberOfTransformTypes][MAX_Q]; (2) a characteristic designated as InputBlkCharType; (3) the inverse transform function designated as InverseTransformType; (4) the quantization value Q; (5) the forward transform function designated as ForwardTranformType; and (6) an input characteristic value designated as InputBlkCharValue.
[0067] [0067]FIG. 8 illustrates the memory map of the Total Energy Histogram 472 . The memory maps of the Horizontal High Pass Energy Histogram, the Vertical High Pass Energy Histogram, the Motion Vector Magnitude Histogram are similar in character to the Total Energy Histogram. Therefore, for brevity only the Total Energy Histogram is illustrated. Each of the histograms is singly input to the UpdateHistograms procedure of Table 3 as shown by line 3 of the pseudocode.
[0068] Each of the histograms has a row for each of the available transform functions, and a column for each value in the range of quantization values. Each entry in the array references a one-dimensional array having indices ranging from 0 to a predetermined maximum value. Values in the one-dimensional array are updated as defined by the UpdateHistograms pseudocode of Table 3. The InputBlkCharType which is input to the UpdateHistograms pseudocode specifies which histogram to update.
[0069] Returning now to FIG. 4B, at Step 428 the classifier Feedback processor 304 periodically adjusts the selection criteria used by the forward classifier 302 and then returns control, via control path 428 p , to step 402 to process the next block. In the exemplary embodiment, the selection criteria are adjusted once per second.
[0070] The procedure UpdateThresholds, as set forth in the pseudocode of Table 4 below, updates the selection criteria by selectively updating the various thresholds in the EnergyThresholdArray (FIG. 5), the HorizHighPassEnergyArray, the VertHighPassEnergyArray, and the MotionVectorMagnitudeArray.
TABLE 4 001 procedure UpdateThresholds 002 ( 003 004 InputBlkCharThresh[NumberOfInputBlkCharTypes][NumberOfTransformTypes][MAX_Q], 005 InputBlkCharHist[NumberOfInputBlkCharTypes][NumberOfTransformTypes][MAX_Q], 006 DecodedBlockQuality[[NumberOfTransformTypes][MAX_Q], 007 ) 008 009 begin 010 011 // Loop through each transform type. 012 for TransformType = 1:NumberOfTransformTypes 013 014 // Loop through each quantizer value. 015 for Q = 1:MaxQ 016 017 // Loop through each input block characteristic type 018 for InputBlkCharType = 1:NumberOfInputBlkCharTypes 019 020 // Select the Order-Statistic type. 021 OrderStatisticType = 022 SelectOrderStatistic 023 ( 024 InverseTransformType, 025 Q, 026 InputBlkCharType, 027 DecodedBlockQuality[TransformType][Q] 028 ); 029 030 // Compute the updated threshold. 031 InputBlkCharThresh[InputBlkCharType][ TransformType][Q] = 032 OrderStatistic 033 ( 034 orderStatisticType, 035 InputBlkCharHist[InputBlkCharType][TransformType][Q] 036 ); 037 038 end 039 end 040 end 041 042 end
[0071] The inputs to the procedure are listed in lines 4-6. The input parameter at line 4 references the threshold arrays (See FIG. 5); the input at line 5 references the corresponding histograms (See FIG. 8); and the input at line 6 references the Decoded Block Quality Array (See FIG. 7).
[0072] As set forth in lines 12-40, each of the threshold arrays is updated by first selecting an order statistic to apply to the respective histogram, and then applying the selected order statistic to the respective histogram. The OrderStatistic function which is initiated on lines 31-36 applies the orderStatisticType to the referenced histogram of characteristic values. The orderStatisticType is a percentage, and the OrderStatistic function computes the characteristic value. To compute the characteristic value, the number of occurrences for all the characteristic values are totaled, and the total is multiplied by the orderStatisticType to obtain an adjusted occurrence total. Then, beginning at the lowest characteristic value in the histogram and proceeding with the following characteristic values, the number of occurrences are totaled until the adjusted occurrence total is reached. The OrderStatistic function then returns the characteristic value at which the adjusted occurrence total was reached.
[0073] The pseudocode for the function SelectOrderStatistic is set forth in Table 5 below.
TABLE 5 001 function SelectOrderStatistic 002 ( 003 TransformType, 004 Q, 005 InputBlkCharType, 006 DecodedBlockQuality 007 ) 008 009 begin 010 011 // The array ‘NumberOfComputedCoefficients’ is a constant global array. 012 NumCoef = NumberOfComputedCoefficients[TransformType]; 013 014 // Depending on the measure being used, select the OrderStatisticType. 015 // Constants k1-k4 are predetermined. 016 case InputBlkCharType of 017 begin 018 Energy: OrderStatisticType = k1*NumCoef*DecodedBlockQuality; 019 HorizHPEnergy: OrderStatisticType = k2*NumCoef*DecodedBlockQuality; 020 VertHPEnergy: OrderStatisticType = k3*Numcoef*DecodedBlockQuality; 021 MVMagnitude: OrderStatisticType = k4*NumCoef*DecodedBlockQuality; 022 end 023 024 return OrderStatisticType; 025 026 end
[0074] The inputs to the SelectOrderStatistic function are set forth in lines 3-6. The inputs are the transform type, the quantization value, a characteristic type, and a value that indicates the quality of the decoded block.
[0075] The function SelectOrderStatistic returns an OrderStatisticType based upon the input characteristic type, a predetermined constant, the number of coefficients computed for the input transform type, and the input quality value.
[0076] While the foregoing exemplary embodiment of the invention is described in terms of a software implementation, those skilled in the art will recognize that the invention could also be implemented using logic circuits. The exemplary embodiments described herein are for purposes of illustration and are not intended to be limiting. Therefore, those skilled in the art will recognize that other embodiments could be practiced without departing from the scope and spirit of the claims set forth below.
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In a digital signal processing system, a method for selecting a transform function to apply to an input signal based on characteristics of the signal, and for self-adjusting criteria which are used in selecting a transform function to apply to a subsequent signal. Characteristics are obtained from the signal. The characteristics are compared to adjustable criteria which are used in selecting a transform function. Differing criteria are maintained for the different selectable transform functions. A record is maintained of transform functions selected and the particular characteristics that caused the selection. Based on the ability of a transform function to minimally define the coded signal, an inverse transform function is selected to decode the signal. The criteria used in selecting a transform function to apply to a subsequent signal are adjusted based on a quality measure of the decoded signal and the record of selected transform functions.
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FIELD OF THE INVENTION
The present invention relates to a light scattering particle size distribution measuring apparatus, which irradiates a material sample with light from a light source, and measures the size distribution of particles in the sample on the basis of a scattered light intensity pattern obtained thereat.
DESCRIPTION OF THE PRIOR ART
Systems capable of measuring the size distribution of particles within a sample of material are useful in a plurality of fields. FIG. 7 shows a schematic of a prior art scattering particle size distribution measuring apparatus system. As shown in FIG. 7, the system comprises a light source 71 , capable of emitting laser light 72 . In addition, a shutter 73 , comprising a shutter member 73 a and a shutter driving member 73 b , is used to modulate the laser light 72 . A beam expander 74 expands the laser light 72 prior to incurring a flow through cell 75 containing a material sample 76 . Thereafter, a condenser lens 77 is used to focus the light onto a photodetector 78 which detects the scattered and transmitted light from the condensor lens 77 . Commonly, a multiplexer 79 , which is in communication with a CPU 80 , captures the signal from the photodetector 78 upon the detection of light. The CPU 80 may be programmed with various algorithms and other mathematical formulae to permit arithmetic computations of scattering based on the light intensity pattern received at the photodetector 78 . A personal computer 81 , in communication with a display terminal 82 , may be used to control the overall system.
In the foregoing system, when a cell 75 containing a material sample 76 is irradiated with laser light 72 , a portion of light is scattered by particles within the material sample 76 , and a portion of the light is transmitted through the material without a scattering effect.
A problem associated with prior art systems requires the optical axis of a photodetector 78 be held exactly coincident with that of a light source 71 . More specifically, the center of an axis of laser light 72 emitted from a light source 71 is required to be coincident with a center of a light receiving device of the photodetector 78 . Commonly, the foregoing axis become misaligned due to the thermal deformation of the light source 71 , the thermal deformation of the optical bench, thermal deformations in the cell 75 , condenser lens 76 , or photodetector 78 .
In an effort to correct the foregoing misalignment issues, conventional particle size distribution measuring systems having utilized optical stages 83 , commonly referred to as X-Y stages, to maintain the optical axis. As shown in FIG. 7, the X-Y stage moves a photodetector 78 in parallel, and corrects the foregoing misalignment of the optical axis. To correct a misalignment, the operator is required to manually actuate the direct acting actuator 85 , to correct misalignment along the X axis, or the direct acting actuator 84 , to correct a misalignment along the Y axis. Generally, the direct acting actuators 84 and 85 , respectively, having included piezoelectric devices or a stepping motor.
The above-referenced optical axis adjustment work is required to be performed for every measurement and takes several minutes for each adjustment. As such, it has been required for an operator to expend considerable time and effort for each measurement. In addition, inaccurate measurements could occur should there be a time lag between the optical axis adjustment work and the measuring operation due to a plurality of factors, such as, for example, vibrations, changes in temperature, or other environmental conditions.
The present invention has been made in view of the foregoing matters, and an object of the present invention is to provide a light scattering particle size distribution measuring apparatus which does not require a burdensome optical axis adjustment of operator for every measurement, thereby maintaining a state most suitable for measuring.
SUMMARY OF THE INVENTION
To achieve the above object, the present invention discloses a light scattering particle size distribution measuring apparatus which irradiates a sample with light from a light source, detects the resulting scattered light from the sample by a photodetector, and measures the size distribution of particles in the sample on the basis of a scattered light intensity pattern obtained. More specifically, the present invention comprises an automatic adjustment mechanism which aligns and maintains a central position of the foregoing photodetector with a central position of the foregoing light source is provided.
In another embodiment, a light scattering particle size distribution measuring apparatus is provided comprising an optical axis adjustment mechanism capable of automatically adjusting the central positions of the light source and the photodetector in a state most suitable for measuring. The system monitors the quantity of light antecedent to irradiating a sample and quantity of light on a photodetector after irradiating a sample, and adjusts the position of a light source, the photodetector, or an optical device positioned between the light source and the photodetector.
In yet another embodiment, the present invention discloses a light scattering particle size distribution measuring apparatus capable of holding the control data antecedent to the decrease of the quantity of light when the quantity of light on a photodetector is significantly lowered compared with the quantity of light antecedent to irradiating a sample by monitoring the quantity of light antecedent to irradiating a sample and the quantity of light on a photodetector. In addition, the present embodiment is capable of retrieving the optimal positions of various optical components in a range, thereby automatically controlling the quantity of light on a photodetector.
In the light scattering particle size distribution measuring apparatus having the constitution described above, an automatic adjustment mechanism aligns the central position of the photodetector with the central position of the light source. The optical axis adjustment, which, conventionally was required to be manually performed by the operator, or through a control software stored on the personal computer, before measuring the particle size, becomes unnecessary. It is, therefore, possible to reduce the time required for each measurement, such as preparatory work before measuring. In addition, the present system is capable of always measuring in optimal conditions, thereby consistently achieving a particle size distribution measurement having a high degree of measuring precision.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view showing a first embodiment of the present invention.
FIG. 2 is a view showing a second embodiment of the present invention.
FIG. 3 is a view showing a third embodiment of the present invention.
FIG. 4 is a view showing a fourth embodiment of the present invention.
FIG. 5 is a view showing a fifth embodiment of the present invention.
FIG. 6 is a view showing a sixth embodiment of the present invention.
FIG. 7 is a view to illustrate a prior art system.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a first embodiment of the present invention. As shown in FIG. 1, the particle size measuring system comprises a light source 1 capable of emitting laser light 2 . The quantity of light emitted from this light source 1 is controlled and monitored by a CPU 15 described herein. The laser light 2 is modulated by a light shutter 3 , which comprises a shutter member 4 and a shutter driving member 5 . Thereafter, a beam expander 6 expands laser light 2 emitted from the light source 1 . The laser light 2 continues through a flow-through cell 7 containing a material sample 8 , and is focused with a condenser lens 9 onto a photodetector 10 . In an alternate embodiment, the condenser lends 9 may be between the beam expander 6 and the cell 7 , thereby condensing the laser light 2 incident upon the sample 8 . The photodetector detects 10 comprises a light receiving device 11 having a plurality of arc-shaped receiving devices 12 located an appropriate distance from the center of the optical axis. The foregoing light receiving devices 11 and 12 comprise and may include a plurality of light receiving device known in the art, including, for example, photodiodes. The light receiving devices 11 and 12 may be positioned at a predetermined position on a base member 13 . A multiplexer 14 captures the signal from the photodetector 10 . The CPU 15 processes the signal from the multiplexer 14 and determines the particle size distribution by performing arithmetic computations on the basis of a scatter light intensity pattern. Thereafter, a personal computer 16 may be used for controlling arithmetic computations, controlling the measuring apparatus, and performing image processing functions. A display unit 17 , in communication with the personal computer 16 , may be used to display the computational results.
As shown in FIG. 1, a diffraction device 18 , capable of producing diffracted light, is inserted into the optical path of the propagating laser light 2 . The diffraction device 18 comprises a plate member 20 , having a central opening 21 formed therein. Those skilled in the art will appreciate the diffraction device 18 of the present invention may be inserted into the optical path manually, or if desired, independently with an appropriate mechanism. The plate member 20 of the present invention may be manufactured from a plurality of materials, including, for example, light extinction materials and light absorbing materials. In an alternate embodiment, a transparent plate member 20 having light absorption material centrally located thereon, thereby enabling the user to produce spherical particle diffraction.
FIG. 1 shows an adjusting mechanism 19 which comprises, for example, an X-Y stage capable of movement in two directions X and Y, orthogonal to each other. As shown, the photodetector 10 is positioned on the X-Y stage 19 . Directional actuators 22 and 23 may be used to drive the X-Y stage 19 in X direction (a direction indicated by an arrow 24 ) and Y direction (a direction indicated by an arrow 25 ), respectively. The directional actuators 22 and 23 may comprise direct-acting actuators such as a piezoelectric device or a stepping motor. As shown in FIG. 1, the directional actuators 22 and 23 are controlled by a signal from a personal computer 16 . In an alternate embodiment, a manually controlled adjustment mechanism 19 is contemplated.
Those skilled in the art will appreciate the present invention is greatly different from the prior art systems in that the diffraction device 18 , which is positionable within the propagation path of the laser light 2 , is capable of adjusting the optical axis in the optical path between the light source 1 and the photodetector 10 . In addition, further adjustments to the optical axis may be achieved with the adjusting mechanism 19 coupled to the photodetector 10 .
FIG. 2 shows a second embodiment of the present invention in which a mirror 26 in communication with an optical axis adjusting mechanism 27 is provided. The mirror 26 directs the laser light 2 emitted from the light source 1 at a 90 degree angle into the beam expander 6 . As shown, the optical axis adjusting mechanism 27 , which is controlled by the CPU 15 , is capable of moving the mirror 26 in the directions indicated by the arrows 28 and/or 29 .
FIG. 3 shows a third embodiment of the present invention in which an optical axis adjusting mechanism 30 , which is controllable by the CPU 15 , is provided. As shown in FIG. 3, the optical axis adjusting mechanism 30 is capable of moving the condenser lens 9 and the optical axis in X direction as indicated by the arrow 31 and/or in Y direction as indicated by the arrow 32 .
FIG. 4 shows a fourth embodiment of the present invention in which an optical axis adjusting mechanism 33 , which is in communication with the CPU 15 , is provided. The optical axis adjustment mechanism 33 is capable of moving the beam expander 6 in the X direction as indicated by the arrow 34 and/or in Y direction as indicated by the arrow 35 .
FIG. 5 shows a fifth embodiment of the present invention in which an optical axis adjusting mechanism 36 , which is controlled by the CPU 15 , is provided. The optical axis adjusting mechanism 36 is capable of moving the light source 1 in the X direction as indicated by an arrow 37 and/or in the Y direction as indicated by an arrow 38 .
FIG. 6 shows a sixth embodiment of the present invention in which cuneal prisms 39 and 40 are positioned between the beam expander 6 and the cell 7 within the propagation path of the laser light 2 . As shown in FIG. 6, the cuneal prisms 39 and 40 are connected to an optical axis adjusting mechanism 41 , which is in communication with the CPU 15 . The optical axis mechanism 41 is capable of moving the cuneal prism 39 in the X direction as indicated by an arrow 42 , capable of moving the cuneal prism 40 in the Y direction as indicated by an arrow 43 .
The present invention further discloses a method of using the present invention to determine particle size. In the embodiments described above, the central positions of the light source 1 and the photodetector 10 are automatically adjusted to be in a state most suitable for measuring particle size within a sample 8 . The embodiments described above provide various systems capable of monitoring quantity of light prior to irradiating a sample 8 and quantity of light transmitted through the sample 8 incident on a photodetector 10 . In addition, the various embodiments of the present invention permit the user to easily adjust the position of a light source 1 , a photodetector 10 , or an optical device positioned between the light source 1 and the photodetector 10 . In an alternate embodiment, the present invention may also be constructed such that the CPU 15 is capable of performing a control and monitor function for the system. In addition to monitoring the light intensities as various points in the system, the CPU 15 is capable of performing an error detection process. Exemplary errors include bubble contamination of a sample and system misalignment. In another embodiment, the measuring system disclosed herein may also be capable of determining an optimal control position to make a quantity of light fall in a controllable range on the photodetector 10 . Additionally, the present invention is capable of storing the positions of various components, thereby enabling the system to reconstruct a previous experiment.
The present invention eliminates the burdensome manual optical axis adjustment currently required for every measurement in current systems. Furthermore, the present system permits the operator to maintain the system configuration best suited for a particular measurement. Accordingly, the present system enables the operator to perform measurements in an optimal condition while achieving a high degree of measuring precision.
To practice the first embodiment of the present invention, a diffraction device 18 is inserted into an optical path with the shutter 3 opened thereby creating an optical axis by using diffracted light produced by the diffraction device 18 . Once the optical axis is created, the diffraction device 18 may be removed from the propagation path. The CPU 15 , which is continuously receiving information relating to the position of the optical axis from the photodetector 10 , controls the optical axis adjusting mechanism 19 based on the foregoing information, thereby ensuring the photodetector 10 is always in a condition best suited to measuring.
In the embodiment described above, the optical axis adjusting mechanism 19 is in communication with the photodetector 10 and controlled by the CPU 15 . As shown in FIGS. 2 through 6, the present invention permits the user to control and monitor the optical axis with the CPU 15 by positioning the optical axis actuators in a plurality of locations. Accordingly, the operations for the optical axis adjustment in embodiments shown in FIGS. 2 to 6 are similar to that of the first embodiments shown in foregoing FIG. 1 .
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The present invention provides a light scattering particle size distribution measuring apparatus, which does not require a burdensome optical axis adjustment of operator for every measurement and which is capable of maintaining a state most suitable for measuring.
In the present invention, the light scattering particle size distribution measuring apparatus irradiates a sample with light from a light source, detects the resulting scattered light from the sample by a photodetector. Thereafter, the present invention calculates the size distribution of particles in the sample on the basis of the scattered light intensity pattern obtained. In addition, an automatic adjustment mechanism aligns and maintains the central position of the foregoing photodetector with the central position of the foregoing light source.
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BACKGROUND OF THE INVENTION
[0001] This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/880,959 filed Jan. 18, 2007, the entirety of which is incorporated by reference.
[0002] The present application is generally directed to making pulp and is more specifically directed to screen assemblies for pulp digesters.
[0003] Wood chips and other cellulosic fibrous material are treated in digesters to chemically separate fibers in the chips and material by, for example, removing lignins. A digester is a vessel in which wood chips are treated with heat, liquid, and chemicals to convert the chips to pulp. A continuous digester vessel is typically an upright cylinder with an upper inlet to receive chips in a continuous flow. The chips flow slowly through the digester vessel, 100 to 300 feet tall (30 to 100 meters) in a generally downward direction.
[0004] As the chips move through the continuous digester, the lignins binding fibers together in the chips release the fibers and the chips are converted to pulp. The pulp is removed through a bottom outlet of the digester. Chips are continually added to a continuous digester while the chips already in the digester vessel are processed and pulp is discharged from the bottom of the vessel. In a batch digester, chips are first loaded in a vessel, the loaded chips are processed as a batch and thereafter the processed chips are discharged to empty the vessel. In a batch digester the chips tend to remain in substantially the same location in the vessel.
[0005] Chemicals, e.g., cooking liquor, in a digester process the chips, cause lignins to unbind fibers and convert the chips to pulp. The chemicals are included in cooking liquor that is continuously pumped into and out of batch and continuous digesters. Screen plates are used in conventional digesters for the production of chemical cellulose pulp, e.g. kraft pulp, for both continuous and batch digesters. Screen plates are filters that allow liquor to be extracted from a digester but prevent the extraction of fibrous material. Screen plates are generally arranged around an inner circumference of a digester. An inner surface of the plate is exposed to the chip slurry in the digester and an outer surface of the plate forms a wall to a liquor extraction chamber. The screen plate may have multiple rows of narrow slots through which liquor (but not fiber) is extracted from the chip slurry and flows into the extraction chamber.
[0006] The slots in screen plates tend to clog or plug with fibers and have been a source of a decrease in pulp process quality. Various types of slot designs have been developed to reduce the tendency of clogging and plugging. For example, orienting the slots diagonally to the vertical axis and horizontal planes of the digester has been found to reduce clogging and plugging of slots. See U.S. Pat. No. 6,165,323. However, clogging and plugging of the diagonal slots still occurs and there continues to be a long felt need for devices that further reduce the tendency of slot clogging and plugging.
[0007] A concern has arisen that chips in a digester clog the slots of a digester screen. Slots are narrow to block chips from being withdrawn from a digester along with the cooking liquor. While narrow, there is a risk that chips become logged in slots. This risk is relatively large with vertical slots in a continuous digester where chips move in the same direction of the slots. This risk is decreased with diagonal slots in which chips move vertically and at an angle with respect to the slots. As chips move across the diagonal slots, the chips may catch on the slots and clog the slots.
[0008] There is a long felt need for slots, especially diagonal slots, in a screen plate that have reduced risk of being clogged or plugged by chips. The need arises from the difficulties that occur when chips clog slots and prevent the flow of cooking liquor through the screen and out of the digester. While the need is greatest with respect to continuous digesters, there is also a need for clog free slots in screen plates for batch digesters, especially for diagonal screen plates.
BRIEF DESCRIPTION OF THE INVENTION
[0009] A novel screen plate has been developed comprising slots having curved inlet edges to minimize chips begin caught on the edges and deflect chips into the pulp flow. The curved inlet slot edges are adjacent an inside surface of the screen plate and face the pulp flow. The curved inlet slot edges may be rounded, sloped or inclined. For example, inlets may have a generous radius of curvature equal to one third to two thirds the thickness of the plate. The curved inlets may be only on the lower side surface of a slot or on the upper and lower slot side surfaces. A curved inlet only on the lower side surface is suitable for a continuous digester in which the pulp flow is generally downward and chips tend to impinge on the inlet edge of the lower sides of slots. Curved inlets on both the upper and lower side surfaces of slots is suitable for both continuous and batch digesters. In addition, the lower side surface of the slot may be horizontal in cross-section or be inclined upward from the inside surface of the plate to the outer surface. Such a horizontal or upwardly inclined lower slot surface tends to deflect chips in the slot out of the slot and into the pulp stream.
[0010] A screen plate for a cellulosic material puling vessel, the screen plate including: slots having curved inlet corner edges adjacent an inside surface of the screen plate and facing a pulp flow.
[0011] A screen plate assembly has been developed for a continuous digester vessel for pulping cellulosic material, the assembly comprising: a plurality of screen plates for a cellulosic material puling vessel, each plate having a arc shape in cross-section, and said screen plates being assembled to form an annulus attached to an inside surface of the digester vessel, and each screen plate including slots having curved inlet corner edges adjacent an inside surface of the screen plate and facing a pulp flow.
[0012] A method has been developed for extracting a liquid from a continuous digester vessel, the method comprising: processing cellulosic material and a liquid in the vessel, wherein the cellulosic material flows through the vessel until the material is discharged from a discharge output of the vessel; extracting a portion of the liquid through a screen plate assembly, wherein the screen plates are assembled to form an annulus attached to an inside surface of the digester vessel, and each screen plate includes slots having curved inlet corner edges adjacent an inside surface of the screen plate and facing a pulp flow, and deflecting cellulosic material flowing through the vessel with the curved inlet corner edges to avoid the material become caught in the slots.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a front view of a conventional continuous digester shown schematically and partially cut away.
[0014] FIG. 2 is a front view of a conventional inner screening assembly and wall of the digester shown schematically.
[0015] FIG. 3 is a front view of several assembled screen plates in a conventional screening assembly.
[0016] FIGS. 4 and 5 are front and back views, respectively, of a portion of a conventional screen plate.
[0017] FIG. 6 is a partial cross-section of a conventional screen plate taken along line 6 - 6 in FIG. 5 .
[0018] FIG. 7 is a front view of a first embodiment of a screen plate having diagonal slots with curved, e.g., rounded, inlet edges.
[0019] FIG. 8 a cross-sectional side view of the first embodiment of a screen plate, where the view is taken along line 8 - 8 in FIG. 7 .
[0020] FIG. 9 is a front of a second embodiment of a screen plate having diagonal slots with rounded inlet edges.
[0021] FIG. 10 a cross-sectional side view of the first embodiment of a screen plate, where the view is taken along line 10 - 10 in FIG. 9 .
DETAILED DESCRIPTION OF THE INVENTION
[0022] FIG. 1 is a side view of a continuous vertical digester 10 for processing cellulosic fiber material, e.g., wood chips, into fiber pulp. Though a vertical continuous digester is shown, the screen plates and screen slots described herein are applicable to other types of cylindrical continuous and batch digesters. While the novel screen plates disclosed herein are shown in the context of a continuous digester, the screen plates are applicable to batch digesters.
[0023] A slurry of comminuted cellulosic fibrous material and cooking chemical is introduced at the top 12 of the digester and a slurry of fully-cooked pulp and spent cooking liquor is discharged at the bottom 14 . The digester 10 comprises a cylindrical shell 16 that typically forms a column of, for example, 100 feet (30 meters) tall. Within the cylindrical shell are several cylindrical screen assemblies 18 .
[0024] FIG. 2 is an inside view of a screen assembly 18 having an multiple elevations of cylindrical screen sections 20 . The screens may include screen plates 22 assembled to form the cylindrical screen section. The screen plates are attached to a frame 24 on the inner wall of shell 16 . The frame 24 , for example, comprises metal bars, angle irons, or like structural elements which are connected directly to the digester outer shell 16 , although the frame 24 may be distinct and detachable from the digester. Each screen section forms generally an annular ring around the inside wall of the cylindrical shell 16 of the digester 10 .
[0025] FIG. 3 is a schematic diagram of a portion of a screen section 20 in a screen assembly 18 . The section includes an array of metal screen plates 26 . Each plate has rows of trapezoidal screen slot regions 34 (shown schematically in FIG. 3 ). These slot regions define rows of screen slots, such as the slot rows 34 shown in FIGS. 4 and 5 . Between the slot regions 34 on a screen plate are land areas 38 that are parallel to the slot regions.
[0026] The slot regions 34 are shown as horizontal rows in FIG. 3 and as vertical columns in FIG. 2 . The orientation of the slot regions may vary from digester to digester; from screen assembly to assembly in a single digester; from screen section to screen section, and from slot region to slot region in a single screen section or screen plate. While the slot regions 34 are generally oriented vertically or horizontally, they may also be arranged on a diagonal with respect to the digester.
[0027] The screen plates have narrow slots or apertures (collectively referred to as slots) that extend through the thickness of the plate 26 and allow liquor, but not fibers, to pass through the plates. The slots may be arranged in various orientations such as vertically, horizontally, or at an oblique angle, such as at a 45-degree angle from the vertical. Diagonal slots have been found to be more resistant to becoming clogged/plugged with fibers, that are vertical and horizontal slots.
[0028] An annular chamber 28 for collecting the liquor is generally behind each screen assembly 18 . Liquor is withdrawn through each screen from the flow (F) of the pulp slurry moving generally downwardly through the digester. Beneath each annular chamber 28 are generally smaller annular cavities 30 , commonly referred to as “internal headers”, for collecting the liquor from the chambers 28 . Liquor collected in the cavities 30 is discharge through liquor removal conduits 32 . Though these chambers and cavities are shown as being located internal to the shell 16 , they may also be located external to the shell, that is, “external headers” may be used.
[0029] The screen assembly 18 is shown as having a continuous cylindrical screen surface formed of a screen plate 26 , where the plate has sections, e.g., rows, of screen slots. However, the screen surface may not be continuous or cylindrical. For example, the screen surface may also comprise multiple individual circular screens, or the screen surface may comprise alternating screen surfaces and blank plates, commonly referred to as a “checker board pattern”. More than one such screen assembly 18 can be used in the same digester vessel 10 . Further, the screen assembly may be tapered such that the diameter of the bottom of the screen assembly may be greater than the diameter at the top. Tapered screen assemblies may be used to span a region of increasing diameter in the digester vessel.
[0030] Each screen assembly 18 is shown as having a screen sections with multiple screen plates, for example three elevations, e.g., upper, middle and lower. The number of screen plates 26 in each section 20 and assembly 18 may vary from assembly to assembly in a single digester, and from digester to digester. The width of the slots in the screen plate can be, for example, in a range of 3 mm to 9 mm. Further, the slot shape, sizing and orientation in each section 20 screen plates may vary. For example, the width of slots in the upper section may be approximately 3 mm to 4 mm, which may be narrower than the width of the slots in the middle section, e.g. approximately 4-5 mm. Similarly, the width of slots in the middle section may be narrower than the width of slots in the lower section, e.g. approximately 5-6 mm. By using slots of increasing width at lower screen in a screen assembly 18 is believed to reduce the tendency of the slots to clog with fibers from the pulp slurry. Moreover, the length of the slots in a screen plate may be uniform, even from one section to another section.
[0031] As shown in FIG. 4 , the slots regions 34 shown in the screen plate 38 are diagonal and form an angle (α) with respect to horizontal. The orientation of the slots may vary from digester to digester; from screen assembly to assembly in a single digester; from screen section to screen section, and from row to row of slots in a single screen or screen plate.
[0032] Individual machined slots 40 generally form a horizontal row that comprise a slot region 34 . FIG. 4 shows an outer surface 42 of the screen plate 26 , where the outer surface faces the liquor chamber 30 . FIG. 5 shows an inner surface 44 of the screen plate 26 , where the inner surface faces the chip slurry in the digester vessel. The screen plates are secured to the frame 28 by pins 46 that extend through pin holes 48 in the plate. Several pin and pin holes may be used to secure each screen plate 26 to the frame 28 .
[0033] Each of the schematically illustrated slots 40 are diagonal and are oriented at an angle alpha α with respect to the vertical axis or a horizontal plane of the digester vessel. While slots may be aligned vertically or horizontally with respect to the pulp flow (F) direction, diagonal slots are less prone to clogging/plugging. The slot angle at ( FIG. 4 ) may be between 30 to 60 degrees, and is preferably about 45 degrees. The slot angle is the angle formed by the axis of the slot parallel to the plate with respect to a vertical axis of the vessel.
[0034] Each of the slots 40 is spaced from an adjacent slot by a horizontal distance 50 of about one inch, e.g., between 0.75-1.5 inches. Each of the slot regions 34 has a vertical dimension 52 of between 1.5 to three times the distance 50 between adjacent slots 40 .
[0035] The land areas 38 have a vertical dimension 54 , which preferably is approximately equal to the slot 40 vertical dimension 52 , e.g. about two inches. Preferably the slot vertical (or horizontal) dimension 52 for each of the slot region (row) 34 and the vertical (or horizontal) dimension 54 for the land areas 38 are substantially the same in any particular screen plate, although under some circumstances they may vary. Also, preferably the slot angle at is the same for all the slots 40 from one slot region 34 to the next in a screen plate, although again there may be variations from region to region. Also preferably all of the slot regions 34 within a given screen plate 26 have the same orientation, but from one screen plate 26 to the next, vertically, the slots 40 may have opposite orientations (that is for one screen plate the slots 40 may slant up left to right from top to bottom, and the other right to left from top to bottom).
[0036] As shown in FIG. 6 , the slots 40 in each slot region 34 have a narrow opening at the inner surface 44 of the plate 36 and a wide opening at the outer surface 42 of the plate. The width (W) of a slot may be taken the narrow dimension of the slot, as compared to the length (L) of the slot (as shown in FIG. 4 ). The thickness (T) of the slot is the thickness of the plate 36 . If the slot is tapered along its thickness (T), the angle of the taper may be beta (β) ( FIG. 6 ), e.g., 30 degrees. In a specific embodiment, the width (W) may be measured at the narrowest opening of the slot, such as at the outer surface 42 of the plate 36 . Generally, all slots 40 in a slot region 34 (and even in a screen plate) have uniform widths (W), lengths (L), thicknesses (T) and tapers (β). However, the slot width (W) may vary from slot region to region, from screen plate to plate, and/or from screen section to screen section within a screen assembly.
[0037] FIGS. 7 and 8 are a front and a cross-sectional side views, respectively, of a first embodiment of a screen plate 50 having diagonal slots with rounded inlet edges. The screen plate shown in FIGS. 7 and 8 are most suitable for continuous digesters in which the pulp slurry moves past the slots in a downward direction. The plate 50 may also be applied in a batch digester. The slots 52 are diagonal and arranged in rows of slot regions 54 . Chips 56 in a pulp slurry flow in a direction (F) generally downward in a continuous digester and may be generally stationary in a batch digester. An inside surface 58 of the plate faces the flow (F) of chip and an outside surface 60 faces the liquor collection chambers. The width (X) of the slots at their throat is the narrowest section of the slot. The width (X) may be, for example, 2 to 9 millimeters.
[0038] A lower side 62 of each slot extends the length of the slot and is on the downstream side of the slot with respect to the flow (F) direction. The lower side has a curved inlet 64 which may be, for example, rounded, angled, sloped, chamfered, beveled and slanted. The curved inlet 64 is less susceptible to catching chips 56 in the pulp flow (F). Sharp inlet edges, especially the edges of the lower side of slots, found on prior art slots are more likely to catch chips and thus allow chips to clog the slot. The curved inlet 64 on the slot shown in FIGS. 7 and 8 , and especially on the lower side of the slot, tends to deflect chips back into the flow (F) and away from the slot.
[0039] The curvature of the slot inlet may be defined by a radius of the curvature. The radius may be, for example, one-third to two-third of the thickness (T) of the plate. In view of the curved inlet, the narrowest region of the slot (X) may be inward of the inlet 64 . The narrowest region may be a throat just beyond the inlet and between the inner surface 58 and outer surface 60 of the plate.
[0040] The lower side surface 64 of each slot 52 may form an inclination angle (ω) of between zero to 15 degrees, and preferably 5 to 15 degrees, with respect to horizontal. This inclination angle causes the cross-section of the lower side surface to be parallel to horizontal or have an upward incline with respect to the inside surface 58 of the plate. The lower side surface with a horizontal or inclined slope tends to deflect chips that are drawn into the slot back into the pulp flow (F) and away from the slot. The slope of the lower side surface is inward on the plate of the curved inlet 64 . The combination of the curved inlet and horizontal or inclined lower side enhances the ability of the slots 52 to deflect chips into the pulp flow and avoid clogging.
[0041] The slots 52 in the plate 50 have an expanding opening with an opening angle (β) that facilitates the movement of liquor (FL) through the slot and the screen plate. In view of the slope of the lower side surface 62 , the opening angle (as indicated by the angle of arrow FL) is offset at an upward incline equal to the sum of one half the opening angle (β) and the inclination angle (ω) of the lower side of the slot. The offset upward opening angle results in the liquor flowing (FL) through the slot at a greater upward angle that with a conventional slot. In addition, the upper side 66 of each slot has an angle selected to provide the desired opening angle opening angle (β). For example, an angle of 45 degrees of the cross-section of the upper side 66 and a angle (ω) of 15 degrees for the lower side 62 provides an opening angle opening angle (β) of 30 degrees and an offset angle of 30 degrees, where the offset angle is illustrated by the average flow (FL) direction through the slot.
[0042] FIGS. 9 and 10 are a front and a cross-sectional side views, respectively of a second embodiment of a screen plate 70 having diagonal slots 72 and rounded inlet edges 74 . The plate 70 is more suitable for a batch digester in which the pulp slurry is relatively stationary with respect to the plates, but may be applied in a continuous digester. The plate 70 has a curved inlet edge 74 similar to the curved inlet edge 64 shown in FIG. 8 . The plate 70 has curved inlets 74 on the upper side wall 76 and lower side wall 78 of the slot, in contrast to a curved inlet edge only on the lower slot sidewall in the plate shown in FIG. 8 . The curved inlets 74 on the upper and lower slot sidewalls 78 may be, for example, rounded, angled, sloped, chamfered, beveled, and slanted. The curvature of the slot inlets 74 may be defined by a radius of the curvature. The radius may be, for example, one-third to two-third of the thickness (T) of the plate. In view of the curved inlet, the narrowest region of the slot (X) may be inward of the slot inlet. The narrowest region may be a throat just beyond the inlet and between the inner surface 58 and outer surface 60 of the plate.
[0043] The upper and lower slot sidewalls may each be slanted to form an expanding opening angle (β) of thirty degrees. The opening angle for the slots shown in FIGS. 7 to 10 may vary and preferably is in a range of 10 to 30 degrees. The opening angle for slot 72 is not offset is the angle for the slot 52 in FIG. 8 . The opening angle for slot 72 is symmetrical about a horizontal line.
[0044] While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
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A screen plate for a cellulosic material puling vessel, the screen plate including: slots having curved inlet corner edges adjacent an inside surface of the screen plate and facing a pulp flow.
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FIELD OF THE INVENTION
[0001] This invention relates to mass flow meters, particularly regarding their manufacture at decreased cost, yet of such quality for critical applications.
BACKGROUND OF THE INVENTION
[0002] The mass flow rate of a fluid (defined by its average velocity multiplied by its mass density multiplied by the cross-sectional area of the channel through which the flow travels) is a measured quantity of interest in the control or monitoring of most practical and industrial applications, such as any chemical reaction, combustion, heating, cooling, drying, mixing, fluid power, etc. Generally speaking, a thermal anemometer is used to measure the mass velocity at a point or small area in a flowing fluid—be it liquid or gas. The mass velocity of a flowing fluid is its velocity referenced to standard or normal temperature and pressure. The mass velocity averaged over the flow channel's cross-sectional area multiplied by the cross-sectional area is the standard or normal volumetric flow rate through the channel and is a common way of expressing the total mass flow rate through the channel.
[0003] The thermal anemometer is sometimes referred to as an immersible thermal mass flow meter because it is immersed in a flow stream or channel in contrast to other thermal mass flow meter systems, such as those which sense the total mass flow rate by means of a heated capillary tube mounted externally to the flow channel.
[0004] The operational principles of thermal anemometers derive from the fact that a heated sensor placed in a fluid stream transfers heat to the fluid in proportion to the mass flow rate of the fluid. In a thermal anemometer, one such heated sensor (commonly referred to as the velocity sensor) is provided together with another sensor that detects fluid temperature. In the constant-temperature mode of operation, the heated sensor is maintained at a constant temperature above the fluid temperature. The temperature difference between the flowing fluid and the heated sensor results in an electrical power demand in maintaining this constant temperature difference that increases proportional to the fluid mass flow rate and that can be calculated.
[0005] Alternately, some thermal anemometers operate in a constant-current mode wherein a constant current or power is applied to the heated sensor and the fluid mass flow rate is calculated from the difference in the temperature of the heated sensor and the fluid temperature sensor, which decreases as mass flow rate increases. Thermal anemometers have greater application to gases, rather than liquids, because their sensitivity in gases is higher than in liquids.
[0006] Because the parts of the heated sensor of known thermal anemometers are not sufficiently reproducible dimensionally or electrically, known thermal anemometers require multi-point flow calibration of electrical output versus mass flow rate, usually in the actual fluid and with the actual ranges of fluid temperature and pressure of the application. For industrial applications, the heated sensor and fluid temperature sensor of known thermal anemometers typically have their respective sensors encased in a protective housing shell (e.g., thermowell or metallic tube sealed at its end, etc.). Usually, the encased heated sensor is inserted into the tip of the housing and is surrounded by a potting compound, such as epoxy, ceramic cement, thermal grease, or alumina powder.
[0007] In such a system, “skin resistance” and stem conduction are two major contributors to non-ideal behavior and measurement errors in thermal anemometers constructed in this manner. Skin resistance is the thermal resistance between the encased heated sensor and the external surface of the housing exposed to the fluid flow. The well-known hot-wire thermal anemometers have zero skin resistance, but thermal anemometers with a housing do have skin resistance. The use of a potting compound substantially increases the skin resistance because such potting compounds have a relatively low thermal conductivity.
[0008] Skin resistance (in units of degrees Kelvin per watt) results in a temperature drop between the encased heated sensor and the external surface of the housing which increases as the electrical power supplied to the heated sensor increases. Skin resistance creates a “droop” and decreased sensitivity in the power versus fluid mass flow rate calibration curve, especially at higher mass flow rates. The droop is difficult to quantify and usually varies from meter to meter because of variations both in the parts of construction and in installation. The ultimate result of these skin-resistance problems is reduced accuracy. Furthermore, the use of a surrounding potting compound can create long-term measurement errors caused by aging and by cracking due to differential thermal expansion between the parts of the heated sensor. Accordingly, the highest quality heated sensors have a skin resistance with a low numerical value that remains constant over the long term.
[0009] Stem conduction (in units of watts) causes a fraction of the electrical power supplied to the encased heated sensor to be passed through the stem of the heated sensor, down the housing, lead wires, and other internal parts of the heated sensor, and ultimately to the exterior of the fluid flow channel. Stem conduction couples the electrical power supplied to the encased heated sensor to the ambient temperature outside the channel. If the ambient temperature decreases, stem conduction increases; if it increases, the conduction decreases. In either case, as ambient temperature changes, stem conduction changes, and measurement errors occur. Similarly, stem conduction is responsible for errors in the encased fluid temperature sensor's measurement because it too is coupled to the ambient temperature.
[0010] Further discussion of the operational principles of known immersible thermal mass flow meters, their several configurations, particular advantages, uses, skin resistance, and stem conduction are presented in section 29.2 entitled “Thermal Anemometry” by the lead inventor hereof as presented in The Measurement Instrumentation and Sensors Handbook, as well as U.S. Pat. Nos. 5,880,365; 5,879,082; and 5,780,736, all assigned to Sierra Instruments, Inc., and each incorporated by reference herein in its entirety.
[0011] As noted in the referenced material, resistance temperature detectors (RTDs) may be employed in the heated sensor and the fluid temperature sensor, when one is provided. Alternative sensors for either the heated sensor or the fluid temperature sensor include thermocouples, thermopiles, thermistors, micro-machined sensors and semiconductor junction thermometers. RTD sensors are generally recognized as being more accurate and stable than any of these alternatives.
[0012] RTD sensors operate on the principle of electrical resistance increasing in accordance with increasing temperature. Wire-wound sensors, thin-film sensors and micro-machined RTD sensors have been used variously in thermal anemometers.
[0013] Thin-film RTD (TFRTD) sensors offer an edge in accuracy because they are mass produced using automated production operations, employing technologies such as photolithography and lasers. This results in the comparatively high reproducibility, accuracy, stability, and cost-effectiveness of thin-film RTD sensors. Yet, prior to the teaching offered in U.S. Pat. Nos. 6,971,274 and 7,197,953, each to the lead inventor hereof, no high quality application of the thin-film RTD technology-based thermal anemometer was available for industrial applications.
[0014] Some thermal anemometers were available that used thin-film RTDs not entirely encased in a protective housing, with the RTD surfaces directly exposed to the fluid. However, due to the fragility, poorer dimensional tolerances, and the oscillating and turbulent flow around the thin-film RTD body, etc., such devices—standing alone—had only proven suitable for light duty, low-end, low-accuracy/precision requirement applications. Still, there are examples in which a thin-film RTD sensor was encased in the tip of a metallic tube (e.g., 316 stainless steel) sealed at its end and surrounded by a potting compound (e.g., epoxy, ceramic cement, thermal grease, or alumina powder). Yet, sensor fabrication with such potting compounds is inherently irreproducible due to variations in their composition, amount used, insufficient wetting of surfaces, and/or air bubbles. These irreproducibilities, combined with the aforementioned high skin resistance and potential for long-term instability associated with the use of potting compounds, limits the overall accuracy of known thermal anemometers constructed in this manner.
[0015] The above-referenced Olin patents offered solutions to provide robust and highly accurate thermal anemometers using thin-film RTD technology. Specifically, in a “dry” heated sensor, an apparatus for use as a mass flow meter in a fluid is provided comprising a metal spacer within a metal shell, the spacer having a cross section defining a circular diameter and a rectangular hole, with the spacer adapted to closely hold a thin-film RTD temperature sensor in the hole and with the spacer closely held in a outer casing or shell. In this assembly, the metal spacer body comprises a powdered metal fabricated piece or a machined metal solid. Thus, the active portion of the heated sensor has no potting compound or other bonding materials adjacent thereto.
[0016] While of superb quality, such devices have proven less cost-effective to manufacture that those of the present invention. While, at the same time, those according to the present invention offer the same—and possibly better—performance. As such, the present invention offers a further advance in the art.
SUMMARY OF THE INVENTION
[0017] The present invention offers a mode of device construction in connection with thin-film RTD sensors that is able to leverage the cost advantage offered by such products, but still attain the measurement quality required of scientific and industrial applications. Namely, systems according to the present invention offer performance with as low as about 1% to about 2% of reading error in accuracy over a mass flow rate range of about 10% to about 100% of full scale (or larger), and over a relatively larger fluid temperature and pressure range. When coupled with computations based on heat-transfer correlations and other corrective algorithms, devices constructed according to the present invention optionally allow fewer flow calibration points, calibration with a low-cost surrogate flow calibration fluid (i.e., air in lieu of other gases), and grade “A” to “A+” accuracy over wider ranges for mass flow rate, fluid temperature, and fluid pressure.
[0018] To achieve one or more of these benefits, the present invention utilizes a shell-and-spacer architecture. But instead of seeking to capture the thin-film RTD closely in the spacer and the spacer within a shell (as in the above-reference '274 Olin family patents), the spacer is configured to provide both internal and external gaps, where the internal gap is between itself and the sensor(s), and an external gap is between itself and a housing shell. Together with an open bore, the open spacing enables securing the spacer containing at least one thin-film RTD in a housing shell by immersing the spacer and RTD(s) in a bolus of fill material. Advantageously, the fill material is braze or solder that liquefies solidifies after heating to allow the immersion.
[0019] With the spacer and RTD(s) so-encased, high thermal resistance air gaps are eliminated (or at least substantially eliminated) as a combination of displacement and/or capillary action push/draw the liquid solder/braze into the engineered gaps and chase out the air. The liquid then cools so it solidifies. The thermal conductivity of the solidified solder/braze and small size of the gaps (detailed further below) provides for very good overall thermal conductance of the portion of the meter in which the spacer and RTD(s) is/are housed, resulting in the desired low level of skin resistance.
[0020] The use of solder or braze as fill material offers another advantage. With the glass-coated thin-firm RTD(s) bonded into the spacer and the spacer bonded into the shell, a highly dimensionally stable and vibration-resistant construction results. To ensure dimensional stability, it is desirable to use shell and spacer metals with matched (or at least approximately matched) thermal expansion ratios as in the case of stainless steel and copper. As for the solder or braze, there is very little of it to expand/contract and create high internal stresses. Rather, its ductility favors riding along with any expansion and contraction of the major sensor body elements (i.e., the shell and spacer, and the spacer and the sensor).
[0021] Regarding vibration resistance, the solder or braze helps stabilize or “hold-in” the thin platinum film lattice, thereby protecting it from vibration problems. According to the article “Trends in Process Temperature Measurement: An Evolving Technology Segment Changes Focus to Meet End - User Needs, ” by Mike Cushing published in the Industry Outlook Section of the November 2007 issue of Flow Control, thin-film RTDs do not perform as well as wire-wound RTD elements in high-vibration and severe mechanical shock environments. However, when utilized with shell-and-spacer solder encasing as taught herein, thin-film RTDs can be effectively employed even in the most extreme conditions.
[0022] Another aspect of the invention that may assist in protecting against vibration damage involves the manner in which a pair of thin-film RTDs can be situated back-to-back within the spacer. Then, the lead wires thereto can be wound together starting where they emerge from the sensor body. This construct provides a stiffer, stronger configuration helping to avoid wire lead fracture/breakage due to vibration and shock loading.
[0023] In spite of the advantages, it is to be appreciated that the present invention can be practiced without the use of solder (or, alternatively, braze) as a gap filler. Rather, an altogether different fill material may be used. Such fillers include cements, thermal grease, epoxies and metal particle filled versions thereof. All of these, however, are less preferred than solder and/or higher temperature braze. These (and possibly other) flowable metals offer higher thermal conductivity, excellent ductility and are capable of forming a strong bond between elements that will not crack, thereby improving long-term stability.
[0024] As for configuring the spacer to provide a fillable gap between the shell and itself, such an approach allows for lower spacer element part cost (as compared to the previous “dry” sensor approach described above) by reducing part tolerance requirements, since no press-fit between the shell and spacer is required in order to achieve superb thermal conductivity and overall stability. Also, since it is the intent to fill the open space within the shell (possibly up to the level of the spacer), the far/distal end of the spacer need not be shaped to exactly match the distal profile of the shell. Rather, the spacer can simply be terminated. It may have a flat end. However, to reduce solder volume (and fill more volume with—typically—more highly conductive spacer material) the spacer more preferably is chamfered at its distal end. Such an end is easily turned to shape, while offering an approximate match to a domed shell end. In addition, a chamfered end may be useful in avoiding the production of air pockets in the solder when the spacer is submerged in a bolus of solder/braze.
[0025] Moreover, it is to be appreciated that not all variations of the invention are practiced with an outer housing shell. Rather, an inexpensive variation of the invention may be provided having only the spacer, fill material and thin-film RTD(s) therein, but no housing shell. In this variation, the spacer may have an extension from its proximal end connected to the greater mass flow sensor housing. Such an extension may be a thin-walled tubular body, or another shape adapted to minimize stem conduction. The extension may comprise part of the spacer itself, or it may be a separate element (e.g., a thin-walled stainless steel tube) connected thereto. In the latter case, the connection may be provided by soldering, brazing, press or shrink fit, a threaded interface, etc.
[0026] In any case, it may be desirable to make the spacer from more than one piece of material. In one advantageous arrangement, the spacer comprises two pieces stacked axially. Constructed in this manner, the depth of machined slots within the pieces is minimized, thereby allowing faster machining feed rates without tool breakage. Note also, while thin-film RTDs are generically referenced above, use of this terminology is also intended to apply to the preferred use of Thin-Film Platinum Resistance Temperature Detectors (TFPRTDs).
[0027] The assemblies described above may be configured in connection with relevant hardware for use as an insertion or as an in-line type flow meter. Complete mass flow meters include primary fluid temperature and velocity sensor elements. When one or more sensors are encased within the spacer, it constitutes the heated tip of the velocity sensor element. If another sensor separated from the heated tip a defined distance from the spacer is optionally provided, it enables compensation for stem conduction as described in U.S. Pat. No. 6,971,274 and 7,197,953.
[0028] With two sensors set in the spacer for the velocity sensor, an array is provided that can offer a lower “equivalent” resistance so that lower supply voltages (e.g., at 24 VDC as is standard) can be used to deliver the power required to the overall heated sensor element. So-arranged, two standard mass-produced sensors with higher resistances can be connected electrically in parallel to halve the equivalent resistance of the pair. Thus, for example, two 100 ohm sensors yield a 50 ohm equivalent resistance. Two thin-film RTDs back-to-back with active areas directed outward provide an advantageous, “neat” configuration since it performs essentially as a constant temperature unit because the heated areas are outside the mass of the sensor pair and are essentially at the same temperature.
[0029] However configured, the meter's sensor elements are typically used in connection with a programmed general-purpose computer or dedicated electronic control hardware—either example of such hardware including a data processor. In the present invention, each RTD sensor in the velocity sensor element is preferably a TFRTD sensor. It is desirable, though not necessary, for all of the sensors to be TFRTD sensors.
[0030] In sum, the present invention includes systems comprising any of the features described herein. Methodology, especially in connection with manufacture, also forms part of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] The figures diagrammatically illustrate aspects of the invention. Variation of the invention from that shown in the figures is contemplated, for example, as contemplated in a broader sense in the Summary above. Fluid flow direction is indicated in many of the figures by arrows.
[0032] FIGS. 1A and 1B show front and side views, respectively, of a thin-film RTD (TFRTD/TFPRTD) sensor element;
[0033] FIG. 2 shows a partial side-sectional view of a complete thermal anemometer sensor assembly including velocity and temperature sensor elements as may be employed in connection with the present invention;
[0034] FIG. 3 shows a partial sectional view of a preferred fluid temperature sensor element;
[0035] FIG. 4 shows a partial side-sectional view of a sensor head of a thermal anemometer with an insertion-type configuration according to the assembly of FIG. 2 set therein;
[0036] FIGS. 5A and 5B show a partial side-sectional view and an end view, respectively, of an alternative insertion-type thermal anemometer as may be employed in connection with the present invention;
[0037] FIG. 6 shows an oblique sectional view of a spacer interface member for one or more of the heated temperature sensors shown in FIGS. 1A and 1B ;
[0038] FIG. 7 shows a partial rotated side-sectional view of a velocity sensor element in accordance with the present invention.
DETAILED DESCRIPTION
[0039] Turning now to FIGS. 1A and 1B , these show a view of the type of temperature sensor 2 employed in the present invention. The sensor shown is a “thin film” type sensor as described above. The particular sensor shown is a Thin-Film Platinum Resistance Temperature Detector (TFPRTD) as commonly available. An active area 12 of the device is provided, over which area the TFPRTD is self-heated by current during use. Sensor 2 includes lead wires 4 connected to weld pads leading to active region 12 and covered by a glass strain relief 10 . The body 8 of the sensor is made of high-purity alumina, preferably held to a thickness tolerance within about ±0.002 to 0.001 inches as commonly available. A thin layer of glass electrical insulation 14 is provided over the TFPRTD active area. Of course, the PRTD is only exemplary as other TFRTDs may be employed in the invention. For example, other thin-film RTDs optionally employed in the invention may utilize nickel or other metals for the devices' electrically resistive array.
[0040] Details as to how any such hardware (as well as altogether different types of sensors) may be employed in connection with the subject velocity sensor element are provided further below. As for the more global construction of a thermal mass flow meter in which the present invention may function, FIG. 2 illustrates a velocity sensor element/assembly 30 and a fluid temperature sensor element/assembly 56 provided in a greater sensor housing assembly 60 . The sensor element assemblies are set within sensor head 62 with their respective leads optionally potted in epoxy, cement (or the like) with insulated wires 64 arranged for connection to a processor 66 .
[0041] While such constructional details are within the level of those with skill in the art to handle without undue experimentation, FIG. 3 illustrates a particular fluid temperature sensor element 56 as advantageously employed in the present invention.
[0042] As illustrated, the assembly preferably includes two TFRTDS. The distal sensor 72 is the primary sensor for measuring the temperature of the flowing fluid. The proximal sensor 70 compensates for stem conduction as described in U.S. Pat. No. 5,879,082. In some applications, such as those involving certain liquids and certain gases at high velocity, stem-conduction errors are relatively small and in those applications proximal temperature sensor 70 is not needed.
[0043] For thermal anemometers of an insertion-type configuration, yet another advantageous innovation is shown in FIG. 4 . Here, an open-ended protective sensor head 80 is shown in partial cross section. The sectional view reveals the placement of the velocity and fluid temperature sensor elements in the sensor head. On either side of the sensor elements/assemblies, legs 82 defining an open channel and extending beyond the sensor elements are provided. The legs are of particular use when a technician is installing a completed meter into a pipe section or other location. The legs prevent inadvertent damage of the sensor elements during the installation procedure as well as offering protection from mishandling in the meantime. Use of a protective shield for the sensor elements of insertion thermal anemometers has precedence, but such shields normally are closed at their distal end. The shielding of sensor head 80 of the present invention is open at its end and thereby eliminates the flow disturbance created at the distal end of closed ended shields and consummates ultimately in better accuracy.
[0044] FIGS. 5A and 5B show a complete probe assembly of an insertion-type meter constructed with tubular stem 88 and the sensor head 80 of FIG. 2 . This meter is sealed and connected to the flow channel or stream by means of a compression fitting, flange or other like means. The constituent elements of the system are as described and designated by numerals above.
[0045] To facilitate proper installation orientation by an end-user a pointer indicating flow direction may be incorporated in the housing. Moreover, the present invention is suited for use in connection with various other flow meter configurations in addition to those shown the various figures. As for other manners in which the present invention may be implemented (i.e., housed or integrated in a flow system, in the configuration of an in-line flow meter, etc.), these are either known or readily appreciated by one with skill in the art; further examples of which are sold by Sierra Instruments, Inc., and shown in the above-referenced '274 patent from which much of the above detailed description derives.
[0046] In addition, it is to be understood that the thermal anemometer of the invention retains advantageous performance if operated with either digital or analog sensor-drive electronics, or with a combination of both, in either the constant-temperature or constant-current modes of operations, all as described in the above mentioned book chapter authored by the inventor hereof. Digital electronics may be preferred for reason of simplified computations based on heat-transfer correlations and corrective algorithms, that compensate for any changes (e.g., as referenced to flow calibration conditions) in the fluid itself, fluid temperature, fluid pressure, ambient temperature, and other variables and influence parameters, thereby yielding higher system accuracy. Said heat-transfer correlations and corrective algorithms are based on known empirical heat transfer correlations, specific experimental data for the thermal anemometer of the present invention, physics-based heat transfer theory, and other sources.
Velocity Sensor Configuration
[0047] As for the features unique to the present invention (vs. those described above that may be incorporated in the invention), they concern the implementation of RTD and/or spacer capture within a velocity sensor element 30 . FIGS. 6 and 7 show a spacer member 20 according to the present invention for receiving one or more RTDs therein.
[0048] Interface member or spacer 20 preferably comprises a metal such as copper. The material is selected for its high thermal conductivity. As such, other metals and alloys including free-machining copper alloys, other copper alloys, bronze, brass, zinc, aluminum, aluminum alloy, silver, gold, alloys thereof, stainless steel, etc., as well as high thermal conductivity ceramics. The material should have a range of thermal conductivity between about 15 and about 500 watts per meter per degree Kelvin. The material selected for the spacer may preferably be one that is easily machined. Still, the spacer may be fabricated by any of conventional machining, laser or electrical discharge machining, powdered metal molding, injection molding, casting, extruding, stamping, forging, or by any other method suitable for producing tolerances as described herein.
[0049] In the present invention, spacer 20 provides an intermediate solid body between one or more sensors 2 and the housing shell 32 of the velocity sensor element 30 . As seen in FIG. 7 , the chamfered distal end 24 , with terminal annulus 24 ′, of the spacer provides an approximate match to housing shell 32 distal end 34 .
[0050] Since a goal of the spacer is to provide controlled gaps between the spacer, shell and/or sensors (which spaces are filled in order to purge highly insulative air spaces), the shape of bore 22 will depend on the shape of the sensor(s). In this invention, the pocket 26 shown is a slot adapted to receive two sensors with faces 28 substantially parallel to the active areas 12 of the sensors when assembled.
[0051] With an oblong or rectangular slot milled in the proximal and distal pieces ( 20 ′ and 20 ″, respectively) defining the overall spacer body 20 , vacant space is left open along the sides of the sensors when installed. This space it to be filled with solder (or otherwise) in a final assembly like that in FIG. 7 where the fill is indicated by stippling 36 .
[0052] It is advantageous to limit the gaps between the spacer 20 and the housing shell 32 and between the spacer 20 and the active face or faces 12 of sensors 2 to the range, preferably, of about 0.001 to about 0.007 inches on each side of the bodies. The range may, however, be broader between about 0.001 to about 0.015 inches, and up to about 0.020 inches maximum. If these gaps are significantly larger, the accuracy of the meter due to increased skin resistance is degraded when using a solder compound with a thermal conductivity less than the preferred copper spacer. This is of most concern for the gaps between the spacer and the active face or faces of the sensor(s) because the heat flux is highest there.
[0053] Additionally, larger gaps may reduce the long-term stability and strength of the joints. Solder also fills the gaps between the edges of the sensor(s) and the spacer bore 22 . Here, gap limitations are of less concern because a minority of heat is conducted from the sensor(s) to the spacer through these paths. In the case of multiple sensors and/or multiple spacer pieces, some solder may flow into the contact interface between said parts, but the extent and thickness of such interfacial solder layers are of minor consequence.
[0054] Further, this invention optionally encompasses the use of sensor(s) other than thin-film RTDs including, but not limited to, thermisters, thermocouples, thermopiles, micro-machined sensors, wire-wound RTDs and semiconductor junction thermometers. With any of these other optional sensors, the bore of the spacer is configured to adapt to the sensors' geometry with gaps suitable for filling and, thus, reducing skin resistance. However configured, according to the present invention, such skin resistance in the velocity sensor unit will be below about 1.5 degrees Kelvin per watt, typically be below about 1 degree Kelvin per watt, and more or most advantageously below about 0.5 degrees Kelvin per watt.
[0055] In order to best fill the inside of spacer body 20 during submersion in a bolus of liquid solder, the distal end of the spacer is opened. Distal opening 22 ′ is advantageously a round drilled or milled hole. So-configured, a ledge or slot base 26 ′ is provided to serve as a stop or abutment feature to precisely position the end of the sensor(s) within the spacer. As shown, both spacer pieces 20 ′ and 20 ″ are captured, together with sensors 2 in shell 32 by solder that has climbed (e.g., by capillary action and/or displacement due to the weight of the sensor/spacer subassembly and any additional force applied thereto) along the inner and outer surfaces of the gross spacer body 20 (i.e., along pieces 20 ′ and 20 ″).
[0056] To account for stem conduction, another thin-film RTD sensor 40 may be provided with ferrule 50 . It may also be desired to provide longitudinal spacer collar 52 to carefully define the distance between ferrule 50 (for when it might be included with a sensor 40 ) and spacer 20 carrying sensor(s) 2 . Collar 52 may have a tubular or other configuration that provides the defined distance and has a relatively low heat conductance.
[0057] Sensor leads, optionally encased in electrically insulative housing(s) 42 , connect to sensor 40 proximally. Likewise sensor lead wires 4 (not shown in FIG. 7 ) may be set with electrically insulative housing(s) 38 / 38 ′ as described further below in reference to sensor assembly, or otherwise. The electrically insulative housings may be tubes or glands having a single bore or multiple bores and may be constructed of plastic (e.g., fluorocarbons, such as Teflon®) and, for higher temperature applications, of ceramic (e.g., mullite or alumina) or other higher temperature electrically insulative materials. The washer-like ferrule 50 optionally has one or more holes for the passage of the electrically insulated sensor lead wires 4 and is constructed preferably of copper, but also may be constructed of another material, typically, with high thermal conductivity.
Velocity Sensor Assembly/Manufacture
[0058] In an exemplary mode of assembly, two 100 ohm TFPRTD sensors are held back-to-back in an electronics vice with their active areas facing outward. After the lead wires are untangled, four short electrically insulative, fluorocarbon tubes are threaded over each wire such that they press flush against the strain relief of the two sensors. Next, adjacent sensor wires are twisted such that the two sensors are electrically hooked up in parallel. So-configured, the twisted pairs may be fed through two longer fluorocarbon tubes.
[0059] The sensors are removed from the vice and inserted into the bore in the spacer until they bottom out. Then, the longitudinal spacer collar is slipped over the top of the twisted pairs. In the exemplary mode of assembly, the collar is constructed of a thin walled stainless steel tube. Next, the lead wires in the two longer fluorocarbon tubes are fed through the hole(s) in the ferrule. Finally, to complete the subassembly, the ferrule is pushed longitudinally against the collar effecting tight contact between the collar and ferrule, the collar and spacer, spacer pieces, and the sensors and the bottom of the spacer pocket.
[0060] After the sensor housing shell is prepared (e.g., by pickling solution, rinsed and dried) the subassembly can be secured in the housing shell. In the exemplary mode of assembly, the sensor housing shell is a stainless steel or nickel alloy tube. The area of the shell over which a solder connection is desired may be further prepared by coating with flux. So-too may be the interior and exterior of the spacer. After weighing out a desired amount of solder, it too may be coated or covered with flux. Such coating is most easily accomplished by coating a length wrapped around a rod. However, solder pellets, etc., may be employed—as may be flux core solder material.
[0061] In the exemplary mode of production, the solder mass is next set into the closed bottom or distal end of the sensor housing shell, with the shell oriented vertically. The subassembly is then inserted until it bottoms-out against the solder.
[0062] With care to maintain any desired orientation of the sensors relative to housing location features, the two electrodes of a resistive soldering machine are clamped to opposite sides of the distal tip of the velocity sensor housing shell. The electric current from the soldering machine flows from one electrode to the other generating heat in the tip of the shell. The TFPRTDs can be used to monitor the temperature of the tip. The voltage of the soldering machine is ramped up to a predetermined temperature set point that is sufficiently high to melt and flow the solder but is sufficiently lower that the melting points and other upper temperature limits of the TFPRTDs and all other components in or near the tip of the shell.
[0063] At a selected set point, the weight of the subassembly (optionally augmented by additional force) causes the subassembly to sink into the molten solder, upon which the distal end of the spacer should contact the closed distal end of the housing shell. In so doing, the spacer and sensor(s) displace a volume of molten solder so it flows via displacement and/or capillary action upward into the gaps between the spacer and the housing shell and between the TFPRTDs and the spacer.
[0064] The weight of the charge of solder loaded into the tip of the shell is selected so that this process results in the solder level in all gaps just reaching the top, or proximal, end of the spacer. If the spacer is constructed of more than one piece and/or multiple sensors are employed, the contact interface(s) between such pieces may also fill with solder either totally or partially, either case being inconsequential to the invention herein.
[0065] In the optional case where an additional temperature sensor is used to correct for stem conduction, after the soldering machine is disconnected and the solder cools down and solidifies, the stem conduction temperature sensor with its electrically insulated leads is inserted down the housing shell until it bottoms-out on top of the ferrule. A suitable cement, epoxy, or similar compound may be employed above the ferrule to fix the sensor in place and provide thermal contact.
[0066] Naturally, other approaches may be employed to carry out the soldering procedure. For instance, the end of the shell may be heated directly by a soldering iron, radiant energy and/or convective flow.
[0067] Moreover, various parts can be “pre-tinned”. Other preparation is possible as well. Namely, for the sake of avoiding diffusion between solder components and adjacent part(s) and/or the formation of intermetallic compounds, either one or both of the spacer and housing shell may be plated with a metallic (e.g., Nickel) or other barrier film.
[0068] While solders (e.g., silver, gold or lead-based solders) having a melting temperature (i.e., liquidus) in the range of about 200° C. to about 350° C. are advantageously employed, solders with higher or lower temperature ranges may be employed. Likewise, higher temperature “brazing” compounds (e.g., silver braze) or other low melting point metals may be employed. In all cases, such “fill” materials have both the liquidus and solidus (i.e., the solidifying temperature point) sufficiently less than the melting point and other upper temperature limitations of the thin-film RTD and/or lead wire, electrically insulative material and, less typically, of the spacer, housing shell, and ferrule. When using TFPRTD(s) and ceramic lead-wire insulators, the solidus and liquidus of the solder/braze compound will typically be less than about 650° C. Finally, the solder/braze compound for a given application may also be selected for stability at its interfaces with the housing shell and spacer.
[0069] Regarding assembly of the remaining portions of a fully-functional mass flow sensor, the required techniques are well known in the art. Even so, reference is made to the above-referenced commonly assigned patents, incorporated herein by reference for such other description and/or detail.
Variations
[0070] Exemplary aspects of the invention, together with details regarding material selection and manufacture have been set forth above. As for other details of the present invention, these may be appreciated in connection with the above-referenced patents and publications as well as is generally known or appreciated by those with skill in the art. The same may hold true with respect to method-based aspects of the invention in terms of additional acts as commonly or logically employed. Regarding such methods, including methods of manufacture and use, these may be carried out in any order of the events which is logically possible, as well as any recited order of events. Furthermore, where a range of values is provided, it is understood that every intervening value, between the upper and lower limit of that range and any other stated or intervening value in the stated range is encompassed within the invention. Also, it is contemplated that any optional feature of the inventive variations described may be set forth and claimed independently, or in combination with any one or more of the features described herein.
[0071] Though the invention has been described in reference to several examples, optionally incorporating various features, the invention is not to be limited to that which is described or indicated as contemplated with respect to each variation of the invention. Various changes may be made to the invention described and equivalents (whether recited herein or not included for the sake of some brevity) may be substituted without departing from the true spirit and scope of the invention.
[0072] Reference to a singular item includes the possibility that there are a plurality of the same items present. More specifically, as used herein and in the appended claims, the singular forms “a,” “an,” “said,” and “the” include plural referents unless specifically stated otherwise. In other words, use of the articles allow for “at least one” of the subject item in the description above as well as the claims below. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation.
[0073] Without the use of such exclusive terminology, the term “comprising” in the claims shall allow for the inclusion of any additional element—irrespective of whether a given number of elements are enumerated in the claim, or the addition of a feature could be regarded as transforming the nature of an element set forth in the claims. Except as specifically defined herein, all technical and scientific terms used herein are to be given as broad a commonly understood meaning as possible while maintaining claim validity.
[0074] The breadth of the present invention is not to be limited to the examples provided and/or the subject specification, but rather only by the scope of the claim language.
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A thermal anemometer or mass flow meter typically having temperature and flow velocity sensor elements is provided in which a thin film temperature sensor is used in the heated sensor of the fluid velocity sensor element of the system. At least one thin-film RTD sensor is held within a spacer or interface member and the spacer, optionally, received within a housing. The thermal anemometer is preferably constructed to offer sufficient precision and accuracy in its design to be suitable for sensitive scientific and industrial applications. This goal is achieved while using cost effective parts by employing a construction approach in which the spacer and RTD sensor(s) is secured in place by solder, braze or another compound flowed into place while inserting the spacer and/or sensor(s).
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CROSS REFERENCES TO RELATED APPLICATIONS
[0001] This present application is a divisional application which claims the benefit of the filing date of U.S. patent application Ser. No. 10/871,799, filed Jun. 18, 2004, the disclosure of which is hereby incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] Electronic devices such as flat screen monitors or other electronic equipment are supported for use by a variety of known adjustable stands and/or extension arms. For example, there is known from U.S. Pat. No. 6,609,691 an adjustable extension arm for mounting a monitor to a supporting surface, the disclosure of which is incorporated herein by reference. The extension arm is constructed from a pair of nested channel members which form an adjustable parallelogram that permits the electronic device coupled thereto to be raised and lowered to a desired height. Such extension arms are useful when it is desired to elevate the monitor off a desk or other surface, in order that the device meets eye level or some other desired height. U.S. Pat. No. 6,499,704, the disclosure of which is incorporated herein by reference, discloses a pole stand having a base, a pole attached to the base, and a collar, which is positonable on the pole. The collar is provided with a support mount that can receive various coupling components, which may in turn be attached to an electronic device such as a monitor.
[0003] Despite these known adjustable stands and extension arms, there is the desire for further improvements in an adjustable support for an electronic device and mounting brackets for use therewith.
SUMMARY OF THE INVENTION
[0004] In accordance with an embodiment of the present invention, there is described a mounting apparatus for an electronic device, the mounting apparatus comprising an elongated beam having a longitudinal axis; and at least one bracket adapted to be coupled to an electronic device, the bracket including a body having a bore adapted to receive the beam therethrough, and a pair of spaced apart ribs extending from the body into said bore, the ribs adapted for engagement with the beam when the beam is received within the bore.
[0005] In accordance with a further embodiment of the present invention, there is described a mounting apparatus for an electronic device, the mounting apparatus comprising an elongated beam having a longitudinal axis, the beam having a bracket engagement portion; and at least one bracket adapted to be coupled to an electronic device, the bracket including an upper bracket member pivotably attached to a lower bracket member forming a bore therebetween, one of the upper and lower bracket members including a beam engagement portion accessible within the bore, the beam engagement portion coacting with the bracket engagement portion when the beam is received within the bore to prevent the bracket from twisting about the beam.
[0006] In accordance with a further embodiment of the present invention, there is described a mounting bracket adapted for coupling an electronic device to an elongated beam, the bracket comprising a body having a bore adapted to receive the beam therethrough, and a pair of spaced apart ribs extending from the aid body into the bore, the ribs adapted for engagement with the beam when the beam is received within the bore.
[0007] In accordance with a further embodiment of the present invention, there is described a mounting bracket adapted for coupling an electronic device to an elongated beam, the bracket comprising an upper bracket member pivotably attached to a lower bracket member forming a bore therebetween, one of the upper and lower bracket members including a beam engagement portion accessible within the bore, the beam engagement portion adapted for coacting with a portion of the beam when the beam is received within the bore to prevent the bracket from twisting about the beam.
[0008] In accordance with a further embodiment of the present invention, there is described a mounting bracket adapted for coupling an electronic device to an elongated beam, the bracket comprising a body having a bore adapted to receive the beam therethrough; means for preventing twisting of the body about the beam when the beam is received within the bore; and means for engaging a surface of the beam at spaced apart locations when the beam is received within the bore.
[0009] In accordance with a further embodiment of the present invention, there is described a mounting bracket adapted for coupling an electronic device to a curved elongated beam, the bracket comprising an upper bracket member pivotably attached to a lower bracket member between an open and closed position, the upper and lower bracket members forming a through bore therebetween when in the closed position, the bore having first and second spaced apart ends, first and second ribs extending from the upper and lower bracket members into the bore, the first rib arranged adjacent the first end and the second rib arranged adjacent the second end, each of the ribs having a curved inner surface adapted for engagement with a surface of the beam when received within the bore, and a beam engagement portion accessible within the bore adapted for coacting with a portion of the beam when received within the bore to prevent twisting of the bracket about the beam.
[0010] In accordance with a further embodiment of the present invention, there is described a mounting apparatus for an electronic device, the mounting apparatus comprising an elongated beam; and a mounting bracket adapted for coupling an electronic device to the elongated beam, the bracket comprising a body having a bore adapted to receive the beam therethrough, means for preventing twisting of the body about the beam when the beam is received within the bore, and means for engaging a surface of the beam at spaced apart locations when the beam is received within the bore.
[0011] In accordance with a further embodiment of the present invention, there is described a mounting apparatus for an electronic device, the apparatus comprising a curved elongated beam having a longitudinal axis, the beam having a bracket engagement portion extending along the axis; and at least one mounting bracket adapted for coupling an electronic device to the beam, the bracket comprising an upper bracket member pivotably attached to a lower bracket member between an open and closed position, the upper and lower bracket members forming a through bore therebetween when in the closed position, the bore having first and second spaced apart ends, first and second ribs extending from the upper and lower bracket members into the bore, the first rib arranged adjacent the first end and the second rib arranged adjacent the second end, each of the ribs having a curved inner surface adapted for engagement with a surface of the beam when received within the bore, and a beam engagement portion accessible within the bore adapted for coacting with the bracket engagement portion of the beam when received within the bore to prevent twisting of the bracket about the beam.
[0012] In accordance with a further embodiment of the present invention, there is described a mounting apparatus for adjusting the elevation of an electronic device coupled thereto, the mounting apparatus comprising an elongated beam having a longitudinal axis; and at least one bracket adapted to be coupled to an electronic device, the bracket including a body having a bore adapted to receive the beam therethrough, and means for adjusting the elevation of an electronic device when coupled thereto relative to the body.
[0013] In accordance with a further embodiment of the present invention, there is described a mounting apparatus for adjusting the elevation of an electronic device coupled thereto, the mounting apparatus comprising an elongated beam having a longitudinal axis; and at least one bracket adapted to be coupled to an electronic device, the bracket including a body having a threaded opening and a bore adapted to receive the beam therethrough, and an externally threaded bushing having an opening at one end thereof, the bushing threadingly received within the threaded opening within the body; and a coupling device received within the opening of the bushing for coupling an electronic device to the bracket, whereby the elevation of the electronic device can be adjusted by advancing the bushing through the body by rotation of the bushing.
[0014] In accordance with a further embodiment of the present invention, there is described a mounting bracket for adjusting the elevation of an electronic device coupled thereto, the bracket comprising a body adapted for coupling an electronic device thereto, and means for adjusting the elevation of an electronic device when coupled thereto relative to the body.
[0015] In accordance with a further embodiment of the present invention, there is described a mounting bracket for adjusting the elevation of an electronic device coupled thereto, the bracket comprising a body having a threaded opening, and an externally threaded bushing having an opening at one end thereof, the bushing threadingly received within said threaded opening within the body; and a coupling device received within the opening of the bushing for coupling an electronic device to the body, whereby the elevation of the electronic device can be adjusted by advancing the bushing through the body by rotation of the bushing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with features, objects, and advantages thereof may best be understood by reference to the following detailed description when read with the accompanying drawings in which:
[0017] FIG. 1 is a front elevational view of a mounting apparatus constructed in accordance with one embodiment of the present invention;
[0018] FIG. 2 is a perspective view of an elongated beam adapted for use in the mounting apparatus in accordance with one embodiment of the present invention;
[0019] FIG. 3 is a perspective view of a mounting bracket constructed in accordance with one embodiment of the present invention;
[0020] FIG. 4 is a perspective view, looking from above, of the upper bracket member of the mounting bracket shown in FIG. 3 ;
[0021] FIG. 5 is a perspective view, looking from below, of the upper bracket member of the mounting bracket shown in FIG. 3 ;
[0022] FIG. 6 is a front elevational view of the lower bracket member of the mounting bracket shown in FIG. 3 ;
[0023] FIG. 7 is a top plan view illustrating a plurality of electronic devices mounted to a curved elongated beam using a mounting bracket constructed in accordance with one embodiment of the present invention;
[0024] FIG. 8 is a diagrammatical illustration showing the relationship of a mounting bracket coupled to a curved elongated beam in accordance with one embodiment of the present invention;
[0025] FIG. 9 is a front elevational view of a mounting bracket constructed in accordance with another embodiment of the present invention;
[0026] FIG. 10 is a perspective view of a mounting bracket constructed in accordance with another embodiment of the present invention;
[0027] FIG. 11 is a perspective view of the projection shown in the mounting bracket shown in FIG. 10 ;
[0028] FIG. 12 is a front elevational view of a mounting bracket constructed in accordance with another embodiment of the present invention; and
[0029] FIG. 13 is a perspective view of a mounting bracket constructed in accordance with another embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] In describing the preferred embodiments of the invention illustrated in the drawings, specific terminology will be used for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents that operate in a similar manner to accomplish a similar purpose.
[0031] Referring now to the drawings, wherein like reference numerals represent like elements, there is shown in FIG. 1 a mounting apparatus generally designated by reference numeral 100 . The mounting apparatus 100 includes an elongated beam 102 and at least one mounting bracket for use therewith. In the embodiment shown in FIG. 1 , the mounting apparatus 100 includes a plurality of mounting brackets 104 , 106 , 108 , whose construction will be described hereinafter. An electronic device such as a flat screen monitor 110 is coupled to each of the mounting brackets by means of, for example, a tilter device 112 such as known from U.S. Pat. No. 6,505,988, the disclosure of which is incorporated herein by reference. The beam 102 is supported in a horizontal orientation overlying floor 114 by means of a stand 116 . As to be described hereinafter, the beam 102 may be also be supported from the ceiling, vertical wall or office furniture as may be desired.
[0032] Referring to FIG. 2 , there is illustrated one embodiment of a beam 102 adapted for supporting an electronic device via a mounting bracket. The beam 102 is constructed as an elongated member having a circular cross-section and a predetermined radius of curvature. The beam 102 , as shown, is constructed as a solid beam from a lightweight metal such as aluminum and the like. It is contemplated that the beam 102 may be constructed from other materials such as plastics and reinforced plastics, as well as a hollow tubular member or a hollow tubular member that is filled with a secondary material such as a metal or plastic filler.
[0033] In the preferred embodiment, the beam 102 has a circular cross-sectional shape. This facilitates bending of the beam 102 to the desired radius of curvature. However, it is contemplated that the beam 102 may have other geometric shapes, for example, polygonal, square, oval and the like. Although the beam 102 has a predetermined radius of curvature in accordance with the preferred embodiment, it is to be understood that the beam may also be linear without a radius of curvature if so desired.
[0034] The beam 102 is provided with a bracket engagement portion in the nature of an elongated slot 118 . The cross-sectional shape of the slot 118 may have various forms, for example, rectangular, keyhole, polygonal and the like. The slot 118 is provided extending along the longitudinal axis 119 of the beam generally arranged at its mid-point, for example, in alignment with the diameter of the beam 102 . As shown, the slot 118 is formed on the side of the beam 102 having the larger radius of curvature, i.e., outwardly of the beam. However, it is contemplated that the slot 11 8 may also be provided on the surface of the beam having the smaller radius of curvature, i.e., facing inwardly. Although the slot 118 has been shown as a continuous slot form one end of the beam 102 to the other, it is contemplated that the slot may be formed as segments which are discontinuous.
[0035] Referring now to FIGS. 3 through 6 , there will be described a mounting bracket constructed in accordance with one embodiment of the present invention. The mounting brackets 106 , 108 are adapted to be slid along the beam 102 for securing at a predetermined location. On the other hand, the mounting bracket 104 is intended to have a fixed location along the beam 102 . The construction of the mounting bracket 104 will be described hereinafter. As best shown in FIG. 3 , the mounting brackets 106 , 108 are constructed from a body 120 which includes an upper bracket member 122 and a lower bracket member 124 , and optionally, a bushing 126 .
[0036] The upper bracket member 122 includes a boss 128 having an upper surface 130 and a lower surface 132 . A threaded opening 134 extends through the boss 128 between the upper and lower surfaces 130 , 132 . A pair of spaced apart ribs 136 having an aligned through bore 138 are provided extending away from the lower surface 132 adjacent one end of the boss 128 .
[0037] An arcuate shaped member 140 extends away from the boss 128 having an inner curved surface 142 . The curved surface 142 is formed by a radius generally corresponding to the radius of the cylindrical beam 102 . In this regard, the shape of the inner surface 142 conforms to the shape of the beam 102 . In an embodiment where the beam 102 is polygonal in cross-sectional shape, the inner surface 142 of the upper bracket 142 will have a corresponding polygonal shape.
[0038] A projection 146 extends inwardly from the forward edge 148 of the arcuate shaped member 140 . The projection 146 is an elongated body having a cross-sectional shape generally conforming to the cross-sectional shape of the slot 118 formed in beam 102 . In this regard, the projection 146 is adapted to extend into the slot 118 , whereby the mounting bracket may slide longitudinally along the beam 102 while the projection is engaged within the slot. Thus, it is not a requirement that the projection 146 have the same corresponding shape as the slot 118 . Although the projection 146 has been shown as a single elongated body, it is contemplated that the projection may be formed from spaced apart segments, or a single projection whose length is shorter than the length of the arcuate shaped member 140 . The projection 146 extends inwardly into the opening formed by the inner curved surface 142 of the arcuate shaped member 140 .
[0039] The arcuate shaped member 140 includes a boss 150 formed outwardly thereof proximate the forward edge 148 . The boss 150 includes an opening 152 which may be threaded or non-threaded. As will be described hereinafter, the boss 150 is part of a locking assembly operative for securing the upper and lower bracket members 122 , 124 in assembled relationship about the beam 102 .
[0040] As thus far described, the arcuate shaped member 140 has an inner curved surface 142 which is generally planar between its spaced apart edges 154 , 156 . An elongated curved rib 158 extends projecting inwardly from the inner curved surface 142 of the arcuate shaped member 140 adjacent each edge 154 , 156 . The ribs 158 generally have a radius of curvature center corresponding to the radius of curvature center of the inner curved surface 142 of the arcuate shaped member 140 . As such, the outer edge of the ribs 158 generally lie in a circular plane parallel to the circular plane concentric with the inner curved surface 142 . Although the ribs 158 have been illustrated as continuous ribs substantially co-extensive with the edges 154 , 156 of the inner curved surface 142 , it is contemplated that the ribs may be formed as spaced apart segments. Although the ribs generally have a rectangular cross-sectional shape, they may have other shapes such as polygonal, triangular, trapezoidal or the like.
[0041] The lower bracket member 124 will now be described with reference to FIG. 6 . The lower bracket member 124 includes an arcuate shaped member 160 having an inner curved surface 162 . The inner curved surface 162 is defined by a radius of curvature generally corresponding to the radius of curvature of the inner curved surface 142 of the arcuate shaped member 140 . The inner curved surface 162 is generally of similar shape to inner curved surface 142 so as to conform with the cross-sectional shape of the beam 102 . In this regard, the upper and lower bracket members 122 , 124 when in their assembled closed relationship as shown in FIG. 3 define a through bore 164 having the general cross-sectional shape as the beam 102 . In the preferred embodiment, the bore 164 has a circular shape, although other shapes are contemplated as previously described, and wherein the longitudinal axis of the bore is arranged transverse to the longitudinal axis of the threaded opening 134 in boss 128 .
[0042] A rib 166 is formed extending outwardly from a central portion of one end 168 of the lower bracket member 124 . The rib 166 is adapted to be rotationally received within the opening 170 formed between the spaced apart ribs 136 on the upper bracket member 122 as best shown in FIG. 5 . Rib 166 includes a through bore 172 which aligns with bore 138 within ribs 136 so as to receive an axle 174 for pivotably attaching the upper and lower bracket members 122 , 124 together.
[0043] A boss 176 is provided extending outwardly from the other end 178 of the arcuate shaped member 160 . The boss 176 has a through opening 180 which may be threaded or unthreaded. In assembled relationship, the openings 152 , 180 are aligned with each other so as to accommodate a bolt, screw or other attachment means for securing the upper and lower bracket members 122 , 124 together in fixed assembled relationship. It is to be understood that other locking assemblies may be used such as clamps, hooks or other fasteners, both threaded and non-threaded, for securing the upper and lower bracket members 122 , 124 together.
[0044] An elongated curved rib 182 similar in construction to rib 158 is provided projecting inwardly from the inner curved surface 162 of the arcuate shaped member 160 adjacent its side edges 184 , 186 . The ribs 158 , 182 of the corresponding upper and lower bracket members 122 , 124 cooperate with each other to define the radial limits of the bore 164 formed thereby.
[0045] The projection 146 has been described as being formed extending inwardly from the upper bracket member 122 . It is to be understood that the projection 146 may be formed, in the alternative, extending inwardly from the lower bracket member 124 . It is further contemplated that a secondary projection 146 may be formed extending from the lower bracket member 124 to cooperate with the projection of the upper bracket member 124 so as to both be received within the slot 118 of the beam 102 .
[0046] The mounting brackets 106 , 108 are shown in assembled relationship in FIG. 3 . As previously described, the lower bracket member 124 is pivotably coupled to the upper bracket member 122 by an axle 174 extending through the aligned bores 138 , 172 of the nested ribs 136 , 166 . This permits the mounting brackets 106 , 178 to be positioned about the beam 102 with the projection 146 extending into the slot 118 . The upper and lower bracket members 122 , 124 are secured together, by, for example, a bolt or screw extending through the aligned openings 152 , 180 of the overlying bosses 150 , 176 , or other such clamping assembly.
[0047] The bushing 126 , as best shown in FIG. 3 , is constructed as a generally hollow tubular body having external threads at least about an upper portion of the bushing. The bushing 126 is adapted to be threadingly engaged within the threaded opening 134 within the upper bracket member 122 . The lower end of the bushing 126 is provided with an enlarged knob 188 . The knob 188 facilitates rotation of the bushing 126 , by hand, so as to advance and retract the bushing within the upper bracket member 122 . The bushing 126 is operative for supporting an electronic device by coupling same via, for example, a coupling device such as a tilter device 112 , forearm extension, extension arm or other such coupling device. The tilter device 112 is partially shown in FIG. 3 having a downwardly depending shaft (not shown) received within the upper opening provided within the bushing 126 . The adjustability of the bushing 126 is operative for raising and lowering the height or elevation of the electronic device which is coupled to the mounting bracket 106 , 108 . This is useful to align each of the electronic devices at the same elevation.
[0048] Referring to FIG. 7 , there is illustrated the mounting brackets 106 , 108 coupled to a beam 102 . In this regard, the upper and lower bracket members 122 , 124 are pivotably opened to receive the beam 102 . The upper bracket member 122 is positioned about the top half of the beam 102 with the projection 146 captured within the slot 118 . The projection 146 temporarily attaches the upper bracket member 122 to the beam 102 while the lower bracket member 124 is pivoted into a closed position encircling the beam. A threaded bolt received within the aligned bosses 150 , 176 brings the upper and lower bracket members 122 , 124 together in a clamping action about the beam 102 . Prior to final clamping, the brackets 106 , 108 can be slid along the beam 102 with projection 146 extending within the slot 118 to position the bracket at the desired location. Once positioned, the mounting brackets 106 , 108 are firmly secured to the beam by tightening the bolt or other clamping assembly as previously described.
[0049] A flat screen monitor 110 is coupled to each of the mounting brackets 106 , 108 via, for example, a tilter device 112 . However, other coupling devices such as an extension arm, forearm extension or other suitable assembly may be used as disclosed in U.S. Pat. No. 6,609,691. As shown in FIG. 1 , the bushing 126 is used to raise or lower each of the monitors 110 so that they are arranged at the desired elevation. In the preferred embodiment, each of the monitors 110 are arranged in a common horizontal plane with their upper and lower edges in alignment with one another. The height adjustment of each of the monitors 110 is achieved by rotating the bushing 126 via knob 188 . Any number of mounting brackets 106 , 108 may be coupled to the beam 102 , depending upon its length, to accommodate a plurality of monitors 110 or other electronic device.
[0050] Referring to FIG. 8 , the upper and lower bracket members 122 , 124 have planar inner curved surfaces 142 , 162 forming a cylindrical shape. As the beam 102 has a radius of curvature, the outer surface of the beam engages the inner curved surfaces 142 , 162 of the upper and lower bracket members 122 , 124 generally at a single midpoint identified by reference numeral 190 . The ribs 158 , 182 by extending from the side edges of the inner curved surfaces 142 , 162 engage the outer surface of the beam 102 at two spaced apart circumscribing locations. The engagement of the ribs 158 , 182 with the beam 102 provides enhanced mechanical coupling of the mounting brackets to the beam via the compressive force exerted thereon by the upper and lower bracket members 122 , 124 . This simplifies the construction of the mounting brackets. In an alternative embodiment, the curved inner surfaces 142 , 162 could be in the nature of a compound curve to accommodate both the cross-sectional shape of the beam 102 , as well as its radius of curvature.
[0051] Referring to FIG. 9 , there will now be described the construction of a mounting bracket 104 in accordance with another embodiment of the present invention. As previously described, the mounting brackets 106 , 108 are adapted to slide along the beam 102 for positioning at a desired location. The mounting bracket 104 , on the other hand, is adapted to be positioned at a fixed predetermined location along the beam 102 . To this end, the mounting bracket 104 is provided with a depending projection 192 extending away from the inner curved surface 142 of the upper bracket member 122 . The projection 192 may have a shape conforming to the shape of a corresponding opening (not shown) provided within the beam 102 . For example, projection 192 has a circular shape to be received within a circular opening within the beam 102 . However, it is noted that a circular projection 192 will fit within a square or polygonal shaped opening within the beam 102 . The opening within the beam 102 is formed at one or more predetermined locations for coupling the mounting bracket 104 thereat. It is also contemplated that the projection 192 can be provided extending from the lower bracket member 124 if desired. The construction of the mounting bracket 104 to include projection 192 typically obviates the need for providing a projection 146 as described with respect to mounting brackets 106 , 108 which is adapted to be received within the slot 118 of the beam 102 . Although only one projection 192 is illustrated, it is to be understood that spaced apart projections can also be incorporated into the mounting bracket 104 . A downwardly depending shaft 194 extends outwardly from the lower bracket member 124 . The shaft 194 is adapted to be received within a stand 116 for supporting the beam 102 in a horizontal orientation as shown in FIG. 1 . Generally, in all other respects, mounting bracket 104 is similar in construction to mounting brackets 106 , 108 .
[0052] Mounting bracket 104 , in one embodiment, is positioned centrally along the beam 102 at its mid point to support the beam via a stand 116 supported on the floor 114 , or attached to the ceiling, or a vertical wall. It is also contemplated that the beam 102 can be supported from a desk or other structure as may be desired. It is contemplated that the beam 102 may be supported by the use of a plurality of mounting brackets 104 arranged at spaced apart locations, each coupled to a stand 114 or other support structure, with or without the use of the slideable mounting brackets 106 , 108 . Accordingly, the mounting brackets 104 , 106 and 108 may be used in combination with each other for supporting an electronic device such as a flat screen monitor 110 and the like at various locations along the beam 102 .
[0053] Referring to FIG. 10 , there is illustrated another embodiment of a mounting bracket 196 . The mounting bracket 196 is of similar construction to mounting bracket 106 , 108 as previously described. The mounting bracket 196 is constructed to include a removable projection 198 which is shown in greater detail in FIG. 11 . The projection 198 is formed as a flat body having a u-shape by virtue of a pair of spaced apart legs 200 , 202 . The legs 200 , 202 are sized and shaped to be received within the slot 118 of the beam 102 .
[0054] The projection 198 is located between the free ends of the upper and lower bracket members 122 , 124 whereby the legs 200 , 202 extend inwardly into the bore 168 formed by the upper and lower bracket members. The main body of the projection 198 is attached to either an upper or lower boss 204 , 206 of the mounting bracket 196 having openings 208 in alignment with corresponding openings 210 within the projection 198 . A screw, bolt or other fastening member may be inserted through the aligned openings for securing the projection 198 to either the upper bracket member 122 or lower bracket member 124 . Generally, in all other respects, the construction of the mounting bracket 196 is similar to the mounting brackets 106 , 108 . Although the projection 198 has been disclosed as having U-shaped, the projection may also be constructed as a rectangular body simulating projection 146 .
[0055] A mounting bracket 212 in accordance with another embodiment of the present invention is shown in FIG. 12 . The mounting bracket 212 is constructed to accommodate a beam 102 provided with an outwardly projecting longitudinally extending rib 214 , as opposed to a slot 118 . In this regard, the inner curved surface 142 , 162 of either of the upper or lower mounting bracket members 122 , 124 is provided with a corresponding elongated opening 216 . Generally, in all other respects, the mounting bracket 212 is similar in construction to the aforementioned mounting brackets.
[0056] Referring to FIG. 13 , there is illustrated another embodiment of a mounting bracket 218 . Unlike the previously described mounting brackets, mounting bracket 218 is not intended to couple an electronic device thereto, but rather, to couple the beam 102 to, for example, stand 116 or other supporting structure or device. The mounting bracket 218 includes an upper bracket member 220 and a lower bracket member 124 . The construction of the lower bracket member 124 has been previously described with respect to FIG. 6 . As shown in FIG. 13 , the lower bracket member 124 includes a projection 146 and a downwardly depending shaft 194 as described with respect to the mounting bracket shown in FIG. 9 . The upper bracket member 220 is similar in construction to the upper bracket member 122 as described with respect to FIGS. 4 and 5 , but for the projection 146 and threaded opening 134 . However, as previously described, the projection 146 may be incorporated in either the upper or lower bracket members. The upper bracket member 220 is devoid of threaded opening 134 , as the mounting bracket is not intended to be coupled to an electronic device. The upper bracket 220 member is constructed to be pivotably attached to the lower bracket member 124 in lieu of the upper bracket member 122 having the threaded opening 134 . This minimizes the number of components required to be inventory when assembling a mounting bracket. As such, the lower bracket member 124 may be coupled to either of the upper bracket members depending upon the application of the mounting bracket.
[0057] Mounting bracket 218 allows for the independent mounting of electronic devices to the beam 102 , separate and apart from the mounting brackets used for mounting the beam to a support. This facilitates the adjustment of the electronic devices relative to each other along the beam 102 . That is, manipulation of the mounting bracket to adjust an electronic device does not affect the position or attachment of the mounting bracket used to attach the beam 102 to a support.
[0058] Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.
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A mounting apparatus includes a horizontally supportable beam and one or more mounting brackets for coupling an electronic device thereto. The beam is supportable from any number of support surfaces. The mounting brackets are provided with a projection to prevent twisting of the bracket during installation on the beam. One or more circular ribs within the bracket accommodate the use of curved beams. The mounting brackets enable positioning of the electronic device longitudinally along the beam at predetermined positions.
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BACKGROUND OF THE INVENTION
This invention relates generally to a safety switch for a gas burner, and more particularly, it relates to an active safety switch for a gas burner that can restore actively to prevent the ignition trigger from being pulled arbitrarily or from keeping enabled constantly for enhancement of security.
Usually, a gas burner will continuously burns as long as it is kindled and switch is kept open. For snuffing the gas burner out, a user has to take an action to close the gas switch, or in the case where the gas switch is interacted with a trigger, the flame is extinguished automatically as soon as the trigger is released. However, under either case mentioned, the gas burner lacks an active safety switch for the prevention of accidental ignition or any unnecessary conflagration.
In using an existing gas burner, which is generally provided with an auxiliary closing mechanism, a user should not forget to have the auxiliary closing mechanism effectuated to disable the trigger and ensure safety when he puts out the gas burner, or a disaster beyond compensation might be incurred if the trigger is pulled by a child or somebody else who is ignorant to danger of the gas burner.
In view of abovesaid imperfections, after years of constant effort in research, the inventor of this invention has consequently developed and proposed an improved mechanism pertaining to the subject matter for prevention of unnecessary accidents in using a gas burner.
SUMMARY OF THE INVENTION
The primary object of this invention is to provide an active safety switch for gas burner that can restore actively to prevent the ignition trigger from being pulled arbitrarily or from keeping enabled constantly to ensure safety in using a gas burner.
For more detailed information regarding this invention together with further advantages or features thereof, at least an example of preferred embodiment will be elucidated below with reference to the annexed drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The related drawings in connection with the detailed description of this invention to be made later are described briefly as follows in which:
FIG. 1 is a three-dimensional schematic view of this invention;
FIG. 2 is a three-dimensional exploded view of this invention;
FIG. 3 is a cutaway sectional view taken along line III—III in FIG. 1;
FIG. 4A is an action diagram of an active safety switch of this invention;
FIG. 4B is another action diagram of the active safety switch of this invention; and
FIG. 4C is yet another action diagram of the active safety switch of this invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
As shown in FIG. 1 through FIG. 3, a gas burner 1 mainly comprises a handgrip 11 , a top strap 12 on the handgrip 11 , a valve 13 underneath the top strap 12 , a safety switch 14 at rear end of the top strap 12 , a positioning pin 16 penetratingly anchored in the top strap 12 , a trigger 15 disposed at a front lower end of the top strap 12 , and a piezoelectric element 17 located between the valve 13 and the handgrip 11 .
A gas tank 111 having a gas inlet pipe 112 is placed in the handgrip 11 .
A switch slide channel 121 formed at one end of the top strap 12 is provided with a protrusion block 122 situated at inner upper edge of the switch slide channel 121 , and a positioning hole 123 is perforated at both lateral faces of the stop strap 12 , and further, an adjustment slot 124 is reserved at rear end of the top strap 12 .
The valve 13 is used to close, open, and adjust the gas flow, wherein a propping rod 131 for opening or closing gas flow is arranged at a lower end of the valve 13 ; an adjustment button 132 is disposed at tail end of the valve 13 ; and, the adjustment button 132 is sleeve-jointed with an adjustment knob 133 for adjusting flame of the gas burner 1 .
The safety switch 14 disposed in the switch slide channel 121 of the top strap 12 comprises a driving block 141 and a pressing block 143 secured to the driving block 141 , wherein a protrusion rod 144 on the pressing block 143 penetrates through and slightly projects over a through hole 142 of the driving block 141 ; an extension arm 146 having a protrusion rod 147 protrusively situated at its one end face and sleeve-jointed with a resilient body 149 is disposed at an end face of the driving block 141 ; a stop portion 145 is extended along both lateral faces of the pressing block 143 to seemingly prop the protrusion block 122 of the top strap 12 ; and, a stop block 148 is protrusively arranged on a lateral face of the pressing block 143 .
Moreover, the lower end of the trigger 15 is a pressing portion 151 , wherein a positioning groove 155 is formed at a lateral face of top edge of the pressing portion 151 and the other lateral face is a prop-and-tug portion 152 ; the top edge of the prop-and-tug portion 152 is extended to form an extension piece 153 whose tail end seemingly props the stop block 148 of the safety switch 14 ; and, a wedged groove 154 is formed in top face of the extension piece 153 .
The positioning pin 16 is penetratingly disposed in the positioning hole 123 of the top strap 12 and is transversely laid on the pressing portion 151 of the trigger 15 , and besides, a first and a second pressing head 161 , 162 are placed at two ends of the positioning pin 16 respectively.
The piezoelectric element 17 used for creating sparks is a switch with an extended ignition line 171 , and a start portion 172 of the piezoelectric element 17 is in contact with the prop-and-tug portion 152 of the trigger 15 .
For keeping the gas burner 1 under flame-spouting state, a user is supposed to poke the positioning pin 16 to another side, and at this moment, the first pressing head 161 at one end of the positioning pin 16 is inserted in the positioning groove 155 for positioning the trigger 15 to allow continuous supply of the gas. When the second pressing head 162 is pressed, the first pressing head 161 will detach from the positioning groove 155 of the trigger 15 to shut down the gas supply.
Referring to FIG. 4 A through FIG. 4C, when the protrusion rod 144 of the safety switch 14 is pressed, the stop portion 145 which normally props the protrusion block 122 of the top strap 12 will be separated to push the driving block 141 of the safety switch 14 upwards. At this moment, the trigger 15 which normally props the stop block 148 of the pressing block 143 will move sideward, and the prop-and-tug portion 152 is supposed to push the piezoelectric element 17 to start and create sparks at a sparking end 173 of the ignition line 171 . Meanwhile, the propping rod 131 of the valve 13 entrapped in the wedged groove 154 of the extension piece 153 is to be propped up to release the gas in the gas tank 111 via the gas inlet pipe 112 for being kindled by the created sparks.
In short, as a safety switch is available, the trigger of the gas burner cannot be pulled arbitrarily, and because it can be restored actively, any accidental pull of the trigger is prevented. Besides, a positioning pin of this invention is controllable for continuous supply of the gas without needing pulling the trigger continuously.
Although, this invention has been described in terms of preferred embodiments, it is apparent that numerous variations and modifications may be made without departing from the true spirit and scope thereof, as set forth in the following claims.
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An additional active safety switch for gas burner with active restoring capability is provided to actively prevent the ignition trigger of the gas burner from being pulled arbitrarily or from keeping enabled constantly for enhancement of security.
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FIELD OF THE INVENTION
The present patent document relates in general to enhancing photographic images by removing localized glare regions, specifically those due to direct reflection from a flash system.
BACKGROUND OF THE INVENTION
Both professional and amateur photographers are familiar with the problem of glare, which is a very harsh bright light that may cause regions of total or near-total overexposure in photographic images. Glare may occur due to light reflections from a wide variety of objects, including flat glass surfaces such as windows, mirrors, and aquariums, as well as eyeglasses, TV sets, moving water, chrome on cars, and facets on jewelry. Reflective items being photographed for auction purposes for example often require a surrounding diffuse lighting screen to allow clear photography. Glare may also be caused by very intense point-like light sources such as studio, theatrical, or stadium lights, the sun, and Christmas tree lights. Reflections and point-like light sources may also cause lens flare-related image artifacts, as is known in the art.
The light from a photographic flash reflecting back to the camera, typically very directly from flat surfaces, is however the most common cause of image glare. Amateur photographers in particular routinely have problems with flash-related artifacts in their images, especially when using a camera that has a fixed flash system near the lens. Underwater photography is particularly challenging because a flash is nearly always required.
Photographic flash systems may be used to successfully augment available light, but such use is not without complications, even for professionals. Flash-based image artifacts may not be noticed nor their impact on image quality fully appreciated at the time an image is taken. Getting the best overall exposure from the combination of available light and flash illumination is not always easy. As a result, photographers sometimes take bracketed images, wherein the exposure level for each image is varied both above and below a particular setting. The photographer must hope that one of the images will prove to be adequately lit overall and not marred by artifacts. Otherwise, the typical alternative is to painstakingly manually retouch photos, often using various software tools for assistance. Unfortunately, this practice may be very time intensive and may produce rather crude results. Therefore, detrimental image artifacts may discourage the use of flash systems, even with bracketing and software retouching.
As a result, there is a need for a tool to automatically remove glare artifacts from photographic images, particularly those pictures taken with a flash unit.
SUMMARY OF THE EMBODIMENTS
A system, method, business method, and computer program product for automatic image glare removal are disclosed and claimed herein. Exemplary embodiments acquire images from at least two different locations, preferably simultaneously, from one or more cameras, and digitize them if necessary. Recognition of a fully overexposed area or known test glare patterns then leads to a precise glare pattern identification. The exemplary embodiments then process the images to remove the glare pattern by subtraction of the glare pattern from at least one image and substitution or intermixing of corresponding data from a related image not identically marred by glare. The substituted data typically comprises chrominance data, which may be from a luminance-adjusted exposure-bracketed image. A camera, a local personal computer, or a networked server may perform the processing, and then output the processed image. The business method includes automated image glare removal via a free or fee-based per-transaction or subscription service.
As described more fully below, the apparatus and processes of the embodiments disclosed permit automatic image glare removal. Further aspects, objects, desirable features, and advantages of the apparatus and methods disclosed herein will be better understood and apparent to one skilled in the relevant art in view of the detailed description and drawings that follow, in which various embodiments are illustrated by way of example. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not intended as a definition of the limits of the claimed invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 depicts an image of an object displaying a typical photographic image glare pattern to be removed by embodiments of the invention;
FIG. 2 depicts an enlargement of the glare pattern of FIG. 1 to be removed by embodiments of the invention;
FIG. 3 depicts an embodiment of the invention that captures at least two images of an object from different locations;
FIG. 4 depicts a flow diagram of a process for an embodiment of the invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
Referring now to FIG. 1 , an image 100 of a hardhat is shown, displaying a typical photographic image glare pattern 102 to be removed by various embodiments. The hardhat is an exemplary photographic subject that has a smooth shiny surface that strongly reflects incoming illumination back towards the viewer from at least one point. Image 100 is the input image to be processed by the embodiments.
Referring now to FIG. 2 , an enlargement of the glare pattern 102 of FIG. 1 to be removed by embodiments is shown. Glare pattern 102 includes a central region 104 that is often completely overexposed, i.e. appears to be completely white regardless of most contrast and brightness adjustments. Glare pattern 102 may also include an outer partially overexposed radial region, shown here as item 106 . Such a region often appears more distinctly in images with reflections from curved surfaces than flat surfaces.
Exemplary embodiments identify glare patterns 102 automatically, so they may be processed separately from the rest of image 100 . Various ways exist to identify glare patterns 102 in images. First, completely overexposed image regions 104 may serve as readily detectable glare pattern indicia. Second, outer partially overexposed radial regions 106 surrounding such completely overexposed central image regions 104 may help verify the detection of a glare pattern. Third, test images obtained during camera design and manufacture may yield glare patterns that may be stored and characterized, along with lens flare patterns. Point reflectors photographed against a black background at various locations in the image field may yield a good model of glare for each lens used to capture images, including lens flare artifacts. Each lens in a multi-lens camera may have a different glare model, as each lens may for example have a different geometric relationship to a flash source, leading to a different “flash bounce”. Multiple flash sources may be employed, each potentially causing different glare patterns 102 . Finally, flash sources may have known color spectra and beam patterns that may be used to identify portions of a glare pattern 102 in an image that are not completely white (e.g. the partially overexposed radial regions 106 ).
Referring now to FIG. 3 , a diagram of an embodiment that captures at least two images of an object from different locations is shown. Object 300 (shown with scalloped edges to note that it is an actual object versus an image) is depicted as seen in ambient light. A second fill-in light source will to be used to better illuminate object 300 , but of course this raises the possibility of problems with glare. Cameras 302 and 304 acquire images 100 and 200 , respectively, from two distinct spatial points. Cameras 302 and 304 may actually comprise two separate lenses in a single camera housing (not shown). Alternately, the embodiment may capture more than two images, as is often the case with so-called “3D” cameras used for stereo photography. Indeed, one embodiment employs a 3D camera per se. The exemplary embodiment preferably captures images simultaneously, to prevent intervening motion from complicating the glare removal process.
Cameras 302 and/or 304 may be film cameras, digital cameras, infrared cameras, night vision cameras, or video cameras that provide images sampled from video output. The cameras may have crossed polarizing lenses for partial glare reduction, and may be traffic cameras used by law enforcement for example at intersections to clearly photograph vehicle license plates. The cameras may also be mounted on any vehicle such as a car, a truck, an airplane, and an unmanned aerial vehicle. The cameras may be part of a heads-up display that provides improved vision for drivers and pilots, for example, to help reduce accidents. The cameras may also be part of an “augmented reality” system that provides improved telepresence for remotely operated vehicles.
Image 100 is the image previously depicted in FIG. 1 . Image 200 differs primarily in the location of the glare pattern 202 within the image, due mainly to the different point of view or spatial location from which image 200 was acquired. The region of image 100 marred by glare pattern 102 is preferably unmarred in a corresponding portion of image 200 , as shown. The unmarred image information corresponding to glare pattern 102 may be sampled from image 200 and used to replace or augment the portion of image 100 marred by glare. Output image 302 is thus a version of image 100 that has had glare pattern 102 removed by an embodiment. Note that in general any combination of images may be used to provide unmarred image information for glare removal from any particular target image for any glare patterns.
Image 200 will not be completely identical to image 100 , but may be adjusted by the embodiments to compensate for several factors prior to sampling of the corresponding image portion. First, since image 200 was taken from a different location, it will need to be geometrically adjusted for perspective or keystone distortion; this adjustment method is known in the art. Second, image 200 may not have the same overall brightness as image 100 , so its luminance may need to be adjusted to match as closely as possible; this adjustment is also known in the art.
Image 200 may contain glare patterns of its own (e.g. item 202 ), and if these spatially overlap the glare patterns of image 100 (e.g. item 102 ) then image 200 may not be suitable for use in the glare removal process. Embodiments may make this determination from the adjusted version of image 200 . Once the exemplary embodiments find the image area of image 200 corresponding to glare pattern 102 to be useful, they effectively overlay or intermix chrominance information from that corresponding area with the overexposed and/or partially overexposed portions of glare pattern 102 . The normal unmarred color from image 200 thus replaces to some extent the marred color from image 100 , removing glare pattern 102 .
Further embodiments may also employ bracketing techniques, which are known in the art, to enhance image quality. Bracketing generally refers to taking multiple photographs of a subject, each with exposure levels both deliberately above and below an estimated optimal setting. The intended result is to cover the full brightness range for most or all parts of the image area for maximum dynamic contrast. Exemplary embodiments may better identify glare patterns by comparing bracketed image sets; darker, more underexposed images may have smaller glare patterns 102 , particularly with less prominent partially overexposed radial regions 106 .
Referring now to FIG. 4 , a flow diagram of a process for an embodiment is shown. Process 400 begins from a START state, which is typically when a photographer triggers a camera setup for example. In step 402 the process acquires a first image from a first location. In step 404 , the process acquires a second image from a second location that is different from the first location. The second image is preferably acquired at substantially the same time as the first image. Additional images may also be captured (not shown). In step 406 , the process identifies the glare patterns in the first image. These glare patterns are regions that lack sufficient descriptive information about the object being photographed due to overexposure from reflected light. The process seeks to correct this difficulty and increase image quality by estimating the insufficient information from corresponding portions of other similar images.
In step 408 , process 400 adjusts the second image to render it more useful for providing the descriptive information needed to remove glare patterns from the first image. Next, in step 410 , the process identifies in the second image those regions corresponding to the glare pattern locations in the first image. In step 412 , process 400 substitutes or intermixes identified regions of the second image to remove glare patterns from the first image. Finally, the process outputs the processed first image in step 414 and the process ends in step 416 .
A camera may perform the glare pattern removal processing if it has sufficient computing power. In other exemplary embodiments, a local computer such as a personal computer into which images are transferred, or a server computer performs the processing. The processing computer may be connected to the camera via a wired or wireless network. The images may be initially non-digital, but are digitized by embodiments as needed prior to processing. The processing computer may return the processed image directly to the camera for storage, or otherwise output the processed image, e.g. via color printer, e-mail, or online storage site. Other exemplary embodiments may perform the processing as a business method, wherein a user is provided the processing as a free promotion or pays a fee for the glare removal service, for example on either a per-processing or subscription basis.
As used herein, the terms “a” or “an” shall mean one or more than one. The term “plurality” shall mean two or more than two. The term “another” is defined as a second or more. The terms “including” and/or “having” are open ended (e.g., comprising). Reference throughout this document to “one embodiment”, “certain embodiments”, “an embodiment” or similar term means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of such phrases in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner on one or more embodiments without limitation. The term “or” as used herein is to be interpreted as inclusive or meaning any one or any combination. Therefore, “A, B or C” means “any of the following: A; B; C; A and B; A and C; B and C; A, B and C”. An exception to this definition will occur only when a combination of elements, functions, steps or acts are in some way inherently mutually exclusive.
In accordance with the practices of persons skilled in the art of computer programming, embodiments are described below with reference to operations that are performed by a computer system or a like electronic system. Such operations are sometimes referred to as being computer-executed. It will be appreciated that operations that are symbolically represented include the manipulation by a processor, such as a central processing unit, of electrical signals representing data bits and the maintenance of data bits at memory locations, such as in system memory, as well as other processing of signals. The memory locations where data bits are maintained are physical locations that have particular electrical, magnetic, optical, or organic properties corresponding to the data bits.
When implemented in software, the elements of the embodiments are essentially the code segments to perform the necessary tasks. The non-transitory code segments may be stored in a processor readable medium or computer readable medium, which may include any medium that may store or transfer information. Examples of such media include an electronic circuit, a semiconductor memory device, a read-only memory (ROM), a flash memory or other non-volatile memory, a floppy diskette, a CD-ROM, an optical disk, a hard disk, a fiber optic medium, a radio frequency (RF) link, etc. User input may include any combination of a keyboard, mouse, touch screen, voice command input, etc. User input may similarly be used to direct a browser application executing on a user's computing device to one or more network resources, such as web pages, from which computing resources may be accessed.
While the invention has been described in connection with specific examples and various embodiments, it should be readily understood by those skilled in the art that many modifications and adaptations of the automatic glare removal tool described herein are possible without departure from the spirit and scope of the invention as claimed hereinafter. Thus, it is to be clearly understood that this application is made only by way of example and not as a limitation on the scope of the invention claimed below. The description is intended to cover any variations, uses or adaptation of the invention following, in general, the principles of the invention, and including such departures from the present disclosure as come within the known and customary practice within the art to which the invention pertains.
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A system, method, computer program product, and business method for automatic image glare removal. Glare is often caused by direct reflection of a photographic flash. Images are acquired from at least two different locations, possibly simultaneously, and from one or more cameras, and digitized if necessary. A glare pattern is identified, typically by recognition of a fully overexposed area or known test glare patterns. The images are processed to remove the glare pattern by subtraction of the glare pattern from at least one image and substitution of corresponding data from a related image not identically impacted. The substituted data typically comprises chrominance data, which may be from a luminance-adjusted exposure-bracketed image. The processing may be performed by a camera, a pc, or a networked server, and the processed image is output. The business method includes automated image glare removal via a fee-based per-transaction or subscription service.
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RELATED APPLICATION
[0001] This application claims priority to and incorporates by reference U.S. Provisional Application Ser. No. 61/746,011, filed Dec. 26, 2012.
TECHNICAL FIELD
[0002] This disclosure relates to disperser plate segments.
BACKGROUND OF THE INVETNION
[0003] Recovered paper and packaging materials are known as “fiber stock” to those skilled in the art. Fiber stock is generally subjected to several processes designed to remove ink and toner in the case of copy paper. Contaminants such as plastics generally referred to as “stickies” by those skilled in the art. The removal processes are not completely efficient and the residual ink, toner, and stickies are typically dispersed to avoid the stickies adhering to parts of the paper machine, which can cause holes or weak spots in new paper. The agglomeration and accumulation of stickies on the paper machine can cause idle time thereby increasing the cost of the manufacturing process itself. Residual ink particles typically appear as specs in the reconstituted paper, which can lower its value considerably.
[0004] A machine called a disperser (or a disperger) can be used to reduce the size of the ink and stickie particles so that in subsequent paper machine operations, paper qualities may be minimally impacted. Disperser machines generally have two circular discs facing each other. One disc, generally referred to as a rotor, can be rotated while the other disc, generally referred to as a stator, is generally stationary. Conical machines can also be used where a rotor cone can move while a stator cone generally remains stationary.
[0005] On the faces of the discs or cones may be mounted plate segments having pyramids or teeth mounted in tangential rows. The rows are at radii generally chosen to allow the rotor and stator teeth to intersect a plane between the discs or cones so that the fiber passing from the center of the stator to the periphery of the discs or cones generally receives impacts from the rotor teeth as they pass close to the stator teeth. The clearance between rotor and stator teeth is on the order of about 1 to about 12 mm so that the fibers are generally not cut but rather are typically severely and alternately flexed. This action usually breaks the ink and toner particles into smaller particles and also breaks down the stickie particles. It is also generally thought that the fresh smaller sticky surfaces collect fine fiber particles and may be further passivated as smaller particles. Increasing the number of flexures the fibers experience has generally been shown to improve the unwanted particle reduction process. Adding more teeth generally improves the efficiency of the dispersion process but the size of the teeth that can be manufactured at reasonable costs limits this number. A conventional disperser plate is described in U.S. Pat. No. 7,172,148 where a single groove extends from the tooth top surface to a point intermediate the top surface and the channel base surface.
[0006] For conical dispersers, where the cones contain the pyramids or teeth, the same action usually occurs and the designs of the teeth are substantially the same as those for flat discs.
SUMMARY OF THE INVENTION
[0007] The efficiency of dispersion may be improved and the amount of ink, toner, and stickies entering a paper-making machine may be reduced by increasing the number of edges that contact the fiber stock. By configuring grooves into one or more sides of the teeth, the amount of contact edges may be increased while substantially maintaining the structural integrity of the teeth. The plane defined by sides of the teeth may be known as “face surfaces” throughout this disclosure.
[0008] A disperser plate segment for removing contaminants from fiber stock, the segment comprising: radially inner and radially outer edges, multiple radially concentric rows of teeth, each row of teeth having multiple teeth defining multiple channels disposed intermediate the teeth, each of the channels having a lower channel base surface and each of the teeth comprising: an top surface, at least one face surface extending from the channel base surface to the top surface, and wherein at least one of the face surfaces comprises at least two grooves.
[0009] At least one tooth may have multiple grooves on at least one of its surfaces. The additional grooves to the faces surfaces of the tooth may help to increase circumferential friction applied to the material in between the intermeshing row of teeth thereby improving separation of the contaminants from the desired material. By using a groove angled relative to the vertical axis of the face of the tooth surface, the angled groove may help to redirect material along the axis of the height of the teeth, as the teeth move material vertically between the channel base surface and the tooth top surface.
[0010] The inner and outer surfaces of each tooth may extend at an acute angle from the channel base surface to the top surface, such that the tooth may have a truncated pyramid shape. With multi-grooved teeth, a segment of the top surface may separate the inner face and outer face surface grooves from each other when the grooves extend to the top surface of the tooth. Additionally, for multi-grooved teeth, a segment of the top surface may separate the grooves along a face surface; this face surface may be an inner face surface or outer face surface. In some example embodiments, the face surface may be the side surfaces of the teeth that define a channel between two teeth.
[0011] In some exemplary embodiments, the grooves on the inner face surface and outer face surface may be tapered. For example, for at least one of the grooves, the width of the groove may taper outward on the face surface from the top surface toward the channel base surface. In another example embodiment, the depth of the groove may taper from the face surface into or inward to the tooth mass as the groove extends from the top surface toward the channel base surface. In example embodiments involving a tapered groove, a segment of the top surface may separates the inner face and outer face surface grooves from each other.
[0012] In some embodiments the width of at least one of the grooves may change along its length. For example, at least one of the grooves may taper outwardly on the tooth face surface. In other exemplary embodiments, the depth of at least one of the grooves may change along its length. For example, the depth of at least one of the grooves may taper inward into the tooth face surface as the groove extends across the tooth face surface toward the channel base surface. In some exemplary embodiments, the grooves may not connect with each other through the teeth. In other exemplary embodiments, it is possible to have at least two of the grooves connect.
[0013] Each of the teeth may also have oppositely disposed leading and trailing edges. The grooves of the inner face surface of each tooth and the grooves of the outer face surface of each tooth may define additional leading edges and additional trailing edges.
[0014] In an exemplary embodiment of this disclosure, multiple grooves on the inner face or outer face surfaces of the teeth may extend the substantially similar lengths between the top surface and the channel base surface, that is from the top surface to a point intermediate the top surface and the channels base surface.
[0015] In another example embodiment of this disclosure, multiple grooves on the inner face surface or outer face surface of the teeth may extend the same lengths between the top surface and the channel base surface; for example, at least one of the grooves may extend from the tooth top surface to or substantially to the channel base surface.
[0016] In another example embodiment of the disclosure, multiple grooves on the inner face surface or outer face surface of the teeth may extend different lengths between the top surface and the channel base surface. For example, one or more grooves may extend from the top surface to the channel base surface, and one or more grooves may extend from the top surface to a groove lower most end point intermediate the top surface and the channel base surface, and one or more groves may extend from the channel base surface upward toward—but not to—the top surface, and one or more grooves can extend from below the top surface to a point intermediate the channel base surface.
[0017] In yet another embodiment, widths of the individual grooves on the inner face surface or outer face surface of teeth may vary. The widths of the individual grooves on the inner face surface or outer face surface may also vary among any individual tooth. For example, one groove may have a wider width than the remaining grooves on the face surface of the tooth. The lengths of each of the grooves, whether wide or narrow may be any of the previously identified lengths, e.g. the entire length from the top surface to the channel base surface or the length from the top surface to a point intermediate the top surface and the channel base surface or the length from the channel base surface to a point below the top surface. Moreover, one or more grooves can extend from below the top surface to a point intermediate the channel base surface.
[0018] In still another embodiment of the disclosure, the multiple tapered grooves of varying lengths (as described previously) may exist on the inner face surface or the outer face surface of the teeth.
[0019] In another embodiment of the disclosure, the grooves on the inner face surface or outer face surface may be angled relative to the vertical axis of the face of the tooth surface and each groove may be the same length or may be different lengths. The angled grooves may be the same width or different widths and may have tapering. Both the width and depth of the groove may be tapered. Conversely, either the width or depth of the groove may be tapered. The angle of the grooves may be about 5 degrees to about 60 degrees.
[0020] A disperser plate segment for removing contaminants from fiber stock has been conceived, the segment comprising: radially inner and outer edges and multiple of radially concentric rows of teeth; each row of teeth having multiple teeth defining multiple channels disposed intermediate the teeth; each of the channels having a lower channel base surface and each of the teeth comprising: a top surface, at least one face surface extending from the channel base surface to the top surface, the at least one face surface defining at least two grooves at an angle θ relative to the vertical axis of the face surface.
[0021] It is also possible to have the inner face surface with one embodiment of the disclosure and the outer face surface with a different embodiment or both the inner face and outer face surfaces may use the same embodiment of the disclosure. In yet another embodiment, any combination of previously described grooves on any of the surfaces of the teeth may be used.
[0022] A disperser plate comprising: multiple radially concentric rows of teeth, wherein each row may be configured to mesh between rows of teeth on an opposing plate; adjacent teeth of the radially concentric rows defining channels between the adjacent teeth, wherein the channels each are aligned with a respective row of teeth on the opposing plate, and multiple grooves on a face surface of each of the teeth in at least one of the concentric rows.
[0023] Additionally, the disperser plate may be segmented into disperser plate segments. In some embodiments, the disperser plate may have the teeth in at least one of the concentric rows each having an upper surface and the grooves extend from one of the channels to the top surface of the respective tooth. In at least some of the embodiments of the disperser plate, the depth of at least one of the grooves on each of the teeth may vary along the length of the groove. In some embodiments, the groove extends only partially along the height of the tooth and the grooves may be parallel. In other embodiments the grooves are oblique to a plane of rotation of the disperser plate. In at least some embodiments, the width of at least one of the grooves on each tooth differs from the width of another one of the grooves on the tooth.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The foregoing will be apparent from the following more particular description of example embodiments of the disclosure, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, with emphasis instead being placed upon illustrating embodiments of the disclosed device.
[0025] FIGS. 1 a , 1 b , and 1 c show a conventional disperser with plate segments.
[0026] FIG. 2 shows an exemplary face view of a tooth with multiple grooves of similar length and width.
[0027] FIG. 3 shows an exemplary face view of a tooth with multiple grooves having differing lengths.
[0028] FIG. 4 shows an exemplary face view of a tooth with multiple grooves having differing widths.
[0029] FIG. 5 shows an exemplary face view of a tooth having a groove with a tapered width.
[0030] FIG. 6 shows an exemplary face view of a tooth having a groove with a tapered depth.
[0031] FIG. 7 shows an exemplary top view of the tooth having an asymmetrical shape to the depth tapering.
[0032] FIG. 8 is the mirror image of FIG. 6 .
[0033] FIG. 9 shows an exemplary top view of the tooth with multiple grooves having different shapes.
[0034] FIG. 10 shows an exemplary face view of a tooth with angled grooves.
DETAILED DESCRIPTION OF THE INVENTION
[0035] Increasing the number of contact edges available for the material may improve the breaking down of the contaminants and stickies in the fiber stock and may improve the efficiency of a disperser machine.
[0036] A disperser plate segment according to any of the embodiments of the disclosure has at least one of the teeth of the inner face surface or outer face surface comprising at least two grooves. The teeth with at least two grooves can be any combination of groove lengths, groove widths, groove shape, tapered width grooves, tapered depth grooves, or angled grooves on the inner face surface or outer face surfaces.
[0037] Although the grooves are depicted as ovular, cylindrical, or conical in the figures, the grooves may have triangular, pyramidal, or quadrilateral shapes in other embodiments.
[0038] FIGS. 1 a , 1 b , and 1 c show a conventional plate segment 10 for a disperser. In FIG. 1 a , the conventional plate segment 10 is a stator plate segment 15 . Each conventional plate segment 10 is typically a molded metal piece formed as a pie-shape, such as an annularly truncated wedge-shape, having a generally planar substrate. However, the conventional plate segment 10 may be circular or semi-circular and the substrate may be conical or partially conical. Each conventional plate segment 10 has an inner edge 22 towards the common center axis 19 of the disc to which the conventional plate segment 10 may be attached (disc not shown). Each conventional plate segment 10 also has an outer edge 24 near the periphery of the disc to which the conventional plate segment 10 may be attached (disc not shown). Each conventional plate segment 10 has concentric rows 26 of teeth 28 . People skilled in the art may refer to the teeth 28 as pyramids. The concentric rows 26 of teeth 28 are each at a common radial distance (see radii 32 ) from the common center axis 19 .
[0039] FIG. 1 b is a cross-sectional view of one of the stator plate segment 15 . As the fiber stock (not shown) contacts the stator plate segment 15 near the inner edge 22 of the stator plate segment 15 , the fibrous material may flow over concentric rows 26 of teeth 28 towards the outer edge 24 of the stator plate segment 15 .
[0040] FIG. 1 c is a cross-sectional view of a rotor disc 12 and a stator disc 13 arranged opposite to each other. The stator disc 13 has an annular array of the stator plate segments 15 and a rotor disc 12 has an annular array of rotor plate segments 14 .
[0041] The teeth 28 on rotor plate segments 14 intermesh with the rows of teeth on the array of stator plate segments 15 , as is shown in FIG. 1 c . The intermeshing teeth 28 intersect a radially extending plane in the gap 30 between rotor disc 12 and stator disc 13 .
[0042] The array of rotor plate segments 14 on the rotor disc 12 and the array of stator plate segments 15 on the stator disc 13 generally rotate about a common center axis 19 .
[0043] As the rotor disc 12 rotates, fiber stock (not shown) generally moves through the serpentine gap 30 between the arrays of stator plate segments 15 and rotor plate segments 14 as a pad of fiber material. The flexing and bending of the fiber stock as the pad moves over and between the teeth 28 dislodges stickies from fibers in the fiber stock.
[0044] The rotation of the rotor disc 12 and the rotor plate segments 14 apply a centrifugal force that moves the fiber stock straight through the gap 30 between the opposing arrays of plate segments. As the fiber stock moves radially beyond the outer edges 24 of the rotor plate segments 14 and stator plate segments 15 , the fiber stock enters a casing 31 of the disperser.
[0045] For similar elements, similar reference numbers are used for the remaining figures. FIG. 2 shows a face surface 140 of a tooth 100 having grooves 110 of substantially the same length. The grooves 110 can extend from the top surface 120 of the tooth 100 to the channel base surface 130 The width 150 and depth 160 of each groove 110 may be similar or substantially the same.
[0046] FIG. 3 shows a face surface 240 of a tooth 200 having grooves 210 of differing lengths. The grooves 210 may extend from the top surface 220 to the channel base surface 230 or from the top surface 220 to a point 255 intermediate the top surface 220 and the channel base surface 230 or from the channel base surface 230 to a point below the top surface 220 , or one or more grooves 210 can extend from below the top surface 220 to a point intermediate the channel base surface 230 , or any combination with at least one of the grooves 210 being a different length from the other grooves 210 , with the width 250 and depth of all grooves 210 being the same or substantially the same.
[0047] FIG. 4 shows face surface 340 of a tooth 300 having grooves 310 of the same lengths. In other embodiments, the lengths of the grooves may be different. The grooves 310 may extend from the top surface 320 to the channel base surface 330 or from the top surface 320 to a point intermediate the top surface and the channel base surface 330 or from the channel base surface 330 to a point below the top surface 320 , or one or more grooves 310 can extend from below the top surface 320 to a point intermediate the channel base surface 330 , or any combination with at least one of the grooves being a different length from the other groove or grooves 310 , with at least one of the grooves 310 being a different width 350 from the other groove or grooves 310 . The depth 360 of the groove 310 into the tooth 300 may vary, e.g., linearly, in a direction towards the top of the tooth or in an opposite direction. Further, the depth 360 of the grooves 310 may vary from groove 310 to groove 310 on the same tooth 300 .
[0048] FIG. 5 shows face surface 440 of a tooth 400 having a single groove 410 . Groove 410 may have a width 450 , which tapers from narrowest point at or near the top surface 420 and widest at or near the channel base surface 430 . There may be grooves 410 that have widths 450 tapering along the face surface 440 , while the depth 460 and lengths of the grooves 410 may remain constant or the depths 460 of the grooves may remain constant while the lengths of the grooves may vary.
[0049] FIG. 6 shows face surface 540 of a tooth 500 having a single groove 510 . Groove 510 has a first depth 560 which tapers from the top surface 520 to a second depth 570 at the lowest point of the groove 510 . The first depth 560 may be measured as the distance between the face surface 540 and the top internal backside 580 of the groove 510 at the top surface 520 . The lowest point of the groove 510 may be the point closest to the channel base surface 530 . The second depth 570 may be measured as the distance from the face surface 540 and the lowermost internal backside 590 of the groove 510 . The tapering of the groove 510 may increase from the first depth 560 to the second depth 570 and can be for example about 1 mm to about 10 mm, or possibly about 2 mm to about 10 mm, or possibly about 1 mm to about 3 mm, or possibly about 2 mm to about 5 mm and any dimension in between. There may be grooves 510 with varying tapered depths where the first depth 560 and the second depth 570 can be the same for each groove 510 or can be different for each groove 510 . In addition to having different depths in the grooves 510 , the depth of each groove 510 may taper. Further, the length of the grooves 510 on the face surface 540 may vary as the first depth 560 and second depth 570 varies. There may be a lowest most point of the groove 510 at or near the channel base surface 530 while the upper end of the groove 510 may be located at any point between the channel surface base 530 and the top surface 520 , or the groove 510 may extend from the top surface 520 to a point intermediate the channel base surface 530 , or have the groove 510 located along the face surface 540 but not extend to either the top surface 520 or the channel base surface 530 while having at least one groove 510 with a first depth 560 and a second depth 570 . While not shown in FIG. 6 , the depth of the groove may be greater in the top of a tooth 500 as compared to bottom of the tooth 500 .
[0050] FIG. 7 shows a top view of a tooth 600 having an asymmetrical shape to the depth tapering. On the left side 612 of the opening 621 , the angle from the face surface 640 to the innermost point of the groove 655 may be shallow and sharp such as less than about 90 degrees. On the right side 613 , the angle from the face surface 640 to the innermost point of the groove 655 may be about 90 degrees. In some embodiments, the angles from the front surface 640 to the innermost point of the groove 655 may by symmetrical. In other embodiments, the angles from the front surface 640 to the innermost point of the groove 655 may be asymmetrical.
[0051] FIG. 8 shows a top view of a tooth 700 having an asymmetrical shape to the depth tapering a mirror image of FIG. 7 . On the right side 712 of the opening 721 , the angle from the face surface 740 to the innermost point of the groove 755 may be shallow and sharp, such as less than about 90 degrees. On the left side 713 , the angle from the face surface 740 to the innermost point of the groove 755 may be about 90 degrees. In some embodiments, the angles from the front surface 740 to the innermost point of the groove 755 may by symmetrical. In other embodiments, the angles from the front surface 740 to the innermost point of the groove 755 may be asymmetrical.
[0052] FIG. 9 shows a top view of a tooth 800 when multiple grooves are used and may be any combination of the shapes shown in FIGS. 7 and 8 . As shown in FIG. 9 , opening 821 has the shape of the opening 621 (from FIG. 7 ). On the first shallow side 818 , the angle from the face surface 840 to the innermost point of the groove 855 may be shallow and sharp such as less than about degrees. On the sharp side 813 , the angle from the face surface 840 to the innermost point of the groove 855 may be about 90 degrees. Opening 822 has the shape of opening 721 (from FIG. 8 ). On the second shallow side 812 , the angle from the face surface 840 to the innermost point of the groove 855 may be shallow and sharp such as less than about 90 degrees. On the sharp side 813 , the angle from the face surface 840 to the innermost point of the groove 855 may be about 90 degrees. In other embodiments, grooves using at least one of the configurations from FIG. 7 or 8 may be used for at least one of the teeth.
[0053] FIG. 10 shows face surface 940 of a tooth 900 having a top surface 920 , a channel base surface 930 , and grooves 910 . The grooves 910 are positioned at an angle θ of between about 5 degrees and about 60 degrees. In other example embodiments, angle θ may be between about 10 degrees and about 60 degrees, or possibly about 30 degrees and about 60 degrees relative to the vertical axis of the face surface 940 of the tooth 900 . In some example embodiments, the angle θ may vary between at least one groove on the same tooth. In some example embodiments, the angle θ may vary among at least one groove on a different tooth on the disperser. The angle θ may allow edges of the grooves to engage fiber stock at different angles thereby increasing the number of edges that contact the fiber stock and altering the direction of the fiber stock in a manner that may improve dispersion. By contrast, the angle θ for conventional grooves in conventional disperser plate teeth is about zero degrees. Grooves 910 are shown as having differing lengths 965 and the same widths 950 . In some example embodiments, grooves 910 may also have the same depths (not shown). The grooves 910 may have differing widths 950 and the same lengths 965 and the same depths. In other example embodiments, the grooves 910 may have the same widths and differing heights. In another exemplary embodiment, the length of at least of the grooves may extend through the side face surface of at least one tooth. In some embodiments, the widths 950 of grooves 910 could taper from narrow to wide as grooves 910 move across the face surface 940 . In some embodiments, the depth may taper from shallow to deep as grooves 610 move across the face surface 940 . Combinations of the above embodiments are also possible.
[0054] While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.
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A disperser plate segment for removing contaminants from fiber stock, the segment comprising: radially inner and outer edges, multiple radially concentric rows of teeth, each row of teeth having multiple teeth defining multiple channels disposed intermediate the teeth, each of the channels having a lower channel base surface and each of the teeth having a top surface, at least one face surface extending from the channel base surface to the top surface, and wherein at least one of the face surfaces comprises at least two grooves.
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This is a continuation-in-part application of U.S. patent application Ser. No. 752,284 filed on July 5, 1985, now abandoned.
BACKGROUND OF THE INVENTION
Glass-enclosed atrium or greenhouse structures are being used with greater frequency in restaurants and commercial buildings as well as homes. While these structures have many aesthetic advantages and are pleasing architecturally, in direct sunlight they become practically uninhabitable with severe discomfort on the part of the occupants. Consequently, it is necessary to provide some sort of a shading device which may readily be raised or lowered. Because these structures typically involve a vertical wall of glass which, at its topmost portion is curved to a 45° angle with the upper portion extending at such an angle until it joins the conventional portion of the structure, ordinary shades or blinds will not function because they would hang in an unattractive, ineffective fashion because of the overhanging curved portion of the atrium.
Therefore, it is necessary to provide tracks on which the shades can be supported and, as a consequence, these atriums or greenhouses are usually constructed in sections with tracks spaced two or three feet apart. The shades are thus supported on transversely extending rods that ride in said tracks and the shades are usually permitted to descend by gravity and may be raised by hand or by means of a motorized device. In any case, the shades occasionally will stick in one or the other tracks so that the shades will be askew and cause an unattractive appearance. This can occur either when the shade is raised or when it is lowered.
Power driven devices are available to raise or lower the shades, but these are relatively expensive and in many applications, especially where the atrium or greenhouse is small, it is desirable to have the shades operated manually. The only device of the prior art with which applicant is familiar is U.S. Pat. No. 2,229,898, Pastva, which is an awkward device to use for raising or lowering blinds in these circumstances and involves separate pulls which would not function in the overhanging atrium or greenhouse configuration. Furthermore, this system does not permit self-leveling of the blinds in case they become stuck while being raised or lowered.
SUMMARY OF THE INVENTION
The subject invention is a manually operated device for raising or lowering shades on a glass-enclosed atrium or greenhouse wall which includes a self-leveling feature so that if a shade should get hung up at the bend portion of the atrium or greenhouse wall where the vertical portion joins the sloping portion or elsewhere, the device selfadjusts so that the shades will hang level in the raised or lowered position. The subject invention is susceptible of being operated in a multiple number of glass-enclosed atrium or greenhouse wall sections and is particularly useful in relatively small atrium or greenhouse wall installations.
The subject invention also contemplates a manually operated device for raising and lowering shades in a glass-enclosed atrium or greenhouse wall wherein the shade may be raised or lowered by grasping a single handhold on either side of the shade so the shade may be raised or lowered with one hand.
It is therefore an object of this invention to provide a device to raise and lower shades on an atrium or greenhouse wall.
It is a further object of this invention to provide such a device which will permit the shades to be self-leveling in their open or closed position.
It is a still further object of this invention to provide such a device which may be operated manually.
It is a still further object of this invention to provide such a device which may be operated by one hand.
Additional objects and advantages of the present invention will become more readily apparent to those skilled in the art when the following general statements and descriptions are read in the light of the appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a section of typical glass-enclosed atrium or greenhouse showing applicant's invention with the shades on the atrium wall in a closed position.
FIG. 2 is a perspective view of a corner section of the atrium or greenhouse wall showing applicant's invention as applied to a lower portion of the atrium wall showing the attachment to one side of the shade.
FIG. 3 is a schematic view of applicant's invention showing the relationship of the pulley and cords therein.
FIG. 4 is a detailed view of the portion of applicant's invention which is fixedly attached to the lower shade member on the opposite side from that shown in FIG. 2.
FIG. 5 is a cross-sectional view of the compartmentalized track portion of applicant's invention.
FIG. 6 is a perspective view showing the manner in which applicant's invention is attached to the upper portion of the atrium or greenhouse wall.
FIG. 7 is a perspective view of a variation of applicant's invention which permits the shade to be raised by one hand showing the lower portion of the shade supporting mechanism.
FIG. 8 is a section through member 15 of FIG. 2.
FIG. 9 is a side sectional view of member 15 shown in FIG. 8.
DETAILED DESCRIPTION OF THE INVENTION
Referring now more particularly to FIG. 1, the atrium or greenhouse wall is shown having mullions 10--10 provided with tracks 11--11 attached thereto. Shades 12--12 are shown in closed position.
Referring now more particularly to FIG. 2, mullion 10 and shade 12 are shown with shade 12 in closed position and with track 11 housing, in one portion, cord 13 which extends around lower pulley 14 and passes through and is slideably positioned in member 15, which is attached to shade 12, and slides in compartmentalized track 11, but may be adjusted upwardly or downwardly by means of handles 15a--15a because cord 13 is slideably positioned in member 15. Shade 12 is supported by rods 16--16 which in turn may be attached to hooks 17--17 which in turn slide in compartmentalized track 11. Rods 16--16 support the shades when the shades are in a semi-horizontal position.
Referring now more particularly to FIG. 3, cord 13 is shown passing over lower pulleys 14--14 on either side of an atrium or greenhouse window segment and around pulleys 18--18 and 19--19. It will be noted that cord 13 is fixedly secured to member 20 which in turn is secured to shade 12. It is important that cord 13 traverse pulley 14 in a different direction on one side of the shade than it does on the other side of the shade. Thus when an individual uses handles 15a--15a to grasp members 15 and 20 to raise or lower the shade 12, upward movement of member 20 will result in corresponding upward movement of member 15 and corresponding upward movement of shade 12, and if the shades become uneven since member 15 slidabely engages cord 13, the horizontal alignment may be readily adjusted.
Referring now more particularly to FIG. 4, member 20 is shown positioned in compartmentalized track 11, and cord 13 may be tied as at 22 to effectively make it an endless cord that also fixedly attaches cord 13 to member 20. Likewise, in operation if it is desired to lower shade 12, it is merely necessary to grasp handholds 15a--15a and pull down on them, remembering that the hand hold on member 15 may be raised or lowered if the device is uneven.
Referring now more particularly to FIG. 5, compartmentalized track 11 is shown in cross section attached to the mullion 10 as by means of screw 23. Cords 13--13 are shown in one section of the compartmentalized track 11 with hook 17 attached to bracket 24 which rides in the other channel of track 11, the two compartments of the tracks being separate by a common wall 26.
Referring now more particularly to FIG. 6, the manner in which applicant's invention is attached to the upper portion of the atrium or greenhouse wall is shown. Mullion 10 has bracket 25 attached thereto which in turn engages compartmentalized track 11, one channel of which houses cord 13--13. Bracket 25 is equipped with pulleys 18 and 19 over which cords 13--13 pass to a comparable fixture on the other side of the window in that portion of the atrium or greenhouse wall. The shade 12 is supported at its upper portion by rod 16 which in turn is connected to hook 17 attached to hook holder 27 which is in turn attached to bracket 25.
Referring now more particularly to FIG. 7, mullions 10--10 on either side of the atrium or greenhouse window are provided with compartmentalized tracks 11--11, one channel of which holds cords 13--13, in turn engaging pulleys 14--14 attached to the lower ends of compartmentalized tracks 11--11. Sliding in tracks 11--11 are carriers 28--28 in each track provided with combination handholds 29--29 which also engage hook 17 which in turn engages rod 16 attached to screen 12. Carriers 28--28 are provided with T-shaped fittings 30--30 extending at right angles therefrom to which cords 13--13 may be attached.
Referring now more particularly to FIGS. 8 and 9, it will be seen that member 15 slides in the two compartments of track 11 with the cords 13--13 passing through one compartment and through member 15 as shown in FIG. 9. In the position shown in FIG. 9, the member 15 may be raised or lowered if the device is uneven. The cord 13 in member 15 may also be tied off similar to the cord 22 in member 20, if desired.
In installing the unit, the unit is leveled and the endless portion of cords 13--13 is twisted and wrapped around the T-shaped fittings 30--30 as shown in the left hand portion of FIG. 7. The two open ends of cords 13--13 in the right hand portion of FIG. 7 are then twisted around the T-shaped fittings 30--30 and tied. In operation either of the handholds 29--29 on the left hand side or the right hand side may be raised or lowered and it will in turn cause the carriers 28--28 to be raised or lowered accordingly thus maintaining the shade in a level position even when going through the curved portion of an atrium or greenhouse wall.
Thus it will be seen that the invention discloses a manually operated device for raising or lowering shades on an atrium or greenhouse wall permitting the shade to be leveled as it is being raised or lowered, and also, in one version of the invention, permitting the shade to be raised or lowered using only one hand.
While this invention has been described in its preferred embodiment, it is to be appreciated that variations therefrom may be made without departing from the scope and spirit of the invention.
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A manually operated device for raising and lowering shades on glass-enclosed atrium or greenhouse walls which includes a self-leveling feature which corrects for uneven shade position and enables one to operate a shade on an atrium or greenhouse wall without the use of a motor-driven system.
Also disclosed is a manually operated device for raising and lowering shades on glass-enclosed atrium or greenhouse walls which may be raised or lowered with one hand grasping a handhold on either side of the shade, making it unnecessary to use both handholds.
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FIELD OF THE INVENTION
The invention relates generally to a method of producing hydrogen gas, and more particularly, to a method of producing hydrogen gas easily and safely “anywhere” “any time” by turning a metal highly reactive with water molecules into fine particles, and by utilizing mechano-corrosive reaction occurring in the surfaces of fine particles.
BACKGROUND OF THE INVENTION
In the research and development of a portable fuel cell, how to secure and supply hydrogen gas as fuel is an important technical problem to be solved. In connection with conventional methods of producing hydrogen gas, studies have been conducted on a method of decomposing water by use of photochemical reaction, a method of chemically converting city gas into hydrogen gas, a method of decomposing organic molecules with a strong acid, a method of synthesizing hydrogen gas by decomposing methanol together with water molecules through catalytic reaction, and so forth, and continual efforts have been made to put those methodes to commercial application. There are also automobile makers studying on a method of obtaining hydrogen by reforming gasoline.
However, the method of decomposing water by use of photo-chemical reaction has drawbacks in that it is not suited for application to a portable type producer of hydrogen gas because a large catalyst area for receiving light is required, and in addition, a production rate of hydrogen is low, necessitating storage of hydrogen for many hours. Further, the method of decomposing organic molecules with a strong acid has a drawback in that methoding of the acid is accompanied by hazards. Still further, the method of decomposing methanol together with water molecules by catalytic reaction has drawbacks in that, for example, high temperature not lower than 150° C. is required, a method of converting CO molecules obtained as by-product into CO 2 molecules before discharging is required, and a large quantity of water is required because methanol is diluted with water before use. Meanwhile, research and development have been conducted for long time on a method of causing hydrogen gas to be evolved by use of a metal alloy for hydrogen storage in place of the methodes of producing hydrogen gas, however, this method has not reached a stage of commercial application as yet, and has a drawback in that there is the need for applying heat at the time of hydrogen evolution. Thus, with the conventional methodes, it is in reality difficult to produce hydrogen gas serving as a satisfactory fuel for the portable fuel cell.
Under the circumstances, it is an object of the present invention to provide a method of producing hydrogen gas serving as fuel for a portable fuel cell, whereby hydrogen gas can be provided at room temperature easily, safely and inexpensively.
SUMMARY OF THE INVENTION
There has generally been known mechano-chemical reaction, which is a phenomenon wherein when a solid material is subjected to a mechanical action and effect, such as friction, fracture, and so forth, mechanical energy thereof is accumulated in the form of abnormality such as lattice defect, crack, strain, and compounds (impurities) inside the material, resulting in an increase in chemical reactivity of the surface of the material. Such a phenomenon as described belongs sometimes in a discipline called tribology. Upon friction between solid materials such as metals, and so forth, there occur not only generation of sound and heat but also various physical or chemical phenomena such as light emission, evolution of electrons and ions, formation of surface compounds, and so forth.
With the method of producing hydrogen gas according to the present invention, hydrogen gas is produced basically by utilizing mechano-chemical reaction. More specifically, an aluminum material or aluminum alloy material is turned into fine particles by applying friction movement to the surface of the material, in isolation from air, to thereby cause the mechano-chemical reaction to occur, whereupon there occurs an increase in reactivity (corrosion reaction) of the fine particles with water molecules in the surface of the material. Friction and fracture are generated in the course of turning the aluminum material or aluminum alloy material into the fine particles under water. While the fine particles each having a fresh and new surface of aluminum are constantly created due to friction, numerous cracks and lattice defects are developed in surface layers of the fine particles, thereby further enhancing reactivity thereof with water molecules. The water molecules seep into minute cracks formed in the aluminum material or aluminum alloy material, whereupon decomposition of water proceeds inside the minute cracks. Of the mechano-chemical reaction, a reaction whereby new compounds are formed due to reactions of the water molecules with the material is called a mechano-corrosive reaction. As a result of the mechano-corrosive reaction according to the present invention, there are generated Al(OH) 3 , Al 2 O 3 , and AlH 3 .
There are several solid materials having high reactivity with water, made of, for example, carbon, magnesium, iron, and so forth. Since these materials each normally have the surface covered with an oxide and so forth, the reactivity thereof with water is low. However, if a face (referred to as “newly generated face”) is created by removing or destroying the oxide and so forth, covering the surface of the respective materials, those materials intensely react with water. With the method according to the present invention, aluminum or aluminum alloy is used for a solid material. Since aluminum alloy is in wide-spread use as a building material and a constituent material for automobile engines, and so forth, refuse and cutting chips thereof is discharged in large quantity as industrial waste. The inventors intend to reduce the cost of production by making use of material categorized as industrial waste while contributing to solution of environmental conservation problems. Particularly, since aluminum cutting chips (curls) are a hard material made of an aluminum alloy containing silicon, copper, and so forth, in addition to working cracks already imparted thereto in the course of cutting work, the aluminum cutting chips are an inherently convenient material for use in preparation of fine particles.
It is known that aluminum and aluminum alloy cause the following chemical reactions with water molecules to occur, thereby forming hydrogen molecules:
Al+3H 2 O→Al(OH) 3 +(3/2)H 2 (1)
2Al(OH) 3 →Al 2 O 3 +3H 2 O (2)
These reactions are reactions occurring to the surface of aluminum or aluminum alloy, and in the case of the mechano-corrosive reaction associated with the method according to the present invention, additional reactions are anticipated to occur as follows:
3Al+3H 2 O→Al 2 O 3 +AlH 3 +(3/2)H 2 (3)
Al(OH) 3 +AlH 3 →Al 2 O 3 +3H 2 (4)
The reaction represented by reaction formula (3) is not a surface reaction but a bulk reaction occurring inside aluminum crystals, particularly, within cracks, and the same contributes to the mechano-corrosive reaction for production of massive hydrogen. Further, the reaction represented by reaction formula (4) is deemed to be an inter-facial reaction occurring in the boundary between the surface react and bulk reaction. The reaction formulas (3) and (4) represent a reaction mechanism for formation of hydrogen gas, featuring the method according to the present invention.
It has been found out as a result of studies carried out by the inventors that when friction, grinding and milling are applied to an aluminum alloy material, strain to the crystal lattice thereof and formation of microscopic cracks occur up to a depth about 30 μm from the surface thereof, so that friction energy is accumulated in a crystal surface layer to thereby cause the reactions as represented by the formulas (3) and (4), respectively, thus evolving massive hydrogen gas. The formation of the cracks and fracture inside the material is continued due to expansion in volume, attributable to reaction products formed by the mechano-corrosive reaction described as above, thereby causing self-propagation of the cracks, so that production of hydrogen gas is autonomously continued. When the fine particles generated by the friction, grinding and milling, applied to the aluminum or aluminum alloy material, are not more than about 50 μm in grain size, the reactions as represented by the formulas (3) and (4), respectively, proceed autonomously. In this case, it takes time of several days at room temperature to cause growth and accumulation of the cracks on a nanometer scale to occur inside the respective fine particles. In consequence, all the fine particles of aluminum collapse, so that there are formed fine particles of an aluminum oxide (alumina) as a final product in addition to hydrogen gas. Upon observation with a scanning electron microscope (SEM), it appears that a multitude of microscopic cracks run on the inside as well as the surface of the respective fine particles of alumina as formed, not more than about 50 μm in grain size, and the respective fine particles look like an aggregate of minute particles (about 10 μm in grain size).
Chemical reactions as represented by the formulas (1), (3), and (4), respectively, are expressed as a whole by the following chemical formula;
Al+(3/2)H 2 O→(1/2)Al 2 O 3 +(3/2)H 2 (5)
Accordingly, it is evident that by use of a raw material consisting of 1 mol (27 g) of an aluminum material and 1.5 mol (27 g) of water, it is possible to produce 0.5 mol (51 g) of an aluminum oxide (alumina) and 1.5 mol (3 g; 33.6 liter) of hydrogen gas.
A method of producing hydrogen gas according to claim 1 comprises the steps of causing friction and mechanical fracture accompanying the friction to occur to a metallic material under water, and increasing thereby chemical reactivity of atoms of the metallic material, in close proximity of the surface thereof; wherein water molecule are decomposed by accelerating corrosion reaction of water with the metallic material, thus producing hydrogen gas at room temperature.
According to claim 2 , in the method of producing hydrogen gas as claimed in claim 1 , formation of cracks and fracture inside the metallic material is continued due to expansion in volume, attributable to reaction products formed by the corrosive reaction to thereby cause self-propagation of the cracks to occur, causing evolution of hydrogen gas to autonomously continue.
According to claim 3 or 4 , in the method of producing hydrogen gas as claimed in claim 1 or 2 , the metallic material is preferably an aluminum or aluminum alloy material as industrial waste including refuse and cutting chips (curls) of an industrial aluminum material.
According to claim 5 or 8 , in the method of producing hydrogen gas as claimed in any one of claims 1 to 4 , the water is preferably pure water not substantially containing ionic impurities and organic molecules, and having an insulation resistance value not lower than 10 MΩ.
Thus, the present invention provides a method of producing hydrogen gas, suitable for use as fuel of a portable fuel cell, easily and safely at a relatively low cost. It is to be pointed out that the method according to the present invention excels other methods of producing hydrogen gas using methanol as raw material, presently under studies throughout the world, in that formation of hydrogen gas proceeds satisfactorily at room temperature, a reaction rate at high temperature (on the order of 60° C.) increases by about four times, massive hydrogen gas can be produced, by-products such as CO gas are not generated, and a production apparatus is simple and inexpensive. Furthermore, it is expected that the method according to the present invention is applicable to a large-scale hydrogen gas production system using, for example, surface waves of the sea.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a conceptual view of a hydrogen gas production apparatus used in demonstrating an embodiment of a method of producing hydrogen gas according to the present invention;
FIG. 2 is a schematic cross-sectional view of an apparatus for semi-automatically generating aluminum fine particles, developed by the inventor; and
FIG. 3 is a graph showing a hydrogen gas production capacity of the aluminum fine particles generated with the apparatus shown in FIG. 2 .
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Now, preferred embodiments of the present invention are described in detail hereinafter referring to the accompanying drawings. With an embodiment of a method of producing hydrogen gas according to the present invention, friction is produced on the surface of a solid material under water to the extent that strain up to a depth on the order of 0.1 μm from the surface is caused to occur to thereby cause minute cracks on the order of 30 μm to occur inside the solid material, so that friction energy is accumulated in surface layers of crystals, and reactions represented by the previously-described reaction formulas (3) and (4), respectively, occur, resulting in formation of a large quantity of hydrogen gas.
For the solid material, aluminum and aluminum alloy, having inherently strong reactivity against water molecules, are selected, and particularly, aluminum cutting chips (curls), which are industrial waste, are optimal for the purpose. Pure water not substantially containing ionic impurities and organic molecules is used for the water, and the pure water preferably has an insulation resistance value not lower than 10 MΩ.
Next, an example of a hydrogen gas production apparatus used in demonstrating the embodiment of the method of producing hydrogen gas according to the present invention will be explained referring to FIG. 1 . In FIG. 1 , the hydrogen gas production apparatus generally indicated by reference numeral 10 comprises a reaction chamber 12 made of a synthetic resin material excellent in water resistance. The reaction chamber 12 is filled up with the pure water. The hydrogen gas production apparatus 10 also comprises a pure water feeding means 14 for feeding pure water to the reaction chamber 12 . The reaction chamber 12 is provided with an observation window 12 a for observing the interior of the reaction chamber 12 .
A grinding plate 16 made of a ceramic material is provided inside the reaction chamber 12 . The grinding plate 16 is rotated by an electric motor 18 . Reference numeral 20 denotes a reduction gear. Inside the reaction chamber 12 , a solid material 22 is fixedly held by a solid material holder 24 , and is pressed toward the grinding plate 16 by a compression spring 26 .
The hydrogen gas production apparatus 10 further comprises a hydrogen gas recovery vessel 28 for recovering hydrogen gas as produced and a sampling vessel 30 .
Production of hydrogen gas was carried out as follows: For the solid material 22 , aluminum and aluminum—silicon alloy were used. Hydrogen as produced was analyzed by the gas chromatography, and fine particles of the solid material, generated by abrasion, were observed with an optical microscope, and a scanning electron microscope (SEM). Further, the composition of the fine particles as generated was analyzed by the Auger electron spectroscopy (AES) and EPMA.
It was observed that hydrogen started to be evolved in the hydrogen gas production apparatus 10 by the agency of aluminum upon the start of friction movement, and was turned into bubbles to be accumulated in the upper part of the hydrogen gas production apparatus 10 . It was observed even by the naked eye that hydrogen gas burst forth, particularly, from between the grinding plate and friction faces of an aluminum material, thus having directly proven that the method according to the present invention is based on the mechano-chemical reaction. A quantity of hydrogen gas generated by the hydrogen gas production apparatus 10 was found to be in a range of about 300 to 600 cc per 1 g of aluminum. The quantity represents about half of a quantity of hydrogen gas generated as anticipated from the previously described chemical formula (5). It is deemed that this is because aluminum fine particles generated due to abrasion were diverse in grain size, and parts of the aluminum fine particles remained in the form of aluminum hydroxide [(the reaction formula (1)] since hydrogen-forming reaction at room temperature was imperfect. It was further observed that when temperature in the reaction chamber was increased to a range of 60 to 80° C., a reaction rate was increased by several times, thereby turning all the aluminum fine particles into alumina.
As a result of observation with the microscope, it was found that as for larger aluminum particles on the order of 100 μm in grain size, only the surface thereof contributed to evolution of hydrogen gas while the interior part thereof remained in the form of aluminum metal. Hydrogen gas as formed was found having a purity on the order of 98%, containing nitrogen and oxygen as impurities, which are presumed to come mainly from air dissolved in the pure water. Upon use of city water in place of the pure water, evolution of hydrogen gas by the agency of aluminum substantially stopped. It is clear from this that use of pure water is important. It was further observed that when hydrogen-forming reaction was caused to occur after mixing about 1% of a common organic substance, such as methyl alcohol or acetone, in pure water, a production quantity of hydrogen decreased down to several % of that as compared with the case of using the pure water.
Aluminum pulverized under water continued to evolve hydrogen gas for many hours. Aluminum fine particles not more than 50 μm in grain size, formed due to friction, were oxidized until even the interior part thereof was turned into white alumina, continuing to evolve hydrogen gas. In the case of particles larger in grain size, corrosion reaction occurred only to the surfaces thereof, causing hydrogen gas to be evolved, while the interior part thereof remained in the form of aluminum.
In order to incorporate the method of producing hydrogen gas according to the present invention into a potable fuel cell system, there is the need for producing a large amount of aluminum alloy fine particles. FIG. 2 is a schematic cross-sectional view of an apparatus for semi-automatically generating aluminum fine particles, developed by the inventors. The apparatus for semi-automatically generating the aluminum fine particles comprises a rotating grinder which is driven in rotation by a motor through the intermediary of a gear box, and a stationary grinder provided on the underside of the rotating grinder. The stationary grinder and rotating grinder are made of granite, respectively. An interface between the rotating grinder and stationary grinder serves as a grinding face, and the grinding face is so positioned as to be always under water. With the apparatus for generating the aluminum fine particles, aluminum cutting chips (curls) is used as aluminum alloy material to be pulverized. The aluminum cutting chips along with water are fed to the grinding face through an opening provided in the rotating grinder. Fine particles generated with the apparatus are in a range of 10 to 200 μm in grain size, and a larger particle portion of the fine particles is fed again to the grinding face to be further pulverized. Upon observation of the fine particles thus generated with the SEM, the fine particles were found to be particles in indefinite shape, having a multitude of cracks running in the surfaces thereof.
When generating the fine particles by use of the apparatus for semi-automatically generating the aluminum fine particles, evolution of hydrogen gas is observed, and the hydrogen gas is discharged into air. Several grams of the fine particles as generated with the apparatus were collected to examine a hydrogen gas production capacity thereof. FIG. 3 is a graph showing the results of such examination. It is shown that micro-cracks were formed in the fine particles when the fine particles were generated. Following an activation treatment whereby impacts such as temperature, ultrasonic waves, etc. were applied to the fine particles, heat treatment (annealing) at room temperature for several days was applied thereto, whereupon growth of the micro-cracks occurred to be followed by growth of more minute nano-cracks throughout the fine particles. At this point in time, the fine particles were placed under a condition of room temperature (20° C.). Thereafter, the fine particles were cooled to 5° C. and kept in this condition. Subsequently, the fine particles were placed again under the condition at 20° C., whereupon a hydrogen gas production quantity abruptly increased.
While there has been described the preferred form of the present invention, it is to be understood that the scope of the invention is not limited thereto, and many modifications and variations may be made without departing from the spirit or scope of the following claims. Obviously those modifications and variations are to be included in the scope of the invention.
For example, referring to the embodiment described in the foregoing, there have been shown the hydrogen gas production apparatus and the apparatus for generating the aluminum fine particles, used in carrying out the embodiment of the method of producing hydrogen gas according to the present invention. However, it is to be understood that those apparatus are shown only by way of example for use in carrying out the present invention.
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There is provided a method of producing hydrogen gas serving as fuel for a portable fuel cell, whereby hydrogen gas can be provided easily, safely, and at a low cost. To that end, the method of producing hydrogen gas comprises the steps of causing friction and mechanical fracture accompanying the friction to occur to a metallic material under water and increasing thereby chemical reactivity of atoms of the metallic material, in close proximity of the surface thereof; wherein water molecules are decomposed by accelerating corrosion reaction of water with the metallic material. Further, for the metallic material, an aluminum or aluminum alloy material is used as industrial waste including refuse and cutting chips (curls) of an industrial aluminum material. Meanwhile, pure water not substantially containing ionic impurities and organic molecules is used for the water.
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BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to ground anchors, and more specifically to driven pivoting ground anchors.
[0003] 2. General Background
[0004] Ground anchors, or earth anchors, of the driven and pivoting or tilting type are well known and generally include a main body portion having a leading edge adapted to be driven into the ground, a trailing edge including an outturned lip and a cable or rod or guide wire attachment point intermediate the leading and trailing edges generally positioned from about the midpoint of the overall length of the anchor or towards the trailing edge so that upon exertion of the force on the cable or attached rod or guide wire, after insertion of the anchor into the ground, the trailing edge's outturned lip will bite into the earth, causing the anchor to rotate or pivot to a locked position generally at a right angle to the withdrawal force.
[0005] Widely currently used driven pivoting anchors of the type described are available from the assignee of this application under its Duckbill trademark and generally employ a somewhat cylindrical main body portion having an attachment point intermediate its ends and having at its forward end a plurality of forwardly extending guiding plane surfaces which terminate in chiseled edges. The cylindrical body shaped member, at its trailing end, has a bore extending into the body of the cylindrical member for receipt of a drive rod for driving the anchor into the earth and is provided with an outturned lip on a side of the cylindrical body portion opposite the side having the cable or guide wire attachment point.
[0006] Such anchors are shown, for example, in U.S. Pat. Nos. 4,044,513 and 4,096,673, both of which are assigned to the assignee of this application. Improvements of such anchors are well
[0007] Such anchors are shown, for example, in U.S. Pat. Nos. 4,044,513 and 4,096,673, both of which are assigned to the assignee of this application. Improvements of such anchors are well known and include, for example, applicant's pending Design application Ser. No. 29/270,187 and U.S. Utility application Ser. No. 11/803,138 filed May 14, 2007.
[0008] Other variants of such anchors are sold, for example, by Foresight Products, LLC under trademarks Manta Ray and Stingray and employ extensive side projecting wings that extend backwardly and outwardly from the leading edges to a greater or lesser degree and provide greater resistance to withdrawal of the anchor after the anchor has been driven into the ground and rotated to the point where the wings lie substantially normal to the tension direction of the cable.
[0009] While such anchors, both of the wingless, small-winged and large wing design, have found successful utility in many applications, including use in connection with revetment and soil retaining mats. However, the chiseled or sharpened leading edges which facilitate penetration into the ground can, in certain instances, cause damage to certain types of soil retaining mats which are commonly used in turf reinforcement and ground stabilization. Such mats, often known as High Performance Turf Reinforcement Mat (HPTRM) of the type available under the mark Pyramat from Propex, Inc. or of the type shown, for example, in U.S. Pat. No. 5,616,399 entitled “Geotextile Fabric Woven or a Honeycomb Weave Pattern and having a Cuspated Profile after Heating,” may consist of individual strands essentially woven together and formed or fused to provide the mat. The strands are generally manufactured of plastics material. Other fabric-like woven mats utilizing similar or different materials are also known, as are non-woven mats. Where it is desired to anchor such mats to the underlying soil, the use of the previously known driven pivoting anchors can cause damage to the mat, particularly since the chiseled or sharpened leading edges will have a tendency to cut through the material of the mat, thereby weakening the mat.
[0010] It would therefore be an advance in the anchoring field to provide an anchor suitable for use with such turf reinforcement mats which could be driven through the mat with a reduced likelihood of damage to the mat.
SUMMARY OF THE INVENTION
[0011] The above advances are provided by the current invention by utilizing a driven pivotal anchor where the leading end is provided with a curved or rounded non-sharp leading end and flattened guiding plane edges.
[0012] In an embodiment of the invention a plurality of ribs or guiding plane leading edges extend forwardly of the generally cylindrical main body portion of the anchor with each edge being either blunt or rounded and with each edge converging to a common leading end which is generally rounded.
[0013] In an embodiment of the invention the leading edges projecting forward of the generally radial cylindrical main body portion are circumferentially spaced from one another and formed as the outside surface of ribs or guiding planes with the edges formed blunted or rounded and which converge to a common leading front end, the leading front end being rounded. In an embodiment of the invention the generally cylindrical body member has four leading edges formed as orthogonal ribs or planes extending forwardly of the generally cylindrical body portion and tapering to a common leading end which is rounded generally in a partial spherical configuration.
[0014] It is therefore an object of the invention to provide a ground anchor having improved utility for use with mat structures having leading edge surfaces having a reduced tendency to damage the mat during driving of the anchor through the mat structure.
[0015] It is a further and more specific object of this invention to provide a driven pivoting anchor having a rounded or ball-like leading end.
[0016] These and other objects will be apparent to those of ordinary skill in the art from a description of the illustrated preferred embodiment, being understood that this is only one such embodiment of this invention and that many variations of shape and dimension are within the scope of this invention. Specifically the generally overall shape of the anchor, the shape of the main central body portion, the shape and extent of the side wings and the number of leading edges or ribs are all modifiable as is generally known to those of ordinary skill in the art and practice in differing commercially available embodiments of driven pivoting anchors.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a perspective view of the anchor of this invention.
[0018] FIG. 2 is a cross sectional view of the anchor of this invention taken along the lines 2 - 2 of FIG. 1 .
[0019] FIG. 3 is a cross sectional view of the anchor taken along the lines 3 - 3 of FIG. 1 .
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0020] FIG. 1 illustrates a ground or earth anchor 10 of the type often referred to as a driven and rotating or pivoting anchor in that the anchor is driven into the ground by force and after having being driven to the desired depth, a cable or rod attachment member attached to the anchor is pulled in a direction to withdrawal the anchor from the ground. Because of the design of the anchor and the position of the attachment of the cable or pulling rod to the anchor, the pulling of the anchor by the attachment member causes the anchor to undergo a pivoting or rotation in the ground towards a final position in which the longitudinal axis of the anchor is positioned more towards a position normal to the pulling cable or rod.
[0021] Such anchors often include a main body section 11 , which may be generally cylindrically formed (other shapes are known in the art, including rectangular and oval), a leading edge 12 , a trailing edge 13 , a raised section 14 having means 2 for attachment of a cable, shackle, pivot bolt or the like, which may comprise or be attached to the withdrawing force member which causes the anchor to rotate or pivot from its driven position to its final locked position. As shown in FIG. 1 , oftentimes the attachment means 2 is merely an opening through a raised rib 16 on one side of the main body portion 11 . The opening may receive a looped crimped cable end or a shackle bracket or the like. Alternative structures are well known such as where the rib-like structure includes attachment means for receipt of the end of a T-shaped rod or other type of swiveling device. An open bore 17 in the trailing edge extends into the main body portion 11 terminating in a blind end 18 which may, as shown in FIGS. 2 and 3 , be flat or which may be rounded or otherwise configured. A driving rod extends into the bore 17 and is used to drive the anchor into the earth. The driving rod may simply be impacted by a hammer for smaller anchors or may be driven by a pneumatic or hydraulic reciprocating power driver for larger anchors.
[0022] In the embodiment illustrated the main body portion is generally cylindrical and terminates at a leading end 11 a of the main body portion in a frustoconical section 11 b and four equally-distanced spaced ribs of which three, 15 , 17 , and 19 can be seen in FIG. 1 , the fourth being on the bottom opposite the rib 19 . Each of the ribs has an outer edge surface 18 and the rib surfaces 18 converge towards the leading end 12 . The outer edges 18 may be flat or blunt as shown in FIG. 1 or may be outwardly curved but preferably are not provided with a sharp edge. The ribs 15 , 16 , 17 may have different shapes. The ribs 15 and 17 extending back behind the frustoconical portion 11 b and converge into side wings 20 and 21 , which also preferably have rounded or non-sharp outer edges 22 . The rib 19 has its edge 18 extending back to the leading end of the generally conical section 11 a and blending into the top edge surface 14 of the raised rib 16 .
[0023] The four ribs, in this embodiment, converge together to a rounded nose 25 at the end 12 . Although different shapes can be provided for the nose, a part spherical or partial ball shape is preferred, although a parabolic shape or some other curvature is acceptable, it being important that the leading end 12 not be provided with a sharp edge. By providing a rounded leading edge 12 , the anchor is able to be driven through the mat with minimal damage to the stranding of the mat and, in fact, for smaller anchors without severing any of the strands of the mat as the ball-like nose 25 pushes its way between the strands and non-sharp, rounded or blunt edges 18 force the strands apart as the main body portion of the anchor begins to pierce through the mat.
[0024] The side 31 of the anchor opposite the raised rib 16 is provided at its trailing edge 32 with an outturned lip 33 to facilitate pivoting during drawback, as is well known in the art.
[0025] In use the mat schematically shown at 60 is placed in position on the surface to be retained or secured and the ball-like nose of the anchor is placed against the mat surface and is then begun to be driven through the mat. As the ball-like nose, or rounded nose, enters the structure of the mat it will cause the strands of the mat to be pushed aside. As the anchor is driven further into the mat, the degree by which the strands are pushed aside will increase to allow the anchor to pass through the mat. In many instances utilizing normally stranded mats and standard smaller sized anchors equipped with the rounded or ball-like nose leading edge, the entire anchor can be pushed through the mat without breaking the strands of the mat. In other instances when slightly larger anchors are used one or more of the strands may be stretched beyond its limit and separate, but damage to the mat is minimal compared to the use of sharper or chiseled or leading edges or sharper edges extending backwardly from a leading point. While the use of blunted, rounded non-sharpened nose portions and leading side edges on the ribs and along the body may increase the resistance to driving of the anchor into the ground, when such anchors are used for soil erosion or soil stabilization, they are most often used in connection with looser or less resistant soil conditions such that the disadvantage, which may rise from an increase in resistance to driving in comparison to chiseled edged or sharpened edged anchors is minimized.
[0026] It will therefore be understood from the above that this invention improve upon the prior art driven pivoting anchors by providing an intentionally rounded non-sharp leading nose or leading end which can be pushed through a woven or non-woven retaining mat with minimal damage to the mat.
[0027] Persons of ordinary skill in the art will understand that this invention may be practiced in embodiments other than that illustrated. It is not intended that this invention be limited to the particular anchor shape shown.
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An earth anchor of the pivoting type having an essentially cylindrical body, a blind bore extending thereinto from a trailing axial end of the cylindrical body and a leading edge projecting from a leading end of the body, the leading edge being formed as a rounded surface adapted for penetration through reinforcement paths while minimizing severing of the strands of the mat.
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CROSS REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims priority from U.S. Provisional Application No. 60/387,207, filed Jun. 7, 2002, which is incorporated by reference as if fully set forth.
FIELD OF INVENTION
[0002] The present invention generally relates to communication systems. More specifically, the invention relates to communication systems using multiple access air interfaces and direct conversion/modulation for multi-carrier processing.
BACKGROUND
[0003] A digital communication system typically transmits information or data using a continuous frequency carrier with modulation techniques that vary its amplitude, frequency or phase. After modulation, the signal is transmitted over a communication medium. The communication medium may be guided or unguided, comprising copper, optical fiber or air and is commonly referred to as the physical communication channel.
[0004] The information to be transmitted is input in the form of a bitstream which is mapped onto a predetermined constellation of symbols that defines the modulation scheme. The mapping of each bit as symbols is referred to as modulation.
[0005] A prior art base station is typically required to utilize multiple carriers converging continuous frequency spectrum. A block diagram of prior art superheterodyne receiver 11 which may be implemented in the base station is shown in FIG. 1. An operator is typically assigned two (2) or more channels Ch 1 -Ch 4 (carriers), and desires to use them in each cell (frequency reuse=1). If this is not possible due to certain constraints which result in a frequency re-use factor that is lower, the operator has a finite number of channels, and will partition them in contiguous sections of spectrum so that a number of adjacent channels are used in each cell. In this case, the receiver 11 is required to process all channels (carriers) simultaneously. This minimizes hardware cost, size, and power consumption.
[0006] In the past, the high demanding requirements of base station receivers could only be met with a superhetrodyne architecture. The direct conversion architecture has many inherent problems that result from downconverting the RF signal directly to baseband. These problems include self-mixing which creates DC offsets in the baseband signal; even-order distortion which converts strong interfering signals to baseband; 1/f noise which is inherent in all semiconductor devices and which is inversely proportioned to the frequency (f) and which masks the baseband signal; and spurious emissions of the LO signal which interferes with other users. Direct conversion receivers also stress the state-of-the-art capabilities of the analog baseband processing components because gain control and filtering must all be done at baseband. This requires expensive amplifiers that possess high dynamic range and a wide bandwidth.
[0007] Conventional multi-carrier radios are based on a superheterodyne radio architecture that utilizes an intermediate frequency (IF) and direct digital sampling to block convert multiple carriers to and from baseband, as shown in FIG. 1 for the receiver. Because the IF is typically located above 50 MHz, direct digital sampling requires expensive high-speed or sub-sampling data converters, such as analog-to-digital converters (ADC) and digital-to-analog converters (DACs) capable of sampling rates greater than 100 MHz and requiring very low clock jitter.
[0008] Another disadvantage to direct digital sampling is the IF Surface Acoustic Wave (SAW) filters needed to reject interference in adjacent channels. The maximum number of carriers supported by the radio determines the bandwidth of the SAW filter. Support for a different number of carriers requires additional SAW filters. As an alternative, one IF filter can be used that covers the entire band of interest, but then additional dynamic range is needed in the ADC to handle the additional interference.
[0009] This can be understood from the dynamic range of the received signal. When the uplink channels are all under the control of the same base station, the radio frequency (RF) carriers will be received at similar power levels, requiring relatively less dynamic range in the ADC. However, if the IF filter bandwidth covers the entire band, uplink channels belonging to other base stations will be present at the input to the ADC. These channels can be at a very high level, thus requiring more dynamic range in the ADC.
[0010] Referring back to FIG. 1, the receiver 11 is used for digital multi-carrier wireless communication, for example a Code Division Multiple Access (CDMA) communication. As a signal is received at the antenna 15 , it passes a first bandpass filter 16 and a linear amplifier 17 . A second bandpass filter 18 receives the signal from the amplifier 17 and provides the signal to a mixer 19 . A local oscillator 20 is connected to the mixer 19 and the mixer 19 translates the signal from RF to IF and is then filtered by a bandpass filter 21 .
[0011] The bandpass filter 21 is connected to an ADC 22 which provides its digitized output to a digital downconverter 23 . A complex numerically-controlled oscillator 24 is used to control the digital downconverter 23 to translate each channel at IF to baseband. The digital downconverter 23 provides quadrature baseband signals to a bank of finite impulse response (FIR) filters 25 , which perform pulse shaping and interference rejection. The outputs from the FIR filters 25 are provided to respective digital automatic gain control circuits (DAGCs) 35 which provide outputs in four (4) respective channels 45 . The digital data from each channel is sent to a digital processor (not shown) for further processing, such as data demodulation and decoding. Although four (4) channels are shown as an example, those of skill in the art would realize that there could be any number of channels.
[0012] A similar process is used on the transmission side, as shown in FIG. 2, which is a block diagram showing prior art transmitter 51 using four (4) input channels Ch 1 -Ch 4 65 . The four (4) input channels 65 are provided to respective power control circuits 75 which, in turn, provide their outputs to respective FIR filters 85 . The FIR filters 85 are typically used for pulse shaping purposes. The outputs from the FIR filters 85 are provided in quadrature to a digital up converter 95 , which is connected to a complex numerically-controlled oscillator 96 . The output of the digital up converter 95 is provided to a digital-to- analog (DAC) circuit 97 , which supplies its analog output to a first bandpass filter 98 , which in turn is provided to an IF mixer 99 . The IF mixer 99 receives its local oscillator signal from an oscillator 100 and provides an output to a second bandpass filter 102 . The output bandpass filter is amplified at an amplifier 103 , filtered at an output bandpass filter 104 and provided for transmission via antenna 105 .
[0013] In these configurations (FIGS. 1 and 2), various conversions are performed with RF components. The manufacturing costs of these RF components is significant. Therefore, it would be advantageous to provide a circuit which avoids multiple RF conversions to the maximum extent practical. Additionally, a direct conversion design for a receiver and transmitter are desired.
[0014] The major problem with prior art direct conversion receivers is the generation of DC offsets at the output of the receiver. The major sources of DC offset are local oscillator self-mixing and second order intermodulation (IP 2 ) of the mixer. DC offsets may be quite large, leading to saturation in the ADC and other performance problems in the receiver.
[0015] Solutions to the direct conversion problems have been understood for some time, but they were not practical or cost effective until recent technology developments made possible integrated solutions on monolithic RF integrated circuits (RFICs). These solutions to the problems include balanced (differential) structures that eliminate even-order distortion, SiGe semiconductor technology which exhibits low 1/f noise and excellent linearity, and harmonic mixing that eliminates self-mixing and LO spurious emissions. The move to wideband wireless technologies has also reduced the contribution of the 1/f noise to the overall noise floor of the direct conversion receiver. In addition, high-speed, high linearity amplifiers are now available to meet the analog baseband processing requirements.
[0016] However, there are still major problems with direct conversion receivers in the generation of DC offsets at the output of the receiver. The major sources of DC offset are LO self-mixing and second order intermodulation of the mixer. DC offsets may be quite large leading to saturation of the ADC and other performance problems in the receiver. Accordingly, although there have been advances with the prior art, these prior art techniques these still fall far short of the optimum performance.
SUMMARY
[0017] The present invention is a radio communication device, such as a receiver, transmitter or transceiver, that includes a direct conversion, multi-carrier processor. The multi-carrier processor frequency translates RF channels to and from baseband using a quadrative modulator (transmitter) or demodulator (receiver). Because the analog signals are translated close to DC, conventional adjustable filters may be programmed via a bandwith control unit to support different number of channels (carriers) and channel bandwidths.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] [0018]FIG. 1 is a block diagram of a prior art superhetrodyne with direct digital sampling multi-carrier receiver.
[0019] [0019]FIG. 2 is a block diagram of a prior art superhetrodyne with direct digital transmitter.
[0020] [0020]FIG. 3 is a block diagram of a direct conversion multi-carrier receiver made in accordance with the present invention.
[0021] [0021]FIG. 4 is a block diagram of a direct conversion multi-carrier transmitter made in accordance with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] The present invention will be described with reference to the figures where like numerals represent like elements throughout.
[0023] This present invention enables block processing of multiple RF carriers in a wireless communication system using a direct conversion transmitter/receiver and baseband signal processing. Such a multi-carrier radio reduces cost by simultaneously processing multiple carriers within a single radio, rather than processing each carrier in separate radios.
[0024] [0024]FIG. 3 is a block diagram showing an exemplary embodiment of a communication receiver 130 constructed in accordance with the invention. The receiver 130 receives a plurality of communication signals Ch 1 , Ch 2 . . . Ch n , each of which is sent over a carrier frequency F 1 , F 2 . . . F n , respectively. These signals will be referred to collectively hereinafter as multi-carrier signal S 1 .
[0025] The receiver 130 has an antenna 131 , a first bandpass filter 132 , a radio frequency amplifier 133 and a second bandpass filter 134 . Also included are first and second mixers 141 , 142 , connected to a local oscillator 143 , first and second low pass filters (LPFs) 145 , 146 , a bandwidth control circuit 147 and first and second baseband amplifiers 151 , 152 . The first and second mixers 141 , 142 coupled with the local oscillator 143 comprise a demodulator 144 .
[0026] A first automatic gain control (AGC) circuit 153 is connected to the baseband amplifiers 151 , 152 , and the outputs from the baseband amplifiers 151 , 152 are provided to ADC circuits 161 , 162 . The digitized outputs from the ADCs 161 , 162 are provided to a second AGC circuit 163 . The second AGC circuit 163 provides an AGC output to a DAC 164 , which in turn provides an input to the first AGC circuit 153 , thereby controlling the gain of baseband amplifiers 151 , 152 .
[0027] The output from the second AGC circuit 163 is provided to a digital downconverter 171 , which provides separate outputs to a plurality FIR filters 181 - 185 , and in turn to a plurality DAGCs 191 - 195 to provide outputs to a plurality of channels Ch 1 -Ch n 198 - 202 . The use of the digital-analog AGC loop 163 , 164 , 153 reduces the dynamic range at the output and therefore reduces the requisite dynamic range of digital AGC circuits 191 - 194 downstream.
[0028] The antenna 131 captures the multi-carrier signal S 1 and inputs the signal S 1 to bandpass filter 132 , which provides band filtering to reject out-of-band interference. After filtering, the signal is input to the low noise amplifier (LNA) 133 which sets the noise floor of the receiver 130 . The output of the LNA 133 is filtered through bandpass filter (BPF) 134 to filter any intermodulation distortion produced by the LNA 133 .
[0029] The output of the LNA 133 is sent to the demodulator 144 , which consists of mixers 141 and 143 and the stable local oscillator (LO) 143 . The LO 143 has two outputs, one in-phase (I) and one in quadrature (Q), relative to the carrier. The frequency of the LO 143 is the center frequency of the input channels Ch 1 -Ch n , (F 1 - F n )/2; where F 1 is the carrier frequency of the first channel Ch 1 and F n is the carrier frequency of the nth channel Ch n . The demodulator 144 translates the desired signal from RF to baseband, centering the signal around DC.
[0030] The I and Q signals are sent to LPFs 145 and 146 , which provide interference rejection in order to minimize the dynamic range of the downstream baseband processing elements 151 - 194 . Since the analog signals are translated close to DC, conventional adjustable filters 145 and 146 may be programmed via bandwith control 147 to support different number of channels and channel bandwidths.
[0031] ADCs 161 , 162 are pair of conventional low cost ADCs which digitize the I/Q signals from the demodulator 144 . The individual channels Ch 1 -Ch n are down-converted to baseband by the DDC 171 .
[0032] Channel filtering and pulse shaping is applied to each channel Ch 1 -Ch n by the FIR filters 181 - 185 .
[0033] The AGC process is performed in two steps. The first step is performed in the first and second AGC circuits 151 , 163 to adjust the gain of the baseband amplifiers 151 , 152 to maintain the signal within the dynamic range of the ADCs 161 , 162 . The second step of the AGC process is performed digitally in the DAGC block 191 - 195 and is used to reduce the bitwidth of the I/Q signals to the minimum required for each channel 198 - 202 .
[0034] As shown in FIG. 3, the receiver 130 operates as a multi-carrier direct conversion receiver. The frequency block containing the multiple RF channels is thereby down-converted directly to baseband as a block of frequencies.
[0035] [0035]FIG. 4 is a block diagram showing an exemplary embodiment of a direct conversion communication transmitter 230 constructed in accordance with the invention. The individual channels (Ch 1 -Ch n ) 231 - 234 are first sent through FIR filters 241 - 244 and are digitally upconverted by a digital upconverter DUC 247 . This provides a digital baseband signal, which is used to drive a pair of low cost DACs 251 , 252 . The DUC 247 converts an input signal into I/Q signal components by shifting the center frequency from zero to +/− one half of the bandwidth.
[0036] The output of the DUC 247 , comprises two digital outputs which are separated in quadrature. These I/Q outputs are input to the DACs 251 and 252 , which convert the digital signals to analog. The analog outputs from DACs 251 , 252 are provided to LPFs 253 , 254 , the bandwidth of which are controlled by bandwidth control circuit 255 . The LPFs 253 , 254 filter the analog signals and provide their respective filtered outputs to a modulator 260 , comprising two mixers 261 , 262 , the LO 263 and the summer 264 . The mixers 261 , 262 are controlled by the LO 263 and provide mixed outputs to the summer 264 . The modulator 260 provides an output to the bandpass filter 265 and, in turn, to a first RF amplifier 266 . The RF amplifier 266 is controlled by gain control circuit 267 and provides an output to bandpass filter 268 and RF power amplifier 269 which amplifies the signal for transmission, via antenna 270 .
[0037] As can be clearly seen in FIGS. 3 and 4, the direct conversion multi-carrier processor in accordance with the present invention avoids the disadvantages of the superheterodyne radio by eliminating the IF stage. This reduces cost in the radio and allows the data converters to operate at baseband at a lower clock rate, which further reduces cost. Adjustable bandwidth filters are readily realizable at baseband, allowing flexible support for variable carrier spacing and the number of carriers to be processed in the radio. This also reduces the dynamic range required in the ADC because only the desired carriers are present at the ADC, again reducing cost.
[0038] The present invention is applicable to wireless communication systems, including wireless local loop, wireless LAN applications, and cellular systems such as WCDMA (both UTRATDD and UTRAFDD), TDSCDMA, CDMA2000, 3xRT, and OFDMA systems.
[0039] While the present invention has been described in terms of the preferred embodiment, other variations, which are within the scope of the invention as outlined in the claims below will be apparent to those skilled in the art.
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A radio communications device such as a receiver, transmitter or transceiver provides direct conversion of quadrature signals between a radio frequency signal and a plurality of resolved channels. The device provides block processing of multiple RF carriers in a wireless communication system using a direct conversion transmitter/receiver and baseband signal processing.
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BACKGROUND OF THE DISCLOSURE
1. Field of Invention
The present invention relates generally to chemical mechanical polishing, and more specifically, to the use of utility wafers for simulating chemical mechanical polishing processes.
2. Background of Invention
In semiconductor wafer processing, the use of chemical mechanical planarization, or CMP, has gained favor due to the enhanced ability to stack multiple devices on a semiconductor workpiece, or substrate, such as a wafer. As the demand for planarization of layers formed on wafers in semiconductor fabrication increases, the requirement for greater system (i.e., process tool) throughput with less wafer damage and enhanced wafer planarization has also increased.
Two exemplary CMP systems that address these issues are described in U.S. Pat. No. 5,804,507, issued Sep. 8, 1998, to Perlov et al., and in U.S. Pat. No. 5,738,574, issued Apr. 15, 1998, to Tolles et al., both of which are hereby incorporated by reference. Perlov et al. and Tolles et al. disclose a CMP system having a planarization apparatus that is supplied wafers from cassettes located in an adjacent liquid filled bath. A transfer mechanism, or robot, facilitates the transfer of the wafers from the bath to a transfer station. The transfer station generally contains a load cup that positions the wafer into one of four processing heads mounted to a carousel. The carousel moves each processing head sequentially over the load cup to receive a wafer. As the processing heads fill, the carousel moves the processing head and wafer through the planarization stations for polishing. The wafers are planarized by moving the wafer relative to a polishing pad in the presence of a slurry or other polishing fluid medium.
The polishing pad may include an abrasive surface. Additionally, the slurry may contain both chemicals and abrasives that aid in the removal of material from the wafer. After completion of the planarization process, the wafer is returned back through the transfer station to the proper cassette located in the bath.
The ideal substrate polishing process can be described by Preston's equation: R = K P P Δ s Δ t
where:
R is the removal rate;
K p is the Preston coefficient;
P is the applied pressure between the workpiece and the abrasive pad; and
Δs/Δt is the linear velocity of the abrasive pad relative the workpiece.
Preston's equation has shown to be a reasonably accurate model for the planarization of silicon dioxide, copper and tungsten, although the dependence of K p on process variables, such as slurry composition and pad properties, is not well understood. For example, the theoretical value of the Preston coefficient Kp=1/2E (where E is Young's modulus of the surface being polished) does not explain the polishing rate variation with other important process variables such as pad type, pad condition, slurry abrasive and slurry chemicals. Illustrative of this is that the polishing rate has been known to vary as much as 20 percent between pads having different hardness. As a result, most chemical mechanical polishing process modeling is performed using empirical data.
To better predict the results of an actual chemical mechanical polishing process, typically a simulation of the processes is performed using utility wafers in the place of production wafers. Generally, the simulation comprises running a number of utility wafers through the chemical mechanical polishing system, while periodically inserting and polishing a test wafer from which the polishing attributes can be obtained to construct a model of the polishing process. For example, in an exemplary CMP simulation, approximately 2000 polishing cycles are run. After every 100 utility wafers that are polished, a test wafer is polished, removed and measured to obtain data indicative the process. Once approximately 2,000 polishing cycles are completed, a data base representative of the process can be constructed. Other simulations may be configured to run more or less polishing cycles, and may polish test wafers at different frequencies.
The utility wafers typically used to simulate the polishing of the production wafers generally are silicon wafers covered with a thin layer of oxide. Generally, the oxide layer can only withstand one to two polishing cycles through the chemical mechanical polishing system. The utility wafer, once the oxide has been substantially removed by polishing, can be reused after being stripped of the remaining oxide coating and a new layer of oxide is redeposited thereon. As the cost of depositing an oxide layer is not nominal, simulation tests that use between 1,500-2,000 utility wafers can become quite costly.
One solution to the high cost of the oxide coated silicon wafers is described in U.S. Pat. No. 5,890,951, issued Apr. 6, 1999, to Cuong van Vu. Cuong van Vu teaches a utility wafer used for mechanically conditioning and stabilizing a polishing pad. This utility wafer is comprised of a high purity solid ceramic or metal member that has a thickness of between about 3-150 mils. The thickness of the Cuong van Vu utility wafer provides some resistance to breaking when the wafer is exposed to the forces applied in a chemical mechanical planarization process. For example, Cuong van Vu teaches a quartz wafer thickness of 50 mils, and a silicon/quartz composite wafer that can withstand the surface tension forces experienced during the removal of the polished wafer from the polishing pad (dechucking) without breaking or cracking the wafer.
However, ceramic wafers of this type are prone to chipping as the edge of the wafer contacts the retaining ring of the polishing head during the planarization process, during dechucking from the polishing pad, or during handling in general. As the wafer contacts the retaining ring, pieces of material break off from the corners and stress cracks tend to propagate from the chipped edges as the wafer contacts against the retaining ring. These chips and cracks generally lead to premature failure of the utility wafer.
Therefore, there is a need in the art for a utility wafer that provides a durable, low cost means for simulating a wafer in a chemical mechanical polishing system.
SUMMARY OF INVENTION
In one aspect, a utility wafer is provided which generally includes a first side and a second side opposing the first side and defining a thickness therebetween. A peripheral edge couples the first side and the second side. An edge defined at the interface of the peripheral edge and the first side is relieved, i.e., the edge has a chamfer, radius or other relief. Optionally, a second edge at the interface of the peripheral edge and the second side is also relieved. In another embodiment, the peripheral edge is polished.
In another aspect, a method for fabricating a utility wafer is provided. The method generally comprises providing a wafer having a thickness of at least about 45 mils relieving at least one edge of the wafer and polishing the wafer. In one embodiment the wafer is laser polished and annealed.
BRIEF DESCRIPTION OF DRAWINGS
The teachings of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which:
FIG. 1 is a schematic plan view of a chemical mechanical planarization system; and
FIG. 2 is an elevation of a utility wafer.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures.
DETAILED DESCRIPTION OF INVENTION
FIG. 1 depicts a schematic plan view of an exemplary chemical mechanical polisher 100 . The polisher 100 has a plurality of polishing stations 106 (e.g., three), a carousel 102 that supports four polishing heads 110 , a wafer load/unload assembly 104 , and a transfer station 108 . An input/output robot 116 loads and unloads wafers 114 to/from the transfer station 108 . Four polishing heads 110 are mounted in the carousel 102 . The carousel 102 is partially cut-away to provide a view of the components of the transfer station 108 . As such, one of the four polishing heads 110 is not shown. The carousel 102 rotates about a central axis such that any one of the polishing heads 110 may be positioned at any one of the polishing stations 106 or the transfer station 108 . Consequently, the wafer 114 can be loaded into a particular polishing head 110 , and the carousel 102 can move the head 110 to a particular polishing station 106 .
The wafer 114 may be a production wafer, a test wafer or a utility wafer. Generally, the wafer 114 is transferred between the polisher 100 and other systems (e.g., wafer cleaners) or at least one wafer cassette 128 via the wafer input/output robot 116 . The input/output robot 116 has a gripper 118 (e.g., a vacuum gripper) that retains the wafer 114 during transfer between the transfer station 108 and the wafer cassette 128 . In normal wafer processing, the wafer cassette 128 holds production wafers. During simulations of wafer processing, the wafer cassette typically holds a plurality of utility wafers 130 , and one or more test wafers 132 .
The transfer station 108 comprises at least one buffer station 120 (preferably, two buffer stations 120 A and 120 B) and a transfer robot 122 . The input/output robot 116 places the wafer 114 that is entering the polisher 100 into the input buffer station 120 B. After the transfer station 108 receives the wafer 114 from the robot 116 and the robot 116 has cleared the transfer station 108 , the transfer station robot 122 retrieves the wafer 114 from the input buffer station 120 B and moves the wafer 114 to the wafer load/unload assembly 104 . The wafer load/unload assembly 104 positions the wafer 114 into a polishing head 110 . The transfer station 108 may be of any type known in the art for transferring a wafer between input/output robot and a polishing head. Preferably, the transfer station 108 is a transfer station that is described in commonly assigned U.S. Patent application Ser. No. 09/414,771, filed Oct. 6, 1999, to Tobin, and is incorporated herein by reference.
The carousel 102 retrieves the wafer 114 from the wafer load/unload assembly 104 and proceeds to polish the wafer 114 . While the transfer robot 122 is busy moving a wafer 114 from the buffer station 120 to the wafer load/unload assembly 104 , the input/output robot 116 may position another wafer 114 into the empty input buffer station 120 B.
When the wafer 114 has completed a polishing procedure, the carousel 102 moves the wafer 114 to the wafer load/unload assembly 104 and releases the wafer 114 . The transfer robot 122 then retrieves the wafer 114 from the wafer load/unload assembly 104 and places the wafer 114 into the output buffer station 120 A. The polished wafer 114 is then retrieved from the output buffer station 120 B by the input/output robot 116 .
FIG. 2 depicts embodiment of a utility wafer 130 according to the invention. The utility wafer 130 is typically fabricated out of a ceramic material. In one embodiment, the utility wafer 130 substantially comprises quartz. The utility wafer 130 has a first side 202 , a second side 204 side and a peripheral edge 208 . Optionally, one of the first or second sides 202 , 204 may comprise a reflective coating. Generally, the first side 202 is substantially parallel to the second side 204 and defines a thickness 216 of at least 1.5 mm. One skilled in the art will appreciate that although thinner wafers will provide some utility, thicker wafers will allow for a greater number of passes through the polisher 100 . Tests have shown that a thickness of 1.5 mm will exhibit a life in excess of 100 polishing cycles.
The first side 202 and the peripheral edge 208 come together to form a first edge 206 . The second side 204 and the peripheral edge 208 come together to form a second edge 210 . At least one of the edges 206 , 210 is relieved to remove the otherwise sharp edge by chamfering, providing a radius, tapering, undercutting or other relief for removing the sharp edge.
In one embodiment the first edge 206 comprises a first chamfer 218 . The first chamfer 218 generally has an angle 212 that ranges between about 30 to about 60 degrees relative the first side 202 . One skilled in the art will appreciate that other angles 212 may be utilized. The first chamfer 218 extends a distance 214 along the peripheral edge 208 . As the utility wafer 130 is polished and material is removed from the face 202 , the distance 214 will diminish. In one embodiment, the distance 214 is at least about 0.5 mm before initial polishing. The first chamfer 218 removes the sharp corner that would otherwise be present at the interface of the first side 202 and peripheral edge 208 . The first chamfer 206 thus minimizes the probability of chipping and the propagation of stress fractures through the utility wafer 130 when the peripheral edge 208 comes into contact with other objects such as, for example, a retaining ring of the polishing head 110 . One skilled in the art will appreciate that other relief geometries, chamfer angles and distances may be readily substituted without departing from the teachings herein. For example, the first edge 206 may alternatively comprise a radius of at least 5 mils.
Optionally, the second edge 210 may comprise a second chamfer 220 opposite the first chamfer 206 . Typically, the second chamfer 220 is fabricated identically to the first chamfer 218 , although the relative geometry of the chamfers 218 , 220 will vary as the utility wafer 130 is polished. One skilled in the art will appreciate that the relief at the first edge 206 may be different than the relief at the second edge 210 , i.e., the first edge 206 may be chamfered while the second edge 210 has a radius.
In another embodiment, the peripheral edge 208 of the utility wafer 130 is optionally polished after relieving one or both of the edges 206 , 210 . Polishing generally fuses the peripheral edge 208 of the utility wafer 130 such that any cracks or chips that may be present at the peripheral edge 208 and particularly the edges 206 and 210 , do not propagate into fractures or allow chips to be generated. Moreover, the fused peripheral edge 208 typically has more impact resistance, and is less prone to chipping than a non-fused surface. Polishing is generally in the form of heat polishing such as laser polishing or flame polishing. Optionally, polishing may be followed by annealing at an elevated temperature of, for example, about 1165° C. Prior to annealing, the utility wafer 130 should be cleaned to remove surface contamination.
Referring to FIGS. 1 and 2, in operation, a simulation of a chemical mechanical planarization process can be performed by processing a plurality of utility wafers 130 through the polisher 100 , while periodically processing the test wafer 132 at predetermined intervals during the simulation. In an exemplary test sequence, approximately twenty-five utility wafers 130 and at least one test wafer 132 are loaded into the wafer cassette 128 . The input/output robot 116 retrieves one of the utility wafers 130 from the cassette 128 and places the utility wafer 130 (shown as wafer 114 retained by robot 116 ) on the transfer station 108 . The transfer station 108 transfers the utility wafer 130 to the load/unload assembly 104 where the utility wafer is loaded one of the four polishing heads 110 mounted to the carousel 102 .
The utility wafer 130 is then moved to a polishing station 106 and polished. Once polishing is complete, the utility wafer 130 is returned to the cassette 128 and another utility wafer is retrieved and polished. This sequence repeats until a predetermined quantity of utility wafers 130 are polished. If the required number of passes through the polisher 100 are greater than the number of utility wafers 130 in the cassette 128 , then the utility wafers 130 passed through the polisher more than once as required.
Once the predetermined number of utility wafers 130 have been polished, the test wafer 132 is retrieved from the cassette 128 and processed in the polisher 100 . Once processed, the test wafer 132 is returned to the cassette 128 and another sequence of polishing the utility wafers 130 are preformed. The test wafer 132 is measured (typically remotely or in the polisher 100 before transfer to the cassette 128 ) to acquire data indicative of the polishing process. An example, thickness of an oxide layer may be measured to indicate polishing rate and uniformity of the polishing process.
The cycle of polishing a number of utility wafers 130 followed by a test wafer 132 is repeated until the predetermined number of cycles through the polisher 100 have completed. Data from test wafer 132 is compiled to create a data base from which a model of the polishing process just simulated can be constructed.
Although the teachings of the present invention that have been shown and described in detail herein, those skilled in the art can readily devise other varied embodiments that still incorporate the teachings and do not depart from the spirit of the invention.
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A utility wafer, more specifically, an utility wafer for simulating a workpiece in a semiconductor processing system. The utility wafer includes a first side, a second side and a peripheral edge wherein one or both edges of the peripheral edge are relieved to remove the otherwise sharp edge. In one embodiment, the peripheral edge is polished. The utility wafer is resistant to chipping, stress cracking and breakage when undergoing chemical mechanical planarization.
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Reference is made to a microfiche appendix forming a part of this application comprising two microfiche containing 72 frames.
The present invention relates generally to computer numerical control for industrial machines and, more particularly, to a method of establishing protected or safe zones within a machine's sphere of operation and inhibiting operation of the machine when a predicted movement will intersect a protected zone.
Computer numerical controls (CNC) when applied to industrial machines permit the automation of manufacturing processes with a minimum of human intervention. Because of the lack of human observation of the process on a full time basis, there exists the possibility that a movement of a cutting tool on a machine tool or an arm mechanism on an industrial robot may result in the tool or associated tool holding mechanism or robot arm being driven into a part of the machine itself or some other stationary object. For example, in a lathe in which a part being machined, i.e., the workpiece, is held in place by the jaws of a chuck, driving the cutting tool to the end of the workpiece may force the tool into contact with the jaws of the chuck resulting either in damage to the chuck or in breakage of the cutting tool. A similar problem may exist in a milling machine in which a workpiece is held in place on a workbed by a plurality of clamps. Relative movement between the milling machine cutting tool and the machine bed on which the workpiece is held may result in the cutting tool contacting the clamps and cause damage to either the clamps or the cutting tool. A similar problem exists for robot arm movements since point-to-point movements may follow a vectorial path into which other objects may have been placed.
With machine tools, one of the reasons for the possibility that a cutting tool or other portion of a machine may hit a clamp or a chuck face is that a part program for machining a workpiece is normally written by a computer programmer, or part programmer, who writes a part program based upon a mechanical drawing of the part which it is desired to machine. At the time that the part program is generated, the programmer may not know the exact location of any clamping devices or holding fixtures which the machine operator may utilize to hold the workpiece in position. Accordingly, a movement commanded by the part program may cause the machine tool to pass through a point in space which is occupied by a holding fixture. A safe zone or a protected zone can be defined by the machine operator by entering the location into memory of each clamping or holding fixture. Typically, the defined safe zone will be a three-dimensional space within which a clamping fixture or a chuck is contained. However, it is also possible to define a zone within which a tool is permitted to enter but not to exit, i.e., a zone may be defined as a no-exit zone. An example of a no-exit zone would be one in which it is desired to drill a hole through the center of a workpiece held in a chuck. In this instance, a drill bit would be permitted to enter through the center of the workpiece but would not be allowed to go beyond a certain depth or to deviate radially from the center. Thus, there would be defined a no-exit zone within a no-entry zone.
Robot arm movements must similarly be protected from hitting stationary objects. Since the arm movements are controlled by programs just as are machine tools, zones can be defined in the same manner as for such machine tools. More particularly, a tool held by an end effector or clamp on the robot arm can be treated as though it were a cutting tool in a lathe.
The establishment of safe or protective zones within a machining sphere of operation has been known in the prior art. In prior art controls of which we are aware, safe zones may be defined by the machine operator in a manner similar to the method used in this invention. However, in the prior art controls the tool position or any other point which is being monitored is monitored on a continuous basis and operation is only inhibited when the tool or other monitored point comes into contact with the safe zone. If the machine has any degree of overtravel, once a motion stop command has been given, the tool or monitored point may enter the safe zone before coming to a halt. The safe zone must, therefore, be defined to have certain overlapping dimensions of sufficient depth to avoid having the tool or monitored point come into contact with the protected device. Thus, the prior art controls must continuously monitor tool position in order to detect intersection with a safe zone and safe zones must be defined to have sufficient dimensions to avoid collisions which could be caused by mechanical overtravel.
It is an object of the present invention to provide an improved method of machine operation utilizing safe zone controls.
It is another object of the present invention to provide an improved machine operating system which avoids the need for continuous monitoring of position with respect to each defined safe zone.
It is still another object of the present invention to provide an improved machine operating system which permits safe zones to be defined without extra dimensions to compensate for machine overtravel.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided an improved method for monitoring the location of safe zones and for inhibiting the operation of a machine when relative motion between a tool and workpiece will result in tool contact with a safe zone. In our improved method of operation, each command block of a part program is first evaluated to determine whether or not it is a move command. If the command is determined to be a move command, the start and end points of the path of travel are calculated. The path of travel of the tool in moving between the start and end points is also determined. The start and end points of the move are then compared with the previously defined safe zones to determine whether the start point is within a no-entry zone or whether the end point is outside a no-exit zone. If either situation exists, the machine operation is inhibited. The path of travel of the machine tool is then compared against the known dimensions of each safe zone and any intersection of the predicted path of travel with the safe zone will result in inhibition of that command block of information. The present invention thus contemplates that for each command block of information, the predicted path of travel and its start and end points of the move will be computed and compared against known safe zones. If the path of travel intersects a zone, the part program will be stopped and machine tool operation inhibited. In this manner, the inventive method of operation eliminates the need to continuously monitor tool position and allows for very closely defined protective or safe zones around clamping devices or other components which might interfere with tool or tool holder movement.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is simplified drawing a machine tool for purposes of illustrating a method according to the invention;
FIG. 2 is a block diagram of a computer numerical control of a type applicable for implementation of a method in accordance with the invention;
FIG. 3 is a flow chart illustrating broadly the method of the invention as applied to a machine tool of the type shown in FIG. 1; and
FIGS. 4-9 are flow charts expanding upon the flow chart of FIG. 3.
DETAILED DESCRIPTION
Referring now to FIG. 1, there is shown a highly simplified view of a machine tool, in this case a lathe, which will illustrate the use of safe zones. The CNC, the driving motors and other required elements of an operating machine tool are not shown in this figure. The machine includes a bed 10 upon which is mounted a frame 12 supporting a workpiece holding mechanism or chuck 14. The chuck 14 includes jaws 16 which can be tightened upon a workpiece 18 to hold it in position and, in the case of the illustrated lathe, provide the connection to the driving motors which enables the workpiece to be rotated for machining. While one end of the workpiece 18 is held within the jaws 16, a second end is held against a tailstock 20 and pinned in place by a center 22 held in a center holder 40. The tailstock 20 is also attached to the machine bed 10. A tool holding mechanism 24 is also mounted on the machine tool bed 10. The tool holding mechanism 24 includes a base 26 which allows the mechanism 24 to move in parallel with the lengthwise axis of the workpiece 18 and also to move in a direction perpendicular to the workpiece 18. A cutting tool 28 and tool base 30 are mounted in the tool holding mechanism 24. The base 30 is connected to the mechanism 24 in such a manner that it can be raised and lowered so as to bring the cutting tool 28 into contact with the workpiece 18.
For purposes of this discussion, the axis of motion parallel to the lengthwise axis of the workpiece will be referred to as the Z axis, the vertical axis will be referred to as the Y axis and the axis moving in and out of the paper with respect to the viewer will be referred to as the X axis. It will be appreciated that as the tool holding mechanism 24 is driven in the Z axis toward the frame 12, it becomes possible for the tool 28 to come into contact with the chuck 14. Further, if the tool 28 is driven along the Y axis at the same time, it may also come into contact with the jaws 16 of chuck 14. Similarly, any move in the Z axis direction towards the frame 20 may also result in the tool 28 or tool holder 30 or mechanism 24 coming into contact with some portion of the tailstock 20. In order to prevent such collisions from occurring, a zone 32 is defined around the chuck 14. An additional zone 34 is also formed around the jaws 16. At the tailstock end of the machine, a zone 36 is defined around the center 22 and a zone 38 is defined around the center holder 40. An additional zone 42 is also defined about a portion of the tailstock 20. Since in a lathe of the type illustrated, the position of the tool 28 in the X axis is normally fixed, the zones need only be two dimensional for this application. Accordingly, the computation of interference points need only be done with respect to lines rather than planes. However, in a milling machine or robot arm operation, the zones would more likely be three-dimensional.
As noted previously, the present invention is particularly adapted for use with a computer numerical control (CNC) in which the positioning of the cutting tool 28 with respect to the workpiece 18 is defined by a part program operating within the CNC. As is well known, part programs are divided into command moves or work statements wherein each block of information within a part program defines a unidirectional movement of the machine cutting tool 28 with respect to the workpiece 18. However, there are certain moves, such as circular arcs which are performed by "canned cycles" which can be called by command blocks within the part program. In the present invention, when a command move is generated, the CNC determines whether that move will intersect any of the protected zones on the machine tool working area. In the illustrative example, the CNC will determine whether the machine tool 28 during a prescribed movement would intersect the zones 32, 34, 36, 38 and 42. If any of the zones would be intersected by the command move, the part program would be stopped and operation of the machine tool inhibited so that an operator could be alerted and take appropriate action.
Although the cutting tool 28 may be of primary concern, it is also possible that a corner 44 of the tool base 30 might also come in contact with the chuck 14 or chuck jaws 16. For example, if the tool were moved into a position for cutting the reduced cross section 46 on the workpiece 18, it might be possible for the corner 44 to come into contact with the jaws 16. Consequently, the point 44 may be defined as an additional monitored point for which the CNC would also have to determine whether that point intersected any of the defined safe zones for any particular commanded move. Although the method of operating a machine tool system is applicable with any type of CNC, the implementation disclosed herein is particularly applicable for use with a Mark Century® 2000 CNC available from General Electric Company. The Mark Century 2000 CNC is a microprocessor based control unit employing Intel 8086 and 8087 microprocessors. The hardware architecture for the Mark Century 2000 CNC is shown in FIG. 2. The system central processing unit (CPU) 46 performs processing operations for the system and contains the Intel 8086 and 8087 microprocessors. The system dynamic ram 48 (random access memory) contains read-write memory for the system and is coupled to the system CPU and other functional portions of the system through a system bus 50. An axis controller 52 connected to the bus 50 provides several control functions for each driven axis of a machine tool 53. The axis controller 52 contains it own microprocessor which serves as a front end processor to interface a coordinated group of axes to the system bus while other processors on the controller perform computations for the control axis.
An input-output (I/O) controller 54 coordinates system bus I/O operations and serves to connect the system bus to a local I/O bus 56. The local I/O bus 56 connects the system to a non-volatile memory 58 in which the part programs and all system data which must be preserved are stored. The local I/O bus 56 is also connected to a local digital I/O 60 which is functionally associated with a machine control station 62. The local digital I/O 60 generates digitized actuator control signals and monitors the status of contact inputs.
An NC control station 64 is also connected to the I/O controller 54. The NC control station 64 serves as a front panel to machine tool operators, part programmers and designers. The machine control station 62 is a control panel from which a machine tool operator can perform manual operations and control the execution of part programs.
The CNC illustrated in FIG. 2 operates under control of the system CPU 46 executing programs resident in the system ram 48. Part programs may be input from an external device such as a paper tape or cassette reader (not shown) through the I/O controller 54 or through a keyboard on the NC control station 64. Any part program which is input to the system is stored by the I/O controller 54 into nonvolatile memory 58. The system CPU 46 directs the execution of other part programs through the I/O controller 54 and the axis controller 52. Part programmed axis commands are executed through the axis controller 52 which is connected to the machine tool 53. The machine tool 53 contains axis feed drives which are under control of the axis controller 52. Non-axis commands (e.g., coolant on or off) are executed through the I/O controller 54, connected to the machine tool 53 through the local digital I/O bus 56. Commands entered with pushbuttons and controls on machine control station 62 are communicated to the I/O controller 54 and finally to the machine tool 53 through either the axis controller 52 or the local digital I/O bus 56.
As is well known, a CNC as with most other computer control systems has evolved from a hardwired system into essentially a computer architecture which is customized into a firmware control system through the use of software. Computer programs, i.e., software, provide the method for reconfiguring each of these computer systems into a system equivalent to those earlier hardwired systems. The method disclosed in this application is thus configured in the form of a computer program which forces the hardware system illustrated in FIG. 2 to operate in a particular fashion in order to implement the improved method.
Referring now to FIG. 3, there is shown a flow chart illustrating broadly the improved method of operation as applied to a lathe of the type illustrated in FIG. 1. Safe zone checking is initiated each time that a block of data is processed by the CNC system. Before any move is initiated, the program verifies that no zones will be violated by the move. Before discussing the particular method illustrated in FIG. 3, it should be noted that the subject of safe or protective zones can be divided into three distinct areas:
(1) Bounded areas from which a tool or an optionally defined additional monitoring point may not depart.
(2) Forbidden areas into which a tool or an optionally defined additional monitoring point may not enter.
(3) Interference zones for four or more axes to prevent collisions between multiple turrets, tailstocks, chuck faces or other machine elements.
The inventive method utilized in the present invention prevents a programmed or internally generated move from becoming active if it is determined on a predictive basis that it would exceed the bounds of a defined safe zone. It should be noted that the actual location of a tool tip must also be determined before the tool tip path can be located. The tool tip position will be modified by tool offsets, tool nose radius compensation, presets, offsets and reference zero presets.
Referring again to FIG. 3, the safe zone checking module is called for each block of information within a part program and also for each manual move generated from the control station 62. A block of information may define either a move, a zone definition change or some other instruction. If the information block is merely a definition CHANGE IN A ZONE, the safe zone checking module is only called upon to establish the new desired safe zone definitions. If the command block is for a move, then the module must determine whether that move will intersect a safe zone which was previously established. Since the primary interference concern in a lathe is with the chuck, the first step is to determine the chuck dimensions. The "HAS CHUCK BEEN CHANGED" step determines if the chuck dimensions have been changed and, if so, branches to DEFINE NEW ZONE. In the block identified as ZONE CONDITION CHANGE, the program determines whether the command block is a move block or a definition change. If it is merely a definition change, the program will recognize a condition change and branch to establish the new safe zone (ESTABLISH SAFE ZONE) followed by an exit of the program. If the command block is not a zone condition change, then it could be a move command and the method then requires a check to determine whether there are additional monitoring points (ADD MONITORING POINTS). If there are additional monitoring points, then the command block is a definitional block rather than a move block and the program will then branch to CREATE A NEW ZONE RECORD in which step the new monitoring points are identified. If additional monitoring points are not being added, then the command block must be a move block and the next step is to determine whether any monitored zones are active (IS A ZONE ACTIVE) since it is possible to disable safe zones via part program input. If any zone is active, the program performs a safe zone check (PERFORM LATHE SAFE ZONE CHECK) and calculates whether the move will intersect a safe zone. After all checks have been completed, the program updates all the active safe zones and exits. If no zones are active, updates are unnecessary and the data is merely "rolled" so as to be available for the next command block.
FIGS. 4 through 8 expand upon the functions identified in the flow chart of FIG. 3. Referring now to FIG. 4 the step entitled DEFINE NEW ZONE FOR THIS CHUCK is shown in greater detail. As is illustrated, if a new zone definition is required, then a new safe zone record must be created in memory (CREATE NEW SAFE ZONE RECORD). The creation of a new safe zone record will be further described in FIG. 5. Once a safe zone record has been established, the new chuck safe zone is moved into the zone one definition
(DEFINE ZONE 1 FOR NEW CHUCK). Referring to FIG. 5, the sub-steps necessary to CREATE NEW SAFE ZONE RECORD are illustrated. The program must first determine whether or not a zone definition already exists for the required safe zone. If a zone definition does exist, the zone data is copied into a new record location. The program then moves the pointer to the active safe zone location. If the zone definition does not exist, a new record must be created and values initialized either in accordance with the information programmed from the NC control station 64 or from information supplied with the part program. Once the new record is created, the pointer is updated to point to the active safe zone information.
The process of actually checking the safe zone to determine whether an intersection will occur is illustrated in FIG. 6. The safe zone check determines first whether safe zone checking has been enabled. If checking has not been enabled, the program immediately exits. Otherwise, the program evaluates the commanded move by calculating the predicted tool path and the start and end points of the move for the tool tip. Once the start and end points and predicted tool path are calculated, the program next checks if a new zone definition exists. If a new zone has been defined, there is a possibility that the start point of the move may already violate a zone. Such may occur, for example, on initial startup of the system. Thus, the programmed method checks a safe zone violation at the current tool position. If a zone is violated, an error signal is generated and the operation of the machine tool is inhibited. If no new zone definition occurs, the current position check is skipped and the program checks to see if a zone would be intersected by the commanded move. If the move will violate a zone, an error is signalled and machine operation is inhibited. If the commanded move does not violate a zone, the program next determines whether there are additional monitoring points other than the tool tip which must be checked. The additional monitoring points are checked in essentially the same manner as the tool tip. The start point and intersection point with the defined safe zones are checked to determine if they will violate a safe zone. If any checks result in a violation of a safe zone, an error signal is generated and operation of the machine tool is inhibited. If no violations are detected, the program exits and allows the commanded move to be processed.
A flow chart for the step entitled CALCULATE PREDICTED TOOL POSITION is shown in FIG. 7. Referring now to that figure, it can be seen that the first check is to determine whether the commanded move is an auxilliary or primary axis move. For purposes of this discussion, an auxiliary axis is defined as a non-contouring axis and non-spindle axis, e.g., it may be a tool changer which is rotating or a table rotating to bring a workpiece into position. For an auxiliary axis move, the programed method performs essentially the same safe zone checks as for a primary axis. For a primary axis move, the predicted position at the start and the end of the move are determined. The exact details of the calculations are shown in detail in the program attached hereto as a microfiche appendix.
Referring now to FIG. 8, there is shown an expanded flow chart for the step CHECK IF SAFE ZONES ARE VIOLATED BY CURRENT POSITION of a monitored point. Note again that the first check for any safe zone is to determine whether or not that safe zone has been enabled for this particular move. If the safe zone is enabled, the calculations are performed. Otherwise, that zone is skipped and the next zone to be checked is processed. In zone checking, the programmed method determines whether the zone type is a no-exit or a no-entry zone. If the zone type is a no-entry zone, then a calculation must be performed to determine if the actual position at the start point of the move is inside the safe zone. If the start point is determined to be inside the zone, then an error signal is generated and the move is inhibited. If the start point is not inside a zone, then the program checks to determine if all zones have been completed and, if so, exits to the main program. If the zone type is determined to be a no-exit type of zone, then the checking will determine if the start point is outside the zone and therefore already in violation of the safe zone dimensions.
FIG. 9 illustrates the method for determining if the safe zone is intersected by a commanded move. Again the first check determines whether or not the particular zone being checked is enabled at this time. Assuming that the zone has been enabled, the potential relative movement between the tool and workpiece can be a circular arc or a linear move. If a circular arc is programmed, a unique calculation is required to determine if the arc intersects the zone. A different calculation is required to determine if a linear move, i.e., straight line, will intersect the zone. Both of these calculations are disclosed in detail in the microfiche appendix. If it is determined that a zone is intersected by a move, the programmed method evaluates whether or not the move is a JOG move, i.e., a manually forced move. Since it may be desirable to advance a tool to a location adjacent a safe zone, a JOG move is permitted to continue up to the point at which it actually intersects a safe zone. In processing the JOG move, however, the program actually calculates the closest intersection point to the JOG move and allows an operator to JOG only to that closest point, i.e., rather than permit the commanded move to be processed, the distance to the closest intersection point is substituted for the commanded move distance so that the actual move is truncated at the zone intersection point.
In order to terminate JOG moves when a limit is encountered, the direction of the JOG in each axis is determined and a maximum distance that each axis may travel without exceeding the appropriate limit is placed in a distance-to-go register. The result is that motion in a second axis may continue even if the first axis has reached its limit of travel.
Although the detailed description has been set forth with specific reference to a lathe, it will be apparent that the inventive method is equally applicable to a milling machine or a robot. In these latter applications, safe zones would more likely be defined as three-dimensional spaces thereby necessitating calculation of intersection points between a line and a plane. However, such calculations are well known and can be obtained from many geometry and calculus textbooks. It is therefore intended that the invention be given the full breadth and scope of the appended claims.
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A method for preventing interference between relatively moveable components of a computer controlled industrial machine in which the position of the moveable machine elements are controlled by a computer program. For each movement, the computer first determines a predicted path for the movement and thereafter determines whether the path will intersect a safe zone, a safe zone being defined as a zone containing an element which is to be protected from contact with the moveable element. If a predicted path intersects a safe zone, the machine operation is halted. Provision is made for manual moves, i.e., movements not directed by the computer up to the nearest intersection point with a safe zone.
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FIELD OF THE INVENTION
[0001] This invention relates to a simplified, low cost, variable nozzle to control exhaust gas flow to a turbine wheel in a variable flow turbocharger. Thus boost pressure can be modulated by controlling the nozzle flow volume. More particularly, the invention provides a variable nozzle turbocharger which produces change of turbine flow with acceptable resolution, at a cost lower than that for a VTG turbocharger. By altering the nozzle volume between the divider wall and the contour, the turbine flow to the turbine wheel can be modulated, and thus the boost level output of the turbocharger may also be modulated.
BACKGROUND OF THE INVENTION
[0002] Turbochargers are a type of forced induction system. They deliver air, at greater density than would be possible in the normally aspirated configuration, to the engine intake, allowing more fuel to be combusted, thus boosting the engine's horsepower without significantly increasing engine weight. This can enable the use of a smaller turbocharged engine, replacing a normally aspirated engine of a larger physical size, thus reducing the mass and aerodynamic frontal area of the vehicle.
[0003] Turbochargers ( FIG. 1 ) use the exhaust flow ( 100 ), which enters the turbine housing at the turbine inlet ( 51 ) of the turbine housing ( 2 ), from the engine exhaust manifold to drive a turbine wheel ( 70 ), which is located in the turbine housing. The turbine wheel is solidly affixed to a shaft, the other end of which contains a compressor wheel which is mounted to the shaft and held in position by the clamp load from a compressor nut. The primary function of the turbine wheel is providing rotational power to drive the compressor. Once the exhaust gas has passed through the turbine wheel ( 70 ) and the turbine wheel has extracted energy from the exhaust gas, the spent exhaust gas ( 101 ) exits the turbine housing ( 2 ) through the exducer ( 52 ) and is ducted to the vehicle downpipe and usually to the after-treatment devices such as catalytic converters, particulate and NO x traps.
[0004] The power developed by the turbine stage is a function of the expansion ratio across the turbine stage. That is the expansion ratio from the turbine inlet ( 51 ) to the turbine exducer ( 52 ). The range of the turbine power is a function of, among other parameters, the flow through the turbine stage.
[0005] The compressor stage consists of a wheel and its housing. Filtered air is drawn axially into the inlet ( 11 ) of the compressor cover ( 10 ) by the rotation of the compressor wheel ( 20 ). The power generated by the turbine stage to the shaft and wheel drives the compressor wheel ( 20 ) to produce a combination of static pressure with some residual kinetic energy and heat. The pressurized gas exits the compressor cover ( 10 ) through the compressor discharge ( 12 ) and is delivered, usually via an intercooler to the engine intake.
[0006] The design of the turbine stage is a compromise among the power required to drive the compressor; the aerodynamic design of the stage; the inertia of the rotating assembly, of which the turbine is a large part since the turbine wheel is manufactured typically in Inconel which has a density 3 times that of the aluminum of the compressor wheel; the turbocharger operating cycle which affects the structural and material aspects of the design; and the near field both upstream and downstream of the turbine wheel with respect to blade excitation.
[0007] Part of the physical design of the turbine housing is a volute, the function of which is to control the inlet conditions to the turbine wheel such that the inlet flow conditions provide the most efficient transfer of power from the energy in the exhaust gas to the power developed by the turbine wheel. Theoretically the incoming exhaust flow from the engine is delivered in a uniform manner from the volute to a vortex centered on the turbine wheel axis. To do this, the cross sectional area of the volute gradually and continuously decreases until it becomes zero. The inner boundary of the volute can be a perfect circle, defined as the base circle; or, in certain cases, such as a twin volute, it can describe a spiral, of minimum diameter not less than 106% of the turbine wheel diameter. The volute is defined by the decreasing radius of the outer boundary of the volute and by the inner boundary as described above, in one plane defined in the “X-Y” axis as depicted in FIG. 4 , and the cross sectional areas, at each station, in the plane passing through the “Z” axis, as depicted in FIG. 16 . The “Z” axis is perpendicular to the plane defined by the “X-Y” axis and is also the axis of the turbine wheel.
[0008] The design development of the volute initiates at slice “A”, which is defined as the datum for the volute. The datum is defined as the slice at an angle of “P” degrees above the “X-axis of the turbine housing containing the “X”-axis, “Y”-axis and “Z”-axis details of the volute shape.
[0009] The size and shape of the volute is defined in the following manner: The widely used term A/R represents the ratio of the partial area at slice “A” divided by the distance from the centroid ( 161 ) of the shaded flow area ( 160 ) to the turbo centerline. In FIGS. 15A and 15B the centroids ( 161 ) determine the distance R A and R B to the turbo centerline. For different members of a family of turbine housings, the general shape remains the same, but the area at slice “A” is different as is the distance R A . The A/R ratio is generally used as the “name” for a specific turbine housing to differentiate that turbine housing from others in the same family (with different A/R ratios). In FIG. 15A . the volute is that of a reasonably circular shape. In FIG. 15B the volute is that of a divided turbine housing which forces the shape to be reasonably triangular. Although the areas at slice “A” for both volutes are the same, the shapes are different and the radii to the centroids are different (due to the volute shape), so the A/Rs will be different. Slice “A” is offset by angle “P” from the “X”-axis. The turbine housing is then geometrically split into equal radial slices (often 30°, thus at [30x+P]°, and the areas (A A-M ) and the radii (R A-M ) along with other geometric definitions such as corner radii are defined. From this definition, splines of points along the volute walls are generated thus defining the full shape of the volute. The wall thickness is added to the internal volute shape and through this method a turbine housing is defined.
[0010] The theoretically optimized volute shape for a given area is that of a circular cross-section since it has the minimum surface area which minimizes the fluid frictional losses. The volute, however, does not act on its own but is part of a system; so the requirements of flow in the planes from slice “A”, shown in FIG. 4 to the plane at slice “M”, and from “M” to the tongue, influence the performance of the turbine stage. These requirements often result in compromises such as architectural requirements outside of the turbine housing, method of location and mounting of the turbine housing to the bearing housing, and the transition from slice “A” to the turbine foot ( 51 ) result in turbine housing volutes of rectangular or triangular section, as well as in circular, or combinations of all shapes. The rectangular shape of the volute ( 53 ) in FIG. 1 , showing a section “D-K” is a result of the requirement not only to fit VTG vanes into the space such that the flow is optimized through the vanes and that the vanes can be moved and controlled by devices external to the turbine housing, but also to minimize the outline of the turbine housing so the turbocharger fits on an engine.
[0011] The turbine housing foot is usually of a standard design as it mates to exhaust manifolds of many engines. The foot can be located at any angle to, or position relative to, the “volute”. The transition from the foot gas passages to the volute is executed in a manner which provides the best aerodynamic and mechanical compromise.
[0012] The roughly triangular shape of the volute in FIG. 2 , taken at the same sections as those above, is the more typical volute geometry for fixed and wastegated turbine housings. The addition of the divider wall ( 21 ) is to reduce aerodynamic “cross-talk” between the volutes in an effort to maintain pulse flow, from a divided manifold, to harvest the pulse energy in the work extracted by the turbine wheel. The pressure pulses in the exhaust manifold are a function of the firing order of the engine.
[0013] Turbine housings are typically designed in families (typically up to 5 in a family) which use turbine wheels of the same diameter, or a group of wheels with close to the same diameter. They may use the same turbine foot size. For example, a family of turbine housings for a 63 mm turbine wheel may cover a range of A/Rs from 1.8 to 2.2. FIG. 5 depicts the area schedule for three volutes of a family. The largest volute is a 1.2 A/R volute, shown by the dotted line ( 40 ). The smallest volute is a 0.8 A/R volute; shown by the dashed line ( 41 ) and the mean volute, in the middle of the family, is shown by the solid line. The X-axis depicts the angle of the slice, from 30° (section “A”) to 360° (the tongue); the Y-axis depicts the area of the section at the respective angle.
[0014] Some turbine wheels are specifically designed to harness this pulse energy and convert it to rotational velocity. Thus the conversion of pressure and velocity from the exhaust gas for a pulse flow turbine wheel in a divided turbine housing is greater than the conversion of pressure and velocity from a steady state exhaust flow to the turbine wheel velocity. This pulse energy is more predominant in commercial Diesel engines, which operate at around 2200 RPM, with peak torque at 1200 to 1400 RPM, than in gasoline engines which operate at much higher rotational speed, often up to 6000 RPM, with peak torque at 4000 RPM so the pulse is not as well defined.
[0015] The basic turbocharger configuration is that of a fixed turbine housing. In this configuration the shape and volume of the turbine housing volute ( 53 ) ( FIG. 1 ) is determined at the design stage and cast in place.
[0016] The next level of sophistication is that of a wastegated turbine housing. In this configuration the volute is cast in place, as in the fixed configuration above. In FIG. 2 , the wastegated turbine housing features a port ( 54 ) which fluidly connects the turbine housing volute ( 53 ) to the turbine housing exducer ( 52 ). Since the port on the volute side is upstream of the turbine wheel ( 70 ), and the other side of the port, on the exducer side, is downstream of the turbine wheel, flow through the duct connecting these ports bypasses the turbine wheel ( 70 ), thus not contributing to the power delivered to the turbine wheel.
[0017] The wastegate in its most simple form is a valve ( 55 ), which can be a poppet valve. It can be a swing type valve similar to the valve in FIG. 2 . Typically these valves are operated by a “dumb” actuator which senses boost pressure or vacuum to activate a diaphragm, connected to the valve, and operates without specific communication to the engine ECU. The function of the wastegate valve, in this manner, is to cut the top off the full load boost curve, thus limiting the boost level to the engine. The wastegate configuration has no effect on the characteristics of the boost curve until the valve opens. More sophisticated wastegate valves may sense barometric pressure or have electronic over-ride or control, but they all have no effect on the boost curve until they actuate to open or close the valve.
[0018] FIGS. 6A and 6B represent compressor maps. The “Y” axis ( 61 ) represents the boost or pressure ratio level and the “X” axis ( 60 ) represents the expansion ratio. FIG. 6A depicts the boost curve ( 67 ) for a fixed turbine housing. In this configuration as the turbo speed rises the upper part ( 65 ) of the boost curve continues to increase in pressure ratio as the mass flow through the wheel continues to increase. FIG. 6B depicts the boost curve ( 68 ) for a wastegated turbine housing of the same A/R as that for FIG. 6A , or a wastegated turbine housing in which the wastegate valve did not open. In FIG. 6B it can be seen that the lower shape of the boost curve ( 68 ) is exactly the same as the lower part boost curve ( 67 ) in FIG. 6A to the point ( 66 ) at which the valve opens. After this point, the boost curve ( 62 ) is relatively flat, so as the turbo speed increases the boost curve is controlled at a max. level while the massflow through the wheel continues to increase. While a wastegate can be used to limit boost levels, its turbine power control characteristics are rudimentary and coarse.
[0019] A positive byproduct of wastegated turbine housings is the opportunity to reduce the A/R of the turbine housings. Since the upper limit of the boost is controlled by the wastegate, a reduction in A/R can provide better transient response characteristics. If the wastegated turbocharger has a “dumb” actuator, which operates on a pressure or vacuum signal only, and is operated at altitude, then the critical pressure ratio at which the valve opens is detrimentally affected. Since the diaphragm in the actuator senses boost pressure on one side, and barometric pressure on the other, the tendency is for the actuator to open later (since the barometric pressure at altitude is lower than that at sea level) resulting in over-boost of the engine.
[0020] Engine boost requirements are the predominant drivers of compressor stage selection. The selection and design of the compressor is a compromise between the boost pressure requirement of the engine; the mass flow required by the engine; the efficiency required by the application; the map width required by the engine and application; the altitude and duty cycle to which the engine is to be subjected; the cylinder pressure limits of the engine; etc.
[0021] The reason this is important to turbocharger operation is that the addition of a wastegate to the turbine stage allows matching to the low speed range with a smaller turbine wheel and housing. Thus the addition of a wastegate brings with it the option for a reduction in inertia. Since a reduction in inertia of the rotating assembly typically results in a reduction of particulate matter (PM), wastegates have become common in on-highway vehicles. The problem is that most wastegates are somewhat binary in their operation, which does not fit well with the linear relationship between engine output and engine speed.
[0022] The next level of sophistication in boost control of turbochargers is the VTG (the general term for variable turbine geometry). Some of these turbochargers have rotating vanes; some have sliding sections or rings. Some titles for these devices are: Variable turbine geometry (VTG), Variable geometry turbine (VGT), variable nozzle turbine (VNT), or simply variable geometry (VG).
[0023] VTG turbochargers utilize adjustable guide vanes FIGS. 3A and 3B , rotatably connected to a pair of vane rings and/or the nozzle wall. These vanes are adjusted to control the exhaust gas backpressure and the turbocharger speed by modulating the exhaust gas flow to the turbine wheel. In FIG. 3A the vanes ( 31 ) are in the minimum open position. In FIG. 3B the vanes ( 31 ) are in the maximum open position. The vanes can be rotatably driven by fingers engaged in a unison ring, which can be located above the upper vane ring. For the sake of clarity, these details have been omitted from the drawings. VTG turbochargers have a large number of very expensive alloy components which must be assembled and positioned in the turbine housing so that the guide vanes remain properly positioned with respect to the exhaust supply flow channel and the turbine wheel over the range of thermal operating conditions to which they are exposed. The temperature and corrosive conditions force the use of exotic alloys in all internal components. These are very expensive to procure, machine, and weld (where required). Since the VTG design can change turbocharger speed very quickly, extensive software and controls are a necessity to prevent unwanted speed excursions. This translates to expensive actuators. While VTGs of various types and configurations have been adopted widely to control both turbocharger boost levels and turbine backpressure levels, the cost of the hardware and the cost of implementation are high.
[0024] In order to keep flow attached to the volute walls and to keep the shape of the volute appropriate to the function of the volute, an A/R schedule is plotted, as in FIG. 5 , to ensure that there exist no inappropriate changes in section. In FIG. 5 , the “X” axis is the angle for each section. The angles could be substituted by the defining letters “A” though “M” as used in FIG. 4 . The “Y” axis depicts the radius of the section. The dotted line ( 40 ) is the area schedule for the largest A/R of the family. The dashed line ( 41 ) is the area schedule for the smallest A/R of the family.
[0025] If one considers a wastegated turbo as a baseline for cost, then the cost of a typical (VTG) in the same production volume is from 270% to 300% the cost of the same size fixed, turbocharger. This disparity is due to a number of pertinent factors from the number of components, the materials of the components, the accuracy required in the manufacture and machining of the components, to the speed, accuracy, and repeatability of the actuator. The chart in FIG. 7 shows the comparative cost for the range of turbochargers from fixed to VTGs. Column “A” represents the benchmark cost of a fixed turbocharger for a given application. Column “B” represents the cost of a wastegated turbocharger for the same application, and column “C” represents the cost of a VTG for the same application.
[0026] Thus it can be seen that for both technical reasons and cost drivers that there needs to be a relatively low cost turbine flow control device which fits between wastegates and VTGs in terms of cost. The target cost price for such a device needs to be in the range of 145% to 165% that of a simple, fixed turbocharger.
SUMMARY OF THE INVENTION
[0027] The present invention relates to a simplified, low cost, variable nozzle to control exhaust gas flow to a turbine wheel in a variable flow turbocharger. The boost pressure can be modulated by controlling the nozzle flow volume. The invention is based on the idea that flow path of exhaust gas to the turbine wheel ( 70 ) of a twin volute turbocharger is influenced by the shape and size of the nozzle formed by the shape ( 22 ) of the divider wall ( 21 ) and the shape of the flow passage determined by the walls ( 85 , 86 ) of the turbine housing. By moving the walls ( 85 , 86 ) toward, or away from the divider wall, the flow of exhaust gas through the nozzle, to the turbine wheel ( 70 ) can be modulated, which thus modulates the turbocharger boost pressure. In another embodiment, the nozzle formed by these walls and the divider wall is changed by rotating cylinders ( 58 , 59 ) containing these walls such that the gap to the divider wall is changed, modulating the exhaust flow to the turbine wheel ( 70 ) and thus modulating the boost pressure. In yet another embodiment, the divider wall is constructed as a separate component, with the inner tip of the divider wail designed as a spiral, changing the “tip-to-tip” ratio to the turbine wheel at given sections. Rotation of the spiral divider wall changes the nozzle width as described above to modulate the turbine flow and thus boost pressure. The invention also applies to single volute turbines.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The present invention is illustrated by way of example and not limitation in the accompanying drawings in which like reference numbers indicate similar parts, and in which:
[0029] FIG. 1 depicts the section for a typical VTG turbocharger;
[0030] FIGS. 2 A,B depict a pair of sections of a typical wastegated turbocharger;
[0031] FIGS. 3 A,B depict a pair of sections of a typical VTG turbocharger;
[0032] FIG. 4 depicts a section of a typical fixed turbine housing showing construction radial lines;
[0033] FIG. 5 is a chart of cross-sectional area development;
[0034] FIGS. 6 A,B depict the compressor maps for a typical fixed, and a wastegated turbocharger;
[0035] FIG. 7 is a chart showing turbocharger relative costs;
[0036] FIGS. 8 A,B depict a pair of sections of the first embodiment of the invention;
[0037] FIG. 9 depicts a magnified section of FIG. 8A ;
[0038] FIG. 10 depicts a section of the second embodiment of the invention;
[0039] FIGS. 11 A,B depict a pair of magnified sections of FIG. 11 ;
[0040] FIGS. 12 A,B depict the third embodiment of the invention;
[0041] FIGS. 13 A,B,C depict magnifications of FIG. 12 at three different slices:
[0042] FIG. 14 depicts a side view of the third embodiment and;
[0043] FIGS. 15 A,B depict the sections of some volutes at slice “A”;
DETAILED DESCRIPTION OF THE INVENTION
[0044] Since the use of vanes in variable geometry turbochargers attenuates the pulse flow component available in the exhaust flow, the inventors sought to be able to modulate turbine flow to the turbine wheel, while maintaining the pulse energy in the exhaust flow. To do this the inventors found that by modifying the nozzle formed by the divider wall on one side, and the contour surfaces in the turbine housing, on the other side, the turbine flow could be modulated without loss of pulse energy.
[0045] The first embodiment of this invention can be seen in FIG. 9 . In this embodiment a cylindrical portion of the contoured surface ( 86 ) adjacent to the divider wall surface ( 22 ) is formed on an end face of a cylinder ( 59 ) configured to move towards, and away from, the divider wall in a direction parallel to the turbocharger axis. By a like configuration, the contoured surface ( 85 ) leading to the turbine wheel ( 70 ) is formed on a face of a cylinder ( 58 ) which is also moveable closer to, and further from, the divider wall.
[0046] As can be seen in FIGS. 8A and 8B , when the contoured surfaces move, the nozzle formed by the contoured surfaces ( 85 and 86 ) and the adjacent surfaces ( 22 ) on the divider wall ( 21 ) can be manipulated. This manipulation causes the flow thorough the nozzle to change in a modulatable fashion which controls the flow to the turbine wheel. FIG. 8A shows the contoured surfaces in the retracted position. FIG. 8B shows the contoured surfaces in the extended position.
[0047] Depending upon the flow requirement, both inner and outer cylinders can be moved in synchrony. If in the management system of an internal combustion engine, combustion chamber de-activation is used, or in the case of fewer than the total number of engine combustion chambers providing only EGR flow, the flow into the exhaust manifold, and hence the pressure and flow in the turbine housing, is unbalanced so the cylinders ( 58 , 59 ) containing the contoured surfaces ( 85 , 86 ) could move asymmetrically. The configuration shown for the invention is that of a divided turbine housing as depicted in FIG. 15B . In that turbine housing volute configuration, the sensitivity of the nozzle formed by the proximity of the contoured surfaces and the divider wall, may allow asymmetric movement of the cylinders ( 58 , 59 ) containing the contoured surfaces ( 85 , 86 ). In the case of an open turbine housing volute (ie one with no divider wall) as depicted in FIG. 15A , it is assumed that with less sensitivity, both cylinders ( 58 , 59 ) containing the contoured surfaces ( 85 , 86 ), would move.
[0048] While there can be many methods which will move these “cylinders” (pneumatic, hydraulic, electro-mechanical, etc.), for the purpose of understanding the invention, one method will be described.
[0049] Since the divider wall ( 21 ) is part of the turbine housing casting, it is not possible to fit the rings from the inside of the housing. In order to fit them from the outside the cylinders ( 59 , 58 ) are mounted in an outer housing ( 80 ) which fits into a bore ( 82 ) in the turbine housing. Within this outer cylinder are pistons ( 81 ) which are sealed with “O” ring seals ( 84 ) to provide seals between the inside diameter bores of the cylinder and the outside edges of the pistons. The pistons also can carry piston rings ( 83 ) to seal gas pressure from the exhaust flow in the turbine housing, from the hydraulic compartments. There could also be gas seals on the inner and outer walls of the cylinders ( 58 and 59 ) to seal gas pressure against the bores, in which they are located. Pneumatic or hydraulic pressure is delivered to the turbine housing through a series of galleries to provide flow and pressure to the cylinders ( 58 , 59 ), causing motion towards, or away from the center line of the volute. The pressure to the inner cylinder may be supplied through the bearing housing. The closure to the open face of the outer and inner cylinders is provided by the adaptor ( 23 ) which not only provides a face to the pressure “O” rings on each pressure gallery, but also provides the interface mechanism to locate and retain the vehicle down pipe.
[0050] In a second embodiment of the invention, the contoured surfaces ( 85 , 86 ) are again mounted on cylinders ( 58 , 59 ). Whereas in the first embodiment the cylinder, upon which are mounted contoured surfaces, moves axially to modify the nozzle ( 39 ) formed by the contoured surface and the adjacent surfaces ( 22 ) of the divider wall, in the second embodiment the cylinder is made to rotate about the turbocharger axis thus changing the nozzle volume.
[0051] In this second embodiment the inventors realized that the position and shape of the divider wall, with respect to the turbine housing is relatively constant. The shape and axial position of the contoured surfaces ( 86 and 85 ) can be made to match the flow from the varying sections (“A” through “M” FIG. 4 ) to the turbine wheel. In FIGS. 11A and 11B it can be seen that the inside slope of the lines ( 87 , 88 ) connecting the contoured surfaces ( 86 and 85 ) are angled to the divider wall centerline (D-K). The nozzle volume at slice “D” being greater than the nozzle volume at slice “G”. By rotating the cylinder ( 86 ) about the axis of the turbocharger, the space “B” in FIG. 11A , between the divider wall centerline (D-K) and the surface inner wall ( 87 ) is reduced to the space “B” in FIG. 11B .
[0052] In a similar manner on the inner cylinder ( 58 ) by rotating the inner cylinder ( 58 ) about the turbocharger axis, the space “A” between the divider wall centerline (D-K) and the surface inner wall ( 88 ) in FIG. 11A and the space “A” in FIG. 11B is reduced.
[0053] As in the first embodiment a cover plate or closure ( 23 ) is mounted to the turbine housing to provide both a closure to the entry point of the cylinder ( 59 ) and to provide the interface mechanism to locate and retain the vehicle down pipe.
[0054] Since the cylinder ( 58 ) on the bearing housing side of the turbine housing can be fitted from the joint of the turbine housing to the bearing housing, there exist numerous options for the method of insertion and sealing. The power to drive the rotation of said cylinders ( 58 , 59 ) can be hydraulic pneumatic, electric, electro-mechanical, or mechanical, the choice typically being driven by the options given the turbocharger manufacturer by the engine/vehicle manufacturer.
[0000] The third embodiment of this invention involves the same aerodynamic adjustment of the nozzle but in a more complex manner.
[0055] Since the distance from the tip of the divider wall to the tip of the turbine wheel, ( FIG. 13 “T”) often referred to as the “tip-to-tip” ratio, is critical to performance, the tip to tip ratio should be kept to no less than 106% of the turbine wheel diameter for blade excitation reasons, and no more than 106% for efficiency reasons. In FIG. 13 , for a turbine wheel diameter of “R” the ratio would be:
[0000]
(
“
R
”
+
”
T
”
)
”
R
”
[0000] With a cast divider wall, in a cast turbine housing, the dross generated by the casting process is driven to the tip of the thin divider wall which produces an undesirable material composition at the tip of the divider wall. This low quality material has a tendency to prematurely fatigue and fall out of the divider wall into the turbine wheel, damaging the turbine wheel. To prevent this occurrence, the divider walls are cast thicker than would be aerodynamically desired, and shorter (thus further from the optimum tip-to-tip ratio) to minimize the thermal stress in the divider wall.
[0056] The inventors realized that if the divider wall was not cast in the turbine housing casting process but manufactured, externally from the turbine housing, from a higher quality material than that of the turbine housing casting, then the tip-to-tip clearance could be made to the minimum ratio to provide maximum performance. They also came to realize that if the divider wail was made outside of the turbine housing casting process, that the inside edge, the tip of the divider wall, could describe a spiral from the normal tip-to-tip ratio, to the optimum tip-to-tip ratio and that if the divider wall profile was sufficiently “fat” that rotation of the divider wall could change not only the nozzle volume, but also the tip-to-tip ratio and thus provide a variable flow and efficiency tool.
[0057] In FIG. 12A the outer edge ( 121 ) of the divider wall describes a constant radius. The inside edge of the divider wall ( 120 ) describes a spline, or spiral. As shown in FIGS. 13 , A, B, C, mounted on the outer end of the divider wall is a plurality of rollers ( 122 ), which fit into a groove ( 123 ), provided in one part of the turbine housing ( 124 ). Another part of the turbine housing ( 125 ) provides the closure to both capture the rollers, and to seal the two parts of the turbine housing together. In FIG. 14 it can be seen that the constant radius ( 121 ) sits outside of the volute ( 140 ) and the fasteners which are required to join the inner part ( 125 ) of the turbine housing to the outer part ( 124 ) of the turbine housing are shown. While these fasteners allow ease of assembly and disassembly, the two parts of the turbine housing could be fastened in any manner from welding to a purely mechanical method.
[0058] Since the divider wall both initiates and terminates at the tongue, accommodation has to be made in the tongue to allow the rotatable divider wall to rotate into, and out of a “housing” so that the rotation of said divider wall does not result in a gap in the divider wall. This can be done, without affecting the A/R at the start and finish of the tongue (section M to A) by adjusting the shape of the tongue and accommodating for the volume in another wall, while maintaining the area at the pertinent section.
[0059] Now that the invention has been described,
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The flow path of exhaust gas to the turbine wheel ( 70 ) of a twin volute turbocharger is influenced by the shape and size of the nozzle formed by the shape ( 22 ) of the divider wall ( 21 ) and the shape of the flow passage determined by the walls ( 85, 86 ) of the turbine housing. By moving the walls ( 85, 86 ) toward, or away from the divider wall, the flow of exhaust gas through the nozzle, to the turbine wheel ( 70 ) can be modulated, which thus modulates the turbocharger boost pressure. The invention also applies to single volute turbines.
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BACKGROUND OF THE INVENTION
The present invention relates to the protection of civilian populations of large cities against the effects of nuclear weapons, should a nuclear war occur.
Ever since the late 1950's, when the danger of a nuclear attack upon civilian population centers began to materialize, the protection of such population, to assure its long term survival under acceptable conditions, has become a problem of enormous magnitude. More recently, because of the increased capability of potential enemies to deliver such weapons with an awesome accuracy, in large quantities, the survival of our civilization has even become questionable on a global scale.
In the continental United States, no practical plans, no well prepared hosting areas even exist to receive and care for the civilians and officials who are willing to attemp to survive, at their own cost if need be. To assure the healthy survival of those who wish to be able to go through a nuclear holocaust unhurt, three conditions must be met: (1) Put distance between the explosion and the survivors-to-be, (2) Have time to wait, while being protected (if there is any fallout), and finally (3) Have shelter, supplies, facilities, amenities and talent to help and assist these aspiring survivors for a time period of up to several weeks (if there is fallout). This can best be achieved through and coordinated efforts of all the members of a large group of people, well integrated and diversified in terms of abilities, talents and experience.
It is therefore desirable to plan, develop and implement the establishment of camp sites, the construction of structures, the setting up of equipments and facilities in advance and to have them ready to be occupied and to operate, should the need for population evacuation suddenly arise. Conventional buildings are neither designed, equipped, arranged, oriented nor constructed to provide adequate protection, even when located 35-40 miles from a one-mile altitude 20-MT nuclear explosion. Preferable, such developments should be made possible at costs and in times small enough to be meaningful. Also, it is preferable that such camp sites and the structures thereon be usable at all times for the enjoyment and benefit of those who so wish at cost, for obvious economical and maintenance reasons.
SUMMARY OF THE INVENTION
It is therefore a primary object of the present invention to provide a camp site, structures, amenities and facilities to those who, as a group, wish to attempt to survive a nuclear attack on or near their city.
It is another object of the present invention to provide equipment, managerial and technical staffing to the evacuees, to maximize their chances of meaningful survival.
It is another object of the present invention to provide assistance, food, supplies and medical care to the evacuees in a manner such that they survive physically and mentally healthy so that they, in turn, are in a condition to assist those less fortunate who are in need, outside the camp, later on.
It is another object of the present invention to provide education, instruction and training to potential evacuees prior to an emergency so that evacuees are better prepared to accept and to live through the ordeal of attempting to survive.
It is another object of the present invention to provide the means for detecting, monitoring and readying for a nuclear explosion and its effects on the camp and its occupants.
Accordingly, the present invention provides structures to resist blast, equipment and installations to wash off or clean vacuum fallout dust, facilities to care for the evacuees and attending personnel to keep them physically and mentally healthy. Preferably, this is accomplished within 25 to 35 miles from likely target points, and on a scale large enough to accommodate a minimum of several hundred individuals in each camp.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partial plan view of the building and grounds layout of the camp site.
FIG. 2 is a sectional view taken along line 2--2 of FIGS. 1 and 3.
FIG. 3 is a partial view of the floor plan of the residential section of the building.
FIG. 4 is a partial midsectional elevation view taken along line 4--4 of FIG. 1.
FIG. 5 is a partial sectional view of a typical structural rigid wall.
FIG. 6 is a partial sectional view of the mast and protection wall taken along line 6--6 of FIG. 1.
FIG. 7 is a partial sectional view taken along line 7--7 of FIG. 1, of the moat, the protection wall and the bridge.
FIG. 8 is a partial elevation view of the wall and gate assembly seen from inside the camp.
FIG. 9 is a detailed partial cross-sectional view of the bottom part of the gate guiding system.
FIG. 10 is a partial midsectional elevation view of a typical building junction taken along line 10--10 of FIG. 1.
FIG. 11 is a partial midsectional elevation view of the central structure taken along line 11 of FIG. 1.
FIG. 12 is a detailed partial sectional view of the central dome wall taken along line 12--12 of FIG. 13.
FIG. 13 is a partial top view of the central dome cover.
FIG. 14 is a detailed partial sectional view taken along line 14--14 of FIG. 13.
FIG. 15 is a combined midsectional elevation and external view of the vacuum cleaning robot.
FIG. 16 is a partial sectional view taken along line 16--16 of FIG. 15.
FIG. 17 is a detailed partial midsectional side elevation view of the cleaning robot driving wheel taken along line 17--17 of FIG. 18.
FIG. 18 is a detailed partial midsectional elevation view of the cleaning robot driving wheel.
FIG. 19 is an enlarged detailed sectional view of the robot driving wheel electrical slip switching mechanism.
FIG. 20 is an enlarged detailed sectional view of the dust evacuation tube of the cleaning robot.
FIG. 21 is an enlarged detailed sectional view of the anchoring system of the rigid structure wall.
FIG. 22 is a partial sectional view of the ground-embedded vacuum tube connection and closing cap.
FIG. 23 is a midsectional elevation view of a fallout dust dumping well.
FIG. 24 is a midsectional elevation view of a sand mound trap for fallout dust, taken along line 24--24 of FIG. 25.
FIG. 25 is a top view of a sand mound trap.
FIG. 26 is a schematic layout of the fallout dust disposing pipes inside the sand mound trap.
FIG. 27 is a midsectional elevation view of a fallout dust disposing pipe taken along line 27--27 of FIG. 24.
FIG. 28 is a sectional view taken along line 28--28 of FIG. 27, of a fallout dust disposing pipe in a sand mound.
FIG. 29 is a midsectional elevation view of the central vacuum powering system.
FIG. 30-A is a detailed midsectional elevation view of a ground vacuum tube connection.
FIG. 30-B is a detailed midsectional elevation view of the end conection of a cleaning robot evacuation tube.
FIG. 31 is a detailed partial midsectional elevation view of the end of a vacuum tube, shown engaged and locked into a ground-embedded vacuum tube connection.
FIG. 32 is a partial side elevation view of the actuating means of the fallout dust tube connecting end, for ground use.
FIG. 33-A is a detailed partial midsectional view of the fallout dust tube connection end for wall connection, taken along line 33-A--33-A of FIG. 33-B.
FIG. 33-B is a side elevation view of the fallout dust tube end for wall connection.
FIG. 34-A is a detailed partial midsectional elevation view of a typical vacuum robot tube articulation taken along line 34-A--34-A of FIG. 34-B.
FIG. 34-B is a detailed partial sectional view taken along line 34-B--34-B of FIG. 34-A.
FIG. 35 is diagram curve showing how the shock wave pressure varies with time as the shock wave passes by.
FIG. 36 is a diagram curve showing how a typical fallout radiation level decays with time.
FIG. 37 is a diagrammatic view of a sensing device for detecting a nuclear explosion at a distance.
FIG. 38 is a diagram curve showing how the light flash from a nuclear explosion varies as the viewing angle deviates from the exact line of sight.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGS. 1 to 4, the nuclear war group survival camp site generally comprises a plurality of structures 1 erected on pre-improved grounds 3 to provide shelter and living accommodations to a group of people. Within a complex, structures 1 are interconnected by corridors 5 in a manner such that living quarters 7 communicate with common quarters 9, centrally located so that the occupants need not leave the shelter means provided by structures 1, in case of emergency. An emergency condition exists when a nuclear attack is anticipated and after it has occured, as long as the surroundings outside structures 1 present some health hazard. Living quarters 7 generally include a residence room 9, a bathroom 11 and closet space 13 located back to back on each side of separation walls 15, between two adjacent living quarters 7. Living quarters 7 are arranged on each side of corridors 5 and can be entered through two doors 17 and 19. Access door 17 opens on the outside, entrance door 19 opens into corridor 5. In case of emergency, only doors 19 are to be used and doors 17 are locked. Windows 21 and 22 provide light and fresh air to residence rooms 9 and bathrooms 11. Under emergency conditions, all windows are also locked. All access doors and windows are equipped with locking means, not accessible to the occupants, but monitored and controlled only by management.
All structures housing the occupants' living quarters are constructed to provide an outer shell 30 anchored to foundations 32 and solidly attached to all internal walls 15, 34 and 36 which support ceilings 38 over the living quarters and corridors. All fresh air ducts 40, air conditioning ducts 42, electrical conduits 44, cold water pipes 46 and communication lines 48 are located in the space provided between ceilings 38 and the upper part of outer shell 30 which also plays the role of a conventional roof. Hot water pipes and used water pipes are located inside ducts 50 which service each living quarter and that are connected to a central duct 52 connecting all living quarters. A plurality of sewer pipes 54 connect each bathroom to a sewer duct 56 that connects all individual sewer pipes to central sewer disposal connections 58. The sewage is disposed of by conventional means: septic tanks, leach fields or sewage processing plant as is most desirable for each camp site. Outer shells 30 are built to withstand external air pressures well in excess of the air pressure inside the living quarters. To that effect, structural shell 30 presents no flat surface, to avoid local buckling, and structural integrity throughout its thickness, as shown in FIG. 5 in which a partial section of the outer shell is depicted. Two concentric thin shells 70 and 72 made of strong materials are affixed on both sides of a light density core material 71 to form the sandwiched thicker shell. This structural shell is continuous throughout a whole complex, except where openings are required for doors, windows and connections such as 74 to other outer shells within the complex. Other complexes can be located in the vicinity and all interconnected to that which is described herein and between themselves, either underground or by above ground tunnels constructed in a similar fashion. Ends of outer shell structures such as 75 are terminated by partially ellipsoidally shaped shells to provide strength, as explained earlier.
Along the centerline of each outer shell and above the shell top, water pipes 80 are provided to feed a continuous network of sprinklers 82 arranged to reach all open surfaces within a complex as defined by outer perimeter line 90. All surfaces of both structures and ground can thus be washed. The used washing water is evacuated by gravity through underground ducts such as 92 outside of perimeter 90. The sprinkler system receives its water through feed lines 84 connected to cold water supply lines such as 46. Each complex or group of complexes is surrounded by a wall 100 of height H ranging from 8 to 10 ft. It is backed on the outside by abutting shell 102 with inner volume 104 being filled with dirt. The inner surface of wall 100 is the complex perimeter line 90. On the outer side of wall 100, a moat 106 runs the length of perimeter 90, and of wall 100, and is filled with water 108 to a depth D and over a width W. The moat has a threefold purpose, to act as a: a reservoir for the washing water, a dump for the radioactive washed off dust and a natural defense barrier. Wall 100 has a twofold purpose: to shield the occupants from radiations coming from outside the camp site and to offer another natural defense barrier. A gutter 110 runs along wall 100 to help evacuate the runoff water in addition to ducts 92 that collect water mostly inside enclosed patios areas 4 between the structures (collection points 6). The wall of moat 106 has a concrete shell 112 designed to minimize the loss of water into the ground. Access to the camp site is through bridges 120 that have side walls 123 for protection and to act as additional radiation shields. The entrance into the camp site is through wall 100 by means of sliding double gates 122 and 124, actuated by hydraulic actuators 126 and 128. The actuating hydraulic fluid comes through underground lines 130 and 132 from a pump and control means 134 housed at the end of the closest structure in a service room 136. Gates 122 and 124 roll on a plurality of spheres 140 mounted and centered in a U-shaped track 142 anchored in the ground concrete. The track is part of gate frame 144 that is solidly attached to wall 100, on the internal surface of that wall, as shown in FIGS. 7-9.
Referring to FIGS. 1 and 10 to 14, the central part of each complex houses the main service areas 150 and a quasi "open sky" dome 157, over the common area 152 which is used by the occupants for various every day activities. The structures protecting the service and common areas are of two basically different types: the rigid semi-toroidal structure 155 and the dome flexible wall structure 157. When subjected to external pressure, the rigid structure resists and hardly deforms, the flexible structure yields and deforms appreciably, but comes back to its original shape without breaking. It is practical to build rigid structures of the size of the outer shells to withstand differential pressures of a few pounds per square inch (psi). However, it is not practical (economical) to build rigid structures of a much larger size, such as that of dome 157, especially when not needed as is discussed later. The rigid hemishperical structures such as 159 connecting the living quarter structures 1 can also be constructed like outer shell 1, because their dimensions are not much larger than those of outer shell 1. These hemispheres shelter additional service areas and spaces 151. Flexible dome structure 157 of FIGS. 11 to 14 comprises anchoring rigid hollow ring 160 connected to hollow ribs 162 which join together at the top through rigid hollow torus 164 mounted on sliding sleeve 166. Sleeve 166 can slide on mast 168 up to a fixed height determined by top flange 170 solidly attached to mast 168. Torus 164, ribs 162 and hollow ring 160 all communicate and are pressurized by compressed air through air line 172 connected by air line 174 to an air compressor housed in space 176 located at the foot of mast 168. A transparent flexible plastic membrane 178 is stretched between ribs 162 and anchoring ring 160 which is solidly attached to the outer wall of the semi-toroidal rigid structure 155. Mast 168 contains a water feed line that brings water under pressure to ball sprinkler 175. Similar ball sprinklers 177 are also located at the top of hemishperical domes 159.
Because of either camp site geographical location or the fact that a nuclear attack can take place at any time of the year, the outside temperature could very well be below freezing should a case of emergency arise. Washing off the radioactive fallout dust with water is then impossible. Antifreeze, or some salt, could be added to the water to alleviate this problem. However, an alternate back up system should be provided, in the case of most camp sites, with means of removing the dust off all external and ground surfaces, within wall 100 perimeter. Means must also be provided to deposit or trap this radioactive dust in a manner such that its radioactivity presents no danger, until it has decayed below a safe level. Vacuum cleaning means are provided as presented in FIG. 15 by robot vacuum cleaner 200, remotely controlled by radio and monitored to do the following: move in all directions, engage and disengage quick connect/disconnect vacuum tube insert 202 and electrical plugs 204, operate a vacuum cleaning brush and apply it against all surfaces to be cleaned, filter and store the radioactive dust, dump this dust in specially prepared dumping wells; all this without the need of a human operator nearby. The robot, when plugged in, is powered by electrical current brought in by electrical lines 208, connected to the camp power plant and to electrical female plug 203. Electrical lines 208 are connected to connectors 207 attached to electrical conduit 209. When the robot is not electrically connected to the camp power plant, power is supplied by battery 220 used only for the following tasks: to move the robot from one plug-in station to another, to leave and enter buildings, to retract the vacuum tube and electrical line, to bring the robot back for inspection or repair in case of malfunction. When the vacuum system is operating, the battery is constantly being recharged and thus always kept fully charged at all times. The quick connect/disconnect insert 202 is mounted at the end of flexible tube-electrical-conduit assembly 212 which is guided by rollers 214 and 216 into storage space 218 located inside the robot vehicle body. Inside robot 200, revolving drum 222 stores conduit assembly 212 and always maintains a slight tension on the conduit assembly to keep it taut between the robot and the quick connect/disconnect plug, at all times. Drum 222 is actuated by slip roller 211 powered by electrical motor 213. Slip roller 211 applies torque on circular flat tracks 215 mounted on the bottom of drum 222. The length of conduit 212 wound on drum 222 is sufficient to permit brush 206 to reach any and all surfaces, within the camp site, from at least two quick connect/disconnect stations, so that all areas within the boundaries of wall 90 can be swept clean. When the area within the reach of a station has been vacuummed, insert 202 is disconnected and the robot proceeds to the next station where insert 202 is then connected. The connecting and disconnecting actions of insert 202 are accomplished by means of the robot motion in the case of wall plugs. Ground plugs are reached by a monitored vertical motion of insert 202, as described later. All ground areas within wall 90 boundaries are flat and without steps or surface irregularities that could immobilize the robot or make it difficult to be swept. Several robots are available and can be used simultaneously in one camp site.
FIG. 15 schematically describes how robot vehicle 201 is supported and propelled: by means comprising three casters that support a large part of the vehicle weight. One single driving wheel 232 supports the balance of vehicle 201 weight and is used for steering the robot. Details of driving wheel 232 actuation, presented in FIGS. 17 and 18, include steering motor 234, driving motor 236 mounted on frame 238, rotatable wheel bracket 240 that contains wheel 232 and guides wheel assembly 242. This assembly comprises two circular flanges 244 maintained by and sliding on two flat surfaces 246 located inside bracket 240, a bevel gear 248 driven by bevel gear 250 powered by motor 236, and wheel axle 252 which can rotate with respect to frame 238. The whole assembly of the driving wheel, its driving motor, its vertically guiding flanges and frame 238 are free to move up and down, relative to bracket 240, within the range of vertical motion allowed by slots 254 located on each face of bracket 240. A set of support springs 256 located between frame 238 and horizontal flange 258 solidly attached to the top of bracket 240, provides the balance of the support for vehicle 201 weight, as earlier mentioned. The springs and the vertically allowed motion of wheel assembly 242 insure that positive contact always exists between driving wheel 232 and the ground. Bevel gears 260 transmit the steering torque to the driving wheel, between motor 234 and bracket 240. The total force reacted by the ground on driving and steering wheel 232 through springs 256 is directly transmitted to vehicle frame 201 by means of sliding pads 262 that are in contact with flange 258. Position feedback is provided within motor 234 so that the operator knows the driving wheel angular position at all times. Bracket 240 can rotate 360 degrees and electrical power must be provided to motor 236 for any and all steering wheel angular positions, and for any and all vertical positions of motor 236. This is achieved by means of sliding electrical contacts 264 and 266 that include circular collecting rings 268 and 270 embedded in the top surface of flange 258, on which spring brushes 272 and 274 contained inside box 275 can slide. Spring brushes 272 and 274 are connected to electrical leads 277, themselves connected to main electrical line 279 of FIG. 17. Flexible electrical conduit 281 supplies power to motor 236. Arrows f and f' indicate directions.
The commands sent to the vacuum cleaner are all radioed in and received through antenna 205' mounted on radio receiver 207 box, attached to vehicle 201. One of these command signals is for the operation of cleaning brush 206 which must be applied squarely against any surface to be cleaned, be it flat or curved. Brush 206 is pushed against such surfaces as 231 and 233 by articulated arm 235 connected to arm 237 through cylindrical joint 239. Arm 237 is articulated at the top and center of vehicle 201, on cylindrical joint 241. The end of articulated arm 235 holds cleaning brush 206 body by means of articulated cylindrical joint 243. Tension springs 242 and 244 are identical and insure that the rest position the cleaning brush body is perpendicular to arm 235, whenever the brush is not pushed against a solid surface. Any force applied against such a surface, as in the direction of arrow f, forces the brush to tilt so that lips 221 and 223 rest on that surface, flat or curved. The sides of cleaning brush 206 are almost solidly covered with bristles 225. Together with lips 221 and 223, they form a quasi closed box 227, with the surface to be cleaned providing the other side of the box. This creates the suction effect needed to suck the dust set loose by the bristles. As the brush moves around, air and dust move in the directions of arrows f 1 and f 2 shown in FIG. 16. Both arms 235 and 237 are hollow tubes, connected through articulations 239, 241 and 243 in such a way that air passage is continuously maintained between collection box 229 and hollow central suction axis 239. The air and dust sucked in enter collection box 229 through a plurality of holes 237, and from there, travel to central axis 239. From central axis 239, the air-dust mixture exits at the bottom of duct 239 into collection chamber 219, from which it is led by duct 245 (connection shown by letters "a" in FIG. 15) into dust receptacle 247 mounted around vehicle 201 body, with its low point located at 249 in FIG. 20. The air is filtered by flexible filtering membrane 251 attached to the bottom and top of receptacle 247 and retained structurally by rigid screen 253, also affixed to the bottom and top of receptacle 247. The filtered clean air then passes into volume 255 from which it exits through duct 257 into a slip sealed collector 259 attached to vehicle 201 structure. The air leaves the annular chamber of collector 259 through opening 261 which lets the air into the end of duct 212 which is attached to pipe winding drum 222. The air travels the length of wound duct 212 to exit at point "c" where the wound part of duct 212 ends, then proceeds to the quick connect/disconnect insert 202. A network of vacuum ducts, with a plurality of quick connect/disconnect female receptacles 205 located in the building foundation and on the ground, as shown in FIGS. 1 and 22, is built-in throughout the camp. The quick connect/disconnect female plugs installed in the ground and other duct openings are covered by caps 263 when not in use or when no use is anticipated soon. In the building foundations, the quick connect/disconnect female receptacles communicate with the vacuum duct network through connection tubes 267. The vacuum network is connected to an air suction station located underground as shown in FIG. 29. Electrical line 131 which connects to the camp power plant by means of the electrical contacts on insert 202, is structurally part of flexible air duct 212, along the whole length of duct 212, up to the other end, at air pipe connection 261. At that point, the electrical line is connected to contact rings 189 on which electrical brushes, as shown in FIG. 19, can slide to maintain contact. The camp power plant electrical current is processed by switch-converter 192 to keep battery 220 always fully charged. All electrical motors, solenoids and actuators used for the operation of the vacuum cleaning robot and its equipment are powered by DC current supplied at the battery voltage, from the battery or directly by bypassing the battery, as the case demands.
The radioactive dust 289 collected in chamber 271 must be disposed of quickly, It can be dumped within the complex in a plurality of very deep wells 273 shown in FIG. 23 and located as far away from the buildings as possible, as indicated in FIG. 1. These dump wells, lined with concrete, contain in permanence a non-freezing liquid 282 of density lower than that of water and which can cover dumped dust 283, when in use. A shielding plug 284 always cover these wells. When no use of the wells is contemplated, access holes 285 are covered with a cap such as 263 of FIG. 22. Access hole 285 is used to introduce dump tube 286 to drop the radioactive dust 283. Dump tube 286 is located at the bottom of a collecting tube 287 actuated vertically by actuator 288 mounted on the side of dust receptacle 247 and where low point 249 of that dust receptacle is located. When volume 269 is deemed full enough, the vacuum cleaning robot positions dump tube 286 over a hole 285. A signal is sent through electrical line 289 to actuator 288 to lower dump tube 286. The collecting tube slides downward until stop 290 reaches spout 291 edge. Then hole 292 on side of collecting tube 287 registers with the spout opening. Several vibrators 293 are activated through electrical lines 294 to facilitate the evacuation of the radioactive dust 283 into spout 291. When the dumping operation is completed, collecting tube 287 is retracted and the vacuum cleaning operation can be resumed. The opening of spout 291 is then closed by the external surface of collecting tube 287, and sealed.
Referring to FIG. 15 again, the sweeping motion of cleaning brush 206 is always performed by means of a sideway movement as indicated by arrow f 3 of FIG. 16. The mechanism used to impose this motion onto brush 206 comprises an electrical motor 111 for rotating central axis 239 by means of bevel gears 109 and 113, two compression spring actuators that always tend to cancel the builtin jackknifing action of tubes 235 and 237, electrical actuator 116 powered through lines 117 and connected to ball joint articulation 118 at the end of lever arm 119. The other end of actuator 116 is attached to vehicle 201 structure by articulation 121 to allow some swinging motion up and down of actuator 116 as required. Lever arms 123' and 125 are solidly connected to arms 235 and 237 respectively, whereas arm lever 127 is free to rotate with respect to arms 235 and 237 so that both compression springs in actuators 114 and 115 exert about the same push to open up the angle made by arms 235 and 237.
The radioactive dust is not the only material that a vacuum cleaning system would pick up. The total amount of dust and extra material to be disposed of may be too bulky or too radioactive for the use of only wells as dumping sites. It might be advantageous and simpler to duct most of the debris outside of peripheral wall 90, far away from the camp, specially in case of heavy fallout. FIGS. 24 to 30-B illustrate an approach that includes a plurality of main ducts 161 connected to a dust distribution array 163 of perforated radial tubes 165 connected to perforated circular tubes 167, all buried inside a sand mound 169 located above elevated ground pad 171, so that rain water can drain off. The side of mound 169 facing the camp site is covered with compacted dirt 173 so that very little radioactive dust is trapped inside this dirt. It can then acts as an additional radioation shield. The camp site is located in the direction of arrow f of FIG. 25 and angle A encompasses the view of the camp as seen from the center of mound 169. The perforation holes 179 are located on the bottom half of the distribution tubes 165 and 167 as shown in FIGS. 27 and 28, so that they cannot be plugged by ice. Holes 179 let the air and the dust leak downward so that the length of the air escape route is maximized. The interior volume of mound 169 is filled with loose fine gravel 181 to keep sand 183 from clogging holes 179 or from getting inside tubes 165 and 167 when the system is not used. In this system, the dust filtering, storing and dumping means of the vacuum cleaning robot are not used. Referring to FIG. 15, the end of central axis 239 is connected to slip sealed collecting annular chamber 261, because duct 245 is almost directly connected to the end of duct 212 on drum 222. Such a vacuum system is less prone to clogging and can be used uninterruptedly, saving time and thereby reducing the total exposure by the camp occupants to radiations. The air vacuum and pumping station is shown in FIG. 29. It comprises a multivaned compressor 185 powered by motor 187 connected to electrical lines 188. Motor 187 is supported through vertical shaft 193 by braces 189 and 191 attached to air pump housing 195. The air-dust mixture comes in through duct 194 and leaves through duct 196 that connects to main ducts 161. A coarse filtering station (not shown), located between the camp and mounds 169 and underground, is used to stop the bulky debris, to keep tube 165 and 167 perforated holes from becoming clogged when the system is in use. A sprinkling system (not shown) located above the mounds is used to either keep the sand wet, when the system is used, or to melt ice that may have accumulated, under cold weather conditions on top of the mound, prior to starting the vacuum system, when an emergency situation has developed.
FIGS. 30-A and 30-B show a quick connection assembly that comprises male plug 202 and female plug 31, both shown ready to engage, as soon as male plug 202 is lowered in the direction of arrow f. The assembly of FIGS. 30-A and 30-B corresponds to a ground installed plug, a wall installed plug would be rotated 90 degrees as shown in FIG. 21. The position of the plug assembly (horizontal or vertical axis) does not affect its operation, all plugs are identical. The female plug includes a poppet valve, terminated by a conical tip 35 that can engage and match its counterpart: female conical cavity 37 located at the end of male plug insert 202. Poppet valve 33 rests on seat 39 of body 41 of female plug assembly 31. A seal 43, embedded in seat 39, provides air tightness and prevents water from entering the vacuum system. Poppet valve 33 is kept in the closed position by compression spring 45 located around stem 47 and its guide 49. When male plug 202 is moved against the poppet valve, matching conical surfaces 35 and 37 insure that both parts of the plug assembly, male and female, are centered with respect to each other. A chamfer 81, on the tip of male plug 202, also facilitates the engagement. When the engagement is completed, the inside of hose 212 then communicates with chamber 51 inside female plug body 41, through a plurality of holes 85, located near the tip and on the wall of male plug 202. The air is then ducted from chamber 51 by underground ducts 53 to the main vacuum duct 194. Seal 83 is then in contact with the flat face of the female plug assembly, at ground level, to prevent the introduction of extraneous air or water in the vacuum system. The poppet valve can travel a distance h 1 , larger than the length h 2 of male plug 202.
FIG. 31 shows in more detail the engagement of the quick connect/disconnect plug assembly. Because spring 45 must be strong enough, in its extended position (poppet valve closed), to counteract the force exerted by the pressure differential across the poppet valve, as applied on the area determined by seal 43 contact on the poppet valve conical surface, when engaged, male plug 202 must counteract an even larger force to maintain the engagement. To that effect, a positive locking mechanism 55 comprising a plurality of locking pins 57, leaf springs 59 actuated by push pins 87, are mounted inside male plug 202 bore by means of screws 89. As movable flange 91 slides on the external surface of male plug 202, from contact 101 with main fixed flange 103 to contact 105 against collar stop 107, push pin 87 is forced to leave recess 94 and is pushed in, or let out when sliding flange 91 is pushed back down, which moves locking pins 55 in and out of their locking positions. As male plug 202 becomes fully engaged into female plug 31, electrical contacts are also established by means of conducting rings 127 and 129 connected to electrical lines 131 that lead to the vacuum cleaning robot, as earlier described. Rings 127 and 129 are electrically insulated from male plug 202 wall material. Two spring loaded electrical brushes 133 and 135 make contacts with rings 127 and 129 when male plug 202 is engaged. When flange 103 is lowered, it pushes stem 137 of switch 139, which then establishes contact between brushes 133 and 135, and live electrical line 141 that is connected to the camp power source. The vacuum cleaning robot then switches from battery operation to camp power operation.
Referring to FIGS. 32, 33-A and 33-B, shown are the actuating means for lowering male plug 202, which comprise an actuator 143 mounted on robot frame 201, a guiding fork 151 that extends outward from flange 91 holder 95, a locking pin 96 actuated by solenoid 153 mounted on the side of fork 151. In the case of a horizontally positioned plug assembly, as shown in FIGS. 33-A and 33-B, actuator 143 is not needed, because vehicle 200 is used to push and pull male plug 202 in and out of engagement. To pull male plug 202 out, solenoid 153 is energized, locking pin 96 moves in between flanges 91 and 103 in the U-shaped circular groove 73, which gives a positive grasp to fork 151 on male plug 202 assembly. In the configuration of FIG. 32, when plug 202 is away from the robot vehicle, air duct 212 is free to pull away from fork 151 to assume a more compliant shape such as 182, so that minimal side forces are exerted on male plug 202, when engaged. In the configuration of FIG. 33-A, roller 214 and guide 184 assembly insure that air duct 212 is always within the guidance of fork 151. Referring back to FIG. 15, which corresponds to the configuration of FIGS. 33-A and 33-B, roller 214 is fixed, but roller 216 can move up and down as shown by arrow f 1 in a manner such that its motion is coordinated with the rotational movement of drum 222, so that the winding of air pipe 212 is accomplished in an orderly fashion. The mechanism used to move roller 216 vertically and coordinate its motion with that of drum 222 is not shown, being well known in the art. If the configuration of FIG. 32 is used, roller 216 moving mechanism is equipped with a guide 186, located where air tube 212 makes its 90-degree turn, thereby playing a role similar to that filled by guide 184 of FIG. 33-A.
Referring to FIGS. 34-A and 34-B, air connection and arm articulation 239 is depicted as comprising rigid air ducts (or arms) 235 and 237 that are connected by a rotatable joint that includes a hollow hub 60 located inside rotating cylinder 61, both being held together by flanges 62 and 63, which are retained by central rod 64. Seals 65 and 66 keep air leakage from the outside to a minimum. Flanges 62 and 63 support arm lever 127 that connects to spring actuators 114 and 115 of FIG. 15 by means of articulation 67 located at the free end of arm lever 127. The air connection is achieved by means of holes 73 in the wall of hollow hub 60 that open into chambers 75 inside cylinder 61 wall, and which communicate with channel 77 which is opened to the inside of rigid duct 235. A total angular motion of at least 120 degrees of arms 235 and 237 is provided by the cuts 79 in cylinder 61 to give clearance to air duct 237. The angular "length" of chambers 75 insures that the air passages are kept open for a third of a full turn.
DISCUSSION AND OPERATION OF THE INVENTION
The phenomenology of a nuclear explosion above ground level can be simply summed up as follows:
1. During a very brief period of time (microseconds), initial radiations and thermal energy are released. The energy release manifests itself in the form of light and heat. Heat, in the atmosphere, generates a shock wave. The intense light emitted may cause additional secondary sources of heat, far away from the fireball created by the initial radiations;
2. If the fireball reaches the ground, earth particles are set loose, irradiated, mixed with fission or fusion by-products and carried upward in the column of hot air as debris. These debris will eventually fall back on earth, mostly at a distant location in the form of fallout;
3. If the nuclear weapon is detonated at high altitude, the electro-magnetic pulse generated by the interaction of the initial radiation particles with the surrounding ionized gas then can generate lasting disturbances in the propagation of other man-made electro-magnetic waves. At close range, the electromagnetic pulse can cause high voltage burts in conducting materials; and
4. At considerable distances (several miles) from the detonation point, at ground level, only three of the effects above are of primordial practical interest to potential survivors: the light, the shock wave and the fallout. The first effect provides the means to determine accurately the location and altitude of the detonation point. The second effect (at a known distance, at ground level) provides the means to determine the yield of the exploded weapon. From the type of radiations measured and their intensity, to some degree, the ratio of fission to fusion of the weapon can be estimated soon after.
To understand the practical importance and significance of the statements made in 4. above, some basic knowledge of the first effect that will determine the chance of survivability of people, at distances where people can easily survive, if adequately sheltered, must be established first. The table below gives the values of the physical parameters of interest for this discussion, as a function of weapon yield and distance. The symbols used later in the text are defined in that table for ease of understanding.
______________________________________PARAMETERS DISTANCE FROM EXPLOSION (miles)OF INTEREST 1.2 3.25 6 16 24 45 65______________________________________Weapon Yield (W) 1 20 1 20 1 20 20in megatonsPeak Over- 30 30 1.7 1.7 .46 .61 .46pressure (P)in lbs/in.sub.2 (psi)Front Wave Veloc- 1950 1950 1150 1150 1050 1060 1050ity (V) in ft/secWind Velocity (U) 1000 1000 73 73 23 28 23in ft/secTime of Arrival of 1.76 4.8 22.7 61.5 101 198.5 273.5Shock Front (t.sub.1)in secondsDuration of Positive .69 1.88 3.53 9.58 4.4 12.25 12.65Phase of the ShockWave (Δt) in sec______________________________________
One cannot help notice that some of the physical parameters listed above have the same values for different values of distances and weapon yields. At this juncture, one should be made aware that this is because the corresponding values of the "dimensionless" parameter D/W.sup.(1/3) are actually identical. Therefore, distance has a vital influence. Two typical weapon yields are selected: 1 and 20 MT (megaton); which represent the practical range of weapons that could most likely be used in a potential attack on most targets. The distances chosen are established to obtain the same values of the static shock wave peak overpressure, for meaningful comparison, also for the reason that strucutural resistance to blast effects is the prime practical consideration for intitial survivability criterion. Blast effects can be identified by a chronological series of events as follows:
1. After a time t 1 from the weapon detonation moment, at a given distance D (from ground zero), the shock wave front arrives (P max of FIG. 35). If unhindered by nearby obstacles, the static pressure in that front is felt as a sudden, instantaneous rise in pressure above ambient pressure;
2. Either as time passes (fixed location), or as one would measure pressure along the depth of the shock wave (fixed time), the pressure inside the shock wave drops rapidly as shown in the curve of FIG. 35. It reaches ambient atmospheric pressure (end of the positive phase) and then decreases below that value to start the negative phase, during which the pressure felt is lower than ambient, until time t 2 , when ambient pressure is finally restored;
3. The shock wave moves at a velocity V and, behind the front, air masses move at a lower velocity U, in the form of a "wind";
4. If stopped by an obstacle on its path, the air mass behind the front "piles up" against that obstacle and a higher pressure is then applied on that obstacle (dynamic pressure); and
5. The air mass has momentum (or exerts pressure for a given period of time on the obstacle surface) and an impulse is delivered to such obstacle surface.
The end result for such obstacle is that of receiving an impulse (or shock), then that of being engulfed in a pressurizing atmosphere, then in a rarefied atmosphere, then that of being exposed to a high velocity wind, if one assumes that the dimensions of the obstacle are small, as compared to the depth of the shock wave. Practically, at distances where structural survivability can effectively be attempted, this is always the case for the size of weapons being considered. For instance, in the case of a 1-MT detonation 6 miles away, the positive phase of the shock wave has a depth of almost 4,000 ft. That distance is of course much larger than any structure dimension of interest. Furthermore, it is obvious that any man-made "obstacle" would have dimensions much smaller than 4,000 ft. Also, a loading duration of possibly a few seconds applied on such structure is more of the nature of a static type of loading than that of a shock loading. For these reasons, man-made structures must be calculated, designed and constructed to withstand external pressures which are to be considered as long duration loads, but applied only in one direction: from the outside inward.
There are two basic approaches to building such structures: rigid enough to withstand the load without failure or flexible and deformable to give in without rupturing and then bounce back also without permanent failure. Both approaches are used in the invention. Economic considerations impose another constraint which is that the cost of construction should not exceed the cost of a standard type one-story residential building, per unit of habitable area, if the structure is intended to provide useful continuous shelter under non-emergency conditions. The rigid strong structure-type buildings are illustrated in FIGS. 1, 2, 3, 4, 5 and 21. The flexible and deformable type of structure is illustrated in FIGS. 11, 12, 13 and 14. Both types can be most advantageously combined to render the overall building complex more attractive and habitable, to provide more space, more light and an impression of outdoor living, while being isolated nevertheless from a hostile and unhealthy environment. A choice must be made of the value of peak overpressure that an affordable construction can successfully withstand if structure designs such as those shown in FIGS. 2, 4, 5 and 21 are used. A value of 2 psi for P max is practical and realistic. The locations of the likely targets for attack by nuclear weapons are well known throughout the nation. The maximum yield that can be realistically anticipated is 20 to 25 MT. The worst combination of values of the applicable factors indicates that the following criteria are realistic and can be used as design guidelines:
1. A distance of at least 15 miles from all ground zeros that correspond to any likely targets in any direction around;
2. A time of arrival of the shock wave of 1 minute; and
3. A duration of the overpressure pulse of 9 seconds.
At this juncture, it should be pointed out that conventional wood frame, one-story residential structures may be partly destroyed by a peak overpressure of 0.5 psi, present dangers (flying broken pieces of glass) as shelter and become practically unhabitable afterward if the explosion generates fallout. The value of 0.5 psi corresponds to a distance (straight line) of 60 miles, encompassing an area 16 times larger than the area delineated by a 15-mile radius; with the difference that, with shelter provided as per the present invention, all people sheltered survive, even in case of fallout, and that few people escape uninjured if not sheltered (and even fewer would survive if there were some fallout). A second point to be made pertains to the use that can be made of such structures and facilities, when they are not used in their primary role of nuclear shelters. Because it is hoped that the need for their use in their primary role will never materialize, a secondary usage is very desirable and economically mandatory.
If one draws 15-mile radius circles around all likely targets within the continental US, one quickly realizes that most centers with heavy population concentrations are enclosed within the areas covered by such circles. This means that the locations of such camp sites are in rural areas with low density population. Because such camp sites and the structures and facilities therein must provide its occupants with all that which is needed for existence under healthy conditions for at least two or three weeks in case of fallout, the camp, its facilities and resources can be used, under non-emergency conditions, as a vacation resort, retreat or the like.
The other design and construction requirement for the structures and the camp is dictated by a threat which is, in most cases very unlikely, in a few other instances very likely, spatially impossible to predict, but more lethal than the blast, should it materialize. That threat is the radioactive exposure caused by fallout debris. The two dependent aspects of fallout are: (1) its likelyhood, before and after the fact; and (2) its predictability, after the fact, of the amount of fallout, in terms of radiation levels, if detection and calculation means are available and if wind velocities and directions are known at the time of the attack. The "fact" refers to a nuclear weapon detonation having taken place. As was mentioned earlier, when the fireball does not reach the ground, no short term fallout is generated. When the fireball touches the ground, depending upon the altitude of the detonation point (above ground level), fallout debris are created and will eventually be deposited later, somewhere else, within several hours. For a given weapon yield and the yield ratio of fusion-to-fission of that weapon, the percentage of fallout debris generated (as compared to the maximum amount, 100%, that would have been generated, had that weapon been exploded at ground level) can vary from 0 (fireball not reaching the ground) to 100% (explosion at ground level). The location and nature of the targets being well known to any potential attacker, according to a logical strategy of maximum and most effective destruction, from a military standpoint, the following is the most likely to happen:
1. Hardened military sites (missile silos and submarine bases) are targeted for ground level detonation;
2. Military and industrial installations of significance need not be targeted for ground level detonation, as they would suffer more extensive damages from an altitude detonation, but still low enough for the fireball to reach the ground; and
3. Civilian centers can suffer the maximum amount of damages (in terms of structures, facilities and lives) from a higher altitude detonation, for a given weapon yield, such that the fireball does not reach the ground, from blast effects. The unknown is whether the potential attacker will decide to trade off less material damage for more human lives, which fallout would undoubtedly cause to happen. For the purpose of the present invention, it is assumed that the possibility of a ground detonation always exists, for any target. However, it is of paramount importance to be able to determine how much fallout, if any, will occur once a nuclear weapon has been detonated within the danger range.
To that effect, light and pressure detectors are located in sensor housing 2 of FIGS. 1 and 14. These detectors are activated when a state of emergency is in effect. For that camp location, with respect to the location of all likely targets, the detectors are aimed at such targets and cover the range of possible angular variations that may exist between the predicted ideal detonation location and the actual location (after the fact) when the event took place. The sensed information is constantly monitored and recorded. To eliminate such extraneous light signals as those created by lightnings, reflections of sun rays, etc . . . , such light signals are compared to a typical light signal emitted by a nuclear detonation, and then ignored if non-conforming. A light signal which meets the typical light signal model from a nuclear detonation, then triggers the start of all camp emergency operations and procedures already programmed to handle the sequence of impending phenomena from which protection is to be provided to the camp occupants. First, the countdown is started to measure time, starting with the event occurence (t=0); second, calculations are initiated to determine the exact spatial location of the detonation; third, the shock wave characteristics are recorded, including time of arrival from time zero; fourth, the weapon yield is calculated; fifth, wind directions and velocities at various altitudes are entered into the computer (those that were known most recently before the detonation); sixth, the computer calculates the amount of fallout debris likely to have been generated; finally, seventh, the computer then calculates the amount and chronological rate of fallout deposition to be expected from that detonation, expressed in radiation levels. The detectors and the computer are still ready to handle signals from any other nuclear detonation and process them.
If fallout is predicted, one must understand and know how to handle fallout. FIG. 36 exhibits a typical curve of radiation levels as a function of time. After time t 1 , all curves representing fallout decay are identical in shape (exponentials), however, especially before R max is reached, the shape of curve R=F(t) depends upon variables such as wind velocity and direction distributions versus altitude, weapon yield and so on, that can affect the rate of settling of the radioactive debris. However, R o , which corresponds to the peak radiation level that the fallout would have reached, had all the fallout dust fallen at the location considered, at the instant the weapon detonated, can be more easily predicted. In any event, the total amount of radiation to which one would be exposed at a time T after the moment of detonation is the integral under curve R=F(t), and which corresponds to the shaded area under that curve. Because of the faster rate of radioactivity decay when R(t) is high, after a while, the rate of increase of that exposure becomes asymptotic to a plateau which represents the total possible maximum amount of radiation exposure that one could receive at that location, under those conditions, if no protection were provided. Until time t, when the first dust particles start reaching the ground, no radioactivity exists at that location. After all fallout has occurred (after time t 1 ) a rule of thumb can be used to simply predict the radiation level at any time later, it is called the "7-10 Rule". It means that the radiation level (or intensity) becomes one tenth of what it was, at any time, at any time later and which is equal to seven times the value of the time elapsed between the instant of detonation and the time at which the measurement was made. For instance, if R=1000 units after four hours from time zero, it will be only 100 units, 24 hours later, or 28 hours from time zero.
FIG. 37 indicates how the location of the point of detonation is determined. Probe 11 mounted on support 12, inside housing 2 of FIG. 1, is articulated on joint 14 so that the axis of cone 23 can be oriented in the direction (line of sight) of the target to be monitored by that probe as shown by arrow f. Within cone 23, a plurality of tubes 16, painted black inside, terminate at the front end 24 of proble 10, where the end of each tube contains a photoelectric cell. Because of the high instantaneous light flux to be sensed, light filters may be located in front of the photoelectric cells. Each cell sends its own signal and all signals are channelled by lead 18 to the monitoring, recording and computing system. The solid angle β, covered by such probe is wide enough to account for the anticipated range of variations in the point of detonation location, for the target monitored by that probe. The signals received by one probe, when plotted as a function of β, as illustrated in FIG. 38, may yield a curve such as that shown by the solid line, whereas, the anticipated ideal curve is that shown in phantom line (Model). The location of φ max (maximum light flux), at an angle β 1 away from the reference location β=0, indicates the the actual location of the detonation point X in the plane of FIG. 37. Since cone 23 is only the projection of a solid cone, as mentioned earlier, another angle β 2 can also be obtained in a plane perpendicular to the plane of FIG. 37 which also passes through the probe centerline. The exact angle of the actual line of sight of the detonation is then spatially known.
The base of cone 23, of diameter Δ, is rather small for each target and, if targets are relatively close, one probe with a wider conical coverage can monitor more than one target. The actual shape of curve φ(x), calculated from the signals received, may vary greatly from the shape of the anticipated model, especially because weather conditions may be very adverse to good light transmission (clouds, fog, rain, snow), which may tend to flatten the curve, because of light diffraction. This is another reason for making Δ much larger than needed under ideal conditions. Hoever, the peak φ max , thereby β 1 (and β 2 ) and point X, should always be identifiable. From time t 1 on, the radiation intensity is monitored and measured to determine the values of R max and the time at which it occurs, in an area located away from the camp occupants, where a small amount of radioactive fallout dust can safely be left undisturbed. Washing off or vacuuming of the fallout dust within the camp cannot be postponed for too long and should be started before R max is reached.
If there is fallout, there are only three ways available to lower and minimize the total exposure of the camp occupants to radiations: (1) Shield the occupants from the source of radiations; (2) Remove most of the radiation source quickly enough and relocate it farther away (which corresponds to creating distance between the source and the occupants); and (3) Wait until the radioactivity level in the region has decayed to a level safe enough to permit the few hours of exposure needed for safe evacuation to a non-polluted area, far away, or until such time when normal living conditions can be resumed in and around the camp. Actually, all three ways are used to the utmost practical degree. Shielding is provided by walls about the camp, by the depth of the dump wells and the amount of dirt 173 or filtering sand mounds 169. Removing the nearby source of radiation is done by either washing the fallout dust off the building roofs and walls, the ground within wall 90 boundaries, or clean vacuuming these surfaces if the ambient temperature do not permit the use of water mixtures with a low freezing point. Waiting is made possible by having an organized camp equipped, staffed and supplied to operate for several weeks, autonomously from the outside world.
If there is no fallout and if the probability of further nuclear attacks no longer exists, the occupants have survived fully unharmed. They remain in the camp, if they so choose, if the probabiltiy of another attack still exists. If there is heavy fallout, means are provided by the present invention to keep the total radiation exposure of the occupants below a harmful level for at least one heavy fallout occurence. Only deep underground shelters could provide better fallout protection in such case.
The curve shown in FIG. 35 represents the variation of pressure above ambient along the depth of the shock wave and the values of pressure and time given previously in the table of characteristics apply only in the case of an ideal air volume where initial pressures are equal ahead of the shock wave and where no part of the shock wave is disturbed. Practically, because the distances traveled by the shock wave are large compared to the detonation altitude and because the shock wave may travel along uneven surfaces (mountains and valleys), the front of the shock wave will be less abrupt and the value of the front peak pressure will also be lower than those depicted in FIG. 35. The combination of these three factors: (1) decrease of atmospheric pressure with altitude; (2) altitude of the detonation point; and (3) nature of the terrain and topography of the region; affect the shape of and prressure values in the frontal part of the shock wave, but certainly by less than a factor of two. The combination of all other uncertainties (weapon yield, camp site altitude and orientation, etc . . . ) can cause errors in prediction of at least that much, therefore, the theoritical curve of FIG. 35 can still be useful and meaningful as a model. Because the overpressure falls off rapidly behind the shock front and structures have a response time which is appreciable with respect to the duration of the overpressure phase, the actual meaningful "static" pressure to which rigid structures would have time to respond (for intance in the local buckling mode) is more like that shown in phantom line in FIG. 35 and is called P actual . This actual pressure, for the practical application described in the present invention, is probably between 70 and 75% of P max . However, the pressure sensors detect P max and P max is used in the calculation of the weapon yield. Curved shells of the shape shown in FIG. 2, with a lateral span of 30 ft, constructed with a shell 6-inch thick and well anchored, as shown in FIG. 21, can withstand external pressures of 2 psi indefinitely. The 6-inch thick shell, as an example, can consist of two stainless steel sheets, 0.032-inch thick, bonded to a core of light plastic rigid foam located between the two steel sheets. Thicker plastic sheets can also be used instead of stainless steel. The advantage of at least the external sheet being of a metallic nature is to provide a Faraday cage protection against any electromagnetic pulse generated by a high altitude detonation of a nuclear weapon, intended or not.
The flexible deformable dome-shaped structure 157 of FIG. 1, has a much lighter weight per unit area and has no rigidity. Therefore, as the pressure builds up externally when the shock wave passes by, the dome caves in because the rigidity provided by the inflated ribs 162 of FIG. 12 can offer no significant resistance to such caving in motion. The dome anchoring ring does not move, but sliding sleeve 166 leaves stop flange 170, bringing down connecting ring 164 with it because it is guided down by mast 168 external surface. The surface of dome 157 consists mostly of transparent plastic sheets or membranes 178, located between flexible inflated ribs 162, and lighter than ribs 162. These membranes move down ahead of ribs 162, being lighter. Their curvature between ribs 162 and the downward motion of sliding sleeve 166, together, cause a decrease of the volume inside and underneath dome 157. An alert is sounded when the weapon detonation flash occurs and all doors connecting the rigid structure buildings to the dome area are closed, after all occupants have left this area and are on the way to their individual units or to other sheltered common areas. In any case, all camp occupants are instructed to be within the confines of rigid structure buildings within one minute from the sounding of an alert. The air within the space under the dome is trapped and the pressure therein increases to match the external pressure exerted on the dome roof, which very quickly is down to a fraction of the shock wave front peak pressure. The sudden rise in pressure inside the dome would not affect any occupant left in the dome area, because the rate of pressure increase there would be infinitely slower than the pressure rise in the shock front. Soon after, the dome roof goes back up and becomes pressurized internally when the underpressure phase of the shock wave passes by. It is likely that any occupant left there would not feel that depressurizing phenomenon. Within a fraction of a minute, the dome roof has resumed its normal shape and position. Sliding sleeve 166 is back to its rest position against stop flange 178 and never goes beyond this point. During the rarefaction period (underpressure phase), the dome roof membranes may bulge between ribs 162, but without stretching the plastic sheets beyond the elastic point of the material. After the shock has passed by, if no other detonation has been detected in the region, the doors connecting the rigid structure buildings to the dome space can be opened again. By then, some indication should be available as to whether some fallout is anticipated from that explosion. If so, all doors opening on the outside and all windows, which had already been closed at the time of the alert automatically, are now locked. All events to the outside are shut and locked. Glass is not used any place in the complex for transparent surfaces. It is too fragile and dangerous. Polycarbonate sheets are used instead. They all are given a slight convex curvature (bulging out) to strengthen them even more.
In case there is any indication that some fallout may occur, either the dust washing or the vacuum cleaning equipments are readied and put in place so that they can be used as soon as fallout starts to materialize. Dump well caps and quick connect/disconnect plug covers (as applicable) are removed. There is at least one, posssibly two hours available for the personnel to remain outside to complete preparations, without danger, before fallout dust starts coming down. As soon as this manifests itself, all camp occupants and personnel, for safety reasons must thereafter be confined indoor. Nobody can be allowed outside for days, possibly for a few weeks, unless a case of extreme emergency justifies it. The total amount of radiation exposure received by anyone going outside is carefully recorded and monitored, to keep the cumulative radiation dosage received by that individual below the minimal danger level. As a rule, after fallout has started, all operations outside the buildings are conducted by remote control. The operation of the vacuum cleaning system is described earlier and need no additional discussion. However, it should be pointed out that the feedback information received by the operators of all remotely controlled equipment is by visual observation only, through either the windows or the transparent plastic sheets of dome 157 of FIG. 13. All parts of the whole complex can be seen either from the windows or through the dome roof. If and when washing off the dust is possible, in addition to the sprinkler system described peviously, mobile water tanks equipped with sprinkling spouts, also operated by remote control, are available to reach those spots not adequately reached by the fixed sprinklers. From inside the buildings, the level of radioactivity is measured and constantly monitored by personnel, to locate these pockets of radioactive dust outside, from the inside.
Vacuum cleaning of the dome roof is not practical and if washing off the dust is not possible (subzero weather), two cleaning means can then be used effectively: (1) tapping flexible sheets 178 and ribs 162 from the inside, mechanically with a vibrator operated from the ground floor level, and (2) jets of compressed air from nozzles located above stop flange 170, to blow the fallout dust further down on the side of dome 157. Means (1) and (2) above can easily be combined. Also, a coating of dust repellent, possibly combined with electrostatic repulsive means, can be applied on the external surface of dome 157 during the safe one-hour period after the weapon detonation. Another method consists of a thin film of plastic coated with a dust repellent which can be laid on top of dome 157 during the one-hour preparation period. In case the radioactive dust is slightly charged electrically, electrostatic repelling means can also be used from inside the dome. The plastic film earlier mentioned can also be covered on the outisde with a sticky coating to which the dust adheres. After a few hours, when most of the dust has settled, this film can be removed mechanically by remote control through means well known in the art of remote control operation. The removed film can then be disposed of in a dump well or outside the camp grounds.
Prior to a nuclear detonation flash being detected, the camp most likely operates with power and utilities provided by a public utility company. However, such public utility company plants would most probably be destroyed by the attack. Means are therefore provided within the camp to shut off all sources of external supplies automatically, as soon as the detonation flash is detected. At the same time, the camp facilities are immediately switched on. In the case of electrical power, the switch is made before that: as soon as the emergency condition has been instituted. This is to prevent the current surge generated by the electromagnetic pulse (if any) from damaging the camp electrical system. For additional safety, other contacts such as telephone lines can also be cut off under emergency conditions, for the same reason. However, the availability and performance of public utility sources are constantly monitored during the switching off period, so that the camp can be switched back on to the public utility services, should it appear to be safe and judicious, after a while.
The means for providing the services and accomodations to the occupants and the personnel of the camp are not described. They are such that all people inside the camp are given the care needed to keep confined people mentally and physically healthy. All activities are programmed and conducted, under such emergency conditions, on a community basis: feeding, exercizing, counselling, etc . . . Everything is done and meant to make a confinement period of up to several weeks as bearable as possible under such circumstances. In addition, programs and activities are scheduled and organized to prepare the camp personnel and occupants to ready themselves for the tasks that await themm outside where survivors who lived through the ordeal, but less fortunate in being able to survive uninjured and unharmed, need help desperately to be able to cope and then in turn to help others.
Because the effects of exposure to radiations on living cells are cumulative, if the total exposure occurred during a short period of their life span, and because a certain amount of total irradiation can be accumulated safely during a lifetime, personnel can accumulate that total dose of radiations, during the ordeal. A total considered safe for healthy adults, under the unusual circumstances created by a nuclear attack, is about 100 rads. Under normal circumstances, such level should not be considered safe however. This means that, in case of extreme emergency, if there is some fallout, some camp personnel can leave the relative shelter of the buildings to go outside to perform some tasks of vital importance and urgency. Also, personnel can take turns to complete such unscheduled assignments, so that the risk is shared by all personnel and thereby minimized for each of its members. All personnel and other camp occupants are required to wear radiation dosage badges, monitored as frequently as deemed necessary by the management. Such precautions are required only in case of appreciable fallout.
The survivability, and its desirability, of a nuclear war are highly controversial and emotional subjects that cannot be discussed here. Too many aspects of any of its many facets can be argued both ways, pro and con, by parties opposing each other but who have the same aim nonetheless: MINIMIZE THE RISK OF SUCH A GLOBAL CATASTROPHY EVER TAKING PLACE. Opinions differ only as to what should be done and how it should be done. That difference of opinion by itself could be enough to cause a war. There is no concensus of opinion, either, as to what the long term consequences of a nuclear war would be. However, if attempting to make it easier for more people to survive, and under better conditions, with the minimum of lasting health hazards, is deemed a desirable and valuable feature of such attempt, the present invention provides the means to make this possible on a scale larger and at a cost lower than would be possible with deep underground shelters or individual suburban shelters.
It is mandatory that people attempt to survive as large size groups, well organized and well prepared. The problems that would face the survivors, especially those who survived under ideal circumstances, are awesome, both in terms of numbers and complexity. As a group, they will have the only chance to optimize their state of readiness before the attack, immediately after the attack and much later, when able survivors are badly needed to help others and make living possible again on earth. The traumas to deal with would not be only of a physical nature, but more importantly, of mental, psychological and social natures. Only people in large groups, well prepared, well organized and well balanced in terms of individual capabilities can have a chance to succeed in being of effective assistance to others, fast enough to be useful. The subjects of financial participation, group organization, management, defense, planned assistance to others, prealert warnings, logistics and storage of supplies, communications with the outside after an attack, etc. . . . , are neither described nor discussed here. They are deemed to be beyond the scope of and are not considered part of the present invention.
The present invention, however, presents the features, means and characteristics that are essential to and required by the implementation of such an attempt at survivability. It is unfortunate that, for the first time in modern history, individuals, on scales never before imaginable, for such a brief period of time, must count only on themselves if they wish to attempt meaningfully to survive the evil of forces unleashed by their officials. Unless and until those individuals who elect to attempt such meaningful survival have at their disposal the means to try, such attempt is hopeless and doomed. The present invention offers the necessary first step in that direction.
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Structures are constructed and arranged on a camp site to provide shelter to evacuees seeking survival, as a GROUP, in case of a nuclear attack on or near their city. The construction, disposition, arrangement and shapes of the structures are such that people inside these structures are not affected by the blast of the nuclear explosion, for peak overpressure levels well above those which conventional structures cannot survive. The structures and the camp site are equipped to provide the elimination of fallout dust in a short time so as to bring the total exposure of the evacuees to radioactivity levels low enough to be safe, until the radioactivity within miles has decayed down to levels acceptable for long time exposure. The sheltering structures are interlinked to provide a quasi normal indoor way of life during the period of necessary confinement of the evacuees, so that no evacuee feels the urge to leave the protection provided within the compound against the surrounding grounds radioactivity. The compound configuration is set up to provide the maximum effectiveness for defense against any marauding gangs, until protection can be secured from the police authorities in charge. The size and the implementation for autonomous survival of the camp site are such that no support from the outside world is required for a period of up to several weeks. The overall camp site set up is also such that peacetime and economical use of the camp facilities and amenities can be made, when it is not utilized as survival camp, which, of course, is the most fervent hope of everyone.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a press section of a papermaking machine and to a pressure shoe for use in a press section having an extended nip.
2. History of the Prior Art
The concept of a stationary shoe exerting pressure on a rotating drum through a moving paper web transport system produced questions of friction, temperature, tension, and materials. These questions became evident when the transport systems developed a performance inhibiting bulge at the nip. In earlier patents entitled, "Extended Nip Press with Special Belt Reinforcement," U.S. Pat. No. 4,229,253, issued to the Applicant on Oct. 21, 1980 and "Extended Nip Press with Bias Ply Reinforced Belt," U.S. Pat. No. 4,229,254, issued to Michael L. Gill on Oct. 21, 1980, transport belt designs were proposed as answers to some of these questions. A reinforced belt was found to bulge less at the extended nip. As a result, the belt tension, machine part wear, and energy consumption could be reduced. Nevertheless, further reduction in power consumption, frictional forces, and pressure concentrations at the nips of the papermaking machine were still needed.
D. D. Fuller, in his text entitled, Theory and Practice of Lubrication for Engineers, published in 1956, studied the friction and pressure buildups on the surface of variously designed hydrodynamic bearings. His studies indicated the design of the inlet geometry for hydrodynamic bearings had little effect on the frictional forces or pressure buildups at the bearing surface. As a result, prior art in the area of extended nip applications in papermaking machinery indicated little need for specialized nip shoe design.
When Fuller's conclusions were tested, it was unexpectedly discovered that nip shoe design is significantly relevant when compliant or compressible materials are subjected to the hydrodynamic bearings. The applicant found that the compliant transport systems used in paper making operations exhibit properties which are appreciably different from the noncompliant surfaces tested by Fuller.
Fuller discussed the friction, pressure, and lubrication considerations associated with shafts, metal sliding surfaces on production machine tools, and the interfaces of other metallic components. Such applications required no special hydrodynamic bearing design to maintain an adequate film of lubrication along the interface of contacting metal parts. However, the bearing design was found to have a substantial impact when used with the compliant felts and transport belts common in papermaking machinery.
Data indicated that the compliant transport systems, used to move a paper web through a papermaking machine, "bunched up" at inrunning nips and caused excessive friction, pressure, and power consumption throughout the papermaking machine. A film of lubricant at the interface of a nip shoe and compliant transport system was consistently wiped away by the friction and pressure concentrations at the inrunning nip.
Faced with this dilemna, the extended nip shoe design was modified and eventually a shoe which significantly reduced friction and pressure at the inrunning nip was developed. The novel extended nip shoe design also maintained a film of lubricant at the interface of the compliant transport system and the extended nip shoe. It was concluded that by extending the nip shoe beyond the point where the compliant transport system initially compacts against the shoe and opposing surface, lubricant could be introduced into, and maintained throughout, the shoe-compliant transport system interface.
The disclosed extended nip shoe design decreases the pressures at the inrunning and outrunning nips. A lubricating film at the shoe-compliant transport system interface decreases the frictional forces along that interface. Since the impediments of friction and pressure concentration are decreased, the power required to move the compliant transport system across the extended nip shoe is also reduced. By-products of the decreased friction, pressure, and power consumption include lower operating costs and extended bearing and compliant transport system lives since less tension is required to move the transport system over the shoe. The invention permits increased control of paper web processing time under selected pressures. The extendability of the nip allows lower pressure application to a web of paper over longer time periods. The web processing operation is extended from the previous line of contact between two press rolls to the longer contact time available with the extended nip. This feature may produce a higher quality of processed paper than previously realized under short time but high pressure paper processing.
SUMMARY OF THE INVENTION
An extended nip shoe for a press section in a papermaking machine compresses a web of paper riding on a compliant transport system along a portion of the press section. This pressure application aids the removal of moisture from the paper.
The extended nip shoe has an apparatus for applying a lubricant to the compliant transport system to decrease the frictional forces between the shoe surface and the compliant transport system. The inrunning nip surface of the shoe is inclined or ramped to gradually apply the compressive force exerted by the shoe onto the compliant transport system. The inclined surface presents a throat leading into the inrunning nip. The throat funnels the lubricant to the compliant transport systemshoe interface in a manner which effectively maintains a layer of lubricant along the entire interface.
The outrunning nip surface is inclined or ramped to gradually release the compressive forces on the compliant transport system. High pressure differences on the processed web of paper are thereby reduced to improve paper quality. The side edges of the shoe also offer pressure relief by sloping or ramping away from the axis of rotation of the press roll. This shoe geometry directs excess lubricant away from the compliant transport system and the web of paper into a lubricant reservoir for subsequent recirculation and application to the transport system at the inrunning nip of the shoe.
The invention may be used with hydrodynamic and hydrostatic bearings to relieve the frictional forces and pressure differences along the inrunning, outrunning, and side edges of the bearings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a side schematic view of the compliant transport system for transporting a web of paper through the shoe-press roll interface;
FIG. 2 is a schematic side view of the shoe-press section interface depicting lubricant being wiped from a shoe not having the extended nip of the invention;
FIG. 3 is a sectional side view of the extended nip shoe in its operating environment;
FIG. 4 illustrates the extended nip shoe;
FIG. 5 represents the load arc of the extended nip shoe on a press roll of a papermaking machine;
FIG. 6 is a sectional side view of a hydrostatic shoe having the extended nip of the invention; and
FIG. 7 is a sectional side view of two hydrodynamic shoes having the extended nip of the invention.
DETAILED DESCRIPTION
A press section 20 in a papermaking machine is depicted in FIG. 1. The purpose of this section is to remove moisture from a web of paper which is being formed. This moisture removal occurs along the interface of a press roll 22 and a nip shoe 24. The web of paper 26 is transported to this interface between an upper felt 28 and a lower felt 30. These felts form continuous loops through the press roll-nip shoe interface.
The felts and web of paper are transported through the press roll-nip shoe interface by a compliant belt 32. This compliant belt is made of a lubricant impermeable material to shield the felts and web of paper from lubricant applied to the compliant belt 32 to decrease friction along the belt-shoe interface.
The web of paper is transported through the press roll-nip shoe interface to primarily remove moisture from the paper web. In addition, the pressure applied by the nip shoe 24 to the web of paper 26 may be used to impress a smooth finish on the paper, remove lumps from stock used in forming the paper, and compress the web of paper to a desired thickness. It is further contemplated that such operations may be performable by constructing an interface between two nip shoes. Such an interface could be extended to a predetermined length to permit paper processing under lower pressures for longer periods of time. Such an arrangement could produce substantial savings due to reduced component wear and energy requirements.
It was found that existing nip shoe designs were inadequate for use with the compliant transport systems common to papermaking machines. These compliant transport systems 34 (FIG. 2), composed of felts and a compliant belt, bulged at the inrunning nip when compressed by the nip shoe 24 against the press roll 22. The bulge impinged upon the inrunning nip surface 36 and wiped off the lubricant intended to decrease the friction between the compliant transport system 34 and the nip shoe 24. The radical compression of the compliant transport system 34 produced high pressure concentrations at the inrunning nip surface 36. Consequently, frictional forces and temperatures were high along the compliant transport system-nip shoe interface. These conditions required more energy to be consumed in moving the compliant transport system. Bearing and material lives decreased because more tension was required on the compliant transport system to remove the undesirable bulge at the inrunning nip. Consequently, the existing shoe design would involve frequent parts replacement, corresponding lost production, and inevitable paper quality deterioration during the marginal operation of a worn compliant transport system.
The invention offers a solution to the above described problems. One objective of the invention was to gradually distribute and apply pressure from the nip shoe 24 (FIG. 3) to the web of paper 26 against a press roll 22. This gradual pressure application would eliminate the problem causing bulge in the compliant belt 32, lower felt 30, and upper felt 28. A second objective of the invention was to maintain a film of lubricant along the interface of the nip shoe 24 and compliant belt 32 to decrease the frictional forces and associated high temperatures.
The extended nip shoe 24 (FIG. 3) performs as a hydrodynamic bearing. A web of paper 26 may be sandwiched between an upper felt 28 and a lower felt 30. In the alternative, paper processing may occur in the absence of an upper felt 28.
A compliant belt 32 contacts lower felt 30 prior to reaching the inrunning nip point 38 formed between the nip shoe 24 and press roll 22. Prior to contacting lower felt 30, compliant belt 32 is lubricated for its passage along the shoe-press roll interface by passing over lubricant reservoir 40. The lubricant is maintained at a level sufficiently high to contact the transport belt 32 as it moves toward nip shoe 24. Flexible side panels 42 (FIG. 4) on reservoir 40 prevent lubricant spillover during lubricant contact with the compliant belt 32 (FIG. 3).
The inrunning nip surface 36 extends from inrunning nip point 38 approximately 2-4 inches (denoted as Z in FIG. 5). Nip shoe 24 (FIG. 3) is advanced toward press roll 22 by a piston cylinder combination 44. The force applied by the combination 44 is transmitted to nip shoe 24 through pivot 46.
When nip shoe 24 exerts pressure against press roll 22, the area under this force forms a load arc 48 (FIG. 5). This load arc extends from the inrunning nip point 38 to the outrunning nip point 50.
Pivot 46 is positioned along nip shoe 24 so the distance from inrunning nip point 38 to pivot 46 (denoted by y) divided by the distance between inrunning nip point 38 and outrunning nip point 50 (denoted by x) yields a quotient of between 0.6 and 0.8. In contrast, hydrodynamic bearings used with noncompliant materials locate the pivot for the bearing at a position where (y/x)=approximately 0.58.
The extended inrunning nip surface 36 gradually applies the force exerted by the shoe 24 to compliant belt 32 (FIG. 3). This gradual force application is accomplished by inclining inrunning nip surface 36 (FIG. 5) approximately 1.5° (denoted by the symbol θ) from a line substantially tangent to the load arc 48 of nip shoe 24 through inrunning nip point 38. By inclining the inrunning nip surface 36 as described, a ramp is provided which is essentially free of abrupt changes. The smooth transition of the compliant belt 32 (FIG. 3), lower felt 30, paper web 26, and upper felt 28 from an uncompressed to a compressed state allows a film of lubricant to remain on the compliant belt 32 throughout the nip shoe 24-compliant belt 32 interface.
Prior to the application of pressure by the nip shoe 24, felts 28 and 30 have a thickness of approximately 0.120" while compliant belt 32 is approximately 0.3" thick. The full force of nip shoe 24 fully compresses compliant belt 32 and felts 28 and 30 at inrunning nip point 38. In the fully compressed state, felts 28 and 30 have thicknesses of approximately 0.07" while compliant belt 32 compresses to 0.290". Such compressions indicate that significant thickness changes occur in the felts. As a result, tests have indicated that the greater the change in thickness, the more inrunning nip surface 36 must be extended beyond inrunning nip point 38. A two-four inch inrunning nip surface 36 has been adequate for uncompressed felt thicknesses of 0.120" and compliant belt 32 thicknesses of 0.3".
Outrunning nip surface 52 (FIG. 3) has a twofold function. First, the outrunning nip surface 52 channels lubricant from the nip shoe-compliant belt interface to a catch pan 54 under nip shoe 24. This lubricant is recirculated to reservoir 40 by pump 56. The second function of outrunning nip surface 52 is to gradually release the compressive force of nip shoe 24 from compliant belt 32, felts 28 and 30, and paper web 26. The length of outrunning nip surface 52 is not as critical as the length for inrunning nip surface 36. However, outrunning nip surface 52 must also be inclined approximately 1.5° (denoted by θ in FIG. 5) from a line substantially tangent to load arc 48 through outrunning nip point 50. This inclination allows the compressive force exerted by nip shoe 24 to be gradually removed.
Referring to FIG. 4, side edges 58 of nip shoe 24 are inclined away from the axis of rotation of press roll 22 (FIG. 3). Compliant belt 32 distorts sideways during the movement along the nip shoe-compliant belt interface. This sideways distortion brings compliant belt 32 to the side edges 58 (FIG. 4) of nip shoe 24. Side edge inclination gradually relieves pressure concentrations on compliant belt 32 (FIG. 3) to avoid adverse crimping, stress, or other quality related considerations in paper processing. In addition, the side edges 58 (FIG. 4) direct excess lubrication away from the compliant belt 32 (FIG. 3) and lower felt 30 to avoid contamination of paper web 26 by lubricant.
Alternative embodiments of the invention are shown in FIGS. 6 and 7. In FIG. 6, a hydrostatic shoe 60 is shown having hydrodynamic inrunning and outrunning nip surfaces 62 and 64, respectively. Hydrostatic shoe 60 exerts compressive forces on compliant belt 32 using lubricant in shoe reservoir 66 maintained under pressure by pump 68. In FIG. 7, two hydrodynamic shoes 70 are used to compress the compliant belt 32, lower felt 30, paper web 26, upper felt 28, and a second compliant belt 72. Reservoirs 40 lubricate the interfaces of the compliant belts 32, 72 and hydrodynamic shoes 70.
The hydrodynamic inrunning nip surface 62 (FIGS. 6,7) has the length and inclination of the previously described nip shoe 24 (FIG. 5). Compliant belt 32 (FIGS. 6,7) contacts the lubricant in reservoir 40 to decrease the frictional force along the compliant belt-hydrodynamic inrunning nip surface. The compliant belt 32, lower felt 30, paper web 26, and upper felt 28 are then fully compressed from inrunning nip point 38 to outrunning nip point 50. Excess lubricant from reservoir 66 (FIG. 6) is channeled along hydrodynamic outrunning nip surface 64 to catch pan 54 for recirculation to shoe reservoir 66 and lubricant reservoir 40. Hydrodynamic outrunning nip surface 64 (FIGS. 6,7) is inclined as outrunning nip surface 52 (FIG. 3) to gradually release the compressive force applied by hydrostatic shoe 60 (FIG. 6) and hydrodynamic shoe 70 (FIG. 7).
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An extended nip shoe for a press section in a papermaking machine distributes a compressive force to an inrunning compliant transport system advancing a web of paper. The shoe introduces and maintains a film of lubricant throughout the extended nip shoe-compliant transport system interface. Similarly, release of the compressive force is gradual to eliminate points of high unit loads on the compliant transport system and paper web.
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BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a solid polyurethane powder coating composition which contains a uretdione group and cures at low baking temperatures, to a process for preparing such composition, and to its use for producing plastics.
[0003] 2. Discussion of the Background
[0004] Externally or internally blocked polyisocyanates which are solid at room temperature constitute valuable crosslinkers for thermally crosslinkable polyurethane (PU) powder coating compositions.
[0005] For example, DE-A 27 35 497 describes PU powder coatings featuring outstanding weathering stability and thermal stability. The crosslinkers whose preparation is described in DE-A 27 12 931 are composed of isophorone diisocyanate which contains isocyanurate groups and is blocked with ε-caprolactam. Also known are polyisocyanates which contain urethane, biuret or urea groups and whose isocyanate groups are likewise blocked.
[0006] The disadvantage of these externally blocked systems lies in the elimination of the blocking agent during the thermal crosslinking reaction. Since the blocking agent may thus be emitted into the environment, it is necessary on environmental and occupational hygiene grounds to take special measures to clean the outgoing air and/or to recover the blocking agent. Moreover, the reactivity of the crosslinkers is low. Curing temperatures above 170° C. are required.
[0007] DE-A 3030539 and DE-A 3030572 describe processes for preparing polyaddition compounds which contain uretdione groups and whose terminal isocyanate groups are irreversibly blocked with monoalcohols or monoamines. A particular disadvantage are the chain-terminating constituents of the crosslinkers, which lead to low network densities in the PU powder coatings and thus to moderate solvent resistances.
[0008] Hydroxyl-terminated polyaddition compounds containing uretdione groups are subject matter of EP 0 669 353. On the basis of their functionality of two they exhibit improved resistance to solvents. A common feature of the powder coating compositions based on these polyisocyanates containing uretdione groups is that they do not emit any volatile compounds in the course of the curing reaction. However, at at least 180° C., the baking temperatures are high.
[0009] The use of amidines as catalysts in PU powder coating compositions is described in EP 803 524. Although these catalysts lead to a reduction in the curing temperature, they exhibit a marked yellowing, which is generally unwanted in the coatings field. The cause of this yellowing is probably the reactive nitrogen atoms in the amidines. These can react with atmospheric oxygen to give N-oxides, which are responsible for the discoloration.
[0010] EP 803 524 also mentions other catalysts which have been used to date for this purpose, but without showing any particular effect on the curing temperature. They include the organometallic catalysts known from polyurethane chemistry, such as dibutyltin dilaurate (DBTL), for example, or else tertiary amines, such as 1,4-diazabicyclo[2.2.2]octane (DABCO), for example.
[0011] WO 00/34355 claims catalysts based on metal acetylacetonates, e.g., zinc acetylacetonate. Such catalysts are in fact able to lower the curing temperature of polyurethane powder coating compositions containing uretdione groups, but as reaction products give primarily allophanates (M. Gedan-Smolka, F. Lehmann, D. Lehmann, “New catalysts for the low temperature curing of uretdione powder coatings” International Waterborne, High solids and Powder Coatings Symposium, New Orleans , Feb. 21-23, 2001). Allophanates are the reaction products of one mole of alcohol and two moles of isocyanate, whereas in the conventional urethane chemistry one mole of alcohol reacts with one mole of isocyanate. Therefore, as the result of the unwanted formation of allophanates, isocyanate groups valuable both technically and economically are destroyed.
SUMMARY OF THE INVENTION
[0012] It is an object of the present invention to provide highly reactive polyurethane powder coating compositions containing uretdione groups which can be cured even at very low temperatures and which are particularly suitable for producing plastics and also for producing high-gloss or matt, light- and weather-stable powder coatings.
[0013] This and other objects have been achieved by the present invention the first embodiment of which includes a highly reactive polyurethane powder coating composition, comprising:
[0014] A) at least one uretdione-containing powder coating hardener based on aliphatic, (cyclo)aliphatic or cycloaliphatic polyisocyanates and hydroxyl-containing compounds, the hardener having a melting point of from 40 to 130° C., a free NCO content of less than 5% by weight, and a uretdione content of 6-18% by weight,
[0015] B) at least one hydroxyl-containing polymer having a melting point of from 40 to 130° C., and an OH number of between 20 and 200 mg KOH/g,
[0016] C) at least one catalyst of the formula
M(OR 1 ) n (OR 2 ) m (OR) o (OR 4 ) p (OR 5 ) q (OR 6 ) r ,
[0017] wherein
[0018] M is a metal in any positive oxidation state which is identical with the sum n+m+o+p+q+r,
[0019] m, o, p, q and r are integers 0 to 6,
[0020] the sum n+m+o+p+q+r=1 to 6,
[0021] the radicals R 1 -R 6 simultaneously or independently of one another are hydrogen or alkyl, aryl, aralkyl, heteroaryl or alkoxyalkyl radicals having 1-8 carbon atoms and the radicals are in each case linear or branched, unbridged or bridged with other radicals, to form monocyclic, bicyclic or tricyclic ring systems and the bridging atoms beside carbon may also be heteroatoms and may additionally have one or more alcohol, amino, ester, keto, thio, urethane, urea or allophanate groups, double bonds, triple bonds or halogen atoms,
[0022] wherein components A) and B) are present in a ratio so that for each hydroxyl group of component B) there is from 0.3 to 1 uretdione group of component A), and
[0023] wherein a fraction of the catalyst under C) is 0.001-3% by weight, based on a total amount of components A) and B).
[0024] In another embodiment, the present invention relates to a process for preparing a highly reactive polyurethane powder coating composition, comprising
[0025] admixing the following components A), B) and C) in a heatable mixer at a temperature of not more than 130° C.;
[0026] wherein
[0027] A) at least one uretdione-containing powder coating hardener based on aliphatic, (cyclo)aliphatic or cycloaliphatic polyisocyanates and hydroxyl-containing compounds, the hardener having a melting point of from 40 to 130° C., a free NCO content of less than 5% by weight, and a uretdione content of 6-18% by weight,
[0028] B) at least one hydroxyl-containing polymer having a melting point of from 40 to 130° C., and an OH number of between 20 and 200 mg KOH/g,
[0029] C) at least one catalyst of the formula
M(OR 1 ) n (OR 2 ) m (OR 3 ) o (OR 4 ) p (OR 5 ) q (OR 6 ) r ,
[0030] wherein
[0031] M is a metal in any positive oxidation state which is identical with the sum n+m+o+p+q+r,
[0032] m, o, p, q and r are integers 0 to 6,
[0033] the sum n+m+o+p+q+r=1 to 6,
[0034] the radicals R 1 -R 6 simultaneously or independently of one another are hydrogen or alkyl, aryl, aralkyl, heteroaryl or alkoxyalkyl radicals having 1-8 carbon atoms and the radicals are in each case linear or branched, unbridged or bridged with other radicals, to form monocyclic, bicyclic or tricyclic ring systems and the bridging atoms beside carbon may also be heteroatoms and may additionally have one or more alcohol, amino, ester, keto, thio, urethane, urea or allophanate groups, double bonds, triple bonds or halogen atoms,
[0035] wherein components A) and B) are present in a ratio so that for each hydroxyl group of component B) there is from 0.3 to 1 uretdione group of component A), and
[0036] wherein a fraction of the catalyst under C) is 0.001-3% by weight based on a total amount of components A) and B).
[0037] In yet another embodiment, the present invention relates to a method of curing a powder coating composition, comprising:
[0038] curing the above powder coating composition at a temperature of not more than 160° C.
[0039] In another embodiment, the present invention relates to a catalyst, comprising:
[0040] a compound of the formula
M(OR 1 ) n (OR 2 ) m (OR 3 ) o (OR 4 ) p (OR 5 ) q (OR 6 ) r ,
[0041] wherein
[0042] M is a metal in any positive oxidation state which is identical with the sum n+m+o+p+q+r,
[0043] m, o, p, q and r are integers 0 to 6,
[0044] the sum n+m+o+p+q+r=1 to 6,
[0045] the radicals R 1 -R 6 simultaneously or independently of one another are hydrogen or alkyl, aryl, aralkyl, heteroaryl or alkoxyalkyl radicals having 1-8 carbon atoms and the radicals are in each case linear or branched, unbridged or bridged with other radicals, to form monocyclic, bicyclic or tricyclic ring systems and the bridging atoms beside carbon may also be heteroatoms and may additionally have one or more alcohol, amino, ester, keto, thio, urethane, urea or allophanate groups, double bonds, triple bonds or halogen atoms.
[0046] The present invention also relates to methods of coating substrates and to coated substrates.
DETAILED DESCRIPTION OF THE INVENTION
[0047] It has surprisingly been found that metal hydroxides and alkoxides accelerate the cleavage of uretdione groups so greatly that when using uretdione-containing powder coating hardeners it is possible to reduce considerably the curing temperature of powder coating compositions.
[0048] The present invention provides a highly reactive polyurethane powder coating composition comprising
[0049] A) at least one uretdione-containing powder coating hardener based on aliphatic, (cyclo)aliphatic or cycloaliphatic polyisocyanates and hydroxyl-containing compounds, the hardener having a melting point of from 40 to 130° C., a free NCO content of less than 5% by weight, and a uretdione content of 6-18% by weight,
[0050] B) at least one hydroxyl-containing polymer having a melting point of from 40 to 130° C., and an OH number of between 20 and 200 mg KOH/g,
[0051] C) at least one catalyst of the formula
M(OR 1 ) n (OR 2 ) m (OR 3 ) o (OR 4 ) p (OR 5 ) q (OR 6 ) r ,
[0052] in which M is a metal in any positive oxidation state which is identical with the sum n+m+o+p+q+r,
[0053] m, o, p, q and r are integers 0-6 and the sum n+m+o+p+q+r=1, to 6, the radicals R 1 -R 6 simultaneously or independently of one another are hydrogen or alkyl, aryl, aralkyl, heteroaryl or alkoxyalkyl radicals having 1-8 carbon atoms and the radicals are in each case linear or branched, unbridged or bridged with other radicals, to form monocyclic, bicyclic or tricyclic ring systems and the bridging atoms beside carbon may also be heteroatoms and may additionally have one or more alcohol, amino, ester, keto, thio, urethane, urea or allophanate groups, double bonds, triple bonds or halogen atoms,
[0054] D) optionally, a reactive compound which is able to react at elevated temperatures with any acid groups that may be present in component B),
[0055] E) optionally, auxiliaries and additives known from powder coating chemistry,
[0056] such that the two components A) and B) are present in a ratio such that for each hydroxyl group of component B) there is from 0.3 to 1 uretdione group of component A), the fraction of the catalyst under C) is 0.001-3% by weight of the total amount of components A) and B), and D) is present where appropriate in a proportion by weight, based on the total formulation, of 0.1 to 10%.
[0057] The melting point of the uretdione-containing powder coating hardener includes all values and subvalues therebetween, especially including 50, 60, 70, 80, 90, 100, 110 and 120° C. The free NCO content of the uretdione-containing powder coating hardener includes all values and subvalues between 0 and less than 5% by weight, especially including 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4 and 4.5% by weight. The uretdione content of the uretdione-containing powder coating hardener includes all values and subvalues therebetween, especially including 8, 10, 12, 14 and 16% by weight. The melting point of the hydroxyl-containing polymer includes all values and subvalues therebetween, especially including 50, 60, 70, 80, 90, 100, 110 and 120° C. The OH number of the hydroxyl-containing polymer includes all values and subvalues therebetween, especially including 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180 and 190 mgKOH/g. The amount of uretdione group for each hydroxyl group includes all values and subvalues therebetween, especially including 0.4, 0.5, 0.6, 0.7, 0.8 and 0.9. The amount of the catalyst C) includes all values and subvalues therebetween, especially including 0.005, 0.01, 0.05, 0.1, 0.5, 1, 1.5, 2 and 2.5% by weight.
[0058] The amount of D) includes all values and subvalues therebetween, especially including 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9 and 9.5% by weight.
[0059] The present invention further provides a process for preparing the powder coating composition.
[0060] The present invention additionally provides for the use of the powder coating compositions of the present invention for producing powder coatings on metal, plastics, glass, wood or leather substrates or other heat-resistant substrates.
[0061] The present invention additionally provides metal coating compositions, especially for automobile bodies, motorbikes and bicycles, construction components, and household appliances, wood coating compositions, glass coating compositions, leather coating compositions, and plastics coating compositions comprising a polyurethane powder coating composition comprising
[0062] A) at least one uretdione-containing powder coating hardener based on aliphatic, (cyclo)aliphatic or cycloaliphatic polyisocyanates and hydroxyl-containing compounds, the hardener having a melting point of from 40 to 130° C., a free NCO content of less than 5% by weight, and a uretdione content of 6-18% by weight,
[0063] B) at least one hydroxyl-containing polymer having a melting point of from 40 to 130° C., and an OH number of between 20 and 200 mg KOH/g,
[0064] C) at least one catalyst of the formula
M(OR 1 ) n (OR 2 ) m (OR 3 ) o (OR 4 ) p (OR 5 ) q (OR 6 ) r ,
[0065] in which M is a metal in any positive oxidation state which is identical with the sum n+m+o+p+q+r,
[0066] m, o, p, q and r are integers 0-6 and the sum n+m+o+p+q+r=1 to 6,
[0067] the radicals R 1 -R 6 simultaneously or independently of one another are hydrogen or alkyl, aryl, aralkyl, heteroaryl or alkoxyalkyl radicals having 1-8 carbon atoms and the radicals are in each case linear or branched, unbridged or bridged with other radicals, to form monocyclic, bicyclic or tricyclic ring systems and the bridging atoms beside carbon may also be heteroatoms and may additionally have one or more alcohol, amino, ester, keto, thio, urethane, urea or allophanate groups, double bonds, triple bonds or halogen atoms,
[0068] such that the two components A) and B) are present in a ratio such that for each hydroxyl group of component B) there is from 0.3 to 1 uretdione group of component A), and the fraction of the catalyst under C) is 0.001-3% by weight of the total amount of components A) and B).
[0069] The melting point of the uretdione-containing powder coating hardener includes all values and subvalues therebetween, especially including 50, 60, 70, 80, 90, 100, 110 and 120° C. The free NCO content of the uretdione-containing powder coating hardener includes all values and subvalues between 0 and less than 5% by weight, especially including 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4 and 4.5% by weight. The uretdione content of the uretdione-containing powder coating hardener includes all values and subvalues therebetween, especially including 8, 10, 12, 14 and 16% by weight. The melting point of the hydroxyl-containing polymer includes all values and subvalues therebetween, especially including 50, 60, 70, 80, 90, 100, 110 and 120° C. The OH number of the hydroxyl-containing polymer includes all values and subvalues therebetween, especially including 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180 and 190 mgKOH/g. The amount of uretdione group for each hydroxyl group includes all values and subvalues therebetween, especially including 0.4, 0.5, 0.6, 0.7, 0.8 and 0.9. The amount of the catalyst C) includes all values and subvalues therebetween, especially including 0.005, 0.01, 0.05, 0.1, 0.5, 1, 1.5, 2 and 2.5% by weight.
[0070] Polyisocyanates containing uretdione groups are well known and are described, for example, in U.S. Pat. No. 4,476,054, U.S. Pat. No. 4,912,210, U.S. Pat. No. 4,929,724 and EP 417 603. A comprehensive overview of industrially relevant processes for dimerizing isocyanates to give uretdiones is given by J. Prakt. Chem. 336 (1994) 185-200. In general, isocyanates are reacted to uretdiones in the presence of soluble dimerization catalysts such as, for example, dialkylaminopyridines, trialkylphosphines, phosphorous triamides or imidazoles. The reaction—conducted optionally in solvents but preferably in their absence—is terminated by adding catalyst poisons when a desired conversion has been reached. Excess monomeric isocyanate is subsequently separated off by short-path evaporation. If the catalyst is volatile enough, the reaction mixture can be freed from the catalyst in the course of the separation of monomer. In this case there is no need to add catalyst poisons. In principle, a broad palette of isocyanates is suitable for the preparation of polyisocyanates containing uretdione groups. In accordance with the present invention, isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), 2-methylpentane diisocyanate (MPDI), 2,2,4-trimethylhexamethylene diisocyanate/2,4,4-trimethylhexamethylene diisocyanate (TMDI), norbornane diisocyanate (NBDI), methylenediphenyl diisocyanate (MDI), and tetramethylxylylene diisocyanate (TMXDI) are used with preference. Very particular preference is given to IPDI and HDI.
[0071] The reaction of these polyisocyanates carrying uretdione groups to give powder coating hardeners A) containing uretdione groups includes the reaction of the free NCO groups with hydroxyl-containing monomers or polymers, such as polyesters, polythioethers, polyethers, polycaprolactams, polyepoxides, polyester-amides, polyurethanes or low molecular mass di-, tri- and/or tetraalcohols as chain extenders and, optionally, monoamines and/or monoalcohols as chain terminators and has already been described on many occasions (EP 669 353, EP 669 354, DE 30 30 572, EP 639 598 or EP 803 524). Preferred powder coating hardeners A) containing uretdione groups have a free NCO content of less than 5% by weight and a uretdione group content of from 6 to 18% by weight (calculated as C 2 N 2 O 2 , molecular weight 84). Polyesters and monomeric dialcohols are preferred. Preferred low-molecular diols are ethyleneglycol, propanediol-(1,2); propanediol-(1,3); 2,2-dimethylpropane-(1,3), butandiol-(1,4), hexanediol-(1,6), 2-methylpentanediol-(1,5), 2,2,4-trimethylhexanediol-(1,6), 2,4,4-trimethylhexanediol-(1,6), heptanediol (1,7), dodecanediol-(1,12), octa-decene-9,10-diol-(1,12), thioglycol, octandecanediol-(1,18), 2,4-dimethyl-2-propylheptane-diol-(1,3), diethyleneglycol, triethyleneglycol, tetraethyleneglycol, trans- and cis-1,4-cyclohexane-dimethanol. Preferred low-molecular triols are glycerin, hexanetriol-(1,2,6), 1,1,1-trimethylol-propane and trimethylol-ethane. A preferred low-molecular tetraol is pentarythrit. Besides the uretdione groups, the powder coating hardeners may also contain isocyanurate, biuret, allophanate, urethane and/or urea structures.
[0072] In the case of the hydroxyl-containing polymers B), preference is given to the use of polyesters, polyethers, polyacrylates, polyurethanes and/or polycarbonates having an OH number of 20-200 (in mg KOH/g). Particular preference is given to using polyesters having an OH number of 30-150, an average molecular weight of 500-6000 g/mol, and a melting point of between 40 and 130° C. Binders of this kind have been described, for example, in EP 669 354 and EP 254 152. It is of course also possible to use mixtures of such polymers. The amount of the hydroxyl-containing polymers B) is chosen such that for each hydroxyl group of component B) there is from 0.3 to 1 uretdione group of component A).
[0073] The present invention also provides for the use of at least one catalyst of the formula M(OR 1 ) n (OR 2 ) m (OR 3 ) o (OR 4 ) p (OR 5 ) q (OR 6 ) r , in which M is a metal in any positive oxidation state which is identical with the sum n+m+o+p+q+r, m, o, p, q and r are integers 0-6 and the sum n+m+o+p+q+r=1 to 6, the radicals R 1 -R 6 simultaneously or independently of one another are hydrogen or alkyl, aryl, aralkyl, heteroaryl or alkoxyalkyl radicals having 1-8 carbon atoms and the radicals are in each case linear or branched, unbridged or bridged with other radicals, to form monocyclic, bicyclic or tricyclic ring systems and the bridging atoms beside carbon may also be heteroatoms and may additionally have one or more alcohol, amino, ester, keto, thio, urethane, urea or allophanate groups, double bonds, triple bonds or halogen atoms, in polyurethane powder coating compositions, and also the catalysts themselves.
[0074] The catalysts C) of the present invention satisfy the formula M(OR 1 ) n (OR 2 ) m (OR 3 ) o (OR 4 ) p (OR 5 ) q (OR 6 ) r , in which M is a metal in any positive oxidation state which is identical with the sum n+m+o+p+q+r, m, o, p, q and r are integers 0-6 and the sum n+m+o+p+q+r=1 to 6. The radicals R 1 -R 6 simultaneously or independently of one another are hydrogen or alkyl, aryl, aralkyl, heteroaryl or alkoxyalkyl radicals having 1-8 carbon atoms and the radicals are in each case linear or branched, unbridged or bridged with other radicals, to form monocyclic, bicyclic or tricyclic ring systems and the bridging atoms beside carbon may also be heteroatoms and may additionally have one or more alcohol, amino, ester, keto, thio, urethane, urea or allophanate groups, double bonds, triple bonds or halogen atoms. Examples of such catalysts are lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, beryllium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, aluminum hydroxide, zinc hydroxide, lithium methoxide, sodium methoxide, potassium methoxide, magnesium methoxide, calcium methoxide, barium methoxide, lithium ethoxide, sodium ethoxide, potassium ethoxide, magnesium ethoxide, calcium ethoxide, barium ethoxide, lithium propoxide, sodium propoxide, potassium propoxide, magnesium propoxide, calcium propoxide, barium propoxide, lithium isopropoxide, sodium isopropoxide, potassium isopropoxide, magnesium isopropoxide, calcium isopropoxide, barium isopropoxide, lithium 1-butoxide, sodium 1-butoxide, potassium 1-butoxide, magnesium 1-butoxide, calcium 1-butoxide, barium 1-butoxide, lithium 2-butoxide, sodium 2-butoxide, potassium 2-butoxide, magnesium 2-butoxide, calcium 2-butoxide, barium 2-butoxide, lithium isobutoxide, sodium isobutoxide, potassium isobutoxide, magnesium isobutoxide, calcium isobutoxide, barium isobutoxide, lithium tert-butoxide, sodium tert-butoxide, potassium tert-butoxide, magnesium tert-butoxide, calcium tert-butoxide, barium tert-butoxide, lithium phenoxide, sodium phenoxide, potassium phenoxide, magnesium phenoxide, calcium phenoxide and barium phenoxide. Mixtures of such catalysts may also be used, of course. They are present in the powder coating composition in an amount of 0.001-3% by weight, preferably 0.01-3% by weight, based on components A) and B). The catalysts may contain water of crystallization, which is not taken into account when calculating the amount of catalyst employed; that is, the amount of water is neglected during the calculation. Particular preference is given to using barium hydroxide and lithium isopropoxide.
[0075] One preferred embodiment of the present invention comprises the polymeric attachment of such catalysts C) to powder coating hardeners A) or hydroxyl-containing polymers B). Thus it is possible, for example, to react free alcohol, thio or amino groups of the ammonium salts with acid, isocyanate or glycidyl groups of the powder coating hardeners A) or hydroxyl-containing polymers B), in order to integrate the catalysts C) into the polymeric system.
[0076] In this context it must be borne in mind that the activity of these catalysts decreases sharply in the presence of acids. The conventional co-reactants of the uretdione-containing powder coating hardeners include hydroxyl-containing polyesters. Because of the way in which polyesters are prepared, they occasionally still carry acid groups to a minor extent. The amount of acid groups in the polyesters should be less than 20 mg KOH/g, since otherwise the catalysts are excessively inhibited. The amount of acid groups in the polyesters includes all values and subvalues between more than 0 and 20 mg, especially including 2, 4, 6, 8, 10, 12, 14, 16 and 18 mg. In the presence of polyesters of this kind which carry acid groups, therefore, it is appropriate either to use the aforementioned catalysts in excess over the acid groups or else to add reactive compounds which are able to scavenge acid groups. Both monofunctional and polyfunctional compounds can be used for this purpose. The possibly crosslinking effect of the polyfunctional compounds, although unwanted owing to the viscosity-increasing effect, is generally not disruptive owing to the low concentration.
[0077] Reactive, acid-scavenging compounds D) are common knowledge in coatings chemistry. For example, epoxy compounds, carbodiimides, hydroxyalkylamides or else 2-oxazolines react with acid groups at elevated temperatures. Suitable examples include Versatic acid glycidyl ester, ethylhexyl glycidyl ether, butyl glycidyl ether, POLYPOX R 16 (pentaerythritol tetraglycidyl ether, produced by UPPC AG), triglycidyl ether isocyanurate (TGIC), EPIKOTE® 828 (diglycidyl ether based on bisphenol A, produced by Shell), and also VESTAGON EP HA 320 (hydroxyalkylamide, produced by Degussa AG), phenylenebisoxazoline, 2-methyl-2-oxazoline, 2-hydroxyethyl-2-oxazoline, 2-hydroxypropyl-2-oxazoline, and 5-hydroxypentyl-2-oxazoline. Mixtures of such substances are of course also suitable. The reactive compound D) is only employed when acid groups are present in the powder coating composition. Where such acid groups are present in the powder coating composition, the reactive component D) is added in a proportion by weight, based on the total formulation, of 0.1 to 10%, preferably 0.5 to 3%. The amount of D) includes all values and subvalues therebetween, especially including 0, 5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, and 9.5% by weight. It is also possible to use catalysts which accelerate this reaction between acid groups and acid scavengers, such as benzyltrimethylammonium chloride, for example.
[0078] For the preparation of powder coating materials it is possible to add the additives E) customary in powder coating technology, such as leveling agents, e.g., polysilicones or acrylates, light stabilizers, e.g., sterically hindered amines, or other auxiliaries, as described, for example, in EP 669 353, in a total amount of from 0.05 to 5% by weight. Fillers and pigments such as titanium dioxide, for example, can be added in an amount of up to 50% by weight of the total composition. The amount of E) includes all values and subvalues therebetween, especially including 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4 and 4.5% by weight. The amount of filler and pigments includes all values and subvalues between 0 and 50% by weight, especially including 5, 10, 15, 20, 25, 30, 35, 40 and 45% by weight.
[0079] Additional catalysts, such as are already known in polyurethane chemistry, may optionally be present. These are primarily organometallic catalysts, such as dibutyltin dilaurate, or else tertiary amines, such as 1,4-diazabicyclo[2.2.2]octane, in amounts of 0.001-1% by weight. The amount of additional catalysts includes all values and subvalues therebetween, especially including 0.005, 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 and 0.9% by weight.
[0080] Conventional uretdione-containing powder coating compositions can be cured only above 180° C. under normal conditions (DBTL catalysis). With the aid of the low-temperature-curing powder coating compositions of the present invention, with cure temperatures of a maximum of 160° C. (lower cure temperatures are entirely possible), it is possible not only to save energy and (cure) time but also to coat a large number of temperature-sensitive substrates which at 180° C. would exhibit unwanted yellowing, decomposition and/or embrittlement phenomena. The cure temperature includes all values and subvalues therebetween, especially including 40, 60, 80, 100, 120 and 140° C. Besides metal, glass, wood, leather, plastics, and MDF boards, certain aluminum substrates are prime candidates. In the case of the latter substrates, an excessive temperature load sometimes leads to an unwanted change in the crystal structure.
[0081] The homogenization of all of the ingredients for preparing a powder coating composition can take place in suitable equipment, such as heatable kneading apparatus, for example, but preferably by extrusion, in the course of which upper temperature limits of 120 to 130° C. ought not to be exceeded. After cooling to room temperature and appropriate comminution, the extruded mass is ground to give the ready-to-spray powder. Application of the ready-to-spray powder to appropriate substrates can be carried out in accordance with the known techniques, such as by electrostatic powder spraying, fluidized-bed sintering, or electrostatic fluid-bed sintering, for example. Following powder application, the coated workpieces are cured by heating at a temperature of from 120 to 160° C. for from 4 to 60 minutes, preferably at from 120 to 160° C. for from 6 to 30 minutes. The curing temperature includes all values and subvalues therebetween, especially including 125, 130, 135, 140, 145, 150, and 155° C. The curing time includes all values and subvalues therebetween, especially including 6, 8, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 45, 50 and 55 minutes.
[0082] Having generally described this invention, a further understanding can be obtained by reference to certain specific examples which are provided herein for purposes of illustration only, and are not intended to be limiting unless otherwise specified.
EXAMPLES
[0083] [0083] Ingredients Product description, manufacturer VESTAGOM BF 1320 Powder coating hardener, from Degussa AG, Coatings & Colorants, uredione content: 13.8%, m.p.: 99-112° C., T g : 87° C. CRYLCOAT 240 OH-polyester, OH number: 24.5; AN: 3.3; from UCB ARALDIT PT 810 Triglycidyl ether isocyanurate (TGIC), from Vantico KRONOS 2160 Titanium dioxide, from Kronos RESIFLOW PV 88 Leveling agent, from Worlee BTAC Benzyltrimethylammonium chloride, from Aldrich BH Barium hydroxide octahydrate WC: 46, from Aldrich LiPA Lithium isopropoxide, from Aldrich DBTL Dibutyl dilaurate, from Crompton Vinyl Additives GmbH
[0084] OH number: consumption in mg of KOH/g of polymer; AN: acid number, consumption in mg of KOH/g of polymer; m.p.: melting point; T g : glass transition point; WC: water content in % by weight.
[0085] General Preparation Instructions for the Powder Coating Materials:
[0086] The comminuted ingredients: powder coating hardener, hydroxy-functional polymers, catalysts, acid scavengers, leveling agents, are intimately mixed in an edge runner mill and then homogenized in an extruder at up to 130° C. maximum. After cooling, the extrudate is fractionated and ground with a pinned-disk mill to a particle size<100 μm. The powder thus prepared is applied to degreased iron panels using an electrostatic powder spraying system at 60 kV, and the coated panels are baked in a forced air dryer.
[0087] Powder coating compositions which were obtained by the above process (amounts in % by weight, except for OHIUD):
VESTAGON CRYLCOAT Examples BF 1320 240 BH LiPA BTAC DBTL OH/UD 1 8.14 48.92 0.44 1.00:0.50 2 11.37 45.52 0.61 1.00:0.75 3 14.18 42.56 0.76 1.00:1.00 4 10.43 46.11 0.46 0.50 1.00:0.75 5 13.07 43.35 0.58 0.50 1.00:1.00 C1* 10.43 46.11 0.50 0.46 1.00;0.75 C2* 13.07 43.35 0.50 0.58 1.00:1.00
[0088] OH/UD: ratio of OH groups to uretdione groups (mol:mol)
[0089] In addition, the following were used in each of the formulations: 40.0% by weight KRONOS 2160, 1.0% by weight RESIFLOW PV 88 and 1.5% by weight ARALDIT PT 810.
[0090] Results of curing at 160° C. after 30 minutes:
Erichsen Ball impact cupping direct Examples [mm] [inch · lb] Remarks 1 >10.0 80 Cured 2 >10.0 110 Cured 3 >10.0 >160 Cured 4 9.5 100 Cured 5 >10.0 100 Cured C1* 0.5 30 not cured C2* 0.5 20 not cured
[0091] Erichsen cupping was measured according to DIN 53 156.
[0092] Ball impact was measured according to ASTM D 2794-93.
[0093] German patent application 10320267.6 filed May 3, 2004, is incorporated herein by reference.
[0094] Numerous modifications and variations on the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.
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Solid polyurethane powder compositions which contain uretdione groups and cure at low baking temperatures, to processes for preparing such compositions, and to their use for producing plastics, especially powder coatings, which crosslink to high-gloss or matt, light- and weather-stable coating films.
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CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is related to non-provisional patent application entitled “Methods for Purifying Gases Having Organic Impurities Using Granulated Porous Glass”, which is being filed herewith and is incorporated by reference.
BACKGROUND
[0002] In some applications involving the use of hydrogen, or gas mixtures containing hydrogen, contamination of the process gas (or gases) can occur due to the presence or generation of organic gases, organic vapors, organic mists, or particulate matter during the particular processing application. And, if the initial, relatively pure, process gas (or gas mixture) is used in large volumes, purification and re-use of this gas may be an economic necessity.
[0003] Although there is an extensive body of literature covering varying methods of purifying gases, many of these methods are often problematic in dealing with relatively high concentrations of organic contaminants in gas streams containing high concentrations of hydrogen. For example, membrane purifiers can easily and rapidly become so contaminated themselves by the removal of organic vapors and oil mists, that they quickly become ineffective. Even the use of pre-filtration (for example, standard types of cartridge filters or activated carbon beds) to protect membrane type purifiers is often not effective for very long when there are high levels of organic mists or high molecular weight oil contamination within the gas(es) so purified. These kinds of pre-filtration/adsorption schemes can sometimes lead to frequent maintenance or complete replacement of the active filtering means and can also sometimes lead to irreparable deterioration in membrane elements if the contamination eventually “breaks through” any of the pre-filtering devices. One proposed solution includes that disclosed by Kidnay, A. J., Hiza, M. J., and Dickson, P. F., “The Kinetics of Adsorption of Methane and nitrogen from hydrogen Gas”, and “Advances in Cryogenic Engineering”, Vol. 14, K. D. Timmerhaus (Editor), plenum Press, NY 1969, pp. 41-48 (hereinafter, Kidnay et al.).
[0004] Another frequently used method of purifying gases, such as hydrogen or helium, involves cryogenic trapping of impurities entrained within these gases. In this kind of process, contaminants are removed by condensation, or adsorption, or by “freezing out” as solids within a low temperature adsorption bed. Often, at least one adsorption bed employed in using this kind of technique involves the use of activated carbon (or activated charcoal, zeolitic molecular sieves, activated alumina, silica gels, and the like, as well as combinations of these conventional adsorbents) in a low temperature adsorption process [Kidnay et al.]. The main problem with this approach is that it is difficult to regenerate conventional packed bed adsorbents that become saturated or nearly saturated with high molecular weight organic impurities. Typically, high temperature steam must be used in these cases, and then an involved process of moisture removal by inert gas purging, at high temperatures, must follow that kind of regeneration step.
[0005] Many adsorbents are used in the field of gas separation, one of which includes silica gel. Silica gel is a granular, highly porous form of silica (SiO 2 ). Generally speaking, it is formed by reaction of a sodium silicate solution with a mineral acid such as HCI or H 2 SO 4 , followed by polymerization of the produced hydrosol. Because of the —OH functional groups, silica gel is a relatively polar material. On the other hand, porous glass is a relatively less polar material in comparison to silica gel.
SUMMARY
[0006] An object of the present invention is to provide a system for purifying gases containing an organic impurity that obviates some of the problems that are associated with more conventional approaches.
[0007] A system for purifying an impure gas includes a source of an impure gas, a purification element operatively associated with the source of impure gas for purifying the impure gas, and a conduit operatively associated with the purification element for receiving a flow of purified impure gas from the purification element and directing the purified impure gas to a container or point of use. The impure gas includes a first gas and an organic compound. The purification element includes a vessel containing a packed bed of granulated porous glass.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] For a further understanding of the nature and objects of the present invention, reference should be made to the following detailed description, taken in conjunction with the accompanying drawings, in which like elements are given the same or analogous reference numbers and wherein:
FIG. 1 illustrates an embodiment of the invention; FIG. 2 illustrates another embodiment of the invention including a purge gas; FIG. 3 illustrates another embodiment of the invention including a purge gas and one configuration of filters; FIG. 4 illustrates another embodiment of the invention including another configuration of a purge gas and filters; FIG. 5 illustrates another embodiment of the invention including two purification elements to allow alternating flows of impure gas and purge gas; FIG. 6 illustrates another embodiment of the invention including two purification elements to allow alternating flows of impure gas and purge gas as well as one configuration of filters; and FIG. 7 illustrates another embodiment of the invention including two purification elements to allow alternating flows of impure gas and purge gas as well as another configuration of filters.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0016] Granulated porous glass has a relatively high adsorption affinity for organic materials in the gaseous state or vapor state and will remove substantially all impurities of this type at relatively low temperatures. Even liquefied organic mists or solid organic particulate material can be trapped by filtration (assisted by adsorption) within a packed bed of granulated porous glass.
[0017] This new method of hydrocarbon removal from gases involves the use of one or more packed beds (filled or partially filled) with granulated porous glass. This material may have several different trade names and may be produced by several different companies. It is understood that the physical properties of various brands of porous glass may vary somewhat from brand to brand. These kinds of property variations can typically be compensated for by adjusting the volume amounts of porous glass that may be used in any particular purification application.
[0018] One of ordinary skill in the art will understand that the patent literature is replete with teachings of packed beds and devices containing them.
[0019] Due to properties of porous glass, it has a relatively high specific surface area due to the presence of pores, voids, micro-cracks, and surface imperfections. Typical BET surface areas of granulated porous glass are about 150 to about 250 m 2 /g, more particularly, either about 150 to about 200 m 2 /g or about 200 to about 250 m 2 /g. Typical average pore radii include about 40 Angstroms to about 3000 Angstroms. More particularly, typical average pore radii include about 40 Angstroms to about 200 Angstroms, about 40 Angstroms to about 60 Angstroms, and about 75 Angstroms to about 3000 Angstroms. Typical non-limiting examples of porous glass compositions include: more than about 94% wt. of SiOH, about 4% wt. to about 6% wt. of B 2 O 3 , and about 0.25% wt. to about 1% wt. of either Na 2 O or K 2 O; more than about 94% wt. of SiOH, less than 6% wt. of B 2 O 3 , and less than about 1% wt. of either Na 2 O or K 2 O with the total wt. %'s of each of the SiOH, B 2 O 3 , and Na 2 O or K 2 O essentially equal about 100; and more than about 94% wt. of SiOH, about 2% wt. to about 6% wt. of B 2 O 3 , and about 0.025% wt. to about 0.25% wt. of either Na 2 O or K 2 O.
[0020] Porous glass may be produced from glass having two phases (one soluble in acid and one insoluble in acid). The soluble phase is leached out of the glass with an acid leaving the insoluble portion behind. U.S. Pat. Nos. 2,106,744, 2,221,709, 2,286,275, and 3,485,687 contain lengthy descriptions of how to prepare porous glass, the contents of which are incorporated by reference. One type of porous glass called controlled porosity glass (CPG) may be obtained from Prime Synthesis, Inc. (2 New Road, Suite 126, Aston, Pa. 19014) under the product name of Native-00500-CPG or Native-01000-CPG. Porous glasses may also be obtained from Corning Inc. (One Riverfront Plaza, Corning, N.Y. 14831) under the product name of Vycor 7930.
[0021] The impure gas which is to be purified contains at least a first gas and an organic impurity. Some non-limiting examples of the first gas include carbon dioxide, oxygen, nitrogen, hydrogen, germane, silane, disilane, trisilane, ammonia, helium, neon, argon, and mixtures of two or more thereof. The method of the invention is especially applicable to impure gases containing at least 10% by volume hydrogen up to less than 100% by volume. Hydrogen may also be present at a relatively higher concentration range such as at least 50% by volume up to less than 100% by volume.
[0022] The organic impurities may be gaseous in form, vaporous in form, mist-like in form, or they may even be in particulate form. While it is believed that the method invention may be used purify gases having non-hydrocarbon impurities, it is especially useful for removing hydrocarbons. Such non-limiting examples of such hydrocarbons include CH 4 , C 2 H 6 , C 3 H 8 , C 4 H 10 , and straight chain alkanes, or cycloalkanes having 5-9 carbon atoms, or straight chain alkanes, or cycloalkanes, or aromatic alkanes having 10-70 carbon atoms.
[0023] Practice of the invention involves flow of an impure gas including a first gas and an organic compound into a packed bed of granulated porous glass. Because of the relatively high adsorption affinity of porous glass for organic materials in the gaseous state or vapor state, the organic compound is preferentially adsorbed thereupon, thereby reducing the concentration of the organic compound in the impure gas and purifying it. The thus-purified impure gas is allowed to flow out of the packed bed.
[0024] Two or more packed beds of porous glass can be used so that one or more packed beds can be “off-line” while undergoing a regeneration process while other packed beds can be “on-line” and actively participating in the purification process. One of ordinary skill in the art will understand that regeneration in this context involves removal of at least some of the organic compound adsorbed on the porous glass thereby increasing its ability to adsorb the organic compound and consequently its ability to purify the impure gas.
[0025] The packed bed(s) may be regenerated with a purge gas. Typical purge gases include oxygen, carbon dioxide, nitrogen, hydrogen, germane, silane, disilane, trisilane, ammonia, helium, neon, argon, and mixtures of two or more thereof.
[0026] In the case of germane, silane, disilane, trisilane, and ammonia, these gases would be used as a purge gas only when they would be compatible with the impure gas to be purified. As one example, ammonia purge gas is particularly appropriate when the impure gas contains ammonia. Another typical purge gas would be the purified impure gas itself. This could be the purified gas exiting another packed bed(s) or from a vessel containing the purified gas. The purge gas may be heated before or during regeneration of the packed bed. Relatively higher temperatures will enhance desorption.
[0027] Preferably, the packed bed is regenerated with an oxygen-containing gas. Typical oxygen-containing gases include air and inert gases slightly enriched with oxygen. By action of the oxygen-containing gas flowing into the packed bed, the organic compound may be oxidized and/or desorbed. In the case of hydrocarbons, oxidation would yield CO 2 and H 2 O. Preferably, enough oxygen in the oxygen-containing gas is allowed to react with the organic compound in order to completely oxidize it. The speed of the oxidation process can be significantly influenced by the concentration of oxygen in the regeneration gas and the temperature conditions that are permitted to exist during the regeneration process. Typically, the temperature of the oxygen-containing gas is at least 100° C.
[0028] One advantage of the invention is that regeneration of the packed bed may be carried out at temperatures higher than that achievable with activated carbon (or other ignitable materials) thereby allowing improved performance in hydrocarbon removal from the packed bed. For instance, temperatures in excess of 450° C. may be used to regenerate the packed bed without causing any significant degradation.
[0029] If necessary, the impure gas stream may be pressurized. The impure gas stream may also be cooled by exchanging heat with a purified gas stream (or by some other cooling means). It is useful to filter the impure gas before it enters the packed bed and/or filter the purified gas after it exits the packed bed. After purification, the purified gas by be stored for later use, immediately re-used as a purge gas, or be used at a point-of-use in a separate process requiring the purified gas.
[0030] As best illustrated by FIG. 1 , one embodiment of the invention includes a purification element 5 containing a packed bed of porous glass and a conduit 9 . An impure gas 1 flows into purification element 5 and the purified gas flows out of the purification element 5 and conduit 9 .
[0031] As best shown by FIG. 2 , another embodiment of the invention includes valves 3 , 11 , 13 , 15 , and conduit 9 . During a purification step, the impure gas 1 flows through open valve 3 and into the purification element 5 while valves 13 , 15 are closed. The purified gas flows through valve 7 and out conduit 9 . During a regeneration step, the purge gas 11 flows through open valve 13 and into purification element 5 , while valve 7 is closed. A mixture of the purge gas and the organic impurity flows through open valve 15 and out conduit 7 , while valve 3 is closed.
[0032] As best depicted in FIG. 3 , another embodiment of the invention includes filters 19 , 21 . During a purification step, the impure gas 1 flows through open valve 3 , filter 19 and into the purification element 5 while valves 13 , 15 are closed. The purified gas flows through filter 21 , valve 7 and out conduit 9 . During a regeneration step, the purge gas 11 flows through open valve 13 , filter 21 and into purification element 5 , while valve 7 is closed. A mixture of the purge gas and the organic impurity flows through filter 19 , open valve 15 and out conduit 7 , while valve 7 is closed.
[0033] As best illustrated in FIG. 4 , another embodiment of the invention includes filters 20 and 22 . During a purification step, the impure gas 1 flows through open valve 3 , filter 20 and into the purification element 5 while valves 13 , 15 are closed. The purified gas flows through filter 22 , valve 7 and out conduit 9 . During a regeneration step, the purge gas 11 flows through open valve 13 , filter 22 and into purification element 5 while valve 7 is closed. A mixture of the purge gas and the organic impurity flows through filter 20 , open valve 15 and out conduit 7 , while valve 3 is closed.
[0034] As best shown in FIG. 5 , another embodiment of the invention includes valves 3 A, 3 B, 15 A, 15 B, 13 A, 13 B, 7 A, and 7 B and conduits 17 A and 17 B. In a first stage, the impure gas 1 flows through open valve 3 A and into purification element 5 A while valves 3 B and 15 A are closed. The purified gas flows through open valve 7 A and out conduit 9 while valves 13 A and 7 B are closed. Contemporaneously with this purification step of the first stage, the purge gas 11 flows through open valve 13 B and into purification element 5 B while valves 13 A and 7 B are closed. The mixture of purge gas and organic impurity flows out of purification element 5 B and through open valve 15 B and conduit 17 B while valve 3 B is closed. In a second stage, valves 3 A, 17 B, 13 A, 13 B, and 17 A are closed and valves 3 B, 7 B, 13 A, and 15 A are opened. The impure gas 1 flows through open valve 3 B and into purification element 5 B while valves 3 A and 15 B are closed. The purified gas flows through open valve 7 B and out conduit 9 while valves 13 B and 7 A are closed. Contemporaneously with this purification step of the second stage, the purge gas 11 flows through open valve 13 A and into purification element 5 A while valves 13 B and 7 A are closed. The mixture of purge gas and organic impurity flows out of purification element 5 A and through open valve 15 A and conduit 17 A while valve 3 A is closed.
[0035] As best depicted in FIG. 6 , another embodiment of the invention includes filters 20 A, 20 B, 22 A, and 22 B. In a first stage, the impure gas 1 flows through open valve 3 A, filter 20 A, and into purification element 5 A while valves 3 B and 15 A are closed. The purified gas flows through open filter 22 A, valve 7 A, and out conduit 9 while valves 13 A and 7 B are closed. Contemporaneously with this purification step of the first stage, the purge gas 11 flows through open valve 13 B, filter 22 B, and into purification element 5 B while valves 13 A and 7 B are closed. The mixture of purge gas and organic impurity flows out of purification element 5 B and through filter 20 B, open valve 15 B and conduit 17 B while valve 3 B is closed. In a second stage, valves 3 A, 17 B, 13 A, 13 B, and 17 A are closed and valves 3 B, 7 B, 13 A, and 15 A are opened. The impure gas 1 flows through open valve 3 B, filter 20 B, and into purification element 5 B while valves 3 A and 15 B are closed. The purified gas flows through filter 22 B, open valve 7 B and out conduit 9 while valves 13 B and 7 A are closed. Contemporaneously with this purification step of the second stage, the purge gas 11 flows through open valve 13 A, filter 22 A, and into purification element 5 A while valves 13 B and 7 A are closed. The mixture of purge gas and organic impurity flows out of purification element 5 A and through filter 20 A, open valve 15 A, and conduit 17 A while valve 3 A is closed.
[0036] Another embodiment of the invention is best illustrated in FIG. 7 . In a first stage, the impure gas I flows through filter 19 , open valve 3 A, and into purification element 5 A while valves 3 B and 15 A are closed. The purified gas flows through open valve 7 A, filter 21 , and out conduit 9 while valves 13 A and 7 B are closed. Contemporaneously with this purification step of the first stage, the purge gas 11 flows through open valve 13 B and into purification element 5 B while valves 13 A and 7 B are closed. The mixture of purge gas and organic impurity flows out of purification element 5 B and through open valve 15 B and conduit 17 B while valve 3 B is closed. In a second stage, valves 3 A, 17 B, 13 A, 13 B, and 17 A are closed and valves 3 B, 7 B, 13 A, and 15 A are opened. The impure gas 1 flows through filter 19 , open valve 3 B and into purification element 5 B while valves 3 A and 15 B are closed. The purified gas flows through open valve 7 B, filter 21 , and out conduit 9 while valves 13 B and 7 A are closed. Contemporaneously with this purification step of the second stage, the purge gas 11 flows through open valve 13 A and into purification element 5 A while valves 13 B and 7 A are closed. The mixture of purge gas and organic impurity flows out of purification element 5 A and through open valve 15 A and conduit 17 A while valve 3 A is closed.
[0037] In each of the embodiments, a heating element may be used to heat the purge gas. Also, a control element may be used to control the opening and closing of the various valves as well as controlling flows of the impure gas and purge gas.
EXAMPLES
[0038] A sample of Corning Vycor Porous Glass (No. 7930) was deliberately contaminated with a source of gaseous hydrocarbons in air and at ambient temperatures until its color changed from clear and grasslike to a yellow/amber color. This material was then heat treated at 450±5° C. in a flowing substantially pure gaseous nitrogen atmosphere for five days. Then, this sample of porous glass was exposed to a flowing gaseous mixture consisting of 20% oxygen/80% nitrogen, at about one atmosphere, and at regeneration temperatures of 450±5° C. for one additional day. These processing conditions eliminated all traces of the organic contamination.
[0039] A subsequent measurement of the BET surface area of this material produced a result of 218 m 2 /g at 77.3° K, indicating no significant alteration in the originally specified surface area of this material. The length of the regeneration test noted above was deliberately extended in order to prove that the effective internal and external surface area of the porous glass would not be compromised by high temperatures or long heating times. In other words, the pore volume and surface area of the crushed or porous glass is not affected by high temperatures that might be used in a regeneration process. Much shorter and similarly effective regeneration times at temperatures at or above 450° C., are also possible.
[0040] The high temperature regeneration process indicated above might not be possible using other type of less inert adsorbent materials. For example, a packed bed containing activated carbon (or charcoal) is very likely to begin burning (internally) under the same temperature and oxygen partial pressure condition, thus completely destroying the packed bed as well as the containment vessel. Other types of adsorbents would be either damaged by these hostile conditions (e.g., silica gel) or their inherent surface areas are very small relative to porous glass (e.g., alumina). In this case, their containment vessels would have to be extremely large in order to allow the same adsorption/absorption capacity as a much smaller containment vessel containing activated porous glass.
[0041] It will be understood that many additional changes in the details, materials, steps, and arrangement of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. Thus, the present invention is not intended to be limited to the specific embodiments in the examples given above and/or the attached drawings.
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Methods and apparatus for purifying gases having organic impurities, including the use of granulated porous glass. A system for purifying an impure gas includes a source of an impure gas, a purification element operatively associated with the source of impure gas for purifying the impure gas, and a conduit operatively associated with the purification element for receiving a flow of purified impure gas from the purification element and directing the purified impure gas to a container or point of use. The impure gas includes a first gas and an organic compound. The purification element includes a vessel containing a packed bed of granulated porous glass.
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This application is a division of copending application Ser. No. 196,807 filed Nov. 8, 1971, which in turn in a continuation-in-part of application Ser. No. 823,164 filed May 8, 1969, now abandoned.
BACKGROUND OF THE INVENTION
This invention relates to a type of controlled release capsules, i.e. capsules with permeable or semi-permeable walls which have the ability to release a solute or a volatile liquid or the like at a predetermined rate. The release of solute is an effect resembling osmosis, while the release of the volatile liquid is an effect produced by partial pressure differences across the capsule walls. An aspect of this invention relates to a process for making the capsules.
There is considerable utility in the art of encapsulation for a means which permits the release of an encapsulated chemical over a predetermined period of time. For example, it is desirable to make one application of agricultural chemicals (fertilizers, pesticides, herbicides, etc.) which is effective for a complete growing season, rather than several successive applications. Also, it is desirable to apply only the necessary amount of fertilizer, thereby preventing ground water pollution.
Various types of coatings (U.S. Pat. No. 3,223,518) and porous packaging films (U.S. Pat. No. 3,059,379) have been suggested for encapsulating solid agricultural chemicals. However, the coatings cannot be utilized to contain aqueous solutions, while the flexible packaging films are not practical for encapsulating liquids. U.S. Pat. No. 2,791,496 discloses the impregnation of exfoliated vermiculite with liquid agricultural chemicals, but this product does not provide a controlled release rate. U.S. Pat. No. 3,423,489 discloses crystalline polyolefin capsules for encapsulating liquids, but these capsules are not suitable for controlled release of the contained liquid.
Accordingly, this invention contemplates providing liquids such as agricultural chemicals in a form which permits release of the chemical over a predetermined period of time. This invention also contemplates a means and method for introducing a controlled amount of microporosity into a membrane which serves as the wall or shell of a capsule.
SUMMARY OF THE INVENTION
This invention provides capsules which have permeable or semi-permeable walls, i.e. walls having microscopic passages or interconnecting pores providing a release route which permits an osmosis-like effect to occur at a controllable or predetermined rate. The observed effect resembles osmosis in that the amount of liquid contained within the capsule walls does not appear to diminish significantly, but any solute dissolved in the encapsulated liquid passes out of the capsules when a moist environment (e.g. soil) containing a lower concentration of solute exists outside the capsules. The capsules also can be used to release liquids volatile at the temperature of use, provided that, a partial pressure driving force is present as in the case when water-containing capsules are placed in a low humidity environment. The capsules are durable, crush resistant, uniformly small, substantially spherical, and non-tacky, and they are particularly suited for providing controlled release of dissolved chemicals from encapsulated aqueous solutions. Among the suitable dissolved chemicals are fertilizers, pesticides, herbicides, and other agents with agricultural utility, but the invention is generally useful for encapsulating liquids or solutions of any desired type. The release rate can be controlled so as to prevent ground water pollution in agricultural applications. The filled capsules are dry and can be readily handled and shipped.
It has been found that a microporous capsule wall can be obtained when certain critical phase relationships are observed during the manufacture of the capsules. The capsule shell- or wall-forming material should comprise at least a first material which melts at elevated or moderately elevated temperatures and is capable of forming a single phase when admixed with a second material (which also melts at elevated or moderately elevated temperatures). A small amount of a high-boiling solvent or plasticizing material can be used, if desired, to facilitate this single phase formation step. After the first and second materials have been blended, heated, and formed into a homogeneous molten phase, the wall forming composition is brought into contact with a fill material (preferably an aqueous liquid) by means of the biliquid column technique disclosed in U.S. Pat. Nos. 3,423,489 and 3,389,194, the disclosures of which are incorporated by reference. Contact with the liquid fill rapidly cools the homogeneous wall-forming phase, and as this molten phase approaces a solidified state and becomes an incipient capsule wall or shell, one of the materials present in this incipient wall begins to separate out as a discontinuous, solid phase dispersed throughout a substantially continuous wall matrix. The resulting dispersed particles are normally considerably smaller than the thickness of the capsule wall which ultimately results. The dispersed particles preferably contract, upon further cooling, at a rate which is faster than the contraction rate of the continuous matrix, but any disparity between the matrix and dispersed phase with regard to their respective rates or degrees of contraction can assist in the formation of cracks or pores in the capsule walls. Since the dispersed phase is present in a significant quantity, e.g. at least 5 parts by weight of the total composition, the resulting capsule is characterized by microporous walls having a porosity (determined by mercury porosimetry) of at least about 3 volume percent. The "microporosity" (this term being used herein to include sub-microscopic porosity) imparts permeability or semi-permeability to the capsule walls, and effects similar to osmosis are observed when a concentration gradient across the capsule wall is present. However, these osmosis-like effects are not necessarily limited to the diffusion of solutes, emulsoids and dispersoids also appear to pass through the capsule walls, indicating a variety of transport mechanisms may be operating. It will be understood, in any event, that this invention is not bound by any theory.
The capsules of the present invention are on the order of about 100 to about 10,000 microns, preferably about 1,000 to about 3,000 microns, in diameter. Capsules of this size are readily packaged, stored, and shipped, while larger capsules are weak, fragile, and subject to breakage during packaging, handling, or shipping. Capsules smaller than 100 microns in diameter have a large shell or wall volume in comparison to liquid fill volume and are excessively expensive for most uses. The capsule shell wall thickness varies from about 0.85 to about 10 microns for a 100 micron capsule diameter, from about 35 to about 400 microns for a 4,000 micron capsule diameter, and from about 85 to about 1,000 microns for a 10,000 micron capsule diameter. These capsule shells provide a volume ratio of contained fill to shell sufficiently high for efficient economical use.
The preferred capsules comprise an aqueous fill and a microporous (including sub-microscopic porosity) capsule wall wherein the capsule wall comprises three or more phases, i.e.: a solid, crystalline olefinic polymer phase, an amorphous phase (e.g. a hydrocarbon resin), and a second crystalline or semi-crystalline phase, e.g. a natural, paraffinic or microcrystalline petroleum wax. In this preferred composition, the wax ordinarily separates out first upon cooling, thus forming a crystalline or semi-crystalline phase dispersed throughout a continuous matrix of the other phases. Microporosity results upon further cooling, due apparently to one or more phenomena, including differences in the rate or degree of contraction between two or more phases and shear forces created by the disparity in structure between the different crystal types or between the polyolefin/amorphous resin and wax phases.
DETAILED DESCRIPTION AND EXAMPLES
As pointed out previously, an important factor contributing to the formation of microporous capsule walls involves differences in rates or extent of contraction of materials used to form the capsule wall or shell. A convenient method has been devised for characterizing the extent of the contraction upon cooling the various materials preferred for use in this invention.. Briefly summarized, the method comprises filling a test tube or equivalent container to a given measured volume with a sample of the material in a molten state. The molten sample is kept in an oven at a standard temperature, e.g. 230° C. (a typical capsule-forming temperature when the biliquid column technique of U.S. Pat. No. 3,423,489 is used), and permitted to equilibrate, so that the melt is at a uniform temperature. Upon equilibration, an excess of sample material, as compared to the original measured volume, will have resulted due to expansion with heat. This excess is removed with a pipet. The oven is then turned off and the sample is allowed to slowly cool to room temperature, e.g. 25° C. The volume at room temperature (V 25 ) is measured for comparison with the volume at 230° C. (V 230 ). The ratio of ##EQU1## represents a fractional change in volume hereinafter referred to as the "fractional volume contraction" or "V"; 100V is the percentage of change in volume and is hereinafter referred to as the "% volume contraction".
In the preferred embodiments of this invention, the capsule wall-forming material is a blend of crystalline olefinic polymer; an amorphous, thermoplastic organic resin; and a wax. If X represents the weight fraction of polyolefin, Y represents the weight fraction of amorphous resin, and Z represents the weight fraction of wax; and V x represents the fractional volume contraction (defined previously) of polyolefin, V y represents the fractional volume contraction of amorphous resin, and V z represents the fractional volume contraction of the wax, the expression ##EQU2## will be greater than one when at least some wax is included in the composition, as is preferred. The expression, of course, approaches 1.0 as the wax concentration approaches zero. Zero wax concentrations result in very low mercury porosimeter readings at the low end of measurable pore size, particularly for the walls of perfect capsules. Grosser pores are sometimes evident in these wax-free capsule walls, but this is a much less preferred type of pore structure. (The solute diffusion rate can be conveniently measured by placing a given weight of capsules in a container with a given volume of water and monitoring the increasing concentration or weight gain of solute in the water, as will be described in detail subsequently.
It will be apparent that the above-noted expression compares the contraction of the total system to the contraction of the polyolefin/amorphous portion of the system. For convenience, this mathematical expression will be hereinafter referred to as the volume contraction ratio, or "VCR". Although capsules with a measureable release rate can be obtained when the "VCR" is 1.0 (see Examples I - III, set forth subsequently), significant improvements in reproducibility and controllability of the capsule wall porosity and solute release rate are obtained when the VCR is greater than 1, preferably greater than 1.2. Apparently, a slight microporosity-creating phase separation effect can occur even when there is only one crystalline and one amorphous phase in the wall-forming system. However, at least three phases provide additional, readily controllable microporosity-creating effects. Crystal structure studies indicate that as the three-component melt cools from the temperature of capsule manufacture, the major (preferably continuous) polyolefin/amorphous resin phase comes out of solution last, leaving dispersed zones of a crystalline or semi-crystalline wax. Further loss of heat from the capsule wall or shell causes the polyolefin/amorphous portion and the wax portion to continue to contract. The aforementioned volume contraction ratio being greater than 1, microscopic (probably including some sub-microscopic) flaws, cracks, pores, channels, or the like are created in the capsule wall with no significant detrimental side effects, e.g. no noticeable increase in weak, imperfect, excessively frangible, or leaky capsules. At least some of the microscopic cracks, pores, etc. will completely traverse the capsule wall, either by a straight forward passage or a torturous route, and capsules with microporous walls are obtained. The existence of microporosity is confirmed by porosimeter studies, using an Aminco-Winslow mercury porosimeter, Model S-7107 or S-7108.
The presence of solute in the capsule walls can be demonstrated by analysis, using a scanning electron microscope having an x-ray detecting feature. One set of analyzed capsules originally contained an aqueous copper sulfate fill solution (25% by weight cupric sulfate-pentahydrate) and were used in a solute release rate test (3 days of leaching into water). The capsules were dried and cut in half. Copper was analyzed for, and detected at, four points in the capsule wall cross-section, ranging from the interior of the wall to its exterior, indicating an actual pass-through of cupric ion from the interior of the capsule toward the exterior.
Based on all the available evidence, one can envision a phase comprising amorphous resin molecules intimately associated with large polyolefin crystals, this polyolefin/amorphous resin phase surrounding a paraffin wax crystal. As the two crystal-containing phases contract, a shearing action takes place between the two crystal types. When the second crystalline phase (i.e. the wax) is omitted, differential rates of contraction are still possible, but the aforementioned shearing action will probably be lost. Crystalline materials such as polyolefin exhibit a greater percent volume contraction than the amorphous materials. In the context of this invention, the percent volume contraction of the polyolefin wil ordinarily be at least 1.2 times greater, and preferably about 2 to 3 times greater than the amorphous resin contraction.
Thus, the capsule membrane (wall or shell) material of this invention, which provides the controlled release feature, is a multi-component blend, preferably a blend of resins and wax. The resin/wax mixture can be prepared so as to tailor the release rate of the encapsulated active ingredient to its desired application. A wide variety of adjustments in the release rate can be made by varying the composition of the capsule walls, both as to the physical properties of the selected ingredient and its weight fraction in the shell-forming melt. Since primarily physical rather than chemical phenomena are involved in the practice of this invention (in fact, chemical interaction between components is not preferred), capsule release rates can be controlled or adjusted by reference to easily calculated or observed criteria. Among these criteria are the volume contraction ratio (VCR, described previously) and the individual fractional volume contractions (V x , etc.), the degree of compatibility of the various wall-forming components at various temperatures, the melting points (or melting ranges) of the individual capsule wall-forming components, eutectic points and liquid-solid curves or tie-lines for component mixtures, the phase relationships (continuous, discontinuous, homogeneous, etc.) as between any plurality of components, and the like. Some of the phase relationships and the like are best determined empirically as well as by reference to known compatibility data, melting points, etc. In many instances, these properties can be determined without first making capsules. Needless to say, however, it is also useful to determine various gross properties of the capsules themselves, including their release rates, crush strength, membrane (i.e. wall or shell) porosity, size, etc. Materials used in this invention for the formation of capsule walls are preferably selected with a view toward providing durable crush-resistant, non-tacky capsules. Microscopic observation techniques have been devised for determining when a capsule bursts or leaks due to compressive forces. For example, two 25 × 75 mm microscope slides with capsules sandwiched between them can be carefully pressed together with the aid of suitable electric motor and clutch arrangement. This crush testing configuration can be calibrated to determine the pounds per square inch (psi) or kilograms per square centimeter force on capsules viewed through the microscope slides. Using this technique, capsule crush strengths in psi ranging from about 5 to about 20 psi have been observed.
As pointed out previously, the volume contraction ratio (VCR) for capsule wall-forming systems of this invention is preferably greater than 1.0, more preferbly greater than 1.2. The VCR cannot be indefinitely increased, however. Excellent porosity of capsule walls has been obtained in practice with a VCR greater than 2.0, but the weight fraction of wax (Z) approaches a very high level as the VCR approaches 3.0. Generally speaking, between 2.0 and 3.0, the amount of wax must be increased to the point where the phase relationship can become inverted, and the wax can become the continuous phase upon cooling. In a typical polyethylene/amorphous hydrocarbon resin/wax blend, this inversion point can be reached at VCR values as low as 2.2. At these high VCR or high wax content levels, the wax becomes the continuous phase and the polyolefin/amorphous resin becomes the discontinuous phase upon cooling of the capsule walls. Relatively low porosity in the capsule walls appears to be a consequence of this phase inversion.
Once the various physical factors (compatibility, melting points, phase relationships, etc.) are properly specified, VCR values for a given range of systems can be made to correlate fairly well with porosity values and/or solute release rates. Anomalous results are likely to be observed, of course, when the capsule wall-forming system is: at a eutectic point, so rich in wax as to produce the wax phase inversion described previously, capable of forming a plurality of dispersed phases, or incapable of forming a continuous matrix for a dispersed phase. These anomalous results may entail a decrease in capsule wall microporosity or some other poorly correlated or undesirable effect, but not necessarily a loss of the solute release feature of this invention.
The preferred components of the multi-component composition used to form the capsule walls of this invention will now be described.
Crystalline Olefinic Polymers
The crystalline polyolefins found useful in the capsule shells of this invention are those which have a specific gravity of about 0.90 to about 0.98, preferably about 0.91 to about 0.95, as determined by the density gradient technique (ASTM Test D 1505-63E). These polyolefins have been found to have molecular weights of about 1,000 to about 4,000, preferably about 1,500 to about 3,500, and exhibit an average viscosity of less than 500 cps at 140° C. (Brookfield viscometer, Model LVT). Polyolefins of higher specific gravity do not appear to be capable of producing as high a porosity in the capsule wall, while polyolefins of lower specific gravity are not sufficiently self-supporting to provide strong capsules. The preferred polyolefins are highly crystalline. The term "crystalline", as used herein, characterizes those olefin polymers which have a definite visible crystal structure as observed through a petrographic microscope. This crystallinity is at least partly responsible for the high fractional volume contraction (V x ) of these polymers, e.g. about 0.15 to about 0.25.
The term "polyolefin" or "olefin polymer" is intended to include homopolymers and those copolymers (including terpolymers, etc.) which have polyolefin character, particularly those which have some crystallinity. Generally speaking, copolymerization interferes with crystal structure; however, if at least about 50 weight percent of the polymer comprises repeating alkylene units (e.g., units derived from ethylene, propylene, 1-butene, or the like) where the polymer consists of at least 75 mole percent of such repeating alkylene units, some crystallinity will be retained, permitting the use of up to 25 mole percent of comonomers such as vinyl acetate, acrylic acid, acrylate ester, vinyl chloride, etc. Higher mole percentages of the monomers vinyl fluoride, vinyl alcohol, and carbon monoxide, are permissible in polyethylene copolymers.
The following is a list of typical commercially available ethylene polymers useful in the invention and their fractional volume contractions (V x ). All of these polymers are manufactured by Allied Chemical Plastics Division and have "AC" commercial grade numbers. Polymer grades AC 617, AC 7, and AC 8 are non-emulsifiable polyethylenes. Grades AC 656, AC 629, and AC 655 are emulsifiable polyethylenes. Grades AC 400, AC 401, and AC 405 are ethylene-vinyl acetate copolymers.
______________________________________ Melt. pt. DensityGrade (° C.) (g/cc) V.sub.x______________________________________AC 617 102 0.91 0.180AC 7 107 0.92 0.227AC 8 116 0.93 0.223AC 656 96 0.92 0.193AC 629 101 0.93 0.180AC 655 104 0.93 0.197AC 400 95 0.92 0.165AC 401 -- -- 0.183AC 405 -- -- 0.180______________________________________
Amorphous Thermoplastic Resins
The amorphous organic resins utilized in the capsule shells of this invention can be one or more of a broad group of materials which are compatible at elevated temperatures at the desired ratio with the polyolefin. By "elevated temperatures" is meant the temperature of capsule manufacture which normally is at least above the melting point of the highest-melting component of the capsule wall-forming composition, preferably at least 100° C. above this highest melting point. The melting points or melting ranges of the preferred amorphous thermoplastic resins are normally in the range of about 50° to about 150° C., preferably between about 85° to about 115° C. It is preferred that the amorphous resins be selected to have a melting point or melting range near the melting point of the polyolefin. The preferred resins belong to a class of materials referred to in industry by the term "hydrocarbon resins". "Hydrocarbon resins" are defined by the Kirk-Othmer Encyclopedia of Chemical Technology, Second Edition, Volume 11, John Wiley & Sons, New York, New York, 1966, page 242 et seq., as the readily thermoplastic polymers of low molecular weight derived from coal-tar fractions, from deeply cracked petroleum distillates, and from turpentine. These "hydrocarbon resins" (which are not hydrocarbon in the strictest sense of the term, since they may contain minor amounts of oxygen or other elements occurring in these natural materials) generally have a molecular weight of about 800 to about 4,000, preferably about 1,000 to about 2,000. Typical "hydrocarbon resins" (as defined by Kirk-Othmer) useful in the practice of this invention include coumarone-indene resins, indene resins, natural and synthetic terpene-based resins, alkyl-aromatic thermoplastic hydrocarbon resins, vinyl arene resins (based on polymers and copolymers of vinyl toluene, styrene, vinyl naphthalene, etc.), wood rosins, asphaltic resins, and other resins described by Kirk-Othmer. Natural and synthetic polyterpene is particularly useful and is commercially available as "Wing-Tack 95" (Goodyear Tire and Rubber Co.), and the various "Piccolyte" resins available from Pennsylvania Industrial Chemical Corporation. From the standpoint of obtaining high compatibility with polyolefins and high porosity in capsule walls, the "Piccopale" resins (Pennsylvania Industrial Chemical Corporation) have been found to be particularly suitable. The "Piccopale" resins are produced by high temperature cracking of petroleum, which produces a mixture of monomers averaging about 90 in molecular weight, including dienes and reactive olefins. Polymerization of this olefinic material produces resins with substantially straight-chain hydrocarbon backbones and some cyclic content, but little or no aromatic content.
The amount of "hydrocarbon resin" and crystalline polyolefins in the capsule wall-forming material are variable but to some extent interrelated. To avoid an excessive contraction rate in the polyolefin/amorphous resin phase, the polyolefin content should not exceed about 95% by weight of the capsule shell or wall composition. The amount of "hydrocarbon resin" is preferably at least about 5% by weight of the total composition for the same reason. It is permissible to lower the polyolefin content to about 15 to 20% by weight, provided that the previously described phase relationships can be properly maintained. These phase relations are most easily obtained when the ratio of polyolefin to amorphous resin is at least 1:1. The amount of wax which can be added is somewhat limited, as will be explained subsequently. It is therefore generally true that drastically decreasing the polyolefin content may require increasing the hydrocarbon resin content and losing some of the diversity in crystal structure between at least two predominantly crystalline phases.
These "hydrocarbon resins" used in this invention exhibit a fractional volume contraction (V y ) which is less than the V x and is preferably in the 0.10 - 0.15 range.
The preferred amount of amorphous "hydrocarbon resin" ranges from about 5 to about 45% by weight of the total capsule wall-forming composition.
Other commercially available amorphous thermoplastic "hydrocarbon resins" include the following materials available from Pennsylvania Industrial Chemical Corporation: "Piccoumaron" resins (polyindine type), "Piccovar" resins (alkyl-aromatic type), "Piccotex" resins (vinyl toluene copolymers), and "Piccolastic" resins (low molecular weight polystyrene type). The fractional volume contraction (V y ) of the aforementioned "Wing-Tack 95" is 0.102.
The fractional volume contractions (V y ) of the aforementioned Piccopale and Piccolyte resins vary slightly depending on the melting points or ranges of the resins. The density of all the common available grades (Piccopales 70 SF, 85 SF, and 100 SF melting at about 70°, 85°, and 100° C., respectively, and Piccolytes S-40, S-85, S-100, and S-135, melting at about 40°, 85°, 100°, and 135° C., respectively) is in the range of 0.96 - 0.98 gram per cubic cm (g/cc) and the V y values are as follows:
______________________________________"Piccopale" "Piccolyte" V.sub.y______________________________________70 SF -- 0.113385 SF -- 0.1200100 SF -- 0.1333-- S-40 about 0.13-- S-85 0.120-- S-100 0.1333-- S-135 about 0.12______________________________________
The Wax Component
The third component of the preferred composition comprises a wax or mixture of waxes, including the natural and/or petroleum and/or synthetic waxes. Again, the wax should be compatible with the other two components at the capsule manufacturing temperature, which temperature will normally be higher than the melting point of the highest-melting component of the mixture used to form the capsule wall. Crystalline paraffinic or other highly crystalline waxes are preferred, the microcrystalline petroleum waxes, the animal and vegetable waxes, the synthetic ester or amide-type waxes, etc. being less preferred. The weight fraction of wax in the capsule wall-forming composition preferably ranges from about 2 to about 25 weight percent. Generally speaking, increasing amounts of wax produce increasing porosity, up to the phase inversion condition described previously. Accordingly, the upper limit of wax concentration is not numerically fixed, but may vary to some degree with the system selected. Stated another way, the quantity of wax should be selected such that the volume contraction ratio (VCR) is at least about 1.2, but preferably not significantly greater than about 2.5. Capsule wall porosities (determined by mercury porisimetry) of at least 3% can be obtained when the wax content is at least 10% by weight.
Typical preferred waxes have a density ranging from about 0.9 to about 1.05, melting points ranging from about 50° to about 90° C., molecular weights ranging from about 300 to about 1500, preferably about 400 to about 800, and fractional volume contractions (V z ) of at least about 20%. The wax component thus has a rate or extent of contraction slightly greater than the preferred polyolefins, and considerably greater than the amorphous thermoplastic resins; hence the wax contraction can be significantly greater than the contraction. of a polyolefin/amorphous resin phase.
Data on suitable commercial paraffin grade waxes ("Shellwax" 100, 200, 300, and 700, available from Shell Chemical Company) are set forth below:
______________________________________Grade Melting Pt.("Shellwax") (° C.) Density V.sub.z______________________________________100 51.4 0.91 0.260200 60.8 0.92 0.257300 70.6 0.93 0.250700 83.9 0.94 0.242Wax Grade MixturesWt % 100 / Wt % 700 V.sub.z10/90 0.23720/80 0.24050/50 0.24380/20 0.250______________________________________
Among the suitable microcrystalline grades are Shellmax 400 (m.p. 80.6° C., density 0.94 g/cc, V z : 0.223) and 500 (m.p. 60.6° C., density 0.93 g/cc, V z : 0.200).
Other suitable wax grades are:
______________________________________Grade m.p. (° C.) Density (g/cc) V.sub.z______________________________________Carnauba 82.5 - 86.1 0.996 - 0.998 0.228Ouricury 82.5 - 84.4 0.97 - 1.050 0.2133Montan 83.0 - 89.0 1.020 - 1.030 0.200______________________________________
Other Additives
It is within the scope of this invention to add high boiling solvents and/or plasticizers to the capsule wall-forming composition. The plasticizer or flexibilizer materials lower the melt viscosity of a capsule wall-forming composition and increase capsule flexibility, thus resistance to breakage. Among the suitable plasticizers are: mineral oil, soya oil, peanut oil, and safflower oil. Anti-oxidants include octadecyl 3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate and other compounds containing sterically hindered phenolic hydroxyls.
Typical water-soluble liquid agricultural chemicals which may be encapsulated for release of the active ingredient are aqueous solutions of urea: ammonium phosphates, sulfates, or nitrates; salts of 2-4, dichlorophenoxy acetic acid, trichloroacetic acid, trichlorobenzoic acid, or dichloropropionic acid; copper salts; potassium salts; salts of 3,6-endoexohexahydrophthalate, disodium and potassium salts being especially preferred; and salts of 1:1' - ethylene 2:2 dipyridylium, the dibromide being especially preferred. Suitable emulsifiable chemicals include the organo-phosphorous compounds disclosed in U.S. Pat. Nos. 3,317,636 and 2,578,652. Solutes or emulsoids which have the ability to chemically or physically attack the capsule walls should be avoided. But virtually any solute, emulsoid or dispersoid which does not have this undesirable property can be used in solution or emulsion form as a fill material for capsules of this invention.
In general, the capsules are formed and filled by forcing a jet of fill liquid through a body of molten capsule shell material, the jet being directed to follow a desired trajectory which causes a concentric shell to form around the liquid fill material. Cooling the molten capsule shell causes it to solidify and form capsules containing liquid fill solution, the capsules being non-tacky and dry on their exterior. See U.S. Pat. No. 3,423,489 (Arens et al), issued Jan. 21, 1969. Other suitable methods of capsule formation are described in the Arens et al. patent and in U.S. Pat. Nos. 2,799,897, 2,911,672, and 3,015,128.
The ability of the capsules to release the contained solute over a period of time is readily demonstrated by extraction techniques. Twenty grams of filled capsules are placed in a sealed bottle together with 100 ml of distilled water and allowed to stand for 24 hours at 25° C. A 10 ml aliquot is thereafter withdrawn, evaporated to dryness, the amount of solid residue determined, and the percent of active ingredient released during the 24 hour period calculated. The remaining solution is decanted and 100 ml of fresh distilled water added, the bottle resealed and allowed to stand for a second 24 hour interval, another aliquot removed, and the percent of active ingredient released is calculated. The procedure is then repeated at various intervals.
The following non-limiting Examples, in which all parts are by weight unless otherwise indicated, illustrate preparation of the capsules of this invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
EXAMPLE I
An apparatus as illustrated in FIG. 1 of U.S. Pat. No. 3,423,489 was used to form capsules filled with an aqueous fertilizer solution. The apparatus contained a submerged, generally upwardly pointed nozzle for discharging fill liquid to be encapsulated. The nozzle was supplied by a conduit means provided with a needle valve to control the flow, and was immersed beneath the surface of a bath of hardenable liquid encapsulating material. The level of the liquid encapsulating material was maintained at an even distance above the nozzle orifice by means of a constant level overflow reservoir provided with a recirculating pump. Air pressure was applied to the reservoir of fill liquid and the nozzle was provided with tip windings of an electrical resistor to minimize congealing of encapsulating material around the nozzle.
The capsule shell comprised 85 parts polyolefin and 15 parts compatible hydrocarbon resin. The nozzle was inclined at an angle of 30° from the vertical, was provided with an orifice of 0.74 mm in diameter, and was immersed in the bath to a depth of 2 mm. The fill liquid had the following composition:
______________________________________ PartsWater 34.0Urea 27.611-37-0 analysis fertilizer (TVA liquidbase solution) 12.010% solution of an interpolymer of methyl vinylether and maleic anhydride ("Gantrez" AN-169,General Aniline and Film Corporation) 25.325% solution of the sodium salt of alkyl arylpolyether sulfonate ("Triton" X-200, Rohm and -Haas Company) 1.1 The shell composition was as follows:Polyolefin, 1,500 molecular weight, 102°C. softening 85.0 point, 0.91 specific gravity, 145 cps viscosity at 140°C. (Polyethylene AC617A,Allied Chemical Co.)Hydrocarbon resin, 95°C. softening point, 0.93 15.0 specific gravity ("Wing-Tack" 95, Goodyear Tire and Rubber Company).______________________________________
Four liters of filtered fill solution were placed in the reservoir to which 0.34 atmospheres gauge pressure was applied. The temperature of the fill liquid was 22° C. The shell composition temperature was 250° C., and the tip winding was heated to about 700° C. The needle valve was opened and the fill solution was discharged at a rate of 133 cm per minute. The polyolefin-hydrocarbon shell composition solidified at a distance approximately 100 cm from the orifice, this time being sufficient to permit the biliquid column to form a string of capsules and then to separate into individual discrete capsules. Capsules were produced at the rate of about 40,000 per minute. The total trajectory length was about 10 feet after which the capsules were allowed to fall into a water filled collecting trough. The capsules collected were 2125 microns in average diameter and had a shell wall thickness of about 120 microns. The fill liquid comprised about 79% of the total capsule weight and the shell material about 21%. The release properties of these capsules were demonstrated by extraction as previously described, the results being shown in TABLE I.
EXAMPLE II
This Example illustrates encapsulation of liquid fertilizer solution in a capsule shell comprising 70 parts of the polyolefin used in Example I and 30 parts of the hydrocarbon resin of Example I. The temperature of the fill solution was 20° C., and the shell composition temperature was 230° C. The fill solution and capsule mixture were discharged at a rate of 149.5 cc/min. Capsules were produced at the rate of about 40,000 per minute. The capsules collected were 2360 microns in average diameter and had a shell wall thickness of about 140 microns. The fill liquid comprised about 75% of the total capsule weight and the shell material about 25%. These capsules were extracted as previously described, the results being shown in TABLE I.
EXAMPLE III
This Example illustrates encapsulation of liquid fertilizer solution in a capsule shell comprising 60 parts of the polyolefin used in Example I and 40 parts of the hydrocarbon resin of Example I. The nozzle angle and trajectory length were substantially the same as utilized in Example I. The temperature of the fill liquid was 22° C. and the temperature of the shell composition was 240° C. Capsules were produced at the rate of about 40,000 per minute. The capsules collected were 2360 microns in average diameter and had a shell wall thickness of about 140 microns. The fill liquid comprised about 75.6% of the total capsule weight and the shell material about 24.4%. These capsules were extracted to demonstrate fertilizer release, the results being shown in TABLE I.
EXAMPLE IV
This Example illustrates the encapsulation of liquid fertilizer in a capsule shell comprising 60 parts of the polyolefin of Example I, 37.5 parts of the hydrocarbon resin of Example I, and 2.5 parts of hydrocarbon wax having a melting point of 84° C., and a specific gravity of 0.94 at 15° C. (Shellwax 700, Shell Chemical Company).
Four liters of filtered fill solution were placed in the reservoir to which 0.34 atmospheres gauge pressure was applied. The temperature of the fill liquid was 20° C. The temperature of the shell composition was 241° C. and the temperature of the tip winding was about 700° C. The needle valve was opened and the fill solution was discharged at a rate of 149.5 cm/min. Capsules were produced at the rate of about 40,000 per minute. The capsules collected were about 2360 microns in average diameter and had a shell thickness of about 140 microns. The fill liquid comprised about 75.6% of the total capsule weight and the shell material about 24.4%. These capsules were extracted as previously described, the results being shown in TABLE I.
EXAMPLE V
This Example illustrates encapsulation of liquid fertilizer in a shell comprising the components used in Example IV, except that the ratio was 60 parts polyolefin, 35 parts hydrocarbon resin, and 5 parts wax. The machine operating conditions were the same as those used in Example IV. The capsules collected were 2360 microns in average diameter and had a shell thickness of about 140 microns. The fill liquid comprised about 75.6% of the total capsule weight and the shell material about 24.4%. These capsules were extracted as previously described, the results being illustrated in TABLE I.
EXAMPLE VI
This Example illustrates encapsulation of liquid fertilizer in a shell comprising the components used in Example IV, the ratio of components being 60 parts polyolefin, 30 parts hydrocarbon resin, and 10 parts wax. Machine operating conditions were the same as those utilized in Example IV. Capsules were produced at the rate of about 40,000 per minute. The capsules collected were 2360 microns in average diameter and had a shell thickness of about 140 microns. The fill liquid comprised about 75.6% of the total capsule weight and the shell material about 24.4%. These capsules were extracted as previously described, the results being shown in TABLE I.
EXAMPLE VII
This Example illustrates encapsulation of a liquid herbicide in a capsule of the invention and illustrates incorporation of a mineral oil plasticizer in the capsule shell. The nozzle was inclined at an angle of about 30° from the vertical, was provided with an orifice 0.74 mm in diameter, and was immersed in the bath to a depth of about 2 mm. The fill liquid was 61.5 parts of a 65% aqueous solution of 1:1' - ethylene 2:2 dipyridylium dibromide ("Diquat", Chevron Chemical Company), 20.6 parts water, and 25.3 parts of a 10% aqueous solution of an interpolymer of methyl vinyl ether and maleic anhydride ("Gantrez" AN-169, General Aniline and Film Corporation).
The shell composition was 59.8 parts of the polyolefin used in Example IV, 21.4 parts of the hydrocarbon resin used in Example IV, 14.5 parts of the hydrocarbon wax used in Example IV, and 4.3 parts mineral oil ("Nujol" liquid petrolatum).
Four liters of filtered fill solution were placed in the reservoir to which 0.27 atmospheres gauge pressure was applied. The temperature of the fill liquid was 22° C. The shell composition temperature was 284° C., and the temperature of the tip winding was about 700° C. The needle valve was opened and the fill solution was discharged at a rate of 106 cc/min. The capsule solidified at a distance of approximately 120 cm from the orifice which was one second travel time of the capsule in the trajectory path. This time was sufficient to permit the biliquid column to first form a string of capsules and then to separate into individual discrete capsules. Capsules were produced at the rate of about 35,000 per minute. The total trajectory length was about 8 feet after which the capsules were allowed to fall into a water filled collecting trough. The capsules collected were 2360 microns in average diameter and had a shell thickness of about 82 microns. The fill liquid comprised about 81.3% of the total capsule weight and the shell material about 18.7%.
The results indicated in TABLE I show that the capsules of this example released less than 5% of their contents during the first 24 hours and released less than 10% of the contents in 5 days. This was considered to be a release rate sufficient to provide an adequate initial dosage of herbicide to the plants and also allow steady release of more herbicide for a definite period of time.
EXAMPLE VIII
This Example illustrates the practical utility of these capsules for use with live tomato plants. An 18-4-4 fertilizer comprising 40.5 parts urea, 5.95 parts NH 4 H 2 PO 4 , 5.8 parts KCl, 47.25 parts water, and 0.5 part surfactant ("Pluronic" L-64) was encapsulated and applied to plants. This fertilizer was encapsulated in the manner utilized in Example I, the capsule shell composition being 59.8 parts of the polyethylene used in Example I, 21.4 parts of the hydrocarbon resin used in Example I, 14.5 parts of the hydrocarbon wax used in Example I, and 4.3 parts non-hydrogenated peanut oil. The shell material comprised 35% of the total weight of the capsule and the fill solution was correspondingly 65%.
Six 6-inch flower pots were filled with vermiculite, another six 6-inch flower pots filled with a low nutrient content soil, and a healthy started tomato plant transferred to each pot. The above fertilizer filled capsules were uniformly incorporated in two pots of vermiculite and in two pots of soil at the rate 11/2 tablespoons per pot (i.e., about 2 lbs. of nitrogen per cubic yard of planting media). One and one-half tablespoons of capsules was also added by top dressing to each of two other pots of vermiculite and to two pots of soil. Two pots of vermiculite and two pots of soil were left as controls without any fertilizer. The plants were all watered with 1/2 to 1 liter of water per day, the progress of plant growth being noted at two week intervals.
Those tomato plants having fertilizer-filled capsules either incorporated in the pot contents or top dressed thereon showed normal growth, bore fruit, and showed no nutrient deficiencies until after 31/2 months. Those plants in pots not containing any encapsulated fertilizer showed nutrient deficiencies after 4 weeks and did not bear fruit.
TABLE I__________________________________________________________________________Cumulative Total Percent of Fill Solution Extracted at Various IntervalsExample1 Day 2 Days 3 Days 4 Days 5 Days 6 Days 7 Days 8 Days 9 Days 10 Days__________________________________________________________________________1 9.36 11.74 12.36 13.08 -- -- 14.53 15.01 15.53 15.902 3.76 5.51 5.73 6.09 -- -- 7.42 7.87 8.40 0.843 5.13 5.5 5.81 5.96 -- -- -- -- -- --4 1.37 1.68 1.79 1.90 -- -- -- -- -- --5 7.76 9.30 10.07 10.61 -- -- -- -- -- --6 9.81 11.51 12.35 12.86 -- -- -- -- -- --7 1.69 2.75 4.04 -- -- 10.27 13.79 17.73 21.78 26.188 7.95 11.05 12.92 14.24 -- -- 16.61 17.49 18.24 --__________________________________________________________________________
EXAMPLES IX - XX
The method of manufacture of these capsules was substantially as in Example I. All capsules had a polyolefin component (polyethylene "AC 617"), a hydrocarbon resin component (Wing Tack 95, described in Example I), and a wax component (Shellwax 700, described in Example IV). Two parts mineral oil were added in Examples XI and XV. The compositions, mercury porosimeter determinations, and the calculated volume contraction ratio (VCR) values of Examples IX - XX are set forth below in TABLE II. The fractional contraction values for the individual components have been given previously. The average daily percent of solute extracted by the standardized water leach test described previously stabilized after the first three days of leaching and was found to be substantially constant for all these Examples, indicating a uniform shell wall porosity as opposed to random gross flows in capsule walls. Further evidence of capsule wall integrity was provided by crush strength data (which also is maximized by the regularity of the capsule shape and the physical strength of the capsule walls). In the crush strength test described in the body of this specification, capsule failure was considered to occur when the tested capsule was observed to leak fluid or burst. The crush strength measurements in all of these Examples were in the range of 11 - 18 psi. A stain test (described subsequently) indicated that the capsules of Examples IX - XX contained no gross flaws. In the leach test column of Table II, a "low" rate indicates less than 1.0 wt. % of active ingredient per day; "moderate" indicates less than 2.0%/day, and "high" indicates greater than 2.0%/day. The active ingredient was copper (II) sulfate pentahydrate, the composition of the fill being:
25.6% cupric sulfate-pentahydrate
72.43% water
1.97% thickener and surfactant
Table II______________________________________(Examples 9-20)Composition* (parts by wt.) Porosity LeachEx. X Y Z MO (Vol. %) VCR Rate______________________________________ 9 45 45 10 0 3.67 1.186 low10 45 40 15 0 10.96 1.264 low11 45 40 15 2 11.87 1.26 low12 45 30 20 0 12.07 1.404 high13 40 35 25 0 9.71 1.548 high14 40 35 25 0 23.11 1.548 high15 40 35 25 2 17.83 1.54 high16 50 15 35 0 24.03 1.781 high17 20 40 40 0 5.23 2.233 **18 44 40 16 0 14.40 1.315 moderate19 43 40 17 0 19.13 1.339 moderate20 42 40 18 0 15.44 1.365 moderate______________________________________ *X is the polyolefin; Y is the hydrocarbon resin; Z is the paraffin wax; MO is mineral oil. **High release rate due to capsule shell wall failure in water. Wax forme continuous phase.
The aforementioned stain test procedure is described below:
A. A small sized strainer was filled with capsules to a depth of 1/4 inch.
B. The strainer was submerged in a reservoir filled with ink (stamp pad ink - solution type, not pigmented type).
C. The capsules were allowed to remain in submerged for 1 minute.
D. The strainer was removed from the ink reservoir and allowed to drain.
E. The capsules were then rinsed with tap water so as to remove all surface ink.
F. The thus rinsed capsules were placed on paper and allowed to dry.
G. Stained flaws or darkened capsules were noted.
No darkened capsules (indicating gross flaws) were noted in any of the preceding Examples. The only stains noted were pinholes, indicating large pores, in the walls of the capsules of Examples XII, XVII, XIX, and XX.
EXAMPLES XXI - XXV
The manufacture of these capsules was as in Examples IX - XX. All capsules had a polyethylene AC 617 (X) component, a hydrocarbon resin (Y) component, and a wax (Z) component. The amounts used in each of these Examples were as follows:
______________________________________ Parts by WeightX: Polyethylene 45Y: Hydrocarbon resin 40Z: Wax 15______________________________________
The data for Examples XXI - XXV are given in Table III.
TABLE III______________________________________(Examples XXI - XXV)Hydrocarbon Porosity LeachEX. Resin Wax (vol. %) VCR Rate______________________________________21 S-100.sup.1 SW700.sup.4 12.14 1.269 low22 100SF.sup.2 SW700.sup.4 11.57 1.269 moderate23 S-85.sup.1 SW700.sup.4 36.98 1.279 low24 WT-95.sup.3 SM500.sup.5 20.71 1.243 low25 85SF.sup.2 SW700.sup.4 16.59 1.279 high______________________________________ Notes .sup.1 "Piccolytes": polyterpenes described previously .sup.2 "Piccopales": synthetic polymerized petroleum hydrocarbons, described previously .sup.3 "Wing-Tack 95": described previously .sup.4 "Shellwax" 700: described peviously .sup.5 "Shellmax" 500: described previously
Examples 21, 23, and 24 showed no staining whatever in the stain test. The other Examples exhibited tiny pinholes. The capsule walls in Examples 23 and 24 appeared to form three incompatible or distinct solid phases upon cooling. The mercury porosimeter values for these two Examples probably indicate high surface roughness, hence, the low leach rates, which otherwise correlate well with the VCR values. Examples 22 and 25 indicate the high pore-forming ability of the Piccopale - containing systems. Crush strength was good for Examples 21 and 22, lower (8.5 - 11 psi) for Examples 23 - 25.
Example XXVI
Capsules were made according to Example X, except that the fill material was the following oil-in-water type emulsion:
______________________________________ Parts by Wt."Abate 4E"(Cyanamid, mosquito larvicide ofU.S. Patent 3,317,636) 3.34Water 58.13Sucrose 28.4320,000 MW polyethylene glycol 9.16Emulsifiers 0.93______________________________________
In actual field trials on field areas of at least 0.1 acre, the capsules were found to provide controlled release of the active larvicide, prolonging the usefulness of the active chemical at least by a factor of 8.
As the preceding Examples indicate, the capsules of this invention provide controlled release of a variety of dissolved or suspended substances. The solvent or other encapsulated liquid can also be controllably released by a transport and evaporation mechanism if the liquid is volatile at the temperature of use. For example, encapsulated water can be used to provide a high humidity environment. Reverse passthrough of solutes or the like is also possible, permitting water-filled capsules to be used to stabilize the concentration of a solute in a given system.
As shown by the aforementioned Arens et al. U.S. Pat. No. 3,423,489, both polar and non-polar, relatively high surface tension liquids, which boil at temperatures above 60° C., e.g. imidazole, alkylene glycols, carboxylic acids, higher alkanes, etc. can be encapsulated in molten organic materials by the biliquid column technique, and hence can be used as fill materials in this invention.
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Microporosity is introduced into a membrane capable of retaining a liquid by (a) forming a single homogeneous liquid phase comprising a first material and a second material, at a temperature above the melting points of said materials, said first material being incompatible with said second material when said liquid phase is cooled to room temperature, the volume contraction ratio being at least about 1.2, and (b) permitting the liquid phase to cool to room temperature, whereby said first material separates out as a dispersed solid phase and creates micropores which extend completely through said membrane. The basic method is used to make capsules by (1) forming the above-mentioned single homogeneous liquid phase into an encapsulating cylindrical stream of liquid concentrically enclosing a core stream of liquid fill material at a temperature below the melting points of the above-mentioned first and second materials, (2) permitting heat exchange to occur, thereby causing said first material to separate out from said homogeneous liquid phase as a multiplicity of microscopic particles dispersed throughout said homogeneous liquid phase, (3) further causing said homogeneous liquid phase to solidify and provide a solid continuous matrix for said particles, while causing said cylindrical stream to constrict and form substantially spherical walls enclosing discrete amounts of said liquid fill material, and (4) hardening said spherical walls into solid microporous capsule walls.
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[0001] This application is a utility application which claims the benefit of priority of U.S. Provisional Patent Application No. 60/295,519, filed on Jun. 4, 2001, entitled “Helmet Sunblocker”.
BACKGROUND OF THE INVENTION
[0002] I. Field of the Invention
[0003] The present invention relates generally to the field of protective helmets and more particularly to a sun and ultraviolet ray visor for protective helmets.
[0004] II. Description of the Related Art
[0005] Motorcyclists are often faced with direct sunlight when operating their motorcycle. The motorcyclist can block the sun by holding his hand between his eyes and the sun. However, by removing either hand from the handlebars causes unsafe driving conditions because both hands are needed to safely operate the motorcycle, right for the front brakes and left for the throttle/clutch, and both hands for control and steering.
[0006] Face mask visors are often used to provide shade for the entire face mask. However, these visors can be undesirable because they sometimes cause too much shading during the day and restrict the motorcyclists vision at night. Similarly, riders also use sunglasses underneath the helmets that can interfere with the use and comfort of the helmet.
[0007] Furthermore, it is known that prolonged exposure to ultraviolet light from the sun can cause damage to the eye.
[0008] Similar problems exist for snowmobilers and other persons who require protective helmets.
SUMMARY OF THE INVENTION
[0009] In general, the invention features a protective helmet visor apparatus and method.
[0010] In general, in one aspect, the invention features a visor apparatus, including an elongated translucent planar strip having a first surface and a second surface, wherein the strip has substantially smooth edges.
[0011] In one implementation, the strip is a material adapted to cling to a surface of a translucent protective face mask.
[0012] In another implementation, the material has static electrical properties that make the material adapted to cling to the surface of the mask.
[0013] In another implementation, the material is poly vinyl.
[0014] In another implementation, the smooth edges are adapted to withstand a force applied substantially parallel to the face mask, and thereby remaining clung to the face mask.
[0015] In another implementation, the force is wind shear.
[0016] In still another implementation, the strip allows transmission of visible wavelengths at a reduced intensity.
[0017] In yet another implementation, the strip prevents transmission of ultraviolet wavelengths.
[0018] In another implementation, the strip is adapted to affix to the inner surface of a motorcycle face mask.
[0019] In another implementation, one edge of the strip includes flaps that are adapted to accommodate motorcycle helmet brow vents, thereby providing sunlight protection throughout the entire upper portion of the helmet.
[0020] In another implementation, wherein the flaps fit in between and around the brow vents.
[0021] In another implementation, wherein the strip further comprises rounded corners.
[0022] In another implementation, the strip is adapted to be cut into various shapes.
[0023] In another implementation, the strip is soft and bendable.
[0024] In another implementation, the strip is optionally polarized.
[0025] In another implementation, the strip further comprises a green tint.
[0026] In another aspect, the invention features a method of providing a visor to a protective helmet face mask, including providing an elongated translucent planar strip having a first surface and a second surface, wherein the strip has substantially smooth edges, mixing soap and water to obtain a soapy mixture, applying a thin layer of the soapy mixture to a location on a surface of the face mask, applying the elongated planar strip to the location on the face mask containing the soapy mixture and smoothing out any air bubbles located between the surface and the strip.
[0027] In one implementation, the planar strip further comprises a series of flaps.
[0028] In another implementation, the method further includes fitting the flaps between and around brow vents on the helmet.
[0029] In another aspect, the invention features a protective helmet visor system, including a protective helmet having a face mask an elongated translucent planar strip attached to a surface of the face mask, the strip having a first surface and a second surface, wherein the strip has substantially smooth edges and rounded corners, and wherein the strip allows transmission of visible light and prevents transmission of ultraviolet light.
[0030] One advantage of the invention is that it protects the rider from ultraviolet wavelengths and attenuates other wavelengths.
[0031] Another advantage is that the invention provides sun protection during the day and does not impede night vision.
[0032] Another advantage is that invention removes the need for additional sun protection such as tinted face masks and sunglasses.
[0033] Another advantage is that the invention allows the rider to use both hands for operation of the vehicle.
[0034] Other objects, advantages and capabilities of the invention will become apparent from the following description taken in conjunction with the accompanying drawings showing the preferred embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] [0035]FIG. 1 illustrates a motorcycle helmet having an embodiment of a visor apparatus;
[0036] [0036]FIG. 2 illustrates a front view of an embodiment of a helmet visor apparatus;
[0037] [0037]FIG. 3 illustrates a top view of an embodiment of a helmet visor apparatus;
[0038] [0038]FIG. 4 illustrates a motorcycle helmet having an alternate embodiment of a visor apparatus;
[0039] [0039]FIG. 5 illustrates a front view of an alternate embodiment of a visor apparatus; and
[0040] [0040]FIG. 6 illustrates a top view of an alternate view of a visor apparatus.
DETAILED DESCRIPTION OF THE INVENTION
[0041] Referring to the drawings wherein like reference numerals designate corresponding parts throughout the several figures, reference is made first to FIG. 1 that illustrates a motorcycle helmet 105 having an embodiment of a visor apparatus 100 . The helmet 105 includes, among other things, a translucent face mask 110 . Many helmets such as helmet 105 include brow vents 115 in the upper portion of the face mask. The brow vents 115 can be adjusted by the wearer of the helmet in order to let air into the helmet. As further described below, the visor apparatus can be affixed to the upper portion of the face mask 110 and adjusted around the brow vents 115 to provide full coverage of sun protection.
[0042] [0042]FIG. 2 illustrates a front view of an embodiment of a helmet visor apparatus 100 . The visor apparatus is typically an elongated flaccid, flexible, soft and bendable strip 100 a . The strip 100 a typically includes properties that allow it to adhere and affix to the face mask of a protective helmet (see FIG. 1 above). In general, the properties that allow this affixation are static electrical properties. In one embodiment, the strip 100 a is comprised of a poly vinyl material. The strip 100 a also includes generally smooth and rounded edges 120 that aid in preventing the strip 105 from being removed from the face mask from forces generally parallel to the strip 100 a such as wind shear.
[0043] The strip 100 a is generally translucent, allowing the transmission of visible wavelengths but includes properties that attenuate various wavelengths of sunlight, thereby reducing the transmitted intensity. In one embodiment, the strip virtually eliminates and prevents the transmission of ultraviolet wavelengths. In general, the strip 100 a can have a variety of tints such as a green tint.
[0044] The visor apparatus 100 generally includes flaps 106 , 107 on one edge of the strip 100 a . The flaps 106 , 107 are adapted to accommodate motorcycle helmet brow vents 115 , thereby providing sunlight protection throughout the entire upper portion of the face mask 110 . The outerflaps 106 provide sunlight protection on the outer edges of the brow vents 115 , and the inner flap 107 provides sunlight protection between the two brow vents 115 . In this way, the rider need not cut or adjust the strip 100 a in order to accommodate the brow vents 115 . The flaps 106 , 107 therefore form recesses 108 into which the brow vents 115 fit. In one implementation, the strip can be further cut to a desired shape.
[0045] The strip 100 a also includes generally rounded corners. The flaps 106 also form two of the corners of the strip 100 a and are shown generally rounded. The two bottom corners 109 are also rounded.
[0046] In another embodiment, the strip 100 a can optionally be polarized or a further polarized strip (not shown) can be added to the strip 100 a in order to filter polarized light and glare such as from a road surface, snow or other reflective surfaces.
[0047] It has generally been determined that the overall length of the strip is about nine inches. To accommodate most brow vents, the length A can be about 2.75 inches and the length B is about 1.625 inches. The length C can be about 3.5 inches. In general, the flap 107 has a height differential with respect to the flaps 106 . The flap 107 is generally higher than flaps 106 . From the lower straight edge, there are generally three heights. The first is the height to the bottom of the recess 108 . The second height is to the top of the flaps 106 . The third height is to the top of the flap 107 . The length of the flap 107 is generally longer than flaps 106 and than the length of the recess 108 . The length recess 108 is generally longer than the length of the flaps 106 . The recess 108 tapers downward to the bottom. The top of the recess 108 is generally longer than the bottom of the recess 108 . In one embodiment, the top of the recess 108 is about 2.375 inches, and the bottom of the recess, B, is about 1.625 inches. These lengths and heights generally accommodate the brow vents.
[0048] [0048]FIG. 3 illustrates a top view of an embodiment of a helmet visor apparatus 100 . This top view shows the flaps 106 , 107 as well as recesses 108 . The edges 120 are generally rounded and smooth as described above with respect to FIG. 2.
[0049] [0049]FIG. 4 illustrates a motorcycle helmet 205 having an alternate embodiment of a visor apparatus 200 . The helmet 205 includes, among other things, a translucent face mask 210 . As further described below, the visor apparatus can be affixed to the upper portion of the face mask 210 or other desired locations of the face mask 210 to provide full protection from sunlight.
[0050] [0050]FIG. 5 illustrates a front view of an alternate embodiment of a visor apparatus 200 . The visor apparatus 200 is typically an elongated flaccid, flexible, soft and bendable strip 200 a . The strip 200 a typically includes properties that allow it to adhere and affix to the face mask of a protective helmet. In general, the properties that allow this affixation are static electrical properties. In one embodiment, the strip 200 a is comprised of a poly vinyl material. The strip 200 a also includes generally smooth and rounded edges 220 that aid in preventing the strip 205 from being removed from the face mask from forces generally parallel to the strip 200 a such as wind shear.
[0051] The strip 200 a is generally translucent, allowing the transmission of visible wavelengths but includes properties that attenuate various wavelengths of sunlight, thereby reducing the transmitted intensity. In one embodiment, the strip virtually eliminates and prevents the transmission of ultraviolet wavelengths. In general, the strip 200 a can have a variety of tints such as a green tint. The strip 200 a can generally be formed and cut into desired shapes. The strip 200 a also includes generally rounded corners 209 .
[0052] In another embodiment, the strip 200 a can optionally be polarized or a further polarized strip (not shown) can be added to the strip 200 a in order to filter polarized light and glare such as from a road surface, snow or other reflective surfaces.
[0053] [0053]FIG. 6 illustrates a top view of an alternate view of a visor apparatus 200 . The edges 120 are generally rounded and smooth as described above with respect to FIG. 2.
[0054] The visor apparatus 200 is generally adapted to affix to the upper portion of the face mask to provide sunlight from generally above and ahead of the rider. However, the visor apparatus 200 can easily be affixed to the bottom portion of a face mask to attenuate reflections from the road surface and other surfaces. The visor apparatus 200 can also be affixed to any desired location on the face mask.
[0055] Generally, the visor apparatuses 100 , 200 is best affixed on the inner surface of the face mask away from external forces such as wind shear. It is understood that the visor apparatuses 100 , 200 can be affixed to the outer surface of the face mask and is adapted to withstand the external forces. The rounded edges 120 , 220 as well as the rounded corners 106 , 109 , 209 are adapted to better withstand the external forces.
[0056] In addition to the adaptations to avoid the apparatus' removal from the face mask, as described above, the rider can also provide further adherence between the face mask and the apparatuses. The rider can mix soap and water to obtain a soapy mixture and apply a thin layer of the soapy mixture to a location on a surface of the face mask as well as to a surface of the apparatus 100 , 200 that is to be affixed to the face mask. The rider can then apply the apparatus 100 , 200 to the desired location on the face mask containing the soapy mixture. Generally, air bubbles may be formed between the apparatus 100 , 200 and the face mask. The rider can simply smooth away the bubbles. The soapy mixture allows the apparatus to be manipulated on the face mask and to easily smooth out the bubbles. It has been determined that the soapy mixture enhances the static electrical forces as well as other surface forces that act in between the apparatus 100 , 200 and the surface of the face mask.
[0057] In other embodiments, the strip 100 a , 200 a has additional features such as a light absorption rate of about 78%. The strip is also about 0.008 inches thick. The strip 100 a , 200 a is static.
[0058] A motorcycle helmet has been used to describe the embodiments. However, it is understood that the embodiments described above can be used with other protective helmets such as but not limited snow mobile helmets, car helmets, riot helmets, hockey helmets, football helmets and other helmets having protective face masks.
[0059] Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, various modifications may be made of the invention without departing from the scope thereof and it is desired, therefore, that only such limitations shall be placed thereon as are imposed by the prior art and which are set forth in the appended claims.
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A protective helmet face mask visor apparatus, method and system is disclosed. The apparatus is adapted to affix to the face mask of a protective helmet at a location where it is desired to impede the transmission of light. The apparatus includes an elongated strip of material that is adapted to transmit visible light and prevent transmission of ultraviolet light.
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority to U.S. Provisional Patent Application No. 61/735,102 and The Netherlands Patent Application No. 2009949, both filed Dec. 10, 2012, the disclosures of which are hereby incorporated by reference in their entirety
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a lifting column for lifting a load, such as a vehicle. Such lifting columns are in particular used for lifting motor vehicles including buses and trucks and may relate to lifting columns of the two-post lift type with pivoting support arms, the four-post lift type with runways, the mobile type etc.
2. Description of Related Art
A lifting column known from practice comprises a frame with a carrier that is connected to a drive for moving the carrier upwards and downwards. In the ascent mode hydraulic oil is pumped to a cylinder for lifting the carrier, and thereby the vehicle. In the descent mode the carrier with the vehicle is lowered and hydraulic oil returns to the reservoir. Lifting columns are designed for a maximum load. Lifting a load with a weight above this maximum leads to unsafe operation of the lifting columns possibly causing accidents with the risk of operators getting injured and vehicles and equipment getting damaged.
The present invention has for its object to provide a lifting column obviating or at least reducing the aforementioned problems.
SUMMARY OF THE INVENTION
This objective is achieved with a lifting column for lifting a load, such as a vehicle, according to the present invention, the lifting column comprising:
a frame with a movable carrier and a drive which acts on the carrier; control means for control of the drive; a carrying part attached to the carrier for carrying the load; weight measuring means attached to the carrying part for measuring the weight of the load; and communication means for communicating a measurement signal of the weight measuring means indicative of the weight of the load to the control means.
By providing the carrying part of the lifting column with weight measuring means, the weight of a load can be measured. More specifically, the weight of a vehicle that is lifted by the lifting column is measured. The communication means communicate a measurement signal that is determined by the weight measurement means and is indicative for the weight of the load that is lifted to the control means. Preferably, the central controller is part of these control means.
The lifting column according to the invention may relate to lifting columns of the two-post lift type with pivoting support arms, the four-post lift type with runways, the mobile type etc.
By providing the controller with weight information of the load the (central) controller knows that a vehicle is present on the carrying part of the carrier. For example, in case of a mobile lifting column the controller may prevent moving the lifting column and/or selecting the lifting column for another group. Furthermore, the controller may perform a check to see whether the weight of the vehicle is below the allowed maximum weight for the specific lifting column, thereby preventing an overload situation. In addition, this check may establish a safety check whether the vehicle is placed correctly relative to the lifting column.
In a presently preferred embodiment the control means that are configured for control of the drive directly or indirectly receive information from the weight measuring means, such as a load sensor. This information is indicative for an authorization to proceed with the lifting operation and/or a command to abort the lifting operation, for example due to a detection of an overload or misalignment of the vehicle on the lifting column. The information from the weight measuring means is preferably received and treated by a central controller. The central controller provides an individual lifting column of a set of lifting columns with the relevant commands, for example for the drive thereof, optionally through the use of an individual controller of a lifting column.
Weight measuring means convert a force caused by the weight of the vehicle that is lifted into an electrical signal. A possible embodiment of the weight measuring means comprises a so-called Wheatstone bridge configuration. For heavier loads an embodiment using a cylinder may be used. Such embodiment enables measuring the deformation as the effective electrical resistance is changed due to the load. Alternative embodiments include the use of piezo-electric load cells and capacitive load cells using a change of the capacitance of the capacitor as indication of the weight of the load. In a presently preferred embodiment the weight measuring means comprise a rubber pad filled with a fluid or gel. The pressure inside the pad is measured with a pressure sensor and represents a measure for the weight. This embodiment can be applied to a lifting column of the two-post lift type. In an alternative embodiment that can be applied to a lifting column of the four-post lift type the pad is positioned under the runways, preferably at or close to one of both outer ends thereof.
The communication means may involve the use of cables connecting the lifting column to a central controller enabling exchange of data representing the measurement signal of the weight measuring means and/or operating instructions, for example.
Preferably, the communication means comprise a transmitter and receiver for wireless communication between the weight measuring means and the control means. The use of wireless communication means may involve the use of Bluetooth, Wi-Fi and/or Ultra Wide Band, for example. Wireless communication prevents the use of cables across the workshop. This improves safety and flexibility for the users of the system. In case the lifting column is a mobile lifting column a battery can be provided to improve the flexibility of the overall lifting system even further. This is especially beneficial for the two-post lifting system with moveable arms.
In a presently preferred embodiment according to the present invention the weight measuring means comprise an energy supply.
By providing an energy supply the weight measuring means can collect measurement data and transfer the measurement signal to the (central) controller without requiring a separate energy supply. The use of a specific energy supply for the measurement means enables performing the measurement and communicating the data autonomously. By providing the energy supply together with the measuring means to the carrier, and more specifically to the carrying part thereof, energy supply cables can be omitted from the lifting system.
Preferably, the energy for the weight measuring means is provided by the vehicle to be lifted. More specifically, the energy is delivered by gravity when lifting the vehicle. This prevents any requirements for external equipment to provide energy.
In a presently preferred embodiment according to the present invention the weight measuring means comprise a piezo-element for generating energy for the energy supply. When a vehicle is positioned on the carrying part, the piezo-element generates a small amount of energy that can be used for the energy supply to the weight measuring means for performing a measurement and communicating a measurement signal to the controller via the communication means. Energy is provided by the vehicle to be lifted, more specifically by gravity when lifting the vehicle. Therefore, no cables and/or external energy sources are required.
In a presently preferred embodiment the energy supply comprises an energy collector for storing the generated energy. This enables storage of energy to be used at the appropriate moment, for example to transfer data via the communication means to the control means. In a presently preferred embodiment the energy collector comprises a capacitor to (temporarily) store energy for use by the weight measuring means and/or the communication means associated therewith.
In a further preferred embodiment according to the present invention the energy supply comprises electromagnetic means for wireless transfer of energy to the weight measuring means.
By providing electromagnetic means an electromagnetic field can be achieved. Preferably, the field is operated by the (central) controller. This enables providing the weight measuring means with energy for performing the weight measurement including transferring data with the communication means to the control means. This enables a standalone weight measurement that in a presently preferred embodiment is integrated in the central controller.
Preferably, the control means comprise operating means for controlling the electromagnetic means. This enables the control means to activate the measurement when required, for example when starting a lifting movement. This results in an energy efficient system.
Preferably, the control means are configured for control of a lifting column or components thereof. In a presently preferred embodiment the control means involve a controller of a first lifting columns acting as master or central controller, and controllers of further lifting columns belonging to the same set of lifting columns acting as slave or local controllers. It will be understood that other configurations of the control means according to the invention are possible. The control means are preferably configure to activate the measurement, receive and treat the measurement data, and send commands to the lifting column(s) and/or components thereof. Next to sending commands and controlling the lifting operation the control means may provide an indication of the load or weight that is measured to the user, operator, driver, or other person. This indication may involve a visual indication that is provided on a display, such as a touch screen, of the control means. Other indication including sound signal may also be applied, for example when an overload is detected.
The invention further relates to a lifting system comprising one or more lifting columns as described above.
Such a lifting system provides the same effects and advantages as those stated with reference to the lifting column. The lifting system preferably uses two, four, six, or even more lifting columns, operating in pairs. Preferably, the control means comprise safety means that are activated when the measurement signal indicates an overweight. This provides additional safety to the lifting system.
The invention furthermore relates to a load sensor for measuring a load on a lifting column and/or lifting system.
Such load sensor provides the same effects and advantages as those stated with reference to the lifting column and/or lifting system. Preferably, the sensor can be used in a lifting system and/or lifting column described above. In a preferred embodiment the load sensor according to the invention comprises an energy generator and/or an energy collector to provide a stand-alone sensor. Preferably the sensor shares its findings with a controller or control system to provide additional safety checks, for example checking an overload.
The invention furthermore also relates to a method for measuring a load on a lifting column, the method comprising: providing a lifting system with a number of lifting columns as described above; and measuring the load.
Such method provides the same effects and advantages as those stated with reference to the lifting column and/or lifting system. Preferably, the method uses the load sensor according to the invention as described earlier. Preferably, the measurement data is provided to the control means, such as the central controller, for example. This enables checking the position of a vehicle relative to a lifting column preventing damage to the columns by an overload and/or providing additional safety to a lifting operation.
BRIEF DESCRIPTION OF THE DRAWINGS
Further advantages, features and details of the invention are elucidated on the basis of preferred embodiments thereof, wherein reference is made to the accompanying drawings, in which:
FIG. 1 shows a schematic overview of a vehicle lifted by lifting columns according to the invention;
FIG. 2 shows a lifting column according to the invention;
FIG. 3 shows an alternative embodiment of a lifting column according to the invention;
FIG. 4 A-B shows a load sensor according to the invention; and
FIGS. 5-7 show alternative embodiments of lifting columns according to the invention.
DESCRIPTION OF THE INVENTION
A system 2 for efficient lifting and lowering a load ( FIG. 1 ) comprises four mobile lifting columns 4 in the illustrated embodiment. Lifting columns 4 lift a passenger car 6 from the ground 8 . Lifting columns 4 are connected to each other and/or a control system by wireless communication means or alternatively by cables. Lifting columns 4 comprise a foot 10 which can travel on running wheels 12 over ground surface 8 of for instance a floor of a garage or workshop. In the forks of foot 10 is provided an additional running wheel (not shown). Lifting column 4 furthermore comprises a mast 14 . A carrier 16 is moveable upward and downward along mast 14 . Carrier 16 is driven by a motor 18 that is provided in a housing of lifting column 4 . Motor 18 is supplied with power from the electrical grid or by a battery that is provided on lifting column 4 in the same housing as motor 18 , or alternatively on foot 10 (not shown). Control panel 20 is provided to allow the user of system 2 to control the system, for example by setting the speed for the carrier 16 .
A column 22 ( FIG. 2 ) of a lifting system 24 is a mobile lifting column that communicates by transmitter-receiver 26 to a transmitter-receiver 28 of a central controller 30 . A connection 32 to the electrical grid is provided on a side wall 33 in the neighbourhood of controller 30 . Sensor 34 is capable of measuring a load of vehicle 6 carried by carrying part 36 . The resulting measurement signal is communicated via transmitter 38 to transmitter-receiver 28 of controller 30 directly or indirectly through transmitter-receiver 26 . Controller 30 may send data to lifting column 22 such as an activation signal for sensor 34 using transmitter-receiver 28 and receiver 40 . It will be understood that transmitters and/or receivers 26 , 38 , 40 can be combined or separated. In the illustrated embodiments sensor 34 is a piezo-electric sensor.
In an alternative embodiment a lifting column 42 of lifting system 44 ( FIG. 3 ) comprises load sensor 46 . Energy supply system 48 comprises a piezo-element 50 that generates energy when a load is positioned over carrying part 36 . The energy is stored in capacitor 52 that is used to transmit data to controller 30 .
A sensor 54 ( FIG. 4 A-B) comprises pressure plate 56 . Below plate 56 an illustrated gel-pad 58 is provided that rests on a stationary plate 60 . In the illustrated embodiment plate 60 is connected by weld 62 to housing 64 . Channel 66 brings the gel of pad 58 into contact with pressure sensor 68 . Processing module 70 determines the measurement signal 72 . Transmitter 74 sends signal 76 representing the load acting on sensor 54 . In the illustrated embodiment channel 78 brings gel of pad 58 into contact with power generator 80 . The generated energy can be stored in power buffer 82 and used by transmitter 76 .
In a presently preferred embodiment pressure sensor 68 comprises a thin film and/or semiconductor, power generator 80 comprises a piezo-element, and buffer 82 comprises a capacitor and/or a rechargeable battery.
When measuring a load of vehicle 6 , carrying part 36 that is lifted by carrier 16 of lifting columns 4 , 22 , 42 receives an activation signal from controller 30 using transmitter/receivers 26 , 28 , 38 , 40 for activating sensor 34 , 46 . Sensor 34 , 46 performs the measurement and transfers the measurement data to controller 30 using the same or similar transmitter/receivers. The energy required for sensor 46 is in one of the illustrated embodiments of lifting column 42 provided by piezo-element 50 and capacitor 52 . This obviates the need to provide additional cables for the measuring system. In another embodiment the energy required for sensor 46 is provided by electromagnetic means 54 that are preferably activated by controller 30 .
In addition, controller 30 may perform additional tasks using the measurement signal including a check to prevent overweight. In case an overweight is established, controller 30 may prevent operation and more specific load lifting by lifting column 4 , 22 , 42 . For example, when lowering a vehicle a load sensor may detect a small overload of column 4 , 22 , 42 such that controller 30 may stop the operation. Furthermore, controller 30 may check the correct positioning of vehicle 6 over a pair of lifting columns 4 , 22 , 42 of lifting system 24 , 44 . Also, controller 30 may provide an operator with a clearance signal if necessary and/or a warning signal in case of a problem.
The present invention can be applied to the (wireless) lifting columns illustrated in FIGS. 1-3 . Alternatively the invention can also be applied to other types of lifting columns and lifting systems.
For example, a four-post lifting system 102 ( FIG. 5 ) comprises four columns 106 carrying runways 106 . Columns 104 comprise a sensor 108 , preferably each column 104 has one sensor 108 . In the illustrated embodiment an indicator 110 with a green light 112 and a red light 114 is provided. Light 110 signals to the driver when vehicle 6 is positioned correctly relative to columns 104 and the vehicle 6 can be lifted. In case each column 104 is provided with sensor 108 the position of vehicle 6 on carriage way/carrier 106 can be checked. In addition, the individual load for a specific lifting column 104 can be checked. This contributes to the overall safety of the lifting operation. Furthermore, by preventing overloads to occur in practice columns 104 can be designed effectively thereby reducing costs.
As a further example, lifting system 202 ( FIG. 6 ) comprises a so-called sky-lift configuration with four posts 204 carrying runways 206 . In the illustrated embodiment a sensor 208 is provided for every post 204 . This enables the check on positioning of vehicle 6 and/or the individual loads acting on a post 204 as described earlier. A light 210 with green 212 and red 214 lights can be provided on wall 216 to indicate to the driver of vehicle 6 that the vehicle is positioned correctly or needs to be repositioned.
As an even further example, lifting system 302 ( FIG. 7 ) comprises a so-called two-post configuration with two posts 304 that are provided with carrier arms 306 . In the illustrated embodiment carrier arms 306 are provided with sensor 308 . This enables the check on positioning of vehicle 6 and/or the individual loads acting on a post 304 as described earlier. A light 310 with green 312 and red 314 lights can be provided to indicate to the driver of vehicle 6 that the vehicle is positioned correctly or needs to be repositioned.
It will be understood that the invention can be applied to a range of lifting systems, including but not limited to four-post and two-post lifting columns, skylift, and mobile columns. Also, it will be understood that additional embodiments of the invention can be envisaged combining and/or switching features from the described and/or illustrated embodiments. For example, instead of light 110 , 210 , or in addition thereto, sound signals, indications on a control system etc. can be applied.
Providing signals, such as warning signals of an overload or misalignment of the vehicle, can be provided in numerous ways. This may involve the use of lights, sounds, visual indications on a display, such as a touch screen, of a lifting column, etc.
The present invention is by no means limited to the above described preferred embodiments. The rights sought are defined by the following claims within the scope of which many modifications can be envisaged. The present invention is described using a lifting column and more specifically a mobile lifting column and/or a lifting column of the two-post and/or four-post lift type. The invention can also be applied to other type of lifting columns such as so-called boom-lifts, scissor-lifts and loading platforms. Such lifting equipment can be provided with the measures illustrated above according to the invention.
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Disclosed is a lifting column for lifting a load, such as a vehicle, which includes a frame with a movable carrier and a drive which acts on the carrier; control means for control of the drive; a carrying part attached to the carrier for carrying the load; weight measuring means attached to the carrying part for measuring the weight of the load; and communication means for communicating a measurement signal of the weight measuring means indicative of the weight of the load to the control means.
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FIELD OF THE INVENTION
This invention relates to portable computers and, more specifically to the capability to relocate and reposition the cursor actuator control on the computer housing for more convenience, efficiency, and comfort. The cursor actuator control actuates a computer operation which then is depicted by the position of a cursor relative to an icon or symbol and displayed on the monitor or computer display.
BACKGROUND OF THE INVENTION
Mouse buttons, the common term for control push-buttons, are used to control a computer through the identification of an icon by the cursor and the operation of the cursor actuator buttons. The control push-buttons are intended to be ergonomically located and typically are positioned either on the top surface or an edge surface of the keyboard section the portable computer. Within the wide audience of users, mouse buttons do not accommodate all people nor are convenient and comfortable for all.
Operating a portable computer with hands in a normal typing position to the keyboard almost inherently places the thumbs over or near the computer mouse buttons and may unintentionally activate one of the mouse buttons, causing the computer to initiate a computer operation that is not intended or desired. An inadvertent actuation of the computer operation may result in as little inconvenience as having to reverse the operation to return to the present task, or as much as a complete loss of all the work performed up to that point on a particular project. To avoid any inadvertent or unintentional occurrences by these computer-housing located mouse buttons, it is desirable to relocate them in a position relative to the keyboard that will prevent such accidental activation.
Laptop computers are becoming the communication device of choice for making presentations, particularly when the presentation is made to an individual. Laptop computers are also used in conjunction with overhead or other types of projectors to provide enlarged projections of graphics to larger groups. The graphic displays to be shown are electronically stored in memory, called up, and displayed in the desired sequence in response to a cursor being positioned over an icon or a command block displayed on the computer display, then the operator depresses a mouse button or cursor actuator control button. With fixed cursor actuator controls on the keyboard section of the computer, a presenter must reach from a side position to a position in front of the individual viewing the presentation in order to activate the cursor actuation control button to progress through the presentation. If making a one-on-one presentation, this presents a significant distraction to the viewer, not only offsetting a portion of the benefit of using the portable computer but also it is awkward and uncomfortable.
Further, to provide one-on-one training on the usage of laptop computers or software loaded thereon, the reach to the cursor actuator control buttons is difficult and awkward for the presenter.
Although most portable computers can accommodate a separate mouse, any extra device creates inconvenience in carrying and storage as well as distractions during setup.
OBJECTS OF THE INVENTION
It is an object of the invention to provide the operator of a portable computer the ability to position cursor actuator controls or mouse buttons in positions to avoid any inadvertent actuation of these controls.
It is another object of the invention to provide in a portable computer the ability to position the cursor actuation controls so that the cursor actuation controls are comfortably operable by a person positioned to one side of the computer.
It is a further object of the invention to provide in a portable computer the ability to position the cursor actuation controls wherein the position of the controls may be optimized for the person who predominately uses the computer while allowing adjustments for other operators.
It is an additional object to provide a cursor actuator control in a portable computer which may be laterally displaced relative to the keyboard section of the computer.
SUMMARY OF THE INVENTION
The cursor actuator control in the form of a pair of push-button controlled switches may be movably positioned within the region between the keyboard of a portable or laptop computer and the operator. The cursor actuator control may be pivotally displaced, slidably displaced, or both; displacement allows an operator to move the cursor actuator control out of a position subject to inadvertent actuation or to a more ergonomic or comfortable position.
The cursor position control itself may take the form of a conventional wobble post in the keyboard or a touch pad positioned within the arcuate path of movement of the cursor actuator control buttons. Both the wobble post and touch pad cursor position controls are conventional and used on various portable or laptop computers. Touch pads, as previously implemented, are fixed in location and/or orientation.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an illustration of a portable computer having a cursor actuator control which is displaceable relative to the keyboard portion of the computer housing.
FIG. 2 is an illustration of the portable computer of FIG. 1 with the cursor actuator control dislocated to the left.
FIG. 3 is an illustration of a portable computer having a cursor actuator control which is translatable laterally across the keyboard portion of the computer housing.
FIG. 4 is an illustration of a segment of the keyboard portion of the portable computer of
FIG. 3 wherein the cursor actuator control unit is both translatable as well as rotatable relative to the keyboard of the computer.
FIG. 5 is an illustration of a portable computer having a cursor actuator control surrounded by a rotatable control ring with a plurality of finger indentations in the control ring to aid in the rotation of the cursor actuator control.
FIG. 6 is an enlarged illustration of the cursor actuator control shown in FIG. 5 .
FIG. 7 is an illustration of a portable computer with a cursor actuator control wherein the control buttons are independently movable to alternate positions.
FIG. 8 is an enlarged illustration of a cursor actuator control of the type shown in FIG. 7 with a touch pad cursor positional control disposed within the arcuate paths through which the cursor actuator controls may be moved.
FIG. 9 is a block diagram illustrating the connections between the cursor positional control, the cursor actuator control, the display, and the computer processor.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
OF THE BEST MODE OF THE INVENTION
AS CONTEMPLATED BY THE INVENTOR
In this detailed description, the term “mouse controls” relates to and is used to identify and describe either a pair of depressible buttons or switches which are the equivalent of the finger controlled push-to-make switches found on a traditional desktop mouse or those depressible buttons and associated switches that perform equivalent functions on the face or edge of a keyboard portion of a portable or laptop computer. These buttons and switches cooperate with the computer and are combined with a computer recognized position by an arrow or other cursor icon on the display of the computer relative to the displayed graphics. The operation of the cursor actuator control or mouse controls create a cursor actuation control command which initiates the operation of the computer to perform the function as represented by the portion of the display graphics over which the cursor is positioned at the time a button is depressed and the corresponding switch is actuated.
Like reference numerals are used in the various figures to designate like elements and may appear in a plurality of the figures without a specific description of the element with regard to each figure. In instances wherein there is no description of an elements in regard to a figure but the element is described with regard to another figure, the description relates to all figures in which the numbered element appears.
Should the mouse buttons or cursor actuator controls 10 be located in a position uncomfortable and/or inconvenient for the operator, mouse buttons 10 may be moved relative to the keyboard section or portion 12 of portable computer 14 as illustrated in the various drawings. This description refers to FIG. 1, initially, which shows a laptop or portable computer 14 with the mouse button 10 displaceable in an arc 16 as indicated here by arrow 16 , disposed intermediate the normal operator position and keyboard 18 itself and positioned within the keyboard portion 12 of computer 14 .
The exterior of the keyboard section 12 of the computer 14 forms a circular guide 15 within which the mouse buttons 10 are movable. The internal mouse control switches (not shown) may be electrically connected by flexible circuit cables or other conductors (not shown).
Cursor actuator control 10 and cursor position control 20 together constitute a “mouse” or mouse control assembly 26 , common usage terms for a device for controlling a cursor position and activating a command indicated graphically by the cursor 22 .
The cursor position control 20 is typically a movable or wobble post or joy stick 20 disposed between individual keys of the keyboard 18 and, in fact, is found in a multitude of laptop computers. Movement by the user's index finger of post 20 is converted to signals which, in turn, control any movement and/or positioning of cursor 22 across the face of the display 24 . The cursor position control 20 operates to generate signals representing direction and velocity to move the cursor 22 about the face of the display 24 of the computer 14 , and ultimately electronically indicating a particular location or symbol on display 24 . The position of cursor 22 , typically an arrow symbol 22 , together with an electrical signal generated by the cursor actuator controls or mouse buttons 10 input a command to the computer 14 as is conventional and well understood by those of skill in the art of computer and mouse design. The combined signals are utilized by the microprocessor to initiate a command for a computer operation if a computer operation is indicated.
The cursor position control 20 and the cursor actuator controls 10 are connected to the computer electronics in the same manner as and function as the prior art counterparts and may be constructed and connected to control the computer 14 by one who is of ordinary skill in the art of computer design.
With hands in normal keyboarding positions, thumbs are thus over the cursor actuator control buttons 10 . This positioning can create problems for those who tend to rest their hands and particularly the heel of their hands on the computer; they may inadvertently actuate a cursor designated command.
Swivelling the entire cursor actuator control assembly 26 to the left, as in FIG. 2, or to the right repositions the cursor actuator control 10 to a more protected position from one where inadvertent actuation is likely. Mouse buttons 10 may be similarly displaced to the right, if desired by the operator.
The position of the cursor actuator control 10 is maintained by a locking device, such as a push-to-release mechanism controlled by release button 28 . The locking device need only be as simple as a friction pad spring-biased against a portion of the cursor actuator control assembly 26 .
As laptop computers have gained in capability and popularity, many are now used for making graphic presentations instead of using graphic charts or a projector and slides of transparencies. In most instances, such as this, the presentation graphics are controlled by the actuation of a cursor actuator control to page through the previously prepared graphics of the presentation. Currently, in order to avoid the problems associated with the position of the cursor actuator control, a conventional mouse must be connected to the portable computer.
With the present cursor actuator control swivelled to one side, the presenter may more easily and comfortably use the cursor actuator controls 1 0 while positioning an observer directly in front of the somewhat narrow viewing field of the screen of display 24 . Liquid crystal displays are the most common type displays 24 used on portable and laptop computers. Thus, the intended viewer must be positioned within the narrow angle of view of the display.
FIGS. 3 and 4 illustrate a computer 14 or a portion of a computer 14 having a cursor actuator control 30 formed in a rotatable unit 30 that is additionally translatable laterally across the keyboard portion 12 of the computer 14 . FIG. 4 illustrates only the movable cursor actuator control unit 30 and its retaining and guiding track 32 . The rotatable control unit 30 is guided and retained by track 32 formed in and by the case of computer 14 .
Rotatable control unit 30 carries the mouse buttons 10 or cursor actuator controls 10 which are electrically connected to the computer processor ( 40 in FIG. 9) in a conventional manner. The electrical connection between the cursor actuator controls 30 may be made of flexible circuit cables and either discrete wires or commutators. Rotatable unit 30 is provided with a depression 34 in the surface which permits insertion of a finger tip to translate or rotate the rotatable unit 30 relative to the computer 14 .
FIGS. 5 and 6 illustrate a control similar to that shown in FIGS. 3 and 4 except that the rotatable unit 30 provides a plurality of finger indentations or depressions 34 and the rotatable unit 30 is a complete ring. capable of full rotation.
FIG. 7 illustrates the mouse control 38 where the cursor actuator control buttons 10 are independently mounted and may be moved in opposite directions either to dispose the buttons 10 out of the way of an user's hands and thumbs or to accommodate the positional desires of the operator. Cursor positional control 20 is similarly disposed in the midst of keyboard 18 .
An alternative to the cursor positional control 20 is a touch pad 50 illustrated in FIG. 8 . The touch pad 50 may be formed in an ellipse, oval, circle or other convenient shape. Touch pad 50 is conventional in construction and is conventionally connected to the computer processor ( 40 in FIG. 9 ). The touch pad 50 may be fixed in a single lateral location or may be translatable on a rotatable member such as illustrated in FIGS. 3 and 4. The touch pad 50 may be rotatable to one side or the other so that the X-Y axis of the touch pad 50 may be oriented as desired by the operator with the same angular relation as the cursor actuator control 30 in FIG. 3; or, if of an elongated shape, touch pad 50 may remain fixed relative to the keyboard portion 12 of computer 14 . Even if touch pad is fixed and remains oriented at an angle to the user, the human brain can compensate and the user still may control the cursor accurately and efficiency.
Refer now to FIG. 9, a portion of the portable computer is illustrated in diagrammatic form. Computer processor 40 connects directly to all the other components illustrated 10 , 20 , 24 . Computer processor 40 provides the signals to display 24 not only to produce and display the material, including icons and control blocks, but also to produce, display, and move a cursor on display 24 .
Control of the cursor (not shown) is provided by the cursor position control 20 and cursor actuator control 10 . The cursor position control 20 generates signals representative of the direction and velocity with which the cursor is to move; and, the cursor actuator control 10 generates signals which command the computer processor 40 to perform an operation, the identification of the operation being the icon or control block displayed on the display 24 and having a cursor symbol positioned thereon.
The software incorporated into the computer processor for accepting the signals from the cursor position control 30 and the cursor actuation control 10 and for initiating the indicated computer function is conventional and well known to those of skill in the art of computer design.
It will be understood by one of skill in the art of computer design that in light of the above detailed description of the invention, translatable and rotatable cursor actuator and/or rotatable touch pad may be implemented such that it is positioned on top of the keyboard portion of the computer or may be incorporated into the keyboard portion, as shown. One of skill in the art will also understand that other changes and variations in the design of the computer may result in minor changes and variations in the cursor actuation control device and its positioning and relationship relative to the computer without removing the modified device from the scope of the attached claims which define the invention.
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Mounting the cursor actuator control or mouse buttons on the keyboard portion of a portable computer in a manner to permit the translation of the cursor actuator control across the keyboard portion of the portable computer, thereby allows the positioning of the cursor actuator control for comfort and convenience of the operator. The ability to relocate the cursor actuator control further allows any operator of the portable computer to minimize inadvertent operation thereof by the accidental and unintentional contact of user's thumb with the cursor actuator controls.
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RELATED APPLICATION
This application is a continuation application of U.S. patent application Ser. No. 09/245,732, filed Feb. 8, 1999, now abandoned, which in turn is a continuation-in-part application of U.S. patent application Ser. No. 09/119,439, filed Jul. 20, 1998, now abandoned, which in turn is a continuation of U.S. patent application Ser. No. 08/788,472, filed Jan. 28, 1997, now U.S. Pat. No. 5,782,794, which issued Jul. 21, 1998.
BACKGROUND OF THE INVENTION
1. Field Of Invention
The present invention is directed to an improved tampon applicator. More particularly, the present invention is directed to a tampon applicator having a plastic-type body or coating that has been treated. Even more particularly, the tampon applicator is either molded of a polymer resin, or coated with a polymer resin, with the outside surface of the applicator then treated with infrared radiation.
Consumers desire tampon applicators that make pledget insertion easier, more convenient and less messy. In particular, for environmental reasons as well as for convenience of disposal, consumers desire applicators, especially tampon applicators, that are both biodegradable and water-soluble. An example of a water-soluble polymer used for making flushable applicators is polyvinyl alcohol (also referred to herein as “PVOH”).
However, PVOH, in particular, is known to become sticky on contact with moist surfaces or under humid conditions. Heat treatment of the PVOH applicator provides crystallization that increases water resistance, but too much heat makes PVOH unacceptably stiff and brittle.
The present invention overcomes the disadvantages described above associated with tampon applicators made from water-soluble polymers in an efficient manner, and provides tampon applicators either made from, or coated with, water-soluble polymers that are able to withstand exposure to moisture, but are not unacceptably stiff. The present invention accomplishes the foregoing by heating only the outside of the applicator with infrared radiation.
U.S. Pat. No. 5,782,794, the grandparent of the present application, discloses a novel set of plasticizers suitable for use with PVOH that, in conjunction, produce a molded product having improved stability, ease of molding, and utility for tampon applicators. The disclosure of U.S. Pat. No. 5,782,794 in its entirety is incorporated herein by reference.
2. Description of the Prior Art
Tampon applicators typically are constructed from two telescoping tubes. One tube, a barrel, encloses the pledget, and the other tube, a plunger, is used to eject the pledget out of the barrel during insertion. Thus, it is essential that the tubes telescope smoothly to facilitate ejection. Any stickiness or other adhesions between the two tubes can result in poor ejection of the pledget, which in turn can make insertion of the pledget difficult, painful, or impossible. One solution to the foregoing problem is to make the diameter of the plunger less than the diameter of the barrel. However, if the plunger is much less in diameter than the barrel to prevent sticking together, the plunger will most likely disassemble from the barrel.
Furthermore, the ability of the barrel to be inserted smoothly, without dragging on the delicate vaginal tissue, is very important not only for users comfort but also for proper insertion of the pledget. Once again, any stickiness or adhesion sites on the outer surface of the barrel will impede proper insertion.
Tampon applicators formed from certain polymer resins, when dry, have glide characteristics similar to traditional plastic tampon applicators. Thus, such polymer resin tampon applicators would be expected to have optimal qualities for insertion, minimal drag on insertion and smooth telescoping of the barrel and plunger. In addition, these polymer resin tampon applicators remain dispersible and biodegradable on disposal in water.
However, the very ability of the polymer resin tampon applicators to disperse in water also creates certain drawbacks. Water-soluble polymer resins, can become sticky on contact with moist surfaces, bodily fluids or under humid conditions. Thus, tampon applicators formed from polymer resins tend to become tacky in the very environment for which it is designed. This in turn makes insertion more difficult, since the outer tube can become gummy or tacky upon insertion. Another potential problem should such a polymer resin applicator be exposed to moisture, is that the barrel and plunger may not telescope properly. The barrel and plunger may even become glued together, requiring a much greater force to eject the tampon pledget from the applicator. Additionally, humidity from the environment can permeate the packaging used to store the polymer resin tampon applicator and, thus, cause the same problems. Humidity may even cause the applicator to stick to the wrapper.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a water dispersible tampon applicator that has been treated with infrared radiation to avoid or minimize adverse moisture effects on the tampon applicator.
It is another object of the present invention to provide a polymer tampon applicator that has been treated with infrared radiation so that the applicator will not become sticky or begin to biodegrade upon initial contact with moist surfaces, bodily fluids or ambient humidity.
It is a further object of the present invention to provide a cardboard tampon applicator that has been coated with a water-soluble resin and then treated with infrared radiation so that the applicator will not become sticky or begin to biodegrade upon initial contact with moist surfaces, bodily fluids or ambient humidity.
It is still a further object of the present invention to provide a polymer tampon applicator that has been treated with infrared radiation so that the outside surface is crystallized to increase water resistance, yet the applicator remains flexible and, thus, usable.
Accordingly, the present invention discloses a tampon applicator having a barrel and a plunger that is telescopically mounted within the barrel. Either or both the barrel or plunger is made of, or coated with, a water dispersible polymer. The barrel or plunger is exposed to or treated with infrared radiation to minimize surface stickiness thereof when exposed to moisture.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a tampon applicator employing a preferred method of the present invention; and
FIG. 2 is a diagram of a preferred method of treating a tampon applicator according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings and, in particular, FIG. 1, there is a tampon applicator generally represented by reference numeral 10 . The applicator 10 has an outer tube or barrel 12 and an inner tube or plunger 14 . The barrel 12 preferably has a curved or petal tipped end 18 , and a plunger insertion end 22 . The barrel 12 preferably has a plurality of fingergrips 16 . The plunger 14 has an insertion end which has an edge 24 . Upon assembly, pledget 20 is located within barrel 12 , and plunger 14 is inserted in end 22 of the barrel. The edge 24 of plunger 14 will act against pledget 20 when the plunger is moved to eject the pledget through and out of end 18 of barrel 12 .
The barrel 12 and plunger 14 can be made of any water dispersible material. Examples of suitable water dispersible polymers are microbial polyesters such as poly(b-hydroxy butyrate)(“PHB”), poly(b-hydroxy butyrate)-co-(b-hydroxy valerate)(“PHBV”), poly(hydroxy acids), aliphatic polyesters, polycaprolactone (“PLC”), starch, cellulose acetate and cellulose diacetate.
Alternatively, either or both the barrel 12 and plunger 14 may be made of other materials, and then coated with a water dispersible polymer. Any of the water dispersible polymers set forth above may be used as the coating for the barrel or plunger.
Although either or both the barrel and plunger may be made of, or coated with, the water dispersible polymer, it is preferable that both the barrel and plunger are either made of, or coated with, the water dispersible polymer.
In one preferred embodiment, barrel 12 and plunger 14 are made of one water-soluble polymer resin. In a second embodiment, the barrel is made of the water-soluble polymer resin, and the plunger is made of another material, such as cardboard.
The tampon applicator assembly includes the barrel 12 and plunger 14 assembled together with the pledget 20 in the barrel. As shown in FIG. 2, the tampon applicator assembly is placed in a rotating carrier 26 . The barrel 12 and plunger 14 are rotated in the rotating carrier 26 while the carrier is subjected to infrared (or “IR”) radiant heater or heaters (hereinafter “IR Source”) 28 . As shown in FIG. 2, the heater 28 is preferably positioned approximately six inches from the carrier 26 . As can be understood, the distance of the IR source 28 from the tampon applicator may be modified. However, as the distance of the IR source from the tampon applicator is modified, the temperature generated by the IR source 28 and the length of time of IR exposure will require adjustment as would be evident to those in the art.
The barrel 12 and plunger 14 are preferably treated with the IR Source 28 positioned about six inches from the carrier 26 for about five to about sixty seconds. The temperature of the IR Source is preferably from about 700° F. to about 2500° F. The effect of the IR treatment is time-temperature dependent. Thus, when the temperature of the IR Source is higher, the length of time required for IR exposure will decrease.
The temperature of the IR source 28 and the time period of IR exposure will be a function of the water-soluble polymer resin used. The polymer resin is heated to a level just below the melting point of the polymer resin. The infrared treatment affects the outer surface of the tampon applicator 10 by inducing high temperature molecular crystallinity along the backbone of the polymer resin. The polymer should not be heated to the melting point since only the cystallization of the outermost layer of the polymer resin is desired. The crystallization results in a more hydrophobic surface thereby providing a less sticky surface. However, since only the outermost layer of the polymer resin is crystallized by exposure to the IR source 28 , the overall flexibility of the tampon applicator is not substantially diminished as seen with prior art methods.
Examples of melting point ranges of several polymers that may be used with the present invention are listed below in Table 1.
TABLE 1
POLYMERS
MELTING POINT ° C.
Polycaprolactone (PCL)
58-60
Poly(b-hydroxy butyrate)
40-180
Poly (b-hydroxy butyrate)-co-(b-Hydroxy
40-180
Valerate) (PHBV)
Aliphatic Polyesters
200
Cellulose Acetate (CA)
240
The examples of melting points set forth in Table 1 is intended only to provide a guideline. The melting point ranges of any specific polymer is available from the manufacturer of that particular polymer.
The most preferred conditions for infrared treatment of tampon applicators made of, or coated with, PVOH are:
Temperature (° F.) of
Time (seconds)
IR Source
Condition A
40
1325
Condition B
20
1750
This infrared treatment does not destroy, deform or degrade the petals of the applicator. Thus, this entire tampon applicator can be treated, whereas other known treatments would affect the petals. In prior treatments, the petals required protection during treatment, i.e. only the applicator body minus the petals could be treated.
U.S. Pat. No. 5,782,794, discussed above, is directed toward the application of the present invention for tampon applicators either made of, or coated with, PVOH. This patent illustrates that tampon applicators treated with infrared treatment demonstrate substantially improved performance in comparison with the conventional, non-IR treated PVOH applicators. A home use test of 100 respondents was performed. Specifically, tampons having (1) PVOH barrels infrared treated as set forth above (with untreated cardboard plungers); and (2) untreated applicators having barrels and plungers of traditional polyethylene were tested.
# Preferring
# Preferring
IR Treated
Untreated
No
Preference
Attribute
PVOH
Polyethylene
Preference
Ratio
Easy to insert
32
29
39
+1.1
Comfortable to
29
25
46
+1.1
Insert
Easy to Eject
32
29
45
+1.1
From Applicator
Easy to Grip
25
22
53
+1.1
Overall Comfort
28
20
52
+1.2
Smoothness of
27
23
35
+1.1
Applicator
The applicator
38
38
24
1.0
A similar study was conducted comparing untreated PVOH applicators to traditional, untreated polyethylene applicators. All applicators were the same in size, shape, dimensions and fingergrips. The results below show that consumers clearly preferred the untreated polyethylene applicators to untreated PVOH applicators.
# Preferring
# Preferring
Untreated
Untreated
No
Preference
Attribute
PVOH
Polyethylene
Preference
Ratio
Easy to insert
13
43
28
−2.1
Comfortable to
14
42
28
−2.0
Insert
Easy to Eject
11
38
35
−1.9
From Applicator
Easy to Grip
20
15
49
+1.1
Overall Comfort
8
22
54
−1.4
Smoothness of
8
43
33
−2.4
Applicator
The applicator
26
40
18
−1.4
In summary, the results of these two tests show consumers clearly prefer the infrared treated PVOH (as compared to untreated polyethylene applicators) over untreated PVOH applicators. When comparing the preference ratios derived from the first experiment with infrared treated PVOH applicators (center column, below) versus untreated PVOH applicators the difference is obvious. This demonstrates the dramatic difference in product acceptability that is conferred by the infrared treatment of the present invention.
Preference Ratio
Preference Ratio
IR Treated PVOH
Untreated PVOH
Comfortable to insert
+1.1
−2.0
Easy to insert
+1.1
−2.1
Easy to eject
+1.1
−1.9
Easy to grip
+1.1
+1.1
Smoothness of applicator
+1.1
−2.4
The applicator
+1.0
−1.4
Overall comfort
+1.2
−1.4
Accordingly, the IR treated PVOH applicator has similar consumer acceptance ratings to the traditional polyethylene applicator, even before taking into account the consumer preference for flushable and biodegradable applicators. This is a substantial improvement over the results for the untreated PVOH applicator. Furthermore, the IR treated PVOH may have scored even better with a treated PVOH plunger instead of the cardboard plunger used in the test.
The consumer testing results set forth above demonstrate that the advantages of treating with infrared heat tampon applicators made from, or coated with, water-soluble polymers. It is believed by the applicants that the present invention is as effective with the polymer resins disclosed herein as has been proven with the consumer test studies conducted with PVOH.
Thus, it will be obvious to one of ordinary skill in the art that the foregoing description and drawings are merely illustrative of certain preferred embodiments of the present invention, and that various obvious modifications can be made to these embodiments in accordance with the spirit and scope of the appended claims.
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A tampon applicator has a barrel and a plunger telescopically mounted within the barrel. In a preferred embodiment, one or both of the barrel and plunger is made of a water dispersible material, and is exposed to a source of infrared radiation to minimize surface stickiness on initial contact with moisture. In an alternative embodiment, the barrel or plunger can be coated with a water dispersible material prior to exposure to infrared radiation.
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FIELD OF THE INVENTION
This invention relates to an automatic tool for assembling electrical terminals.
BACKGROUND OF THE INVENTION
Various types of electric terminals are well known in the art, and many have some type of metal connector which is crimped to the exposed end of a wire. In the most common of these terminals, the metal connector has a piece of insulation wrapped around its end into which the exposed portion of the wire is inserted for crimping. The crimped connection between the wire and the metal for these terminals is not always satisfactory, however, because the crimping tool must squeeze the metal through the surrounding semi-rigid insulation. Further, because the insulation is permanently attached to the connector before crimping, it is difficult to visually determine whether or not the crimp connections are good ones.
In another type of terminal, the metal connector has no insulation, and the crimping tool acts directly on the metal. This results in a better electrical connection between the metal and the wire, and it is a connection which can be visually inspected. After this connection has been made, a hollow box-like insulator is then slipped over the entire metal connector and the crimp connection, thereby providing protection for the entire connector. Despite these advantages, however, the box insulator terminals are hand assembled, and thus they are not widely used because of their cost.
SUMMARY OF THE INVENTION
I have discovered that a tool for assembling electrical terminals with box insulators can be constructed by providing piston means which sequentially and automatically retain wire in place for crimping, crimp the wire to a metal connector positioned in a work station, and slide the box insulator over the connector and the crimped connection, after which the finished terminal is removed and the tool automatically advances another connector and insulator to the work station for assembly.
In the preferred embodiment, the tool is a head attachment for an air-operated press. Once a metal connector and a box insulator are in a work station of the tool, the operator places the wire to be crimped into the connector. A first piston then moves a slide which locks a pair of mechanical jaws around the wire thereby holding it in place. Next the pistons of the press force a pair of crimping tools onto the connector and the wire and crimp them together. A second piston of the tool then moves another slide which pushes a box insulator over the entire metal connector and the crimped connection. Both slides are then retracted by the pistons, which releases the jaws holding the wire and the completed terminal and advances the next insulated box and metal connector into place into the work station to repeat the process.
DESCRIPTION OF THE PREFERRED EMBODIMENT
I turn now to a description of the preferred embodiment, after first describing the drawings.
FIG. 1 is a perspective view of the tool of this invention;
FIG. 2 is a cross-sectional view taken along lines 2--2 of FIG. 3;
FIG. 3 is a cross-sectional view taken along lines 3--3 of FIG. 1;
FIG. 4 is an exploded view of the terminal to be assembled by this invention; and
FIGS. 5 A, B, and C are side views of the sequence of operation of the tool of this invention.
STRUCTURE
Referring to FIG. 1, a tool for assembling an electrical terminal with a box insulator is shown at 10.
The tool 10 basically comprises a tool block 20, a slide housing 74 and first and second pistons, 110 and 112 respectively. The block 20, the slide housing 74 and the pistons 110, 112 are mounted on a T-shaped base plate 14 which is bolted (bolts not shown) to an air-operated press 150 of the type disclosed in my U.S. Pat. No. 4,195,565, incorporated herein by reference. The tool 10, however, may be used with other presses.
The tool block 20 comprises a front cover 22, a pair of mid-sections 24, 26 and a rear plate 28, all bolted together to form a smooth, curved surface 29 having a work station 30 at its apex. The block 20 has a jaw assembly 32, a portion of which protrudes through slot 34 immediately in front of the work station 30. As best shown in FIGS. 2 and 3, the jaw assembly 32 comprises a pair of jaws 36, 38 having a corresponding pair of legs 40, 42, which legs are disposed inside the block 20. The legs 40, 42 are connected by a spring 44 attached to dowels 46, 48 on each leg. The jaws 36, 38 and legs 40, 42 are held together by a pivot pin 50 attached at one end to a slide plate 52. The opposite end of the pin 50 protrudes through a slot 54 in the front cover 22. Slide plate 52 has a roller 56 on its bottom edge, and each leg 40, 42 also has a roller 58, 60 on their ends opposite the jaws 36, 38. As will be explained hereinafter in more detail, the jaw assembly 32 can move up and down, and the legs 40, 42 can separate thereby opening the jaws 36, 38.
The mid sections 24, 26 of the block 20 support a wire anvil 62 and an insulation anvil 64, both immediately in front of the work station 30. The anvils 62, 64 are fixed in place.
As shown in FIG. 3, the rear plate 28 supports a shaft 66 for a sprocket wheel 68. The sprocket wheel 68 is connected to a ratchet and pawl assembly 70, which has roller bearing cam 72 extending downwardly therefrom.
The slide housing 74, which is immediately to the rear of the block 20, has a tape guide 76 with a slot 77. The slot 77 fits over spokes 69 of the sprocket wheel 68. The guide 76 is positioned above and separated from the curved surface 29 of the block 20. As shown in FIG. 3, slide housing 74 also has a top slot 78 and a bottom slot 80. The top slot 78 is positioned immediately to the rear of the work station 30, and it contains a slide assembly 82 having a carrier 84 and a projecting slide 86. The slide 86 has a pointed front face 88. The end of the carrier 84 opposite the slide 86 receives a shaft 90 from the first piston 110, and the slide assembly 82 can reciprocate in the slot 78.
A wire stop 92 is attached to the slide housing 74 above the slide assembly 82. The end of the wire stop 92 opposite the slide housing 74 has a flat face 94, which is normally positioned between the anvils 62, 64 and the work station 30. A spring clip 96 holds the wire stop 92 down.
The bottom slot 80 of the slide housing contains the jaw cam slide 98. One end of the jaw cam slide 98 is attached to a shaft 100 of the second piston 110. As best shown (dotted) in FIG. 1, the opposite end of the jaw cam slide 98 has two tapered side faces 102, 104 and a tapered top side 106. The rollers 58, 60 of the legs of the jaw assembly 32 contact the side faces 102, 104 while the roller 56 of the slide plate 52 contacts the top side 106. The jaw cam slide 98 also has a cam opening 108 into which roller bearing 72 for the ratchet and pawl assembly of the sprocket wheel 68 fits.
The pistons 110, 112 are connected to the air supply for the press 150. The press itself has, as shown in FIG. 1, an elevated tool holder 120 which is supported by rods 122 (only partially shown) each of which has a spring 124 (only a portion of one shown) to provide a return force. The holder 120 supports a wire roll tool 130 and an insulation roll tool 132 which are positioned directly above the anvils 62, 64.
OPERATION
The basic operation of the invention is best explained with reference to FIGS. 4 and 5. As shown in FIG. 4, the terminal to be assembled comprises a metal contact 200, a hollow insulation box 202 and a wire 204. The metal contact 200 has a contact section 206 with curled sides 207, and a rear tail 208. The tail 208, which is in the form of a trough, has a first pair of projections 210 and a second and larger pair of projections 212 at its rear. The contact section 206 is inserted into the hollow insulation box 202 leaving the tail 208 exposed, and the box is mounted with tape (not shown) on a film strip 214 having a series of slots 216.
In operation, the film strip 214 is slipped under the tape guide 76 so that the slots 216 engage the spokes 69 of the sprocket wheel 68. Then sprocket wheel 68 is rotated until the first box 202 with the contact tail 208 exposed is at the work station 30, as shown in FIG. 5A. In this position, the exposed tail 208 of the contact 200 is above the anvils 62, 64. In particular, the first pair of projections 210 are above the wire anvil 62 and the second and large projections 212 are above the insulation anvil 64.
In this position, the face 94 of the wire stop 92 is disposed between the box 202 and the first pair of projections 210. The operator then takes the wire 204 which has a small exposed end 205 and inserts it in the trough-like tail 208 of the contact 200 until the end 205 of the wire 204 hits the wire stop face 94. The wire 204 is then in position for crimping. The second piston 112 is then activated, and it pushes the jaw cam slide 98 forward. The rollers 58, 60 on the legs of the jaw assembly 32 slide along the tapered sides 102, 104 of the front of the jaw cam slide 98, and this opens the legs 40, 42, as shown in FIG. 2. This movement of the slide 98 also causes the jaw assembly slide plate 52 to roll up the tapered top side 106. This forward movement of the jaw cam slide 98 in effect causes the jaw assembly 32 to move upward out of the block 20 while closing the jaws 36, 38 around the wire just behind the tail 208 of the contact 200.
As shown in FIG. 5B, the press 150 then forces the holder 120 downward so that the tools 130, 132 pass over the anvils 62, 64, thereby bending the projections 210, 212 around the exposed wire 205 and the adjacent portion of the insulated wire 204. The holder 120 then retracts.
Finally, the first piston 110 pushes the slide assembly 82 forward. The movement of the slide 86 forces the wire stop 92 up and out of the way, and at the same time pushes the box 202 over the entire contact 200. The face 88 of the slide 86 also cuts away the tape holding the box 202 to the film. The slide is then retracted by piston 110. The terminal is now complete, and the second piston 112 retracts the jaw cam slide 98. The jaws 36, 38 release the wire 204 and the jaw assembly 32 drops back into the housing 20. The retraction of the jaw cam slide 98 also causes the roller bearing cam 72 to rotate in the cam opening 108, and the racket and pawl assembly 70 rotates thereby advancing the sprocket wheel 68 and moving the next unassembled box and contact into the work station.
Other embodiments of the invention will occur to those skilled in the art and are within the scope of the following claims.
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A tool for automatically assembling electrical terminals with a box insulator comprising a piston-activated jaws assembly for securing a wire in place in a work station so that press-driven tools can crimp the wire to a metal connector, after which a piston-activated slide forces an insulated box over the metal connector and its crimped connection thereby completing the assembly.
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FIELD OF THE INVENTION
[0001] This invention relates to the field of polyfluorinated compounds containing an ether linkage within the polyfluorinated chain, and particularly to such fluorophosphates, and to their use as surfactants and additives for coating compositions or as treatment agents to impart various surface properties to substrates.
BACKGROUND OF THE INVENTION
[0002] Polyfluorinated compositions are used in the preparation of a wide variety of surface treatment materials. These polyfluorinated compositions are typically made of perfluorinated carbon chains connected directly or indirectly to nonfluorinated functional groups capable of further reaction such as hydroxyl groups, carboxylic acid groups, halide groups and others. Various compositions made from perfluorinated compounds or polymers are known to be useful as surfactants or treating agents to provide surface effects to substrates. Surface effects include repellency to moisture, soil, and stains, and other effects, which are particularly useful for fibrous substrates and other substrates such as hard surfaces. Many such surfactants and treating agents are fluorinated polymers or copolymers.
[0003] Most commercially available fluorinated polymers useful as treating agents for imparting surface effects to substrates contain predominantly eight or more carbons in the perfluoroalkyl chain to provide the desired properties. Honda et al, in Macromolecules, 2005, 38, 5699-5705 teach that for perfluoroalkyl chains of greater than 8 carbons, orientation of the perfluoroalkyl groups, designated R f groups, is maintained in a parallel configuration while for such chains having less than 6 carbons, reorientation occurs. This reorientation decreases surface properties such as contact angle. Thus polymers containing shorter chain perfluoroalkyls have traditionally not been successful commercially for providing surface properties to treated substrates.
[0004] EP 1 238 004 (Longoria et al.) discloses a mixture of a fluoroalkyl phosphate and a fluoroacrylate polymer for use in providing stain resistance to stone, masonry, and other hard surfaces.
[0005] It is desirable to improve particular surface effects and to increase the fluorine efficiency; i.e., boost the efficiency or performance of treating agents so that lesser amounts of the expensive fluorinated composition are required to achieve the same level of performance, or so that better performance is achieved using the same level of fluorine. It is desirable to reduce the chain length of the perfluoroalkyl groups thereby reducing the amount of fluorine present, while still achieving the same or superior surface effects.
[0006] There is a need for compositions which significantly improve the repellency and stain resistance of fluorinated treating agents for substrates while using lower levels of fluorine. There is also a need for polymer compositions useful as additives in coatings, such as paints, stains, or clear coats, to provide resistance to blocking and enhanced open time extension. The present invention provides such compositions.
SUMMARY OF THE INVENTION
[0007] The present invention comprises a composition comprising one or more compounds of formula (I) or (II):
[0000]
[0000] wherein:
[0008] R f is a linear or branched perfluoroalkyl having one to seven carbon atoms, optionally interrupted by one to three oxygen atoms,
[0009] r and q are each independently an integer of 1 to 3,
[0010] j is 0 or 1, or a mixture thereof,
[0011] x is from about 1 to about 2,
[0012] Z is —O—, —S—, or —NR—,
[0013] R is hydrogen or an alkyl group containing 1 to 4 carbon atoms,
[0014] X is hydrogen or M, and
[0015] M is an ammonium ion, an alkali metal ion, or an alkanolammonium ion.
[0016] The present invention further comprises a method of providing water repellency, oil repellency and stain resistance to a substrate comprising contacting the substrate with the above described formula (I) or (II) or mixtures thereof.
[0017] The present invention further comprises a method of providing oil repellency, resistance to blocking, and open time extension to a substrate having deposited thereon a coating composition comprising addition to the coating composition prior to deposition on the substrate of a composition of the above described formula (I) or (II) or mixtures thereof.
[0018] The present invention further comprises a substrate to which has been applied a composition of the above described formula (I) or (II) or a mixture thereof, or a coating composition containing the above described formula (I) or (II) or a mixture thereof.
DETAILED DESCRIPTION OF THE INVENTION
[0019] Hereinafter trademarks are designated by upper case.
[0020] This invention comprises compositions of formula (I) and (II) as described above containing an ether linkage within the polyfluorinated chain designated R f . The compositions are useful for contributing surface protection properties to paper, tiles, stone and other hard surfaced substrates. The compositions are also useful as surfactants, and as additives to coating compositions to provide surface-modifying properties to substrates coated therewith.
[0021] While, for simplicity, this invention will generally refer to the above compositions as fluoroalkylphosphates, it is to be recognized that one skilled in the art can readily apply this invention to other phosphorus derivatives of the fluoroalcohols and fluorothiols such as the corresponding fluoroalkylphosphites or fluoroalkylphosphinates. The present invention includes such fluoroalkylphosphites and fluoroalkylphosphinates. Similarly, while this invention salts will generally refer to the fluoroalkylphosphate salts as amine salts, it is to be recognized that that one skilled in the art can readily apply this invention to the corresponding ammonium or alkali metal salts, which are included within the invention.
[0022] The present invention comprises a composition comprising compounds of formula (I) or (II) or mixture thereof as described above.
[0023] In the compositions of the present invention R f is preferably a linear perfluoroalkyl group having one to six carbon atoms, more preferably one to four carbon atoms, and more preferably one to three carbon atoms. Preferred are compositions of formula (I) wherein r and q are 1, and X is ammonium.
[0024] The fluoroalcohols used as starting materials to make the compositions of the present invention are available by the following series of reactions:
[0000]
[0025] The starting perfluoroalkyl ether iodides of formula (V) above can be made by the procedure described in U.S. Pat. No. 5,481,028, herein incorporated by reference, in Example 8, which discloses the preparation of compounds of formula (V) from perfluoro-n-propyl vinyl ether.
[0026] In the second reaction above, a perfluoroalkyl ether iodide (V) is reacted with an excess of ethylene at an elevated temperature and pressure. While the addition of ethylene can be carried out thermally, the use of a suitable catalyst is preferred. Preferably the catalyst is a peroxide catalyst such as benzoyl peroxide, isobutyryl peroxide, propionyl peroxide, or acetyl peroxide. More preferably the peroxide catalyst is benzoyl peroxide. The temperature of the reaction is not limited, but a temperature in the range of 110° C. to 130° C. is preferred. The reaction time can vary with the catalyst and reaction conditions, but 24 hours is usually adequate. The product is purified by any means that separates unreacted starting material from the final product, but distillation is preferred. Satisfactory yields up to 80% of theory have been obtained using about 2.7 mols of ethylene per mole of perfluoroalkyl ether iodide, a temperature of 110° C. and autogenous pressure, a reaction time of 24 hours, and purifying the product by distillation.
[0027] The perfluoroalkylether ethylene iodides (VI) are treated with oleum and hydrolyzed to provide the corresponding alcohols (VII) according to procedures disclosed in WO 95/11877 (Elf Atochem S.A.). Alternatively, the perfluoroalkylether ethyl iodides can be treated with N-methyl formamide followed by ethyl alcohol/acid hydrolysis. A temperature of about 130° to 160° C. is preferred. The higher homologs (q=2, 3) of telomer ethylene iodides (VI) are available with excess ethylene at high pressure.
[0028] The telomer ethylene iodides (VI) are treated with a variety of reagents to provide the corresponding thiols according to procedures described in J. Fluorine Chemistry, 104, 2 173-183 (2000). One example is the reaction of the telomer ethylene iodides (VI) with sodium thioacetate, followed by hydrolysis. The telomer ethylene iodide (VI) can also be treated to provide the corresponding thioethanols or thioethylamines by conventional methods.
[0029] Specific fluoroether alcohols useful in forming compounds of the invention include those listed in Table 1A, and specific fluoroether thiols useful in forming compounds of the invention include those in Table 1B. The groups C 3 F 7 , C 4 F 9 , and C 6 F 13 , referred to in the list of specific alcohols and thiols in Tables 1A and 1B, refer to linear perfluoroalkyl groups unless specifically indicated otherwise.
[0000]
TABLE 1A
F 3 COCF 2 CF 2 CH 2 CH 2 OH,
F 3 CO(CF 2 CF 2 ) 2 CH 2 CH 2 OH,
C 2 F 5 OCF 2 CF 2 CH 2 CH 2 OH,
C 2 F 5 O(CF 2 CF 2 ) 2 CH 2 CH 2 OH,
C 3 F 7 OCF 2 CF 2 CH 2 CH 2 OH,
C 3 F 7 O(CF 2 CF 2 ) 2 CH 2 CH 2 OH,
C 4 F 9 OCF 2 CF 2 CH 2 CH 2 OH,
C 4 F 9 O(CF 2 CF 2 ) 2 CH 2 CH 2 OH,
C 6 F 13 OCF 2 CF 2 CH 2 CH 2 OH,
C 6 F 13 O(CF 2 CF 2 ) 2 CH 2 CH 2 OH,
F 3 COCF(CF 3 )CF 2 OCF 2 CF 2 CH 2 CH 2 OH,
F 3 COCF(CF 3 )CF 2 O(CF 2 CF 2 ) 2 CH 2 CH 2 OH,
C 2 F 5 OCF(CF 3 )CF 2 OCF 2 CF 2 CH 2 CH 2 OH,
C 2 F 5 OCF(CF 3 )CF 2 O(CF 2 CF 2 ) 2 CH 2 CH 2 OH,
C 3 F 7 OCF(CF 3 )CF 2 OCF 2 CF 2 CH 2 CH 2 OH,
C 3 F 7 OCF(CF 3 )CF 2 O(CF 2 CF 2 ) 2 CH 2 CH 2 OH,
[0000]
TABLE 1B
F 3 COCF 2 CF 2 CH 2 CH 2 SH,
F 3 CO(CF 2 CF 2 ) 2 CH 2 CH 2 SH,
C 2 F 5 OCF 2 CF 2 CH 2 CH 2 SH,
C 2 F 5 O(CF 2 CF 2 ) 2 CH 2 CH 2 SH,
C 3 F 7 OCF 2 CF 2 CH 2 CH 2 SH,
C 3 F 7 O(CF 2 CF 2 ) 2 CH 2 CH 2 SH,
C 4 F 9 OCF 2 CF 2 CH 2 CH 2 SH,
C 4 F 9 O(CF 2 CF 2 ) 2 CH 2 CH 2 SH,
C 6 F 13 OCF 2 CF 2 CH 2 CH 2 SH,
C 6 F 13 O(CF 2 CF 2 ) 2 CH 2 CH 2 SH,
F 3 COCF(CF 3 )CF 2 OCF 2 CF 2 CH 2 CH 2 SH,
F 3 COCF(CF 3 )CF 2 O(CF 2 CF 2 ) 2 CH 2 CH 2 SH,
C 2 F 5 OCF(CF 3 )CF 2 OCF 2 CF 2 CH 2 CH 2 SH,
C 2 F 5 OCF(CF 3 )CF 2 O(CF 2 CF 2 ) 2 CH 2 CH 2 SH,
C 3 F 7 OCF(CF 3 )CF 2 OCF 2 CF 2 CH 2 CH 2 SH,
C 3 F 7 OCF(CF 3 )CF 2 O(CF 2 CF 2 ) 2 CH 2 CH 2 SH
[0030] The compositions of formula (I) and (II) of the present invention are prepared according to the method described by Longoria et al in U.S. Pat. No. 6,271,289, and Brace and Mackenzie, in U.S. Pat. No. 3,083,224 each herein incorporated by reference. Typically, either phosphorus pentoxide (P 2 O 5 ) or phosphorus oxychloride (POCl 3 ) is reacted with a fluoroalcohol or fluorothiol to give mixtures of the mono- and bis(perfluoroalkyl)phosphoric acids. Neutralization, using common bases such as ammonium, sodium hydroxide, or an amine provides the corresponding phosphates. Reacting an excess of fluoroalcohol or fluorothiol with P 2 O 5 followed by neutralization provides a mixture of mono(perfluoroalkyl)phosphate and bis(perfluoroalkyl)phosphate. Higher ratios of bis(perfluoroalkyl)phosphate to mono(perfluoroalkyl)phosphate are obtained by using the method of Hayashi and Kawakami in U.S. Pat. No. 4,145,382. The phosphite and phosphinate compositions are prepared in the same manner.
[0031] The resulting composition is then diluted with water, mixture of water and solvent, or further dispersed or dissolved in a solvent selected from the groups comprising simple alcohols and ketones that are suitable as the solvent for final application to substrates (hereinafter the “application solvent”). Alternatively, an aqueous dispersion, made by conventional methods with surfactants, is prepared by removing solvents by evaporation and the use of emulsification or homogenization procedures known to those skilled in the art. Such solvent-free emulsions may be preferred to minimize flammability and volatile organic compounds (VOC). The final product for application to a substrate is a dispersion (if water based) or a solution (if solvents other than water are used).
[0032] It will be apparent to one skilled in the art that many changes to any or all of the above procedures can also be used to optimize the reaction conditions for obtaining maximum yield, productivity or product quality.
[0033] The present invention comprises fluorinated aqueous mixtures comprising a mixture of an anionic aqueous fluoroalkyl phosphate (or phosphite or phosphonite) solution neutralized with a base, preferably an amine such as dialkanolamine base. The composition is neutralized to a pH of from about 5 to about 10, preferably from about 6 to about 9, more preferably from about 6 to about 8.
[0034] The various molar ratios of the fluoroalcohol or fluorothiol, acid, and base can be identified by the format (a:1:b): thus the (2:1:1) salt is, for example, the bis(fluoroalkyl) phosphate amine salt, the (1:1:2) salt is, for example, the fluoroalkylethyl phosphate bis(amine salt) and the (1:1:1) salt is, for example, the fluoroalkylethyl phosphate amine salt. Preferably the (2:1:1) salt is the bis(fluoroalkylethyl) phosphate diethanolamine salt, the (1:1:2) salt is the fluoroalkylethyl phosphate bis(diethanolamine salt) and the (1:1:1) salt is the fluoroalkylethyl phosphate diethanolamine salt. The salts of the fluoroalkylphosphates are preferred over the corresponding acids by reason of their increased water solubility.
[0035] The salts of the fluoroalkylphosphates are preferred over the corresponding acids as outlined in U.S. Pat. No. 3,083,224 by reason of their increased water solubility.
[0036] The present invention further comprises a method of providing water repellency, oil repellency, and stain resistance to a substrate comprising contacting the substrate with a composition of formula (I) or (II) as defined above, or a mixture thereof. The composition of the present invention is typically applied by contacting the substrate with the composition by conventional means, including but not limited to, brush, spray, roller, doctor blade, wipe, immersion, dip techniques, foam, liquid injection, casting, and the like. Optionally, more than one application can be used, particularly on porous surfaces.
[0037] When used on stone, tile and other hard surfaces, the compositions of the invention are typically diluted with water to give an application solution having about 0.1 weight % to about 20 weight %, preferably from about 1.0 weight % to about 10 weight %, and most preferably from about 2.0 weight % to about 5.0 weight %, of the composition based on solids. The coverage as applied to a substrate is about 100 g of application solution per sq meter (g/m 2 ) for semi-porous substrates (e.g. limestone) and 200 g/m 2 for porous substrates (e.g. saltillo). Preferably the application results in about 0.1 g/m 2 to about 2.0 g/m 2 of solids being applied to the surface.
[0038] When used as a surface treatment for paper, the compositions of the invention are typically diluted with water to give an application solution having about 0.01 to about 20 weight %, preferably about 0.1 weight % to about 10 weight %, and most preferably about 0.5 weight % to about 5 weight %, of the composition based on solids. The coverage as applied to paper is about 10 g/m 2 to about 200 g/m 2 , and preferably about 10 g/m 2 to about 200 g/m 2 of the application solution. Preferably the application results in about 0.1 g/m 2 to about 5.0 g/m 2 of solids being applied to the paper.
[0039] The compositions of the present invention are also used as an additive during the manufacture of substrates. They are added at any suitable point during manufacture. For example, in the case of paper, they are added to the paper pulp in a size press. The amount added is from about 0.3% to about 0.5% by weight based on dry fluorochemical solids on dry paper fiber.
[0040] The composition of this invention is applied to or contacted with the substrate as such, or in combination with one or more other finishes or surface treating agents. The composition of the present invention optionally further comprises additional components such as treating agents or finishes to achieve additional surface effects, or additives commonly used with such agents or finishes. Such additional components comprise compounds or compositions that provide surface effects such as stain repellency, stain release, soil repellency, soil release, water repellency, oil repellency, odor control, antimicrobial, sun protection, and similar effects. One or more of such treating agents or finishes can be blended with the composition of the present invention and applied to the substrate.
[0041] Other additives commonly used with such treating agents or finishes can also be present such as surfactants, pH adjusters, leveling agent, wetting agents, and other additives known by those skilled in the art. Examples of such finishes or agents include processing aids, foaming agents, lubricants, anti-stains, and the like. The composition is applied at a manufacturing facility, retailer location, or prior to installation and use, or at a consumer location.
[0042] The present invention further comprises a method of providing resistance to blocking, open time extension and oil repellency to a substrate having deposited thereon a coating composition comprising adding to the coating composition prior to deposition on the substrate of a composition comprising one or more compounds of formula (I) or (II) as described above, or a mixture thereof. The compounds are employed as additives to the coating composition, and are added and mixed into the composition. Suitable coating compositions, referred to herein by the term “coating base”, include typical paints, stains, and clear coats, usually a liquid formulation, of an alkyd coating, Type I urethane coating, unsaturated polyester coating, or water-dispersed coating. Such coating compositions are applied to a substrate for the purpose of creating a lasting film on the substrate surface.
[0043] By the term “alkyd coating” as used herein is meant a conventional liquid coating based on alkyd resins, typically a paint, clear coating, or stain. The alkyd resins are complex branched and cross-linked polyesters containing unsaturated aliphatic acid residues. Conventional alkyd coatings utilize, as the binder or film-forming component, a curing or drying alkyd resin. Alkyd resin coatings contain unsaturated aliphatic acid residues derived from drying oils. These resins spontaneously polymerize in the presence of oxygen or air to yield a solid protective film. The polymerization is termed “drying” or “curing” and occurs as a result of autoxidation of the unsaturated carbon-carbon bonds in the aliphatic acid component of the oil by atmospheric oxygen. When applied to a surface as a thin liquid layer of formulated alkyd coating, the cured films that form are relatively hard, non-melting, and substantially insoluble in many organic solvents that act as solvents or thinners for the unoxidized alkyd resin or drying oil. Such drying oils have been used as raw materials for oil-based coatings and are described in the literature.
[0044] By the term “urethane coating” as used hereinafter is meant a conventional liquid coating based on Type I urethane resins, typically a paint, clear coating, or stain. Urethane coatings typically contain the reaction product of a polyisocyanate, usually toluene diisocyanate, and a polyhydric alcohol ester of drying oil acids. Urethane coatings are classified by ASTM D-1 into five categories. Type I urethane coatings contain a pre-reacted autoxidizable binder as described in Surface Coatings Vol. I, previously cited. These are also known as uralkyds, urethane-modified alkyds, oil-modified urethanes, urethane oils, or urethane alkyds, are the largest volume category of polyurethane coatings and include paints, clear coatings, or stains. The cured coating is formed by air oxidation and polymerization of the unsaturated drying oil residue in the binder.
[0045] By the term “unsaturated polyester coating” as used hereinafter is meant a conventional liquid coating based on unsaturated polyester resins, dissolved in monomers and containing initiators and catalysts as needed, typically as a paint, clear coating, or gel coat formulation. Unsaturated polyester resins contain as the unsaturated prepolymer the product obtained from the condensation polymerization of a glycol such as 1,2-propylene glycol or 1,3-butylene glycol with an unsaturated acid such as maleic (or of maleic and a saturated acid, e.g., phthalic) in the anhydride form. The unsaturated prepolymer is a linear polymer containing unsaturation in the chain. This is dissolved in a suitable monomer, for instance styrene, to produce the final resin. The film is produced by copolymerization of the linear polymer and monomer by means of a free radical mechanism. The free radicals can be generated by heat, or more usually by addition of a peroxide, such as benzoyl peroxide, separately packaged and added before use. Such coating compositions are frequently termed “gel coat” finishes. In order that curing can take place at room temperature, the decomposition of peroxides into free radicals is catalyzed by certain metal ions, usually cobalt. The solutions of peroxide and cobalt compound are added separately to the mix and well stirred before application. The unsaturated polyester resins that cure by a free radical mechanism are also suited to irradiation curing using, for instance, ultraviolet light. This form of cure, in which no heat is produced, is particularly suited to films on wood or board. Other radiation sources, for instance electron-beam curing, are also used.
[0046] By the term “water-dispersed coatings” as used herein is meant coatings intended for the decoration or protection of a substrate composed of water as an essential dispersing component such as an emulsion, latex, or suspension of a film-forming material dispersed in an aqueous phase. “Water-dispersed coating” is a general classification that describes a number of formulations and includes members of the above described classifications as well as members of other classifications. Water-dispersed coatings general contain other common coating ingredients. Water-dispersed coatings are exemplified by, but not limited to, pigmented coatings such as latex paints, unpigmented coatings such as wood sealers, stains, and finishes, coatings for masonry and cement, and water-based asphalt emulsions. A water dispersed coating optionally contains surfactants, protective colloids and thickeners, pigments and extender pigments, preservatives, fungicides, freeze-thaw stabilizers, antifoam agents, agents to control pH, coalescing aids, and other ingredients. For latex paints the film forming material is a latex polymer of acrylate acrylic, vinyl-acrylic, vinyl, or a mixture thereof. Such water-dispersed coating compositions are described by C. R. Martens in “Emulsion and Water-Soluble Paints and Coatings” (Reinhold Publishing Corporation, New York, N.Y., 1965).
[0047] By the term “dried coating” as used herein is meant the final decorative and/or protective film obtained after the coating composition has dried, set or cured. Such a final film can be achieved by, for non-limiting example, curing, coalescing, polymerizing, interpenetrating, radiation curing, UV curing or evaporation. Final films can also be applied in a dry and final state as in dry coating.
[0048] Blocking is the undesirable sticking together of two coated surfaces when pressed together, or placed in contact with each other for an extended period of time. When blocking occurs separation of the surfaces can result in disruption of the coating on one or both surfaces. Thus improved resistance to blocking is beneficial in many situations where two coated surfaces need to be in contact, for example on window frames.
[0049] The term “open time extension” is used herein to mean the time during which a layer of liquid coating composition can be blended into an adjacent layer of liquid coating composition without showing a lap mark, brush mark, or other application mark. It is also called wet-edge time. Latex paint containing low boiling volatile organic chemicals (VOC) has shorter than desired open-time due to lack of high boiling temperature VOC solvents. Lack of open time extension will cause surface defects such as overlapping brush marks or other marks. A longer open time extension is beneficial when the appearance of the coated surface is important, as it permits application of the coating without leaving overlap marks, brush marks, or other application marks at the area of overlap between one layer of the coating and an adjacent layer of the coating.
[0050] When used as additives the compositions of the present invention are effectively introduced to the coating base or other composition by thoroughly stirring it in at room or ambient temperature. More elaborate mixing can be employed such as using a mechanical shaker or providing heat or other methods. Such methods are not necessary and do not substantially improve the final composition.
[0051] When used as an additive to a coating base, the compositions of the invention generally are added at about 0.001 weight % to about 5 weight % based on solids (by weight based on solids of the additive in the paint). Preferably about 0.01 weight % to about 1 weight %, and more preferably 0.1 weight % to about 0.5 weight % is used.
[0052] The present invention also comprises substrates treated with the composition of the present invention. Suitable substrates include fibrous or hard surface substrates. The fibrous substrates include wood, paper, and leather. The hard surface substrates include porous and non-porous mineral surfaces, such as glass, stone, masonry, concrete, unglazed tile, brick, porous clay and various other substrates with surface porosity. Specific examples of such substrates include unglazed concrete, brick, tile, stone, granite, limestone, marble, grout, mortar, statuary, monuments, wood, composite materials such as terrazzo, and wall and ceiling panels including those fabricated with gypsum board. These are used in the construction of buildings, roads, parking ramps, driveways, floorings, fireplaces, fireplace hearths, counter tops, and other decorative uses in interior and exterior applications.
[0053] The compositions of the present invention are useful to provide one or more of water repellency, oil repellency, and stain resistance to treated substrates. The compositions of the present invention are also useful to provide oil repellency, resistance to blocking, and open time extension to substrates coated with a coating composition to which the composition of the present invention has been added. These properties are obtained using lower fluorine concentrations compared with conventional perfluorocarbon surface treatment agents, providing improved “fluorine efficiency” in the protection of treated surfaces. The compositions of the present invention are effective at fluorine concentrations about one half to one third of the fluorine concentration for conventional fluorochemical surface protectants. The compositions of the present invention also allow for the use of shorter fluoroalkyl groups containing 7 or fewer carbon atoms while conventional commercially available surface treatment products typically show poor oil repellency and water repellency performance if the fluoroalkyl groups contain less 8 carbon atoms.
Test Methods
[0054] The following test methods were used in the Examples herein.
Test Method 1—Repellency for Paper
[0055] The oil repellency of paper samples were tested by using the AATCC Kit Test Procedure (118-1997). Each test specimen was placed on a clean flat surface, test side up, being careful not to touch the area to be tested. From a height of about one inch (2.5 cm), a drop of test solution from an intermediate Kit Number testing bottle was dropped onto the test area. A stop watch was started as the drop was applied. After exactly 15 seconds, the excess fluid was removed with a clean swatch of cotton tissue and the wetted area was immediately examined. Failure was evidenced by a pronounced darkening of the specimen caused by penetration, even in a small area, under the drop. The procedure was repeated as required, making sure that drops from other Kit Number bottles fell in untouched areas. The Results were reported as the Kit Rating, which was the highest numbered solution that stood on the surface of the specimen for 15 seconds without causing failure. Thus higher numbers indicate superior performance. The average Kit Rating of five specimens to the nearest 0.5 number was reported.
[0000]
TABLE 1
The composition of AATCC Kit test solution (Tappi Kit Test Solution)
Rating Number
Composition Results
0
The test sample fails
Kaydol*
1
Passes Kaydol*
2
Passes 65:35 (v/v)
Kaydol:n-hexadecane
3
Passes n-hexadecane
4
Passes n-tetradecane
5
Passes n-dodecane
6
Passes n-decane
7
Passes n-octane
8
Passes n-heptane
*Kaydol is a light mineral oil available from Psaltz & Bauer, Inc., Waterbury, CT.
Test Method 2—Blocking Resistance of Architectural Latex Paints
[0056] The test method described herein is a modification of ASTM D4946-89—Standard Test Method for Blocking Resistance of Architectural Paints, which is hereby specifically incorporated by reference.
[0057] The face-to-face blocking resistance of paints to be tested was evaluated in this test. Blocking, for the purpose of this test, is defined as the undesirable sticking together of two painted surfaces when pressed together or placed in contact with each other for an extended period of time.
[0058] The paint to be tested was cast on a polyester test panel using an applicator blade. All painted panels were protected from grease, oil, fingerprints, dust, et cetera, to avoid surface contamination that could affect blocking resistance results. Typically, results are evaluated at 24 hours after casting the paint. After the panels have been conditioned in the conditioned room as specified in the ASTM Method referenced above for the desired period of time, six squares (3.8 cm×3.8 cm) were cut out from the painted test panel. The cut sections (three pairs) were placed with the paint surfaces face-to-face for each of the paints to be tested. The cut sections (three pairs) are placed with the paint surfaces face-to-face for each of the paints to be tested. The face-to-face specimens were placed in a 50° C. oven on a marble tray. A no. 8 stopper was placed on top, with the smaller diameter in contact with the specimens, and then a 1000 g weight was placed on top of the stopper. This resulted in a pressure of 1.8 psi (12.4×10 3 Pa) on the specimens. One weight and stopper was used for each specimen tested. After exactly 30 minutes, the stoppers and weights were taken off the test specimens which were removed from the oven and allowed to cool in the conditioned room for 30 minutes before determining resistance to blocking.
[0059] After cooling, the specimens were separated by peeling apart with a slow and steady force. The blocking resistance was rated from 0 to 10, corresponding to a subjective tack assessment (sound made upon separation of the painted specimens) or seal (complete adhesion of the two painted surfaces) as determined by the operator of the method. The specimen was put near the ear to actually hear the degree of tack. The rating system is described in Table 1. The degree of seal was estimated from the appearance of the specimens and the fraction of the paint surfaces that adhere. Paint tearing away from the test panel backing was an indication of seal. A higher number indicates better resistance to blocking.
[0000]
TABLE 2
Blocking Resistance Numerical Ratings
Blocking Resistance
Description of the
Performance
Numerical Ratings
Separation
Description
10
No tack
Perfect
9
Trace tack
Excellent
8
Very slight tack
Very good
7
Slight tack
Good/very good
6
Moderate to slight tack
Good
5
Moderate tack
Fair
4
Very tacky - no seal
Poor to fair
3
5 to 25% seal
Poor
2
25 to 50% seal
Poor
1
50 to 75% seal
Very poor
0
75 to 100% seal
Very poor
Test Method 3—Surface Tension Measurement
[0060] Surface tension is measured using a Kruess Tensiometer, K11 Version 2.501 in accordance with instructions with the equipment. The Wilhelmy Plate method is used. A vertical plate of known perimeter is attached to a balance, and the force due to wetting is measured. 10 replicates are tested of each dilution, and the following machine settings are used:
Method: Plate Method SFT
Interval: 1.0 s
[0061] Wetted length: 40.2 mm
Reading limit: 10
Min Standard Deviation: 2 dynes/cm
Gr. Acc.: 9.80665 m/ŝ2
Test Method 4—Contact Angle Measurement
[0062] Contact angles are measured by the Sessile prop Method, which is described by A. W. Adamson in The Physical Chemistry of Surfaces, Fifth Edition, Wiley & Sons, New York, N.Y., 1990. Additional information on the equipment and procedure for measuring contact angles is provided by R. H. Dettre et al. in “Wettability”, Ed. by J. C. Berg, Marcel Dekker, New York, N.Y., 1993.
[0063] In the Sessile prop Method, a Ramè-Hart optical bench (available from Ramè-Hart Inc., 43 Bloomfield Ave., Mountain Lakes, N.J.) is used to hold the substrate in the horizontal position. The contact angle is measured at a prescribed temperature with a telescoping goniometer from the same manufacturer. A drop of test liquid is placed on a polyester scrub test panel (Leneta P-121 dull black or equivalent, Leneta Company, Mahwah, N.J.) and the tangent is precisely determined at the point of contact between the drop and the surface. An advancing angle is determined by increasing the size of the drop of liquid and a receding angle is determined by decreasing the size of the drop of liquid. The data are presented typically as advancing and receding contact angles.
[0064] The relationship between water and organic liquid contact angles, and the cleanability and dirt retention of surfaces is described by A. W. Adamson, above. In general, higher hexadecane contact angles indicate that a surface has greater dirt and soil repellency, and easier surface cleanability.
[0065] The water and hexadecane advancing angles of the dried coating compositions containing a composition of the present invention as an additive were measured on coatings cast on the Leneta panels, available from The Leneta Company, Mahwah, N.J.
Test Method 5—Open-Time Extension
[0066] Open-time is time during which a layer of applied liquid coating composition can be blended into an adjacent layer of liquid coating composition without showing a lapmark, brush mark, or other application mark. It is also called wet-edge time. Low VOC latex paint has shorter than desired open-time due to lack of high boiling temperature VOC solvents. Lack of sufficient open-time will result in overlapping brush marks or other marks. Open-time testing is conducted by a well accepted industry practice, called thumb press method as described herein. A double strip drawn down panel of the control sample and the sample with 0.1% active ingredient of the sample to be tested are employed. The coating composition to be tested and the control are the same coating composition wherein the control contains no additive to be tested, and the sample to be tested contains a composition of the present invention as an additive. The panel is made with a 7 cm doctor blade at 20-25° C. and 40-60% relative humidity. A double thumb press with equal pressure is then applied to each sample side by side at 1-2 minute intervals. The end point is when no paint residue on the thumb is observed. The time from when the drawdown is made to the end point is recorded as open-time. The percent difference between the control and the sample containing a composition of the present invention as an additive is recorded as the percent open-time extension. Compositions of the present invention were tested in a semi-gloss latex paint and a matte finish paint.
Test Method 6—Determination of Water and Oil Repellency
[0067] This test method describes the procedure for testing water repellency on hard surface substrates including limestone, concrete, granite, and saltillo. Square tiles of 12 inch square (30.5 cm 2 ) of a sample limestone (Euro Beige), and granite (White cashmere) were cut into 4 inch (10.2 cm) by 12 inch (30.5 cm) samples. Concrete bricks employed were 7.5 inch (19 cm) by 3.5 inch (9 cm), and saltillo pavers employed were 12-inch square (30.5 cm 2 ) were employed. After cutting, the samples were rinsed to remove any dust or dirt and allowed to dry thoroughly, typically for at least 24 hours. A penetrating solution was prepared by mixing a composition of the present invention with deionized water, with mixing, to provide a fluorine concentration of 0.8% fluorine by weight. A ½-inch (1.3 cm) paintbrush was used to apply the solution to samples of each substrate surface. The surface was then allowed to dry for fifteen minutes. If necessary, the surface was wiped with a cloth soaked in the treating solution to remove any excess. After the treated substrates dried overnight, three drops of deionized water and three drops of Canola oil were placed on each substrate and allowed to sit for five minutes. Visual contact angle measurements were used to determine water and oil repellency. The following rating chart was used to determine contact angle using a 0 to 5 scale, as shown below:
[0000] Repellency Rating 5 (Excellent): Contact angle 100°-120°.
Repellency Rating 4 (Very good): Contact angle 75°-90°.
Repellency Rating 3 (Good): Contact angle 45°-75°.
Repellency Rating 2 (Fair): Contact angle 25°-45°.
Repellency Rating 1 (Poor): Contact angle 10°-25°.
Repellency Rating 0 (Penetration): Contact angle<10°.
[0068] Higher numbers indicate greater repellency with ratings of 2 to 5 being acceptable. The data is reported in the tables as water beading and oil beading.
Test Method 7—Determination of Stain Resistance
[0069] Stain resistance was determined on limestone, concrete and Saltillo substrates using this method. Square tiles of 12 inch square (30.5 cm 2 ) of a sample limestone (Euro Beige) were cut into 4 inch (10.2 cm) by 12 inch (30.5 cm) samples. Concrete bricks employed were 7.5 inch (19 cm) by 3.5 inch (9 cm), and saltillo pavers employed were 12-inch square (30.5 cm 2 ) were employed. After cutting, the samples were rinsed to remove any dust or dirt and allowed to dry thoroughly, typically for at least 24 hours. A penetrating solution was prepared by mixing the composition of the present invention with deionized water to provide a concentration of 0.8% fluorine by weight. A ½-inch (1.3 cm) paintbrush was used to apply the solution to samples of each substrate surface. The surface was then allowed to dry for fifteen minutes. If necessary, the surface was wiped with a cloth soaked in the treating solution to remove any excess. After the treated substrates dried overnight, the following food stains were placed at intervals on the surface of the substrate: 1) hot bacon grease, 2) cola, 3) black coffee, 4) grape juice, 5) Italian salad dressing, 6) ketchup, 7) lemon juice, 8) mustard, 9) canola oil and 10) motor oil. After a 24-hour period, the food stains were blotted or lightly scraped from the substrate surface. The substrate's surface was rinsed with water and a 1% soap solution, and a stiff bristle brush was used to scrub the surface 10 cycles back and forth. The substrates were then rinsed with water and allowed to dry for 24 hours before rating.
[0070] The stains remaining on the tile surfaces after cleaning were rated visually according to a scale of 0 to 4 as follows: 0=no stain; 1=very light stain; 2=light stain; 3=moderate stain; and 4=heavy stain. The ratings for each substrate type are summed for each of the stains to give a composite rating for each type. The maximum total score for one substrate was 10 stains times the maximum score of 4=40. Lower scores indicated better stain protection, with scores of 20 or less being acceptable and with zero indicating the best protection with no stain present.
EXAMPLES
Example 1
[0071] C 3 F 7 OCF 2 CF 2 I (100 g, 0.24 mol) and benzoyl peroxide (3 g) were charged under nitrogen into a vessel. A series of three vacuum/nitrogen gas sequences was then executed at −50° C. and ethylene (18 g, 0.64 mol) was introduced. The vessel was heated for 24 hour at 110° C. The autoclave was cooled to 0° C. and opened after degassing. Then the product was collected in a bottle. The product was distilled giving 80 g of C 3 F 7 OCF 2 CF 2 CH 2 CH 2 I in 80% yield. The boiling point was 56˜60° C. at 25 mm Hg pressure (3325 Pa).
[0072] A mixture of C 3 F 7 OCF 2 CF 2 CH 2 CH 2 I (300 g, 0.68 mol) and N-methyl-formamide (300 mL), was heated to 150° C. for 26 hours. Then the reaction was cooled to 100° C., followed by the addition of water to separate the crude ester. Ethyl alcohol (77 mL) and p-toluene sulfonic acid (2.59 g) were added to the crude ester, and the reaction was stirred at 70° C. for 15 minutes. Then ethyl formate and ethyl alcohol were distilled out to give a crude product. The crude product was dissolved in ether, washed with aqueous sodium sulfite, water, and brine in turn, then dried over magnesium sulfate. The product was then distilled to give 199 g of C 3 F 7 OCF 2 CF 2 CH 2 CH 2 OH in 85% yield. The boiling point is 71˜73° C. at 40 mmHg (5320 Pa).
[0073] Phosphorous pentoxide (2.87 g) (0.02 mols) was added to 20 g (0.06 mols) of C 3 F 7 OCF 2 CF 2 CH 2 CH 2 OH at 85° C. and the reaction was heated to 100° C. After 16 hours, 34 mL of isopropyl alcohol was added to the reaction mixture at 85° C., stirred for 30 minutes, followed by the addition of 43 mL of DI water. After 1.5 hours, 5.93 mL (0.06 mols) of diethanolamine was added and the reaction was stirred for 2 hours at 65° C. to provide the diethanolamine salt of the resulting polyfluoropolyether-based phosphate of formula (I) wherein j, q, and r were each 1, R f was n-C 3 F 7 .
[0074] The resulting product was applied to paper samples (white bleached 50# paper) for oil repellency testing using Test Method 1. Results are in Table 3. A penetrating solution was prepared containing a fluorine concentration of 0.8% fluorine by weight and was applied to limestone and concrete substrates as described in Test Methods 6 and 7. The substrate samples and untreated controls were tested for water repellency, oil repellency and stain resistance according to Test Methods 6 and 7. The test results are shown in Tables 4 and 5.
[0000] The product of this example was also tested for surface tension according to Test Method 3. The resulting data is in Table 9. The product of this example was added to semi-gloss latex paint, high gloss latex paint, and matte latex paint in an amount of 0.3% by weight. The contact angle was measured using Test Method 4 and the resulting data is in Tables 11 and 12. Resistance to blocking was measured according to Test Method 2 with results in Table 10. The product of this example was added to semi-gloss latex paint and matte latex paint in an amount of 0.1% by weight. Open time extension was measured using Test Method 5 with the resulting data in Tables 13A and 13B.
Example 2
[0075] C 2 F 5 OCF 2 CF 2 I (116 g, 0.32 mol) and benzoyl peroxide (4 g) were charged under nitrogen into a vessel. A series of three vacuum/N2 gas sequences was then executed at −50° C. and ethylene (24 g, 0.86 mol) was introduced. The vessel was heated for 24 hour at 110° C. The autoclave was cooled to 0° C. and opened after degassing. Then the product was collected in a bottle. Six runs were combined, and the product was distilled giving 470 g of C 2 F 5 OCF 2 CF 2 CH 2 CH 2 I in 64% yield. The boiling point was 75˜77° C. at 25 mm Hg pressure (3325 Pa).
[0076] The flask was charged with 130 g of C 2 F 5 OCF 2 CF 2 CH 2 CH 2 I, 643 mL of the methylpyrrolidinone and 48 mL of deionized (DI) water. The reaction mixture was heated to 132 C for 20 hours. DI water was added and the lower layer was separated. The lower layer was dissolved in ether, washed with saturated sodium sulfite, and dried over anhydrous sodium sulfate. After rotary vaporization, 48 g of C 2 F 5 OCF 2 CF 2 CH 2 CH 2 OH was obtained by distillation in 52% yield. The boiling point was 70˜72° C. at 60 mm Hg pressure (7980 Pa).
[0077] Phosphorous pentoxide (1.70 g) (0.012 mols) was added to 10 g (0.036 mols) of the C 2 F 5 OCF 2 CF 2 CH 2 CH 2 OH at 85° C. and reaction was heated to 100° C. After 16 hours, 20 mL of isopropyl alcohol was added to the reaction mixture at 85° C. stirred for 30 minutes, followed by the addition of 25.5 mL of DI water. After 1.5 hours, 3.86 g of diethanolamine was added and the reaction was stirred for 2 hours at 65° C. to provide the diethanolamine salt of the resulting polyfluoropolyether-based phosphate of formula (I) wherein j, q and r were each 1, R f was C 2 F 5 .
[0078] The resulting product was applied to paper samples (white bleached 50# paper) for oil repellency testing using Test Method 1. Results are in Table 3. A penetrating solution was prepared containing a fluorine concentration of 0.8% fluorine by weight and was applied to limestone and concrete substrates as described in Test Methods 6 and 7. The substrate samples and untreated controls were tested for water repellency, oil repellency and stain resistance according to Test Methods 6 and 7. The test results are shown in Tables 4 and 5.
[0000] The product of this example was also tested for surface tension according to Test Method 3. The resulting data is in Table 9. The product of this example was added to semi-gloss latex paint, high gloss latex paint, and matte latex paint in an amount of 0.3% by weight. The contact angle was measured using Test Method 4 and the resulting data is in Tables 11 and 12. Resistance to blocking was measured according to Test Method 2 with results in Table 10. The product of this example was added to semi-gloss latex paint and matte latex paint in an amount of 0.1% by weight. Open time extension was measured using Test Method 5 with the resulting data in Table 13A.
Example 3
[0079] CF 3 OCF 2 CF 2 I (285 g, 0.91 mol) and benzoyl peroxide (12 g) were charged under nitrogen into a vessel. A series of three vacuum/nitrogen gas sequences were then executed at −50° C., after which ethylene (69 g, 2.46 mol) was introduced. The vessel was heated for 24 hours at 110° C. The autoclave was cooled to 0° C. and opened after degassing. Then the product was collected in a bottle. Two runs were combined and the product was distilled giving 292 g of CF 3 OCF 2 CF 2 CH 2 CH 2 I in 50% yield. The boiling point of the product was 56˜60° C. at 60 mmHg pressure (7980 Pa).
[0080] A mixture of CF 3 OCF 2 CF 2 CH 2 CH 2 I, (92 g, 0.27 mol) and N-methyl-formamide (119 mL), was heated to 150° C. for 26 hours. Then the reaction was cooled to 100° C., followed by the addition of water to separate the crude ester. Ethyl alcohol (30 mL) and p-toluene sulfonic acid (1.03 g) were added to the crude ester, and the reaction was stirred at 70° C. for 15 minutes. Then ethyl formate and ethyl alcohol were distilled out to give a crude product. The crude product was dissolved in ether, washed with aqueous sodium sulfite, water, and brine in turn, then dried over magnesium sulfate. The product was then distilled to give 44 g of CF 3 OCF 2 CF 2 CH 2 CH 2 OH in 71% yield.
[0081] Phosphorous pentoxide (2.06 g) (0.0145 mols) was added to 10 g (0.0435 mols) of CF 3 OCF 2 CF 2 CH 2 CH 2 OH at 85° C. and the reaction was heated to 100° C. After 16 hours, 34 mL of isopropyl alcohol was added to the reaction mixture at 85° C., stirred for 30 minutes, followed by the addition of 31 mL of DI water. After 1.5 hours, 4.67 g (0.044 mols) DEA was added and the reaction was stirred for 2 hours at 65° C. to provide the diethanolamine salt of the resulting polyfluoropolyether-based phosphate of formula (I) wherein j, q and r were each 1, R f was CF 3 .
[0082] The resulting product was applied to paper samples (white bleached 50# paper) for oil repellency testing using Test Method 1. Results are in Table 3. A penetrating solution was prepared containing a fluorine concentration of 0.8% fluorine by weight and was applied to limestone and concrete substrates as described in Test Methods 6 and 7. The substrate samples and untreated controls were tested for water repellency, oil repellency and stain resistance according to Test Methods 6 and 7. The test results are shown in Tables 4 and 5. The product of this example was added to semi-gloss latex paint, high gloss latex paint, and matte latex paint in an amount of 0.3% by weight. The contact angle was measured using Test Method 4 and the resulting data is in Tables 11 and 12. Resistance to blocking was measured according to Test Method 2 with results in Table 10. The product of this example was added to semi-gloss latex paint and matte latex paint in an amount of 0.1% by weight. Open time extension was measured using Test Method 5 with the resulting data in Table 13A.
Comparative Example A
[0083] The procedure of Example 1 was employed, but using the same equivalents of a fluorochemical prepared from a perfluoroalkylethyl alcohol mixture of the formula F(CF 2 ) a CH 2 CH 2 OH, with and average molecular weight of 471 wherein a ranged from 6 to 14, and was predominately 6, 8, and 10. The typical mixture was as follows: 27% to 37% of a=6, 28% to 32% of a=8, 14% to 20% of a=10, 8% to 13% of a=12, and 3% to 6% of a=14. This compound is commercially available from E. I. du Pont de Nemours and Company, Wilmington, Del. The resulting product was applied on paper samples and tested for oil repellency using Test Method 1 as in Example 1. Resulting data are in Table 3.
[0000]
TABLE 3
Oil Repellency on Paper
Phosphate
Fluorine
Example
g/m 2
g/m 2
Repellency
Untreated
0
0
0
control
1
0.293
0.133
4
2
0.293
0.122
2
3
0.293
0.111
2
Comparative A
0.293
0.155
3
1
0.586
0.265
5
2
0.586
0.244
5
3
0.586
0.222
4
Comparative A
0.586
0.308
5
[0084] The data in Table 3 demonstrates that the above Examples 1 to 3 provided excellent oil repellency when applied to a paper substrate. The repellency was comparable to Comparative Example A, but Examples 1 to 3 contained a lower level of fluorine to generate this performance.
[0000]
TABLE 4
Tests Results on Limestone
Example
1
2
3
Control
% F in solution
0.8
0.8
0.8
0
Amount Applied
0.47
0.48
0.46
0
(g/m 2 )
Food stains
Coke
1
1
2
3
Mustard
3
2
2
3
Ketchup
1
1
2
2
Grape juice
1
1
2
3
Italian dressing
1
2
1
3
Coffee
3
3
2
3
Lemon Juice
4
4
4
4
Motor Oil
1
1
1
4
Canola Oil
0
1
1
4
Bacon Grease
0
1
1
4
Total
15
17
18
33
Water Beading
2
2
2
1
Oil Beading
4
4
4
1
[0000]
TABLE 5
Tests Results on Concrete
Example
1
2
3
Control
% F in solution
0.8
0.8
0.8
0
Amount Applied
3.37
3.22
3.25
0
(g/m 2 )
Food stains
Coke
1
1
3
3
Mustard
2
3
2
4
Ketchup
1
1
1
4
Grape juice
2
3
3
4
Italian dressing
0
2
1
4
Coffee
2
2
3
3
Lemon Juice
3
3
2
3
Motor Oil
3
3
2
4
Canola Oil
3
2
2
4
Bacon Grease
4
4
3
4
Total
21
24
22
37
Water Beading
4
3
3
1
Oil Beading
4
4
4
0
[0085] The data in Tables 4 and 5 show improved resistance to staining for limestone and concrete treated with the composition of the present invention for Examples 1 to 3 for various food stains compared to an untreated control. Water repellency and oil repellency were also demonstrated and are noted in the Table as Oil Beading and Water Beading.
Example 4
[0086] Phosphorous pentoxide (1.87 g, 0.013 mols) was added to 10 g (0.03 mols) of C 3 F 7 OCF 2 CF 2 CH 2 CH 2 OH prepared as in Example 1 at 85° C. and reaction was heated to 100° C. After 14 hours, 10 mL of isopropyl alcohol was added to the reaction mixture at 65° C., stirred for 1 hour at 50° C. followed by the addition of 12.6 mL of DI water. After 5 minutes, 2 mL ammonia (30% aqueous solution) (0.029 mols) was added and the reaction was stirred for 1 hour at 32° C. to provide the ammonium salt of the resulting polyfluoropolyether phosphate of formula (I) wherein j, q and r were each 1, R f was C 3 F 7 . 31 P NMR of the final product showed 46.6 mol % bis(fluoroalkyl)phosphate (x=2) 34.6 mol % fluoroalkylphosphate (x=1) and minor amounts of several other components including phosphate.
[0087] A penetrating solution was prepared containing a fluorine concentration of 0.8% fluorine by weight and was applied to limestone, saltillo and granite substrates as described in Test Methods 6 and 7. The substrate samples and untreated controls were tested for water repellency and oil repellency using Test Method 6 and stain resistance according to Test Method 7. The test results are shown in Tables 6, 7 and 8. The product of this example was also tested for surface tension according to Test Method 3. The resulting data is in Table 9. The product of this example was added to semi-gloss latex paint, high gloss latex paint, and matte latex paint in an amount of 0.3% by weight. The contact angle was measured using Test Method 4 and the resulting data is in Tables 11 and 12. Resistance to blocking was measured according to Test Method 2 with results in Table 10. The product of this example was added to semi-gloss latex paint and matte latex paint in an amount of 0.1% by weight. Open time extension was measured using Test Method 5 with the resulting data in Tables 13A and 13B.
Example 5
[0088] Phosphorous pentoxide (1.11 g) (0.008 mols) was added to 5 g (0.018 mols) of C 2 F 5 OCF 2 CF 2 CH 2 CH 2 OH prepared as in Example 2 at 85° C. and reaction was heated to 100° C. After 14 hours, 6 mL of isopropyl alcohol was added to the reaction mixture at 65° C., stirred for 1 hour at 50° C. followed by the addition of 7.6 mL of DI water. After 5 minutes, 1.2 mL ammonia (30% aqueous solution) (0.017 mols) was added and the reaction was stirred for 1 hour at 32° C. to provide the ammonium salt of the resulting polyfluoropolyether phosphate of formula (I) wherein j, q and r were each 1, and R f was C 2 F 5 . 31 P NMR of the final product showed 47.5 mol % bis(fluoroalkyl)phosphate (x=2) 30.1 mol % fluoroalkylphosphate (x=1) and minor amounts of several other components including phosphate.
[0089] A penetrating solution was prepared containing a fluorine concentration of 0.8% fluorine by weight and was applied to limestone, saltillo and granite substrates as described in Test Methods 6 and 7. The substrate samples and untreated controls were tested for water repellency and oil repellency using Test Method 6 and stain resistance according to Test Method 7. The test results are shown in Tables 6, 7 and 8. The product of this example was also tested for surface tension according to Test Method 3. The resulting data is in Table 9. The product of this example was added to semi-gloss latex paint, high gloss latex paint, and matte latex paint in an amount of 0.3% by weight. The contact angle was measured using Test Method 4 and the resulting data is in Tables 11 and 12. Resistance to blocking was measured according to Test Method 2 with results in Table 10. The product of this example was added to semi-gloss latex paint and matte latex paint in an amount of 0.1% by weight. Open time extension was measured using Test Method 5 with the resulting data in Table 13A.
Example 6
[0090] Phosphorous pentoxide (1.34 g) (0.0095 mols) was added to 5 g (0.022 mols) of CF 3 OCF 2 CF 2 CH 2 CH 2 OH prepared as in Example 3 at 85° C. and reaction was heated to 100° C. After 14 hours, 7.1 mL of isopropyl alcohol was added to the reaction mixture at 65° C., stirred for 1 hour at 50° C. followed by the addition of 9 mL of DI water. After 5 minutes, 1.4 mL (0.021 mols) ammonia (30% aqueous solution) was added and the reaction was stirred for 1 hour at 32° C. to provide the ammonium salt of the resulting polyfluoropolyether phosphate of formula (I) wherein j, q and r were each 1, R f was CF 3 . 31 P NMR of the final product showed 45.5 mol % bis(fluoroalkyl)phosphate (x=2) 30.5 mol % fluoroalkylphosphate (x=1) and minor amounts of several other components including phosphate.
[0091] A penetrating solution was prepared containing a fluorine concentration of 0.8% fluorine by weight and was applied to limestone, saltillo and granite substrates as described in Test Methods 6 and 7. The substrate samples and untreated controls were tested for water repellency and oil repellency using Test Method 6 and stain resistance according to Test Method 7. The test results are shown in Tables 6, 7 and 8. The product of this example was added to semi-gloss latex paint, high gloss latex paint, and matte latex paint in an amount of 0.3% by weight. The contact angle was measured using Test Method 4 and the resulting data is in Tables 11 and 12. Resistance to blocking was measured according to Test Method 2 with results in Table 10. The product of this example was added to semi-gloss latex paint and matte latex paint in an amount of 0.1% by weight. Open time extension was measured using Test Method 5 with the resulting data in Table 13A.
[0000]
TABLE 6
Tests Results on Saltillo
Example
4
5
6
Control
% F in solution
0.8
0.8
0.8
0
Amount Applied (g/m 2 )
1.12
1.17
1.14
0
Food stains
Coke
1
1
0
0
Mustard
2
3
3
3
Ketchup
1
1
1
2
Grape juice
3
1
3
1
Italian dressing
2
1
2
4
Coffee
3
3
2
1
Lemon Juice
1
2
2
3
Motor Oil
1
2
1
4
Canola Oil
2
2
2
4
Bacon Grease
2
2
2
4
Total
18
18
18
26
Water Beading
¾
3
⅔
0
Oil Beading
4
4
4
0
[0000]
TABLE 7
Tests Results on Limestone
Example
4
5
6
Control
% F in solution
0.8
0.8
0.8
0
Amount Applied
0.5
0.48
0.48
0
(g/m 2 )
Food stains
Coke
1
0
2
2
Mustard
3
4
4
3
Ketchup
2
3
2
3
Grape juice
2
1
1
2
Italian dressing
1
2
2
4
Coffee
1
2
2
3
Lemon Juice
4
4
4
4
Motor Oil
0
1
0
4
Canola Oil
0
0
0
4
Bacon Grease
0
0
0
4
Total
14
17
17
33
Water Beading
4
4
3
1
Oil Beading
¾
4
4
1
[0000]
TABLE 8
Tests Results on Granite
Example
4
5
6
Control
% F in soln
0.8
0.8
0.8
0
Amt. Applied
0.35
0.41
0.39
0
(g/m 2 )
Food stains
Coke
0
0
0
2
Mustard
0
0
0
3
Ketchup
0
0
0
2
Grape juice
0
0
0
3
Italian dressing
0
0
0
3
Coffee
0
0
0
3
Lemon Juice
0
0
0
2
Motor Oil
0
0
0
3
Canola Oil
0
0
0
3
Bacon Grease
0
0
0
3
Total
0
0
0
27
Water Beading
⅔
2
3
1
Oil Beading
3
3
3
2
[0092] The data in Tables 6, 7 and 8 demonstrates that Examples 4, 5 and 6 of the present invention provided a significant improvement in overall stain resistance versus untreated control for limestone, saltillo and granite substrates for a variety of food stains. Resistance to both oil and water based stains was demonstrated on a variety of substrates, thus demonstrating the efficacy as a hard porous surface protective sealer. The data also demonstrates that the Examples 4, 5 and 6 provided significant improvement to water and oil repellency.
Example 7
[0093] Phosphorous pentoxide (0.95 g) (0.0067 mols) was added to 5 g (0.015 mols) of C 3 F 7 OCF 2 CF 2 CH 2 CH 2 OH prepared as in Example 1 at 85° C. and reaction was heated to 105° C. After 14 hours, 12.5 g of ethylene glycol (EG) was added to the reaction mixture at 95° C., stirred for 25 minutes, followed by the addition of TERGITOL 15-S-9 available from Sigma Aldrich, St. Louis, Mo. (1.16 g) at 86° C. After 10 minutes, 0.95 mL (0.0153 mols) ammonia (30% aqueous solution) was added and the reaction was stirred for 10 minutes at 70° C. Finally 30 mL water was added and the reaction was stirred at 70° C. for 1 hour, and the 1.3 mL ammonia (30% aqueous solution) was injected to adjust pH to 9.8 to provide the ammonium salt of the resulting polyfluoropolyether phosphate of formula (I) wherein j, q and r were each 1, and R f was C 3 F 7 .
[0094] The product of this example was tested for surface tension according to Test Method 3. The resulting data is in Table 9. The product of this example was added to semi-gloss latex paint, high gloss latex paint, and matte latex paint in an amount of 0.3% by weight. The contact angle was measured using Test Method 4 and the resulting data is in Tables 11 and 12. Resistance to blocking was measured according to Test Method 2 with results in Table 10. The product of this example was added to semi-gloss latex paint and matte latex paint in an amount of 0.1% by weight. Open time extension was measured using Test Method 5 with the resulting data in Table 13A.
Example 8
[0095] Phosphorous pentoxide (1.15 g) (0.0081 mols) was added to 5 g (0.018 mols) of C 2 F 5 OCF 2 CF 2 CH 2 CH 2 OH prepared as in Example 2 at 85° C. and reaction was heated to 105° C. After 14 hours, 15 g of ethylene glycol was added to the reaction mixture at 95° C., stirred for 25 minutes, followed by the addition of TERGITOL 15-S-9 available from Sigma Aldrich, St. Louis, Mo. (1.37 g) at 86° C. After 10 minutes, 1.14 mL (0.018 mols) ammonia (30% aqueous solution) was added and the reaction was stirred for 10 minutes at 70° C. Finally 36 mL water was added and the reaction was stirred at 70° C. for 1 hour, and the 1.6 mL ammonia (30° A) aqueous solution) was injected to adjust pH to 9.8 to provide the ammonium salt of the resulting polyfluoropolyether phosphate of formula (I) wherein j, q and r were each 1, R f was C 2 F 5 .
[0096] The product of this example was tested for surface tension according to
[0097] Test Method 3. The resulting data is in Table 9. The product of this example was added to semi-gloss latex paint, high gloss latex paint, and matte latex paint in an amount of 0.3% by weight. The contact angle was measured using Test Method 4 and the resulting data is in Tables 11 and 12. Resistance to blocking was measured according to Test Method 2 with results in Table 10. The product of this example was added to semi-gloss latex paint and matte latex paint in an amount of 0.1% by weight. Open time extension was measured using Test Method 5 with the resulting data in Table 13A.
Example 9
[0098] Phosphorous pentoxide (1.41 g) (0.001 mols) was added to 5 g (0.022 mols) of CF 3 OCF 2 CF 2 CH 2 CH 2 OH prepared as in Example 3 at 85° C. and reaction was heated to 105° C. After 14 hours, 18.32 g of ethylene glycol was added to the reaction mixture at 95° C., stirred for 25 minutes, followed by the addition of TERGITOL 15-S-9 available from Sigma Aldrich, St. Louis, Mo. (1.16 g) at 86° C. After 10 minutes, 1.4 mL (0.022 mols) ammonia (30% aqueous solution) was added and the reaction was stirred for 10 minutes at 70° C. Finally 43 mL water was added and the reaction was stirred at 70° C. for 1 hour, and the 3.0 mL ammonia (30% aqueous solution) was injected to adjust pH to 9.8 to provide the ammonium salt of the resulting polyfluoropolyether phosphate of formula (I) wherein j, q and r were each 1, R f was CF 3 .
[0099] The product of this example was added to semi-gloss latex paint, and high gloss latex paint in an amount of 0.3% by weight. The contact angle was measured using Test Method 4 and the resulting data is in Tables 11 and 12. Resistance to blocking was measured according to Test Method 2 with results in Table 10. The product of this example was added to semi-gloss latex paint and matte latex paint in an amount of 0.1% by weight. Open time extension was measured using Test Method 5 with the resulting data in Table 13A.
Comparative Example B
[0100] The procedure of Example 4 was employed, but using as the fluorochemical a perfluoroalkylethyl alcohol mixture of the formula F(CF 2 ) a CH 2 CH 2 OH, wherein a ranged from 6 to 14, and was predominately 6, 8, and 10. The typical mixture was as follows: 27% to 37% of a=6, 28% to 32% of a=8, 14% to 20% of a=10, 8% to 13% of a=12, and 3% to 6% of a=14. The product was added to semi-gloss latex paint and high gloss latex paint in an amount of 0.03% by weight and tested for resistance to blocking using Test Method 2. Results are in Table 10. The product of this example was added to semi-gloss latex paint and matte latex paint in an amount of 0.1% by weight. Open time extension was measured using Test Method 5 with the resulting data in Table 13A.
Comparative Example C
[0101] The procedure of Example 7 was employed, but using as the fluorochemical a perfluoroalkylethyl alcohol mixture of the formula F(CF 2 ) a CH 2 CH 2 OH, wherein a ranged from 6 to 14, and was predominately 6, 8, and 10. The typical mixture was as follows: 27% to 37% of a=6, 28% to 32% of a=8, 14% to 20% of a=10, 8% to 13% of a=12, and 3% to 6% of a=14. The product was added to semi-gloss latex paint and high gloss latex paint in an amount of 0.03% by weight and tested for resistance to blocking using Test Method 2. Results are in Table 10. The product of this example was added to semi-gloss latex paint and matte latex paint in an amount of 0.1% by weight. Open time extension was measured using Test Method 5 with the resulting data in Table 13A.
[0000]
TABLE 9
Surface Tension (dynes/cm)
Example*
0.000%
0.001%
0.005%
0.010%
0.050%
0.100%
0.200%
0.500%
1
72.7
51.0
32.3
25.6
15.7
15.6
15.6
15.6
4
74.7
50.8
34.5
29.1
21.1
20.8
19.8
18.3
7
74.9
39.7
28.4
22.5
20.5
20.2
19.6
18.8
2
75.5
55.9
42.1
36.4
25.9
19.0
15.5
15.4
5
74.6
63.7
50.5
44.4
26.7
15.8
16.3
15.7
8
73.3
50.0
40.0
33.7
23.0
19.2
17.4
17.5
*Example was added to deionized water by weight based on solids of the additive in the paint.
*Standard Deviation <1 dynes/cm
*Temperature 25° C.
[0102] Normal surface tension of deionized water is 72 dyne/cm (shown in Table 9 as 0.000%). When each Example was added at a specified rate, the surface tension of each aqueous solution was reduced significantly. Better performance was obtained at higher levels. According to the results from these tests, excellent surface tension reduction was seen from all Examples of the present invention tested.
[0000]
TABLE 10
Resistance to Blocking in Semi-Gloss Latex Paint
Fluorine
Example*
Blocking Rating**
(micrograms/g)
Control
0.7
5
4
9.0
165
7
9.0
137
1
9.0
134
5
8.0
154
8
9.0
126
2
9.0
123
6
6.7
70
9
6.0
119
3
7.3
54
Comparative
5.0
153
Example B
Comparative
5.7
155
Example C
*Example was added to paint at 0.03% based on solids by weight based on solids of the additive in the paint
**Average of 3 replicates
[0103] The data in Table 10 demonstrates that excellent resistance to blocking was obtained from the examples of the present invention compared to Comparative Examples B and C.
[0000]
TABLE 11
Advancing Contact Angle in Semi-Gloss Latex Paint
Example*
Hexadecane
Control
28.07
1
76.13
4
75.10
7
77.03
2
76.80
5
77.20
8
77.23
3
73.47
6
72.93
9
72.20
*Example added to paint at 0.03% by weight based on solids of the additive in the paint
[0000]
TABLE 12
Advancing Contact Angle in High Gloss Latex Paint
Example*
Hexadecane
Control
5.3
1
60.7
4
68.0
7
63.7
2
54.5
5
61.3
8
52.2
3
30.5
6
36.0
9
24.9
*Example added to paint at 0.03% by weight based on solids of the additive in the paint
[0104] The data in Tables 11 and 12 show excellent increased hexadecane contact angle for all examples of the present invention compared to the control. The increase in the advancing hexadecane contact angle correlates with improved oil repellency.
[0000]
TABLE 13A
Semi-Gloss Latex Open-Time Extension
Open Time
Fluorine
Example
Extension (min)
% Extension
(ppm)
1
4.0
12.9%
435
2
8.0
21.1%
395
3
14.0
25.0%
168
4
4.0
13.3%
538
5
10.0
22.7%
502
6
16.0
25.8%
222
7
5.0
18.5%
445
8
12.0
24.0%
408
9
18.0
26.5%
385
Comparative
3
8.1%
498
Example B
Comparative
3
8.8%
505
Example C
*Example added to paint at 0.1% by weight based on solids of the additive in the paint
[0000]
TABLE 13B
Matte Latex Open-Time Extension
Open Time
Fluorine
Example
Extension (min)
% Extension
(ppm)
1
3.0
14.3%
435
4
2.0
8.7%
538
*Example added to paint at 0.1% by weight based on solids of the additive in the paint
[0105] The data in Tables 13A and 13B demonstrates that adding the Examples of the present invention to conventional paints increased the open time extension versus the same paint with no Example of the present invention added. The Examples 1 to 9 were superior to the Comparative Examples B and C. Also the Examples 1 to 9 contained a lower level of fluorine versus Comparative Examples B and C, yet provided superior open time extension, thus demonstrating increased fluorine efficiency.
|
A composition comprising one or more compounds of formula (I) or (II):
wherein:
R f is a linear or branched perfluoroalkyl having 1 to 7 carbon atoms, optionally interrupted by one to three oxygen atoms, r and q are each independently an integer of 1 to 3, j is 0 or 1, or a mixture thereof, x is from about 1 to about 2, Z is —O—, —S—, or —NR—, R is hydrogen or an alkyl group containing 1 to 4 carbon atoms X is hydrogen or M, and M is an ammonium ion, an alkali metal ion, or an alkanolammonium ion, and its use in providing surface properties to substrates is disclosed.
| 3
|
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an imaging equipment exploiting ultrasonic radiation, and more particularly to an acoustic microscope.
2. Description of the Prior Art
In recent years, it has become possible to generate and detect acoustic waves at ultra high frequencies reaching 1 GHz and therefore to realize an acoustic wavelength of approximatly 1 μm in the water. As a result, it has become possible to fabricate an acoustic imaging equipment of high resolution. The equipment forms a focused ultrasonic beam with a concave lens, thereby to realize the resolution as high as 1 μm.
A specimen is inserted in the beam, and an ultrasonic wave reflected by the specimen is detected, whereby the elastic properties of a very small area of the specimen are elucidated. Alternatively, while a specimen is being mechanically scanned in two dimensions, the intensity of the resulting signal is displayed as a brightness signal on a cathode-ray tube, whereby a very small area of the specimen can be observed on an enlarged scale.
First, a prior-art construction of such ultrasonic microscopic imaging equipment will be described, and a problem involved therein will be pointed out.
FIG. 1 is a view which shows the schematic construction of a prior art of a transducer system for obtaining a reflected signal from a specimen (as disclosed in, for example, U.S. Pat. No. 4,028,933). An ultrasonic propagating medium 20 (cylindrical crystal of, for example, sapphire or silica glass) has one end face 21 which is an optically polished plane, and the other end face which is formed with a concave semispherical hole 30. An RF pulse ultrasonic wave which is a plane wave is radiated into the crystal 20 by an RF pulse signal which is impressed on a piezoelectric film 10 deposited on the end face 21. The plane ultrasonic wave is focused on a specimen 50 located on a predetermined focal point, by a positive acoustic lens which is formed by the interface between the semispherical hole 30 and a medium 40 (in general, water).
The ultrasonic wave reflected and scattered by the specimen 50 is collected and converted into a plane wave by means of the same lens. The plane wave is propagated through the interior of the crystal 20, and is finally converted into an RF electric signal by the piezoelectric film 10. The RF electric signal is detected by a diode into a video signal, which is used as the input signal of the cathode-ray tube as stated above.
FIG. 2(a) shows detected signals in the video region at the time when, in such prior-art construction, an RF pulse signal having a certain repetition rate t R was impressed. Here, the axis of abscissas is a time axis and the axis of ordinates represents the intensity of the signal. Letter A designates the applied RF pulse, letter B a reflected signal from the lens boundary, and letter C a reflected signal from the specimen.
In order to discriminate the desired reflected signal C from the reflected signal B, the prior-art imaging equipment adopts a construction in which the duration t d of the impressed pulse is shortened to the utmost so as to prevent the signals C and B from overlapping each other, whereby only the signal C is taken out by a timing gate as shown in FIG. 2(c).
The resolutions of such equipment include an axial resolution Δζ in the direction of propagation of the ultrasonic wave, and a lateral resolution Δγ within a plane perpendicular to the propagating direction of the ultrasonic wave. Both are determined by the wavelength λ of the ultrasonic wave and the F number representative of the brightness of the lens used, and are given by:
Δγ=λ·F (1)
Δζ=2λ·F.sup.2 ( 2)
Since the F number of the lens which can be fabricated is approximately 0.7, Δγ˜1 μm and Δζ˜1.5 μm hold in the water (1,500 m/s) when the ultrasonic wave used is at 1 GHz.
However, an IC or LSI which is the most important object to-be-imaged of the ultrasonic microscope requires a better axial resolution. This is because, in the IC, a layered pattern is often finer than a planar pattern as is well known. In actuality, a typical IC has a multilayered structure consisting of layers 1 μm-3 μm thick. With the axial resolution of 2 μm in the water as above stated, it is utterly impossible that the layers are nondestructively observed independently of one another with the position of a focal point set inwardly of the surface of the IC. The reason is that, since the acoustic velocity is higher in a metal such as silicon and aluminum which is the material of the IC than in the water, the axial resolution is merely 4-10 μm even when the ultrasonic wave at 1 GHz is used.
SUMMARY OF THE INVENTION
An object of this invention is to provide an acoustic microscope which has an enhanced axial resolution.
In order to accomplish the object, this invention makes the duration of an RF pulse variable, so as to cause a reflected ultrasonic wave from a lens boundary to interfere with a reflected ultrasonic wave from a specimen.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view showing the schematic construction of a prior-art acoustic microscope,
FIGS. 2(a) to 2(f) are waveform diagrams for explaining the operation of the acoustic microscope and the principle of this invention,
FIG. 3 is a block diagram showing the construction of an embodiment of this invention, and
FIG. 4 is a block diagram for explaining a part of the embodiment in FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The principle of this invention consists in that, to the end of causing a reflected ultrasonic signal C from a specimen to interfere with a reflected ultrasonic signal B from the interface between a lens and water, the duration t d of an RF pulse is lengthened contrariwise to the case of the prior art.
Referring now to a waveform diagram shown in FIG. 2(d), the principle will be described.
As compared with the reflected signal B from the interface between the lens and the water, the reflected ultrasonic signal C from the specimen returns with a delay equal to a time interval 2 Z/V w (where Z denotes the spacing between the lens and the specimen, and V w the acoustic velocity in the water) in which the ultrasonic wave propagates reciprocatively between the lens and the specimen in the water. Therefore, when the duration t d of the RF pulse is made long as follows:
t.sub.d >2 Z/V.sub.w (≡t.sub.s) (3)
the two reflected signals come to overlap each other. The interference of the two reflected signals can be detected in such a way that the signals in the time range in which they overlap each other are taken out by a timing gate.
More specifically, when the reflected signal B from the interface between the lens and the water is put as follows:
V.sub.B (t)=A sin w.sub.o t, t.sub.o <t<t.sub.o +t.sub.d (4)
where w o denotes the frequency of the ultrasonic wave used, and t o =2 L/V L in which L indicates the length of the lens and V L the acoustic velocity in the material of the lens, the reflected ultrasonic signal C from the specimen is expressed by:
V.sub.C (t)=B sin w.sub.o (t+2 Z/V.sub.w), t.sub.o +t.sub.s <t<t.sub.o +t.sub.s +t.sub.d (5)
Therefore, the two signals overlap under the condition of Expression (3) and are expressed as V(t)=A sin w o t+B sin w o (t+2 Z/V w ) (hatched region in FIG. 2(d)) when:
t.sub.o +t.sub.s <t<t.sub.o +t.sub.d (6)
When they are subjected to the square law detection with a diode, they become in the video region as follows:
V(t)=A.sup.2 +B.sup.2 +2 A B cos (w.sub.o [2Z/V.sub.w ]) (7)
When the signals in the time range of Expression (6) are utilized, the following holds:
w.sub.o (2Z/V.sub.w)=2πZ/(λ/2) (8)
When the spacing Z between the lens and the specimen is changed in conformity with this expression, the detection signals are modulated at a period of λ/2. In other words, it becomes possible to detect the unevenness of the surface of the specimen or the layered structure within the specimen at a resolution of approximately λ/5 (modulation degree: 50%). This value λ/5 corresponds to the axial resolution λ (when F=0.7) in the prior-art method, and it turns out that the resolution is improved 5 times by the interference method.
When the ultrasonic wave of 1 GHz is used, the prior art attains only the axial resolutions of approximately 1.5 μm in the water and 8.4 μm in silicon (8,400 m/s), whereas this invention can make improvements to high axial resolutions of 0.3 μm in the water and 1.7 μm in silicon and permits for the first time the observation of the individual layers of the multilayered structure of the IC as stated in the beginning.
According to this invention, such interference method and the prior-art method are permitted to be properly used merely by changing-over the duration of the RF pulse signal by the use of an identical apparatus.
This is based on the fact that, as apparent from the above description, the two reflected ultrasonic signals B and C do not overlap each other when the duration t d of the RF pulse signal is made short as follows:
t.sub.d <2Z/V.sub.w (9)
FIG. 3 is a diagram which shows the construction of an embodiment of an apparatus for materializing this invention. Referring to the figure, numeral 100 designates an RF continuous wave oscillator, numeral 110 an analog switch, numeral 120 a directional coupler, numeral 130 a receiver amplifier, numeral 140 a diode detector, numeral 150 a timing-gate circuit, numeral 125 a transducer as shown in FIG. 1, numeral 160 a gate signal generator, and numeral 170 a change-over switch. In operation, an RF continuous wave signal (at, for example, 1 GHz) generated by the RF continuous wave oscillator 100 is turned by the analog switch 110 into an RF pulse signal of a duration t d , which is impressed on the transducer system (having the construction shown in FIG. 1) 125 through the directional coupler 120. Reflected detection signals are passed through the directional coupler 120 and amplified by the receiver amplifier 130. Thereafter, they are converted into video signals (having a band of approximately 10 MHz) by the diode detector 140, and only the desired signal is sampled as an imaging signal by the timing gate 150. In this case, in the present invention, the gate signal generator 160 is used for turning "on" and "off" the analog switch 110. A control signal for the analog switch 110 is generated from the gate signal generator 160 through the operation of the change-over switch 170. The control signal changes-over the analog switch 110 so as to establish t d >2 Z/V w being the condition of Expression (3) or t d <2 Z/W w being the condition of Expression (9). The construction and operation of an embodiment of the gate signal generator 160 for generating such changing-over control signal will now be described with reference to FIG. 4. Pulses having a repetition rate t R are generated by a pulse oscillator 161. In response to the rise of each of the pulses, pulses having durations Δt 1 , Δt 2 and Δt 3 are respectively formed by multivibrators 162a, 162b and 164. Here, the durations are selected to be Δt 1 <2 Z/V w , Δt 2 <2 Z/V w and Δt 3 =2 Z/V 2 +t s . Output waveforms of the multivibrators 162a and 162b (shown in FIGS. 2(b) and 2(e), respectively) are selected by a multiplexer 163, depending upon the logic high and low states of the switch 170. The selected signal is used as the control signal of the analog switch 110. More specifically, when the change-over switch 170 is connected on the side of a terminal H shown in FIG. 3, it lies in the logic high state (H in FIG. 4), and the multiplexer 163 selects the control signal of the waveform depicted in FIG. 2(d). On the other hand, when the change-over switch 170 is connected on the side of a terminal L shown in FIG. 3, it is in the logic low state (L in FIG. 4), and the multiplexer 163 selects the control signal of the waveform depicted in FIG. 2(e).
The output of the multivibrator 164 is applied to a multivibrator 165 again, thereby to form a pulse delayed Δt 3 . This pulse is used as the gate signal of the timing gate 150 (signal of a waveform depicted in FIG. 2(c) or 2(f)). the reflected signal from the specimen appears is not changed even by the change-over of the operation mode from the prior art to this invention or vice versa. Therefore, the same gate signal can be used advantageously.
As set forth above, according to this invention, the duration of the RF pulse is prolonged with reference to 2 Z/V w , whereby the interference method of this invention can be readily realized in the acoustic microscope. Therefore, this invention contributes greatly to the enhancements of performances such as the enhancement of the axial resolution, and it is powerful in the defect inspection and quality assurance of ICs and LSIs and very greatly contributive to the art.
Besides the case of obtaining the ultrasonic image with the acoustic microscope, this invention is applicable to the following measurements:
1 The measurement of the height of a sample surface as based on the detection of the unevenness of the sample surface; 2 the measurement of an acoustic velocity in an unknown fluid which exists between the lens and the sample, as based on the period (which is λ/2) of a pattern indicated by reflected signals obtained by changing the spacing between the lens and the sample; etc.
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In an acoustic microscope wherein a piezoelectric transducer disposed on one face of an ultrasonic wave focusing lens radiates an ultrasonic wave into the lens and also converts into an electric signal a reflected wave from a specimen arranged on the side of the other face of the lens, a reflected wave from the interface of the lens and the reflected wave from the specimen are caused to interfere with each other.
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BACKGROUND OF THE INVENTION
One of the uses for the recording material of the present invention is in laser beam recording.
Due to its coherence, the laser shows prospects of becoming a basic tool in the field of information transmission. As an energy source, it is compatible with intensity modulator requirements. Furthermore, electro-optical/mechanical deflection of laser radiation can be accomplished, with good positioning, at extremely high rates of speed.
It has been found possible, via the selective application of laser radiation, to create an image on a material adapted to receive the same. Basically, this is accomplished by positioning the material to receive the image adjacent to the coated surface of a thin film carrier, the coating being a transferable, colored, ink-like substance. When the uncoated surface of the carrier is irradiated with laser radiation, the portion of the colored coating opposite the irradiated area is transferred from the carrier to the receiving material.
In the past, recording material has been used which includes a binder since the binder was thought necessary to hold the colored substance on the carrier film. However, it was observed that the presence of the binder substantially reduced the speed of transfer of the recording material from the carrier substrate to the recording element. This, in turn, lowered the maximum recording speed below that ultimately desired.
Later it was found that increased recording speed could be achieved if a binderless coating of recording material was utilized, with the coating being deposited by an evaporation technique. But the evaporation method is relatively expensive and not suitable for coating long lengths of wide carrier tape.
It has now been found that quite satisfactory recording material for transfer recording, not only by laser beam, but also by other forms of energy absorption and even for contact printing, can be prepared by depositing a binderless coating of a suitable dye or pigment on a carrier substrate film from a solvent solution or suspension. Adherence to the substrate can be entirely adequate for the intended purpose and the coating can be made tough enough so that it does not readily rub off when subjected to ordinary handling.
Some publications which may be referred to for background information regarding the laser-writing technique, include:
Roshon, D. C., and Young, T., "Printing by Means of a Laser Beam," IBM Technical Disclosure Bulletin, Vol. 7, No. 3, August 1964;
Woodward, D. H., "Distillation Printing," IBM Technical Disclosure Bulletin, Vol. 9, No. 11, April 1967.
THE DRAWING
FIG. 1 is a block diagram of a laser recording apparatus;
FIG. 2 is an enlarged section view of the recording material portion of the apparatus of FIG. 1, and
FIG. 3 is the same view as FIG. 2 after transference of a portion of recording material.
DESCRIPTION OF PREFERRED EMBODIMENTS
First, a brief description will be given of one form of apparatus in which the recording material of the present invention is intended to be used. As shown in FIG. 1, a light modulator 12 accepts the laser beam 11 emitted by a laser 10 and modulates its intensity in response to the input signal 13 generated by signal processing means 14. The modulator 12 may be of the type which uses electro-optic crystals to effect the polarization of the laser beam as a direct function of the applied signal voltage. Polarization modulation is then converted into intensity modulation by a polarization analyzer attached to the modulator. Beam-enlargement and spot-forming optics, i.e. the imaging optics 16, then increases the diameter of the intensity modulated laser beam 15 until it fills the desired aperture of the imaging lens. The convergent cone of light 17 leaving the imaging lens may then be intercepted by a scanning mirror incorporated within the scanning mechanism 18. Scanning may be accomplished by rotating a multifaced mirror in precision air bearings with a direct-drive servo motor. Thus, the converging cone of light 19 directed by the scanning mechanism 18, is repetitively swung through an arc to produce an active scan on the uncoated surface 20 of a thin film substrate 21; the opposite surface of the substrate being coated with a vaporizable energy-absorbing dye 22. Spaced adjacent to the coated surface 22 of the substrate is a material 24 adapted to receive the transferred image created. As the uncoated surface 20 of the carrier is selectively irradiated by the intensity modulated beam 19, via the scanning mechanism 18, the coating opposite the irradiated area is transferred from the substrate to the adjacent spaced material 24.
The argon laser emits in the blue-green region of the visible spectrum, principally at 0.4880 μm. The CO 2 laser emits primarily at 10.6 μm. The Nd:YAG laser emits principally at 1.06 μm. The entire visible spectrum extends from 0.4 μm to 0.7 μm.
It is necessary that the dye or pigment which is used for the recording material be capable of absorbing sufficient energy from the energy source which is used, to vaporize instantaneously without being decomposed. Not all dyes or pigments that are capable of absorbing radiant energy of a particular wavelength make suitable transfer recording materials. To serve as a suitable recording material, the dye or pigment must also have proper thermal characteristics. That is, the recording material should have low thermal conductivity, low density and low specific heat. The material should also have a low vaporization temperature, vaporization over a narrow temperature range (i.e. less than 30° C) and small heat of vaporization.
The thickness and density of the colorant coating affect transferability. Poor transfer results if the colorant layer is either too thick or too thin.
A more thorough understanding of the general mechanics of transference will be derived upon reading the following articles, i.e.:
Ready, J. F., "Effects Due to Absorption of Laser Radiation," Journal of Applied Physics, Vol. 36, No. 2, February 1965; and
Ready, J. F., Bernal, E. G., and Sheperd, L. T., "Mechanisms of Laser-Surface Interactions," Honeywell Corporate Research Center, November 1967.
The present invention is related to an improvement in the method of making a recording material which can be used in the transfer recording process which has been described above, and in other recording processes. It has now been found that dyes or pigments capable of absorbing sufficient energy from the beams of one or more types of lasers and other energy sources to vaporize the dye or pigment without decomposition, can be coated on suitable transparent substrate films from solvent solutions or suspensions without any binder being present, and the resulting dye or pigment-coated product can be satisfactorily used in the recording process.
For example, as illustrated in FIG. 2, a transparent substrate 21, which may be a film of polyethylene, may be coated with a layer 22 of a dye such as Rhodamine B Ex. In the recording process, the dye layer 22 is adjacent to a recording substrate 24 which may be paper, for example.
Any one of several conventional solution or colloidal suspension coating methods may be used to coat the dye (or pigment) layer 22 on the film substrate 21. A solution is prepared by dissolving (or dispersing) 0.1 g of dye (or pigment) per 2 ml of solvent and the solution is applied evenly to the film 21 using a spray gun or a wire-wound rod. In the case of pigments, the composition is usually a colloidal suspension rather than a solution. The solvent is then permitted to evaporate. Adhesion of the dye or pigment is improved in the case of a substrate such as polyethylene, if the polyethylene film is treated with a corona discharge or other surface treatments prior to coating.
Certain solvents are more effective with some dyes than with others. For example, anhydrous isopropyl alcohol has been found to be a good solvent for Rhodamine B Ex. Methyl ethyl ketone is a good dispersant for 1,5-diaminoanthraquinone and 1,2-diaminoanthraquinone.
Some solvents are effective with many different dyes and pigments. In the following Table, the same solvent, TR-590 (a standard denatured alcohol made up of 5 parts by vol. wood alcohol spirits and 100 parts by vol. 190 proof ethanol, each 100 parts by vol. of the mixture also containing 1 part by vol. methyl isobutyl ketone, 1 part 85-88% ethyl acetate, 1 part gasoline) was used in all cases, and the proportion of dye (or pigment) to solvent was 0.1 g of dye (or pigment) per 2 ml of solvent. All of the dyes (or pigments) were coated on the substrates using a wire wound rod to spread the coating composition. After the coating had dried, toughness of the coating was tested by rubbing to an extent believed to be equivalent to what the coated substrate would be subjected to in ordinary handling in a commercial process.
In the following Table, all of the polypropylene and polyethylene samples were corona treated; the remaining samples were not treated.
Table__________________________________________________________________________Dye or Color Index Substrate CoatingPigment Designation Film Toughness__________________________________________________________________________* Pigment(1a) Brilliant Blue 2GLN Solvent Polypropylene AT-36 Fair(Ciba-Geigy) Blue No. 48 (Amoco) corona treated(1b) " " Polyethylene Fair (Package House) corona treated(1c) " " PVC (Polyvinyl Good Chloride)(1d) " " Polycarbonate Good (Lexan) (GE)(2a) Yellow 2GL Solvent Polypropylene Excellent(Ciba-Geigy) Yellow No. 91(2b) " " Polyethylene Excellent(2c) " " PVC Excellent(2d) " " Polycarbonate Excellent(3a) Orange GNG Solvent Polypropylene Excellent(Ciba-Geigy) Orange No. 27(3b) Orange GNG Solvent Polyethylene Excellent(Ciba-Geigy) Orange No. 27(3c) " " PVC Excellent(3d) " " Polycarbonate Excellent(4a) Auramine 0 Conc 130% CI 41000 Polypropylene Good(Allied Chemical)(4b) " " Polyethylene Good(4c) " " PVC Good(4d) " " Polycarbonate Good(5a) Victoria Green WB CI 42000 Polypropylene GoodConc 167%(5b) " " Polyethylene Good(5c) " " PVC Good(5d) " " Polycarbonate Good(6a) Rhodamine B Ex. CI 45170 Polypropylene Excellent(Ciba-Geigy)(6b) " " PVC Excellent(6c) " " Polyethylene Excellent(6d) " " Cellulose acetate 912 Excellent(6e) " " Cellulose triacetate Excellent(7a)*1,5-Diaminoanthraquinone Polyethylene Excellent(Aldrich Chemical Co.)(7b) " Cellulose Acetate Excellent(7c) " Cellulose triacetate Excellent(8a)*1,2-diaminoanthraquinone Polyethylene Excellent(Aldrich Chemical Co.)(8b) " Cellulose acetate 912 Excellent(8c) " Cellulose triacetate Excellent(9) Fluorescein CI 45350 Polyethylene Excellent(10) Sudan I (Aldrich Chemical Co.) CI 12055 Polyethylene Excellent(11)*Black No. 1 " Fair(Shepherd Chemical Co.)(12)*Yellow No. 55 " Fair(Shepherd Chemical Co.)(13)*Blue No. 5 " Fair(Shepherd Chemical Co.)(14)*Green No. 4 " Fair(Shepherd Chemical Co.)(15)*Violet No. 4 " Fair(Shepherd Chemical Co.)(16)*Pure black iron oxide " Fair(Fe.sub.3 O.sub.4 -97%)(Pfizer Chemical Co.)(17)*Carbon black " Fair(E. K. Levy & Sons)__________________________________________________________________________
The recording materials described above can also be used for material transfer other than information recording. For example, they can be used to print decorative patterns on paper or cloth.
The materials can also be used in material transfer methods which use some means of transferring other than a laser beam. A strong focused beam of light can also be used, for example. Impact printing, such as produced on a typewriter, can also be used. Although recording materials for use in impact printing do not have the same requirements with respect to stability at elevated temperatures as materials used in energy beam transfer recording, the present materials are lower in cost than ordinary typewriter ribbon compositions. Moreover, the present materials offer a wider choice of colors than can be found with ordinary typewriter ribbon materials.
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A method of transfer recording comprising selectively irradiating a binderless dry film consisting essentially of a dye or pigment capable of absorbing energy and being vaporized without decomposition.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an automatic fault diagnostic network system and an automatic fault diagnostic method for networks and, more particularly, to an automatic fault diagnostic network system and automatic fault diagnostic method for networks, which automatically diagnose a fault in a network element as a management target at the time of occurrence of the fault.
2. Description of the Prior Art
In general, a network management system for managing a network is connected to it, and the overall structure of the network as a management target and the connection states of network elements are displayed on a built-in display means. A network manager can check through this display means whether, for example, the network is normal or any fault has occurred in any network element.
In recent years, networks have rapidly increased in size and spread over wide areas. When a fault occurs in a network element, it is important to immediately take necessary measures to eliminate this. For this reason, demands have arisen for means by which network managers can properly cope with faults on networks. As such a means, a network management system is constructed from a fault log creation/storage means for automatically detecting a network element in which a fault has occurred, automatically creating a fault log on which at least the name of the network element and the type of fault are recorded, and recording the log, a trouble ticket issuing means for issuing a trouble ticket on which the detailed information recorded on the fault log can be recorded, and a trouble ticket storage means for storing the trouble ticket on which the detailed information is recorded. With such a system, an attempt has been made to improve network management performance at the time of occurrence of a network fault.
The anti-network fault management system disclosed in Japanese Unexamined Patent Publication No. 06-326751 is an example of this system. FIG. 1 is a block diagram showing the function/arrangement of the network management system disclosed in this reference. The arrangement and function of a conventional network management system will be described with reference to FIG. 1. A general network management system includes a display unit 101 for displaying a network as a management target in a diagrammatic form, a control section 102 which is connected to the display unit 101 to control the contents displayed on the display unit 101 or controls an operation unit 104 and database 103 , the operation unit 104 which is connected to the control section 102 to provide it with a signal for designating display contents, and the database 103 which is connected to the control section 102 to store the contents of the network which are to be displayed.
Such a network management system is connected to the network constituted by network elements as management targets through a connection unit. When a fault occurs in one of the network elements, this system displays fault information on the display unit 101 , creates a fault log, and stores it in the database 103 . In the above reference, in particular, there is disclosed an idea that enables a user to quickly find a solution method for a new fault at the time of occurrence of the fault upon referring to a fault log recorded in the past by issuing a trouble ticket on which measures taken against faults by the network manager are also recorded.
According to conventional techniques associated with network management systems, as in the above example, the network management performance can be improved to some extent by issuing or storing a trouble ticket on which a fault log is recorded/updated. With the conventional techniques and methods, however, an improvement in network fault diagnostic function is undesirably limited, and basic problems in network management remain unsolved. The first problem in network management by the conventional network management system is that a network manager must acquire sufficient experience associated with diagnosis because the system has no diagnostic function of acquiring appropriate fault information that enables a search for the cause of the fault, although the system allows the manager to check the occurrence of the fault and its contents to some extent. This problem arises because there is no means that automatically diagnoses a network element in which a fault has occurred.
The second problem in network management is that the network manager must perform determination or operation by himself/herself to check whether a network element in which a fault has occurred can be diagnosed. If, therefore, it is unclear whether each network element has a diagnostic function, or a network maintenance person without any know-how about diagnosis is to perform operation, this problem brings great difficulties in taking countermeasures against network faults.
The third problem in network management is that even if a means for executing diagnosis is prepared because of the necessity of the execution of diagnosis for a search for the cause of a fault, a maintenance person must check a fault in a network element first, and then give the network element an instruction to execute diagnosis from a system other than this network management system. As described above, the conventional network management system has no effective means for taking proper measures against a fault on a network and reducing the work load on a maintenance person.
It is therefore required to automatically find the cause of a fault on the basis of the fault and diagnosis.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an automatic fault diagnostic network system and an automatic fault diagnostic method for networks, which can automatically find the cause of a fault on the basis of fault diagnosis.
It is another object of the present invention to provide an automatic fault diagnostic network system and automatic fault diagnostic method for networks, which can automatically find the cause of a fault on the basis of fault diagnosis by performing autonomous determination on a detected fault instead of making a network manager perform determination and operation to check whether diagnosis of a network element in which the fault has occurred can be made.
In order to achieve the above objects, according to the present invention, there is provided an automatic fault diagnostic network system comprising an automatic diagnostic system and a connection unit for connecting a plurality of network elements to the automatic diagnostic system, wherein the automatic diagnostic system comprises a fault detection unit for detecting an individual fault, and a test unit for running a test to find a cause of the individual fault in the network element in which the individual fault has occurred. This system actively searches for the cause of an individual fault by a test as well as detecting the fault, thereby automating fault processing.
In addition, the system includes a database, and the database stores a plurality of fault data corresponding to a plurality of faults. This allows the test unit to precisely test and determine the cause of the individual fault on the basis of the fault data corresponding to the individual fault detected by the fault detection unit.
The fault data includes the type of network element and fault contents. In many cases, the types of faults that occur in elements are known in advance. The contents of such faults are registered in the database in advance. The contents of a newly detected fault are registered in the database in correspondence with an element every time it is detected.
Information that can specify the contents of a fault is a correspondence between the type of element, e.g., the model or name of the element, and the fault contents. Such a correspondence table is formed in the database. Identical faults occur in elements of the same type. Certain faults occur in only specific types of devices. It is preferable that fault data further include diagnosis execution enable/disable information and diagnosis execution necessity information. With regard to a fault for which no diagnostic test, i.e., test, can be performed, information indicating that diagnosis cannot be executed is preferably prepared. It is also important to have diagnosis necessity information because some fault need not be diagnosed even though it can be diagnosed.
An automatic fault diagnostic method for networks according to the present invention comprises the steps of detecting a fault in a network element, making the fault correspond to fault contents in accordance with the type of element, and confirming the fault contents by testing the fault in accordance with the fault contents. Confirming fault contents is equivalent to finding the cause of a fault. If the cause of a fault is detected, the fault can be recovered by using a conventional means.
As is obvious from the above aspects, the automatic fault diagnostic network system and automatic fault diagnostic method for networks according to the present invention can specify the cause of a fault by executing a test for diagnosis of a network element in which the fault has occurred. If the cause of the fault is specified, the element can be recovered. It can also be determined whether diagnosis can be performed. In addition, even if diagnosis can be performed, it is determined whether diagnosis is necessary. Thereafter, a diagnostic test is executed.
The following effects can be additionally obtained.
(1) When a fault occurs in a network element, processing up to diagnosis can be automatically executed without any manual operation.
(2) Both the fault information and a diagnosis result can be quickly checked. This reduces the amount of work performed by a maintenance person.
(3) Since a diagnosis result can be analyzed by extracting data from the database, appropriate and sophisticated measures can be taken against a fault.
(4) With the above effects, the processing speed and accuracy in network management can be increased regardless of the state of a network and the skill of a maintenance person.
The above and many other objects, features and advantages of the present invention will become manifest to those skilled in the art upon making reference to the following detailed description and accompanying drawings in which preferred embodiments incorporating the principle of the present invention are shown by way of illustrative examples.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing the function/arrangement of a conventional anti-network fault management system;
FIG. 2 is a block diagram showing the schematic arrangement of an automatic fault diagnostic network system according to an embodiment of the present invention;
FIG. 3 is a block diagram showing the details of an automatic diagnostic system in the embodiment shown in FIG. 2;
FIG. 4 is a flow chart showing an example of an automatic fault diagnostic method according to the present invention; and
FIG. 5 is a flow chart showing another example of the automatic fault diagnostic method according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred Embodiments of the present invention will be described below with reference to the accompanying drawings.
In an embodiment of an automatic fault diagnostic network system according to the present invention, an automatic diagnostic system is connected to a network. As shown in FIG. 2, a network element group 3 is connected to an automatic diagnostic system 1 through a connection unit 2 . The network element group 3 includes N network elements 3 - 1 , 3 - 2 , . . . , 3 -N.
FIG. 3 shows the system circuit of the automatic diagnostic system 1 . The automatic diagnostic system 1 is comprised of a fault detection unit 10 , control unit 11 , display unit 12 , test unit 13 , and database 14 . The fault detection unit 10 and test unit 13 are connected to the control unit 11 . The control unit 11 is independently connected to the display unit 12 and database 14 . Fault information 31 of the network element 3 -N in which a fault has occurred is detected by the fault detection unit 10 .
The fault information 31 is sent from the fault detection unit 10 to the control unit 11 . The fault information 31 sent from the fault detection unit 10 is displayed on the display unit 12 by the control unit 11 and stored in the database 14 . The database 14 has diagnosis enable/disable information 32 . The control unit 11 determines, on the basis of the fault information 31 and the diagnosis enable/disable information 32 stored in the database 14 , whether to execute diagnosis of the network element 3 -N. Upon determining that the diagnosis is required and can be executed, the control unit 11 gives an instruction to execute diagnosis to the test unit 13 .
A diagnosis result 33 on the network element 3 -N which is obtained by the test unit 13 after it executes a test in accordance with the diagnosis instruction is sent from the test unit 13 to the control unit 11 . The diagnosis result 33 is displayed on the display unit 12 as information with which the network manager takes measures against the fault, and is also recorded on the database 14 as diagnosis result data 34 corresponding to the fault in the network element 3 -N. The diagnosis result data 34 is held in the database 14 as information that can be made to correspond to an identical fault caused afterward on the network.
FIG. 4 shows an embodiment of an automatic fault diagnostic method for networks according to the present invention. When a fault occurs in any element of the network element group 3 , the fault detection unit 10 detects the fault information 31 (step A 1 ), and sends the fault information 31 to the control unit 11 . The fault information 31 is stored in the database 14 through the control unit 11 (step A 2 ).
Output necessity information indicating whether to output fault information of each network element to the display unit 12 is registered in the database 14 in advance. The control unit 11 reads the output necessity information (step A 3 ) to check whether it is necessary to output the information to the network element 3 -N. If it is necessary to output the information, the fault information 31 is output to the display unit 12 (step A 4 ).
FIG. 5 shows the subsequent steps in the embodiment of the automatic fault diagnostic method for networks. Diagnosis enable/disable information 35 indicating whether diagnosis can be made on a fault in each network element is registered in the database 14 in advance. The control unit 11 reads the diagnosis enable/disable information 35 (step A 5 ), and checks whether diagnosis of the fault in the network element 3 -N can be executed. If it is determined that the diagnosis cannot be performed, the processing is terminated.
Diagnosis necessity information 36 indicating whether an instruction to execute diagnosis is given when a fault occurs in each network element is registered in the database 14 in advance. The control unit 11 reads the diagnosis necessity information 36 (step A 6 ) to check whether diagnosis about the fault in a network element. If it is determined that the diagnosis is unnecessary, the processing is terminated.
If it is determined that diagnosis of the network element can be executed and an instruction to execute diagnosis is given at the time of occurrence of the fault is given, the automatic fault diagnostic network system of the present invention causes the test unit 13 to execute a test on the network element 3 -N (step A 7 ). Upon completion of the test, the control unit 11 receives the diagnosis result 33 associated with the network element 3 -N from the test unit 13 (step A 8 ). The diagnosis result 33 is then sent to the database 14 through the control unit 11 . The diagnosis result can be output/displayed on the display unit 12 (step A 9 ).
As described above, when a fault occurs in the network element 3 -N, operations for detection, diagnosis and test are automatically executed without any manual operation. The maintenance person can check not only the fault information but also the diagnosis result based on the test through the display unit 12 . This reduces the amount of work performed by the maintenance person, and allows the person to quickly take measures against the fault upon analyzing the diagnosis result. Diagnosis of each network element is automatically determined by reading out the diagnosis enable/disable information and diagnosis necessity information registered in the database 14 . Therefore, network managing operation is not influenced by the technical level of the maintenance person.
Although fault information is displayed on the display unit 12 before diagnosis (step A 4 ), an arbitrary display timing can be set for fault information. In this case, both the fault information and the diagnosis result can be displayed after the diagnosis. This makes it possible to shorten the time interval between the instant at which a fault occurs and the instant at which diagnosis of the corresponding network element is started.
In the above embodiment, an inquiry about fault information display or necessity of diagnosis execution is made with respect to the database (step A 3 or A 6 ), and processing for fault information display or diagnosis execution (step A 4 or A 7 ) is executed only if it is determined that fault information display or diagnosis execution is necessary. However, display/non-display operations and diagnosis/non-diagnosis operations can be arbitrarily combined to display all fault information and execute all diagnoses, display no fault information, or execute no diagnosis. This makes it possible to set management conditions corresponding to the maintenance system of each network element or the presence/absence of a maintenance person, thus making operation in network management flexible.
In the above embodiment, the fault detection unit 10 and test unit 13 are discrete units. However, they can be integrated into one interface for network elements. This integration makes it possible to increase the processing speed of the automatic fault diagnostic network system and reduce the apparatus cost.
In the above embodiment, the test unit 13 is used to diagnose a network element in which a fault has occurred. However, this system may have a program having a fault recovery function for each network element as well as a diagnostic function. With this fault recovery program, processing up to fault recovery can be autonomously performed without any manual operation if a target network element is an element in which fault recovery can be performed. This allows fault information and recovery information to be stored in the database 14 .
In the above embodiment, the system makes diagnosis of a network element in which fault information is detected by the fault detection unit 10 . However, a diagnosis target is not limited to a network element, and the network itself is set as a diagnosis target. This allows systematic management of the overall network.
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An automatic fault diagnostic network system includes an automatic diagnostic system and a connection unit for connecting a plurality of network elements to the automatic diagnostic system. The automatic diagnostic system includes a fault detection unit for detecting an individual fault and a test unit for performing a test to find a cause of the individual fault in the network element in which the individual fault has occurred. An automatic network diagnostic method is also disclosed.
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CROSS REFERENCE TO RELATED APPLICATIONS
This application is a division of copending application Ser. No. 561,988 filed Aug. 2, 1990 and now U.S. Pat. No. 5,093,728.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to beam scan velocity modulation (SVM) systems employed for picture sharpness enhancement and more particularly to an output current limiting, apparatus employed in an SVM system.
2. Description of the Related Art
It is well known that an improvement in apparent picture resolution can be achieved by modulating the beam scan velocity in accordance with the derivative of the video signal which controls the beam intensity. This video signal is referred to as the luminance signal and the derivative of the luminance signal is employed for such control. An advantage of this method over a peaking approach to picture sharpness enhancement is the avoidance of blooming of peaked white picture elements.
It is known in the prior art to apply a differentiated video signal to the input of a double ended limiter incorporating a pair of threshold circuits. The limiter consists of two separate differential amplifiers, where each amplifier is separately biased to provide double ended limiting as well as to provide coring. The limiter arrangement develops a doubly clipped signal output which does not respond to excursions of the differentiated signal which lie below selected threshold magnitudes. Thus the gain of the limiter is such as to provide sharpness enhancement for slow transients while precluding excessive supplemental beam deflection with fast transients. The coring capability of the limiter arrangement significantly lessens the likelihood of noise visibility.
It may be desirable, however, to use a single differential amplifier stage, followed by another stage which will provide the coring function. In such an arrangement, it may be easier to design cost effective circuitry that still meets the requirements of a flat group delay response.
As indicated above, in order to provide beam scan velocity modulation, one differentiates the video signal. A differentiator has an increasing output with increasing frequency. Thus, if the input video signal has higher than normal high frequency components, then a linear system would deliver higher than normal output current and dissipate higher than normal power in the output stage. In such a prior art system, it is possible to overdissipate the output stages of the beam scan velocity modulation system by responding to a particular video signals with much high frequency content.
Circuits are known in the prior art which, in addition to providing signal limiting, reduce power dissipation in the output stages. In such circuits, the current flowing in the output power amplifier is detected to provide a control signal used to control the gain of a preamplifier in a preceding stage. This action suppresses the increase of power dissipation in the output power amplifier when a video signal of a certain frequency characteristic is received. No coring of the differentiated signal is provided, and hence there is exhibited inferior operation in the presence of noise. Furthermore, since the feedback reduces the signal gain as a function of output power, overall SVM operation is reduced, tending to produce a less pleasing visual effect.
Still other circuits are known which operate in a different manner to limit power dissipated in the SVM output stages. In these circuits parallel resistor capacitor combinations with long time constants are provided. These RC combinations are in series with emitter electrodes of transistors which are employed in the output power amplifiers of the SVM system. The transistors operate in a Class B mode with the top transistor conducting on one half cycle of its input waveform and with the bottom device conducting on the other half cycle.
Using this scheme, the bias of the base emitter junction becomes a function of the average amount of high frequency detail in the television image and thereby undesirably introduces more or less output stage coring of the signal depending upon the scene information. Furthermore, this approach requires relatively large magnitude, high voltage capacitors which are expensive and bulky.
As an example, the capacitors used may be 47 μf in value and the resistors 20 ohms in value. The voltage requirements on the capacitors may be in excess of 150 volts. Hence, these capacitors are quite large, bulky and expensive.
SUMMARY OF THE INVENTION
In accordance with an inventive arrangement, a first amplifier is responsive to an input video signal and provides peak-to-peak limiting. A driver amplifier receives the limited signal via a buffer amplifier and provides noise coring subsequent to limiting. An output amplifier coupled to the driver amplifier energizes a scan velocity modulation circuit in accordance with the limited and noise cored video signal.
In accordance with another inventive arrangement, a scan velocity modulation circuit includes means for monitoring the current in the output stage of the SVM circuit and controlling the operation of a preceding stage differential amplifier in accordance with the monitored current. Advantageously, this can prevent overdissipation in the output stage.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a color television receiver employing a beam scan velocity modulation system, embodying the invention.
FIG. 2 is a more detailed circuit diagram of the beam scan velocity modulation system of FIG. 1.
FIG. 3(A)-3(D) is a series of waveforms useful in explaining the operation of the circuitry depicted in FIG. 2.
FIG. 4 is a graph useful in explaining operation of the limiting amplifier in FIG. 3.
FIG. 5 is another graph useful in explaining operation of the limiting amplifier.
DETAILED DESCRIPTION
Referring to FIG. 1 there is shown a block diagram of a color television receiver 10, with beam scan velocity modulation. A television antenna 11 is conventionally coupled to a tuner 12. The output of the tuner is applied to an IF stage 13. The baseband composite color output of IF stage 13 is coupled to a video processor 14. Video processor 14 separates the luminance and chrominance components, demodulates the chrominance into color difference signals, and combines the luminance and color difference signals to generate R, G, B output signals. The R, G, B output signals are applied to a kinescope driver circuit 20, which circuit drives the kinescope 21 associated with a conventional color television receiver.
Associated with kinescope 21 is a main deflection yoke 23 comprising respective horizontal and vertical deflection windings, each of which are subjected to energization by respective horizontal and vertical deflection circuits (not illustrated) to develop a raster of scanning lines on the viewing screen of kinescope 21. Supplemental deflection of the respective beams is supplied by an auxiliary deflection coil 26 which operates to provide scan velocity modulation. Coil 26 may be a single coil or a coil having multiple windings.
Energization of SVM coil 26 is provided by a scan velocity modulation circuit, SVM 15, embodying the invention. A luminance video signal Y is generated by video processor 14 and is applied to the input of an amplifier 30 of SVM 15. The output of amplifier 30 is coupled to the input of a differentiator circuit 31 whereby the amplified video signal is differentiated. The video or image representative signal as amplified and differentiated is then applied to the input of a limiting amplifier 32. As will be explained with reference to FIG. 2, limiting amplifier 32 is a single differential amplifier including differentially coupled transistors 51 and 52, and a controllable constant current source 17. The amplifier operates to limit the differentiated video signal both in the positive and negative direction. The output of limiting amplifier 32 is applied to the input of a driver amplifier 33, which includes a coring function. The output of driver 33 is coupled to the input of an output power amplifier stage 34 for converting the applied voltage to an output current. This current is related to the differentiated video signal and is used to drive scan velocity modulation coil 26.
As one may appreciate, the output of the SVM circuitry directly affects the visual image. The circuitry therefore has to have a bandwidth and a group delay characteristic which match that of the video circuitry feeding kinescope 21.
As indicated, differentiator 31 has increasing output with increasing frequency. If the video signal consists of a signal with higher than normal high frequency components, then an SVM circuit will tend to deliver higher than normal output current via output amplifier 34 and therefore the output amplifier would tend to dissipate higher than normal power. It is therefore possible to overdissipate the output stage and damage the output transistors simply by having the circuit respond to a particular video signal.
An advantageous aspect of the invention is an SVM circuit which operates to prevent overdissipation of the output amplifier stage. As shown in FIG. 1, there is a stage 35 which provides current limiting feedback. The circuit to be described in detail develops a control signal from the current monitored in a current sampling resistor 116, which is related to the average current flowing through output amplifier stage 34. The control signal is applied to a controllable current source associated with the differential amplifier portion of limiting amplifier 32. In this manner, when the differentiated input video signal has much signal content, the control voltage operates to reduce the peak-to-peak signal output from the limiting amplifier by affecting the amount of emitter current that flows through the limiting amplifier. In this way, the limiting levels in the limiting amplifier are controlled by the current through the current source. This operation is a closed loop operation and serves to limit the maximum average current allowed to flow in the output devices incorporated in output stage 34.
As an advantageous configuration, the limiting amplifier is a differential amplifier including a variable constant current source such as a transistor, where the base electrode of the transistor receives the control signal to control the current according to the average current flowing in the output stage. The limiting amplifier limits the differentiated video signal for both positive and negative excursions above given thresholds. When the current in the output amplifier stage exceeds a given value, the current source as controlled by the current feedback reduces the peak-to-peak output of the differential limiting amplifier.
In order to achieve optimum operation, coring advantageously is then performed in a separate stage after the limiting amplifier stage and before the output amplifier stage. Hence coring is unaffected by the closed loop operation as described.
Referring to FIG. 2 there is shown a detailed circuit schematic of scan velocity modulation circuit 15, embodying inventive aspects. In addition to employing reference alphanumerics in FIG. 2, component values are also given.
In FIG. 2, luminance video signal Y of FIG. 1 is coupled to a video input terminal 39 of SVM 15. An illustrative input luminance video signal Y is shown in FIG. 3A. This signal is a video signal manifesting a sine-squared pulse and bar input signal.
Video signal Y is applied to input amplifier stage 30 via a resistor 41. Resistor 41 is coupled to the emitter electrode of a transistor 42 arranged in a common base configuration. Biasing for the common base transistor is obtained by a voltage divider consisting of resistors 43 and 44 in series between a source of operating potential +VA and ground.
A bypass capacitor 45 is coupled to the base electrode of transistor 42. Operating potential +VA is obtained from a source of +12 V DC voltage, +VB, and is filtered from the effects of other loads coupled to the +VB source by a resistor 51 and a capacitor 70.
The collector electrode of transistor 42 is directed through a load resistor 46 to the source of operating potential +VA. The collector electrode of transistor 42 is also coupled directly to the base electrode of a transistor 48 arranged in an emitter follower configuration. The collector electrode of transistor 48 is coupled to the source of operating potential +VA. The emitter electrode of transistor 48 is directed to ground through a resistor 49. The emitter electrode is further coupled via a capacitor 50 to the base electrode of a transistor 51. Transistor 51 and a transistor 52 comprise differential limiting amplifier 32, according to an aspect of the invention.
A differentiator 31 comprising a capacitor 55 and a resistor 53 is coupled to the output emitter of emitter follower transistor 48 and to the base of transistor 51. Resistor 53 has one terminal coupled to a terminal of a tank circuit 38 and another terminal coupled to the junction between resistors 71 and 72 of a voltage divider comprising resistors 71, 72 and 73, which, as will be explained, serves to bias the differential limiting amplifier.
Tank circuit 38 comprises an inductor 54 in shunt with capacitor 55. The tank circuit operates to provide a flattened group delay in regard to the differentiator operation in order to provide compensation for the high frequency response of the differentiator. Tank circuit, thus, improves the linearization of the differentiator output with regard to high frequency operation. The base electrode of transistor 51 receives the differentiated video signal VDF at a differential amplifier input terminal 37, the differentiated signal being shown in FIG. 3(B).
The emitter electrode of transistor 51 is coupled via a gain degenerating resistor 62 to the collector electrode of a transistor 65. Transistor 65 is part of a controllable current source 17 that includes transistor 65 in series with a resistor 66.
In a similar manner, transistor 52 has its emitter electrode coupled to the collector electrode of current source transistor 65 via a gain degenerating resistor 63. Resistor 62 and 63 are equal in magnitude. The collector electrode of transistor 52 is coupled to the point of operating potential +VA via a collector load resistor 68. The collector electrode of transistor 52 comprises an output terminal 16 of limiting amplifier 32. The limited SVM signal VLIM at terminal 16 is illustrated in FIG. 3(C).
DC biasing for the differential amplifier is obtained via resistors 71, 72 and 73 forming a voltage divider between the source of operating potential +VA and ground. The base electrode of transistor 52 is coupled to the junction of resistors 71 and 72 via a resistor 60. The base electrode of transistor 52 is coupled to ground via a capacitor 61 which operates as a bypass for high frequency signal components. DC biasing for transistor 51 is obtained by connecting one terminal of resistor 53 to the junction between resistors 71 and 72 and the other terminal to shunt tank circuit 38, with inductor 54 acting as a DC short-circuit. Resistor 60 and resistor 53 are relatively of the same magnitude to assure that transistors 51 and 52 are equally biased at their bases.
The current through the differential amplifier is determined by variable current source 17. The base electrode of transistor 65 of current source 17 is directed to the junction between resistors 72 and 73 of the voltage divider and, as will be explained, is also connected to the collector electrode of a control transistor 118 via a resistor 119 for controlling the current in the limiting stage. This control transistor affects the peak-to-peak output signal of the limiting stage, as will be further explained.
Differential limiter 32 provides double ended limiting. FIG. 3C depicts the output at the collector electrode of transistor 52, and as seen, is a waveform having a limited peak-to-peak value. The clipping level in the differential pair comprising transistors 51 and 52 is a function of the current in current source 17. The dashed line indication in FIG. 3(C), as will be explained, is the control afforded by controllable current source 17.
The collector electrode of transistor 52 is directly connected to the base electrode of an emitter follower transistor 80. The collector electrode of transistor 80 is coupled to a source of operation potential +VB. Operating potential +VB is filtered by a resistor 86 and a capacitor 83. The output emitter electrode of transistor 80 is coupled to a driver stage 33 which provides noise coring, as will be further explained. Advantageously emitter follower transistor 80 serves as a buffer amplifier between the limiter stage 32 and the driver stage 33.
Driver stage 33 comprises an NPN transistor 85 and a complementary type PNP transistor 88, with the base of transistor 85 being directly coupled to the emitter of transistor the base of transistor 88 being coupled to the emitter of transistor 80 via a diode 81. Diode 81 is directly coupled between the bases of the two driver transistors. A resistor 87 is coupled between the emitters of transistors 85 and 88, and a resistor 82 is coupled between the base of transistor 88 and ground.
Transistors 85 and 88 form a Class B amplifier which operates to drive output stage 34. The Class B amplifier also provides a low level noise coring function.
The emitter electrodes of transistors 85 and 88 in Class B driver stage 33 are AC coupled to the respective base electrodes of complementary type transistors 111 and 113 in output stage 34. The emitter electrodes of transistors 85 and 88 are AC coupled through respective resistors 89 and 90 in series with respective capacitors 91 and 92. The emitter electrode of transistor 111 is directed through a resistor 110 to a source of operating potential +VC via a resistor 122. A DC supply filter capacitor 121 is coupled to the junction of resistors 122 and 100. The source of potential +VC is a DC source of relatively high magnitude as, for example, 135 volts, as compared to the source of potential +VB, which is about 14 volts. This enables output amplifier stage 34 to drive high frequency current through SVM coil 26.
The collector electrode of transistor 111 is coupled to one terminal of scan velocity modulation coil 26. The collector electrode of transistor 111 is also coupled to the collector electrode of transistor 113, thereby forming a Class B output stage having an output terminal 18 at the junction of the collector electrodes. The emitter electrode of transistor 113 is coupled via a resistor 114 and a current monitoring or sampling resistor 116 to ground. Resistor 116 is shunted by means of a filter capacitor 115. The average current through output stage 34, including transistors 111 and 113, flows through resistor 116.
Biasing for the output stage is obtained from a voltage divider comprising of resistors 100, 101, 102, and 103, with the base electrode of transistor 111 coupled to the junction of resistors 100 and 101, and with the base electrode of transistor 113 coupled to the junction of resistors 102 and 103.
One end of SVM coil 26 is coupled to output terminal 18, and the other end is coupled to a grounded capacitor 105. In this manner, the SVM coil is AC coupled to the output amplifier, and no DC current flows in the coil. A damping resistor 109 is coupled across SVM coil 26. DC stabilization is provided by coupling the junction of SVM coil 26 and capacitor 105 to the junction of resistors 101 and 102.
Advantageously, noise coring is provided subsequent to differential amplifier limiting stage 32, in both driver stage 33 and amplifier output stage 34.
Consider first the coring operation provided by driver stage 33. DC blocking capacitors 91 and 92 prevent the DC voltages established at the base electrodes of output stage transistors 111 and 113 from being passed back to the emitter electrodes of driver stage transistors 85 and 88. Since the signals out of limiter stage 32 are symmetrical in both amplitude and duration, the average value of the DC voltage at the bases and emitters of transistors 85 and 88 are constant during operation. Due to the bias introduced by diode 81, the DC voltage at the base of transistor 88 is one diode drop less than the voltage at the base of transistor 85. Under normal small signal operation, the DC voltage drop across resistor 87 is very small making the voltages of the emitters of transistors 85 and 88 to be approximately equal. Under these conditions, the average value of the base-emitter voltage for transistors 85 and 88 is one half of the diode drop of diode 81. Absent a signal, this is insufficient to cause transistors 85 and 88 to conduct. These transistors will start to conduct only when the peak-to-peak signal at the emitter of transistor 80 exceeds one diode drop, thus providing a coring offset level. As an example, if the peak-to-peak signal swing at the emitter of transistor 80 is 10 volts and the diode voltage and transistor threshold voltages are 0.7 volts then the percent coring for this stage would be (0.7/10) times 100 or 7 percent. In actuality due to the nonlinearity of the voltage versus current characteristics of a junction, the coring is slightly lower.
Now consider the coring operation provided by amplifier output stage 34. With the condition that the voltage drop across resistor 116 is small with respect to +VC (135 volts), the DC bias for the base-emitter junctions of transistors 111 and 113 are determined by the voltage VC and the voltage divider comprising resistors 100, 101, 102 and 103. These values are selected such that with no signal applied, transistors 111 and 113 are off, with a bias value of Vbias. With a signal applied which is symmetrical in amplitude and duration, these transistors will conduct when the peak signal exceeds the junction threshold (approximately 0.6 volts) less Vbias. This action results in the coring of the signal. As an example, if the peak input signal is 5 volts, Vbias=0.4 volts and the base to emitter threshold voltage of the transistors is 0.6 volts, then the percent coring of the signal would be (0.6-0.4)/5 times 100 or 4 percent.
To limit power dissipation in amplifier output stage 34, a current feedback circuit 35 is coupled between the output stage and controllable current source 17 of differential limiter amplifier stage 32. Current feedback circuit 35 includes sampling resistor 116, filter capacitor 115 in parallel with resistor 116 and the inverting feedback transistor 118, having an input base electrode coupled to sampling resistor 116 via a resistor 120 and having an output collector electrode coupled via resistor 119 to the base of transistor 65, at the junction of voltage dividing resistors 72 and 73. A bypass capacitor 117 is coupled to the base of transistor 118.
The limiter operation of the circuit of FIG. 2 is generally as follows. The clipping levels in limiting amplifier 32 are controlled by the current through controllable current source 17. The current in controllable current source 17 is controlled by the base voltage of transistor 65, which, in turn, by operation of feedback circuit 35, is dependent on the average power or current in output stage 34. The DC path for current from the +VC supply is through transistors 111, 113, and sampling resistor 116. The filtered voltage across resistor 116 is thus a measure of the average current through the output devices. Capacitor 115 in conjunction with resistor 116 provides a filtering time constant of several hundred horizontal line periods, and feedback circuit 35 is relatively unresponsive to current variations at the horizontal rate. Bypass capacitor 117, by being directly coupled to the base electrode of transistor 118, provides further assurance that feedback circuit 35 remains unresponsive to high frequency signals and noise.
The value of resistor 116 is selected such that when the input video signal has substantial high frequency content, the resulting voltage across resistor 116 causes transistor 118 to conduct. When transistor 118 conducts, base current is shunted away from transistor 65, reducing its conduction. The magnitude of current source 17 is reduced, thereby reducing the peak-to-peak signal output from limiting amplifier 32. This is shown in FIG. 3(C) by comparing the solid-line limited waveform without variable limiting to the dashed line waveform with variable limiting.
The clipping levels in the limiting amplifier are controlled by the current I1 in transistor 65, which in turn is controlled by the base voltage of transistor 65.
FIG. 4 shows the limiting conditions for a current I1 of 10 milliamperes, designated as Case 1 and 5 milliamperes, designated as Case 2. In Case 1, a current I1 of 10 milliamperes represents a situation of relatively little high frequency video content and thus relatively low average current through output stage 34 of FIG. 2. In this situation, transistor 118 is cut off and current source transistor 65 is most conductive. In Case 2, a current I1 of 5 milliamperes represents a situation of relatively much high frequency video content and thus relatively high average current through output stage 34. In this situation, transistor 118 is most conductive and current source transistor 65 is least conductive.
As one can see from FIG. 4, VLIM, when limiting in the positive direction, in both cases equals 12 volts, which is the output voltage level when transistor 52 is non-conducting and resistor 68 is pulled up to the +VA supply rail. This occurs in Case 2 for a differentiated input signal VDF of +0.25 volts above its DC level and in Case 1 for an input signal of +0.5 volts. When limiting in the negative direction, when transistor 52 is most conductive, then in Case 1, an output voltage VLIM of +2 volts is provided for an input signal of -0.5 volts, and in Case 2, an output voltage of +7.0 volts is provided for an input signal of -0.25 volts.
Thus, there is a change in the peak-to-peak clipping levels depending upon the current I1 flowing in current source transistor 65. In Case 1 for an input signal VDF having a peak-to-peak value of 1 volt or more, the differential amplifier will produce an output signal having a peak-to-peak value limited to 10 volts. In Case 2 for an input signal VDF having a peak-to-peak value of 0.5 volts or more, the amplifier will produce an output peak-to-peak value limited to 5 volts.
Limiting amplifier stage 32 is DC coupled, via emitter-follower transistor 80 to the Class B operating transistors 85 and 88 of driver stage 33. The output of driver stage 33 is then, however, AC coupled to the output stage 34. Hence FIG. 5 illustrates the two cases of FIG. 4 based on AC coupling to the output driver stages. In other words, FIG. 5 shows the effect of removing the DC component from the voltage VLIM. Thus as one can ascertain from FIG. 4 and FIG. 5, the peak-to-peak or AC clipped level is solely a function of the amount of current flowing in controllable constant current source 17 as controlled by output current feedback circuit 35.
Using the differential limiting amplifier stage 32 embodying an aspect of the invention, variable and AC symmetrical limiting is achieved. The peak-to-peak differentiated output signal is reduced under high average currents. At the same time, the amplitude of the peak-to-peak differentiated input signal VDF necessary to reach the limiting point is also reduced.
As a further advantage, the small signal gain of differential limiting amplifier stage 32 is relatively unchanged by the variable limiting introduced by feedback circuit 35 of FIG. 2. Thus, as idealized in the illustration of FIG. 5, prior to their respective limiting points, the output versus input curves for Cases 1 and 2 have the same slope. This enables the coring action performed in the succeeding driver stage 33 on short duration, low amplitude input signals to remain unaffected by the feedback operation during high average output stage current levels.
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In beam scan velocity modulation (SVM) system for a television receiver, a video signal is applied to a differentiator followed by a limiting differential amplifier. A driver amplifier coupled to the limiting amplifier drives an output stage that supplies current to an SVM coil. Certain video signals with large high frequency content may tend to produce excessive dissipation in the devices of the output stage. To prevent this, a current source for the differential amplifier is controlled by a voltage which is a measure of the average current through the output stage. The magnitude of the current source is varied to thereby vary the peak-to-peak signal output from the limiting amplifier to prevent overdissipation of the output devices. The presence of random noise in the video signal can produce unwanted SVM operation which can impair the viewed image. The unwanted noise component in the video signal can be reduced in amplitude by coring. The coring is unaffected by the variable limiting.
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BACKGROUND OF THE INVENTION
A. Field of Invention
This invention pertains to the art of methods and apparatuses regarding the manufacture and assembly of tires, and more particularly to methods and apparatuses regarding the manufacture of pneumatic tires requiring increased lower sidewall durability.
B. Description of the Related Art
It is known that certain pneumatic tires, such as those suitable for use on an aircraft, are subjected to operating conditions which include relatively high internal pressures, relatively high speeds (often in excess of 300 kilometers per hour), and relatively high deflections. During the taxiing and taking off of an aircraft, the tire deflection may be more than 30%, and on landing may be 45% or more under impact conditions. Such relatively extreme pressures, loads, and deflections put the lower sidewall area of the tire adjacent the beads under severe tests. The high inflation pressures cause large tensile forces in this bead area while the high deflection rates cause high compressive forces in the axially outer portion of the bead area. These extreme operating conditions can tend to decrease the durable life of the lower sidewall and bead areas. As used herein, an “aircraft tire” or a “pneumatic tire suitable for use on an aircraft” is understood to mean a tire of a size and strength specified for use on an aircraft in either the Yearbook of the Tire and Rim Association, Inc., or the Yearbook of the European Tyre and Rim Technical Organization published in the year that the tire is manufactured.
Commonly, the number of plies (carcass plies) placed in the lower sidewall area of a pneumatic tire requiring increased lower sidewall durability, such as an aircraft tire, have been increased and additional reinforcement plies have been added in the bead area in order to increase rigidity and to decrease deformation of the pneumatic tire under load. Typically, both the carcass plies and the reinforcement plies are comprised of the same tire cord fabric. The tire cord fabric may consist of a pair of (ply) cords extending diagonally across the pneumatic tire. These ply cords may extend from a first bead structure to a second bead structure at about a 80°-90° angle with respect to the equatorial plane of the aircraft tire. Each individual ply cord of a particular ply may be at the same angle, but run in the opposite direction, with respect to the other individual ply cord.
Recently, it has become known to use a relatively high modulus tire cord fabric, such as aramid, in constructing both the carcass and reinforcement plies. The high modulus cords may be embedded in an elastomeric material and there may be a plurality of cord ends per inch of elastomeric material. The modulus of a material may generally be defined as the ratio of stress to strain within the linear elastic range of such material. The strain can be defined as the change in length of the material, as a result of the stress, divided by the original length of the material. As applied to tire fabric cord or cable, the cord modulus is the ratio of its longitudinal stress to the resulting strain within the elastic limit of the cord material. A ply of parallel cords also has a corresponding modulus. The ply modulus is equal to the cord modulus multiplied by the cord end count, which may be defined as the number of cord ends per inch, in the ply. Plies made of higher modulus cords (high modulus plies) are currently favored over plies made of lower modulus cords (low modulus plies). High modulus plies are of relatively lower weight and melt at a higher temperature than low modulus plies. The higher melting temperature results in the plies being more resistant to flat-spotting. A method of tire design using high modulus plies is provided in U.S. Pat. No. 6,427,741 titled AIRCRAFT TIRE, which is hereby incorporated by reference.
Although many known pneumatic tires requiring increased lower sidewall durability, such as an aircraft tire, work well for their intended purpose, they do have disadvantages. One disadvantage to using high modulus plies in the construction of aircraft tires is their lower fatigue compression durability as compared to low modulus plies. Lower fatigue compression durability of the plies may cause a premature removal of an aircraft tire from an aircraft liner. This premature removal results in a higher operating cost to the airlines and, may offset and reduced costs to the airlines resulting from the decreased weight of the high modulus plies.
What is needed then is a pneumatic tire with a higher fatigue compression durability without a significant increase in the overall weight of the tire. In providing this higher fatigue compression durability, it is desirable that the tire's footprint is not significantly reduced. Further, it is desirable to localize the compression loading of the pneumatic tire.
SUMMARY OF THE INVENTION
According to one embodiment of this invention, a pneumatic tire has a sidewall structure portion, a tread structure portion, a belt structure portion, and a carcass structure portion. The carcass structure portion has a bead core, an apex, and a carcass reinforcement portion. The carcass reinforcement portion has a first, a second, a third and a fourth high modulus up ply; a first and a second high modulus down ply; and, a first and a second low modulus chipper. The second low modulus chipper is axially outward from the second high modulus down ply and the first low modulus chipper is axially inward from the second high modulus down ply and axially outward from the first high modulus down ply. In another embodiment of the invention, the pneumatic tire comprises an aircraft tire.
According to another embodiment of this invention, a pneumatic tire has a sidewall structure portion, a tread structure portion, a belt structure portion, and a carcass structure portion. The carcass structure portion has a bead core, an apex, and a carcass reinforcement portion. The carcass reinforcement portion has a first, a second, a third and a fourth high modulus up ply; a first and a second high modulus down ply; and, a first and a second low modulus chipper. The second low modulus chipper is axially outward from the second high modulus down ply and the first low modulus chipper is axially inward from the second high modulus down ply and axially outward from the first high modulus down ply. The first high modulus up ply has a first turn-up portion, the second high modulus up ply has a second turn-up portion, the third high modulus Up ply has a third turn-up portion, and the fourth high modulus up ply has a fourth turn-up portion. The distance the first turn-up portion extends radially outward from the center of the bead core is about ⅓ of the diameter of the bead core. The distance the second turn-up portion extends radially outward from the center of the bead core is greater than ½ of the diameter of the bead core and less than the distance the third turn-up portion extends radially outward from the center of the bead core. The distance the third turn-up portion extends radially outward from the center of the bead core is greater than ½ of the diameter of the bead core and less than ½ of the radial height of the apex. The distance the fourth turn-up portion extends radially outward from the center of the bead core is about ¼ of the diameter of the bead core. The distance the first low modulus chipper extends radially outward from the center of the bead core is about ½ of the section height of the pneumatic tire. The distance the second low modulus chipper extends radially outward from the center of the bead core is greater than the radial height of the apex plus 1.5 inches and less than the distance the first low modulus chipper extends radially outward from the center of the bead core. The end of the second high modulus down ply is located a distance radially outward from the center of the bead core that is greater than the radial height of the apex plus about 1.0 inches. The end of the first high modulus down ply is located radially outward from the end of the second high modulus down ply. The first low modulus chipper may extend at least 0.5 inches radially outward from the end of the first high modulus down ply. The second low modulus chipper may extend at least 0.5 inches radially outward from the end of the second high modulus down ply. The radial distance between the end of the second low modulus chipper and the end of the first high modulus down ply may be at least 0.25 inches.
According to another embodiment of this invention, a pneumatic tire may have a sidewall structure portion, a tread structure portion, and a carcass structure portion. The carcass structure portion may have a first high modulus up ply, a first high modulus down ply, and a first low modulus chipper.
According to another embodiment of this invention, a pneumatic tire may have a sidewall structure portion, a tread structure portion, and a carcass structure portion. The carcass structure portion may have a first high modulus up ply, a first high modulus down ply, a second high modulus down ply, and a first low modulus chipper. The first low modulus chipper is axially outward from the first high modulus down ply and axially inward from the second high modulus down ply.
According to another embodiment of this invention, a pneumatic tire may have a sidewall structure portion, a tread structure portion, and a carcass structure portion. The carcass structure portion may have a first high modulus up ply, a first high modulus down ply, a first low modulus chipper, and a second low modulus chipper. The second low modulus chipper is axially outward from the second high modulus down ply.
According to another embodiment of this invention, a pneumatic tire may be an aircraft tire having a sidewall structure portion, a tread structure portion, and a carcass structure portion. The carcass structure portion may have a first high modulus up ply, a first high modulus down ply, and a first low modulus chipper. The first high modulus up ply and the first high modulus down ply comprise an aramid and the first low modulus chipper comprises a nylon.
According to another embodiment of this invention, a pneumatic tire may be an aircraft tire having a sidewall structure portion, a tread structure portion, and a carcass structure portion. The carcass structure portion may have at least a first high modulus up ply, at least a first high modulus down ply, and a first low modulus chipper. The high modulus up plies and the high modulus down plies comprise an aramid and the first low modulus chipper comprises a nylon.
According to another embodiment of this invention, a pneumatic tire may be an aircraft tire having a sidewall structure portion, a tread structure portion, and a carcass structure portion. The carcass structure portion may have at least a first high modulus Up ply, at least a first high modulus down ply, a first low modulus chipper, and a second low modulus chipper. The at least a first high modulus up plies and the at least a first high modulus down plies comprise an aramid and the first and the second low modulus chippers comprise a nylon. The first low modulus chipper is axially outward from all of the high modulus down plies and the second low modulus chipper is axially inward from at least one of the first high modulus down plies.
According to one embodiment of this invention, a method of constructing a pneumatic tire includes applying an inner liner, applying a carcass structure, applying a belt package, and applying a tread structure. The carcass structure has a carcass reinforcement portion that has a first high modulus up ply, a first high modulus down ply, and a first low modulus chipper.
According to another embodiment of this invention, a method of constructing a pneumatic tire includes applying an inner liner, applying a carcass structure, applying a belt package, and applying a tread structure. The carcass structure has a carcass reinforcement portion that has a first high modulus up ply, a first high modulus down ply, a second high modulus down ply, a first low modulus chipper, and a second low modulus chipper. The second low modulus chipper is axially outward from the second high modulus down ply and the first low modulus chipper is axially inward from the second high modulus down ply and axially outward from the first high modulus down ply.
According to another embodiment of this invention, a method of constructing a pneumatic tire includes applying an inner liner, applying a carcass structure, applying a belt package, and applying a tread structure. The carcass structure has a carcass reinforcement portion that has a first high modulus up ply, a first high modulus down ply, a second high modulus down ply a first low modulus chipper, and a second low modulus chipper. The second low modulus chipper is axially outward from the second high modulus down ply and extends at least 0.5 inches radially outward from the end of the second high modulus down ply. The first low modulus chipper is axially inward from the second high modulus down ply and axially outward from the first high modulus down ply and extends at least 0.5 inches radially outward from the end of the first high modulus down ply.
According to another embodiment of this invention, a method of constructing a pneumatic tire includes applying an inner liner, applying a carcass structure, applying a belt package, and applying a tread structure. The carcass structure has a carcass reinforcement portion that has a first high modulus Up ply, a first high modulus down ply, a second high modulus down ply a first low modulus chipper, and a second low modulus chipper. The second low modulus chipper is axially outward from the second high modulus down ply and extends at least 0.5 inches radially outward from the end of the second high modulus down ply. The first low modulus chipper is axially inward from the second high modulus down ply and axially outward from the first high modulus down ply and extends at least 0.5 inches radially outward from the end of the first high modulus down ply. The radial distance between the end of the second low modulus chipper and the end of the first high modulus down ply is at least 0.25 inches.
One advantage of this invention is that the pneumatic tire has a higher fatigue compression durability than that of a pneumatic tire comprised entirely of high modulus plies without a significant increase in the overall weight of the vehicle tire. The invention may instead result in a weight savings of as much as 15% over the conventional low modulus pneumatic tire. For example, the inventor has discovered that the inventive tire could yield a decrease in tire weight of about 50 pounds as compared to a tire (1400×530R23 40 pr 235 mph, 300 lbs) comprised of all low modulus materials. By ensuring that the weight of an inventive pneumatic tire suitable for use on an aircraft is not significantly increased, any savings resulting from the aircraft tire's higher fatigue compression durability is not negated by other factors, for example, higher fuel expenditures, resulting from the increased weight of the aircraft tire. Further, any additional increase in the weight of the aircraft tire is contrary to the aircraft tire design parameter for minimizing the weight of the airliner.
Another advantage of this invention is that the invention's higher fatigue compression durability significantly reduces the occurrence of premature removal of an aircraft tire from an aircraft. A higher fatigue compression durability increases the number flexes an aircraft tire may endure prior to a significant increase in the risk of tire failure resulting from the compression forces occurring during taxiing, take-off, and landing.
Still other benefits and advantages of the invention will become apparent to those skilled in the art to which it pertains upon a reading and understanding of the following detailed specification.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention may take physical form in certain parts and arrangement of parts, embodiments of which will be described in detail in this specification and illustrated in the accompanying drawings which form a part hereof and wherein:
FIG. 1 is a cross-sectional view of a pneumatic tire taken in an axial plane showing one embodiment of this invention.
FIG. 2 is an enlarged cross-sectional view of a part of the crown and upper sidewall region of the pneumatic tire shown in FIG. 1 .
FIG. 3 is an enlarged cross-sectional view of a part of the lower sidewall and bead region of the pneumatic tire shown in FIG. 1 .
FIG. 4 is a diagrammatical view of the part of the lower sidewall and bead region of the pneumatic tire shown in FIG. 3 .
FIG. 5 is a block diagram of a method of building an pneumatic tire in accordance with one embodiment of the invention.
DEFINITIONS
The following terms may be used throughout the descriptions presented herein and should generally be given the following meaning unless contradicted or elaborated upon by other descriptions set forth herein.
“Aircraft Tire” means a tire of a size and strength specified for use on an aircraft in either the Yearbook of the Tire and Rim Association, Inc., or the Yearbook of the European Tyre and Rim Technical Organization published in the year that the tire is manufactured. Generally, an aircraft tire has a laminated mechanical device of generally toroidal shape, usually an open-torus having beads and a tread and made of rubber, chemicals, fabric, and perhaps steel or other materials.
“Apex” means a wedge of elastomeric material placed beside (radially above the bead or bead core) the bead (or bead core) that supports the bead-area and minimizes flexing in the bead-area.
“Axial” and “axially” means lines or directions that are parallel to the axis of rotation of the tire.
“Bead” or “bead core” means that part of the tire comprising an annular tensile member wrapped by ply cords and shaped, with or without other reinforcement elements such as flippers, chippers, apexes or fillers, toe guards and chafers to fit the design rim.
“Belt” means at least two layers of plies of parallel cords, woven or unwoven, underlying the tread, unanchored to the bead, and having both left and right cord angles in the range from 17° to 33° with respect to the equatorial plane of the tire.
“Carcass” means the tire structure apart from the belt structure, tread, undertread, and sidewall rubber over the plies, but including the beads.
“Chafers” refers to narrow strips of material placed around the outside of the bead to protect cord plies from the rim, distribute flexing above the rim, and to seal the tire.
“Chipper” means a reinforcement structure located in the bead portion of the tire.
“Circumferential” means circular lines or directions extending along the surface of the sidewall perpendicular to the axial direction.
“Cord” means one of the reinforcement strands of which the plies in the tire are comprised.
“Crown” refers to substantially the outer circumference of a tire where the tread is disposed.
“Equatorial Plane (EP)” means the plane perpendicular to the tire's axis of rotation and passing through the center of its tread.
“Flipper” means an additional reinforcement (usually fabric) that is placed around the bead/apex and, usually, between the bead/apex and the carcass ply.
“Footprint” means the contact patch or area of contact of the tire tread with a flat surface at zero speed and under normal load and pressure.
“Inner” means toward the inside of the tire.
“Modulus” or “stress-strain ratio” means the modulus of elasticity of a material or the rate of change of strain as a function of stress. For purposes of this patent, a low or lower modulus material refers to a material with a modulus of elasticity less than 19 Giga Pascal (GPa) and high or higher modulus material refers to any material having a modulus of elasticity greater than 19 GPa.
“Nominal Rim Diameter” means the average diameter of the rim flange at the location where the bead portion of the tire seats.
“Outer” means toward the tire's exterior.
“Ply” means a continuous layer of rubber-coated parallel cords.
“Radial” and “radially” mean directions radially toward or away from the axis of rotation of the tire.
“Section Height” means the radial distance from the nominal rim diameter to the outer diameter of the tire at its equatorial plane.
“Shoulder” means the upper portion of sidewall just below the tread edge.
“Sidewall” means that portion of a tire between the tread and the bead area.
“Tenacity” means the stress expressed as force per unit linear density of an unstrained specimen (gm/tex or gm/denier), (usually used in textiles).
“Tread” means a molded rubber component which, when bonded to a tire casing, includes that portion of the tire that comes into contact with the road when the tire is normally inflated and under normal load.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings wherein the showings are for purposes of illustrating embodiments of the invention only and not for purposes of limiting the same, FIG. 1 shows a pneumatic tire suitable for use as an aircraft tire 10 including a carcass structure 50 that may comprise high modulus up and down plies and a low modulus chipper that may be “sandwiched” or in between the high modulus up plies, made in accordance with one embodiment of this invention. While the tire shown is an aircraft tire, it is understood that the invention may be practiced with respect to tires intended for other applications also, such as passenger vehicle tires, light truck or sport utility vehicle tires, truck tires, agricultural tires, tires used on construction equipment, or on any type of tire chosen with sound engineering judgment. The aircraft tire 10 may comprise a tread structure 20 , a belt package 24 , a pair of sidewall structures 40 a , 40 b , and the carcass structure 50 . The tread structure 20 may be located in the crown of the aircraft tire 10 and may extend circumferentially about the aircraft tire 10 . The tread structure 20 may be a molded rubber, ground-engaging component and may provide traction for the aircraft tire 10 .
With reference now to FIGS. 1-2 , the belt package 24 may be arranged between the carcass structure 50 and the tread portion 30 . The belt package 24 may be characterized by a plurality of plies of parallel cords, or belt layers, woven or unwoven, and unanchored to a bead core 62 . In one embodiment, the belt package 24 may comprise, for example, six zigzag belt plies 26 a , 26 b , 26 c , 26 d 26 e , and 26 f and two spiral wound belt layers 28 a , 28 b . The spiral wound belt layers 28 a , 28 b may be positioned radially outward from the zigzag belt layers 26 a - 26 f . The number and type of belt layers comprising the belt package 24 may vary according to the specific tire construction.
With reference now to FIG. 1 , the sidewall structures 40 a , 40 b may extend radially inwardly from the axially outer edges 22 a , 22 b of the tread structure 20 and terminate at their radial extremities in a bead portions 60 a , 60 b of the carcass structure 50 . The sidewall structures 40 a , 40 b may have upper portions 42 a , 42 b and lower portions 44 a , 44 b . The upper portions may be located radially inward of the tread structure 20 and radially outward of a maximum section width MSW of the aircraft tire 10 . The lower portions 44 a , 44 b may be radially inward of the maximum section width MSW and radially outward of the bead portions 60 a , 60 b.
With reference now to FIGS. 1 , 3 - 4 , the carcass structure 50 may be cord-reinforced and may extend circumferentially about the aircraft tire 10 and may extend axially from the bead portion 60 a to the bead portion 60 b . The carcass structure 50 may comprise the bead portions 60 a , 60 b , an inner-liner 52 , and a carcass reinforcement structure 70 . The inner-liner 52 may be radially inward from the carcass reinforcement structure 70 and may surround an air chamber (not shown) formed by the aircraft tire 10 when mounted on a suitable rim (not shown). The inner-liner 52 may be generally air impervious and may extend from bead portion 60 a to bead portion 60 b.
With continued reference to FIGS. 1 , 3 - 4 , the bead portions 60 a , 60 b may each comprise a bead core 62 , and an apex 64 . The bead core 62 may be an annular inextensible structure and may comprise a circular cross section that may extend circumferentially around the aircraft tire 10 . In another embodiment, the bead portions 60 a , 60 b may comprise a plurality of bead cores, for example two (2) or three (3) and may comprise various cross-sectional shapes such as hexagonal or oval. The bead portions 60 a , 60 b may comprise any number of bead cores or any cross-sectional shape chosen with sound engineering judgment. The apex 64 may be located directly adjacent to and radially outward from the bead core 62 . The apex 64 may comprise an elastomeric material and may have substantially the shape of a triangle.
With continued reference to FIGS. 1 , 3 , and 4 , the carcass reinforcement structure 70 may comprise a plurality of carcass plies 72 . The plurality of carcass plies 72 may be comprised of high modulus cords or cables, for example, aramid or steel, or any other high modulus material having similar properties, or a combination of such high modulus materials, chosen with sound engineering judgment. Such high modulus cords may comprise any suitable denier and any suitable twist and may be treated to increase their bond strength to rubber. Additionally, aramid cords may be coated with an adhesive or an adhesive/epoxy combination.
With continued reference to FIGS. 1 , 3 , and 4 , the plurality of carcass plies 72 may comprise up plies (also known as inner plies) and down plies (also known as outer plies). In one embodiment, the carcass reinforcement structure 70 may comprise a first up ply 74 , a second up ply 76 , a third up ply 78 , and a fourth up ply 79 as well as a first down ply 80 , and a second down ply 82 . In another embodiment, the carcass structure 70 comprises one up ply and one down ply. The carcass reinforcement structure 70 may comprise any number of up plies and down plies chosen with sound engineering judgment. The plurality of carcass plies 72 may be positioned such that the first up ply 74 is the axially innermost carcass ply, the second up ply 76 may be positioned axially outward from the first up ply 74 and axially inward from the third up ply 78 , and the fourth tip ply 79 may be positioned axially outward from the third up ply 78 . The down plies may be positioned such that the first down ply 80 is positioned axially outward from the fourth up ply 79 and axially inward from the second down ply 82 . The second down ply 82 may be the axially outermost carcass ply.
With continued reference to FIGS. 1 , 3 , and 4 , the up plies 74 , 76 , 78 , and 79 may extend radially inward along the axially inner side of a bead core 62 . The up plies 74 , 76 , 78 and 79 may bend around the bead core 62 and begin to extend radially outward along the axially outer side of the bead core 62 and may form a first, second, third, and fourth turn-up 74 a , 76 a , 78 a , and 79 a . The first, second, third, and fourth turn-ups 74 a , 76 a , 78 a , and 79 a may extend to any point chosen with sound engineering judgment. In one embodiment of the invention, the first turn-up 74 a may extend to a point radially outward from the reference line XX′. The distance H 1 B that the first turn-up 74 a extends radially outward from the reference line XX′ may be determined to be equal to ⅓ of a bead core diameter A. In another embodiment of the invention, the second turn-up 76 a may extend to a point radially outward from the reference line XX′ (A/3). The distance H 1 C that the second turn-up 76 a extends radially outward from the reference line XX′ may be determined to be greater than ½ of the bead core diameter A but less than a distance HID that the third turn-up 78 a extends radially outward from the reference line XX′ ((A/2)<H 1 C<H 1 D). In another embodiment of the invention, the third turn-up 78 a may extend to a point radially outward from the reference line XX′. The distance HID that the third turn-up 78 a extends radially outward from the reference line XX′ may be determined to be greater than ½ of the bead core diameter A but less than the a distance equal to ½ of an apex height D corresponding to the distance that a radially outermost point AA of the apex 64 extends radially outward from the reference line XX′ ((A/2)<H 1 D<(D/2)). In yet another embodiment of the invention, the fourth turn-up 79 a may extend to a point radially outward from the reference line XX′. The distance H 1 A that the fourth turn-up 79 a extends radially outward from the reference line XX′ may be determined to be equal to ¼ of the bead core diameter A (A/4).
With continued reference to FIGS. 1 , 3 , and 4 , the down plies 80 , 82 may extend radially inward along the axially outer side of the up plies 74 , 76 , 78 and 79 . The down plies 80 , 82 may extend such that the ends of the down plies 80 , 82 are situated radially above the reference line XX′. The down plies 80 , 82 may extend such that their ends are positioned at any point chosen with sound engineering judgment. A first chipper 85 may be axially inward from the first down ply 80 and axially outward from the second down ply 82 thereby separating the first down ply 80 and the second down ply 82 . A second clipper 84 may be axially outward from the first down ply 80 such that the first chipper 85 and the second chipper 84 may be said to “sandwich” the first down ply 80 . The first chipper 85 and the second chipper 84 may be low modulus chippers. In one embodiment of the invention, the Up plies 74 , 76 , 78 , and 79 and the down plies 80 , 82 may be comprised of an aramid and the first chipper 85 and the second chipper 84 may be comprised of a nylon. The ends of the first chipper 85 and the second chipper 84 may be positioned at any location chosen with sound engineering judgment. In one embodiment of the invention, the end of the first chipper 85 may be located a distance H 2 A radially above the reference line XX′. The distance H 2 A may correspond to a value that is less than ½ of the section height SH of the aircraft tire 10 (H 2 A<(SH/2)). In another embodiment of the invention, the end of the second chipper 84 may be located a distance H 2 B radially above the reference line XX′. The distance H 2 B may correspond to a value that is greater than the apex height D plus 1.5 inches but less than the distance H 2 A ((D+1.5″)<H 2 B<H 2 A).
With continued reference to FIGS. 1 , 3 , and 4 , in one embodiment of the invention, the end of the second down ply 82 may be located a distance EP 2 above the reference line XX′. The distance EP 2 may correspond to a value that is greater than the apex height D plus 1.0 inches (EP 2 >(D+1.0″)). In another embodiment of the invention, the end of the first down ply 81 may be located a distance EP 1 above the reference line XX′. The distance EP 1 may correspond to a value that is greater than the distance H 2 A and is also greater than the distance EP 2 (EP 1 >H 2 A, EP 1 >EP 2 ). In one embodiment of the invention, the first down ply 80 may comprise an overlap portion OL 1 in which the first chipper 85 overlaps or covers the first down ply 80 . In another embodiment of the invention, the second down ply 82 may comprise an overlap portion OL 2 in which the second chipper 84 overlaps or covers the second down ply 82 . In one embodiment of the invention, the first and second overlap portions OL 1 , OL 2 may be at least 0.5 inches. The first and second overlap portions OL 1 , OL 2 may comprise any amount of overlap chosen with sound engineering judgment. The end of the second chipper 84 and the end of the first down ply 80 may be separated by a distance G. In one embodiment of the invention, the distance G between the end of the second chipper 84 and the end of the first down ply 80 may be at least 0.25 inches. The end of the second chipper 84 and the end of the first down ply 80 may be separated by any distance chosen with sound engineering judgment.
With reference now to FIGS. 1-5 , a method for manufacture of an aircraft tire according to one embodiment of the invention will generally be described. Two stage tire building utilizing either a first stage tire drum in combination with a second stage tire drum or a single drum that can be moved from a first stage position to a second stage position, is well known. The first stage may comprise the step of building a band for the carcass structure 50 that includes the inner-liner 52 and the carcass reinforcement structure 70 . Band building is well known in the art. One method of band building may comprise the use of a belt or a collapsible drum to which the inner-liner 52 may be applied. The inner-liner 52 may be applied in the form of a continuous sheet followed by the application of the up plies 74 , 76 , 78 and 79 . The up plies 74 , 76 , 78 and 79 may be applied offset from each other with respect to the inner-liner 52 . Following the application of the up plies 74 , 76 , 78 and 79 , the bead cores 62 may be applied followed by the apex 64 . In one embodiment, the up plies 74 , 76 , 78 and 79 may then be turned around the bead cores 62 in order to form their respective turn-ups 74 a , 76 a , 78 a , and 79 a.
With continued reference to FIGS. 1-5 , the up plies 74 , 76 , 78 and 79 , may be mechanically folded over the bead cores 62 and the apex 64 . Next, the first down ply 80 may be applied followed by the application of the first low modulus chipper 85 . The second down ply 82 may then be applied followed by the application of the second low modulus chipper 84 . The first chipper 85 and the second chipper 84 and the first and second down plies 80 , 82 may be positioned offset from each other to allow for their respective ends to extend to their respective points as described above. The low modulus first chipper 85 and the low modulus second chipper 84 may be turned atop of the up plies 74 , 76 , 78 and 79 . In another embodiment of the invention, the second down ply 82 and the second low modulus chipper 84 may be applied prior to the first down ply 80 and the first low modulus chipper 85 . Following the application of the down plies 80 , 82 and the low modulus chippers 84 , 85 , the sidewall structures 40 a , 40 b may be applied. A second stage may include assembling the tread structure 20 together with the belt package 24 and combining them with the carcass structure 50 and the sidewall structures 40 a , 40 b assembled in the first step, utilizing known methods to form the uncured, or green, aircraft tire 10 .
Various embodiments have been described, hereinabove. It will be apparent to those skilled in the art that the above methods and apparatuses may incorporate changes and modifications without departing from the general scope of this invention. It is intended to include all such modifications and alterations in so far as they come within the scope of the appended claims or the equivalents thereof.
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A pneumatic tire may use a combination of high modulus and low modulus plies to provide increased fatigue compression durability without significantly increasing the weight of the tire.
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TECHNICAL FIELD
This invention relates generally to particulate filters, and more particularly, to controlling the regeneration of particulate filters.
BACKGROUND
Particulate filters for engine exhaust are gaining importance as engine manufacturers seek to reduce emissions. Particulate filters are used to filter out particulate matter from the engine's exhaust stream, and to periodically regenerate when the filter reaches a certain degree of clogging. Regeneration of the filter is typically accomplished by increasing the temperature of the particulate filter to a point where the accumulated particulates are burned off, thereby unclogging the filter.
Catalysts of various compositions are frequently used to elevate the temperature of the particulate filter. Catalysts, however, typically only function well when they are above their respective “light off” temperature. The “light off” temperature for a catalyst is typically a temperature above which the catalyst is able to convert unburned hydrocarbons at some predetermined efficiency. Typically at temperatures below the “light off” temperature the catalyst converts a negligible amount of hydrocarbons, while at temperatures above the “light off” temperature, the catalyst may operate at a substantially higher efficiency.
The unburned hydrocarbons may be delivered to the catalyst through a variety of ways, such as, for example, injecting a shot of diesel fuel after substantial combustion within a cylinder has occurred. The diesel fuel then exits the cylinder through the exhaust valve and reaches the catalyst in relatively unchanged form.
Control of the temperatures of the catalyst and particulate filter have been relatively crude, and a better techniques and devices for performing this function are desired.
SUMMARY OF THE INVENTION
The present invention provides apparatuses and methods for regenerating a particulate filter. A first temperature corresponding to a temperature of a catalyst that is thermally coupled with a particulate filter is determined. A second temperature corresponding to the temperature of the particulate filter is determined. Substantially no unburned hydrocarbons are delivered to the catalyst when the first temperature is below a first threshold and unburned hydrocarbons are delivered to the catalyst when the first temperature is above the first threshold and the second temperature is below a second threshold.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view of a cylinder of an engine along with an associated particulate filter and control devices therefore according to one embodiment of the invention.
FIG. 2 is a flow chart according to one embodiment of the invention.
DETAILED DESCRIPTION
FIG. 1 is a side view of a cylinder 10 of an engine 12 along with an associated particulate filter 14 and control devices therefore according to one embodiment of the invention. Although only a single cylinder 10 is shown for purposes of illustration, the invention may be equally applicable to multi-cylinder engines, as well as rotary-engines. The invention may be practiced in both two and four stroke combustion cycles. The engine 12 includes an intake air passageway 16 and at least one intake valve 18 disposed in the intake air passageway and operable to fluidly connect the intake air passageway 16 with the cylinder 10 by ways known to those skilled in the art.
A piston 20 may be disposed within the cylinder 10 and reciprocates, delivering power to a crank shaft 22 during the combustion cycle by ways known to those skilled in the art.
A fuel delivery device, such as a fuel injector 24 may be fluidly coupled with the cylinder 10 to provide a combustible fuel as a function of a control signal (“CONTROL”) by ways known to those skilled in the art. The fuel injector 24 may also serve as a hydrocarbon delivery system as will be described further below. Other types of hydrocarbon delivery systems delivering the same or other sources of hydrocarbons may be used in addition to or instead of fuel injector 24 as will become evident from the below description. Any of a variety of hydrocarbons known to those skilled in the art may be delivered, such as, gasoline, natural gas, kerosene, and crude oil. Furthermore, in other embodiments of the invention, an extra in-exhaust fuel injector (not shown) or other hydrocarbon delivery device could be used to deliver the hydrocarbons in lieu of or in addition to the fuel injector 24 .
At least one exhaust valve 26 may be fluidly coupled with the cylinder 10 and may be operable to couple the cylinder 10 with an exhaust path 28 by ways known to those skilled in the art.
A catalyst 30 may be coupled with the exhaust path 28 to receive exhaust gases from the cylinder 10 . The catalyst 30 is typically selected to convert hydrocarbons (“HC”) to heat by ways known to those skilled in the art. The catalyst 30 may be any of a variety of materials known to those skilled in the art.
The catalyst 30 typically has a “light-off” temperature. The “lightoff” temperature is typically a temperature at which the catalyst converts a desired percentage of hydrocarbons to heat, e.g., a particular efficiency.
A first temperature sensor 32 may be thermally coupled with the catalyst 30 to determine a first temperature (“T1”) indicative of a temperature of the catalyst 30 . The first temperature sensor 32 may be operable to transmit a first temperature signal as a function of the first temperature. As a practical matter, the first temperature sensor 32 may be disposed in the exhaust path 28 in close proximity to the catalyst 30 . Other locations that provide a temperature correlated to the temperature of the catalyst 30 may also be used.
The particulate filter 14 is typically thermally coupled with the catalyst 30 . The particulate filter 14 is operable to filter particulate matter from the exhaust gases emitted from the cylinder 10 by ways known to those skilled in the art.
During filtration, the particulate filter 14 accumulates the particulate matter from the exhaust gas. Over time, the particulate filter 14 may become partially or completely clogged and require regeneration.
Regeneration of the particulate filter 14 may be achieved by elevating the temperature of the particulate filter to a temperature sufficient to burn-off the accumulated particulates. This temperature is typically 450-600 degrees Celsius, although the range may vary.
A second temperature sensor 34 may be thermally coupled with the particulate filter 14 to determine a second temperature indicative of a temperature of the particulate filter. The second temperature sensor 34 may be operable to transmit a second temperature signal as a function of the second temperature. As a practical matter, the second temperature sensor 34 may be disposed in the exhaust path 28 in close proximity to the particulate filter 14 . Other locations that provide a temperature correlated to the temperature of the particulate filter 14 may also be used.
A regeneration controller 36 , such as an electronic engine control module (“ECM”) or fuel injector control module, may be coupled with the first and second temperature sensors to receive the first and second temperature signals. The regeneration controller 36 may be any of a variety of type of ECM's known to those skilled in the art. The controller 36 may be operable to transmit the control signal CONTROL as a function of the first and second temperature signals, as will be further explained below.
The regeneration controller may be further operable to determine, or receive a signal indicative of, when regeneration of the particulate filter 14 is desired. This may be accomplished by any of a variety of ways known to those skilled in the art.
In operation, when regeneration of the particulate filter 14 is desired, the regeneration controller 36 causes the hydrocarbon delivery system to deliver unburned hydrocarbons to the catalyst 30 . In the illustrated example, the regeneration controller 36 transmits an appropriate control signal CONTROL to fuel injector 24 to cause the fuel injector 24 to inject fuel in the form of a second shot, for example, into the cylinder late in the combustion cycle, or after significant or all of the conventional combustion occurs.
When the exhaust valve 24 opens during the exhaust stroke, the fuel, a.k.a unburned hydrocarbons, passes into the exhaust path 28 , and to the catalyst 30 . The unburned hydrocarbons cause the catalyst 30 to heat up, thereby heating the particulate filter 14 to a temperature that burns off at least some of the accumulated particulates, regenerating the particulate filter 14 . The temperature of the particulate filter may be held at this regeneration temperature for as long as desired, typically until the majority of accumulated particulates have been burned off.
In one embodiment of the invention, it may be desirable to only deliver unburned hydrocarbons to the catalyst 30 when the first temperature T 1 is above the “light-off” temperature of the catalyst. This prevents unburned hydrocarbons from passing through the catalyst by virtue of the fact that they are not converted to heat, and out into the atmosphere.
The regeneration controller 36 may also be used for closed loop control of the second temperature T 2 . By determining the second temperature T 2 , the regeneration controller 36 may control the amount of hydrocarbons delivered into the exhaust stream, and thereby to the catalyst. Typically the more hydrocarbons delivered, the hotter the catalyst 30 will get, and the hotter the particulate filter and the second temperature T 2 will get. Similarly, if the second temperature T 2 should become higher than desired, the regeneration controller 36 can reduce the amount of hydrocarbons delivered into the exhaust stream and to the catalyst 30 .
FIG. 2 is a flow chart 50 according to one embodiment of the invention. In block 52 the first temperature T 1 corresponding to the temperature of the catalyst 30 is determined.
In block 54 , the first temperature T 1 is compared with the “lightoff” temperature of the catalyst 30 . If the first temperature T 1 is not greater than or equal to the “light-off” temperature, control passes back to block 52 . If the first temperature T 1 is greater than or equal to the “light-off” temperature, control passes to block 56 .
In block 56 , the second temperature T 2 corresponding to the temperature of the particulate filter 14 is determined.
In block 58 , the second temperature T 2 is controlled via a closed loop control system to a desired temperature, such as the regeneration temperature of the particulate filter. The closed loop system may be any of a variety of closed loop control systems known to those skilled in the art.
INDUSTRIAL APPLICABILITY
Embodiments of the invention may be used to control the regeneration of a particulate filter using a catalyst and unburned hydrocarbons. By monitoring the first temperature T 1 , the regeneration controller 36 can ensure that unburned hydrocarbons are only added to the exhaust stream during conditions allowing the catalyst 30 to convert them to heat. In addition, the regeneration controller 36 can use the second temperature T 2 as feedback to ensure that the proper amount of hydrocarbons are added to the exhaust path to achieve and maintain the particulate filter at a temperature that will cause regeneration.
From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit or scope of the invention. Accordingly, the invention is not limited except as by the appended claims.
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Apparatuses and methods for regenerating a particulate filter. A first temperature corresponding to a temperature of a catalyst that is thermally coupled with a particulate filter is determined. A second temperature corresponding to the temperature of the particulate filter is determined. Substantially no unburned hydrocarbons are delivered to the catalyst when the first temperature is below a first threshold and unburned hydrocarbons are delivered to the catalyst when the first temperature is above the first threshold and the second temperature is below a second threshold.
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CLAIMING BENEFIT OF PRIOR FILED U.S. APPLICATION
This application claims the benefit of U.S. Provisional Application Ser. No. 60/866,890 filed on Nov. 22, 2006. The contents of this document are hereby incorporated by reference herein.
FIELD OF THE INVENTION
The present invention relates to improvements to apparatuses and methods for forming a seal around cables that are passed through an opening of a sealed enclosure.
BACKGROUND OF THE INVENTION
Cables and particularly fiber optic cables have become a preferred transmission system for telecommunication and data communication. Fiber optic cables, for example, can contain many strands of optic fibers. These cables are generally installed underground inside a conduit. The conduit and the cable that runs through it are often laid in trenches and can extend for long distances. For purposes of maintenance, upgrading, and connection to the fiber optics, underground vaults are installed strategically along the path of the conduit and cable. Many cables and conduits may terminate or run through these vaults or other similar compartments. When a conduit terminates, but the cable continues its run, it is desirable to provide a seal between the cable and the conduit at the termination of the conduit.
A technical problem solved with the present invention is that fiber and/or copper cables need to enter an environmentally protected electronics enclosure. Their entry point must not compromise the environmental seal. The main issues are typically protection from Wind Driven Rain (WDR—hurricane type) and insects.
There are a number of solutions; however, none that meet all needs. For example:
One type is the rubber grommet. It typically is made of a rubber membrane that needs to be sliced to allow cable passage. The membrane does seal the cable entry to some extent, but not well enough to keep tiny insects out or WDR that may ride up the cables. To insure a proper seal, users add a liquid sealant such as RTV/caulking to completely seal these grommets. The more waterproof type only allows the cable to pass through. This does not work for cables that are pre-terminated/connectorized as are some in our case.
A particular example of the art is described in U.S. Pat. No. 4,842,364. In this case, the seal is formed by a gasket and supporting structure. The gasket and its supports can slide axially over the cable and into the conduit. However, this is not the case if the end of the cable is not accessible. In this case the gasket and its supports must be split or halved in order to surround the cable. The device described requires intricate fabrication techniques that utilize split threaded devices used for producing compression force on a gasket, thus causing the gasket to expand. The threaded nut is made in two halves and must be assembled around the cable. During fabrication of this nut, significant effort must be given to the correct timing of the threads so that when assembled the mating halves will produce a continuous thread. Assembly of the split halves can be difficult. In this prior art, the majority of the assembly of the seal occurs at the installation site, in the confines of an underground vault, which is difficult because the pieces are small and intricate. If the threaded parts are made of plastic, the tooling to produce these parts is intricate, complicated, and expensive. The amount of compression of the gasket in this and possible other prior art is dependent on how tightly threaded members are torqued. Since this torque is generally uncontrolled in the field, large forces may be transmitted which may damage the conduit and/or cable. Conversely, if too little torque is applied, the gasket may not seal as intended. Further, some prior art device use metal fasteners as part of the scheme to compress a gasket. Metal may corrode after time. These designs are optimized for water submersion and sealing individual cables. They do not seal well around more than one cable due to the required durometer of the gasket. In addition, the structure of the mechanism has to fit within the conduit severely restricting the size opening available for cable or cable with connector.
Accordingly, there remains a need for an improved device which can be easily installed around a fiber optic and/or copper cables before or after installation of the cables and can be as easily removed, and which has no corrodible components. Such a device limited tools to install and remove, and should be inexpensive, durable and efficient in sealing the cable from foreign substances.
SUMMARY OF THE INVENTION
Accordingly, it is the object of this invention to provide a simple, cost effective means to seal the area around a cable and the conduit in which the cable resides. The advantages can include: (a) ease of installation, (b) low cost, (c) complete assembly ease prior to installation, (d) controlled force that is transmitted to the cable and conduit, (e) improved sealing between cable and conduit, (f) resistance to chemicals in its environment, and (g) inherent corrosion resistance.
Still further objectives and advantages will become apparent from a consideration of the ensuing description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A shows a view of a cable entry seal device in an engaged position according to an embodiment of the present invention;
FIG. 1B shows a view of a cable entry seal device in an unengaged position according to an embodiment of the present invention;
FIG. 2A shows a view of a cable entry seal device in an engaged position according to another embodiment of the present invention; and
FIG. 2B shows a view of a cable entry seal device in an unengaged position according to another embodiment of the present invention.
DETAILED DESCRIPTION
Now referring to FIGS. 1A-1B of the drawings, a first embodiment of the present invention is schematically depicted therein.
The seal assembly is a sandwich or squeeze box seal design that can be placed over a cable and snapped/connected together around it. A connected seal assembly is shown in FIG. 1B . The two halves 11 , 13 have some form of foam rubber or similar resilient material 12 that wraps around the cable(s), which pass through the nut 15 and between the halves 11 , 13 , when compressed by the two halves 11 , 13 coming together. The material is contained in each half 11 , 13 and can be made from one or several layers and even pre-shaped if necessary. The closed unit 20 then fits into and seals a standard conduit opening/hole in a cabinet or enclosure and is fixed to the cabinet by the nut 15 and threading 21 . For an existing terminated cable, the nut currently applied around the cable is reused so that it is not required to disconnect the terminated cable. Standard size for the nut 15 and threading 21 is from the Approved American National Standard (ANSI) for electrical rigid conduit. This design lends itself to be used on any enclosure design that has standard conduit openings. Once tightened to the opening using a standard conduit fitting nut 15 , the unit 20 cannot be opened without loosening the nut 15 . This ensures less possibility for someone to tamper with the seal.
Now referring more particularly to FIG. 1A , the seal assembly 20 is shown in unassembled components. Each half of the assembly 11 , 13 includes half of the standard threadings 17 , 19 of the connected assembly thread 21 so when snapped/connected together a standard size nut can be screwed thereon. Each half 11 , 13 can be made from plastic, metal, or any other ridged material. The two halves 11 , 13 are held together by a snap assembly 14 , 16 . One of the halves 11 includes a pair of flexible arms 14 connected on opposing sides of the half 11 and which extend therefrom. The other half 13 includes a pair of bosses 16 connected on opposing sides of half 13 and adapted for engagement with the flexible arms 14 . When the two halves are compressed together, the flexible arms 14 snap over the bosses 16 . Thereafter, the nut 15 can be screwed onto the combined threadings 17 , 19 .
FIGS. 2A-2B illustrates another embodiment of the present invention. FIG. 2B shows a connected seal assembly 40 is shown in FIG. 1B . The two halves 31 , 33 have some form of foam rubber or similar resilient material 12 that wraps around the cable(s), which pass through the nut 15 and between the halves 31 , 33 , when compressed by the two halves 31 , 33 coming together. The material 12 is contained in each half 33 , 33 and can be made from one or several layers and even pre-shaped if necessary. The closed unit 40 then fits into and seals a standard conduit opening/hole in a cabinet or enclosure and is fixed to the cabinet by the nut 15 and threading 21 . Again, the standard size for the nut 15 and threading 21 is from the Approved American National Standard (ANSI) for electrical rigid conduit.
Now referring more particularly to FIG. 1A , the seal assembly 20 is shown in unassembled components. Each half of the assembly 11 , 13 includes half of the standard threadings 19 and a similar portion on top of the assembly 11 , of the connected assembly thread 21 so when snapped/connected together a standard size nut can be screwed thereon. Each half 11 , 13 can be made from plastic, metal, or any other ridged material. The two halves 11 , 13 are held together by a snap assembly 14 , 16 . One of the halves 11 includes a pair of flexible arms 14 connected on opposing sides of the half 11 and which extend therefrom. The other half 13 includes a pair of bosses 16 connected on opposing sides of half 13 and adapted for engagement with the flexible arms 14 . When the two halves are compressed together, the flexible arms 14 snap over the bosses 16 . Thereafter, the nut 15 can be screwed onto the combined threadings 19 and the similar portion on top of the assembly 11 .
The embodiments of the present invention can be differentiated from existing solutions in that it is a fast, very inexpensive way to get a watertight seal while still having the ability to use pre-terminated cables.
Some available solutions are time consuming in that they require a liquid sealant which also makes re-entry messy where the present invention requires no liquid sealant. Many of these must be custom designed for the specific application. Prior styles do not allow pre-terminated, or bundled, cables and therefore are not an option where the present invention allows for pre-terminated or bundled cables. Others also require special bulkhead designs or split openings rather than standard conduit sized holes where the present invention is designed for a standard conduit opening.
Various other modifications, changes, alterations and additions can be made in the improved assembly of the present invention. All such modifications, changes, alterations and additions as are within the scope of the appended claims form part of the present application.
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A seal assembly is provided to seal the area between a cable, containing optic fibers for example, and the terminal end of a conduit through which the cable runs. The seal assembly comprises an area of a resilient material and a supporting structure. The seal assembly, encompassing a cable, fits into and seals a standard conduit opening/hole in a cabinet or enclosure.
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CROSS-REFERENCES
[0001] This is a continuation of U.S. Ser. No. 13/224,338, filed Sep. 2, 2011, which is a continuation-in-part application of U.S. Ser. No. 12/790,398, filed May 28, 2010 the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to hydrogen generation devices. More particularly, the present invention relates to a hydrogen supplemental system that can be used with internal combustion engines for increased fuel efficiency and reduced carbon emissions.
[0004] 2. Description of the Related Art
[0005] There are a number of devices on the market that create HHO gas, otherwise known as Brown's gas, which is used as a supplement to gasoline and diesel engines. HHO gas consists of two parts hydrogen to one part oxygen. These devices typically comprise an electrolyzer which decomposes water into hydrogen and oxygen. An example is U.S. Pat. No. 4,368,696. These electrolyzers typically use an electrolyte, most notably KOH, Potassium hydroxide, or baking soda. A voltage is placed across the device to produce the HHO gas.
[0006] The main problem with most of these devices is that the energy required to produce the hydrogen creates a substantial load on the electrical system of the vehicle. Similar to running the air conditioner in any vehicle, the additional electrical load causes the miles per gallons to be reduced. Even though the hydrogen typically boosts the efficiency and miles per gallon of the vehicle, the additional electrical load on the vehicle to create the hydrogen is usually great enough to minimize or in many cases negate most or all of mileage gains of the vehicle.
[0007] Also, most HHO systems produce the hydrogen and oxygen in a combined gas stream. The hydrogen and oxygen gases are not generally separated from each other. In the case of modern gasoline powered vehicles, this extra oxygen is detected by the vehicle's oxygen sensors which communicate this extra oxygen level to an on-board computer, namely and Electronic Control Unit ECU of the vehicle. When the ECU detects this extra oxygen, it is a signal that the engine is running lean and the ECU adds more gasoline to the engine. This also negates most of the fuel efficiency gains.
[0008] Furthermore, HHO systems generally use either baking soda or Potassium Hydroxide KOH. KOH is generally preferred over baking soda because of its stability and because it causes less deterioration of stainless steel plates or other plates used in the electrolyzer. However, KOH has to be handled with care because it is caustic, and the crystals can be dangerous if not handled properly. The electrolyte normally has to be inserted into the unit at the proper proportions for optimum operation of the electrolyzer. Extreme care must be taken when using it. It is not the type of product you would generally like to put in the hands of an inexperienced consumer.
[0009] Complex installation is another issue with typical HHO systems. Space usually has to be found somewhere in the engine compartment or outside the vehicle. Since all vehicles are different, finding a suitable spot under the hood to install the device in many vehicles is next to impossible. Also, the systems are typically connected into the electrical systems of the vehicles which can cause blown fuses and a host of other problems if not installed properly. Hydrogen is only needed when the vehicle is actually running, not when the ignition is turned on. During the installation, care must be observed to make sure the electrical power is provided to the device only when the engine is running. Otherwise there can be hydrogen accumulation in the air intake. This further complicates the installation of these systems.
SUMMARY OF THE INVENTION
[0010] The present invention relates to a portable and compact, on-demand hydrogen supplemental system for producing hydrogen gas and injecting the hydrogen gas into the air intake of internal combustion engines, particularly for vehicles. Hydrogen and oxygen is produced by a fuel cell at low temperatures and pressure from water in a supply tank. The hydrogen gas and oxygen gas is passed back thru the supply tank for distribution and water preservation. The gases are kept separate by a divider in the tank and the water level in the tank. In the case of gasoline engines, the hydrogen gas is directed to the air intake of the engine while the oxygen gas is optionally vented to the atmosphere. The device can be powered by the vehicles alternator, a stand alone battery, waste heat or solar energy. The system utilizes a vacuum switch or other engine sensor that regulates power to the system and therefore hydrogen production for the engine only occurs when the engine is running. Therefore as the hydrogen is produced it is immediately consumed by the engine. No hydrogen is stored on, in or around the vehicle.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The foregoing and a better understanding of the present invention will become apparent from the following detailed description of example embodiments and the claims when read in connection with the accompanying drawings, all forming a part of the disclosure of this invention. While the foregoing and following written and illustrated disclosure focuses on disclosing example embodiments of the invention, it should be clearly understood that the same is by way of illustration and example only and the invention is not limited thereto, wherein in the following brief description of the drawings:
[0012] FIG. 1 is a detailed drawing of a portable hydrogen supplemental system showing a water tank and housing design according to the present invention.
[0013] FIG. 2 is a schematic showing a portable hydrogen supplemental system installed in a typical vehicle according to the present invention.
[0014] FIG. 3 is a diagram illustrating the operation and details of a PEM electrolyzer according to the present invention.
[0015] FIG. 4 is a diagram of another embodiment of the water tank 6 according to the present invention.
[0016] FIGS. 5A-B are diagrams of another embodiment of a mounting bracket 3 according to the present invention.
[0017] FIG. 6 is a diagram of an embodiment of the control circuit 50 according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0018] The present invention as will be described in greater detail below provides an apparatus, method and system, particularly, for example, a hydrogen supplemental system used to increase the fuel efficiency and reduce carbon emissions for internal combustion engines. The present invention provides various embodiments as described below. However it should be noted that the present invention is not limited to the embodiments described herein, but could extend to other embodiments as would be known or as would become known to those skilled in the art.
[0019] The present invention as shown in FIG. 1 provides a portable hydrogen supplemental system 1 which includes a housing unit 2 that can be secured in the trunk or other flat surface of a vehicle by mounting bracket 3 and fastening units 4 . Inside the housing unit 2 are a fuel cell 5 and a nonelectrolyte water tank 6 positioned above the fuel cell 5 arranged in such a manner as to supply nonelectrolyte water 7 to the fuel cell 5 by gravity. The nonelectrolyte water tank 6 is supported in the housing unit 2 above the fuel cell 5 by supporting means 8 . The housing unit 2 is designed to be readily removable from the mounting bracket 3 .
[0020] The nonelectrolyte water tank 6 includes a water supply fitting 9 positioned on the underside thereof connected to a tube or other supply means 10 that is in turn connected to water inlet fitting 11 on the fuel cell 5 . Nonelectrolyte water 7 is supplied to the fuel cell 5 by the supply means 10 . The fuel cell 5 also includes a hydrogen gas outlet fitting 12 and an oxygen gas outlet fitting 13 which are connected by tubes or additional supply means 14 and 15 to gas inlet fittings 16 on the underside of the nonelectrolyte water tank 6 . The nonelectrolyte water tank 6 includes at least one divider 17 that divides the tank 6 into at least two sections, a hydrogen section 18 and an oxygen section 19 . The divider 17 is formed along the inner wall of the tank 6 and extends to approximately ¼″ from the bottom surface 20 of the tank 6 . The tank 6 includes a fill spout 21 which permits the tank 6 to be filled with nonelectrolyte water. As nonelectrolyte water 7 is placed into the tank 6 , the tank 6 fills evenly on both sides of the divider 17 .
[0021] The fuel cell 5 , which is commonly known to produce electricity, is operated in reverse to produce hydrogen and oxygen gases. Thus, the fuel cell 5 essentially operates as an electrolyzer, which as described above decomposes nonelectrolyte water 7 into hydrogen and oxygen and is hereinafter referred to as an electrolyzer 5 . Nonelectrolyte water 7 fills the electrolyzer 5 from the nonelectrolyte water tank 6 and when a voltage, having positive and negative terminals, is placed across the electrolyzer 5 , hydrogen and oxygen gases are produced on opposing sides of the electrolyzer 5 .
[0022] According to the invention the electrolyzer 5 can, for example, be a proton exchange membrane or polymer electrolyte membrane (PEM) electrolyzer. A PEM electrolyzer includes a semipermeable membrane generally made from ionomers and designed to conduct protons while being impermeable to gases such as oxygen or hydrogen. This is their essential function when incorporated into a membrane electrode assembly (MEA) of a proton exchange membrane fuel cell or of a proton exchange membrane electrolyzer: separation of reactants and transport of protons.
[0023] As known an electrolyzer is a device that generates hydrogen and oxygen from water through the application of electricity and includes a series of plates through which water flows while low voltage direct current is applied. Electrolyzers split the water into hydrogen and oxygen gases by the passage of electricity, normally by breaking down compounds into elements or simpler products.
[0024] A PEM electrolyzer is shown in FIG. 3 . The PEM electrolyzer includes a plurality of layers which are non-liquid including at least two external layers and an internal layer, including external electrodes 41 disposed opposite to each other one of which is the anode 41 a and the other of which is the cathode 41 b , electrocatalysts 42 a and 42 b disposed respectively on the anode 41 a and the cathode 41 b, and a membrane 43 disposed between the electrocatalysts 42 a and 42 b. The PEM electrolyzer further includes an external circuit 44 which applies electrical power to the anode 41 a and the cathode 41 b in a manner such that electrical power in the form of electrons flow from the anode 41 a, along the external circuit 44 , to the cathode 41 b and protons are caused to flow through the membrane 43 from the anode 41 a to the cathode 41 b.
[0025] The efficiency of a PEM electrolyzer is a function primarily of its membrane and electro-catalyst performance. The membrane 43 includes a solid fluoropolymer which has been chemically altered in part to contain sulphonic acid groups, SO 3 H, which easily release their hydrogen as positively-charged atoms or protons H + : SO 3 H ->SO 3 − +H +
[0026] These ionic or charged forms allow water to penetrate into the membrane structure but not the product gases, namely molecular hydrogen H 2 and oxygen O 2 . The resulting hydrated proton, H 3 O + , is free to move whereas the sulphonate ion SO 3 − remains fixed to the polymer side-chain. Thus, when an electric field is applied across the membrane 43 the hydrated protons are attracted to the negatively charged electrode, known as the cathode 41 b. Since a moving charge is identical with electric current, the membrane 43 acts as a conductor of electricity. It is said to be a protonic conductor.
[0027] A typical membrane material that is used is called “nafion”. Nafion is a perfluorinated polymer that contains small proportions of sulfonic or carboxylic ionic functional groups.
[0028] Accordingly, as shown in FIG. 3 , nonelectrolyte water, H2O, enters the electrolyzer 5 and is split at the surface of the membrane 43 to form protons, electrons and gaseous oxygen. The gaseous oxygen leaves the electrolyzer 5 while the protons move through the membrane 43 under the influence of the applied electric field and electrons move through the external circuit 44 . The protons and electrons combine at the opposite surface, namely the negatively charged electrode, known as the cathode 41 b, to form pure gaseous hydrogen.
[0029] During operation of the electrolyzer 5 , a small amount of nonelectrolyte water 7 may be contained in hydrogen gas bubbles 22 and oxygen gas bubbles 23 as they emerge from the hydrogen outlet 12 and oxygen outlet 13 , respectively, of the electrolyzer 5 , and flow into the hydrogen side 18 and oxygen side 19 of the tank 6 . The bubbles rise (travel) thru the nonelectrolyte water 7 to upper air cavities 24 formed by the water level in the tank and the tank divider 17 . Since the hydrogen and oxygen may contain a small amount of nonelectrolyte water 7 , the hydrogen and oxygen gases are passed back through the nonelectrolyte water tank 6 for water preservation so that said small amount of nonelectrolyte water 7 will remain in the nonelectrolyte water tank 6 rather than be retained in the gases. The hydrogen and oxygen gases are kept separate from each other in the upper cavities 24 by the divider 17 and water level in the tank 6 . As the hydrogen gas and oxygen gas fill their respective upper cavities 24 , the gas flows out of the upper cavities thru fittings 25 in the case of hydrogen, and fitting 26 , in the case of oxygen on the upper side of the tank. The hydrogen gas flows thru tube 27 connected to hydrogen fitting 28 of the housing unit 2 . The oxygen flows thru tube 29 connected to fitting 30 of the housing unit 2 .
[0030] As shown in FIG. 2 , a vehicle 31 powered by a gasoline or diesel engine 32 is equipped with the portable hydrogen supplemental system 1 . Power is supplied to the portable hydrogen supplemental system 1 by a vehicle battery 33 connected to electrical wires 34 . The electrical circuit to the portable hydrogen supplemental system 1 includes a vacuum switch 35 , or other engine sensor and an operator controlled switch 36 which completes the electrical circuit to the portable hydrogen supplemental system 1 when the engine is running. Once power is supplied to the portable hydrogen supplemental system 1 , hydrogen gas flows thru hydrogen outlet tube 37 connected to hydrogen fitting 28 of the housing unit 2 to an air intake 38 of the vehicle's engine 32 . Oxygen gas flows thru oxygen outlet tube 39 and, in the case of gasoline engines with oxygen sensors, is vented to the atmosphere. The two gasses can optionally be combined for diesel engine vehicles or other internal combustion engines without oxygen sensors.
[0031] An alternative embodiment of the water tank 6 is illustrated in FIG. 4 . As per the water tank 6 as shown in FIG. 4 dividers 17 a and 17 b are provided at opposite ends of the tank 6 so as to divide the tank 6 into a hydrogen section 18 and an oxygen section 19 . Each divider 17 a,b is formed along the inner wall of the tank 6 and extends to approximately ¼″ from the bottom surface 20 of the tank 6 . As nonelectrolyte water 7 is placed into the tank 6 , the tank 6 fills evenly on both sides of each of the dividers 17 a and 17 b.
[0032] As described above according to the invention as the hydrogen gas and oxygen gas fill their respective upper cavities 24 , the gas flows out of the upper cavities thru fitting 25 in the case of hydrogen, and fitting 26 , in the case of oxygen on the upper side of the tank. Alternatively the fittings 25 and 26 can be replaced by gas collectors 45 and 46 . Each gas collector 45 , 46 is constructed to contain baffles 47 a and 47 b that serve to prevent water from splashing into or entering the tubes 27 and 29 . Each baffle 47 a,b is configured to extend perpendicularly from an inner surface of the gas collectors 45 and 46 . Particularly, baffle 47 a is configured to extend from a portion of the inner surface of a gas collector 45 , 46 opposite to another portion of the inner surface of the gas collector 45 , 46 from which baffle 47 b extends.
[0033] An alternative embodiment of the mounting bracket 3 is illustrated in FIGS. 5A-B . The mounting bracket 3 has formed therein oblong holes 48 positioned near the corners of the mounting bracket 3 for receiving screws/studs disposed on the undersigned of the housing unit 2 . The oblong holes 48 upon receiving the screws/studs disposed on the undersigned of the housing unit 2 allows for the housing unit 2 to be removably attached to the mounting bracket 3 . The housing unit 2 being removable from the mounting bracket 3 permits the user to remove the apparatus for servicing including adding water, performing repairs, exchanging parts, and the like.
[0034] The electrical circuit can, for example, be provided by a control circuit 50 as illustrated in FIG. 6 for controlling the portable hydrogen supplemental system 1 . The control circuit 50 includes a vacuum switch 35 , or other engine sensor, that provides a positive output when the engine is operating, an operator controlled switch 36 which provides the positive output from the vacuum switch 35 when the operator controlled switch 36 is moved to the on position, a global positioning system (GPS) 51 which provides a positive output when the speed of the automobile exceeds a predetermined level, AND gate 52 , or other such circuitry, that provides a positive output when both the operator controlled switch 36 and the GPS 51 outputs are positive, and a switch 53 which switches electrical power to the electrolyzer 5 when the AND gate 52 supplies a positive output, thereby causing the electrolyzer 5 to operate when the engine is operating and the speed of the automobile exceeds a predetermined level.
[0035] The portable hydrogen supplemental system 1 operates optimally in a gasoline powered engine when the load on the engine does not exceed a predetermined level and the amount of hydrogen produced by the Hydrogen supplemental system and supplied to the gasoline powered engine falls within a preset range.
[0036] In a gasoline powered engine the electrical power used by the portable hydrogen supplemental system is supplied by the engine alternator. As described above the electrical power is only supplied when the engine is operating and the speed of the automobile exceeds a predetermined level. Thus, the load placed on the engine by the portable hydrogen supplemental system 1 is related to the amount of electrical power drawn from the alternator as measured in amps. Optimally the portable hydrogen supplemental system 1 works best on a gasoline powered engine when the load on the engine does not exceed a current of 4 amps being drawn from the alternator, or if measured another way of 56 watts. It should be noted that the amount of amps or watts is dependent upon the size of the engine and alternator (four, six or eight cylinders, etc.). It should also be noted that diesel engines have a different optimal load setting.
[0037] Further, in a gasoline powered engine the optimal amount of hydrogen produced by the portable hydrogen supplemental system 1 and supplied to the gasoline powered engine falls within a preset range of 0.10-0.25 liters per minute.
[0038] Based on the above a gasoline powered automobile achieves the highest level of fuel efficiency measured in miles/gallon of gas when the load on the engine does not exceed 4 amps, or if measured another way of 56 watts, and the amount of hydrogen produced and supplied to the gasoline powered engine falls within a preset range of 0.10-0.25 liters per minute.
[0039] While the invention has been described in terms of its preferred embodiments, it should be understood that numerous modifications may be made thereto without departing from the spirit and scope of the present invention. It is intended that all such modifications fall within the scope of the appended claims.
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A portable, on-demand hydrogen generation system is provided for producing hydrogen and injecting the hydrogen as a fuel supplement into the air intake of internal combustion engines, more particularly to vehicles. Hydrogen and oxygen is produced with a fuel cell at low temperatures and pressure from water in a supply tank. The hydrogen and oxygen is passed back thru the supply tank for distribution and water preservation. The gases are kept separate by a divider in the tank and the water level in the tank. In the case of gasoline engines, the hydrogen is directed to the air intake of the engine while the oxygen is vented to the atmosphere. The device is optionally powered by the vehicle battery, a stand alone battery, waste heat of the internal combustion engine or solar energy. The system utilizes a vacuum switch or other engine sensor that permits power to the device and therefore hydrogen production only when the engine is in operation. Therefore, as the hydrogen is produced it is immediately consumed by the engine. No hydrogen is stored on, in or around the vehicle.
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This application is a continuation of application Ser. No. 08/255,043, filed Jun. 7, 1994 now abandoned.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a swash plate type compressor that uses no electromagnetic clutch.
2. Description of the Related Art
A clutchless type compressor, as disclosed in Japanese Unexamined Patent Publication No. 3-37378, does not use any electromagnetic clutch for either the transmission or cutting of power from an external driving source to the drive shaft of the compressor. The external driving source is coupled directly to the drive shaft.
Not using a clutch with direct connection between the driving source and drive shaft effectively eliminate-shocks caused by the ON/OFF action of the clutch. This tends to improve the comfort level of the driver during the vehicle's operation. The clutchless structure also contributes to a reduction in the overall weight and the cost of the cooling system.
In such a clutchless systems the compressor runs even when no cooling is needed. With such type of compressors, it is important that when cooling is unnecessary, the discharge displacement be reduced as much as possible in order to prevent the evaporator from undergoing frosting. Likewise, under these conditions, it is also important to stop the circulation of the refrigerant gas through the compressor, and its external refrigerant circuit.
The compressor described in Japanese Unexamined Patent Publication No. 3-37378, for example, is designed to block the flow of gas into the compressor's suction chamber from the external refrigerant circuit by the use of an electromagnetic valve. This valve selectively allows for the circulation of the gas through the external refrigerant circuit and the compressor. When gas circulation is blocked the pressure in the suction chamber drops and the control valve responsive to that pressure opens fully. The full opening of the control valve allows the gas in the discharge chamber to flow into the crank chamber, which in turn raises the pressure inside the crank chamber. The gas in the crank chamber is then supplied to the suction chamber. Accordingly, a short circulation path in formed which passes through the cylinder bores, the discharge chamber, the crank chamber, the suction chamber and back to the cylinder bores.
As the pressure in the suction chamber decreases, the suction pressure in the cylinder bores falls, causing an increase in the difference between the pressure in the crank chamber and the suction pressure in the cylinder bores. This pressure differential in turn minimizes the inclination of the swash plate which reciprocates the pistons. As a result, the compressor's discharge displacement, driving torque and power loan are minimized during times when cooling is unnecessary.
The aforementioned electromagnetic valve performs a simple ON/OFF action to instantaneously stop the gas flow from the external refrigerant circuit into the suction chamber. Naturally, when the valve is off, the amount of gas supplied into the cylinder bores from the suction chamber decreases drastically. This rapid decrease in the amount of gas flowing into the cylinder bores likewise causes a rapid decrease in the discharge displacement and discharge pressure. Consequently, the driving torque needed by the compressor is drastically reduced over a short period of time.
When the electromagnetic valve switches to an on position the amount of gas supplied to the cylinder bores from the suction chamber quickly increases as does the discharge displacement and discharge pressure. Consequently, the driving torque needed by the compressor undergoes a rapid rise over a short period of time.
This variation in torque, however, obstructs the suppression of shocks caused by the ON/OFF action that is the primary purpose of the clutchless system.
In the compressor disclosed in Japanese Unexamined Patent Publication No. 3-37378, the control valve controls the displacement of the compressor in response to the suction pressure. In this respect, the control valve is located downstream of the electromagnetic valve with the suction chamber disposed therebetween.
When the electromagnetic valve is closed to block the gas flow into the suction chamber, the gas pressure in the suction chamber remains low. Such a low gas pressure is an unreliable indicator of the cooling load.
Consequently, with compressors having the above construction, should the need for cooling arise or should the suction pressure undergo a rise in response to the cooling load, the control valve can not adequately respond. To overcome this shortcoming, a pressure sensor for detecting the suction pressure is used between the evaporator and the electromagnetic valve in the conventional compressor. In response to the cooling load, the pressure sensor provides a signal to the valve assembly, causing the electromagnetic valve to open.
The conventional compressor however requires the above described pressure sensor an well as its interconnections in order for the compressor to operate properly. This requirement effectively increases the conventional compressor's complexity as well as its price.
SUMMARY OF THE INVENTION
Accordingly, it is a primary objective of the present invention to suppress shocks caused by variation in driving torque needed by a compressor.
It is another objective of this invention to ensure adequate lubrication in a compressor.
It is a further objective of this invention to provide a compressor having a simple structure.
It is a still further objective of this invention to provide a compressor whose discharge displacement can be accurately regulated.
A compressor has a coolant gas passage selectively connected and disconnected with a coolant circuit apart from the compressor. A swash plate is supported on a drive shaft for integral rotation with inclining motion with respect to the drive shaft to drive the pistons. The swash plate is moveable between a maximum inclined angle and a minimum inclined angle. A disconnecting member disconnects the coolant circuit from the coolant gas passage when the swash plate is at the minimum inclined angle.
BRIEF DESCRIPTION OF THE DRAWINGS
The features of the present invention that are believed to be novel are set forth with particularity in the appended claims.
The invention, together with objects and advantages thereof, may beat be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:
FIGS. 1 through 8 illustrate a first embodiment of the present invention.
FIG. 1 is a side cross-sectional view of an overall compressor according to the first embodiment;
FIG. 2 is a cross section taken along the line 2--2 in FIG. 1;
FIG. 3 is a partial cross-sectional view showing the interior of a rear housing;
FIG. 4 is a side cross-sectional view of the whole compressor with its swash plate at the minimum inclined angle;
FIG. 5 is an enlarged fragmentary cross-sectional view showing the essential portions with a spool located at an open position;
FIG. 6 is an enlarged fragmentary cross-sectional view showing the essential portions with the spool located at a closed position
FIG. 7 is an enlarged fragmentary cross-sectional view of the essential portions, showing the spool located at the closed position with a deactivated solenoid;
FIG. 8A is a graph showing the results of an experiment on a variation in torque in the compressor of the present invention; and
FIG. 8B is a graph showing the results of an experiment on a variation in torque when the flow of a refrigerant gas into the compressor from an external refrigerant circuit is instantaneously stopped.
FIGS. 9 through 12 illustrate a second embodiment of the present invention.
FIG. 9 is a side cross-sectional view of an overall compressor according to the second embodiment;
FIG. 10 is a cross section taken along the line 10--10 in FIG. 9;
FIG. 11 is an enlarged fragmentary cross-sectional view showing the essential portions with a spool at an open position; and
FIG. 12 is an enlarged fragmentary cross-sectional view showing the essential portions with the spool at a closed position.
FIG. 13 is an enlarged fragmentary cross-sectional view showing the essential portions of another embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A swash plate type variable displacement compressor according to a first embodiment of the present invention will now be described referring to FIGS. 1 through 8.
As shown in FIGS. 1 and 4, a front housing 2 and a rear housing 3 are secured to a cylinder block 1. The cylinder block 1, front housing 2 and roar housing 3 constitute a housing 60 of the compressor. Secured between the cylinder block 1 and the roar housing 3 are a first plate 4, a second plate 5c, a third plate 5d and a fourth plate 6. A crank chamber 2a in defined in the front housing 2 between the cylinder block 1 and the front housing 2.
A ball bearing 7 is attached inside the front housing 2. A drive plate 8 is supported by the inner race of the ball bearing 7, and a drive shaft 9 is secured to the drive plate 8. By means of the drive plate 8, the ball bearing 7 receives the thrust load and radial load which act on the drive shaft 9.
The drive shaft 9 protrudes outside the front housing 2, with a pulley 10 fixed to the protruding portion. The pulley 10 is coupled to a vehicle's engine (not shown) via a belt 11. No electromagnetic clutch intervenes between the pulley 10 and the engine. A lip seal 12 is located between the drive shaft 9 and the front housing 2 to prevent a pressure leak from the crank chamber 2a.
A support 14 having a convex surface is supported on the drive shaft 9 in such a way as to be slidable along the axial direction of the drive shaft 9. The support 14 supplies support to swash plate 15 and allows it to tilt at the center of support 14 where the surface of swash plate 15 is concave.
As shown in FIGS. 1 and 2, a pair of stays 16 and 17 are securely attached to the swash plate 15, with pins 18 and 19 respectively secured to the stays 16 and 17.
The drive plate 8 has a protruding arm 8a in which a hole 8c is formed extending in the direction perpendicular to the axis of the drive shaft 9. A pipe-shaped connector 20, rotatable about its axis, is inserted in the hole 8c. A pair of holes 20a are formed in the cylindrical wall of the connector 20, and the pine 18 and 19 are slidably fitted in the respective holes 20a.
The swash plate 15 rotates together with the drive plate 8 by the coupling of the pine 19 and 19 to the connector 20, i.e., the swash plate 15 rotates with the drive shaft 9. When the swash plate 15 tilts, the connector 20 rotates about its axis and the pins 18 and 19 move in the holes 20a along their axes.
As shown in FIGS. 1, 4 and 5, a retainer hole 13 is formed in the center of the cylinder block 1 and extends along the axis of the drive shaft 9. A cylindrical spool 21 in retained slidable in the retainer hole 13. A flange 13a is formed on the inner wall of the retainer hole 13. A step 21c is formed at the outer wall of the spool 21. A spring 36 is disposed between the step 21c and the flange 13a to press the spool 21 toward the support 14.
The drive shaft 9 is fitted inside the spool 21. The drive shaft 9 is pressed via a ball 41 by a spring 42 which suppresses the movement of the drive shaft 9 in the thrust direction. A ball bearing 53 is located between the drive shaft 9 and the spool 21. The drive shaft 9 is supported on the inner wall of the retainer hole 13 via the ball bearing 53 and spool 21. The ball bearing 53 has an outer race 53a secured to the inner wall of the spool 21, and has an inner race 53b which is slidable on the outer surface of the drive shaft 9.
As shown in FIGS. 5 to 7, a restricting surface 55 is formed at the bottom of the retainer hole 13 of the spool 21. A step 9a (see FIGS. 6 and 7) is formed at the outer surf ace of the drive shaft 9. The spool 21 is movable between the position where it abuts the restricting surface 55 and the position where the inner race 53b of the ball bearing 53 abuts on the step 9a.
As shown in FIGS. 1, 3 and 4, a suction chamber 3a and a discharge chamber 3b are defined in the rear housing 3. A suction passage 54 is formed in the center of the rear housing 3 and communicates with the bottom of the retainer hole 13. Because the spool 21 abuts on the restricting surface 55, communication between the suction passage 54 and the retainer hole 13 is obstructed. The suction chamber 3a is connected via a passage 4c to the retainer hole 13.
When the spool 21 abuts the restricting surface 55, communication between the passage 4c and the suction passage 54 is obstructed. The suction passage 54, as illustrated is an inlet through which gas is supplied into the compressor. Additionally, when the spool 21 abuts surface 55, communication between the suction passage 54 and the retainer hole 13 is blocked. In case of either obstruction, the spool 21 is located at the downstream portion of the passage 54.
A pipe 56 is slidably provided on the drive shaft 9 between the support 14 and the ball bearing 53. An the support 14 moves toward the spool 21, the inner race 53b of the ball bearing 53 is pushed via the pipe 56 as shown in FIGS. 6 and 7. Consequently, the spool 21 moves toward the restricting surface 55 against the force of the spring 36.
The minimum inclined angle of the swash plate 15 is determined by the abutment of the spool 21 on the restricting surface 55. The minimum inclined angle of the swash plate 15 in slightly larger than 0 degree with respect to a plane perpendicular to the drive shaft 9. The maximum inclined angle of the swash plate 15 is determined by the abutment of a projection 8b of the drive plate 8 on the swash plate 15.
Pistons 22 are respectively placed in a plurality of cylinder bores 1a formed in the cylinder block 1. A pair of shoes 23 are fitted in a neck 22a of each piston 22. The swash plate 15 is placed between both shoes 23. The undulating movement of the swash plate 15, caused by the rotation of the drive shaft 9 is transmitted via the shoes 23 to each pistons 22. This causes linear reciprocation of the pistons 22.
As shown in FIGS. 1 and 3, an inlet port 4a and a discharge port 4b are formed in the first plate 4. An inlet valve 5a is provided on the second plate 5c, and a discharge valve 5b is provided on the third plate 5d.
The gas in the suction chamber 3a pushes the inlet valve 5a and enters the cylinder bore 1a through the inlet port 4a in accordance with the backward movement of the piston 22. The gas that has entered the cylinder bore 1a is compressed by the forward movement of the piston 22, and in then discharged to the discharge chamber 3b via the discharge port 4b while pushing the discharge valve 5b. Any excessive opening motion of the discharge valve 5b is inhibited by a retainer 6a on the fourth plate 6.
The suction passage 54 and a discharge port 1c, from which the gas from the discharge chamber 3b is discharged, are connected by an external refrigerant circuit 49. Provided in the circuit 49 are a condenser 50, an expansion valve 51 and an evaporator 52. The expansion valve 51 controls the amount of flowing gas in accordance with a change in gas pressure on the outlet side of the condenser 50. The pressure in the passage from the evaporator 52 to the cylinder bores 1a is a low value close to the suction pressure.
The inclined angle of the swash plate 15 varies in accordance with the changing pressure differential between the pressure in the crank chamber 2a and the suction pressure in each cylinder bore 1a. As the inclined angle of the swash plate 15 varies, the stroke of the piston 22 changes, thus changing the displacement of the compressor. The pressure in the crank chamber 2a is controlled by a displacement control valve 24 attached to the rear housing 3. The crank chamber 2a is connected to the suction chamber 3a via a passage 1b that has the function of a restriction.
The structure of the displacement control valve 24 will be described below with reference to FIGS. 5 through 7. A guide cylinder 27 is fixed to the hollow portion of a bobbin 26 that supports a solenoid 25. A fixed iron core 28 it fixed inside the guide cylinder 27. A movable iron core 29 in placed in the guide cylinder 27. A spring 30 is placed between the fixed core 28 and the movable core 29. The movable core 29 is urged away from the fixed core 28 by the force of the spring 30.
A valve housing 31A is secured via a block 32 to the bobbin 26. First and second chambers 61 and 43 are defined in the valve housing 31A, and are connected together by a passage 31d. A spherical valve assembly 33 is placed in the first chamber 61 that has a seat 38 secured thereto. A hole 38a, through which gas passes, is formed in the seat 38. A spring 39 and a seat 40 are provided between the seat 38 and the valve assembly 33. The valve assembly 33 receives the force of the spring 39 that acts in the direction to close the passage 31d.
A metal bellows 44, having an air tight interior, is disposed in the second chamber 43, and is fixed to the movable core 29. A plate 45 is fixed to the bellows 44 which in urged to expand by spring 47. A rod 48 is provided between the plate 45 and the valve assembly 33.
A first port 31a is formed in the first chamber 61, and a second port 31b is formed in the second chamber 43. A third port 31c is formed in the passage 31d. The first port 31a is connected via a passage 34 to the discharge chamber 3b. The second port 31b 1a connected via a passage 35 to the suction passage 54 at the upstream of the spool 21. The third port 31c is connected via a passage 37 to the crank chamber 2a.
The solenoid 25 is controlled by a computer 93. The computer 93 activates the solenoid 25 when an air conditioning switch 57 for activating an air conditioner is turned on or when an accelerator switch 58 is turned off. The computer deactivates the solenoid 25 when the air conditioning switch 57 in turned off or when the accelerator switch 58 is turned on. The accelerator switch 58 is turned on when the acceleration pedal in thrust down to increase the engine speed. The accelerator switch 58 is provided to improve the fuel economy.
In FIGS. 5 and 6, the solenoid 25 is excited. With the solenoid 25 excited, the movable core 29 is attracted to the fixed core 28 against the force of the spring 30, as shown in FIG. 5. In FIG. 7, the solenoid 25 is deactivated, With the solenoid 25 deactivated, the movable core 29 is separated from the fixed core 28 due to the force of the spring 30.
With the solenoid 25 activated, the movable core 29 is attracted to the fixed core 28, and the control valve 24 functions as follows. When the suction pressure of the gas, which is supplied via the passage 35 to the second chamber 43 from the suction passage 54, is high the bellows 46 contracts. This occurs when the cooling load is high. The contracting motion is transmitted via the rod 48 to the valve assembly 33 so that the valve assembly 33 moves in a direction that reduces the amount with which the displacement control valve 24 opens.
With a small opening of the valve 24, the amount of gas flowing into the crank chamber 2a from the discharge chamber 3b via the passage 34, first port 31a, hole 38a, passage 31d, third port 31c and passage 37 decreased. Consequently, the pressure in the crank chamber 2a falls.
When the cooling load is high, the suction pressure in the cylinder bores 1a is high. This decreases the difference between the pressure in the crank chamber 2a and the suction pressure in the cylinder bores 1a. As a result, the inclined angle of the swash plate 15 increases an shown in FIGS. 1 and 5.
When the suction pressure is low or the cooling load in low, the bellows 46 expands. Consequently, the valve assembly 33 moves in the opening direction to increase the amount of gas flowing into the crank chamber 2a from the discharge chamber 3b. This raises the pressure in the crank chamber 2a.
When the cooling load is low, the suction pressure in the cylinder bores 1a is low so that the difference between the pressure in the crank chamber 2a and the suction pressure in the cylinder bores 1a increases. As a result, the inclined angle of the swash plate 15 becomes smaller.
When the suction pressure becomes very low or when the cooling load does not exist, the valve assembly 33 approaches the maximum opening position as shown in FIG. 6. When the air conditioning switch 57 in turned off or the accelerator switch 58 in turned on to deactivate the solenoid 25, the movable core 29 moves away from the fixed core 28 due to the force of the spring 30. This causes the valve assembly 33 to move to the maximum opening position as shown in FIG. 7.
In the maximum open state as shown in FIG. 7 or in a state close to the maximum open state as shown in FIG. 6, a large amount of the gas in the discharge chamber 3b flows into the crank chamber 2a. The pressure in the crank chamber 2a therefore rises to the maximum level, and the swash plate 15 moves toward the minimum inclination.
As the swash plate 15 moves toward the minimum inclination, the support 14 moves toward the spool 21, causing the pipe 56 to push the inner race 53b of the ball bearing 53. As a result, the spool 21 moves toward the restricting surface 55.
The approach of the spool 21 to the restricting surface 55 restricts the area of the gas-passing cross section between the suction passage 54 and the suction chamber 3a. This restriction reduces the amount of gas flowing into the suction chamber 3a from the suction passage 54. The amount of the gas supplied into the cylinder bores 1a from the suction chamber 3a also decreases, thus reducing the discharge displacement. An a result, the discharge pressure falls, reducing the driving torque-needed by the compressor.
Even If the valve assembly 33 is moved to the opening position and a large Amount of gas in the discharge chamber 3b enters the crank chamber 2a, there is a certain amount of time that it takes to increase the pressure in the crank chamber 2a. Thus, the swash plate 15 gradually moves toward the minimum inclination. Likewise, the change in the discharge displacement of the compressor will not experience rapid changes and the driving torque needed by the compressor. It is therefore possible to prevent a large change in the compressor's torque.
When the small-diameter portion, 21b, of the spool 21 abuts on the restricting surface 55, the gas flow to the suction chamber 3a from the external refrigerant circuit 49 is blocked and the swash plate 15 moves to a minimum inclined angle.
Since the angle of the swash plate 15 is not 0 degrees at this time, the piston 22 reciprocates even in this condition to discharge the gas to the discharge chamber 3b from the associated cylinder bore 1a. With the gas flow to the suction chamber 3a from the external refrigerant circuit 49 so blocked, the gas discharged to the discharge chamber 3b from the associated cylinder bore 1a flows into the crank chamber 2a via the path of the passage 34, port 31a, hole 38a, port 31c and passage 37. The gas in the crank chamber 2a enters the suction chamber 3a via the restricting passage 1b. The gas in the suction chamber 3a is supplied to the cylinder bores 1a and is discharged to the discharge chamber 3b.
With the swash plate 15 at a minimum inclined angle, a short gas circulation circuit consisting of the cylinder bore 1a, discharge chamber 3b, passage 34, control valve 24, passage 37, crank chamber 2a, passage 1b, suction chamber 3a and cylinder bore 1a is formed in the compressor. Thus, the movable portions, such as the ball bearings in the compressor, are lubricated with the lubricating oil suspended in the circulating gas, ensuring the adequate continuous operation of the compressor.
As the gas circulates through the circulation circuit, having the restrictions explained above, there are pressure differences which are created among the discharge chamber 3b, crank chamber 2a and suction chamber 3a. The gas inside the compressor will not flow out to the external refrigerant circuit 49. Consequently, the frosting of the evaporator 52 is unlikely.
Since the pipe 56 is held between the support 14 and the inner race 53b, the pipe 56 rotates with the drive shaft 9. Due to the contact between the pipe 56 and the inner race 53b of the ball bearing 53, the drive shaft 9, support 14, pipe 56 and inner race 53b rotate together, causing no friction among the support 14, pipe 56 and inner race 53b.
When the suction pressure rises due to an increase in cooling, load, the increased suction pressure is transmitted to the second chamber 43 via the suction passage 54 and passage 35. Consequently, the bellows 46 contracts and the valve assembly 33 closes the passage 31d. When the air conditioning switch 57 is turned on or the accelerator switch 58 is turned off on the other hand, the solenoid 25 in activated, causing the movable core 29 to be attached to the fixed core 28. The bellows 46 and the rod 48, therefore, move together with the movable core 29, causing the valve assembly 33 to move in the direction to obstruct the passage 31d due to the force of the spring 39.
When the valve assembly 33 blocks the passage 31d, the path from the discharge chamber 3b to the crank chamber 2a is closed. Consequently, the pressure in the crank chamber 2a gradually decreases, moving the swash plate 15 to a maximum inclined angle from a minimum inclined angle.
The movement of the swash plate 15 causes the support 14 to move in the same direction. Due to the force of the spring 36, the spool 21 moves in response to the movement of the support 14. As a result, the distal end of the spool 21 moves away from the restricting surface 55.
The separation of the spool 21 increase the cross sectional area of the passage between the suction passage 54 and the suction chamber 3a. The increased cross-sectional area increases the amount of gas that can flow into the suction chamber 3a from the suction passage 54. Accordingly, the amount of the gas supplied into the cylinder bores 1a from the suction chamber 3a also increases, thus increasing the discharge displacement. As a result, the discharge pressure rises, increasing the driving torque needed by the compressor.
Even in this case, the rising of the pressure in the crank chamber 2a taken place gradually, and the swash plate 15 moves toward the maximum inclination gradually. The increase of the discharge pressure changes slowly, thus eliminating the need for quick changes to be made to the torque needed by the compressor. It is therefore possible to prevent shocks caused by a large change in torque from occurring in the compressor.
FIG. 8A presents a graph showing the results of an experiment on variations made to the torque of the compressor according to this embodiment. A curve 100 is a torque variation curve, a curve 101 represents a change in pressure in the suction chamber 3a, a curve 102 represents a change in pressure in the discharge chamber 3d, and a curve 103 represents a change in pressure in the crank chamber 2a. The horizontal scale α represents the time, the vertical scale β represents the pressure and the vertical scale γ represents the torque. In this graph, the deactivated solenoid 25 is activated at time η.
The graph in FIG. 8B shows the results of an experiment on a variation in torque when the flow of the refrigerant gas into the suction passage 54 from the external refrigerant circuit 49 in the compressor of this embodiment is completely obstructed at time η.
The action of restricting the supply of the intake gas in the compressor disclosed in Japanese Unexamined Patent Publication No. 3-37378 in the same as that where the flow of the refrigerant gas into the suction passage 54 from the external refrigerant circuit 49 in completely obstructed. A curve 100' is a torque variation curve, a curve 101' represents a change in pressure in the suction chamber 3a, a curve 102' represents a change in pressure in the discharge chamber 3d, and a curve 103' represents a change in pressure in the crank chamber 2a.
It is apparent from the comparison between the two graphs that the change in the discharge pressure curve 102 immediately after time η is smaller and gentler than that in the discharge pressure curve 102'. Likewise, the change in the torque variation curve 100 immediately after time η is smaller and gentler than that in the torque variation curve 100'.
It is apparent from the experimental results that the changes in driving torque and shocks originating therefore in compressors according to the present invention is a vast improvement over that of the compressor as disclosed in Japanese Unexamined Patent Publication No. 3-37378. In the No. 3-37378 publication, when the electromagnetic valve is deactivated, the pressure in the suction chamber remains low and the refrigerant gas in the suction chamber is not indicative of the cooling load. A pressure sensor for detecting the suction pressure 1a thus provided between the evaporator and the electromagnetic valve in the conventional compressor.
According to this embodiment, by contrast, the suction-pressure introducing position of the displacement control valve 24a, which responds to the suction pressure, is located upstream of the position at which the gas flow is blocked by the spool 21. The control valve 24a can thus always respond to a change in cooling load. When the cooling load is produced and the suction pressure rises, the control valve 24a instantaneously responds to the rise in suction pressure, consequently the inclined angle of the swash plate 15 increases from a minimum inclined angle unless the solenoid 25 is deactivated.
In short, the compressor according to this embodiment needs no pressure sensor between the evaporator and the electromagnetic valve and thus has a simpler structure than conventional compressors.
A second embodiment of the present invention will now be described referring to FIGS. 9 through 12.
The second embodiment does not have the passage 1b provided between the suction chamber 3a and the crank chamber 2a.
A passage 59 formed in the axial position of the delve shaft 9, has an inlet port 59a open to the crank chamber 2a in the vicinity of the lip seal 12, and an outlet port 59b open to the area where the spool 21 slides in contact with the drive shaft 9. The opening of the passage 59 at one end of the drive shaft 9 is closed by the ball 41 and spring 42.
As shown in FIG. 9, an annular passage 80 is formed in the inner wall of the spool 21, and the outlet port 59b of the passage 59 is always connected to the passage 80 in the spool 21.
Formed in the vicinity of the step 21c of the spool 21 is a passage 64 penetrating through the spool 21. The passage 64 allows the passage 80 to communicate with the retainer hole 13. The retainer hole 13 and the passage 4c are connected together via a restricting passage 62. The outlet port of the restricting passage 62 is located downstream of the restricting surface 55.
In other words, the crank chamber 2a communicates with the suction chamber 3a via a passage 63 formed by the passages 59, 80, and 64, the retainer hole 13 and the restricting passage 62. The gas in the crank chamber 2a flows out into the suction chamber 3a via the passage 63. The cross-sectional area of the restricting passage 62, which constitutes a part of the passage 63, is smaller than the cross-sectional areas of the passages 59, 80 and 64 The gas flow undergoes a restriction in the restricting passage 62.
The outlet port of the control passage 37 is directed to the peripheral portion of the swash plate 15.
When the inclined angle of the swash plate 15 is at a minimum, a circulatory system is formed among the cylinder bore 1a, the discharge chamber 3b, the passage 34, the passage in the control valve 24, the passage 37, the crank chamber 2a, the passage 63, the suction chamber 3a, and the cylinder bore 1a.
To properly control the inclined angle of the swash plate 15, the pressure in the crank chamber 2a should be set to the proper level. This requires that the amount of gas flowing into the suction chamber 3a from the passage 63 be accurately regulated. The amount of the gas flow is regulated by the restricting passage 62 which is a part of the pressure discharge passage 63. If gas leaks in somewhere in the pressure discharge passage 63, however, the inclined angle of the swash plate 15 cannot be controlled properly.
The gas leak from the pressure discharge passage 63 is likely to occur at the clearance between the outer surface of the drive shaft 9 and the inner wall of the spool 21. To prevent the gas leakage, the outer surface of the drive shaft 9 should contact the inner wall of the spool 21 as closely as possible. This structure increases the friction between the drive shaft 9 and the spool 21. In the clutchless compressor, the drive shaft 9 keeps rotating unless the external driving source is stopped. The large friction between the drive shaft 9 and the spool 21 thus causes wearing or burning therebetween.
If burning occurs between the drive shaft 9 and the spool 21, the spool 21 cannot slide, disabling the control on the inclined angle of the swash plate 15. If the drive shaft 9 and the spool 21 wear out, the gas leakage from the pressure discharge passage 63 increases no that the inclined angle of the swash plate 15 in turn cannot be accurately controlled.
According to the second embodiment, when the spool 21 does not abut the restricting surface 55, the open position, the gas in the crank chamber 2a flows into the suction chamber 3a via the pressure discharge passage 63. When the spool 21 abuts the restricting surface 55, the gas in the discharge chamber 3b circulated through the passage 34, control valve 24, control passage 37, crank chamber 2a, passage 63, suction chamber 3a and cylinder bore 1a and returns to the discharge chamber 3b. The passage 80 which is a part of the passage 63 is located in the slidable area between the drive shaft 9 and the spool 21. This slidable area is lubricated with the lubricating oil that flows together with the gas.
Therefore, the wearing or burning of the drive shaft 9 and the spool 21 in prevented.
The lubricating oil enters between the drive shaft 9 and the spool 21 to enhance the sealing therebetween, so that the gas leakage from between the drive shaft 9 and the spool 21 is prevented. The adequate lubrication of the slidable area between the drive shaft 9 and the spool 21 contributes to the smooth sliding of the spool 21. This promotes smooth gas flow restriction and increasing of the cross-sectional area of the restricting passage 62.
In addition, due to the fact that the retainer hole 13 is a part of the passage 63 and that the slidable area between the spool 21 and the cylinder block 1 is lubricated with oil carried along with the refrigerant gas, the sliding action of the spool 21 becomes smoother.
According to the second embodiment, as described above, the wearing or burning of the drive shaft 9 and spool 21 can be prevented and the smooth movement of the spool 21 is enhanced so that the inclined angle of the swash plate 15 can be more accurately controlled. An enhanced compressor displacement control is therefore possible.
Since the inlet port 59a of the passage 63 is located near the lip seal 12, the lubricating oil, and refrigerant gas flowing through the passage 63 improves the sealing performance of the lip seal 12. Moreover, since the outlet port of the control passage 37 in directed to the peripheral portion of the swash plate 15, the gas flowing into the crank chamber 2a from the passage 37 hits the sliding portions between the swash plate 15 and the shoes 23. The gas thereby lubricates these sliding portions.
Although only two embodiments of the present invention have been described herein, it should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Particularly, it should be understood that the following modes are to be applied.
(1) The support and the spool may be integrated.
(2) To effect the shifting of the spool between the position where a passage from the external refrigerant circuit to the suction chamber in closed and the position where that passage is opened, the pressure in the crank chamber may directly act on the spool. That is the spool may be shifted in accordance with the difference between the pressure in the crank chamber and the suction pressure, rather than the inclined angle of the swash plate.
(3) An embodiment as shown in FIG. 13 may be worked out. In this embodiment, the passage 80 in the inner wall of the spool 21 communicates with the clearance between the outer race 53a and inner race 53b of the ball bearing 53. This allows oil communication without the need of the passage 59 in the drive shaft 9. The gas in the crank chamber 2a flows into the passage 80 through the clearance between the outer race 53a and inner race 53b. The slidable area between the drive shaft 9 and the spool 21 can be lubricated sufficiently as per the previous embodiments, however, this embodiment ensures better lubrication of the ball bearing 53 than the previous embodiments.
Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive and the invention in not to be limited to the details given herein, but may be modified within the scope of the appended claims.
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A compressor has a refrigerant gas passage selectively connected to and disconnected from a refrigerant circuit apart from the compressor. A swash plate is supported on a drive shaft for integral rotation with inclining motion with respect to the drive shaft to drive the pistons. The swash plate is moveable between a maximum inclined angle and a minimum inclining angle. A disconnecting member disconnects the refrigerant circuit from the refrigerant gas passage when the swash plate is at the minimum inclined angle.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an aerodynamic control system for structural stability augmentation of a forward swept wing aircraft.
2. Statement of Prior Art
Forward swept wings of metal are limited in their use due to the static stability phenomenon of divergence at high speed flight conditions. Making the wing out of composite materials offers relief from this phenomenon. However, forward swept wings made from composites are still quite flexible when installed on aircraft. This has led to the observation of a newly discovered dynamic stability phenomenon called rigid body (whole vehicle) structural mode coupling. This occurs as a result of coupling between properly phased wing bending and the aircraft rigid body pitching mode when the frequencies of the two modes are close together. The consequences of rigid body structural mode coupling (also known as rigid body/wing bending flutter) are structural dynamic instability that can be critical with certain aircraft configurations, a degradation in aircraft handling and ride qualities, and increased wing design loads for gusts.
Stability augmentation systems for augmenting whole vehicle motion response are well known in the art. One such system is disclosed in U.S. Pat. No. 4,171,115 to Osder. Another such system is disclosed in U.S. Pat. No. 3,819,135 to Foxworthy, et al. An application of such a system to a forward swept wing aircraft is disclosed in U.S. Pat. No. 2,420,932 to Cornelius.
Augmentation systems have also been used on flexible aircraft to control structural motion and provide stability. Examples of such systems are disclosed in U.S. Pat. Nos. 3,412,961 and 3,279,725. U.S. Pat. No. 3,902,686 discloses a structural mode control system having sensing elements to operate control force application devices such as aerodynamic control vanes to obtain structural damping. Sensing elements are located near control force application points. In U.S. Pat. No. 3,347,498, a system is disclosed which utilizes accelerometers employed on the wing and fuselage to sense structural accelerations of the wing and to operate wing control surfaces to reduce wing structural stress. Rigid body motion and structural motion are separated by appropriate placement of sensors. A flutter suppression system is disclosed in U.S. Pat. No. 3,734,432. Here one or more pairs of leading and trailing edge control surfaces are operated by a stability augmentation system to suppress flutter. De-stabilizing effects on the rigid body mode are opposed by additional leading and trailing edge control pairs on the horizonal tail or canard.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan view of a forward swept wing aircraft equipped with the stability augmentation system;
FIG. 2 is a block diagram illustrating the stability augmentation system; and
FIG. 3 is a block diagram of the stability augmentation system incorporated with a whole vehicle stability augmentation system.
While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to those embodiments. On the contrary, it is intended to cover all alternatives, modifications, and equivalents which may be included within the spirit and scope of the invention as defined by the appended claims.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a stability augmentation system for a forward swept wing aircraft which suppresses wing flexure and rigid body/wing bending flutter with minimal resulting rigid body motion inducing inputs.
It is another object of this invention to provide a stability augmentation system for a forward swept wing aircraft that improves vehicle handling qualities.
It is yet another object of the present invention to provide a stability augmentation system for a forward swept wing aircraft which improves ride qualities.
It is still another object of the present invention to provide a stability augmentation system for a forward swept wing aircraft that reduces wing design structural loads for gusts and turbulence.
Briefly, in accordance with the invention, there is provided a stability augmentation system for a forward swept wing aircraft that uses active controls to suppress rigid body/wing bending flutter and wing flexure. Flight control surfaces are mounted on each wing in a position to straddle an axis substantially perpendicular to the fuselage center line and which passes through the aircraft's nominal center of gravity. Wing sensors are mounted near each of the control surfaces to provide signals indicative of wing motion. Sensors are also mounted on the fuselage to provide signals indicative of fuselage motion. A computer means is responsive to the signals from the sensors to generate control signals indicative of wing structural motion. A control means receives the control signals and moves the control surfaces proportional to the control signals such that wing flexure and rigid body/wing bending flutter are suppressed. The control surfaces can be operated differentially to compensate for asymmetric wing structural motion.
Other objects and advantages of the invention will be apparent upon reading the following detailed description and upon reference to the drawings.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIG. 1, there is shown an aircraft generally indicated at 10 having forward swept wings 12 and 13, and fuselage 14. Wing 12 is on the right or starboard side of the aircraft while wing 13 is on the left or port side of the aircraft. Aircraft 10 will normally employ canard surfaces 16 and 17. Positioned on wing 12 along the trailing edge are moveable flight control surfaces 18 and 20. Similarly, positioned on wing 13 along the trailing edge thereof are moveable flight control surfaces 19 and 21. In accordance with the present invention, control surfaces 18 and 19 function as elevons while control surfaces 20 and 21 act as ailerons and as a means to suppress wing flexure and rigid body/wing bending flutter.
Control surfaces 20 and 21 are optimally located at or near the wing tips 22 and 23 respectively. The purpose is two-fold. First, on a forward swept wing aircraft, outboard control surface effectiveness increases with dynamic pressure (which is opposite to the loss of effectiveness on aft swept wings). This is significant since rigid body/wing bending flutter on typical forward swept wing aircraft occurs with increasing speed (and dynamic pressure). As such, control surface deflection is more effective and produces a more rapid response. Secondly, by virtue of the geometry of forward swept wing aircraft, control surfaces near the wing tip will normally straddle the nominal aircraft center of gravity indicated at 24. This is shown in FIG. 1 by an axis indicated at 25 which is perpendicular to the fuselage center line 26 and which passes through the aircraft's center of gravity 24 and control surfaces 20 and 21. As such, when surfaces 20 and 21 are deflected to suppress rigid body/wing bending flutter in accordance with the present invention, there will be substantially no resulting rigid body pitch motion inducing input. Therefore, compromise of handling qualities is minimized.
While the control surfaces 20 and 21 are illustrated to be positioned on the trailing edge of the wings 12 and 13, they could also be positioned on the leading edge of the wings and serve the same purposes in accordance with the present invention if aircraft geometry was such that they straddled the aircraft's nominal center of gravity 24. The term "nominal" is used since during flight, the aircraft's actual center of gravity will shift, i.e., due to fuel usage. Accordingly, what is meant by the term "nominal" is the average location of the center of gravity during flight.
Sensor 30 is positioned on wing 12 near control surface 20, i.e., at approximately the control force application point. This principal is described in U.S. Pat. No. 3,902,686. Likewise, sensor 32 is positioned on wing 13 near control surface 21. Sensors 34 and 36 are positioned on the right and left side of the fuselage respectively. Optimally, sensors 30, 32, 34, and 36 will all lie substantially in a plane indicated at 40 perpendicular to the fuselage center line 26.
Sensors 30, 32, 34, and 36 are preferably linear accelerometers which are positioned to measure vertical acceleration. Thus, sensor 30 measures vertical acceleration of wing 12, sensor 32 measures vertical acceleration of wing 13, and sensors 34 and 36 measure vertical fuselage acceleration.
Turning now to FIG. 2, there is shown a block diagram of the present stability augmentation system. In response to an upset excitation, such as a gust, on aircraft 10, sensors 30 and 32 produce signals proportional to movement of wings 12 and 13 respectively. From the same upset excitation on aircraft 10, the sensors 34 and 36 on the fuselage also produce signals. These signals are however indicative of fuselage motion.
The signals from sensors 30, 32, 34, and 36 are transmitted to a computer 50. The signals are combined (subtracted) in the computer 50 to compute the wing structural motion, i.e., the difference between the vertical wing acceleration and the vertical fuselage acceleration. In the symmetric case, wing structural motion of wings 12 and 13 is equal. In the asymmetric case, wing structural motion of the wings is unequal. In order to correctly address each of there conditions, the computer 50 combines the signals from sensors 32 and 36 to obtain the structural motion of wing 13 and combines the signals from sensors 30 and 34 to obtain the structural motion of wing 12. Signals representative of structural motion for each wing are generated which are shaped and filtered to produce correct phasing and gain adjustments.
Computer 50 transmits a control signal representative of structural motion of wing 12 to an actuator 52. Computer 50 also transmits a second control signal indicative of structural motion of wing 13 to actuator 54. Actuator 52 rotates control surface 20 proportional to the control signal it receives. Similarly, actuator 54 rotates control surface 21 in proportion to the control signal it receives from computer 50. In the symmetric case, control surfaces 20 and 21 are rotated equally. In the asymmetric case, control surfaces 20 and 21 would be rotated differentially. The rotation of surfaces 20 and 21 in accordance with the respective control signals from computer 50 is such as to oppose or suppress wing flexure and consequently rigid body/wing bending flutter which may otherwise occur, i.e., by damping out the oscillations due to wing structural motion and thereby avoiding the destabilizing effects of its combination with rigid body oscillation.
In the view of the above, it should be understood that the present system compensates for aircraft roll movements. Thus, vertical acceleration as computed by respective wing and fuselage sensor pairs, e.g., 32 and 36, will be varied by an equal amount due to the roll movement. As such, the relative motion (of wing verses fuselage) as determined by the respective pairs of fuselage and wing sensors will be unaffected by an aircraft roll movement.
While the present stability augmentation system can be a stand-alone system, it is optimally employed as an addition or enhancement to a basic (primary) stability augmentation system which is concerned with whole vehicle stability. A combined system is illustrated in FIG. 3. It has been determined that primary system control surface movement requirements are reduced as a result of the enhancement, thereby reducing power requirements. With the primary system, a number of sensors to determine change in attitude of the aircraft are employed. Such sensors would be positioned in suitable places on aircraft 10. Typically included would be a vertical accelerometer 60, a pitch gyro 62, a lateral accelerometer 64, a yaw gyro 66, and a roll gyro 68. These sensors transmit signals to a computer 70. These signals are combined, shaped, and filtered in the computer to generate attitude control signals. The attitude signals are transmitted to actuators 72 and 74 to rotate elevons 18 and 19 respectively as appropriate to stabilize the aircraft in the pitch mode and to actuators 52 and 54 to rotate control surfaces 20 and 21 to stabilize the aircraft in the roll mode. The other sensors and controls illustrated in FIG. 3 work as described previously with respect to FIG. 2 (with computer 70 also performing the same functions as computer 50). As control surfaces 20 and 21 are utilized for both roll control and rigid body/wing bending flutter suppression, the attitude control signals which are transmitted from computer 70 to actuators 52 and 54 are combined with the respective flutter control signals from computer 70 to actuators 52 and 54.
While the present invention solves the problem of rigid body/wing bending flutter on forward swept wing aircraft, it has been discovered that there are additional important benefits. The impact of wing flexibility on a forward swept wing aircraft is such that the static lifting capability at a given attitude to the wind will be greatly increased, e.g., by a factor of 1.5 over a rigid wing, whereas on an aft swept wing at the same flight conditions wing lifting capabilities are greatly reduced, e.g., to a factor of about 0.6 over a rigid wing. This increased wing lift capability and wing flexibility on a forward swept wing causes an oscillation of the whole aircraft motion when upset by turbulence or rapid pilot control motion. At higher speeds, the wing oscillation frequency is usually at the resonant frequency of the rigid body motion. Thus, the handling qualities of the aircraft are compromised. Similarly, the same wing oscillation motion is transmitted to the crew station causing adverse ride quality. Further, the large wing motion under turbulence with its increased lifting effectiveness can cause increased wing design loads. Accordingly, by suppressing wing flexure and rigid body/wing bending flutter, the present invention also makes improvements in the related areas of ride quality, handling qualities, and wing design loads.
Thus it is apparent that there has been provided, in accordance with the invention, a stability augmentation system for a forward swept wing aircraft that fully satisfies the objectives, aims, and advantages set forth above. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent in light of foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations that fall within the spirit and scope of the appended claims.
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A stability augmentation system for a forward swept wing aircraft is disclosed that corrects a dynamic instability phenomenon which occurs when the whole vehicle (rigid body) motion couples with the wing structural motion. The sensors are positioned and their output signals combined such that wing structural motion is isolated. Specifically positioned wing control surfaces are operated to suppress such motion with minimal resulting rigid body pitch motion inducing inputs.
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TECHNICAL FIELD
[0001] The present invention concerns a rotor blade for a wind power installation and a wind power installation comprising at least one rotor blade according to the invention.
BACKGROUND OF THE INVENTION
[0002] Rotor blades for wind power installations are generally known and can be seen to a great extent at any wind power installation. Those rotor blades are of an external shape which takes account of the particular aerodynamic demands involved. In order to save on material and weight the rotor blades generally comprise a first internal carrier structure and a surface which encloses that first carrier structure and which is of an aerodynamically favourable configuration.
[0003] In the case of large wind power installations the rotor blades are of considerable dimensions, for aerodynamic reasons. That has an effect on the one hand on manufacture and transportation and on the other hand on the loads which act on the wind power installation in operation. They arise in particular out of the blade surface area which automatically increases with increasing size, and also the increased area swept by the rotor blades.
[0004] Wind power installations have to be designed in accordance with predetermined guidelines for given load situations. They are on the one hand the loads which occur in operation (referred to as operating loads) and on the other hand what are referred to as extreme load situations. Such extreme load situations are derived from given situations or disturbances such as for example a power network failure, a fault in blade adjustment, an extraordinarily strong gust of wind (a once-in-50-years gust etc).
[0005] In that respect it will be appreciated that the loads transmitted to the installation by the rotor blades substantially depend on the rotor blade surface area which is exposed to the wind. For calculating the extreme load, it is assumed that the entire rotor blade surface area is exposed to a maximum wind. All subsequent components such as the drive train, machine carrier, pylon, foundations etc have to be appropriately designed.
[0006] This means that, the smaller the surface area on which the wind acts, that is to say in particular the rotor blade surface area, the correspondingly lower is the load level for which the installation has to be designed. That also signifies a lower level of material expenditure and thus lower costs.
[0007] It will be appreciated however that in conflict with those considerations are a minimum surface area size required for aerodynamic reasons, in order to be able to apply the necessary forces for operation of the wind power installation—for rotating the generator. In that respect, the known rotor blades suffer from the disadvantage that, in particular in the region near the blade root, the rotor blade depth required also increases with an increasing rotor blade size. That rotor blade depth in that case becomes so great that on-road transport of such a rotor blade is already no longer possible or is possible only at incomparably high cost.
SUMMARY OF THE INVENTION
[0008] Therefore one object of the invention is to provide a rotor blade which has the aerodynamically required surface area.
[0009] In accordance with the invention the object is attained by a rotor blade having the features set forth in claim 1 . Various embodiments are described in the further claims.
[0010] The invention is based on the realisation that a given rotor blade area (nominal area) is required in normal operation of the wind power installation while that nominal area is under some circumstances too great in an extreme wind situation and for example in a transport situation.
[0011] In accordance with the invention therefore it is proposed that a rotor blade of the kind set forth in the opening part of this specification is developed in such a way that a part of the surface is actively deformable or movable.
[0012] In a preferred embodiment of the invention a part of the surface is formed from a deformable material which is part of a closed container. That closed container can be filled for example with a gaseous medium, wherein that gaseous medium is acted upon by a predeterminable pressure. That affords a partially inflatable surface for the rotor blade, which can be vented during transportation or when an extreme wind occurs, and thus takes up less space or yields under the pressure of the wind. In that way, the effective surface area of the rotor blade and thus the area for the wind to act thereon are reduced. At the same time the loading on the subsequent components including the pylon is reduced.
[0013] In a particularly preferred embodiment of the invention the rotor blade has a second carrier structure which is movable on itself and/or in itself.
[0014] In that case the deformable material can be fixed to predetermined locations of said second carrier structure. In addition the deformable material can be fixed with one side to a rotatable winding core.
[0015] Now in normal operation of the wind power installation the second carrier structure can be extended, that is to say folding arms can be completely stretched or telescopic arms can be fully extended. The deformable material can be secured with one side to a rotatable winding core. If now the rotor blade area is to be reduced, the winding core is rotated—similarly to an awning or sun blind—in such a way that it winds on the deformable material. At the same time the folding arms are folded and reduce the size of the second carrier structure in the region of the decreasable surface area so that the surface area of the rotor blade is correspondingly reduced.
[0016] In an alternative embodiment of the invention a part of the surface of the rotor blade comprises bar-like or lamellar strips which are respectively arranged on a carrier rail pivotable about its own longitudinal axis. In that arrangement the blades are so oriented in normal operation that they enlarge the aerodynamically operative surface area of the rotor blade. For transportation and/or when extreme loads are involved, the carrier rails can be pivoted in such a way that the blades move for example into the wind shadow of the remaining rotor blade and the surface area of the rotor blade is reduced in that way.
[0017] In a particularly preferred development of the invention a movable part of the aerodynamically operative surface of the rotor blade comprises a single surface element which is displaceable in the direction of the depth of the rotor blade. In normal operation that surface element prolongs the surface of the rotor blade, preferably at the suction side, in order to provide a large, aerodynamically operative surface.
[0018] To reduce the surface area, that surface element can be displaced, comparably to the flap system of an aircraft wing, in such a way that either it is pushed into the rotor blade and is thus covered by the remaining surface of the rotor blade, or it is pushed on to the surface of the rotor blade and in its turn covers the surface of the rotor blade. At any event that provides for a reduction in the surface area of the rotor blade.
[0019] In an alternative embodiment of the invention that surface element can be pivotably mounted at one side to the first carrier structure or the trailing edge of the rotor blade. For the purposes of varying the size of the rotor blade surface area, the element can be pivoted about that pivot axis either towards the suction side or towards the pressure side of the rotor blade.
[0020] In that arrangement, a pivotal movement of the surface element through about 90° provides that the element is disposed substantially perpendicularly to the direction of the air flow at the rotor blade and deploys a corresponding braking effect as it forms an obstacle to the air flowing along the surface of the rotor blade.
BRIEF DESCRIPTION OF THE INVENTION
[0021] A plurality of embodiments according to the invention are described in greater detail hereinafter with reference to the accompanying drawings in which:
[0022] [0022]FIG. 1 shows a plan view of a complete rotor blade according to the invention,
[0023] [0023]FIG. 2 shows a plan view of the front part of a rotor blade according to the invention,
[0024] [0024]FIG. 3 shows a simplified cross-sectional view of a first embodiment of a rotor blade according to the invention,
[0025] [0025]FIG. 4 shows a simplified cross-sectional view of a second embodiment of a rotor blade according to the invention,
[0026] [0026]FIGS. 5 a, 5 b show a simplified cross-sectional view of a third embodiment of a rotor blade according to the invention,
[0027] [0027]FIG. 6 shows a simplified cross-sectional view of a fourth embodiment of a rotor blade according to the invention,
[0028] [0028]FIG. 7 shows a simplified cross-sectional view of-a fifth embodiment of a rotor blade according to the invention,
[0029] [0029]FIGS. 8 a, 8 b are simplified cross-sectional views of a sixth embodiment of a rotor blade according to the invention, and
[0030] [0030]FIG. 9 is a plan view of a structural variant of a rotor blade according to the invention.
[0031] [0031]FIGS. 9 a - 14 show various embodiments of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0032] [0032]FIG. 1 shows in simplified form a plan view of a complete rotor blade according to the invention. The rotor blade 10 is divided into two regions. In this case the rotor blade 10 is of a conventional structure in its essential parts. However, in a region adjacent to the rotor blade root 12 , namely the region of the largest blade depth, it is possible to see that the rotor blade is divided. That division 9 marks the region of the rotor blade 14 whose surface area can be reduced if required and can thus be withdrawn from the action of the wind thereon.
[0033] The fixed part of the rotor blade 10 , the surface area of which remains unchanged, is shown in FIG. 2. As can be clearly seen from FIG. 2 the aerodynamically operative surface of the rotor blade 10 is markedly reduced, and thereby also the loading, particularly in extreme wind situations, is markedly less than in the case of a rotor blade which is constructed in conventional manner.
[0034] [0034]FIG. 3 shows a simplified cross-sectional view of a first embodiment according to the invention. In this case the rotor blade 10 is divided into a front region 11 and a rear box 14 . The rear box 14 comprises two webs of deformable material 18 which together with the rear wall 9 of the front region 11 form a closed container 16 . When now that closed container 16 is filled under pressure with a gaseous medium the deformable material 18 forms a part (identified in FIG. 1 by reference numeral 14 ) of the surface, which is aerodynamically operative in normal operation, of the rotor blade 10 according to the invention.
[0035] A suitable choice of the filling pressure affords such a stability in respect of that part of the rotor blade 10 that it deploys its normal action, under normal wind conditions. In an extreme wind situation however the wind pressure on that part of the rotor blade 10 is greater so that then the external pressure is higher than the internal pressure, and this therefore entails deformation of the rotor blade in the region of the rear box 14 and the rotor blade yields to the external wind pressure. As a result, the surface area on which that extreme wind acts is reduced and thus the loads on the subsequent structural components are reduced. It should additionally be stated that this part of the rear box (in which the filling medium is disposed) can be actively emptied for example when a predetermined wind speed is exceeded, in order to reduce the surface area of the rotor blade. That active emptying has the advantage that the shape of the rotor blade is defined at any time while indefinite situations can occur when the rear box yields as a consequence of the external pressure.
[0036] In order to avoid damage in particular to the container 16 , it is possible to provide for example a pressure relief valve (not shown) through which an increased pressure formed in the container 16 can escape.
[0037] The pressure required for normal operation can be restored by the use of a compressor 17 . If moreover controllable valves and/or pressure sensors (also not shown) are provided, the filling pressure in the container 16 can also be consequentially adjusted in the event of fluctuations in the wind pressure in order always to maintain optimum operating conditions in that way.
[0038] [0038]FIG. 4 shows a second embodiment of the present invention, in which the surface of the suction side of the rotor blade 10 is prolonged, instead of involving a complete rear box 14 . That prolongation is a surface element 24 which adjoins the surface of the front region 11 .
[0039] For the purposes of reducing the aerodynamically operative surface area the surface element 24 can be displaced in the direction of the arrow. That displacement can be effected for example hydraulically, namely with suitable hydraulic cylinders, pneumatically, with pneumatic cylinders, by electrical drives, or in another suitable fashion. It will be appreciated that suitable pumps, compressors or drives (actuators) have to be provided for that purpose, but they are not shown in the Figure for the sake of simplicity.
[0040] In this arrangement such displacement can take place into the front region so that the surface of the front region 11 covers over the surface element 24 . Alternatively the displacement can also take place on the surface of the front region 11 so that the surface element 24 in turn covers over the corresponding part of the surface of the front region 11 . In both cases this involves a reduction in the aerodynamically operative surface of the rotor blade 10 .
[0041] A third embodiment of the present invention is shown in FIGS. 5 a and 5 b. FIG. 5 a shows a winding 20 of a deformable material and reference numeral 30 denotes folding arms which are in the folded condition. The mechanism here can be comparable to that of an awning.
[0042] [0042]FIG. 5 b shows this embodiment in the condition involved in normal operation. The folding arms 30 are extended and, as the deformable material 18 is secured thereto, it was unwound from the coil 20 upon extension of the folding arms 30 so that the winding core 21 now no longer carries the entire winding of material.
[0043] In that unwound situation the deformable material 18 is secured on the one hand to the winding core 21 and on the other hand to the ends of the folding arms 30 , which face towards the right in the Figure. Those ends of the folding arms 30 can in turn be connected by a bar (not shown) in order on the one hand to achieve a higher level of strength for the structure and on the other hand to fix the deformable material there.
[0044] In order to prevent the deformable material 18 from yielding between the winding core 21 and the outer ends of the folding arms 30 it is possible to provide beneath the deformable material a scissor trellis-like device which is actuated synchronously with the folding arms 30 and which supports the deformable material 18 in the extended state.
[0045] A reduction in the operative surface area takes place in the reverse fashion: the folding arms 30 and the scissor trellis arrangement (not shown) are retracted (folded) and at the same time the deformable material 18 is wound on the winding core 21 so that finally the winding core 20 is again in the condition shown in FIG. 5 a and the operative surface area of the rotor blade 10 is reduced.
[0046] In a fourth embodiment of the invention as shown in FIG. 6 the surface element 24 is mounted pivotably at the rear side of the front region 11 and thus prolongs the suction side of that front region 11 . In this case the surface element 24 is supported by a compression spring 28 disposed between the surface element 24 and the carrier structure of the front region 11 .
[0047] In normal operation that compression spring 28 supports the surface element 24 in such a way that it retains the desired position. If now there is a wind pressure on the top side of the rotor blade 10 , beyond the normal operating conditions, the pressure on the surface of the surface element 24 rises and overcomes the force of the spring 28 so that the surface element 24 is pressed downwardly in FIG. 6 and therefore yields to the wind pressure and thus the aerodynamically operative surface area is correspondingly reduced.
[0048] It will be appreciated that, as an alternative to the spring 28 , it is also possible to provide corresponding telescopic elements such as hydraulic or pneumatic devices or mechanical devices for active displacement of the surface element, for example it is possible to use screwthreaded bars and worm drives or the like in order to hold the surface element 24 in a first predetermined position or to move it into a second predetermined position. It will be appreciated that actuation of those control members requires the provision of suitable pumps, compressors or drives which are again not shown in this Figure for the sake of clarity of the drawing.
[0049] Equally it is again possible to detect the wind load which acts on the surface element 24 and the surface element can then be pivoted about the pivot axis in dependence on that detected wind load in order to provide a setting which is the optimum for the instantaneous operating conditions.
[0050] [0050]FIG. 7 shows a fifth embodiment of the invention. In this fifth embodiment, instead of the surface element 24 being pivotably mounted to the rear side of the front region 11 , the surface element 24 is arranged on a pivot spindle 22 which is rotatable about its own longitudinal axis. In the position shown in FIG. 7 the surface element 24 again prolongs the aerodynamically operative surface of the rotor blade 10 .
[0051] Now, to reduce that operative surface, the pivot spindle 22 with the surface element 24 secured thereto is rotated about its longitudinal axis in such a way that the outer end of the surface element 24 moves in one of the two directions indicated by the double-headed arrow. That in turn results in a reduction in the aerodynamically operative surface area of the rotor blade 10 and, concomitantly therewith, a variation in the wind load on the rotor blade 10 and all subsequent components of the wind power installation.
[0052] A variant of the embodiment shown in FIG. 7 is illustrated in FIGS. 8 a and 8 b. In this case the surface element denoted by reference 24 in FIG. 7 is divided in FIG. 8 a into three blade-like or lamellar elements 26 . They are deliberately shown in FIG. 8 a at a spacing in order to clearly show that division. In an actual embodiment, as will be appreciated, those three elements are arranged in such a way that they forth a surface which is as closed as possible and which in turn as smoothly as possible adjoins the front region 11 of the rotor blade 10 .
[0053] Each of the blades 26 is arranged on its own pivot spindle. Each of those pivot spindles 28 is rotatable about its own longitudinal axis and thus permits pivotal movement of the blades 26 by rotation of the pivot spindle 28 about the longitudinal axis.
[0054] [0054]FIG. 8 b shows the apparatus according to the invention in the situation in which the blades are pivoted in such a way that the aerodynamically operative surface of the rotor blade 10 is reduced. In this case the blades 26 are pivoted into the flow shadow of the front region 11 . As a result on the one hand they no longer act as rotor blade surface area, but on the other hand they are also removed from the action of the wind thereon and are thus not exposed to elevated levels of loading thereon.
[0055] Such an arrangement is achieved insofar as, besides rotation of the pivot spindles 28 about their longitudinal axes, the spacing between the pivot spindle 28 which is at the left in the Figure and the front region 11 of the rotor blade 10 on the one hand and between the pivot spindles 28 on the other hand is reduced.
[0056] Insofar as the Figures only show a prolongation of the suction side of the surface, it will be appreciated that alternatively or in addition the surface of the pressure side can be correspondingly altered.
[0057] If a wind power installation is provided with the described rotor blades, it is possible that, when an extreme wind situation occurs, not only is the great wind strength detected, which can be effected by wind speed measuring units, but that the size of the surface area of the rotor blade is then also markedly reduced by suitable control. As shown in FIGS. 1 and 2 for example the area of the rotor blade shown in FIG. 1 is more than 10% larger than the surface area of the rotor blade shown in FIG. 2. While the normal size of the rotor blade is set in nominal operation of the wind power installation, for example at a wind speed in the range of between 2 and 20 m/s wind speed, the size of the surface area can be reduced at a wind speed of above 20 m/s so that the size of the surface area decreases markedly, as shown in FIG. 2.
[0058] The control system is preferably computer-aided and if necessary provides for the respectively optimally set surface area for the rotor blade.
[0059] Further FIGS. 9 a to 14 show further alternative or supplemental embodiments in relation to preceding FIGS. 3 to 8 b.
[0060] [0060]FIG. 14 shows a further structural variant of a rotor blade according to the invention. In this case the structure is built up by pivotable loops 32 which can be covered by a film which is again deformable, and are mounted pivotably at mounting points 34 . By virtue of a movement in the direction of the tip of the rotor blade (indicated by the arrow) those pivotal loops can now be pivoted for example about the mounting points 34 and thus alter the rear box profile.
[0061] [0061]FIG. 11 b (FIG 11 a substantially corresponds to FIG. 6), as a supplemental consideration in relation to FIG. 6, shows an element 25 at the pressure side. As the point of engagement for the spring 28 has not been modified in comparison with the views in FIG. 6 and FIG. 11 a respectively, the elements 24 and 25 must hang together at the trailing edge of the blade so that they are pivotable about a pivot mounting point 26 . Under some circumstances it is appropriate with this structure to provide for overlapping by the rotor blade box 11 over the element 25 along the length of the rotor blade.
[0062] [0062]FIG. 12 b (an enlargement of what is shown in FIG. 7 and FIG. 12 a respectively) also illustrates a pressure-side element 25 which in the illustrated case is fixed by way of a mechanical connection like the suction-side element 24 to a common shaft 12 .
[0063] [0063]FIGS. 13 a and 13 b show a development of what is already illustrated in FIGS. 8 a and 8 b. In this case in part specific shafts 28 are illustrated for corresponding elements on the pressure side. Similarly to FIG. 8 a, FIG. 13 a shows a rotor blade in normal operation. FIG. 13 b shows a situation in which the rear box is no longer operative, by virtue of corresponding rotation or by virtue of displacement of the shafts 28 .
[0064] From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.
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The present invention concerns a rotor blade for a wind power installation and a wind power installation comprising at least one rotor blade according to the invention. The smaller the surface area on which the wind acts, that is to say in particular the rotor blade area, the correspondingly lower is the load level for which the installation has to be designed and the correspondingly more easily can the rotor blade be transported. On the other hand the size of the wind power installation entails minimum dimensions which are unavoidable for operation and below which the installation dimensions may not fall. In order to provide a rotor blade which on the one hand has the aerodynamically required surface area but which on the other hand is so designed that the surface area of the rotor blade and therewith the depth thereof can be reduced in predetermined situations a part of the surface of the rotor blade is deformable or movable.
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RELATED APPLICATION DATA
[0001] This application is a continuation of U.S. patent application Ser. No. 11/223,324, filed Sep. 8, 2005, which claims priority to U.S. Provisional Patent Application No. 60/608,686, filed Sep. 9, 2004, and is a continuation-in-part of International Application No. PCT/IB01/00796, filed Nov. 15, 2001, published in English under publication No. WO 01/85035; and is a continuation-in-part of U.S. patent application Ser. No. 10/192,326, filed Jul. 9, 2002, published under publication No. 2003/0092969, all of which are herein incorporated by this reference.
FIELD OF THE INVENTION
[0002] This invention relates generally to a system and method for moving or for moving and stretching human or animal plastic tissue that exerts a relatively constant tension over a given distance and that is readily adjustable, and more specifically to an anchor for use with such systems.
BACKGROUND
[0003] In general, surgery and surgical treatment involve one or both of tissue separation and tissue joining. In surgery, medical treatment, and medical research, it is desirable to retract tissue, stabilize tissue, and present tissue in a variety of specific orientations to provide access to the area under investigation or repair, ideally in a method that creates minimal trauma beyond what is necessary for exposure and visualization of the operative area. Ultimately, the procedures should allow for immediate, or primary, closure of the wound. Unfortunately, the latter option is not always available in surgical or trauma wound scenarios.
[0004] Moving tissue presents unique challenges, as tissues often resist joining, or closure, depending on the nature of the tissue structure, the circumstances of the tissue separation, and general patient health. Complications related to wound closure and healing generally result from major forces, minor forces and/or compromised healing responses. Major forces are retractive forces created beyond the viscoelastic properties of the tissue, and may be created by: (1) increased internal volume, such as in the case of obesity, which elevates containment forces on the skin system; (2) changes in aspect ratio, such as increased abdominal circumference created in prone, non-ambulatory patients due to muscular atrophy; (3) respiratory muscular activity; (4) muscular response; (5) loss of fascia structure; (6) muscular-skeletal deformation; (7) fleshy appendages; (8) tumors; and (9) severe burns.
[0005] Minor forces are internal forces created by the viscoelastic properties of the tissue, which can cause the skin to retract. Elastic tissues, such as skin, comprised mostly of extracellular matrix (ECM) components along with cells, return to a minimum elastic, or relaxed, state when released from tension. In this relaxed state, tissue tensions are minimized and balanced. Skin tissue in this minimum elastic state will remain relaxed, demonstrating behavior similar to a non-elastic material. The force required to elongate the tissue in this state often approaches a force that will rupture or sheer structural connective elements, causing localized failures or tears. Soft tissue in this minimum elastic state provides minimum surface coverage and has the highest reluctance to stretch. It is known that a gentle but constant force below the sheer force threshold applied to tissue in combination with adequate hydration will, over time, restore certain tissues to near-original or original elastic state. Additionally, this force can be applied to stretch tissue past the point of equilibrium (normal elastic range) to the maximum elastic range and create the thinnest possible configuration, covering the maximum surface area. If tensions in the tissue do not exceed the point at which the connective structural elements are compromised, the tissue remains at the maximum elastic state as healthy tissue, and normal biological processes will allow cell regeneration and associated ECM production to restore normal skin thickness and tension, which is described below as biological creep.
[0006] Plastic tissues, such as skin and muscle, possess certain viscous and elastic rheological properties, and are therefore viscoelastic. Certain plastic tissues are able to increase surface area over time, which can be termed “creep.” “Mechanical creep” is the elongation of skin with a constant load over time beyond intrinsic extensibility, while “biological creep” refers to the generation of new tissue due to a chronic stretching force. A constant and unrelenting force applied to a body tissue, such as skin or muscle, may result in both mechanical and biological creep. Mechanical creep restores the tension originally present but lost in the skin across the incision or wound by retensioning skin, thereby increasing skin coverage. Biological creep occurs more slowly and involves the creation of new tissue. Tissue expansion has long been part of the art of plastic surgery, traditionally accomplished with balloon-type tissue expanders embedded under the skin and externally inflated and increased over time to create expanded pockets of skin for procedures such as breast reconstruction after radical mastectomies, and stretching healthy tissue prior to plastic surgery for the creation of flaps for soft tissue closure.
[0007] Finally, compromised healing responses may complicate wound closure or healing. A surgical or other incision becomes a complicated wound as soon as it falls behind normal healing progression. Wound management, including treatment and care of large skin defects and severely retracted incisions, is an area of increasing importance to the health care community. An aging population and an increase in diseases related to obesity and inactivity have increased the occurrence of complicated wounds and placed an increased burden on health care resources. Factors contributing to compromised wound healing include patient age, weight, nutritional status, dehydration, blood supply to the wound site, immune response, allergies to closure materials, chronic disease, debilitating injuries, localized or systemic infection, diabetes, and the use of immunosuppressive, corticosteroid or antineoplastic drugs, hormones, or radiation therapy. Complicated wounds include, but are not limited to: surgical wounds, diabetic ulcers and other chronic ulcers; venous stastis ulcers; decubitis or pressure sores or ulcers; burns; post traumatic lesions, cutaneous gangrene, crush wounds with ischemic necrosis; wounds having exposed plates or bones; keloids; skin lesions; blunt abdominal trauma with perforations; and other acute, subacute or chronic wounds. Treatment and care of these tissue defects is challenging due to difficulties in closure of open wounds.
[0008] Two common methods of closure of wounds and skin defects include split thickness skin grafting and gradual closure. A split thickness skin graft involves removing a partial layer of skin from a donor site, usually an upper leg or thigh, and leaving a portion of the dermis at the donor site to regenerate and re-epithelialize. In this manner, a viable skin repair patch can be transferred or grafted to cover a wound area. The graft is often meshed, (which involves cutting the skin in a series of rows of offset longitudinal interdigitating cuts) allowing the graft to stretch to cover two or three times greater an area as well as provide wound drainage while healing. Normal biological function of the skin heals the holes after the graft has been accepted. A meshed graft of this type requires a smaller donor area than a conventional non-meshed or full thickness skin graft. However, these methods do not provide optimal cosmesis or quality of skin cover. Other disadvantages of this method include pain at the donor site, creation of an additional disfiguring wound, and complications associated with incomplete “take” of the graft. In addition, skin grafting often requires immobilization of the limb, which increases the likelihood of contractures. The additional operation and prolongation of hospital stay is an additional economic burden.
[0009] Gradual, or progressive, closure is a second method of closure. This technique may involve suturing vessel loops to the wound edge and drawing them together with large sutures in a fashion similar to lacing a shoe. In addition, the wound edges may be progressively approximated with suture or sterile paper tape. The advantages of this gradual, or progressive, technique are numerous: no donor site is required for harvest of a graft, limb mobility is maintained, and superior cosmetic result, more durable skin coverage, better protection from full skin thickness and the maintenance of normal skin sensation may all be achieved.
[0010] Existing devices for effecting a gradual closure have many disadvantages. Current methods and devices draw wound edges together using mechanical devices such as screw-actuated systems that require repeated periodic adjustment because a relatively small skin movement substantially eliminates much of the closure force. Widely used existing closure techniques involve use of relatively inelastic materials, such as sutures or surgical tape. Excessive tension may cut the skin or cause necrosis due to point loading of the tissue. Current solutions include suture bolsters, suture bridges, use of staples as anchors at the wound edge, and the use of ligature wire to distribute the load along the wound margins. These approaches all rely on static ribbon or suture material, which must repeatedly be readjusted in order to function effectively, and even with this constant readjustment, maintenance of near constant tension over time is difficult, if not impossible, to achieve. Widely used traditional gradual closure methods rely on static force through fixed distance reduction, and do not provide continuous or dynamic tension.
[0011] Many current methods of open wound reduction employ static or non-yielding devices such as sutures or hard approximators, which reduce the distance between the wound margins and rely on the skin's natural elasticity to compensate for movement. One problem with these devices has been that when they are at the point of being most effective, when the skin is at the point of maximum stretch, additional skin tension created through motion, such as breathing or walking, creates stress points where the mechanical fasteners meet the wound margins, causing tearing and wound edge necrosis. This has generally required patients to remain immobile during the course of treatment. Existing systems for treating animals need not consider cosmetic result to such a degree as the healthy patient typically masks the wound site with fur, but cosmesis is a critical criteria in the measurement of a successful result from the system in the human application.
[0012] One existing method for effecting closure of a wound utilizes a constant tension, low-grade force to draw wound edges together. One device for practicing this method includes a pair of hooks carried by a pair of sliders that move along a path pulled by a pair of springs. This spring device is enclosed in a plastic housing and is available having various curvatures. The sharp hooks used in this system may damage the skin. The constant force used is a dictated force that is not variable. Other closure devices use elastomeric material, including rubber bands and other types of compressive and non-compressive materials, to approximate wound margins. One kit requires bonding to the skin with an adhesive and also requires periodic adjustment to tighten the straps. Other known closure devices use hooks and elastic loops, which must be replaced with smaller elastic loops to maintain tension, or a motor power source to provide a tightening means. Finally, another current device consists of two surgical needles, two U-shaped lexan polycarbonate arms with hooks on the bottom surface, a threaded tension bar and a polycarbonate ruler. The needles are threaded along the wound margin and each arm is positioned above a needle, with the hooks piercing the skin and engaging the needles. The tension bar is then locked, and tension can be adjusted using the screw.
[0013] Existing methods of gradual wound closure fail to provide an effective gradual closure that restores original skin tensions lost across the wound. For example, one system has a single tension of 460 grams. In many instances, such as with the elderly or with compromised skin, this force is too great, resulting in localized failures, tears and necrosis. Many current devices are cumbersome, restrict patient mobility, must be completely removed for wound dressing and cleaning, and are usable in a relatively limited number of situations because of size constraints. Many also require a surgeon for reinstallation after removal for wound dressing. Finally, many current devices cannot readily be used for radial closure of wounds due to their limited ability to pull in a single direction along an overhead beam, thereby restricting their application to parallel pulls along the same axis.
SUMMARY OF THE INVENTION
[0014] This invention provides manipulation and control of tissue positions and tensions on a living person or animal, utilizing both tissue stretch and creep to restore and move tissues. This invention provides methods and devices for moving or for moving and stretching tissue that are simple, easy to use, cost-effective, extremely versatile, self-adjusting and capable of exerting relatively constant force or tension over a variety of distances and at various intersecting angles in wounds having simple or complex geometry.
[0015] Components of this invention exert a dynamic force on the tissue, providing and maintaining a maximum safe counter-traction pressure or force across a wound margin or other area. Systems of this invention create controlled constant and unrelenting tension, which can be applied to counteract major or minor retraction forces or to achieve maximum mechanical and biological yields to move or to move and stretch plastic tissue, including closure of large retracted skin defects.
[0016] Terms used herein are generally defined and, in some cases, abbreviated, as they are introduced. For convenience, selected terms are also defined here. A force applying component (“fac”) generally stores energy in a manner that exerts force and transmits the force. An elastic force applying component (“efac”) combines these two functions in a single elastic component. The tissue manipulation system of this invention utilizes facs coupled to force coupling components (“anchors”) that couple to tissue the force exerted by the force applying component. The term “elastomer” refers to relatively elastic material, such as silicone, or latex rubber. The term “non-reactive” is used to describe components that are either immunologically inert or hypoallergenic.
[0017] Coupling a fac to tissue can occur simply by passing a fac or a portion of a fac such as a suture through a hole created to penetrate tissue. However, such rudimentary coupling works poorly for several reasons, importantly including the extremely poor force distribution across the tissue and the absence of any practical means for adjusting the force exerted by the suture over a period of time.
[0018] Anchors of this invention include structures for coupling to force applying components that permit quick, easy attachment and reattachment of various facs, particularly including facs made of silicone, which is extremely difficult to secure. Anchors of this invention provide distribution of force applied and bolster tissue proximate holes through which an fac passes.
[0019] This invention provides advances over current methods for moving or moving and stretching plastic tissue through the introduction of gradual but unrelenting tension that is readily adjustable. When tension adjustment is required, it can be accomplished quickly, and the force applying components can include an easily read quantitative visual indicator. Utilizing dynamic force to move and stretch tissue offers the advantage of a relentless countertraction force, while allowing for expansion and contraction of the wound site, which greatly enhances patient mobility and is compliant with respiratory movements.
[0020] This invention can be used to apply dynamic force for closure or remodeling of tissue to close dermal wounds, incisions, or defects that may be associated with a variety of conditions, as well as in the stretching of healthy skin in preparation for a skin graft, flap or other remodeling procedure. In one example, this invention includes a system of button anchor assemblies for moving or for moving and stretching plastic tissue, particularly including deep fascia and muscle layers of the abdominal or thoracic cavity wall, in surgical, post surgical, and post traumatic reconstruction where the wound margins are beyond a distance that permits normal re-approximation.
[0021] Prior patent applications assigned to Canica Design Inc. describe in detail the use of elastomers and anchors to move and stretch tissue. While the structures disclosed are highly effective, this invention extends the principles disclosed in the earlier patent applications to additionally provide different anchors for the re-approximation of severely retracted abdominal wall and full thickness thoracic wounds where a closure force is required to be applied to the sub-dermal layers. Systems of this invention allow for such a force to be applied and externally controlled during treatment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a perspective view of a system of this invention for moving tissue.
[0023] FIG. 2 is a perspective view of a button anchor and anchor tail of the system of FIG. 1 .
[0024] FIG. 3 is a top view of the button anchor of FIG. 2 .
[0025] FIG. 4 is a front view of the button anchor of FIG. 2 .
[0026] FIG. 5 is a top view of the anchoring portion of the button anchor of FIG. 2 .
[0027] FIG. 6 is a top view of the anchor pad of the button anchor of FIG. 2 .
[0028] FIG. 7 is a perspective view of the anchor pad of the button anchor of FIG. 2 .
[0029] FIG. 8 is a top view of the anchor tail of the button anchor of FIG. 2 .
[0030] FIG. 9 is an enlarged detail perspective view of a portion of the anchoring portion of the button anchor of FIG. 2 showing the anchor tail locking interface.
[0031] FIG. 10 is a perspective view of installation of part of the system of FIG. 1 .
DETAILED DESCRIPTION
[0032] Anchors of this invention are used to transmit and distribute force to the tissue to be moved or stretched. A force applying component according to this invention may be formed in rods, cords, bands, loops, sheets, nets, wires, strands, cables, tubes or other suitable structure. In one embodiment, the fac is an elastic strand that flattens out at the point of maximum load and becomes load dissipating. In one embodiment, a rod-shaped fac is driven through the tissue using a cannula-like device and is attached at each end to an anchor.
[0033] Force applying components (“facs”) of this invention may have elastic properties “efacs”) and may be made from any suitable elastomeric material, including, without limitation, latex rubber, silicone, natural rubber and materials of similar elasticity, GR-S, neoprene, nitrile-butyl-polysulfide, ethylene-polyurethane, polyurethane, or any other suitable material that exhibits the property of exerting a return force when held in an elongated state at tensions and distances that are useful in the context of this invention. Efacs may provide a dynamic opposing force equal to or greater than the naturally occurring elastomeric traction forces of the tissue. The efacs of this invention generally are not endless loops but rather are lengths of a single strand, sometimes called a “monostrand,” and may be either solid or hollow. In some instances, multiple strands or endless loops or bands may be used. Significantly, the efacs used in practicing this invention may be secured to a tissue attachment structure at virtually any point along the efac, providing variable tension within the elastic limits of the elastomer used. Use of a non-reactive fac is generally desirable. Non-reactive facs include components that are either immunologically inert or hypoallergenic, such a elastomers formed from silicone or a hypoallergenic form of latex rubber.
[0034] Elastomers having various durometers may be used for the force applying components of this invention. Although other elastomeric materials and sizes of material may be used, polyurethane, thermoplastic (TPE) or rubber elastomer in monofilaments 1 mm-8 mm in diameter have been found to be useful in practicing this invention.
[0035] In one embodiment, an efac has a 0.125 inch diameter with a nominal durometer of 40. Other efacs, such as efacs having a smaller diameter, may also be provided and differentiated one from another based on color. Alternative shapes, sizes and strengths may be appropriate in some situations. An extruded silicone efac may have a durometer of 40 (which allows a 5:1 stretch ratio). A molded silicone efac may have a durometer of 5 (which allows a 12:1 stretch ratio). In one example, a secure mechanical lock may be achieved by restraining the efac within a constricting aperture of a size greater than the tensioned diameter but less than the untensioned diameter, such that the untensioned end of the elastomer acts as a restraint upon the aperture.
[0036] Force applying components can include marks indicating tension or stretch. The indicia may be formed from colorant, including any means for providing visual contrast, such as ink, dye, paint, or the like. Force applying components may also be disposable.
[0037] As noted above, it is generally desirable to use a non-reactive elastomeric force applying component such as a silicone, but silicone is normally difficult to secure. The viscoplastic properties of low durometer material, such as silicone, fall below the threshold where the material will hold a knot. Adequate constricting force may not be applied upon the material by the material itself to retain it under load because the application of the load reduces the material diameter beyond the minimum compression diameter of the constricting loop. This precludes the use of conventional surgical knot tying techniques because such knots will not hold. An additional complication is the tendency of the material to creep, or slip, when alternative capture methods are used. Thus, it is difficult to secure a silicone efac when a force is applied to the efac without the efac being cut or otherwise caused to fail by the securing structure.
[0038] Successful structures for securing a silicone elastomer (or other low durometer material) must clamp the silicone elastomer structure with enough force to hold it in place (avoiding creep) but with sufficiently distributed force that the elastomer is not severed. This invention provides structures that result in sufficient contact between an efac (including a silicone efac) and anchor structure that the two do not slide relative to each other while avoiding cutting or tearing the efac. Such structure can be provided by squeezing the efac between, or forcing it against, planar or relatively large radius arcuate surfaces while avoiding contact between the efac and arrises (intersections of planar surfaces) that might cut the elastomer.
[0039] Such a structure can be achieved with opposed planar or arcuate surfaces forming a Vee-shape and oriented so that tension on the efac forced into the gap between the surfaces will cause any reduction in outer diameter of the efac, such as occurs with added load, to result in the efac securing purchase lower in the Vee. In this manner, the efac-to-anchor structure contact is maintained, thereby improving the lock between the elastomer and anchor structure. Similarly, parallel surfaces may be engineered to provide an entrapment force and prescribed release tension for the efac in order to provide a maximum applicable tension and integral safety release.
[0040] The opposed surfaces can be provided by a variety of structures, such as arcuate surfaces provided by suitably rigid round wire or rod or by rounded opposed edges of plates of metal, plastic or other suitable material. Such structure can also be provided in other forms. For instance, the opposed surfaces between which the efac is trapped can also be provided by opposed flanges, typically positioned on a post or column and shaped so that the opposed flange surfaces get progressively closer together at points nearer the column. In such a structure, a first one of the opposed surfaces can be planar and can be, for instance, a flat base, provided that the other flange or other efac contact structure provides a surface that gets progressively closer to the first surface as the efac moves in the direction force applied to it during use will cause it to tend to move. For instance, the other flange can present a truncated conical surface.
[0041] As shown in FIGS. 1-3 , a button anchor 8 of this invention comprises an anchoring portion 10 , which rests on an anchor pad 12 and which can optionally engage a load distributing anchor tail 14 . This button anchor 8 remains external to the human or animal tissues, and comprises specific features for anchoring a fac traveling across a wound or through tissues that, by its presence and ability to apply a reducing force, provides the specific benefit of moving or moving and stretching tissue to bring reduction or closure of a full thickness wound where the wound margins lie beyond a distance where they can be primarily closed without undue force. In one example, a fac is passed through the skin, engaging or encircling the sub-dermal structures requiring closure, and returned through the skin on the other side of a wound or incision. The button anchors 8 are applied to the ends of the fac, allowing the fac to be tensioned and anchored, thereby applying a sub-dermal reduction force, as illustrated in FIG. 1 . In an alternative embodiment, button anchors 8 positioned on opposite sides of a wound secure a fac that passes over the wound and that does not penetrate the tissue.
[0042] As shown in FIGS. 2-5 , the anchoring portion 10 has a large slot 16 and a smaller slot 18 for engagement of an efac, such as an elastomer. Slot 18 includes walls 36 and is a metered tension, elastomer-locking slot, with a shape, length and size such that the slot 18 captures and anchors the elastomer but allows the elastomer to migrate if tension exceeds a pre-determined level, thereby creating a limit to the amount of force that can be applied by the system. This limit is determined at the time of manufacture of the anchoring portion 10 by controlling the relationship between the size of the slot 18 and the diameter or cross-sectional area of the elastomer. The cross-sectional area of the untensioned portion of the elastomer decreases as the elastomer elongates under increased tension. If a force applied to the elastomer exceeds the therapeutic force range, elongation and resulting reduction in diameter cause the elastomer to release within the slot, returning the quantity of tension to one within the therapeutic limit of the elastomer.
[0043] Convex upstanding regions 38 (visible in FIGS. 1 and 4 ) of the anchoring portion 10 prevent other objects from catching the edges of the button anchor 8 .
[0044] The anchoring portion 10 may be molded of polycarbonate plastic or any other appropriately rigid and strong polymeric material suitable for use in the surgical applications for which the present invention is intended. Alternatively it may be molded, machined or otherwise formed or fabricated of any other suitably strong, surgically acceptable material such as stainless steel.
[0045] While the size of the button anchor 8 of this invention may be varied depending on the situation in which it is used, anchoring portion 10 may be approximately 32 mm in diameter. An anchoring portion 10 for use with an elastomeric three mm diameter, 40 durometer silicone cord may have a slot 18 one mm in width (i.e., the distance between walls 36 ), 7.3 mm in height and 11 mm in length. Many other dimensions are also usable provided that the desired coupling with elastomer is achieved (generally as described above).
[0046] Various arcuate or curved surface shapes for anchor efacs attachment structures are described above. It should be understood that functionally equivalent shapes can also be used, such as, for instance, a rod having a cross-section that is not curved but rather is a polygon.
[0047] As shown in FIGS. 6 and 7 , anchor pad 12 includes a slot 15 that corresponds to slot 16 of the anchoring portion 10 . Anchor pad 12 dissipates the compression load exerted by one or more facs connected to the anchoring portion 10 over the surface of the patient's skin and works to prevent maceration or undue restriction of the underlying blood circulation. The anchor pad 12 is generally the same size and shape as the anchoring portion 10 , but it may be smaller or larger in alternative embodiments. For example, larger pads may be used in patients with compromised skin tissues, including the elderly or those with associated co-morbidities, such as diabetes.
[0048] The anchor pad 12 may be made of a compressible material such as silicone, or any other suitable material. The skin contact surface (i.e., the underside) of anchor pad 12 may be smooth or it may be textured in order to accommodate fluid dissipation. The skin contact surface may be flat, convex, concave or multi-planar to accommodate anatomical contour. The skin-contacting surface of pad 12 may also be coated or treated to provide antimicrobial properties. In one embodiment, the skin-contacting surface of the anchor pad includes an adhesive.
[0049] As shown in FIG. 5 , the anchoring portion 10 is penetrated by apertures 20 that secure the anchoring portion 10 to the anchor pad 12 . Tabs 13 (shown in FIG. 7 ) project from anchor pad 12 and are received in apertures 20 of anchoring portion 10 . Enlarged diameter end 17 of tabs 13 retain anchoring portion 10 on pad 12 . In an alternative embodiment, the anchor pad 12 is adhered, adhesively bonded, or molded to anchoring portion 10 . In one example, the anchor pad 12 and anchoring portion 10 are an integral unit.
[0050] As shown in FIGS. 2 and 5 , finger grips 22 facilitate gripping and manipulating the button anchor 8 by opposed digits. Finger grips 22 are concave in the embodiment illustrated in the drawings, but the gripping portion may also be convex, multi-planar or textured.
[0051] Optional anchor tail 14 , shown in FIGS. 2 , 3 and 8 , may be utilized to further dissipate and distribute the shear-load placed on the skin by performing wound closure over the maximum possible surface area. In one embodiment, the anchor tail 14 is formed from polyurethane foam having an adhesive for attachment to the skin and includes a wire that forms a loop 28 at end 26 . In alternative embodiments, the anchor tail 14 may be formed from any suitable fabric, foam or film. Such material may be elastic or inelastic. Preferably the anchor tail 14 material conforms to the skin surface and mimics the elasticity of the skin. In addition, the loop 28 may be formed or molded as a separate or integral component.
[0052] Anchoring portion 10 of button anchor 8 includes structure for engaging anchor tail 14 . Such structure may include a hole, tab, cleat or other suitable structure. In one embodiment, shown in the Figures, and particularly in FIG. 9 , the anchoring portion 10 includes a hook 30 having a ramp 32 for guiding the wire loop 28 of tail 14 up and into depression 34 of anchoring portion 10 . In use, the anchor tail 14 is attached to the anchoring portion 10 via the engagement hook 30 and is adhered to the skin. In this manner, anchor tail 14 bolsters the button anchor 8 and dissipates the forward force load (a force vector that travels toward the wound edge and parallel to the skin surface) over a large area of healthy skin located behind the button anchor 8 . While the hook 30 and loop 28 provide one example of structure to couple the anchor tail and anchor, any suitable structure may be used.
[0053] The system of this invention may be used to provide deep fascia repair and deep fascia dynamic wound reduction. In one embodiment, illustrated in FIG. 10 , a silicone elastomer 13 is coupled to a cannula-like device 42 and is passed through the dermis 44 , fat layer 46 , and fascia 48 at an optional anchor placement mark 50 placed on the skin prior to installation of the system. After passing through the area of the wound 7 , the elastomer 13 is presented through slot 16 of anchoring portion 10 and slot 15 of anchor pad 12 of button anchor 8 , where it is then captured and secured in smaller slot 18 of anchoring portion 10 . In this manner, closure force is applied to a wound or incision 7 . Multiple sets of anchors and elastomers may be used, as shown in FIG. 1 .
[0054] The elastomer 13 may either be presented through the skin and through the slot 16 of an anchor previously placed, or the elastomer 13 may exit the skin, at which time the slot 16 and the pad slot 15 of the anchor 8 may be moved into place around the elastomer 13 . The efac may be used to apply tension to sub-dermal structures (deep fascia) but the efac tension may be adjusted from above the skin by increasing or decreasing the tension at the smaller slot 18 . The anchor 8 acts as a grommet, removes the point load from the exit hole to reduce the occurrence of localized failures, and also allows adjustment of the tension across the wound. In this manner, the anchor bolsters the perimeter of the transcutaneous opening through which the elastomer passes, reducing localized failures and also reducing scarring.
[0055] A system according to this invention may provide wound stabilization of abdominal procedures. For example, this system may be used to restore radial abdominal integrity during prolonged interventions for complications such as abdominal infections management or which require large abdominal access. This system increases patient comfort and mobility by providing abdominal containment and support, and maintains normal skin tensions during intervention to minimize retraction.
[0056] Another system of this invention may provide stability to sternal or chest non unions as can arise after open heart surgical procedures. In addition, systems of this invention may be used with conventional primary wound closure methods to distribute skin system tensions to healthy skin beyond the wound, thereby minimizing stress at the wound site and reducing dehiscence. A system of this invention may be applied pre-operatively to tension skin and create surplus tissue, allowing excisions to be covered and closed in a conventional manner. Embodiments of this invention may also be used as a dressing retention system by providing efac lacing across the wound site, which passes over the wound dressing and secures it in position. Adhesives may be used on the skin contacting surface of the anchor pad but such adhesives normally would not be required, thereby further facilitating the periodic inspection and cleaning of tissues under the anchor pads.
[0057] All of the tissue attachment structure and anchor designs described herein may be produced in a variety of sizes.
[0058] The systems and methods of moving or moving and stretching plastic tissue according to this invention are not confined to the embodiments described herein but include variations and modifications within the scope and spirit of the foregoing description and the accompanying drawings. For instance, the scale of the components of the invention can vary quite substantially depending on the nature and location of the tissue with which the invention is used. The configuration of the tissue attachment structures can also be varied for the same reasons and for aesthetic reasons. While most of the elements of the illustrative embodiments of the anchors of this invention depicted in the drawings are functional, aspects of the shape and appearance of the illustrative embodiments are nonfunctional and ornamental.
[0059] The materials from which the components used in practicing this invention are made can be those described above as well as others, including materials not yet developed that have appropriate properties of strength, elasticity and the like that will be apparent to those skilled in the art in light of the foregoing. For instance, useful materials generally must be sterile or sterilizable and non-reactive. The illustrated components are typically intended to be disposable, but the invention can also be practiced using reusable components.
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A system of non-reactive components for moving or for moving and stretching plastic tissue that exerts a relatively constant dynamic force over a variety of distances and geometries, that is easily adjustable, and is self-adjusting. This system includes a “button anchor system” for moving tissue, particularly including deep fascia and muscle layers of the abdominal or thoracic cavity wall, in surgical, post surgical, and post traumatic reconstruction where the wound margins are beyond a distance that permits normal re-approximation. Button anchor assemblies allow re-approximation of severely retracted abdominal wall and full thickness thoracic wounds where a closure force is required to be applied to the sub-dermal layers. Systems of this invention allow for such a force to be applied and externally controlled during treatment.
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RELATION TO PREDECESSOR PROVISIONAL PATENT APPLICATIONS
[0001] The present patent application is descended from, and claims benefit of priority of, U.S. provisional patent applications serial Nos. 60/216,937 filed on Jul. 10, 2000, for NANOPARTICULATE TITANIUM DIOXIDE COATINGS AND PROCESS FOR THE PRODUCTION THEREOF AND USE THEREOF; 60/202,033 filed on May 5, 2000 for ANTIFOULING PHOTOACTIVE AGGREGATES; 60/188,761 filed on Mar. 13, 2000, for PHOTOACTIVE ANTIFOULANT AGGREGATES; and 60/170,509 filed on Dec. 13, 1999, for PREPARATION OF COMPOSITE PHOTOCATALYTIC PARTICLES. All predecessor provisional patent applications are to the selfsame inventor as the present patent application.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention generally concerns photocatalytic particles and aggregates and coatings, especially as may incorporate nanoparticulate titanium dioxide, and to processes for the production and the use thereof.
[0004] The present invention further generally concerns photocatalytic materials as are effective for, inter alia, killing microorganisms, including algae and bacteria, on contact in the presence of light in the visible or ultraviolet wavelengths. More particularly as regards these photocatalytic materials, the present invention concerns (1) composite photocatalytic materials in the form of particles and other bodies with surfaces which particles and bodies have (1a) cores nondeleterious to photocatalytic action coupled with (1b) photocatalytic surfaces; and (2) liquids, aggregates and solids incorporating such (1) photocatalytic materials.
[0005] 2. Description of the Prior Art
[0006] 2.1 Photocatalytic Coatings, Especially as May Incorporate Nanoparticulate Titanium Dioxide
[0007] A first aspect of the present invention will be seen to concern the production, and use, of photocatalytic coatings, especially as may incorporate nanoparticulate titanium dioxide.
[0008] For the purposes of the present invention, nanoparticulate titanium dioxide coating (“nano-coating”) is taken to be surface coatings of rutiles, anatases and amorphous titanium dioxide having a particle size of 1 to 100 nm, preferably of 1 to 50 nm, and more preferably of 1 to 10 nm, or titanium dioxide having the above-stated particle size dispersed and adhering on a surface.
[0009] 2.1.1 Applications for Titanium Dioxide Nano-coatings
[0010] Applications for such titanium dioxide nano-coatings include the following. Pigmentary particles may be coated with titanium dioxide to impart improved U.V. absorption or opalescent effects. In this application the light transparency of the titanium dioxide due to the small particle size is a particularly desirable characteristic of the nano-coating.
[0011] Titanium dioxide nano-coatings may be applied to building materials as a photocatalytic coating providing anti-fouling benefits. Photocatalytic surfaces so created are particularly useful in public areas such as rest rooms and hospitals to reduce bacterial contamination.
[0012] A titanium dioxide nano-coating may be applied as a photocatalytic coating to a waste water treatment apparatus.
[0013] A titanium dioxide nano-coating may be applied to both powders and continuous surfaces as a coating for absorption of U.V. radiation,
[0014] A titanium dioxide nano-coating may be applied to a surface as a flame retardant surface.
[0015] A titanium dioxide nano-coating may be applied to a surface as a support layer in a dye solar cell.
[0016] The use of titanium dioxide nano-coatings is, however, currently still restricted by the fact no economic process is known which is capable of producing nano-coatings comprised of the stated particle size on an industrial scale. The present invention deals with this issue.
[0017] 2.1.2 Sol/gel Coatings of Nano-particulate TiO 2
[0018] The most important previous methods for the formulation of nano-particulate TiO 2 coatings—also known as titanium dioxide nano-coatings—may be grouped together under the superordinate term of “sol/gel coatings”. Sol/gel coatings have been described in many journal articles and patents. Nano-particles of TiO 2 in the sol/gel form are attracted to surfaces by van der Waals' forces and may be further anchored to surfaces by stronger chemical bonds such as fusion bonds.
[0019] Sol/gel materials are desirable because, when applied as a film to surfaces, these nano-particulate suspensions create the thinnest surface coatings, disperse evenly, and have good adhesion properties.
[0020] As discussed in U.S. Pat. No. 5,840,111, the sol/gel coatings are generally formulated using the alkoxide method, i.e. the carefully controlled, frequently base- or acid-catalyzed hydrolysis of metal alkoxides and similar molecular precursors in mixtures of water and one or more organic solvents. The solvent used is generally the same alcohol as is the basis of the alkoxide. One disadvantage of this previous process is that costly educts and complicated processing are required. Moreover, the products have an undesirably elevated carbon content.
[0021] Originally developed for silicon compounds, the alkoxide method is increasingly also being used for the synthesis of nano-titanium dioxide in accordance with the equation
Ti(OR) 4 +2H 2 O→TiO 2 +4 ROH
[0022] See, for example, J. Livage, Mat. Sci. Forum 152-153 (1994), 43-54; J. L. Look and C. F. Zukoski, J. Am. Ceram. Soc . 75 (1992), 1587-1595; WO 93/05875.
[0023] It is frequently possible to produce monodisperse particles, i.e. particles having a very narrow particle size distribution, by appropriate selection of the reaction conditions, permitting production of homogeneous particles ranging in diameter from some micrometers down to a few nanometers. One example of such a special processing method is working in microemulsions, by which means it is possible to limit particle size. See, for example, D. Papoutsi et al., Langmuir 10 (1994), 1684-1689.
[0024] The educts for virtually all sol/gel reactions for the production of TiO 2 nano-coatings, whether by conventional or microemulsion methods, are titanium alkoxides (Ti(OR) 4 ), the alkyl residues R of which conventionally contain 2 to 4 carbon atoms. However, due to the high price of these alkoxides and particular handling requirements (protective gas, strict exclusion of moisture in order to prevent premature hydrolysis), the stated reactions have not been considered for a large scale industrial process.
[0025] Still furthermore, working in microemulsions has the disadvantage that, due to the frequently low concentration of the reactants, (i) the space/time yield is low and (ii) large quantities of water/solvent/surfactant mixtures are produced which must be disposed of.
[0026] An alternative, a non-hydrolytic sol/gel manufacturing process has recently been proposed which involves reacting metal halides with oxygen donors such as ethers or alkoxides. See S. Acosta et al., Better Ceramics through Chemistry VI (1994), 43-54.
[0027] 2.1.3 Chemical Vapor Reaction Processes for the Production of TiO 2 as May be Used in Nano-Coatings
[0028] Yet another group of methods for the production of ultra-fine titanium dioxide particles comprises the so-called CVR (chemical vapor reaction) processes, which are based upon the reaction of vaporizable metal compounds (generally alkoxides) with oxygen (air) or steam in the gas phase. This process is described, for example, in U.S. Pat. No. 4,842,832 and Europe patent no. EP-A 214 308. While small quantities of powders produced using such processes are presently (circa 2000) commercially available, they are extremely expensive.
[0029] 2.1.4 Industrial Processes Producing TiO 2 Undesirably Coarse for Use in Nano-Coatings
[0030] Of the hitherto known processes performed on a large industrial scale for the production of finely divided (sub-pigmentary) titanium dioxide, none yields a product comparable in terms of fineness and transparency with sol/gel materials. These industrial processes include hydrolysis of TiCl 4 as is shown in Great Britain patent no. GB-A 2 205 288; production of rutile nuclei in the sulfate process as is shown in Europe patents nos. EP-A 444 798 and EP-A 499 863; and peptisation with monobasic acids of titanium dioxide hydrate which has been washed free of sulfate as is shown in Europe patent no. EP-A 261 560 and also in U.S. Pat. No. 2,448,683.
[0031] It is also known from U.S. Pat. No. 5,840,111 to react a solution comprising sulfuric-acid and titanyl sulfate by adding an alkaline-reacting liquid such that the alkaline liquid is present in a stoichiometric deficit relative to the “free sulfuric acid” (which is the total sulfur content minus that proportion bound in the form of foreign metal sulfates). The resultant solution is then flocculated by adding a monobasic acid. This process is inefficient because a significant portion, approximately 50%, of the titanyl sulfate does not react acidically with the stoichiometrically deficient alkaline liquid so that a significant portion, approximately 50%, of the potential TiO 2 product is left in solution in the form of titanyl sulfate.
[0032] It is also known from the literature to hydrolyse TiCl 4 under hydrothermal conditions, wherein depending upon the reaction conditions (concentration, temperature, pH value, mineralisers), nano-anatases and nano-rutiles are obtained. See H. Cheng et al., Chem. Mater. 7 (1995), 663-671. However, due to the complicated processing requirements, it is doubtful that a commercially viable product may be obtained using this method.
[0033] 2.1.5 Objects of the Present Invention as Regards the Production and Use of Coatings, Particularly Nanoparticulate Titanium Dioxide Coatings
[0034] It is thus a primary object of the invention to produce at high yield a well-adhering thin, uniform, transparent titanium dioxide nano-coating—in which nano-coating is present titania nanoparticles—and to provide a process for the application thereof. The processes for each of (1) the production and (2) the application of nano-titanium dioxide coatings should be economically viable, and would preferably entail only relatively simple and foolproof conventional processing requirements that, when conducted at an industrial large scale, will reliably produce a titanium dioxide nano-coating product fully having the most favorable thinness, uniformity, and adhesion properties of the best sol/gel films.
[0035] 2.2 Prior Art Regarding the Application of Photocatalytic Coatings
[0036] The previous sections 2.1 have discussed prior art, and the deficiencies of the prior art, in the economical industrial scale production of photocatalytic coatings particularly including titanium dioxide nano-coating. As might be expected, the present invention will teach a solution to this production problem.
[0037] However, the present invention extends further, it having been recognized that photocatalytic coatings—howsoever inexpensively obtained—may be beneficially applied in a manner distinguished over the prior art.
[0038] The prior art for the application of photocatalytic coatings of any type basically shows a substantially even, uniform and homogeneous application of these coatings, mostly in the form of solutions that are applied to surfaces in the manner of paint. The present invention will soon be seen to teach otherwise, and to teach that photocatalytic materials are usefully unevenly applied so as to create “hot spots” of photocatalytic activity, even if and when the “hot spots” are quite small, having dimensions on the order of molecules, and occasionally widely dispersed.
[0039] 2.2 Prior Art Regarding the Direct Incorporation of Photocatalytic Materials In Other Materials for Anti-fouling Purposes
[0040] Photocatalytic titanium oxides have been the focus of several efforts to introduce antifouling properties to coatings and masonry. Examples include Japanese Patent 11 228 204 “Cement composition containing photocatalyst and construction method using it”; Japanese Patent 11 061 042 “Highly hydrophilic inorganic coatings, coated products therefrom and their uses”; and European Patent EP-A885 857 “Use of a mixture of organic additives for the preparation of cementitious compositions with constant color, and dry premixes and cementitious compositions containing the mixture”. Wide-spread commercial use has been limited largely due to the relatively high cost and poor dispersion characteristics of commercially available photocatalytic titanium oxide powders. Using photocatalytic titanium oxide is attractive for an antifouling product because titanium oxides exhibit robust weatherability and low toxicity. The anatase crystalline form of titanium dioxide exhibits high photocatalytic activity and has been the most widely explored. A problem has been to introduce enough anatase titanium dioxide into the coating or surface formulation to impart anti-fouling properties while maintaining an economic advantage over commercially available leaching-type biocides.
[0041] While prior art techniques attempt to minimize cost barriers, they are deficient in one or more areas. For example, extenders have been added to paint formulations to space photocatalyst particles to preserve photocatalytic efficiency, however, these extenders are difficult to distribute within the paint matrix to maximize photocatalytic efficiency. Extenders are typically larger particles and/or in the form of aggregates and thus tend to increase the effective photocatalyst volume concentration and decrease photoactive efficiency as they are added to replace paint resin content, a phenomena analogous to decreasing scattering efficiency as described in F. Stieg, “The Effect of Extenders on the Hiding Power of Titanium Pigments”, Official Digest, 1959, pp. 52-64.
[0042] Titanium oxide particles, especially anatase titanium dioxide, are difficult to distribute evenly in coating formulations. Anatase titanium dioxide preferentially agglomerates due to a relatively large Hamaker constant (6×10 −20 J) that causes individual photocatalyzing particles to clump and effectively shade each other, reducing photocatalytic efficiency. It would be desirable for photocatalytic particles to disperse more easily in slurries and coating formulations.
[0043] A common strategy for improving the dispersion of pigmentary titanium dioxide is to prepare a composite pigment. U.S. Pat. No., 5,755,870 to Ravishankar provides a review of such strategies the teachings of which are incorporated herein by reference. However, the composite pigments described do not attempt to maximize photocatalytic activity and indeed often subdue photocatalysis as a way to. protect paint resin from photodegradation.
[0044] There is a need for a commercially viable photoactive antifoulant composition that exhibits high photocatalytic activity and disperses easily in slurries and coating formulations.
SUMMARY OF THE INVENTION
[0045] The present invention contemplates the (i) production and (ii) application, including at industrial scale, of nanoparticulate titanium dioxide (TiO 2 ), and a sol, suitably used as a coating, made of such nanoparticulate TiO 2 .
[0046] The present invention further contemplates composite photocatalytic materials. The preferred materials consist of (1) bodies, most preferably in the form of carrier particles, made of material that is non-photocatalytic and non-interfering with photocatalytically-induced reactions. These (1) bodies have (2) surfaces that are photocatalytic, ergo composite photocatalytic materials.
[0047] The present invention still further contemplates highly photocatalytic aggregate particles comprised of an extender particle with discrete photocatalytic titanium oxide particles exposed on the surface. The aggregates may be used as additives for making non-toxic, antifouling coatings and building materials. This invention also includes building materials containing these aggregates and processes for making the aggregates and slurries of the aggregates.
[0048] 1. Production and Application of Nanoparticulate Titanium Dioxide (TiO 2 ) Coating
[0049] In its aspect concerning the production of nanoparticulate titanium dioxide (TiO 2 ), and the use of such TiO 2 in a sol and as a coating, the preferred particle size distribution of the nanoparticulate titanium dioxide (TiO 2 ) is between 1 nm to 100 nm (as determined from scanning electron microscopy) with less than 0.1 wt. % of carbon in the form of organic compounds or residues. Prior to application, the nanoparticulate TiO 2 coating has a particle size distribution of between 1 nm to 100 nm as determined from the absorption onset, a quantum size effect measurement as described in C. Kormann et al., J. Phys. Chem. 92, 5196 (1988), and a transparency of at least 99% measured in a 5 wt. % aqueous/hydrochloric acid solution between 400 and 700 nm in 180°/d geometry at a layer thickness of 10 μm. “Monodisperse” means that the collective particles typically have a range of maximum dimension, or diameter, that varies by less than a factor of ten (×10), and the collective particles will more typically less than a two times (×2) variation in size. Although not at all necessary for their photocatalytic action, and not absolutely necessary for the formation of a sol and the use of same as a coating, it becomes increasingly harder to get uniform quality results with wide variations in the TiO 2 starting material, and to that extent some homogeneity is preferred.
[0050] The (nanoparticulate) particles of titanium dioxide (within the coating according to the invention) may also be themselves coated with 0.1 to 1000 wt. %, preferably with 5 to 200 wt. %, relative to the TiO 2 , of at least one oxide, hydroxide or hydrous oxide compound of aluminum, silicon, zirconium, tin, magnesium, zinc, cerium and phosphorus.
[0051] The present invention also contemplates a transparent titanium dioxide nanoparticulate liquid coating containing (i) a sol-forming medium and (ii) a sol-forming amount, not exceeding about 20 wt. %, of the nanoparticulate titanium dioxide in accordance with (other aspects of) the invention. The sol-forming medium preferably comprises (i) water, (ii) an alcohol containing 1 to 10 carbon atoms and at least one hydroxide group per molecule, or (iii) a mixture thereof.
[0052] 1.1 Process for the Production of Nanoparticulate Titanium Dioxide, and a Sol Suitably Used as a Coating
[0053] Therefore, in one of its aspects the present invention is embodied in a process for the production of the nanoparticulate titanium dioxide (TiO 2 ), from which TiO 2 may be produced a sol suitably used as a coating.
[0054] In the preferred process (i) an alkaline-reacting liquid is mixed with (ii) an aqueous solution of titanyl sulfate, optionally containing sulfuric acid, at elevated temperature until the resultant mixture reacts acidically and is neutralized to a pH of approximately between 5 and 9, and more preferably approximately 6.5-7.5, forming (or precipitating) flocculates of titanium dioxide nanoparticles.
[0055] The mixture obtained is cooled. The resulting titanium dioxide flocculate formed is isolated through separation by filtration or some other method conventionally recognized in the art, with the isolated nanoparticulate flocculate washed in water and then isolated again. This water-washing step is important. Maximum dispersion into a sol, as will next be discussed, cannot be obtained but that the titanium dioxide nanoparticulate flocculate is first washed in water (before being washed in an acid or alkali, immediately next discussed).
[0056] The isolated and water-washed nanoparticulate flocculate is then washed in an acid or an alkali, isolating as a product an acidic or alkaline titania concentrated slurry or cake.
[0057] This isolated titania concentrate is dispersed in a polar sol-forming medium to make a sol that is suitable as a coating. The sol is distinguished by, inter alia, being transparent. The sol also beneficially contains less than 0.1 wt. % of carbon, which is as good as or better than any titania sol of the prior art. Finally, this sol will prove to have some very interesting properties, immediately next discussed, when it is applied to a surface.
[0058] The transparent titania sol is suitable for application to a surface, including the surfaces of powders or of granules. After being coated with the sol, the surface may optionally be prepared by neutralizing with the required acidic or alkaline reacting compound, and subsequent washing with water. Notably, and importantly, neither the titania concentrate nor the TiO 2 of which it is comprised end up on the surface at anything like uniformity at the molecular level. Instead, the titania concentrate, or TiO 2 , becomes applied to the surface as independent nanoparticles or small agglomerations of nanoparticles, or spots, or islands, that are in size and number dependent upon (i) the density of the titania concentrate in the sol and (ii) the area coated. These nanoparticles, or spots, or islands, are commonly widely separated relative to their own size. Although this uniformity might initially be perceived to be an undesired condition, it is in fact beneficial—see the next section 2.
[0059] After being coated with the sol, the surface may further optionally be coated with 0.1 to 1,000 wt. %, and more preferably with 5 to 200 wt. %, relative to TiO 2 , of at least one oxide, hydroxide or hydrous oxide compound of aluminum, silicon, zirconium, tin, magnesium, zinc, cerium and phosphorus. The surface is still further optionally (i) dried and/or (ii) annealed.
[0060] The polar sol-forming medium preferably comprises water, an alcohol containing 1 to 10 carbon atoms and at least one hydroxide group per molecule, or a mixture thereof.
[0061] Perhaps surprisingly, the nanoparticulate TiO 2 coating according to the invention may be successfully produced within a large scale industrial process, namely TiO 2 pigment production using the sulfate process, and is thus very simple and economically viable.
[0062] The filter residue obtained (after the washings) and the coating obtained (after application of the sol film) using the process according to the invention may be inorganically and/or organically post-treated.
[0063] In principle, any aqueous titanyl sulfate solution is suitable as the educt. Said solution may optionally contain sulfuric acid. Contamination by metals which form soluble sulfates and chlorides, such as for example iron, magnesium, aluminum and alkali metals do not in principle disrupt the production process, unless the stated elements have a disadvantageous effect even in trace quantities in the intended application. It is thus possible to perform the process according the invention on a large industrial scale. Black liquor, as is obtained from the sulfate process by digesting ilmenite and/or titanium slag with sulfuric acid, dissolving the resultant digestion cake in water and performing clarification, may for example be used as the educt.
[0064] The production process according to the invention is, however, not restricted to black liquor as the educt. Examples of other processes for the production of titanyl sulfate solution suitable as an educt include:
[0065] 1) dissolution of commercial grade titanyl sulfate in water;
[0066] 2) dissolution/digestion of titanium dioxide and TiO 2 hydrates, for example orthotitanic acid, metatitanic acid, in H 2 SO 4 ;
[0067] 3) dissolution/digestion of alkali metal and magnesium titanates, also in hydrous form, in H 2 SO 4 ;
[0068] 4) reaction of TiCl 4 with H 2 SO 4 to form TiOSO 4 and HCl, as described in DE-A 4 216 122.
[0069] The products, in particular those from 1), 2) and 3), are preferably used as titanyl sulfate solutions when traces of foreign metals (for example iron) are not desired in the product according to the invention.
[0070] In order to achieve economically viable operation, the titanyl sulfate solutions to be used according to the invention preferably contain 100 to 300, and more particularly preferably 170 to 230 g of titanium/l, calculated as TiO 2 .
[0071] Aqueous solutions of ammonium hydroxide, sodium hydroxide, or potassium hydroxide are preferably used as the alkaline-reacting liquid; it is, in principle, also possible to use carbonates of sodium, potassium and ammonium, but these are less suitable due to vigorous evolution of CO 2 . Ammonium hydroxide solution is particularly preferred as sodium and potassium ions are not introduced as a contaminant and is used to illustrate performance of the process in greater detail.
[0072] The quantity of ammonia should be calculated such that the reaction medium at the end of step a) has a final pH of approximately between 5 and 9, and more preferably between 6.5 and 7.5.
[0073] The ammonia is preferably used as an ammonium hydroxide solution having a concentration of approximately between 1 to 8 molar NH 4 OH and more preferably between 1 to 4 molar NH 4 OH.
[0074] The reaction of ammonium hydroxide solution with the titanyl sulfate solution preferably proceeds in such a manner that the ammonium hydroxide is added to a solution of titanyl sulfate, heated to approximately 60 to 1000° C.
[0075] Preferably the reaction of the ammonium hydroxide and titanyl sulfate solution can also be carried out by adding the two reactants simultaneously and mixing them with stirring at temperatures of between 60 and 100° C.
[0076] This reaction of the titanyl sulfate solution should preferably be performed with vigorous stirring and at temperatures of 60 to 100° C.
[0077] The addition of the ammonium hydroxide to the titanyl sulfate solution should preferably take no longer than 30 minutes.
[0078] Once reacted, the resultant mixture should preferably be quenched to temperatures of below 60° C. and then optionally stirred for {fraction (1/4)} to 1 hour at this temperature.
[0079] In summary, the production of the sol suitable as a coating, and the sol so produced, has myriad, and distinguishing, advantages. The sol is uniquely transparent while achieving the desirably low carbon of the best prior art titania sols. The yield in making the sol is unexcelled; virtually 100% of the precipitated titanium flocculates are taken up into the sol. The process of making the sol is readily scalable to industrial scale. Finally, and as a seemingly subtle differentiation in the sol the use and benefit of which is unanticipated in the prior art, the sol, when used as a coating, will not deposit its titanium dioxide uniformly (upon a coated surface, which may be a particle) but will instead lay down the titanium dioxide in microparticles, or spots, or islands. The very significant advantage of this is immediately next discussed in section 2.
[0080] 2. Composite Photocatalytic Materials
[0081] In its aspect concerning the realization of composite photocatalytic materials, the preferred material of the present invention includes, as previously stated, (1) bodies that are most preferably in the form of carrier particles and that are made of material that do not interfere with photocatalytic activity and do not adversely interact with other components in an end-use application. These (1) bodies that are non-deleterious to photocatalytic reaction have (2) surfaces that are photocatalytic, forming thus a composite photocatalytic material.
[0082] Moreover, these (2) surfaces are not substantially evenly possessed of photocatalytic material and photocatalytic action, but preferably have such photocatalytic material highly specifically located in “spots”, or “islands” that may themselves be either 2 or 3-dimensional.
[0083] To realize these “islands” of photocatalyst, the (2) surfaces of the (1) bodies, or carrier particles, are not made from continuous films of photocatalytic material, but are instead made by attaching discrete nanoparticles of photocatalyst. These nanoparticles of photocatalyst are preferably smaller—normally 1×10−9 to 1×10−7 in diameter—than are the carrier particles themselves, which are commonly about 1×10−7 to 1×10−2 meters in diameter, depending on application.
[0084] Both the size of the (2) carrier particles, or bodies, and the density of the spots, or islands, of (1) surface photocatalytic material are a function of intended application. An exemplary application of a carrier large particle might be for use in a gravel-like roof coating where it is substantially desired only that large, ground-observable, patches of algae should not grow on the roof. In this application the photocatalytic spots, or islands, might also be relatively widely separated, the main goal not being to kill every bacteria or algal cell on the roof, but to prevent formation of a bio-film. Exemplary applications of small carrier particles include the lips of a swimming pools, bathroom tiles, and hospital coatings where it is desired to avoid all bacterial growth whatsoever. Not only are the carrier particles small, but the photocatalytic spots, or islands, may be relatively close spaced (although normally not continuous).
[0085] As an aside, the photocatalyst of the present invention is generally not intended for use in liquids other than coatings, and certainly not for antiseptic solutions where photocatalyst suspensions kill microbes or algae on surfaces. The only time the inventor has used photocatalyst suspensions was in lab tests wherein algae was suspended in water and photocatalyst particles were then introduced into the water to see “for a first glimpse” whether the photocatalyst killed the algae. However, it is contemplated that the photocatalyst of the present invention could be dispersed in water to destroy microbial suspensions. One such application could be to destroy harmful algae blooms in lakes and bays. The three main benefits of using photocatalyst of the present invention in natural waterways would be (i) low toxicity to higher life forms, (ii) limited persistence in the environment (the concentrated contaminants of natural water systems tend to foul the photocatalyst, inactivating it over time), and (iii) excellent dispersion properties in water (in contrast to poor dispersion for virgin photocatalyst).
[0086] Accordingly, by incorporating but minute amounts of dispersed photocatalytic nanoparticles solely upon the surfaces of carrier particles—most typically in an amount of less than 20% and more typically 5% by weight in the composite material—these dispersed photocatalytic nanoparticles, and diverse surfaces coated with the composite material, are highly effective in killing microorganisms, including both algae and bacteria, in the presence of light in the visible or ultraviolet wavelengths. Indeed, by attaching microparticles of preferred photocatalytic materials of titanium dioxide, zinc oxide and tungsten oxide and mixtures thereof onto the surface of particles of silicate and carbonate powders and sands, mineral and mineral composites, inorganic pigments, construction aggregates, polymers and like common materials in an amount of less than 10% by weight, the composite particles so formed are at least 50% as effective in killing algae and bacteria as are the pure photocatalysts themselves. Accordingly, there is at least a five-to-one (5:1), and more typically a twenty-to-one (20:1), gain in efficiency in the usage of the photocatalytic materials—which are greatly more expensive than are the materials from which the carrier particles are made.
[0087] The composite photocatalytic materials, preferably particulate materials, may themselves be combined with any of dispersants, carriers, binders and the like to make any of aqueous solutions, coatings, paints and the like as exhibit any of algicidal, fungicidal, and/or anti-bacterial effects. Liquids, aggregates and solids incorporating the composite photocatalytic materials of the present invention may be, for example, coated or painted onto, by way of example, the interior and exterior surfaces of buildings and swimming pools.
[0088] Although no theory of the operation of the composite photocatalytic materials of the present invention is necessary to make these materials, nor to take advantage of their operational characteristics, it is possible to speculate on the operation of the materials of the present invention. It is hypothesized that only a minute microparticle of pure photocatalytic material such as titanium dioxide, zinc oxide and tungsten oxide and mixtures thereof is necessary to adversely affect a much larger bacterium, or a cell of an algae; that it is not the total amount of photocatalyst that does the damage to lower life forms, but the manner in which a photocatalyst is deployed against these life forms.
[0089] Apparently it is not necessary for control of simple life forms to expose in the presence of light the entirety of the life form to a photocatalyst in order to enjoy a prophylactic effect. It is apparently sufficient for a prophylactic effect to expose only a minute region of the life form. It may even be the case that a bacterium or an algae will retreat from an extensive area of photocatalyst with less damage than it will sustain when exposed, hypothetically for a longer time, to but a microscopic spot, or particle, or photocatalyst to which its primitive sensory system is insufficiently sensitive. The present invention suggests that large surfaces, such as walls of swimming pools and buildings, should not have photocatalyst evenly applied so that, at some density of adjacent bacterial or algal life forms, a bio-film will be formed, the photocatalyst overwhelmed (including by occlusion of light energy), and the surface populated. Instead, it may be preferable that the surface act as a “trojan horse”, according areas devoid of photocatalyst—which areas are sufficient in size to be populated by one or a few bacteria or algal cells until these bacteria or algae grow and/or reproduce, forcing members of the incipient community into damaging contact with minute regions of photocatalyst. These minute regions, or microdots, or microparticles, of photocatalyst may, at their high concentrations, be very effective in promoting electron exchange in the presence of impinging light. They may become “hot spots” of “stinging” death to those microorganisms with which they come into contact.
[0090] The mechanism(s) of photocatalytically-induced fungicidal, bacteriocidal and like effects are poorly understood, but the present invention suggests that there is more to the conservative and focused deployment of photocatalysts than simply saving money by minimizing usage. The present invention suggests that photocatalyst should be parsimoniously used as a microbial rapier—the point of which can be deadly to microbial life—instead of as a bludgeon by which the substantial surface of a microbe is substantially evenly irritated in a manner that may not prove fatal to the microbe.
[0091] 2.1 A Composite Photocatalytic Material
[0092] Accordingly, in another of its aspects the present invention is embodied in a composite body exhibiting a photocatalytic effect. The body has (i) a core consisting essentially of a material without deleterious photocatalytic effect on the composite body nor adverse interaction with other. components in an end-use application, and (ii) a photocatalytic material upon the surface of the core. This photocatalytic material is less than 20% by weight of the combined photocatalytic material and the core.
[0093] The core is a preferably a particle, and more preferably a particle of less than 1 (one) centimeter in diameter. Meanwhile, the photocatalytic material is preferably a multiplicity of particles each of which is preferably of diameter less than one hundred (100) nanometers. By this construction the composite body is also a particle.
[0094] The core preferably consists essentially of a material, nondeleterious to photocatalytic reactions, drawn from the group consisting of silicates and carbonates, mineral and mineral composites, metal oxides, inorganic pigments, and construction aggregates. Alternatively, the core may consist essentially of a polymer. The polymer core is preferably drawn from the group consisting essentially of acrylics, acrylonitriles, acrylamides, butenes, epoxies, fluoropolymers, melamines, methacrylates, nylons, phenolics, polyamids, polyamines, polyesters, polyethylenes, polypropylenes, polysulfides, polyurethanes, silicones, styrenes, terephthalates, vinyls.
[0095] The photocatalytic material is preferably drawn from the group of metal compound semiconductors consisting essentially of titanium, zinc, tungsten and iron, and oxides of titanium, zinc, tungsten and iron, and strontium titanates. This compound semiconductor photocatalytic material. may be combined with a metal or metal compound drawn from the group. consisting of nickel, cobalt, zinc, palladium, platinum, silver, and gold. Most preferably, the photocatalytic material is drawn from the group of metal compound semiconductors consisting essentially of anatase titanium dioxide and zinc oxide.
[0096] The composite photocatalytic material is preferably in the form of particles having a diameter from 100 nanometers to 1 centimeter, which diameter depends upon the core size selected and the intended end-use application.
[0097] The weight of the photocatalytic material is preferably less than 20% of the weight of the core, and more preferably less than 10% of the weight of the core.
[0098] The composite photocatalytic material in accordance with the present invention is usefully incorporated in other compositions. When so incorporated, it is preferably so incorporated in amounts from 0.001% to 85% by volume. The composite photocatalytic material may be incorporated with, or on, one or more materials from the group of building materials consisting of concrete, cement, stucco, masonry, roofing shingles, wall shingles, building siding, flooring materials and swimming pool surfaces. The composite photocatalytic material may be incorporated in a composition that is effective as an anti-fouling coating. For example, it may be incorporated in a concrete coating effective in killing by contact algae, fungus and/or bacteria on surfaces.
[0099] Most typically, at a proportion by weight in the composite particle of less than 10%, the efficacy of the photocatalytic material within the composite particles to kill by contact both algae and bacteria upon surfaces is at least one-half (0.5) as good as is the efficacy of this same photocatalytic material in purest form to kill. In other words, at least equal killing effect is realized with at least a five to one (5:1) reduction in the amount of photocatalytic material used (when this photocatalytic material is upon the surface of the composite particles).
[0100] [0100] 2 . 2 Methods of Making Composite Photocatalytic Particles
[0101] In yet another of its aspects (concerning the making and use of photocatalytic materials), the present invention is embodied in methods of making composite photocatalytic particles.
[0102] In one method an aqueous slurry of first particles—these particles consisting essentially of a material without deleterious photocatalytic effect on the composite particle nor adverse interaction with other components in an end-use application, and having a size in the range from 100 nanometers to 1 centimeter diameter—is prepared.
[0103] To this slurry is added a colloidal suspension of 0.1% to 60% by weight second particles, which second particles consist essentially of photocatalytic material having diameters in the range from 1 to 100 nanometers. The combined weight of second particles in the colloidal suspension is less than 20%, and more preferably less than 10%, of the combined weight of the first particles that are within the aqueous slurry.
[0104] The aqueous slurry and the colloidal suspension is mixed so that the photocatalytic material second particles attach through van der Waals forces or chemical fusion to the nondeleterious material first particles, forming a slurry of composite particles. In these composite particles the relatively smaller photocatalytic material second particles are located upon the surfaces of the relatively larger, nondeleterious material, first particles.
[0105] The photocatalytic material is in weight preferably less than 20%, and more preferably less than 10%, of the first particles. The added colloidal suspension added is preferably from 0.1% to 60% by weight second particles. The colloidal suspension added is preferably of the highest solids concentration at which the suspension is stable, normally being in the range from 14% to 50% by weight.
[0106] The pH of the-mixing is often beneficially adjusted so that both the photocatalytic material second particles and the nondeleterious material first particles are displaced to the same direction—whether above or below—from their respective isoelectric points (those points at which the particles have a neutral net charge). Furthermore, the nondeleterious material first particles and the photocatalytic material second particles may also have opposite charge.
[0107] The adding of the colloidal suspension of second particles, or the mixing of the aqueous slurry and the colloidal suspension, or both the adding and the mixing, may optionally transpire in the presence of at least one dispersant.
[0108] The method may continue with one or more well-known finishing steps such as filter, wash and/or dry the composite photocatalytic particles.
[0109] When the aggregation of composite photocatalytic particles is dried, composite particles with heat resistant cores are then preferably annealed in a kiln to create stronger fusion bonds between the photocatalytic material second particles and the nondeleterious material first particles and/or to improve the photocatalytic nature of the photocatalyst by changing its crystalline form. Moreover, the annealed composite photocatalytic particles are preferably rapidly cooled to ambient room temperature; this may be simply accomplished by removing the hot material from the kiln to facilitate heat transfer away from the material. The time period of this cooling is necessarily dependent, at least in part, upon the temperature of the annealing and the amount of the composite photocatalytic particles. However, it is preferably less than six hours. Since this forced rapid cooling might normally be considered to induce fracturing in metals, it is uncommonly applied to the materials (including metal oxides) of the present invention. However, it has benefit in that it increases photocatalytic activity.
[0110] 3. Photocatalytic Aggregate Particles
[0111] In still yet another of its aspects, the present invention contemplates highly photocatalytic aggregate particles comprised of an extender particle with discrete photocatalytic titanium oxide particles exposed on the surface. The extender particle reduces the amount of premium photocatalyst required to achieve desired photocatalytic activity in a finished product. The discrete nature of the photocatalytic titanium oxide particles, applied in sufficient number, increases the photoactivity of the aggregate particles by increasing their photoactive surface area verses the surface area provided by a relatively flat continuous coating. The aggregates of this invention exhibit an inhibitory effect on surface-borne microorganisms when the mixtures are incorporated into building materials such as masonry, roofing shingles, siding, and antifouling coatings. Further, the aggregate particles show improved handling and dispersion in coating preparations versus virgin photocatalyst.
[0112] The invention also contemplates processes for making such aggregates, slurries of the aggregates, coatings, building materials, and masonry containing the aggregates.
[0113] 3.1 The Preferred Photocatalytic Aggregates
[0114] The preferred aggregate particles of the present invention—generally comprised of an extender particle with discrete photocatalytic titanium oxide particles exposed on the surface, which exhibit antifouling properties and improved dispersion in slurries and coatings—consist essentially of photocatalytic titanium oxide, preferably titanium dioxide in the anatase crystalline form, at less than about 20% by weight, preferably less than 10% by weight, and more preferably less than 6% by weight, and an extender particle at greater than 20% by weight. Preferred extender particles include silicate and carbonate powders, mineral and mineral composites including calcined clay and wollastonite, metal oxides including zinc oxide, inorganic pigments, and construction aggregates including roofing granules.
[0115] In one preferred embodiment, colloidal anatase titanium dioxide in an amount less than 6 weight % is dispersed on the surface of crystalline silica powder having an average particle diameter of 0.7 to 5 microns. In another preferred embodiment, colloidal anatase titanium dioxide in an amount less than 6 weight % is dispersed on the surface of zinc oxide powder having an average particle diameter of 0.7 to 5 microns.
[0116] This invention also includes anti-fouling building products, including coatings and masonry compositions, comprising aggregate photocatalytic particles of this invention at a volume concentration of 0.001% to 85% where the anti-fouling coatings and masonry resist the growth of microorganisms when U.V. or visible light energy is present to activate the aggregate photocatalytic particles. Building products include roofing granules, roofing shingles, building siding, wall shingles, hard flooring, and swimming pool surfaces.
[0117] 3.2 Preferred Processes for Producing Photocatalytic Aggregates
[0118] Several different processes for making the above-described aggregate photocatalytic materials are preferred. In one embodiment, an aqueous slurry of extender particles are mixed with a solution of titanyl sulfate and by the addition of an alkaline reacting agent, discrete titanium dioxide particles are deposited onto the extender particles.
[0119] In another embodiment, an alkaline or acidic titania sol is mixed with extender particles where the particles in the titania sol have an average diameter size within the range of about 1 to about 100 nanometers. The solution is maintained such that the extender particles and the sol particles are both above or below their respective isoelectric points such that substantially discrete particles of titanium dioxide are dispersed onto the surfaces of the extender particles in an amount less than 20 weight % based on aggregate particle weight.
[0120] These and other aspects and attributes of the present invention will become increasingly clear upon reference to the following drawings and accompanying specification.
BRIEF DESCRIPTION OF THE DRAWINGS
[0121] [0121]FIG. 1, consisting of FIG. 1 a through FIG. 1 c , are scanning electron micrographs of silica particles with a coating of nano-particulate TiO 2 at 4% by wt. silica according to the invention.
[0122] [0122]FIG. 2, consisting of FIGS. 2 a through FIG. 2 d , are scanning electron micrographs of silica particles with a coating of nano-particulate TiO 2 at 0.5% by wt. silica according to the invention.
[0123] [0123]FIG. 3 is a graphical depiction of three example arrangements of discrete photocatalytic particles, particularly titanium dioxide particles, on the surface of an extender, or carrier, or core particle so as to form a photoactive antifouling aggregate, where FIG. 3 a shows discrete particles of titanium oxide partially covering larger extender particles, FIG. 3 b shows discrete flocculates of titanium oxide particles partially covering extender particles, and FIG. 3 c shows discrete titanium oxide particles fully covering larger extender particles.
[0124] [0124]FIG. 4 is a transmission electron micrograph of a composite photocatalytic particle having substantially discrete particles of anatase titanium dioxide dispersed on the surface of a silica particle created using a compaction milling device.
[0125] [0125]FIG. 5 is a bar chart illustrating the algae-inhibiting effect of photoactive antifouling aggregate comprising 25 weight % non-colloidal photoactive zinc oxide and 75 weight % colloidal anatase titanium dioxide.
[0126] [0126]FIG. 6 is a bar chart showing the inhibiting effect of an the aggregate of FIG. 5 on the growth of E. coli bacteria.
[0127] The following examples are intended to illustrate the invention in greater detail.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0128] The following description is of the best mode presently contemplated for the carrying out of the invention. This description is made for the purpose of illustrating the general principles of the invention, and is not to be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.
[0129] Although specific embodiments of the invention will now be described, it should be understood that such embodiments are by way of example only and are merely illustrative of but a small number of the many possible specific embodiments to which the principles of the invention may be applied. Various changes and modifications obvious to one skilled in the art to which the invention pertains are deemed to be within the spirit, scope and contemplation of the invention as further defined in the appended claims.
[0130] 1. Process for the Production of Nanoparticulate Titanium Dioxide
[0131] It will be recalled that one embodiment of the present invention is as a process for the production of the nanoparticulate titanium dioxide coating. The preferred process includes
[0132] a) mixing an alkaline-reacting liquid with an aqueous solution of titanyl sulfate, optionally containing sulfuric acid, at elevated temperature until the resultant mixture reacts acidically and is neutralized to a pH of approximately between 5 and 9, and more preferably approximately 6.5-7.5, forming flocculates of titanium dioxide nanoparticles;
[0133] b) cooling the mixture obtained in step a);
[0134] c) isolating, through filtration or some other method conventionally recognized in the art, the resulting titanium dioxide nanoparticle flocculate formed in step b);
[0135] d) washing said nanoparticle flocculate in water and isolating again;
[0136] e) washing said nanoparticle flocculate in an acid or alkali and isolating the product as an acidic or alkaline titania concentrate;
[0137] f) dispersing said titania concentrate in a polar sol-forming medium to make a transparent sol;
[0138] g) applying a film of the titania sol to a surface, including powders or granules;
[0139] h) optionally neutralizing said surface with the required acidic or alkaline reacting compound and subsequently washing said surface with water;
[0140] i) optionally coating said titania-coated surface with 0.1 to 1,000 wt. %, preferably with 5 to 200 wt. %, relative to TiO 2 , of at least one oxide, hydroxide or hydrous oxide compound of aluminum, silicon, zirconium, tin, magnesium, zinc, cerium and phosphorus;
[0141] j) optionally drying and annealing said surface.
[0142] The sol-forming medium referred to in step f) preferably comprises water, an alcohol containing 1 to 10 carbon atoms and at least one hydroxide group-per molecule, or a mixture thereof.
[0143] The nanoparticulate TiO 2 coating according to the invention may surprisingly also successfully be produced within a large scale industrial process, namely TiO 2 pigment production using the sulfate process, and is thus very simple and economically viable.
[0144] The filter residue obtained (after step d or e) and the coating obtained (after step g) using the process according to the invention may be inorganically and/or organically post-treated.
[0145] In principle, any aqueous titanyl sulfate solution is suitable as the educt. Said solution may optionally contain sulfuric acid. Contamination by metals which form soluble sulfates and chlorides, such as for example iron, magnesium, aluminum and alkali metals do not in principle disrupt the production process, unless the stated elements have a disadvantageous effect even in trace quantities in the intended application. It is thus possible to perform the process according to the invention on a large industrial scale. Black liquor, as is obtained from the sulfate process by digesting ilmenite and/or titanium slag with sulfuric acid, dissolving the resultant digestion cake in water and performing clarification, may for example be used as the educt.
[0146] The production process according to the invention is, however, not restricted to black liquor as the educt. Examples of other processes for the production of titanyl sulfate solution suitable as an educt are:
[0147] 1) dissolution of commercial grade titanyl sulfate in water;
[0148] 2) dissolution/digestion of titanium dioxide and TiO 2 hydrates, for example orthotitanic acid, metatitanic acid, in H 2 SO 4 ;
[0149] 3) dissolution/digestion of alkali metal and magnesium titanates, also in hydrous form, in H 2 SO 4 ;
[0150] 4) reaction of TiCl 4 with H 2 SO 4 to form TiOSO 4 and HCl, as described in DE-A 4 216 122.
[0151] The products, in particular those from 1), 2) and 3), are preferably used as titanyl sulfate solutions when traces of foreign metals (for example iron) are not desired in the product according to the invention.
[0152] In order to achieve economically viable operation, the titanyl sulfate solutions to be used according to the invention preferably contain 100 to 300, particularly preferably 170 to 230 g of titanium/l, calculated as TiO 2 . Aqueous solutions of ammonium hydroxide, sodium hydroxide, or potassium hydroxide are preferably used as the alkaline-reacting liquid; it is, in principle, also possible to use carbonates of sodium, potassium and ammonium, but these are less suitable due to vigorous evolution of CO 2 . Ammonium hydroxide solution is particularly preferred as sodium and potassium ions are not introduced as a contaminant and is used to illustrate performance of the process in greater detail.
[0153] The quantity of ammonia should be calculated such that the reaction medium at the end of step a) has a final pH of approximately between 5 and 9, and more preferably between 6.5 and 7.5.
[0154] The ammonia is preferably used as an ammonium hydroxide solution having a concentration of approximately between 1 to 8 molar NH 4 OH and more preferably between 1 to 4 molar NH 4 OH.
[0155] The reaction of ammonium hydroxide solution with the titanyl sulfate solution preferably proceeds in such a manner that the ammonium hydroxide is added to a solution of titanyl sulfate, heated to approximately 60 to 100° C.
[0156] Preferably the reaction in step a) can also be carried out by adding the two reactants simultaneously and mixing them with stirring at temperatures of between 60 and 100° C.
[0157] Step a) should preferably be performed with vigorous stirring and at temperatures of 60 to 100° C.
[0158] The addition of the ammonium hydroxide in step a) should preferably take no longer than 30 minutes.
[0159] After step a), the mixture should preferably be quenched to temperatures of below 60° C. and then optionally stirred for {fraction (1/4)} to 1 hours at this temperature.
[0160] The resultant mixture is turbid to a greater or lesser extent and comprised of flocculates of nanoparticlulate TiO 2 .
[0161] After cooling, the flocculate is isolated by filtration or other conventional separation technique and then washed with water to remove contaminating sulfur compounds and other water-soluble contaminants. After isolating the TiO 2 again, the flocculate is washed with a monobasic acid or alkali to remove further contaminants and introduce the ions necessary for sol formation.
[0162] The flocculate is nanoparticulate titanium dioxide having a particle size of between 1 and 100 nm, containing less than 0.1 wt. % of carbon and having a transparency of at least 99% (see above).
[0163] Addition of the ammonium hydroxide in step a) results in an initial increase in viscosity of the reaction medium as the resultant bulky flocculates form. Continued stirring distributes the flocculates more evenly resulting in a decrease in viscosity. The resulting flocculates may be separated simply by settling, i.e. standing undisturbed for at least 12 hours and decantation. Due to their size (preferably greater than 1 micron), the resultant bulky flocs may readily be centrifuged and filtered.
[0164] The precipitate is then washed with water, preferably by dispersing the precipitate in 3 to 10 times its weight in water, and then isolating the precipitate through filtration or other conventional separation method.
[0165] The said precipitate is then washed in a monobasic acid or alkali solution by preferably dispersing the precipitate in 1 to 6 times its weight in acid or alkali and then isolating the precipitate through filtration or other conventional separation method as is know in the art. The preferred washing agent is hydrochloric acid, which is used to illustrate the further processing in greater detail. The same procedure should be used with other acids and alkali.
[0166] The HCl concentration in the hydrochloric acid should preferably be no less than 3 molar, preferably 3 to 6 molar, and particularly preferably 4 to 6 molar.
[0167] Depending upon the filter unit and starting material, the acid or alkali-washed titania concentrates typically contain 4 to 40 wt. % of TiO 2 , the remainder being wash acid or wash alkali, moisture and possibly small quantities of contaminants. The nanoparticles may be stored as acidic or alkaline concentrates in air-tight containers at room temperature without change for some weeks, and as necessary, suspended in a sol-forming medium for producing sol coatings.
[0168] Once redispersed in water, the titania concentrates yield “solutions” (sol coatings) which, apart from slight opalescence (Tyndall effect), are clear, transparent and colorless or nearly colorless. The TiO 2 is present in these sol coatings exclusively as nano-particles having a diameter of between 1 and 100 nm.
[0169] It is possible in this manner to produce strongly acidic or strongly alkali, virtually completely transparent (water-clear) sol coatings containing up to approximately 20 wt. % of TiO 2 . At a concentration of 5 wt. % of TiO 2 , the transparency of the sol coatings is at least 99% over the visible range of the spectrum from 400 nm to 700 nm wavelengths (measured in 180°/d geometry at a layer thickness of 10 μm).
[0170] Generally, a sol coating may be created my combining 2 to 3 parts by weight water with one-part by weight acidic or alkaline concentrate. Such sol coatings are also generally stable for some weeks. As much as 10 to 20 parts additional water may be added to further dilute the sol coating.
[0171] Similar sol coatings my also be produced in polar organic solvents, primarily in mono- and polyhydric short-chain alcohols, such as for example ethanol and 1,4-butanediol. The alcohols preferably contain 1 to 10 carbon atoms per molecule.
[0172] An alternative method of carrying out the invention is forming an aqueous colloidal coating by combining water with the acidic or alkali titania concentrate of this invention and adding at least one dispersant. The dispersant may also be added simultaneously with the water. The dispersant can be selected from those described in U.S. Pat. No. 5,393,510, the teachings of which are incorporated herein by reference. Examples of dispersants include alcohol amines such as 2-amino-2-methyl-1-propanol, 2,2′,2″-nitrilotrisethanol, 2,2′-iminobisethanol, 2-aminoethanol and the like, and 1-amino-2-propanol, polyacrylates, citric acid and tetrapotassium pyrophosphate (TKPP) and the like. Typically a combination of the above dispersants is preferred in an amount of about 0.05 to about 5% based on TiO 2 weight, or based on total solids weight when the coating is mixed with powders or granules.
[0173] Spread thinly onto a surface, the nano-particulates of the sol coatings will be attracted to the surface by van der Waals' forces and may be further anchored to the surface material by stronger chemical bonds such as fusion bonds. Coatings may be applied to continuous solid surfaces by dip-coating, rolling, brushing, or other such application procedure. Coatings may be applied to particles, such as powders and granules, by direct mixing, fluid bed application, or other suitable application procedure. It has been found that uniform surface coatings of nano-particulate TiO 2 on powders and granules is best achieved by maintaining the to-be-coated particles and the colloidal particles at both above or below their respective isoelectric points such that substantially discrete particles of titania are evenly dispersed onto the surfaces of the target particles. In one preferred embodiment of this invention, titania suspended in a sol medium containing HCl is added to particulates pre-wetted with a solution of HCl resulting in evenly dispersed nanoparticles of TiO 2 on the particulates.
[0174] Where acidic or alkali residue may impact the performance of the nano-coating, the coated surface may be further washed with a neutralizing agent (such as a dilute ammonium hydroxide solution when the residue is acidic or a dilute solution of HCl when the residue is alkali) and then the resulting surface washed with water to remove any remaining contaminants.
[0175] In the event that a reduction in photoactivity is desired, the nanoparticles may be inorganically coated (post-treated), wherein, as with pigment TiO 2 , coating is performed-with oxides, hydroxides or hydrous oxides of one or more of the following elements: Al, Si, Sn, Mg, Zn, Ce, P. The quantities to be used amount to 0.1 to 1000, preferably to 5 to 200 wt. %, relative to TiO 2 .
[0176] Inorganic post-treatment is not necessary, and generally undesirable, if the product is used as a catalyst for the photochemical degradation of organic compounds (polymers, pollutants) or as a support for dye solar cells. However, surprisingly it has been found that a coating of silicate precipitated onto the nano-coating from a solution of sodium silicate has a limited impact on photocatalytic activity when the amount of silicate precipitated is approximately less than 5 times the amount of TiO 2 in the nano-coating. The silicate is preferably precipitated from a solution of sodium silicate containing 0.05% to 2% silica by wt. Precipitation is accomplished by titrating the sodium silicate solution with an acid, such as HCl, to a neutral pH of about 7. The surface is then preferably washed to remove contaminants. Such silicate coatings may be desired to further enhance the adhesion of the nano-coating to a surface.
[0177] As a final step in the process for making the nano-coating, the coated surface may be dried and annealed to drive off moisture, crystallize the TiO 2 and better fuse the nanoparticulate TiO 2 to the surface. The photocatalytic activity of the coating may be optimized by annealing the coating at a temperature of approximately between 400° C. and 650° C. for 30 minutes to 5 hours. Photocatalytic activity may be reduced by annealing at a temperature above 700° C. which temperature induces a crystalline phase change in the TiO 2 from the anatase form to the less photocatalytic rutile form. Annealing and its effect on photocatalytic activity is discussed in further detail in L. Gomathi Devi's “Photocatalytic degradation of p-amino-azb-benzene and p-hydroxy-azo-benzene using various heat treated TiO 2 as the photocatalyst”, J. of Photochem. and Photobio. A: Chem. 121 ( 1999), 141-145.
[0178] In applications in which acid excesses have a disruptive effect, the sol coatings according to the invention may subsequently be stabilized in the neutral pH range in a manner known in principle, for example with acetylacetone (WO 93/05875) or with hydroxycarboxylic acids (EP-A 518 175).
[0179] The coating of nanoparticulate titanium dioxide is used as a photocatalyst to prevent fouling from microorganisms on surfaces, as a U.V. screening agent, and as a flame retardant.
[0180] 1.1 Example of the Process for the Production of Nanoparticulate Titanium Dioxide Coatings
[0181] An example of the process of the invention for the production of nanoparticulate titanium dioxide coatings is as follows:
[0182] Recommended Laboratory supplies and equipment for laboratory preparation of nanoparticulate titanium dioxide coatings include (i) a fume hood, (ii) 2 heated stir plates, (iii) a glass stir rod, (iv) 100, 250 and 1000 ml liter beakers, (v) a 1000 ml filtration flask, (vi) 10 ml and 100 ml graduated cylinders, (vii) cellulose nitrate filtration paper, 90 mm circles, 0.45 micron, (viii) teflon coated magnetic stir bars, (ix) an aspirator or other vacuum source for filtration (x) lab balances (+−1 mg and +−0.1 mg), (xi) a container for the ice bath, (xii) a 1 liter filtration flask (Erlenmeyer with a sidearm), (xiii) a Coors-type ceramic Buchner funnel with fixed plate for 90 mm filtration paper, (xiv) a rubber gasket for the filtration flask, (xv) a mortar and pestle (100 ml minimum size for combining sol with silica), (xvi) a drying oven (to 130° C.), (xvii) a ceramic or pyrex vessel for annealing, (xviii) an annealing oven (to 650° C.), (xix) 10 ml pipettes, (xx) a pH meter or pH paper (pH 7), (xxi) a thermometer (to 100° C.), (xii) a squirt bottle for water, and (xiii) a non-metallic spatula for removing filter cake from the filter. A 1 liter vessel with temperature control and stir capability is optional.
[0183] Required chemicals include (i) deionized water, (ii) ammonium hydroxide, aq (29.6%), (iii) hydrochloric acid, aq (37%), (iv) TiOSO4 (Noah Technologies), and (v) water ice.
[0184] 210 ml water is mixed with 100 g TiOSO 4 (Noah Technologies, comprising 80.3% TiOSO 4 •2H 2 O, 8.3% free acid sulfuric, 11.4% moisture) and heated to 85° C. while stirring in a jacketed glass vessel using a mechanical stirrer. 270 ml NH 4 OH 1.91 M is slowly added over 10 minutes with continued stirring causing titania to precipitate from the solution. The stirring continues until the viscosity of the solution thins and stabilizes. The solution is then neutralized to about pH 7 with the addition of 14 ml NH 4 OH 3.81 M and stirred for an additional 15 minutes at 85° C. The suspension is then quenched to 28° C. over 20 minutes and the precipitate filtered using a 0.45 micron nitrocellulose filter. The white precipitate is then re-suspended in 1 liter water to rinse the flocculates and then filtered again. The resulting filter cake is re-suspended in 250 ml HCl 6 M and filtered again. The resulting acidic titania cake is comprised of nanoparticulate titania. The cake may be used immediately for making a colloidal titania coating or stored in an air-tight container for later use. To make a transparent colloidal coating, a quantity of the acidic titania cake (about 9% by wt. TiO 2 ) is dispersed in three times its weight in water. The stable pH range for titania sol (for sol containing 4.6% TiO2 by wt.; in the method described in this example, the sol contains 2.3% TiO2 by wt.) is 1.1 (+−0.2) −(+−0.2) pH. The titania completely precipitates from the sol at 5.2 (+−0.2) pH.
[0185] [0185]FIG. 1 a through FIG. 1 c are scanning electron micrographs showing silica particles with a coating of nano-particulate TiO 2 at 4% by wt. silica according to the above process. FIGS. 2 a through FIG. 2 d , are similar scanning electron micrographs of silica particles with a coating of nano-particulate TiO 2 at 0.5% by wt. silica according to the above process.
[0186] A perhaps more understandable view of an entire surface coating of nano-particulate TiO 2 in accordance with the above process of the present invention is within the graphical depiction of FIG. 3. FIG. 3 diagrammatically shows three example arrangements of discrete photocatalytic particles, particularly titanium dioxide particles, on the surface of an extender, or carrier, or core particle so as to form a photoactive antifouling aggregate. FIG. 3 a shows in the direction of the arrow the accumulation of discrete particles 11 of titanium oxide—by action of a sol coating—so as to partially cover larger extender particles 21 . FIG. 3 b shows in the direction of the arrow the accumulation of irregularly-shaped discrete flocculates 12 of titanium dioxide particles—again by action of a sol coating—so as to partially cover extender particles 21 . Finally, FIG. 3 c shows agglomerations 13 of discrete titanium dioxide particles 11 to fully cover the larger extender particles 21 . When it is remembered that even the smallest titanium dioxide particles—the discrete particles 11 of FIG. 3 a —contain many molecules of TiO 2 , normally more than one hundred, it is clear that the titanium dioxide is agglomerated as nanoparticles, or spots, or islands. Particularly obvious in FIGS. 3 a and 3 c —but, technically, also in FIG. 3 c —the coating is not even, and is not uniform.
[0187] 1.2 Example of the Application of a Nanoparticulate Titanium Dioxide Coating, Particularly to Silicon Powder
[0188] An example of the process of the invention for the application of a nanoparticulate titanium dioxide coating is as follows. The example is for the application of nanoparticulate TiO2 coating to silica powder.
[0189] Additional required chemicals include (vi) Min-U-Sil 5 Silica, U.S. Silica.
[0190] 2.5 ml of HCl 0.15 M is mixed with 5 g silica powder (Minucel 5 from U.S. Silica, avg. particle size 1.4 microns) to create a slurry. 2.22 g titania sol from Example 1 is then added to the slurry. 10 ml NH 4 OH 0.1 M is then stirred into the titania-coated silica slurry to neutralize it to pH 7. The resulting slurry is then filtered, re-suspended in 25 ml water to rinse, and then filtered again. The resulting cake is then dried at 130° C. for 30 minutes and then annealed at 650° C. for 4.5 hours. The resulting powder is silica coated with approximately 1% by weight nanoparticulate TiO 2 . The powder is photocatalytic which may be measured by the decolorization of the textile dye Reactive Black 5 as described in I. Arslanin's “Degradation of commercial reactive dyestuffs by heterogenous and homogenous advanced oxidation processes: a comparative study” Dyes and Pigments 43 (1999) 95-108. Examination of the powder using scanning electron microscopy demonstrates a well-dispersed coating of nanoparticulate TiO 2 having particle sizes of about 1 nm to 100 nm adhering to the silica particles. For example, see FIG. 4 which is a transmission electron micrograph of a composite photocatalytic particle having substantially discrete particles of anatase titanium dioxide dispersed on the surface of a silica particle created using a compaction milling device.
[0191] 1.3 Example of the Process of Scaling-Up for the Production of Composite Photocatalytic Particles Containing Nanoparticulate Titanium Dioxide Upon Their Surface
[0192] An example of the process of the invention for scaling-up the production of composite photocatalytic particles containing nanoparticulate titanium dioxide upon their surface is as follows:
[0193] Scaling up this process for making composite photocatalytic particles containing nanoparticulate titanium dioxide upon their surface (hereinafter called Catalytic Power) requires that the process be made volume efficient, and thus cost efficient. To do so, washing steps can be modified from a single step into several steps of smaller charges with intermediate filtering. The main point is to wash the slurry to remove salts and other contaminants. This can be broken into smaller washings as necessary.
[0194] Filtering the material from the 6 M HCl creates 2 potential problems: The first is to find large-scale corrosion resistant filtering equipment with the necessary personal safety considerations. The second is how to handle the waste stream. Typically, in industrial processes, waste streams are neutralized before going down the sewer so when it hits the waste treatment plant, they have only small pH adjustments to make and it has minimal impact on the “bugs”.
[0195] To address this problem, an alternative to filtering is to use a settling tank wherein settled material is drawn from the bottom of the tank. The time for settling is variously between 12 hours and 36 hours, and most often overnight. It is also possible to reuse a portion of the HCl (perhaps 50-90% of it) to reduce the waste stream.
[0196] Additionally, in order to minimize the time on the HCl filtration step (where the small particle size leads to long filtration times), one could use an idea analogous to affinity chromatography. One fills a column with glass beads and pours the acidic suspension of titania down through it. For small enough beads and a long enough column, the titania would filter out and stick to the beads. A pressure gradient through the column would assist the separation. Once the liquid has passed through, the beads would then be emptied into a container and tumbled with water to create the desired sol. The beads would then be removed through a coarse filter, left to dry, and then reused for the next separation. The column itself could be coated with teflon to minimize sticking of titania.
[0197] It has been found that dilute sols (around 1% TiO 2 ) lead to greater photocatalytic activity on the coated silica than more concentrated sols (around 2.3% TiO 2 ). The trade off is in manufacturing cost (the amount of waste water generated). A variant of this method adds a dispersant to the acidic titania sol in order to improve the distribution of the nanoparticulates on the core particles. Indeed, the reason the more dilute sols seem to increase photocatalytic activity (see the next section 2.) may be due to better distribution of the nanoparticulates on the core particles.
[0198] The desired % of water in the final filter cake (5% TiO 2 on Silica) prior to drying is typically 30%+−7%. The variance is caused by variability in filtration times and pressure gradient across the filter media: more filtration time or greater gradient makes the cake drier, less filtration time or less gradient, wetter. Less moisture is desirable to minimize energy costs from drying.
[0199] The annealing phase of the process may also be optimized for economic benefit. Annealing time need be no longer, and temperature no higher, than required to achieve satisfactory photocatalytic activity in the finished Catalytic Powders.
[0200] 2. Composite Photocatalytic Particles
[0201] It will be recalled that the present invention has separate, and severable, aspects relating to composite photocatalytic particles comprised of a particle core with substantially discrete photocatalytic particles dispersed onto the surface of the particle core. Suitable core particles include silicate and carbonate sands and powders, inorganic pigments, mineral and mineral composites, construction aggregates including roofing granules, polymeric granules and mixtures thereof. The photocatalytic particles have an average diameter size within the range of about 1 nm to 100 nm and are dispersed on the surfaces of the core particles in an amount of less than 20 wt. % based on total particle weight. The scope of the present invention also includes building materials containing these composite photocatalytic particles and processes for making these composite particles.
[0202] 2.1 Preparation of Composite Photocatalytic Particles
[0203] The core particles used to make the composite photocatalytic particles of the present invention can be varied. They may be rounded, polyhedral, or irregular shaped and produced through mining, crushing of aggregates, or a manufacturing process for making polymeric granules or composite polymeric and mineral-based granules, such as roofing granules. Preferably, the core particles do not interfere with the photocatalytic action of the composite particle and do not adversely interact with other components in an end-use application. One important aspect is the size of the core particle. It is desirable that the core particle be larger than the photocatalyst particles. Typically, the average size of the core particle is within the range of 100 nanometers to 1 centimeter in diameter, the size being determined by the end-use of the composite photocatalytic particle.
[0204] Examples of core particles include, but are not limited to polymer granules and powders such as: acrylics, acrylonitriles, acrylamides, butenes, epoxies, fluoropolymers, melamines, methacrylates, nylons, phenolics, polyamids, polyamines, polyesters, polyethylenes, polypropylenes, polysulfides, polyurethanes, silicones, styrenes, terephthalates, vinyls; and inorganic particles of the following, including those in hydrated form: oxides of silicon, titanium, zirconium, zinc, magnesium, tungsten, iron, aluminum, yttrium, antimony, cerium, and tin; sulfates of barium and calcium; sulfides of zinc; carbonates of zinc, calcium, magnesium, lead and mixed metals, such as naturally occurring dolomite which is a carbonate of calcium and magnesium, CaMg(CO 3 ) 2 ; nitrides of aluminum; phosphates of aluminum, calcium, magnesium, zinc, and cerium; titanates of magnesium, calcium, strontium, and aluminum; fluorides of magnesium and calcium; silicates of zinc, zirconium, calcium, barium, magnesium, mixed alkaline earths and naturally occurring silicate minerals and the like; aluminosilicates of alkali and alkaline earths, and naturally occurring aluminosilicates and the like; aluminates of zinc, calcium, magnesium, and mixed alkaline earths; hydroxides of aluminum, diamond; feldspars; or the like and above mixtures or composites thereof. As used herein, mixtures refer to a physical mixture of core particles containing more than one type of particulate form. As used herein, composites refer to intimate combinations of two or more core materials in a single particle, such as an alloy, or any other combination wherein at least two distinct materials are present in an aggregate particle.
[0205] The photocatalyst particles used to make the composite particles of this invention can be varied. Typically, the average size of the photocatalyst particle is within the range of 1 nanometer to 100 nanometers, preferably about 1 nanometer to 50 nanometers, and more preferably about 1 nanometers to 10 nanometers. In accordance with the present invention, the photocatalyst particles form a noncontinuous coating of a discrete particulate form and can be observed and measured by electron microscopy such as transmission electron microscopy.
[0206] The photocatalytic particles used to coat the surfaces of the core particles include one or a combination of two or more of known metal compound semiconductors such as titanium oxides, zinc oxides, tungsten oxides, iron oxides, strontium titanates, and the like. Particularly titanium oxides which have a high photocatalytic function, a high chemical stability and no toxicity is preferred. In addition, it is preferred to include inside said photocatalyst particles and/or on the surfaces thereof at least one metal and/or a compound thereof selected from the group consisting of V, Fe, Co, Ni, Cu, Zn, Ru, Rh, Si, Sn, Pd, Ag, Pt and Au as a second component because of the higher photocatalytic function of the resulting photocatalyst particles. The aforementioned metal compounds include, for example, metal oxides, hydroxides, oxyhydroxides, sulfates, halides, nitrates, and even metal ions. The content of the second component may vary depending upon the kind thereof. Preferred photocatalyst particles which may contain the aforementioned metals and/or metal compounds are of titanium oxide.
[0207] Preferred photocatalyst particles are anatase titanium dioxide, zinc oxide, tungsten trioxide, and the above mixtures or composites thereof. More preferred photocatalyst particles are mixtures, composites, or alloys of the above oxides with silica dioxides and tin oxides.
[0208] The amount and size of photocatalyst particles will influence the surface area and thus impact the oil absorption of the final composite particle, as described hereinbelow. For example, larger size photocatalyst particles within the above prescribed ranges and/or fewer photocatalyst particles can be used to minimize oil absorption. Typically, the amount of photocatalyst particles is less than about 20 weight %, based on the total weight of the composite particle, preferably less than about 10 weight %, and more preferably less than about 6 weight %. The shape of the photocatalyst particles can be spherical, equiaxial, rod-like or platelet. Preferably, the photocatalytic particle is equiaxial or spherical to minimize oil absorption.
[0209] It is desirable to have a substantially uniform distribution of the photocatalyst particles on the surfaces of the core particles. The photocatalyst particles will be attracted to the core particle surfaces by van der Waals' forces and may be further anchored to the core particle surfaces by chemical bonding and/or by hydrous oxide bridges, if hydrous oxides are present on the core particles as a topcoat.
[0210] Aggregates or agglomerates of photocatalyst particles are preferably broken down to primary particles to maximize surface area of the photocatalyst and minimize the amount of photocatalyst used. Aggregates are distinguished from agglomerates in that aggregates are held together by strong bonds such as fusion bonds and cannot be fragmented easily, while agglomerates are weakly bonded and can be broken up by high energy agitation.
[0211] The composite photocatalyst particles of this invention can be prepared by a variety of processes. In one process, an aqueous slurry of core particles is prepared. A colloidal suspension of photocatalyst particles, i.e., a sol is added to the aqueous core particle slurry with sufficient mixing. Mixing can be carried out by any suitable means at a ratio of core particles to photocatalytic particles which achieves the desired weight % of discrete particles in the final composite particle product. “Sol” is defined herein as a stable dispersion of colloidal particles in a liquid containing about 0.1 to 60% by weight photocatalyst particles as a dispersion in a liquid typically water. “Colloidal” is used herein to refer to a suspension of small particles which are substantially individual or monomeric particles and small enough that they do not settle. For purposes of this invention, it is important that the average size of the photocatalytic particles in the colloidal suspension (i.e., sol) be within the range of about 1 to about 100 nm (0.001-0.1 microns) in diameter, preferably about 1 to about 50 nm (0.001-0.05 microns), and more preferably about 1 to about 50 nm (0.001-0.01 microns). These photocatalytic particles sizes are generally the same sizes in the final composite particle product. It is preferred that the colloidal suspension be at the highest solids concentration at which the suspension is stable, typically about 14 to 50 wt. % solids. These colloidal suspensions (sols) can be prepared as known in the art, such as described in Yasuyuki Hamasaki's “Photoelectrochemical Properties of Anatase and Rutile Films Prepared by the Sol-Gel Method,” 1994, J. Electrochem. Soc. Vol. 141, No. 3 pp 660-663 and Byung-Kwan Kim's “Preparation of TiO2-SiO2 powder by modified sol-gel method and their photocatalytic activities,” 1996, Kongop Hwahak, 7(6), pp 1034-1042.
[0212] It has been found that both the particles in the core particle slurry and the photocatalyst particles in the colloidal suspension should be preferably both above or both below their respective isoelectric points to achieve a substantially uniform surface coating. The “isoelectric point” is used herein to refer to the pH at which particles have a neutral net charge. The core particles in the slurry and the photocatalyst particles in the colloidal suspension may also have opposite charges. Additionally, if the mixture of core particle slurry and colloidal photocatalyst particles have low ionic strength and the pH is such that both the core particles and the photocatalyst particles are both above or below their isoelectric points, then it is useful to adjust the pH of the mixture so that either the core particles or the photocatalyst particles approach their respective isoelectric points. This additional pH adjustment will generally be necessary whenever the ionic strength of the mixture is low.
[0213] Alternatively, core particles may be combined with a reaction mixture which is a precursor for forming a colloidal suspension of photocatalyst particles. The nano-size photocatalyst particles are then formed in the presence of the core particles and deposit onto the core particles. For example, reference U.S. Pat. No. 5,840,111 wherein a precursor solution comprising sulfuric acid and titanyl sulfate is combined at elevated temperature to an alkaline-reacting liquid until the resultant mixture reacts acidically and forms titanium dioxide nanoparticles.
[0214] Optionally, photocatalyst particles may be adhered to the core particle by a hydrous oxide bridge. Such hydrous oxides are silica, alumina, zirconia, and the like. In this process, a dry mix of core particles containing one or more soluble forms of silica, alumina, zirconia, and the like, such as sodium silicate, potassium silicate and sodium aluminate, are combined with an acidic colloidal suspension of photocatalyst. Suitable acids include HCl, H 2 SO 4 , HNO 3 , H 3 PO 4 or the like. Alternatively, an alkali colloidal suspension of photocatalyst may be used in which case the core particles contain aluminum sulfate, aluminum chloride or other alkali-neutralized soluble forms of silica, alumina, zirconia, and the like. Suitable bases include NaOH and KOH. Core particles are added to the colloidal suspension with high shear mixing. In carrying out the mixing, a high shear mixer such as a Waring blender, homogenizer, serrated disc type agitator or the like can be used. Specific speed characteristics depend on equipment, blade configuration, size, etc., but can be determined readily by one skilled in the art. The total solids content (i.e., core and photocatalyst particles) of the resulting slurry is above about 25% by weight, and above 50% by weight is preferred. The resulting slurry is then dried.
[0215] Optionally, photocatalyst particles may be adhered to the core particle by a calcium oxide bridge. In this process, a dry mix of core particles containing Portland cement, or other similar cement, in the particle is combined with an acidic colloidal suspension of photocatalyst. Mixing may be accomplished with a rotary cement mixer as used by building contractors in the field. The total solids content (i.e., core and photocatalyst particles) of the resulting slurry is above about 25% by weight, and above 50% by weight is preferred. The resulting slurry may then be dried or used directly as the wet aggregate component for addition to cement or concrete mixes as known in the art.
[0216] An alternative method of carrying out the invention is forming an aqueous mixture by combining water with the colloidal suspension of photocatalyst particles as described above in the presence of at least one dispersant. The dispersant can be either added simultaneously with the water or subsequently to the addition of photocatalyst particles. The dispersant can be selected from those described in U.S. Pat. No. 5,393,510, the teachings of which are incorporated herein by reference. Examples of dispersants include alcohol amines such as 2-amino-2-methyl-1-propanol, 2,2′,2″-nitrilotrisethanol, 2,2′-iminobisethanol, 2-aminoethanol and the like, and 1-amino-2-propanol, polyacrylates, citric acid and tetrapotassium pyrophosphate (TKPP) and the like. Typically a combination of the above dispersants is preferred in an amount of about 0.05 to about 5% based on the core particle weight. The concentration of photocatalyst particles in the colloidal suspension is from about 0.1 to 60 weight % preferably about 14 to 50 wt %. It is preferable that the photocatalyst colloidal particles be well dispersed and not in an aggregate or flocculated form. As described above, both positive or both negative charges of the photocatalyst particles in the colloidal suspension and the core particles are preferred to achieve a substantially uniform surface coating. Core particles are added to this aqueous mixture with high shear mixing as described above. The total solids content (i.e., core and photocatalyst particles) of the resulting slurry is above about 25% by weight, and above 500 by weight is preferred.
[0217] The conventional finishing steps such as filtering, washing, and drying the composite photocatalyst particles are known and are subsequently carried out. The resulting product is a dry, finished composite photocatalyst particle which is useful for end-use applications and/or can be used to prepare a slurry useful for end-use applications. For example, slurries of silica or carbonate sands coated with photocatalyst particles can be combined with Portland cement, or other similar cement, for preparing stucco as known in the art.
[0218] The resulting composite photocatalyst particles of this invention are suitable for use as aggregates and fillers for creating microbe-resistant building products. For example, building products that may use composite particles of this invention include stucco, precast concrete, structural cement, swimming pool cement, cementatious coatings, grout, roofing shingles, textured and abrasion resistant coatings, and other building products. The enhanced microbe resistance is demonstrated under conditions where light is present.
[0219] To give a clearer understanding of the invention, the following Examples are construed as illustrative and not limitative of the underlying principles of the invention in any way whatsoever.
[0220] 2.2 First Example of A Composite Photocatalytic Particle
[0221] A pure strain of green algae was inoculated into liquid growth media with 5% by weight 1.4 micron average diameter silica powder (the control) and also into identical media mixed with 5% by weight silica powder coated with 5% by weight nanoparticulate anatase titanium dioxide. The composite photocatalytic particle was prepared using the method detailed in Comparative Example 1.2. The mixtures were placed in two stirred flasks and exposed for three days under cool white fluorescent light at 450 foot-candles. The amount of algae growth in each flask was then measured using absorbance normalized at 480 nm. Normalized on a 0 to 1 scale, absorbance at 480 nm averaged 0.08 for the media containing photocatalytic powder verses 1 for the media containing regular powder.
[0222] A bar chart illustrating the algae-inhibiting effect of photoactive antifouling aggregate comprising 25 weight % non-colloidal photoactive zinc oxide and 75 weight % colloidal anatase titanium dioxide is shown in FIG. 5.
[0223] A bar chart showing the inhibiting effect of an the aggregate of FIG. 5 on the growth of E. coli bacteria is shown in FIG. 6.
[0224] 2.3 Second Example of A Composite Photocatalytic Particle
[0225] [0225] E. coli was inoculated onto a polyester resin coating mixed with 20% by weight solids 1.4 micron average diameter silica powder (the control) and also onto an identical coating mixed with 20% by weight solids silica powder prepared as in Comparative Example 2.2. After twenty-four hours of exposure under cool white fluorescent light at 450 foot-candles, the polyester films were imprinted onto agar plates and the agar left to colonize over 12 hours. The number of colonies that grew on the agar plates were then counted. Normalized on a 0 to 1 scale, the number of E. coli colonies observed averaged 0.03 for the treated polyester resin versus 1 for the untreated resin.
[0226] 3.0 Photocatalytic Aggregates
[0227] The extender particles used to make the composite aggregate particles of this invention can be varied. They may be rounded, polyhedral, or irregular shaped and produced through mining, grinding of minerals, or synthetic methods. Preferably, the extender particles do not interfere with the photocatalytic action of the composite aggregate and do not adversely interact with other components in an end-use application. One important aspect is the size of the extender particle. It is desirable that the extender particle have an average size of 100 nanometers to 1 centimeter and that the extender particle be larger than the photocatalyst particles.
[0228] Examples of extender particles include, but are not limited to inorganic particles of the following, including those in hydrated form: oxides of silicon, titanium, zirconium, zinc, magnesium, tungsten, iron, aluminum, yttrium, antimony, cerium, and tin; sulfates of barium and calcium; sulfides of zinc; carbonates of zinc, calcium, magnesium, lead and mixed metals, such as naturally occurring dolomite which is a carbonate of calcium and magnesium, CaMg (CO 3 ) 2 ; nitrides of aluminum; phosphates of aluminum, calcium, magnesium, zinc, and cerium; titanates of magnesium, strontium, calcium, and aluminum; fluorides of magnesium and calcium; silicates of zinc, zirconium, calcium, barium, magnesium, mixed alkaline earths and naturally occurring silicate minerals and the like; aluminosilicates of alkali and alkaline earths, and naturally occurring aluminosilicates and the like; aluminates of zinc, calcium, magnesium, and mixed alkaline earths; hydroxides of aluminum, diamond; feldspars; natural and synthetic clays; wollastonite; or the like and above mixtures or composites thereof. As used herein, mixtures refer to a physical mixture of extender particles containing more than one type of extender material form. As used herein, composites refer to intimate combinations of two or more extender materials in a single extender particle, such as an alloy, or any other combination wherein at least two distinct materials are present in an aggregate extender particle.
[0229] The photocatalytic titanium oxide is exposed on the surface of the extender particle in the form of discrete particles. The discrete particles may form small agglomerates, such as flocculated particles, on the surface of the aggregate particle, but this is less desirable because some discrete particles will then be shaded. The discrete particles typically have an average size within the range of 1 nanometer to 100 nanometers, preferably about 1 nanometers to 50 nanometers, and more preferably about 1 nanometers to 10 nanometers. The discrete particles can be observed and measured by electron microscopy such as scanning electron microscopy.
[0230] The photocatalyst used to make the composite aggregate particles of this invention are titanium oxides which have a high photocatalytic function, a high chemical stability and no toxicity. More particularly preferred is the anatase crystalline form of titanium dioxide.
[0231] It is desirable to have a substantially uniform, although not necessarily continuous, distribution of discrete photocatalyst particles on the surfaces of the aggregate particles. Typically, the amount of photocatalyst is less than 20 weight % based on the total weight of the aggregate material, preferably less than 10 weight %, and more preferably less than 6 weight %.
[0232] The photocatalyst material will be attracted to the extender particle surfaces by van der Waals' forces and may be further anchored to the extender material surfaces by stronger chemical bonds such as fusion bonds. It has been found that flocculation of photocatalyst particles reduces photocatalytic efficiency, likely due to optical crowding effects, and is generally undesirable.
[0233] The aggregates of this invention generally disperse easily in aqueous and solvent-based slurries, coatings, and solutions. Unlike virgin photocatalyst, dispersion does not generally require the use of chemical dispersing aides or aggressive agitation or milling.
[0234] 3.1 Preparation of Photoactive Antifoulant Aggregates
[0235] The photoactive antifoulant aggregates of this invention can be prepared by a variety of processes. In one process, an aqueous slurry of extender particles is prepared. To this slurry is added, with sufficient mixing, a colloidal suspension, i.e. a sol, of titanium oxide particles. Mixing can be carried out by any suitable means at a ratio of extender particles to photocatalytic particles which achieves the desired weight % of premium photocatalyst in the final aggregate. “Sol” is defined herein as a stable dispersion of colloidal particles in a liquid containing about 0.1 to 60% by weight particles as a dispersion in a liquid typically water. “Colloidal” is used herein to refer to a suspension of small particles which are substantially individual or monomeric particles and small enough that they do not settle. The photocatalyst particle sizes are generally the same sizes at the start of the process as in the final aggregate particle product. It is preferred that the colloidal suspensions of photocatalyst be at the highest solids concentration at which the suspension is stable, typically about 14 to 50 weight % solids. These colloidal suspensions (sols) can be prepared as known-in the art, such as described in U.S. Pat. No. 5,840,111; Yasuyuki Hamasaki's “Photoelectrochemical properties of anatase and rutile films prepared by the sol-gel method,” 1994 , J. Electrochem. Soc . Vol. 141, No. 3 pp 660-663; and/or Byung-Kwan Kim's “Preparation of TiO2-SiO2 powder by modified sol-gel method and their photocatalytic activities,” 1996 , Kongop Hwahak, 7(6), pp 1034-1042.
[0236] It has been found that the particles in the extender particle slurry and the photocatalyst particles in the colloidal suspension should both be preferably above or below their respective isoelectric points to achieve a substantially uniform surface coating of the smaller colloidal particles on the larger slurry particles. The “isoelectric point” is used herein to refer to the pH at which particles have a neutral net charge. The particles in slurry form and the particles in colloidal suspension may also have opposite charges. Additionally, if the mixture of slurry and colloidal particles have low ionic strength and the pH is such that the extender particles and photocatalyst particles are both above or below their isoelectric points, then it is useful to adjust the pH of the mixture so that one of the particles approaches its isoelectric point. This additional pH adjustment will generally be necessary whenever the ionic strength of the mixture is low.
[0237] In applications in which acid excesses have a disruptive effect, the colloidal suspensions according to the invention may subsequently be stabilized in the neutral pH range in a manner known in principle, for example with acetylacetone (see, e.g., WO-93/05875) or with hydroxycarboxylic acids (see, e.g., EP-A518 175).
[0238] In an alternative preparation process, extender particles may be added to a solution containing a soluble form of a titanium oxide precursor and then an acid or base added to reactively coat the extender particles in situ with discrete photocatalyst particles to make the aggregate particles of this invention. For example, in U.S. Pat. No. 5,840,111 Wiederhoft describes a precursor solution comprising sulfuric acid and titanyl sulfate. Extender particles may be added to this precursor solution and then an alkaline-reacting liquid added, with sufficient mixing, until the resultant mixture reacts acidically and forms a coating of discrete titanium dioxide particles on the extender particles.
[0239] The conventional finishing steps such as filtering, washing, drying and grinding the aggregate antifouling product are known and are subsequently carried out. The resulting product is a dry, finished aggregate photocatalyst particle which is useful for end-use applications and/or can be used to prepare a slurry useful for end-use applications. Methods of preparing particulate slurries are known in the art, for example, as described in Canadian Patent 935,255.
[0240] Alternatively, titanium oxide particles may be adhered to the extender particle by stronger chemical bonds such as fusion bonds. In one embodiment of this process, a dry mix of extender particles containing one or more soluble forms of silica, alumina, zirconia, and the like, such as sodium silicate, potassium silicate and sodium aluminate, are combined with an acidic colloidal suspension of photocatalyst, such as the titania sol described earlier. Suitable acids include HCl, H 2 SO 4 , HNO 3 , H 3 PO 4 or the like. Alternatively, a basic colloidal suspension of photocatalyst may be used in which case the extender particles contain aluminum sulfate, aluminum chloride or other base neutralized soluble forms of silica, alumina, zirconia, and the like. Suitable bases include NaOH and KOH. Extender particles are added to the colloidal suspension with sufficient mixing. The total solids content (i.e., extender and titanium oxide particles) of the resulting slurry is above about 25% by weight, and above 50% by weight is preferred.
[0241] An alternative method of carrying out the invention is forming an aqueous mixture by combining water with the colloidal suspension of titanium oxide in the presence of at least one dispersant. The dispersant can be either added simultaneously with the water or subsequently to the addition of titanium oxide particles. The dispersant can be selected from those described in U.S. Pat. No. 5,393,510, the teachings of which are incorporated herein by reference. Examples of dispersants include alcohol amines such as 2-amino-2-methyl-1-propanol, 2,2′,2″-nitrilotrisethanol, 2,2′-iminobisethanol, 2-aminoethanol and the like, and 1-amino-2-propanol, polyacrylates, citric acid and tetrapotassium pyrophosphate (TKPP) and the like. Typically a combination of the above dispersants is preferred in an amount of about 0.05 to about 5% based on the aggregate particle weight. The concentration of particles in colloidal suspension is from about 0.1 to 60 weight %, preferably about 14 to 50 weight %, and in slurry form above 25 weight %, and above 50 weight % preferred. It is preferable that the particles be well dispersed and not in an aggregate or flocculated form. As described above, all positive or all negative charges of the titanium oxide particles and the extender particles are preferred to achieve a substantially uniform surface coating. Extender particles are added to this aqueous mixture with high shear mixing or milling as described in greater detail in Canadian Patent 935,255, U.S. Pat. Nos. 3,702,773 and 4,177,081, the teachings of which U.S. patents are incorporated herein by reference. In carrying out the mixing, a high shear mixer or mill such as a Waring™ blender, homogenizer, serrated disc type agitator, ball mill, sand mill, disc mill, pearl mill, high speed impeller mill or the like can be used. (Waring™ is a registered trademark of the Waring Corporation.) Specific speed characteristics depend on equipment, blade configuration, size, etc., but can be determined readily by one skilled in the art. The total solids content (i.e., extender and photocatalyst particles) of the resulting slurry is above about 25% by weight, and above 50% by weight is preferred.
[0242] 3.2 Action of the Antifouling Aggregates So Produced
[0243] The resulting improved photoactive antifoulant aggregate products of this invention are suitable for use in coatings and building products, for example, in antifoulant coatings, stucco, swimming pool cement, grout, concrete, wall shingles, hard flooring, and roofing granules. The antifouling activity is best demonstrated in products where the surface concentration of exposed photoactive aggregate is greater than 1%, preferably greater than 5%, and more preferably greater than 10%. Surface concentration is expressed as a percentage and represents the volume of the photoactive aggregate at the active surface divided by the sum of the volumes of the photoactive aggregate at the active surface and the carrier at the active surface. Antifouling activity is observed only when U.V. or visible light is present to expose the photoactive aggregate. Photoactive aggregate present in the body of the coating or building product but not exposed at the surface does not contribute to antifouling activity. Polymeric binders subject to photocatalytic attack, such as acrylic and polyester resin, chalk over time from contact with the photoactive aggregates of this invention in the presence of U.V. or visible light. Photocatalytic chalking from photoactive pigments is well known in the painting industry, and such chalking exposes pigment particles in the paint. In the present invention, chalking exposes more antifouling aggregate and thus improves the antifouling activity of the coating. Where chalking is undesirable in the coating, alternative resins may be employed such as silicones and fluoropolymers as described in further detail in U.S. Pat. Nos. 5,547,823 and 5,616,532, the teachings of which are incorporated herein by reference.
[0244] In accordance with the preceding explanation, variations and adaptations of the method of producing and of using a nanoparticulate titanium dioxide coating in accordance with the present invention will suggest themselves to a practitioner of the chemical arts.
[0245] In accordance with these and other possible variations and adaptations of the present invention, the scope of the invention should be determined in accordance with the following claims, only, and not solely in accordance with that embodiment within which the invention has been taught.
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Nanoparticulate titanium dioxide coating produced by educing flocculates of titanium dioxide nanoparticles from a titanyl sulfate solution and dispersing the nanoparticles in a polar sol-forming medium to make a sol suitable as a coating usable to impart photocatalytic activity, U.V. screening properties, and fire retardency to particles and to surfaces. The photocatalytic material and activity is preferably localized in dispersed concentrated nanoparticles, spots or islands both to save costs and leverage anti-microbial effects.
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BACKGROUND AND SUMMARY OF THE INVENTION
[0001] The present invention relates to a vehicle brake system and, more specifically, to vehicle speed determination portion.
[0002] Modern road and rail vehicles are normally equipped with an antilock system which, in the case of road vehicles, is called an “ABS system,” and, in the case of rail vehicles, is called a “nonskid system.” ABS systems and nonskid systems have the purpose of controlling the brake pressures at individual wheels or axles of the vehicle such that a locking of the wheels or wheel sets is prevented, and the braking distance is minimized. For this type of a brake pressure control, the amount of slip at the individual wheels or axles are required which are determined from the respective wheel speeds and the actual vehicle speed. For this purpose, rotational wheel speed sensors are normally required, and an approximated value for the actual vehicle speed is computed from the individual rotational wheel speeds. This value will be called the “reference speed” in the following.
[0003] Particularly in the case of poor coefficients of adhesion between the wheel and the roadway/track, the reference speed significantly influences the brake power control at the wheels. A “false” reference speed can, therefore, result in errors in the brake power control of the entire vehicle. Thus, for a good ABS or nonskid system control, a determination of the actual vehicle speed, that is, of the reference speed, is required which is as exact as possible. Particularly in the case of vehicles which only have a single independent system for the brake power control, in the event of a reduced coefficient of adhesion between the wheel and the rail, a protection must be ensured against individual errors.
[0004] From German Patent Document DE 39 31 313 A1, an antilock system for a motorcycle is known in which one rotational speed sensor respectively is assigned to the front wheel and the rear wheel. For determining the wheel slips, a reference speed which approximates the actual vehicle speed is determined for the front wheel and the rear wheel respectively.
[0005] The ABS and nonskid systems each conventionally have a single-channel construction, that is, the rotational wheel speed is sensed for each wheel or wheel group respectively by a single rotational wheel speed sensor. When a pulse generator, that is, a rotational wheel speed sensor fails, the assigned wheel or wheels is/are “unprotected,” that is, they can no longer be controlled corresponding to the rotational wheel speed.
[0006] If a defective rotational wheel speed sensor supplies a “false” wheel speed which is used to determine the reference speed, there is the risk that the brake pressure is erroneously reduced on all axles or that the traction is regulated in a faulty manner or is regulated down on all axles.
[0007] So that faulty rotational wheel speed signals, if possible, will not falsify the reference speed value, algorithms for computing the reference speed known from prior art originating from the applicant have a “detection” of faulty signals, but a reliable detection of all possible faults requires very high expenditures. In addition, already during the “fault disclosure time,” faults can have such an effect on the computation of the reference speed that the brake power control is disadvantageously affected.
[0008] It is an object of the invention to provide a brake system which is optimized with respect to the determination of the actual vehicle or reference speed and, also in the event of a sensor, leaves no wheel unprotected. This object is achieved by the present system.
[0009] In the case of a brake system having an electronic brake unit and rotational wheel speed sensors connected thereto, the basic principle of the invention consists of assigning to each wheel to be monitored and to each wheel group to be monitored at least two wheel sensors respectively. During the operation, all wheel sensors present in the vehicle are constantly monitored. However, the reference speed approximating the actual vehicle speed is determined at any point in time using only one of the rotational wheel speed signals sensed by the wheel sensors. Which of the existing rotational wheel speed sensors should instantaneously be selected and considered decisive for the reference speed is determined according to the invention as a function of the actual driving condition and at least one defined speed criterion. The invention, therefore, provides an ABS or nonskid system with a fault tolerance against a failure of a speed sensor.
[0010] In simplified terms, the system examines whether the vehicle is just being braked or accelerated or is coasting without being driven. As a function of the present driving condition, one of the “higher” measured or of the “lower” measured wheel speeds is used as the basis for determining the reference speed, which will be explained in greater detail.
[0011] According to a further development of the invention, in the case of a braked vehicle, the reference speed is determined according to the second-highest wheel speed. As an alternative, it can also be provided that, in the case of a braked vehicle, the minimum speed is determined first from each “rotational speed pair” of the mutually assigned rotational wheel speed sensors. The reference speed will then be determined according to the instantaneous maximum of these minimum speeds.
[0012] In the case of an unbraked vehicle, particularly in the case of a driven vehicle (traction), the reference speed can be determined according to the second-lowest wheel speed. As an alternative, it can be provided that, in the case of an unbraked vehicle, the maximum speed is first determined from each rotational speed pair, and that the reference speed will then be determined according to the minimum of these maximum speeds.
[0013] It is, therefore, ensured during the braking that a disturbance-caused excessive speed signal does not influence the reference speed. Correspondingly, in the case of an unbraked vehicle or in the “traction” condition, a disturbance-caused wheel speed signal which is too low is “blinded out” or filtered out.
[0014] The detection of the rotational wheel speed signals can take place either by a single control unit or, as an alternative, can be distributed on several control units when, for example, the number of available inputs of a control unit is not sufficient. In the case of a distribution on several control units, the wheel speed signals are mutually exchanged between the control units by a data bus.
[0015] Since, according to the invention, two rotational wheel speed sensors are assigned to a wheel or a wheel group respectively, it must also be determined which of the two rotational wheel speed sensors is to be decisive for the brake power control, that is, the ABS or nonskid system respectively and the ASR control at the respective wheel or the respective wheel group. First, when considering the ABS and nonskid control respectively, the following may be provided:
[0016] a) The ABS and nonskid control, respectively, are based on the higher wheel speed of the wheel speeds supplied by the mutually assigned wheel sensors, specifically when, in a driving condition, the “protection against an erroneous releasing of the brake” has the highest priority, for example, in the case of a single-driving vehicle; or
[0017] b) the ABS or nonskid control, respectively, is based on the lower wheel speed of the two wheel speeds when “the antilock protection” has the highest priority, for example, in the case of a train consisting of several cars.
[0018] With respect to the wheel slip control system (ASR or antislip control) of a wheel, the following can be provided:
[0019] a) The ASR control is based on the lower of the two wheel speeds when the “protection against an erroneous reduction of the traction force” has the highest priority; or
[0020] b) the ASR control is based on the higher of the two wheel speeds when the spin of a wheel is to be prevented with the highest priority.
[0021] According to a further development of the invention, all rotational wheel speed signals are subjected to a plausibility check by an electronic monitoring unit. When a fault is detected for a rotational wheel speed signal or when a rotational wheel speed signal is considered implausible, which can be caused, for example, by a sensor failure or by sensor signal peaks because of external electromagnetic interference fields, after a corresponding “fault disclosure time” (time duration until the fault is detected), this rotational wheel speed signal is no longer included in the determination of the reference speed and also no longer into the controlling of the braking or driving force of the assigned wheel or wheel group. In such a case, only the second “channel,” that is, the other assigned rotational wheel speed sensor, is still analyzed.
[0022] The invention is, therefore, based on the assumption that not the electronic unit but the “periphery,” that is, particularly the sensor system, represents the main fault source. The reason is that sensors fail considerably more frequently than the electronic brake unit itself. In contrast to the abovementioned German Patent Document DE 39 31 313 A1, the invention moves away from the “idea of the dual-channel characteristic of the reference speed,” according to which an “own” reference speed is defined for individual wheel and wheel groups respectively.
[0023] On the contrary, according to the invention, a “double,” that is, truly redundant, rotational speed detection is provided. An individual fault of a sensor, therefore, does not affect the entire brake control of the vehicle because, in addition to the faulty speed information, an intact speed information of the “affected” wheel or of the concerned wheel group is still present.
[0024] A central point of the invention in this case is the above-described “selection logic.” The selection logic permits a fast and simple decision as to which of the two mutually assigned sensors, for safety reasons or for availability reasons, supplies the “more precise or more realistic” signal. Thus, that sensor of a pair of sensors can be “separated out” very rapidly, that is, already during a fault recognition time, whose inclusion has an unfavorable effect on the control target; for example, whose inclusion into the reference speed would have a disadvantageous effect on the driving safety. An individual sensor cannot, therefore, influence the reference speed determination in such a manner that all or some of the vehicle brakes are erroneously “debraked.”
[0025] In particular, the individual brake pressure control of the wheel affected by an individual fault of a sensor can, as a rule, be implemented to an unlimited extent. If the faulty sensor can be determined, after the expiration of the fault recognition time, the intact sensor is automatically used which is always available here to the logic for this wheel, so that no losses have to be accepted with respect to the controllability. Before the expiration of the fault recognition time or in the case of faults where it cannot be decided which of the two differing sensors is faulty, corresponding to the above-explained criteria, a decision is made either in favor of the driving safety or in favor of the availability. In the case of a decision in favor of the driving safety, that sensor is considered to be “valid” which indicates the lower wheel slip, that is the lower braking. In the case of a decision in favor of the availability, that sensor is considered to be “valid” which indicates the higher wheel slip, that is, which indicates a greater braking of the wheel or wheel group.
[0026] In comparison to conventional brake systems, in which in each case only one rotational speed sensor is provided for determining the wheel speeds, the reference speed determination according to the invention is based on a larger number of sensor signals, which improves the protection against faults or the detectability of faults.
[0027] The advantages of the invention can be summarized as follows:
[0028] 1. An individual fault during the detection of the wheel speed will never affect the reference speed formation such that the braking force or a portion of the braking force of the vehicle or the driving force of the vehicle is completely reduced. This applies also when only one control unit is used.
[0029] 2. The possibilities for detecting implausible rotational wheel speed signals are significantly improved because the number of detected rotational wheel speeds is large, and the speeds can be centrally compared with one another.
[0030] 3. As a result of the redundant rotational speed detection, two rotational speed signals of a wheel can always be included in the control. The wheel, therefore, also remains protected when one of the two rotational speed signals fails.
[0031] 4. The “2-channel characteristic” can be implemented in a cost-effective manner by using only one control computer. In contrast to a single-channel system, only double pulse generators or two individual rotational speed generators are required. The use of two control units is not absolutely necessary.
[0032] Other aspects of the present invention will become apparent from the following detailed description of the invention, when considered in conjunction with accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] [0033]FIG. 1 is a schematic representation of a vehicle incorporating a brake system according to the principles of the present invention.
[0034] [0034]FIG. 2 is a simplified representation of the construction of the electronic brake unit according to the principles of the present invention.
[0035] [0035]FIG. 3 is a view of an embodiment of a 4-axle vehicle with axles which are independent with respect to the rotational speed with a brake system according to the principles of the present invention.
[0036] [0036]FIG. 4 is a view of another embodiment of a 4-axle vehicle with axles which are independent with respect to the rotational speed with a brake system according to the principles of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0037] [0037]FIG. 1 illustrates a rail vehicle 1 having a first bogie 2 and a second bogie 3 . The two vehicle axles 4 , 5 are assigned to the first bogie 2 , and the two vehicle axles 6 , 7 are assigned to the second bogie 3 . The wheel axle 4 is kinematically coupled with the wheel axle 5 , which is indicated here only by a schematically illustrated connecting rod. The wheel axles 4 , 5 , therefore, have the same actual rotational wheel speed. The same applies to the wheel axles 6 , 7 . The wheel axles 4 , 5 , as well as the wheel axles 6 , 7 , therefore, each form a “wheel group” with the same actual wheel speed.
[0038] The wheel speeds of the wheel axles 4 - 7 are sensed by assigned rotational wheel speed sensors 8 - 11 . The rotational wheel speed signals supplied by the rotational wheel speed sensors 8 - 11 are analyzed by a control unit 12 , which correspondingly controls the brakes of the bogies 2 and 3 .
[0039] In the case of a normal brake system, the rotational wheel speed sensors 8 , 9 and 10 , 11 , respectively, would supply identical signals. However, as a result of sensor interferences or external interfering influences, such as electromagnetic interfering fields, the sensor pairs 8 , 9 and 10 , 11 , respectively, may deviate from one another. As a function of the respective driving condition, that is, depending on whether the vehicle is braked or unbraked, by means of a speed criterion, a sensor which is to be considered valid can be selected from the sensor groups 8 , 9 and 10 , 11 , respectively.
[0040] In the case of a braked vehicle, for example, the reference speed can be determined on the basis of the rotational wheel speed sensor 8 - 11 which has the second-highest wheel speed. As an alternative, from each of the two sensor pairs 8 , 9 and 10 , 11 , respectively, the sensor with the minimal speed per pair can be selected. From the two minimal speed sensors, the maximal speed can then be selected for determining the reference speed (min-max selection).
[0041] In the case of an unbraked vehicle, the reference speed can be determined on the basis of the second-lowest wheel speed measured by the rotational wheel speed sensors 8 - 11 . As an alternative, first a maximal selection can be made from the two rotational speed pairs. Finally, from the two maximal speeds, the lower one can be used for determining the reference speed (max-min selection).
[0042] The brake pressure control at the wheel axles 4 - 7 can take place corresponding to the above-explained safety or availability criteria.
[0043] [0043]FIG. 2 is a simplified view of the algorithms implemented in a control unit according to the invention. The measured rotational speed signals v 1 are fed to three blocks, specifically, a plausibility control 13 , an algorithm 14 for computing the reference speed v ref , as well as a control algorithm 15 for controlling the driving/braking force z i of an individual wheel or of a wheel group.
[0044] The plausibility algorithm 13 makes a “rough selection.” In this case, it checks whether individual rotational wheel speed signals v 1 are not realistic at all and should, therefore, be separated out by providing signals to the reference speed algorithm 14 and control algorithm 15 .
[0045] A reference speed v ref is formed from the rotational wheel speed signals according to the above-explained driving condition and speed criteria. In this case, the reference speed computation v ref is always “oriented” or determined according to a single rotational wheel speed signal. “Orienting” means that the reference speed is not necessarily set to be identical with the instantaneously decisive rotational wheel speed signal but that the rotational wheel speed signal enters the reference speed possibly in a filtered or smoothed manner in order to obtain a “smooth” speed course or one that is as realistic as possible and which is approximated to the actual vehicle speed as well as possible.
[0046] Taking into account the rotational wheel speed signals v i and the reference speed v ref , the control algorithm 15 determines the wheel slips occurring at the individual wheels or wheel groups and, as a function thereof, controls the driving or braking forces by output signal z i .
[0047] [0047]FIG. 3 shows a schematic embodiment of the nonskid or antislip system of a 4-axle vehicle. In contrast to FIG. 1, the axles 4 - 7 are not mutually coupled with respect to the rotational speed. Each axle's speed is monitored by a pair of sensors. The rotational speed detection is distributed here to two “modules,” specifically to the control unit 12 and to an expansion module 16 which are connected with one another by a data bus 17 . This means a portion of the rotational wheel speed signals, for axles 4 and 7 , for example, is fed directly to the control unit 12 , and another portion of rotational wheel speed signals, for axles 5 and 6 , for example, is fed to the expansion module 16 . From the expansion module 16 , the rotational wheel speed signals are sent to the control unit 12 . However, the above-explained control algorithms are implemented in the control unit 12 .
[0048] [0048]FIG. 4 also shows an embodiment of a nonskid or antislip system for a 4-axle vehicle with independent axles. However, in contrast to FIG. 3, a separate control unit 12 , 12 ′ for the braking force control is assigned here to each of the two bogies 2 and 3 . In control unit 12 , rotational wheel speed signals v 1 , v 1′ , v 2 , v 2′ , are supplied, and in control unit 12 ′, rotational wheel speed signals v 3 , v 3′ , v 4 , v 4′ are supplied. Therefrom, brake control signals 18 to 21 for the axles 4 to 7 are computed by the control units 12 , 12 ′.
[0049] Although the present invention has been described and illustrated in detail, it is to be clearly understood that this is done by way of illustration and example only and is not to be taken by way of limitation. The spirit and scope of the present invention are to be limited only by the terms of the appended claims.
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For determining a reference speed which is approximated to the actual vehicle speed, at least two wheel sensors are provided for each wheel speed to be measured. All existing wheel sensors are analyzed, and only one is selected and used for determining the reference speed as a function of the actual driving condition and of at least one defined speed criterion. At least one sensor is always available for controlling each wheel, even if one sensor is faulty.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates in general to a constant flow fluid pump and in particular to means and method for reduction of pressure and flow pulsations in a fluid pump by selectively controlling the rotational speed of the pump driving motor at any one of a predetermined number of discrete rotational steps around the 360° periphery of the driving motor rotation.
2. Description of the Related Art
There are many applications for analyzing blood and other fluids for which it is important to move the fluid to be examined at a uniform rate through testing/analyzing equipment, such as a flow cytometer. These fluids are usually driven by a constant pressure source. However the application of a constant pressure to a fluid may not result in a constant flow if the resistance to flow changes. For constant flow, the force pumps for driving these fluids are either of the diaphragm or reciprocating piston type of positive displacement pump that is actuated by an electric motor.
A problem with positive displacement pumps is that the rotary displacement of the electric motor must be converted to a linear displacement in order to activate the pump and thereby pump the fluid, i.e., both the diaphragm and the reciprocating piston are driven by a powered rod of some type that receives its linear motion by means of a reciprocating crankshaft. Whether it be a diaphragm pump or a reciprocating piston pump, the linear actuated rod must have its power converted from the rotary motion of the motor by means of a crankshaft/driving rod arrangement. It is well known that the output of a rotary motor driving a rod through a crankshaft arrangement, has a sinusoidal displacement output. The driving rod experiences displacement variations ranging from a minimum of zero at both top dead center and bottom dead center of its rotation through the crankshaft journal to a maximum displacement midway between top dead center and bottom dead center. It is also well understood in the Art that other parameters of the output pump also experience the same sinusoidal variation through the 360° rotation of the driving motor through the crankshaft/driving rod arrangement. For example, it is well-known that the pressure and the flow output of both a diaphragm and a reciprocating piston pump consist of a half-rectified sine wave. If the pump is driving a purely resistive load, the pressure and flow will be in phase and have their maximum value when the crank of the pump is in the middle of its upstroke, at 90° away from top dead center (TDC). After the pump passes TDC, the flow and pressure go to zero for a purely resistive load until the crank reaches bottom dead center (BDC).
Positive displacement pumps of the leadscrew drive type can provide a constant flow independent of resistance. However they must be refilled during the downstroke, during which time there is no output flow. Dual acting positive displacement pumps of the leadscrew drive type operate in tandem, so that as one pump is supplying fluid, the other pump is refilling. However these types of double acting pumps are expensive and complex.
A flow cytometer requires a pulseless flow of sheath fluid to obtain precise particle measurements. Present flow cytometers, in order to compensate for the pressure/flow variation described above, use one of two methods known in the Art to apply a pulseless flow of sheath fluid. The first is the use of a pressurized tank of sheath fluid that will even out the pulsations and the second is the use of a compliant member such as for example compressing a static volume of air through a flexible membrane. The problems with these two compensation methods is that the tank must have a very small height to prevent pressure variations from occurring as the tank empties and the tank must be sturdy enough to withstand pressure of 5-10 PSI, and that a constant pressure source doesn't provide a constant flow if the resistance to flow changes. Furthermore, the sheath fluid becomes saturated with air, which may be released as micro bubbles at the flow cell, causing the detection of false particles. The second method is equally problematic in the use of flow cytometry as well as other fluids analytical instruments in that the compliant member often is large and unwieldy and sometimes several compliant members are necessary to smooth pulsations in the flow of sheath fluid. Accordingly, it would be desirable to have a fluid pump driven by an electric motor through a crankshaft/driving rod arrangement that would have as close to a constant pressure and fluid output as possible through the 360° rotational driving range of motion of the electric motor.
SUMMARY OF THE INVENTION
Briefly, the present invention is a means and method for controlling the output flow of a fluid pump. The invention does this by controlling the radial speed of the pump motor during discreet segments of the motor's 360° angular/radial path through a revolution of the pump. The electric pump motor is controlled throughout the 360° radial path by employing a control means for controlling the speed of actuation of the radial steps of a stepper motor throughout the 360° path of rotation of the stepper motor. Control means for controlling the speed of the discreet steps of the stepper motor comprises at least a memory means, a counting means and an amplification means. The memory means may be an EPROM or other memory device for storing a series of numbers, each number representing selective speeds for which the stepper motor rotates to desired positions. The counting means which may be for example a binary counter is for retrieving the discreet numbers from the memory means for each selective position speed. The amplifying means, which may be for example a bipolar constant current driver, takes the output control signal from the counting means and amplifies it and conditions it so that it is suitable for energizing the stepper motor to rotate at the selected discreet speed necessary to achieve the selected discreet position along the 360° rotation of the stepper motor output shaft.
The motor/pump combination of the invention provides a constant or near constant flow during the upstroke of the pump. Of course, every pump outputs no flow during the downstroke time. The constant flow motor/pump of the invention compensates for this by keeping the down stoke time to {fraction (1/30)} of the upstroke time and provides a flow interruption filter to suppress this interruption of the flow during the upstroke. This flow interruption filter includes two compliant lengths of tubing separated by a resistive orifice.
BRIEF DESCRIPTION OF DRAWINGS
The invention may be understood and further advantages and uses thereof more readily apparent, when considered in view of the following detailed description of the exemplary embodiments, taken with the accompanying drawings in which:
FIG. 1 is a graph of flow rate verses time for the prior art sinusoidal output of a rotary positive displacement pump driven by an electric motor;
FIG. 2 is a pictorial view of a rotary positive displacement pump driven by a stepper motor, constructed according to the teachings of the invention;
FIG. 2A is an enlarged top plan view of the reset sensing means with rotating flag shown in FIG. 1;
FIG. 3 is a block diagram of the control means for controlling the angular velocity/speed of the stepper motor of FIG. 2;
FIGS. 4A and 4B are a schematic view of the wiring diagram for the control means for controlling the angular velocity/speed of the stepper motor of FIG. 2;
FIG. 5 is a graph of the non-sinusoidal angular velocity (in half steps/second verses motor position in half steps) of the rotary positive displacement pump stepper motor constructed according to the teachings of the invention;
FIG. 6 is a graph of flow rate verses time of the rotary positive displacement pump driven by the stepper motor, all constructed according to the teachings of the invention;
FIG. 7 is a schematic drawing of the output filter apparatus that is placed in series with the output flow or the rotary positive displacement pump of the invention to minimize the flow interruption when the motor is turning the pump in the downstroke positions; and
FIG. 8 is a graph of flow rate verses time after the flow output from the rotary positive displacement pump of the invention passes through the filter apparatus of FIG. 7 .
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring now to the drawings and to FIG. 1 in particular there is shown a graph 10 of the prior art sinusoidal output of a rotary positive displacement pump driven by an electric motor. Both the pressure and volume output of the pump are shown as a half rectified sine wave, which graph replicates the actual output experienced by displacement pumps of the prior art.
Referring now to FIGS. 2 and 2A there are shown pictorial views of a rotary positive displacement pump unit 20 constructed according to the teachings of the invention. Pump unit 20 includes positive displacement pump 22 , mechanically coupled with and driven by stepper motor 24 , having mounting bracket 26 disposed there between. Stepper motor 24 is adapted for connection to outside electrical power by means of electrical connector 28 . Electrical power supplied to stepper motor 24 is conditioned by a control means of the invention so as to control the output of pump 22 to replicate as closely as possible a constant step function of both pressure and flow (volume per unit time). A full rotation of motor shaft 29 is sensed by sensing means 30 , which may be for instance an optical proximity sensor, when shaft flag 31 passes there through.
Referring now to FIG. 3 there is shown a block diagram 30 of the control means for controlling the angular velocity/speed of the stepper motor 24 of FIG. 2 through 400 half step output positions. Likewise referring now to FIGS. 4A and 4B there are shown a corresponding schematic view of the electronic circuit and wiring diagram for the control means for controlling the angular velocity/speed of the stepper motor of FIG. 2 . FIGS. 3 and 4 A,B have a one to one correspondence between their respective blocks in FIG. 3 and the directly corresponding individual electronic circuits shown in phantom boxes in FIGS. 4A and 4B. Block diagram 30 includes counter means 32 , memory means 34 , conversion means 36 , amplification means 38 and reset means 42 . Likewise electronic circuit and wiring diagram 50 includes counter means circuit 52 which corresponds directly with counter means block 32 of block diagram 30 ; memory means circuit 54 which corresponds directly with memory means block 34 of block diagram 30 ; conversion means circuit 56 which corresponds directly with conversion means block 36 of block diagram 30 ; amplification means circuit 58 which corresponds directly with amplification means block 38 of block diagram 30 ; and reset means circuit 62 which corresponds directly with reset means block 42 of block diagram. Of course both electronic circuit 50 and block diagram 30 control stepper motor 24 which is shown only in block diagram 30 .
Description/Function of Stepper Motor Control System
Referring now to FIGS. 3 and 4, there will be described the description/function of the individual blocks of block diagram 30 and their directly corresponding individual circuits of electronic circuit 50 .
Counter Means: The counter means 32 counts the number of half steps taken by the motor 24 , and sends this count to the Memory Means 34 . The counter advances 400 steps during 1 revolution, and then is reset by the Reset Means 42 .
Memory Means: The memory means 34 contains 400 numbers, each number representing the velocity of the motor 24 at each of the 400 steps. The specification of which of the 400 numbers to access is provided by the counter means 32 and the number is output to the conversion means 36 .
Conversion Means: The conversion means 36 takes the number from the memory means 34 representing the motor velocity, and loads the number into an internal conversion means counter. The internal conversion means counter then counts down to zero at a constant rate. When the internal conversion means counter reaches zero, a pulse is output to the Counter Means 32 to advance the counter means 32 by 1, and to the Amplifier Means 38 to advance the stepper motor 24 by half a step. Note that larger numbers provided to the Conversion Means 36 represent slower velocities, since the time required to count to zero is longer.
Amplifier Means: The pulse from the Conversion Means 36 causes the amplifier means 38 to advance the stepper motor 24 by half a step. Reset Means: Once per revolution, an optical sensor 30 which may be mounted on the stepper motor 24 sends a signal to the Counter Means 32 when flag 31 passes there through (FIGS. 2 and 2A) that resets the count. If the stepper motor 24 has missed a step during the prior revolution, the counter means will be resynchronized with the actual position of the stepper motor at this point.
Referring now to FIG. 5 there is shown a graph 70 of the non-sinusoidal angular velocity output of the rotary positive displacement pump 22 driven by a stepper motor 24 , constructed according to the teachings of the invention. Steps 0 - 99 are the second half of the upstroke, steps 100 - 199 are the first half of the downstroke, steps 200 - 299 are the second half of the downstroke, and steps 300 - 399 are the first half of the upstroke. To maintain a constant upstroke velocity between steps 0 - 99 , the motor's rotational velocity must become very large as it approaches the end of the upstroke. This requires a very large acceleration. The torque required to achieve this acceleration must be compared to the torque available from the motor. At some point near the end of the upstroke, the acceleration will be limited by the torque available from the motor. With moderately sized stepper motors, this limitation occurs at around step 95 . So between steps 0 - 95 , a constant flow profile is maintained, and between steps 96 - 100 , the flow profile is torque limited.
The downstroke time, from steps 100 - 299 , must be minimized. Therefore, to accomplish this, acceleration is maximized between steps 100 - 199 , and deceleration is maximized between steps 200 - 299 . The maximum available motor torque is determined at each step, and then the maximum acceleration or deceleration is determined. With a moderately sized stepper motor, the downstroke requires a period of about 58 milliseconds.
Lastly, to maintain a constant upstroke velocity between steps 300 - 399 , the motor must be rapidly decelerated as it enters the beginning of the upstroke to maintain a constant upstroke velocity. Again, the torque required to achieve this deceleration must be compared to the torque available from the motor. The deceleration is torque limited between steps 300 - 305 , and a constant flow profile is maintained between steps 306 - 399 . The process is then repeated starting with step 0 .
The speed of the individual steps as shown on graph 5 in half steps per second will be calculated by means of a stepper pump profile calculation.
Stepper Pump Profile Calculation
Calculate 2nd half upstroke (400 steps/revolution, so 100 steps for second half upstroke)
For i=0 to 99 do
Steps/sec=A/sin(B*i) [where A and B are constants representative of and derived from the stroke volume of the pump 72 (FIG. 2) and desired flow rate to the load 82 (FIG. 7 ), respectively]
Calculate torque required for next step acceleration
Compare to torque available from motor at this speed
Limit acceleration if necessary
Convert steps/sec to counter counts
Write counter counts to profile file and store in Memory Means 34
Calculate 1st half downstroke
For i=100 to 199 do
Calculate maximum torque available from motor at steps/sec
Subtract torque required to overcome friction to determine torque available for acceleration
Calculate maximum increase in steps/sec using torque available for acceleration
Calculate new steps/sec
Convert steps/sec to counter counts
Write counter counts to profile file and store in Memory Means 34
Calculate 2nd half downstroke
For i=200 to 299 do
Steps/sec[i]=steps/sec[400−i] for mirror image of 1st half downstroke
Write counter counts to profile file and store in Memory Means 34
Calculate 1st half upstroke
For i=300 to 399 do
Steps/sec[i]=Steps/sec[400−i] for mirror image of 2nd half upstroke
Write counter counts to profile file and store in Memory means 34 .
When the pump has been driven by the motor at the motor velocity shown in FIG. 5, the flow rate verses time of the graph shown in FIG. 6 is the resulting output. Please note the flat, constant step function portions 80 that represent the upstroke portion of the motor/pump rotation and the interruptions 82 to this constant step function 80 that represent the downstroke portions of the motor/pump rotation. The teachings of the invention endeavor to minimize these interruptions 82 , with the ideal condition of eliminating these downstroke interruptions altogether. This is accomplished according to the teachings of the invention by the use of a filtering means.
Referring now to FIG. 7, there is shown a schematic drawing of the output filter apparatus 100 that is placed in series with the output flow of the rotary positive displacement pump of the invention to minimize the flow interruption when the motor is turning the pump in the downstroke portion of the cycle.
Pump 72 's output is fed through two elastic members 74 , 78 respectively, and a resistive member 76 , which together with load 82 , comprise filter apparatus 100 . Elastic members 74 , 78 may be for instance, 0.132 diameter Silastic tubing and resistive member 76 may be for instance, a 0.007 inch orifice. 80 represents the output flow after passing through the elastic and resistive members, 82 represents the load and 84 is atmosphere.
FIG. 6 shows the output of pump 72 without the benefit of Filter apparatus 100 and FIG. 8 shown the output of pump 72 with filter apparatus 100 . It is evident that the flow 80 is nearly constant (to approximately 0.2% of the flow rate's original amplitude).
In conclusion, what has been disclosed is means and methods for changing the analog motion of an electric motor to a digital representation both in the profile and in the actual performance, i.e., the positioning, of the electric motor by means of the motor control system of the invention coupled with a standard stepper motor that is available in the art. The flow profile shown in FIG. 6 has a constant flow during the upstroke, but no flow during the downstroke. Although the downstroke time is only {fraction (1/30)} of the upstroke time in this embodiment of the invention, this interruption of flow is not desirable in flow applications, for which the invention was developed. In order to suppress this interruption of the flow rate, compliant tubing and a resistive orifice can be added to the output of the pump. FIG. 7 illustrates the filter configuration used to suppress the interruptions of flow shown in FIG. 6 . This filter consist of two compliant lengths of tubing separated by a resistive orifice. In this particular embodiment of the invention, the flow rate decreases by only 0.2% during the downstroke, or conversely, the flow remains at 99.8% of its desires output during the downstroke, i.e. approximating the ideal conditions of eliminating the downstrokes altogether.
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The present invention is a means and method for providing constant output flow from a fluid pump. The invention does this by controlling the radial speed of the pump motor during discreet segments of the motor's 360° angular/radial path through a revolution of the pump. The electric pump motor is controlled throughout the 360° radial path by employing a control means for controlling the speed of actuation of the radial steps of a stepper motor throughout the 360° path of rotation of the stepper motor. Control means for controlling the speed of the discreet steps of the stepper motor comprises at least a memory means, a counting means and an amplification means.
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The present invention is directed to a novel sliding door assembly, and particularly to a sliding door assembly useful with elevators.
BACKGROUND
Various assemblies for providing (vertical) support while permitting (lateral) movement of doors are known in the art. Such assemblies have been utilized for elevator cab and hoistway door panels, doors on railway freight cars, as well as other types of slidable doors. The present invention is useful in many types of slidable doors, but will be described herein with reference to elevator doors for which it is particularly useful
Conventional sliding door assemblies typically comprise a door track, a door hanger, a hanger sheave and an upthrust roller. The door hanger is a support which is typically fastened to the upper portion of a door panel, and which supports and allows the sliding movement, e.g. horizontally, of the door panel. The hanger sheave typically comprises a wheel or roller that is connected to a door panel by the door hanger. The door track is a rail which accepts the rolling assembly of door hanger and allows the horizontal sliding movement required to open and close the doors. An upthrust roller is a roller bearing installed onto an eccentric shaft and mounted on the door hanger for limiting the (vertical) motion of a (horizontally) sliding door panel to keep the panel from lifting off the door track.
One such type of conventional elevator door assembly known in the art is shown in FIG. 1 wherein an elevator cab or hoistway door panel 10 (hereinafter the door panel) is slidably supported on door track 50 via door hanger 20. A hanger sheave (roller) assembly 30 is rotatably mounted on door hanger 20. Hanger sheave assembly 30 is designed to receive projecting portions 51 of door track 50. Though not shown in FIG. 1, door track 50 is securely mounted such that it can support door panel 10. To prevent the hanger sheave assembly 30 from jumping off door track 50 when the elevator door 10 is jolted by mechanical means or by people moving equipment onto or out of the elevator, the conventional design incorporated an upthrust roller 40 mounted on door hanger 20. The upthrust roller 40 is conventionally placed slightly below and in close proximity to, for example, 0.020-0.030 inches, door track 50. Thus, in normal operation, hanger sheave assembly 30 rolls along door track 50 and projections 51 and upthrust roller 40 only contacts projections 51 if the elevator door 10 is jolted. Upthrust roller 40 is conventionally eccentrically mounted on door hanger 20 via adjustable mount 45 in a manner which permits the adjustment of the gap between upthrust roller 40 and door track 50.
The traditional assembly containing a track, hanger, hanger sheave and upthrust roller has provided fairly good service through the years. However, one inherent problem still exists. This problem is caused by the wearing of the hanger sheave 31 and its effect upon the critical relationship between the upthrust roller 40 and track 50. For example, as the hanger sheave 31 wears, a gradual but substantial clearance will develop between the underside of the door track 50 and the upthrust roller 40. If a periodic re-adjustment is not performed to the upthrust roller 40, the hanger sheave assembly 30 may easily jump off of the track 50. This often occurs when the door panels 10 are struck by mechanical means or by person moving equipment on or out of the elevators.
Another disadvantage of the conventional design shown in FIG. 1 is that since hanger sheaves are typically formed of synthetic materials such as nylon or another plastic material which may readily melt in the event of a fire, the door panel 10 could easily become stuck thereby trapping the occupants in the elevator.
Another known design for a door hanger is shown in U.S. Pat. No. 807,141, to J.J. Tatum, patented Dec. 12, 1905. That design incorporates two rollers, C C, which are positioned about a rail 1. That patent does not disclose the desirability of adjusting the bottom roller and lacks the advantages of the present invention described below.
Another known assembly is disclosed in U.S. Pat. No. 1,024,502, to P.M. Elliott, patented Apr. 30, 1912, which discloses a door mechanism for a railway freight car and antifriction roller F which rests upon the upper face of a track flange b 2 and a small roller F' positioned below the track flange.
Another sliding door assembly is shown in Patentschrift, No. 964,030, dated May 16, 1957. From the figures of this Patentschrift, it is apparent that this design utilizes rollers within a rail but does not disclose the use of upthrust rollers. With reference to FIG. 4, it will be appreciated that the two rollers 123 and 223 each support different elements 113 and 213, respectively.
Still another known arrangement is disclosed in U.S. Pat. 4,120,072, to M. Hormann, patented Oct. 17, 1978, for a COMBINED SUPPORTING ROLLER-FRICTION DRIVE ARRANGEMENT FOR OVERHEAD SINGLE-PANEL DOORS. This design is somewhat similar to that described above with reference to prior art FIG. 1 wherein a roller 6 rides on a running track 8, however in this design, counterpressure rollers 12 contact the underside 13 of running track 8. Counterpressure rollers 12 are provided with an adjusting means 16 permitting the adjustment of the counterpressure rollers 12 in the direction toward the running track 8. In accordance with this design, at least one of the counterpressure rollers 12 is always in contact with the bottom side 13 of the running track 8. (see column 3, lines 49-55)
It will be appreciated that the known sliding door assemblies which utilize an upthrust roller in close proximity to the track require continual maintenance to ensure that the gap between the upthrust roller and door track does not become so great that the hanger sheave can be jolted off the track. The other designs which place the track assembly in continuous contact with an upthrust roller result in the wearing down of not only the hanger sheave but also the upthrust roller and, if the upthrust roller is formed of a metal such as steel, may cause an irritating noise during use.
SUMMARY
The present invention overcomes the disadvantages of the previously known assemblies with a sliding door assembly comprising a door hanger, a hanger sheave assembly, an upthrust roller and a track, wherein the hanger sheave assembly and the upthrust roller are rotatably mounted on the door hanger. In accordance with the present invention the track provides a first rolling surface for the hanger sheave and a second rolling surface for the upthrust roller. The track also preferably captures the upthrust roller thereby preventing the assembly from leaving the track.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view of a conventional sliding door assembly of the prior art.
FIG. 2 is a cross-sectional view of the sliding door assembly of the present invention.
DETAILED DESCRIPTION
The present invention comprises a novel track and sliding door assembly which is useful for suspending and guiding sliding doors such as the sliding door panels of an elevator cab or hoistway doors.
With reference to FIG. 2, the present invention comprises sliding door assembly 100 comprising a track 150, a door hanger 120 supporting a moveable door panel 101. A hanger sheave assembly 130 is rotatably mounted on door hanger 120. The hanger sheave assembly 130 comprises a bearing 131, a sheave 132 and may also advantageously comprise an insert 133. The sheave assembly 130 is rotatably mounted on hanger 120 with axle 135. In operation, the sheave assembly 130 slidably supports the hanger 120 and thereby the door panel 101 on track 150. It will be appreciated by those skilled in the art that the insert 133 may be advantageously formed of a non-metallic material, such as rubber or polyurethane in order to reduce the amount of noise created when the sheave 132 rolls along track 150.
The present invention also comprises an upthrust roller 140 which is also rotatably mounted on hanger 120, via upthrust roller shaft 145.
Track 150 is securely mounted in a manner in which it can provide support to hanger 120 and door panel 101, for example, via a bolt 160 which secures track 150 to, for example, a header 170. Track 150 is configured and mounted such that it provides an exterior, upper rolling surface 151 upon which sheave assembly 130 rolls during normal operation, and also comprises interior, upthrust rolling surfaces 152A and 152B upon which upthrust roller 140 can roll and be supported when captured in track 150. Track 150 also preferably comprises outer lips 155 and 156 which "capture" upthrust roller 140 and thereby prevent the hanger 120 and attached door panel 101 from becoming dislodged from track 150.
By the term "capture" it is meant that the track 150 surrounds enough of the upthrust roller 140 to prevent the upthrust roller from exiting the interior portion of track 150. With reference to FIG. 2, it will be appreciated that lips 155 and 156 sufficiently enclose the upthrust roller 140 to prevent the lateral exiting of the upthrust roller 140 from the interior portion of the track 150.
In accordance with the present invention, when the sliding door assembly 100 is in normal operation, sheave assembly 130 provides rolling support for hanger 120 and door panel 101, and rolls along the exterior, upper surface 151 of track 150. As the sheave assembly insert 133 wears, the hanger 120 will move downwardly relative to track 150 also causing the lowering of upthrust roller 140 within track 150. This downward relative movement is stopped when roller 140 contacts interior, lower rolling surface 152(A) of track 150.
While the upthrust roller 140 may be formed of any suitable load bearing material, it is preferable that the upthrust roller be made of steel. Thus, in the unfortunate event of a fire, the insert 133, which as stated above can be formed of a synthetic material such as nylon or another plastic, may melt and therefore no longer support hanger 120. In such circumstances, the sliding door assembly 100 of the present invention continues to provide rolling support for door panel 101 via upthrust roller 140 and interior, lower rolling surface 152(A) of track 150. In this case, the upthrust roller 140 formed of suitable metal e.g. steel, will still allow the free movement of the door panel 101, albeit noisy. As stated above, upthrust roller 140 also contacts interior roller surface 152 under less traumatic circumstances as when the sheave simply wears down. Under these circumstances, the noisy operation of the sliding door panel 101 provides an indication to maintenance personnel that the sheave should be replaced.
Thus it will be appreciated that the novel track design of the present invention provides at least two major advantages with respect to conventional tracks previously employed in sliding door assemblies. First, by the preferred "capturing" of the upthrust roller, the sheave assembly 130 and hanger 120 are prevented from being knocked off the track 150. Secondly, if the insert material 133 which serves somewhat as a tire on the hanger sheave 132 becomes completely worn away, the interior, lower roller surface 152 of the track supports the upthrust roller 140 and thereby serves as a means by which the door panel 101 may continue to move along the track 150. This feature advantageously reduces the risk of passengers being trapped inside elevator cabs due to faulty or damaged sliding door assemblies.
The novel track configuration 150 illustrated in FIG. 2 provides the further advantage of being reversible. It will be appreciated by those skilled in the art, that track 150 can simply be rotated such that the bottom portion of the track 150 as shown in FIG. 2 becomes the top. It will also be appreciated that track 150 can serve both as a left hand track and a right hand track due to its symmetrical configuration as shown in FIG. 2. While such a reversible track configuration 150 as shown in FIG. 2 is preferred, this reversibility is not necessary for the practice of the present invention.
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A sliding door assembly comprising a door hanger, a hanger sheave, an upthrust roller and a track, wherein the hanger sheave assembly and the uptrust roller are rotatably mounted on the door hanger. The track provides a first rolling surface for the hanger sheave and a second rolling surface for the upthrust roller. The track also preferably captures the upthrust roller thereby preventing the assembly from leaving the track.
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FIELD OF INVENTION
This invention relates generally to turbochargers used with internal combustion engines, and more particularly to turbochargers with integral assisting electric motors, and to structures for, and methods of combining, the components of the assisting electric motor and the turbocharger.
BACKGROUND OF THE INVENTION
Turbochargers are well known and widely used with internal combustion engines. Generally, turbochargers supply more charge air for the combustion process than can otherwise be induced through natural aspiration. This increased air supply allows more fuel to be burned, thereby increasing power and torque obtainable from an engine having a given displacement. Additional benefits include the possibility of using lower displacement, lighter engines with corresponding lower total vehicle weight to reduce fuel consumption, and use of available production engines to achieve improved performance characteristics. Some turbocharger applications include the incorporation of an intercooler for removing heat (both an ambient heat component and heat generated during charge air compression) from the charge air before it enters the engine, thereby providing an even more dense air charge to be delivered to the engine cylinders. Intercooled turbocharging applied to diesel engines has been known, in some applications, to double the power output of a given engine displacement, in comparison with naturally aspirated diesel engines of the same engine displacement.
Additional advantages of turbocharging include improvements in thernal efficiency through the use of some energy of the exhaust gas stream that would otherwise be lost to the environment, and the maintenance of sea level power ratings up to high altitudes.
At medium to high engine speeds, there is an abundance of energy in the engine exhaust gas stream and, over this operating speed range, the turbocharger is capable of supplying the engine cylinders with all the air needed for efficient combustion and maximum power and torque output for a given engine construction. In certain applications, however, an exhaust stream waste gate is needed to bleed off excess energy in the engine exhaust stream before it enters the turbocharger turbine to prevent the engine from being overcharged. Typically, the waste gate is set to open at a pressure, above which undesirable predetonation or an unacceptably high internal engine cylinder pressure may be generated.
At low engine speeds, such as idle speed, however, there is disproportionately less energy in the exhaust stream as may be found at higher engine speeds, and this energy deficiency prevents the turbocharger from providing a significant level of boost in the engine intake air system. As a result, when the throttle is opened for the purpose of accelerating the engine from low speeds, such as idle speed, there is a significant time lag, i.e., turbo lag, and corresponding performance delay, before the exhaust gas energy level rises sufficiently to accelerate the turbocharger rotor and provide the compression of intake air needed for improved engine performance. The performance effect of this turbo lag may be more pronounced in smaller output engines which have a relatively small amount of power and torque available before the turbocharger comes up to speed and provides the desired compression.
Various efforts have been made to address the problem of turbo lag, including a reduction in the inertia of the turbocharger rotor. In spite of evolutionary design changes for minimizing the inertia of the turbocharger rotor, however, the turbo lag period is still present to a significant degree, especially in turbochargers for use with highly rated engines intended for powering a variety of on-highway and off-highway equipment.
Furthermore, to reduce exhaust smoke and emissions during acceleration periods when an optimal fuel burn is more difficult to achieve and maintain as compared with steady-speed operation, commercial engines employ devices in the fuel system to limit the fuel delivered to the engine cylinders until a sufficiendy high boost level can be provided by the turbocharger. These devices reduce excessive smoking, but the limited fuel delivery rate causes a sluggishness in the response of the engine to speed and load changes.
The turbo lag period can be mitigated and, in many instances, virtually eliminated by using an external power source to assist the turbocharger in responding to engine speed and load increases. One such method is to use an external electric power supply, such as the electrical energy stored in batteries, to power an electric motor that has been integrated into the mechanical design of a turbocharger. By providing the motor components within the turbocharger housing, the turbocharger bearings can also serve as motor bearings.
Providing motor components within a turbocharger assembly presents, however, a number of problems. Such motor components include permanent magnets to provide an electric motor rotor and wire windings to provide an electric motor stator, and the permanent magnets and stator windings must be in sufficient proximity to permit a relatively efficient conversion of electric energy applied to the stator windings into rotational energy imparted to the turbocharger rotor by the permanent magnets. The attachment of permanent magnets to the shaft exposes the permanent magnets to heat which is conducted down the shaft from the exhaust gas turbine wheel, and the exposure of the permanent magnets to such heat and their resulting temperatures may deleteriously affect the permeability and magnet field strength of the rotor magnets and result in insufficient and ineffective operation of the electric motor. In addition, the permanent magnets are exposed, in their rotation, to significant centrifugal forces since the turbocharger shaft can rotate at speeds up to 100,000 rpm and higher. The addition of stator windings within a turbocharger assembly also presents problems because the high temperatures that are reached in the turbocharger assembly can adversely affect the electrical insulation of the stator windings leading to possible failure.
A turbocharger assembly, including an integral assisting motor is disclosed in our prior U.S. patent application Ser. No. 08/680,671, filed Jul. 16, 1996, and U.S. Ser. No. 08/731,142, filed Oct. 15, 1996, which have addressed these problems and others.
Other patents disclosing turbocharger-electrical machine combinations include U.S. Pat. Nos. 5,406,797; 5,038,566; 4,958,708, 4,958,497; 4,901,530; 4,894,991; 4,882,905; 4,878,317, and 4,850,193.
BRIEF STATEMENT OF THE INVENTION
The invention provides a new integral turbocharger-electric motor assembly in which the elements of an operating electric motor and turbocharger can be easily assembled into a relatively compact and reliable operating unit. Such a turbocharger-motor assembly includes a central portion between the turbocharger turbine and compressor including a housing carrying, in a cooled supporting portion, a stator winding for the electric motor and providing bearing support adjacent its ends for the turbocharger shaft. To act as the electric motor rotor, the turbocharger shaft carries a magnet assembly in its central portion between the shaft bearings, in such proximity to the stator windings to provide electromagnetic coupling for the effective conversion of electric energy applied to the stator winding into rotational force applied by the magnet assembly to the turbocharger shaft. In preferred such assemblies, the turbocharger housing includes a conduit for coolant for the stator windings.
In the invention, the magnet assembly includes a plurality of permanent magnets located around a central core and secured against centrifugal force by a non-magnetic outer sleeve. Preferably, such magnet assemblies are formed as a unit that can be assembled onto the turbocharger shaft by retaining an annular arrangement of motor magnets in an assembly between central and outer sleeves. In a preferred embodiment of the invention, the magnets can be secured around the central sleeve and within the retaining sleeve by a high-temperature structural adhesive, and the retaining sleeve can include inwardly projecting portions at its ends for an engagement with the ends of the magnets. Such a magnet assembly can be removably mounted on the turbocharger shaft between the turbocharger bearings and clamped in place by the axial force exerted on its ends by shaft sleeves when a rotor lock nut is tightened. The central core of the magnet assembly may be formed with a plurality of planar magnet-locating surfaces and ends, having a reduced surface area to reduce heat transfer to the magnets. In preferred magnet assemblies the inside surface of the central sleeve may be relieved in its central portion to reduce the area of contact with the turbocharger shaft, and reduce the heat flow from the shaft into the magnet assembly. In addition, in the turbocharger-electric motor assembly, or in the magnet assembly itself, insulating material may be placed between the central sleeve of the magnet assembly and the turbocharger shaft to limit heat transfer into the magnet assembly.
Further features and advantages of the invention will be apparent from the drawings and more detailed description that follows.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view, taken at a vertical plane through its central axis, of one turbocharger-electric motor assembly of the invention, including a magnet assembly removably mounted between clamping sleeves on a turbocharger shaft, a plurality of motor stator windings positioned in the central housing, and a surrounding cooling conduit;
FIGS. 2-5 illustrate magnetic assemblies of the invention;
FIG. 2, for example, is an end view of the magnet assembly, taken at a plane along line 2--2 of FIG. 1, showing a central sleeve surrounded by a plurality of magnets encompassed by an outer retaining sleeve;
FIG. 3 is a cross-sectional view of the magnet assembly of FIG. 2 taken at a plane through its central axis;
FIG. 4 is a cross-sectional view of another magnet assembly of the invention taken at a plane through its central axis, illustrating relief of the inner surface of the magnet assembly for reduced contact with the turbocharger shaft; and
FIG. 5 is a cross-sectional view through a magnet assembly and a central portion of a turbocharger shaft taken at a plane through their central axes, illustrating a thermal insulative element between the turbocharger shaft and the magnet assembly;
FIG. 6 is a cross-sectional view of another embodiment of a magnet assembly of the invention taken at a plane through its central axis; and
FIG. 7 is a cross-sectional view of still another embodiment of a magnet assembly of the invention in place on a turbocharger shaft, taken at a plane through their central axes.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, and particularly to FIG. 1, a turbocharger 10 combines the elements of an electric machine and a turbocharger in accordance with this invention. The turbocharger assembly 10 comprises an exhaust gas turbine 11 at one end, a charge air compressor 12 at the other end, and an assisting electric motor 13 in a central housing 14 of the turbocharger 10. The central housing 14 supports, through bearings at its turbine end and compressor end, a multi-vaned turbine wheel 15, a compressor wheel 16 having a plurality of vanes 17, and an interconnecting rotatable shaft 18. The turbine 11 includes a turbine housing 20 which forms an exhaust gas inlet scroll 21 that is connected to receive exhaust gas from an internal combustion engine (not shown). Internal combustion engines frequently have exhaust manifolds divided into two sections, each section receiving exhaust gas from a separate set of cylinders (not shown). The exhaust gas is directed from the inlet scroll 21 to drive the turbine wheel 15 and shaft 18 in rotation. After passing through the turbine wheel 15, the exhaust stream flows out of the turbocharger through an exhaust vent 22.
Rotation of the shaft 18 rotates the compressor wheel 16 at the opposite end of the interconnecting shaft 18, and air is drawn in through an air intake opening 23 formed in a compressor casing 24 after passing through an appropriate air filter (not shown) to remove contaminants. The compressor casing 24 includes a scroll 25 for directing the compressed combustion air to an engine air intake manifold (not shown).
In the invention, the elements of electric motor 13 are incorporated in the central portion of the turbocharger assembly 10. The elements of the assisting electric motor comprise a stator 30, including a plurality of pole-forming laminations of magnetic material and wire windings for the poles so formed, that is carried by housing 14, and a rotor including a plurality of magnets in a magnet assembly 32 that is carried by and attached to the rotatable shaft 18. In the assembly the rotor magnets of the magnet assembly 32 are carried in electromagnetic proximity to the poles formed by the lamination and windings of the stator 30 so that a rotating magnetic field formed by the application of electrical energy to the stator windings can effectively coupled with the magnetic field of the rotor magnets and drive the rotatable shaft 18 in rotation. In the preferred assembly of FIG. 1, the housing 14 provides cooled support for the stator windings. For example, as shown in FIG. 1, the housing 14 is formed with a coolant conduit 29 in such proximity to the housing surfaces in contact with the stator 30 that circulation of a coolant, such as engine coolant, can maintain the temperature of the stator windings below a temperature that may be damaging to their electrical insulation. The invention provides an easily assembled and reliably operable motor-assisted turbocharger. As set forth below, the rotor 31 of the electric motor can comprise a unitary magnet assembly 32 carrying the plurality of rotor magnets in a spaced arrangement about the rotatable shaft 18 of the turbocharger for effective interaction with the stator 30 when energized. The unitary magnet assembly 32 may be slipped onto the rotatable shaft 18 and fixed to the shaft to transfer rotational force from the magnet assembly 32 to the shaft 18 and assist in the rotation of compressor wheel 16 by the turbine wheel 15.
For example, the rotating elements of turbocharger assembly 10 can be attached together as a rotating unit by a lock nut 26 that compresses the rotating elements against a shoulder 18a formed on the rotating shaft 18. As illustrated by FIG. 1, mounted on the shaft 18 in succession are compressor wheel 17, sleeve 40, thrust collar 41, bearing sleeve 42, magnet assembly 32, seal sleeve 43, with sleeve seal 43 bearing against a shoulder 18a on shaft 18. The lock nut 26 exerts an axial force on all these members to maintain them as a rotating unitary assembly. The magnet assembly 32 is thus clamped tightly on shaft 18 between the bearing sleeve 42 and the seal sleeve 43 and can apply rotational forces to the shaft 18.
The stator windings 30 of the motor can be mounted in the turbocharger central housing 14 and secured by a set screw (not shown). Winding wires 27 can exit the housing 14 through passageway 28 for connection to an appropriate electronic control and power supply. As shown in FIG. 1, the coolant conduit 29 surrounds stator windings 30 and is separated from the stator 30 by a relatively thin housing wall, which can transfer heat from the stator windings 30 to a coolant in conduit 25. Cooling conduit 29 has inlet and outlet connections (not shown) to receive a cooling fluid from the internal combustion engine cooling system.
Thus, when the stator 30 is energized, rotational forces are applied to the shaft 18 on which the compressor wheel 17 is mounted and augment the torque being applied to the shaft 18 by the exhaust gas turbine 11, thereby causing the assembly to rotate faster than if it were not equipped with the assisting motor 13. The faster rotation of the shaft 18 when the assisting motor 13 is energized drives the compressor wheel 17 to supply the engine with a greater flow of charge air at higher pressure, thereby improving engine performance while reducing the amount of smoke and pollutants emitted during acceleration of the engine.
The components of the turbocharger not discussed in detail are well known in the art, such as shaft bearings and oil seal elements necessary for reliably supporting the rotating assembly and for containment of the lubricating oil that is conventionally supplied from the engine's pressurized oil system to lubricate and cool the bearings.
FIG. 2 is a cross-sectional view of the magnet assembly 32 of FIG. 1, taken at a plane corresponding to line 2--2 of FIG. 1, and FIG. 3 is a cross-sectional view of the magnet assembly 32 taken at a plane corresponding to line 3--3 of FIG. 2. As shown in FIGS. 2 and 3, magnet assembly 32 includes a sleeve-like inner core 33 of a magnetic material, such as carbon steel, on which a plurality of permanent motor magnets 34 are placed. As shown by FIG. 2, the inner core 33 is formed with a plurality of planar magnet-locating surfaces 33a for spacing the magnets 34 about the turbocharger shaft for interaction with the poles formed by the stator 30. As also shown in FIGS. 2 and 3, the inner core 33 has ends 33b with reduced surface areas (e.g., minimal thicknesses) to reduce the heat transfer to the magnets 34 from the adjacent turbocharger parts. The magnets 34 are encompassed and retained by an outer, non-magnetic sleeve 35 designed with sufficient strength to hold the magnets 34 in place at the maximum rotational speed of the turbocharger. The inner core 33, magnets 34 and outer sleeve 35 comprise a unitary magnetic assembly 32 which serves as the electric motor rotor in the turbocharger assembly 10. In preferred embodiments, the components of the magnet assembly can also be secured together as a unit by an appropriate high temperature structural adhesive.
FIG. 4 is a cross section of another magnet assembly 36, in which the inner core 37 has been formed with a inner surface portion 37a having an increased diameter so that it is removed from contact with the shaft 18, and radialy-inwardly extending portions 37b bracketing the inner surface portion 37a for supporting the core 37 on the shaft 18. The resulting reduced contact area between the inner core 37 and shaft 18 reduces the heat transfer from the turbocharger shaft 18 to the permanent magnets 34.
FIG. 5 is a cross-sectional view of the magnet assembly 32 of FIGS. 2 and 3 assembled onto the shaft 18 with thermal insulating numeral between the inner core 33 and the turbocharger shaft 18 to reduce heat transfer from the turbocharger shaft 18 to the permanent magnets 34. As shown in FIG. 5 the thermal insulating material may be conveniently in the form of a thermally insulative sleeve 38 between the inner core 33 and shaft 18.
FIGS. 6 and 7 illustrate further embodiments of a magnet assembly of the invention. In the embodiments of FIGS. 6 and 7, the sleeve-like inner core can be in all respects identical to the sleeve-like inner core shown in FIGS. 2-4, forming a plurality of planar magnet locating surfaces 33a for spacing magnets 34 about the turbocharger shaft. In the magnet assembly of FIG. 6 the outer non-magnetic metallic sleeve 39 has its ends 39a and 39b rolled inwardly over the ends of the permanent magnets 34 as shown in the FIG. 6 cross-section. In the embodiment of FIG. 7, the outer non-magnetic metallic sleeve 40 comprises two sections 41 and 42 which are preferably identical. Each of the sections 41 and 42 is formed with an inwardly extending annular flange 41a, 42a, providing a cup-like form. In the embodiment of FIG. 7 each of the sections 41 and 42 may be slid over the magnets 34 until their inwardly extending annular flanges 41a and 42a engage the ends of the magnets 34. In the embodiment of FIG. 7 the two cup-like sleeve sections 41 and 42 may be secured in place by suitable adhesive or by shrink fit onto the magnets 34. In the embodiments of FIGS. 6 and 7, the outer sleeves 39 and 40 help prevent axially displacements of the magnets 34 of the magnet assembly.
While preferred embodiments of the invention have been illustrated and described, the invention can be incorporated in other embodiments and should be limited only by the scope of the following claims and the prior art.
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An integral turbocharger-electric motor assembly permits the elements of an operating electric motor and turbocharger to be easily assembled into a relatively compact and reliable operating unit. To act as an electric motor rotor, the turbocharger shaft carries a magnet assembly in its central portion between the shaft bearings, in such proximity to the stator windings to provide electromagnetic coupling for the effective conversion of electric energy applied to the stator winding into rotational force applied by the magnet assembly to the turbocharger shaft. The magnet assembly includes a plurality of permanent magnets located around a central core and secured against centrifugal force on a non-magnetic outer sleeve. Such magnet assemblies are preferably formed as a unit that can be assembled onto the turbocharger shaft by retaining an annular arrangement of motor magnets in an assembly between central and outer sleeves.
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RELATED APPLICATIONS
This application is a continuation-in-part application of U.S. patent applications Ser. Nos. 08/231,614 filed on Apr. 22, 1994, pending, and 08/237,732 filed on May 4, 1994 now U.S. Pat. No. 5,527,441.
FIELD OF THE INVENTION
This invention relates to the welding of piping and other residual stress-sensitive components. In particular, the invention relates to the welding of piping and other components used in nuclear reactors, which components are susceptible to stress corrosion cracking in the heat affected zones adjacent to a weldment.
BACKGROUND OF THE INVENTION
A nuclear reactor comprises a core of fissionable fuel which generates heat during fission. The heat is removed from the fuel core by the reactor coolant, i.e. water, which is contained in a reactor pressure vessel. Respective piping circuits carry the heated water or steam to the steam generators or turbines and carry circulated water or feedwater back to the vessel. Operating pressures and temperatures for the reactor pressure vessel are about 7 MPa and 288° C. for a boiling water reactor (BWR), and about 15 MPa and 320° C. for a pressurized water reactor (PWR). The materials used in both BWRs and PWRs must withstand various loading, environmental and radiation conditions. As used herein, the term "high-temperature water" means water having a temperature of about 150° C. or greater, steam, or the condensate thereof.
Some of the materials exposed to high-temperature water include carbon steel, alloy steel, stainless steel, and nickel-based, cobalt-based and zirconium-based alloys. Despite careful selection and treatment of these materials for use in water reactors, corrosion occurs on the materials exposed to the high-temperature water. Such corrosion contributes to a variety of problems, e.g., stress corrosion cracking, crevice corrosion, erosion corrosion, sticking of pressure relief valves and buildup of the gamma radiation-emitting Co-60 isotope.
Stress corrosion cracking (SCC) is a known phenomenon occurring in reactor components, such as structural members, piping, fasteners, and welds, exposed to high-temperature water. As used herein, SCC refers to cracking propagated by static or dynamic tensile stressing in combination with corrosion at the crack tip. The reactor components are subject to a variety of stresses associated with, e.g., differences in thermal expansion, the operating pressure needed for the containment of the reactor cooling water, and other sources such as residual stress from welding, cold working and other asymmetric metal treatments. In addition, water chemistry, welding, heat treatment, and radiation can increase the susceptibility of metal in a component to SCC. The present invention is concerned with mitigating welding-induced residual stresses and thermal sensitization, which can lead to SCC in susceptible metals.
A conventional V-groove weld 6 for joining two pipes 2 and 4 is illustrated in FIG. 1A. The weld 6 is formed by filling the V-groove with beads of fused material from a filler wire placed at the tip of a circular cylindrical welding electrode (not shown). This welding process produces a very wide heat affected zone (HAZ) in the vicinity of the welded joint. The occurrence of SCC in the vicinity of such welded joints has led to the need for repair or replacement of much of the piping in light water reactor power plants throughout the world. Numerous methods have been utilized for over a decade to improve the tensile residual stress state in the vicinity of welded joints, including magnetic induction, electrical resistance and electric arc heating methods. All of these methods are based on generating a substantial temperature difference through the welded material thickness by applying the heat source on one side of the material and maintaining water cooling on the other side of the material. This temperature difference produces thermal strains and subsequent material plasticity, and a corresponding stress reversal across the thickness of the material. The net result makes the residual stress on the side of the joint exposed to the potentially aggressive reactor water environment significantly less tensile or, more preferably, compressive. These previous methods, including "heat sink welding" and "last pass heat sink welding", have all relied on continuous water convective cooling of the environmentally exposed side of the weld joint in order to effect the required temperature difference and stress reversal. This water cooling requirement is a severe penalty to the fabricator whether the piping is being newly installed or replaced, since the complete piping system must be intact in order to contain the water. The typically used arc welding process which requires water cooling to effect the temperature gradient through the material thickness and a corresponding residual stress reversal has relatively low thermal and time efficiencies and utilizes a wide weld joint design with a low aspect ratio of joint depth to thickness. The reduction of tensile forces residing in the metal lattice structure by internal water cooling during welding serves to mitigate the occurrence of irradiation-assisted SCC, wherein impurities in the stainless steel alloy diffuse to the grain boundaries in response to the impingement of neutrons.
A second major contributor to SCC in stainless steels alloyed with chromium for corrosion resistance is the size and degree of thermal sensitization of the heat affected zone adjacent to the weld. Thermal sensitization refers to the process whereby chromium carbides precipitate in the grain boundaries of the material. The precipitation of chromium carbides ties up the chromium which would otherwise be in solution. Thus, a thin layer along the grain boundary is denuded of chromium, creating a zone which is no longer corrosion resistant and therefore is susceptible to SCC. Such stainless steels corrode at the grain boundaries preferentially.
One consideration in the design of welds for SCC resistance is the minimization of the heat input by the process to the component being joined. This heat input is typically maintained at a level sufficient to provide reliable fusion by the weld filler metal to the side walls of the joint, which have in other welding processes been separated by an amount necessary to move a circular cylindrical electrode in the joint.
Another contributor to SCC in corrosion stabilized austenitic stainless steels is the dissolution of stabilizing carbides near the fusion line of welds, which in turn can lead to grain growth and thermal sensitization when the welding heat input is excessively high. This particular variation of SCC is generally referred to as "knife line attack", as it often occurs in a localized region of the weld heat affected zone.
One type of reduced-groove-width welding process used commercially in power plant piping welds is so-called "narrow groove" welding, an illustration of which is given in FIG. 1B. This technique produces a weld 6' between pipes 2' and 4' which has a heat affected zone which is narrower than and a groove angle which is less than the HAZ and groove angle of the V-groove welding process. The "narrow groove" welding process uses a standard circular cylindrical electrode geometry. These standard electrodes come in various lengths and diameters, typically with a relatively pointed or conical end. However, in "narrow groove" welding, the reduction of the groove width has been limited by the minimum diameter of the electrode required to reliably carry the needed welding current. All previous welds, including "narrow groove" welds, have been made with the circular cylindrical electrode shape, which has become the industry standard. The minimum diameter of a circular cylindrical electrode is in turn limited by the electrical current-carrying and heat-dissipating capability of a given size. No provision has ever been made for the manufacture or installation of a noncylindrical electrode in either a V-groove or "narrow groove" weld application.
SUMMARY OF THE INVENTION
The present invention is a process for providing a significant improvement in the detrimental tensile residual stress condition on the root side of welds, especially on the inside wall of piping welds. The process uses a novel combination of welding parameters, in particular, extremely fast welding torch travel speed, especially on the last one or more passes, commonly referred to as the "cap" passes. In order to obtain the maximum stress improvement benefits, the process of the invention improves upon the low residual stress welding process disclosed in U.S. patent application Ser. No. 08/237,732, which welding technique employs a tungsten electrode blade having a non-circular cross section. That patent application discloses weld torch travel speeds in the range of 2 to 10 inches per minute. The process of the present invention can be performed employing the same flat electrode blade, but higher weld torch travel speeds, i.e., greater than 10 inches/min, particularly during the so-called "cap" passes.
The aforementioned low-residual-stress welding process has been shown to mitigate the normally high (approximately yield strength or greater) residual stress levels to a low value of tension substantially less than the yield strength or, preferably, to a state of compressive stress. This result has been achieved without the use of any supplementary cooling on either surface of the component being joined, as is sometimes utilized in water-cooled processes such as heat sink welding and last pass heat sink welding.
The process in accordance with the present invention is intended primarily for, but is not limited to, the welding or heat treatment of relatively thin materials (e.g., on the order of 3/8 inch thick). The process is considered to be welding if the underlying material of the weld joint is fused during the cap pass or passes. Alternatively, the process is considered to be a heat treatment if the underlying material of the weld joint is heated, but not fused during one or more passes of the welding electrode tip over the far surface (remote from the root) of the weld joint. The present invention encompasses both welding and heat treatment. The term "cap pass" as used herein includes the conventional cap pass or passes in a welding process as well as the heat treatment pass or passes.
The essence of the invention is, using a traveling welding torch, to input heat into the far surface (far from the weld root pass) at a rate such that the far surface is heated and the near surface is cooled (without utilizing external heat sinking, e.g., water cooling) to a degree such that reduced tensile stress or preferably compressive stress is produced in the near surface. Specifically, the process of the invention uses very high welding torch travel speeds during the cap passes, i.e., >10 inches/min, to obtain maximum stress mitigation benefits. This process, whether used as a welding process or as a heat treatment, is hereinafter referred to as "passive heat sink welding" to clearly distinguish it from the existing techniques which require fluid cooling (including gas cooling).
The process of the invention relies on the limited thermal heat sink capability of the pipe wall and nearly completed weld joint itself to generate a significant through-wall temperature gradient, and therefore a sufficient through-wall stress gradient during the welding. This stress gradient results in metal plasticity and permanent strains, and therefore a reduction in the magnitude of the final residual stress or, preferably as conditions allow, a reversal in the direction of the stresses from tensile to compressive. An adequate temperature gradient is achieved using the high torch travel speeds of the present invention, allowing the outer layer of the component wall to be sufficiently heated before excessive conduction through the wall to the inner layer can occur. This effect has been previously demonstrated in thicker wall (high heat sink) material at slower torch travel speed (i.e., 2-10 inches/min) in the low residual stress welding process. In accordance with the invention, this effect can also be obtained for thin wall material (low heat sink) at faster torch travel speeds (i.e., >10 inches/min).
A key difference between these two conditions is that for thin material, the stress reversal is achieved primarily incrementally during the cap pass or passes, whereas for the thick material the stress reversal is achieved progressively as the joint is completed. For welding without supplementary cooling on thin material, the heat input of the cap pass or passes can easily dominate the through-wall temperatures, whereas for thick materials, the heat input of the cap pass or passes has reduced effect on the through-wall temperature distribution. For welding with supplementary cooling, such as in the conventional heat sink welding and last pass heat sink welding processes, the heat of the last pass must be even higher to compensate for the effect of losses due to fluid cooling.
In accordance with a further aspect of the invention, the welding torch is oscillated laterally during the cap pass or passes. The purpose of lateral torch oscillation is to spread the heat on the far surface of the pipe in a manner that produces a reduced tensile stress substantially less than the yield strength or, preferably, a compressive stress over a wider axial length on the near surface, thereby reducing the concentration of bending moment applied across the weld root and mitigating fine circumferential cracking along the fusion line on either side of the weld.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a sectional view of a V-groove joint welded in accordance with a conventional welding technique.
FIG. 1B is a sectional view of a narrow-groove joint welded in accordance with another conventional welding technique.
FIG. 1C is a sectional view of a joint welded in accordance with the technique of the present invention.
FIGS. 2A-2C are front, side and bottom views respectively of a first electrode geometry which can be used to weld in accordance with the present invention.
FIGS. 3A and 3B are sectional views of alternative groove geometries of pipe to be joined in accordance with the welding technique of the present invention.
FIG. 4 is a perspective view showing the structure of a second electrode geometry which can be used to weld in accordance with the present invention.
FIG. 5 is a schematic perspective view showing a joint and welding equipment assembly which can be used to weld in accordance with the present invention.
FIGS. 6A and 6B are graphs showing the axial and hoop residual stresses respectively as measured on the inside diameter of Type 304 stainless steel 4-inch-diameter pipe butt girth welded in accordance with the present invention.
FIGS. 7A and 7B are graphs showing the axial and hoop residual stresses respectively as measured on the inside diameter of Type 347 stainless steel 4-inch-diameter pipe butt girth welded in accordance with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The welding equipment which is preferably used to carry out the process of the present invention comprises a gas tungsten arc welding system with mechanized torch movement. The blade of the tungsten welding electrode has a non-circular cross section. However, it is believed that the use of a flat tungsten electrode is not necessary to practice the present invention.
In accordance with one weld joint geometry (see FIG. 1C) which is useful in practice of the present invention, the groove between pipes 2 and 4 preferably has an acute angle of <6° and is filled with weld material 6 having a reduced width which requires less heat to achieve fusion. The result is a heat affected zone (HAZ) which in narrower than that produced by "narrow-groove" welding, as seen in FIG. 1B.
Preferably, the process of the present invention employs a tungsten electrode having a non-circular blade cross section. In particular, the blade cross section has an elongated dimension which is oriented parallel to the length of the weld joint and a shortened dimension which is oriented perpendicular to the length of the joint, e.g., a cylinder having a generally rectangular cross section. Preferably, the blade is cut or stamped from a flat sheet material, e.g., tungsten alloy sheet stock. The blade can be cut in the shape of a triangle (preferably isosceles) or a strip having parallel straight sides and a pointed tip at one end.
The thin electrode geometry provides an electrode having a dimension (i.e., the width) which is less than the diameter of a circular cylindrical electrode of equal cross-sectional area. This thinner dimension and its orientation enables the electrode to enter thin grooves which a circular cylindrical electrode is too wide to enter. Accordingly, the width of the joint to be welded can be made significantly smaller than is the case were a circular cylindrical electrode to be used. Further, the use of a noncylindrical, thin electrode allows the weld heat input to be significantly reduced for each pass, and therefore the size and sensitization of the heat affected zone is correspondingly reduced.
The elongated-cross section electrode used in the welding process of the invention is basically not limited in how thin it can be, and therefore how thin the weld joint can be, as long as there is clearance to the walls of the joint for forward travel. One embodiment of a flat tungsten alloy electrode which can be utilized to practice the invention has the geometry shown in FIGS. 2A-2C. Electrode 10 comprises a circular cylindrical shank 10a, a non-circular cylindrical blade 10b and a tip 10c. Blade 10b is optionally covered with an insulating coating. All sharp corners are radiused to prevent arcing. The cross section of blade 10b preferably has the shape of a rectangle with rounded corners. Preferably, the ratio of the length to the width of the rectangle is at least 1.5:1.
Another embodiment of a flat tungsten alloy electrode which can be utilized to practice the invention has the geometry shown in FIG. 4. The electrode comprises a flat generally triangular blade 18 stamped or cut from tungsten alloy sheet. An exemplary thickness of the tungsten alloy sheet is 30 mils. Optionally the triangular shape of the blade may depart from being strictly isosceles by narrowing the tip 18c at an increased rate.
As depicted in FIG. 4, blade 18 comprises a base 18a, a body 18b and a tip 18c. The base 18a is clamped or otherwise held by an electrode holder 20. Electrode holder 20 is preferably made of a conductive, oxidation-resistant material such as copper alloy (e.g., beryllium copper alloy), optionally electroplated with silver or nickel. The electrode holder preferably takes the form of a T-shaped metal body,, comprising a shank 20a and a crosspiece 20b. Shank 20a is connected to a conventional welding torch 14. The crosspiece 20b has a longitudinal slot shaped for receiving the blade base 18a with sufficient play to allow easy insertion and removal. The blade base 18a is held securely in the crosspiece slot by tightening a pair of set screws 22 in a corresponding pair of threaded holes formed in the crosspiece. The blade can be readily removed from the holder after the screws have been loosened. This allows easy replacement of a damaged electrode blade. Also interchangeable electrode blades having different dimensions can be selectively installed depending on the specific application. Alternatively, instead of using screws, the blade could be secured in the holder by brazing to create a monolithic blade assembly, i.e., the blade would not be readily replaceable.
The blade body 18b is preferably covered with an insulating coating, e.g., Al 2 O 3 or Y 2 O 3 , to prevent arcing to the welding groove sidewalls. Also, all rough edges on the stamped or cut blade are deburred to prevent arcing. In accordance with the preferred embodiment, the flat triangular blade incorporates one or more insulating stand-offs 24. Each insulating stand-off protrudes on both flat sides of the electrode blade beyond the plane of the blade surface. These stand-offs serve to maintain a minimum gap between the side walls of the welding groove and the flat sides of the electrode blade, thus preventing scratching or excessive wear of the ceramic coating during electrode travel in the welding groove. A sufficiently deep scratch on the coated surface of the blade will remove ceramic coating 12, leaving the blade susceptible to arcing along the uncoated locus.
A preferred embodiment of a groove geometry of a pipe 2 to be joined using the welding technique of the present invention is depicted in FIG. 3A. The pipe has a wall thickness t. The end face of the pipe comprises a land 2a, which is an annular radial surface extending outward from the inner circumference of the pipe, and a beveled surface 2b, which is a conical surface extending radially outward at an angle θ relative to the radial plane. In accordance with the present invention, θ is preferably <6°. A radiused extension surface 2c connects the outer periphery of land 2a with the inner periphery of beveled surface 2b. Extension surface 2c has a radius R. The height of land 2a is designated by h 1 ; the height of extension 2c is designated by h 2 .
The process of the present invention was successfully applied on 4-inch-diameter pipes made of Type 304, 316 and 347 stainless steel in the horizontal position. The 4-inch-diam. pipe had a wall thickness t=0.250 inch. For the purpose of test welding only, the bevel angle θ was selected to be equal to one of the following: 0°, 2°, 3°, 4° and 5°. The land height h 1 was varied from 0.025 to 0.050 inch; the extension radius R was varied from 0.032 to 0.062 inch.
In accordance with an alternative preferred embodiment of the groove geometry, the radiused land extension is replaced by a 45° angle transition 2d, as shown in FIG. 3B.
During welding, two pipes 2 and 4 are placed end to end in a horizontal position with a groove 8 therebetween, as shown in FIG. 5. A consumable ring-shaped insert 16 was placed between the lands of opposing pipe ends at the root of groove 8 to compensate for any radial mismatch of the lands. During the first (root) pass, the groove between pipes to be joined must be bridged. The lands and the consumable insert (optional) provide material which is fused together to form the weld root. After the root pass, a hot (second) pass is made, followed by a number of filler passes and one or more cap passes.
The optional insert may, but need not have the same composition as the filler wire. During welding development, inserts made of Type 308L or Type 347 stainless steel were used. Inserts having different cross sections were tried, including the following cross sections which proved to be satisfactory: 0.032×0.055 inch, 0.070×0.120 inch 0.090×0.125 inch, 0.037×0.120 inch and 0.050×0.125 inch.
The use of a welding gas with a lower electrical resistance in the ionized state in the welding process, such as a blend of argon and hydrogen and/or helium, rather than pure argon, allows the arc length (between the end of the electrode and the bottom of the weld joint) to be reduced, ensuring that the arc does not transfer to the walls of the joint which are closer to the electrode than is the case in other welding processes. The preferred gas blends are hotter (ionize to a higher temperature), and allow the specific heat input rate to be maximized to effect the most benefit from the fast cap pass speed. Typical previous use of these hot gas blends is to improve welding production without defects, and not to improve the residual stress state as described herein. An alternate method specified in the welding process to prevent the arc from transferring to the walls of the joint is to coat the surface of the electrode, except for the tip where the arc is intended to be transferred, with a material such as a ceramic having a greater resistance to ionize the welding gas blend. This provision helps to ensure that the edges (geometric discontinuities) of the electrode along its length are not arc transfer locations which are more favorable than the electrode tip. This method also eliminates the need to insert an electrically insulating gas cup extension into the joint, as is practiced in some other wider joint welding processes.
In accordance with the low residual stress welding process, the weld beads are deposited inside the groove using the thin elongated tungsten alloy electrode to melt the filler wire fed into the groove. The electrode fits inside groove 8 with clearance between the electrode and the sidewalls as shown in FIG. 5. Electrode blade 18 is electrically coupled to a welding torch 14. The flat electrode in conjunction with the small bevel angle and selected welding parameters produce a very thin weld joint, as shown in FIG. 1C.
The very thin weld joint allows the two surfaces being joined to be in closer proximity to each other. As a result of this closeness, both surfaces are simultaneously wetted by a smaller molten weld pool with a significantly lower heat input rate (i.e., improved thermal efficiency) than is otherwise possible. This reduction in heat input per weld pass to the deposited filler material and base materials being welded allows the size and temperature of the heat affected zone (HAZ) adjacent to the fused zone to be significantly reduced, with the benefit of a corresponding reduction in SCC sensitivity of susceptible materials. As a result, the temperature gradient through the thickness of the component being welded is much steeper, since the gradient is controlled by the relatively constant high temperature of the molten metal, and the reduced low temperature of the near surface of the component (also known as the "root" or first pass of the weld). The steeper temperature gradient through the component which is achieved with the very thin weld joint also leads to the benefit of generating a less tensile or, preferably, a compressive residual stress state at the root of the weld. This improved stress state also leads to a reduction in SCC sensitivity of susceptible materials. The combined effects of the reduced thermal sensitization (i.e., carbide precipitation) in the heat affected zones and of the improved stress state at the root of the weld provide a significant increase in SCC resistance of a welded joint exposed to an aggressive environment.
Another related benefit of the reduced heat input, size and temperature of the heat affected zone in accordance with the low residual stress welding process is a reduction in or elimination of grain growth during welding. Significant grain growth in the heat affected zone and the corresponding thermal sensitization in this area leads to the "knife line attack" form of SCC in materials which are otherwise resistant to SCC, such as the stabilized grades of austenitic stainless steel.
The improved residual stress state at the root of a joint made by the low residual stress welding process, relative to the conventional joint welded with a wider groove and a circular cylindrical electrode, is generated by a stress reversal during the welding process. During the welding, the hot, weakened heat affected zone and recently solidified weld metal are plastically compressed due to their thermal expansion relative to the cooler and stronger surrounding material. Upon cooling, this compressed zone contracts against the surrounding material and is put in a state of tensile residual stress. The contraction and corresponding tensile stresses are balanced by the surrounding material, in particular the weld root, going to the desired state of less tensile or to a more desirable compressive stress. The degree of stress improvement depends on the particular welding process parameters used. In the low residual stress welding process, a key factor in making the welding process effective in generating significantly reduced heat affected zone sensitization and root tensile residual stresses without water cooling (external heat sinking) of the component being welded is the very low heat input capability of the process (and corresponding internal heat sinking), made possible by the very thin joint geometry and in turn by the thin, non-circular welding electrode shape.
Another benefit of the reduction in the tensile residual stresses at the root of a joint made with the low residual stress welding process is a decrease in the susceptibility of materials exposed in an irradiation environment to the mechanism of irradiation-assisted stress corrosion cracking (IASCC). This beneficial effect arises due to the retardation of diffusion of the detrimental elements to internal interfaces, which is assisted by the influence of higher tensile residual stresses.
The passive heat sink welding process of the present invention improves upon the above-described low residual stress welding process. The process of the invention has application on all piping and other types of components to be welded. In accordance with that process, the conductive self-cooling effects of the base metal alone, when combined with a very high welding torch travel speed, are capable of significantly improving the residual stress of component weld joints without the need for water or other supplementary cooling of the component during the welding. Due to the uniquely high torch travel speeds (>10 inches/min) used, the inventive process has been made effective even for thin (e.g., 0.25 and 0.375 inch thick) wall material with inherently little self-heat sinking capacity. The high torch travel speeds are in turn made possible due to the use of welding gases having high dissociation/ionization temperatures, including inert gas blends comprising hydrogen and/or helium.
The significant through-wall temperature gradient produced by the high torch travel speeds is achieved due to the combined high heating efficiency, the high heating and cooling rates, the thin joint design utilized and the corresponding small size of each weld pass. The required temperature gradient and thermal stress, and the resulting improved residual stress distribution, are subsequently established through the thickness of the material being welded. The final levels of residual stresses are established as the outer passes, especially the cap passes, of the joint are completed.
The level of welding current is adjusted so that for a limited range of torch travel speed, the desired temperature distribution is established across the wall thickness. The requirement is to have a sufficient portion of the wall thickness hot enough so that its thermal expansion will cause it to be deformed in compression (while hot and weakened) by the balancing forces of the colder part of the wall, and subsequently to go into tension after cooling to ambient temperature. In order to maintain the force balance across the wall after cooling, the part of the wall which was in tension as the torch passed then goes into compression, which is the desired result.
In order for the passive heat sink welding process of the invention to be most effective, it is desirable that the welding parameters used to fill the joint before the very fast cap passes are applied be of a low heat input/low distortion type so that the level of tensile residual stresses at the root of the joint is initially as low as practical. In this respect, use of the low residual stress welding process before the passive heat sink welding process would be very beneficial as the base method for new weld applications. Existing, standard type welds which need residual stress mitigation are expected to benefit from subsequent application of the passive heat sink welding process as well, especially for welds joining thin materials. By applying a heat treatment during the cap passes, i.e., without fusing of the underlying material, the residual stress state can be mitigated to a reduced tensile stress substantially less than the yield strength or, preferably, to a compressive state.
The degree of stress mitigation depends on the thermal and mechanical properties of the material as a function of temperature, as well as on the thickness of the material and the general welding parameters. The unique feature of the passive heat sink welding process in accordance with the invention is that the tensile residual stresses are significantly reduced or eliminated by intentional control of the final welding specific heat input rate (per unit area of the weld joint outside surface) to a relatively high value, applied for a relatively short time, and in turn generating the typical magnitude of the through-wall temperature gradient (from above the melting temperature of the metal at the final surface to temperatures near ambient at the initial surface) normally achieved only with supplemental cooling, which is generally flowing water.
The specific heat input rate is maximized as desired by using a hot welding gas, and especially by moving the torch at the uniquely high forward travel speeds during the final cap pass or passes. Secondary adjustments to the heat input rate are controlled with the welding current and/or voltage. The high torch travel speed in accordance with the teaching of the invention (namely, >10 inches/min) is faster than the speeds conventionally used for electric arc welding in general and gas tungsten arc welding in particular by at least a factor of three, and has previously been considered unacceptable for sound welding practice. The invention utilizes the effect of extremely high torch travel speeds to significantly redistribute and optimize the residual stresses. Nevertheless, testing has demonstrated that the passive heat sink welding process is both effective for stress mitigation and suitable for various types of mechanized applications without any sacrifice in weld structural integrity.
Some of the welding process parameters which control the thermal efficiency of the process include the arc gas composition, the torch travel speed, and the arc current and current pulsing values. These and other parameters have been selected in order to further the minimization of the heat affected zone and the root tensile residual stress. Measurements of the pipe diameter and axial length revealed that shrinkage was reduced, resulting in less tensile stress, if not compressive stress at the near surface of the weld joint.
Different inert gas mixtures were tested as the shield gas. The mixture of argon with either hydrogen or helium increases the temperature of the arc, causing the weld puddle to wet the substrate more quickly. Because of the high energy density, the skin of the substrate is heated quickly, leaving less time for the conduction of heat below the skin. This produces a thinner heat affected zone than is conventionally known. The addition of hydrogen or helium also shortens the arc, so that less clearance to the side walls is needed.
Different torch travel speeds were tried during test welding. The root pass was made at speeds of 5.0-10.0 inches/min. The torch travel speed for the hot pass varied between 5.5 and 16.5 inches/min. The cap passes were made at speeds of 10 inches/min or greater. Satisfactory welds, i.e., welds with reduced tensile stress substantially less than the yield strength or with compressive stress at the near surface, were obtained using torch travel speeds of 16.5, 20 and 25 inches/min for the cap pass or passes.
X-ray diffraction measurements on the inside surface of welds made in accordance with the present invention have shown that a substantial stress improvement has been achieved, with all of the region of interest near and in the weld root being in a state of compressive stress. This can be seen in FIGS. 6A and 6B and in FIGS. 7A and 7B, which respectively show the axial and hoop residual stresses as measured on the inside diameter of Type 347 and Type 304 stainless steel 4-inch-diameter pipe butt girth welded in accordance with the present invention. The X-ray diffraction results were confirmed by tests performed in accordance with ASTM G36-73, Standard Recommended Practice for Performing Stress Corrosion Cracking Tests in a Boiling Magnesium Chloride Solution.
In accordance with a further aspect of the invention, the welding torch is oscillated laterally during the cap pass or passes. The purpose of lateral torch oscillation is to spread the heat on the far surface of the pipe in a manner that produces a compressive stress state over a wider axial length on the near surface, thereby reducing the concentration of bending moment applied across the weld root and mitigating fine circumferential cracking along the fusion line on either side of the weld. The lateral oscillation can be carried out mechanically by moving the head back and forth by motor drive or electromagnetically by applying an oscillating electromagnetic field which causes the arc to deflect from side to side.
In accordance with a further alternative, two or more beads can be laid side by side in separate cap passes. The provision of multiple cap passes laterally distributes heat to both sides of the weld centerline, again for the purpose of reducing the concentration of bending moment applied across the weld root.
The foregoing process has been disclosed for the purpose of illustration. Variations and modifications of the disclosed process will be apparent to practitioners skilled in the art of welding. For example, the current and voltage supplied to the electrode can be adjusted as necessary in dependence on the torch travel speed and the joint geometry to achieve the desired compressive stress state. All such variations and modifications which do not depart from the concept of the present invention are intended to be encompassed by the claims set forth hereinafter.
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A process for providing a significant improvement in the detrimental tensile residual stress condition on the root side of welds, especially on the inside wall of piping welds. The method uses a high welding torch travel speed (>10 inches/min), especially on the last one or two cap passes. The process relies on the limited thermal heat sink capability of the pipe wall and nearly completed weld joint itself to generate a significant through-wall temperature gradient, and therefore a sufficient through-wall stress gradient during the welding. This stress gradient results in metal plasticity and permanent strains, and therefore a reduction in the magnitude of the final residual stress or, preferably as conditions allow, a reversal in the direction of the stresses from tensile to compressive. The method can be used as a welding process or as a heat treatment. In the case of heat treatment, the far surface of the weld joint is heated without fusion of the material making up the far surface.
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[0001] This claims the benefit of German Patent Application No 103 26 431.0-55, filed Jun. 10, 2003 and hereby incorporated by reference herein.
[0002] The present invention is directed to a device and to a method for determining the position of objects in the surroundings of a motor vehicle.
BACKGROUND
[0003] Due to the tremendous increase in traffic density over the last decades and the elevated risk of accidents associated therewith, systems for improving vehicle safety have gained in importance.
[0004] The focus of engineering and development has been, in particular, in the area of safety systems, which are activated in the event of a collision with an obstacle or another vehicle. In the meantime, airbags and seat-belt tighteners have become standard safety equipment in virtually every production vehicle. In order for these components to be optimally effective, first measures are advantageously initiated, not only at the time of or immediately following the moment of impact, but already beforehand. Such measures include, for example, resetting the electronic control of a seat-belt tightener or airbag to a state of heightened readiness.
[0005] To this end, it is necessary, however, to reliably predict the imminent accident event already before the instant of impact.
[0006] Therefore, information must be obtained on the positions and relative velocities of objects in the relatively near vehicle surroundings.
[0007] Moreover, this information can be used to realize additional functionalities, such as a park distance control, a monitoring of the dead angle, as well as a stop-and-go assistant, in addition to an electronic distance control, such as an adaptive cruise control (ACC) in the vehicle.
[0008] One possible approach for monitoring the vehicle surroundings provides for using radar sensors.
[0009] Thus, for example, the SAE paper 1999-01-1239 “ Radar Based Near Distance Sensing Device for Automotive Application”, describes a surrounding-field sensor system based on the use of radars. The system described in the mentioned publication employs two radar sensors, which work in a frequency range of 24 GHz and cover the area in front of the vehicle front end and, respectively, behind the rear-end section. Since the radar modules used in the described publication do not exhibit any directivity characteristic, the precise position of a sensed object is determined from the measured distances using triangulation. This requires that an object, whose precise position is to be determined, be situated in the overlap region of at least two radar sensors. In this context, the area in which an object can be detected by a radar sensor, depends on the so-called “radar cross-section” (RCS), which can be described as the reflectivity of an object for radar waves.
[0010] However, there are some disadvantages associated with the use of triangulation for determining precise positions: Inexact distance determinations greatly affect the values ascertained for the angle and, thus, for the position. To minimize this error, the radar sensors would have to be positioned at a distance from one another that is on the order of magnitude of the distance of the sensed object from the vehicle. However, this is not feasible in a vehicle application, since the maximum distance between the radar sensors is limited by the width of the vehicle.
[0011] Furthermore, a necessary assumption of the triangulation method is that the objects in the typical automobile surroundings are small or punctiform. This is no longer a reasonable assumption, since the objects being considered are more likely to have sizable dimensions (other vehicles, trucks, pedestrians).
[0012] Moreover, there is the risk when applying the triangulation method, that two objects, which are each at the same distance from a radar sensor, are interpreted as one single object, which is then erroneously localized between the two real objects (so-called ghost target).
[0013] To overcome some of the drawbacks discussed above, the German Application DE 199 49 409 A1 proposes observing the time characteristic of the positions of the sensed objects (so-called tracking). However, the method proposed in the mentioned publication entails substantial computational expenditure and, thus, an unacceptable processing time, particularly for time-critical applications, such as precrash sensor analysis.
[0014] Moreover, a tracking method yields usable results only in the context of an approximately constant motion of the objects being tracked, without too great dynamic changes occurring. It is precisely in critical driving situations, where reliable detection of objects in the relatively near vehicle surroundings is of decisive importance, that extremely dynamic action and, thus, qualitatively inferior results of a tracking method are to be expected.
SUMMARY OF THE INVENTION
[0015] An object of the present invention is, therefore, to provide a device and a method which will ensure a reliable and rapid detection of objects in the vehicle surroundings.
[0016] In accordance with the method of the present invention for sensing objects in the areas surrounding vehicles, positional information pertaining to the objects in the vehicle surroundings is derived on the basis of a comparison of input values, supplied by sensors, with data sets stored in a memory unit. The input values include distance data and Doppler velocities, for example. Doppler velocities are the velocities of an object in relation to a sensor that are ascertained by the sensor itself from a Doppler measurement, and output by the sensor. The data stored in the memory unit are reference data sets which represent the objects in a defined spatial region in the vehicle surround, with their exact positions. To precisely determine the position of an object detected by the sensors, the input values supplied by the sensors are compared within the framework of a classification, to the reference data sets. On the basis of the thus determined position of the object in relation to the vehicle, a decision may be made as to whether a sensed object is located within an area in which a collision with the object is to be expected; in particular, it is possible to differentiate between an obstacle that is expected to be passed by or one that is expected to be hit.
[0017] The method is continuously repeated in successive measuring cycles, at selectable intervals.
[0018] Various advantages are derived from the classification, such as a high recognition rate, i.e., real objects in the vehicle surroundings are reliably detected. In this context, objects rapidly approaching one side of the vehicle are also reliably detected.
[0019] Moreover, by doing without tracking algorithms, the positional determination in accordance with the method of the present invention is able to be carried out much more rapidly than would be possible using a tracking method.
[0020] The computational expenditure associated with the conventional methods, such as triangulation or tracking, increases considerably with the number of sensors used. In contrast, the use of a plurality of sensors in conjunction with a classification, entails an only slight increase in computational expenditure, since, for the most part, a classification is a comparison of data sets that is able to be quickly performed.
[0021] In addition, the method according to the present invention enables punctiform, as well as sizable, and weakly reflecting objects, such as pedestrians, to be detected with adequate certainty.
[0022] Typically, the input values supplied by the sensors merely provide information on recognized targets along with their particular distances and velocities, without allocating recognized targets to real objects. In one first advantageous variant of the present invention, real objects in the vehicle surroundings are ascertained from these input values, and their distance data are determined. In the process, it is also advantageous to consider the velocity values of the detected targets, furnished by the sensors; on the one hand, this makes it possible to improve the recognition of relevant objects and, on the other hand, to suppress errors resulting, for example, from distance measurements made by various sensors to different objects being erroneously interpreted as measurements to one single object (so-called ghost targets).
[0023] Moreover, it is beneficial to correct any signal dropouts in the measured values by averaging preceding and subsequent values. In this context, the number of values to be considered (the so-called filter mask) may be variably selected. This clearly improves the quality of the data to be processed and thus the recognition rate of relevant objects.
[0024] Another advantageous refinement of the method according to the present invention provides for determining the relative velocities between the sensed objects and the vehicle. The thus obtained relative velocities may be utilized when applying the method according to the present invention, as input information for a precrash sensor system, in order to predict a potentially imminent collision with an object and, if indicated, to initiate appropriate countermeasures.
[0025] The relative velocities may be determined in two ways.
[0026] A first possibility for calculating the relative velocity provides for analyzing the successively measured distance data to an object. To this end, for example, the distance data stored at a specific point in time in the FIFO (first in—first out memory) of a sensor are analyzed, and the relative velocities obtained in this manner for this point in time are averaged. In a subsequent step, the average value of the thus obtained, averaged relative velocities is formed for a specific, defined time period. The relative velocities obtained in this manner are stored in another FIFO.
[0027] An alternative to this manner of determining the relative velocity provides for first reading out the Doppler velocities for an object measured by the sensors. These Doppler velocities are averaged for a specific period of time and the thus obtained average values for the considered periods of time are stored in an FIFO memory.
[0028] In accordance with one advantageous refinement of the method of the present invention, on the basis of the quantities ascertained by the sensors, a delimited region is defined in the vehicle surroundings in which the objects to be considered are situated.
[0029] For this purpose, the so-called “critical distance” is initially defined. It depends on the calculated relative velocity between an object and the vehicle, the early-warning time for the safety-related components of the vehicle, as well as on the update rate of the input values, and is used as a basis for calculating the region to be considered.
[0030] To calculate the region being considered, for example in front of a vehicle, the following method steps are carried out in particular:
[0031] When the smallest measured distance min(r ji ) is smaller than the critical distance, then the upper threshold of the region to be considered is defined as min(r ji ), otherwise the process is terminated—no object is situated within the critical distance. In this context, r ji is the distance of sensor j from object i.
[0032] The lower threshold of the region to be considered is derived from the crossings of the circles of radii r ji with the defined, lateral limits of the area to be considered. In the case that the area considered is an area in front of a vehicle, then the lateral limits essentially correspond to those lines which define the width of the vehicle.
[0033] When the thus ascertained lower threshold is below a specific minimum threshold, then this minimum threshold is defined as the lower threshold. The minimum threshold may correspond, for example, to the smallest measurable distance of the sensors.
[0034] Defining the region to be considered makes it advantageously possible to distinguish between the relevant and irrelevant objects sensed by the sensors. It is thus ensured that no computational time is used to calculate the precise position of irrelevant objects and that the full capacity of a processor that is used may be used to determine the precise position of relevant objects.
[0035] Moreover, it is advantageous to take precautions for cases when it is not possible to ascertain any positional data using the classification procedure. In such cases, the result of the classification reads “ZERO”. If the classification yields the result “ZERO” multiple times in succession, then the last valid result is maintained for an adjustable number of measuring cycles. However, this result is only output when the number of same or similar results of the preceding measuring cycles exceeds a number that is settable in advance. It is thus ensured that a correct result is output and not, for instance, the result of an already erroneous last measurement.
[0036] The described method may be advantageously implemented by a device, which may be installed as original equipment in vehicles or offered as a supplementary-equipment set. The device according to the present invention has a plurality of sensors, as well as an analyzing unit, for example a processor integrated in the vehicle having inputs and outputs, as well as a memory unit. The classification and thus the exact positional determination of the relevant objects is undertaken by the processor on the basis of a comparison with reference data sets stored in the memory unit. The device according to the present invention may be used both in the front-end section, as well as in the rear section of a vehicle.
[0037] In this context, radar sensors, for example, constitute an advantageous choice for the sensors. This class of sensors supplies high-quality data even under the most diversified weather and illumination conditions. In the meantime, suitable radar sensors have become commercially available at reasonable prices; they are offered by the firm M/A-COM, for example. Optical sensors may be used as an alternative to radar sensors or to supplement the same. In this case, so-called closing velocity sensors (CV) offer some advantages.
[0038] A CV sensor emits coded laser light which is reflected by objects in the sensing range. From the reflected signal, information can be derived on the distance and state of motion of an object, similarly to the manner in which information is obtained from a radar signal. Besides these primary functions, other possible uses arise from the power spectrum of the sensor. Thus, for example, it is conceivable to use the CV sensor as a rain or road-condition sensor.
[0039] To enhance the safety of operation of the device, it is beneficial to provide additional means to monitor the reliability performance of the sensors, i.e., detect a possible sensor failure and warn the driver, i.e., deactivate the device, to prevent false activation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] One possible embodiment of the present invention is explained in detail in the following with reference to the drawings, whose figures show:
[0041] FIG. 1 a block diagram of the method according to the present invention;
[0042] FIG. 2 a detailed representation of the geometrical relationships in the area being considered for a classification.
DETAILED DESCRIPTION
[0043] FIG. 1 shows a block diagram, to clarify the functioning of a device in which the method according to the present invention may be implemented. Within their sensing range, sensors 1 determine distances and relative velocities of objects and transmit the same to input filter 2 . In this context, input filter 2 is used, on the one hand, to equalize any signal drop-outs in the sensor data in an averaging operation over a plurality of measuring cycles, and, on the other hand, on the basis of the distances measured by the sensors, and the velocities, to generate target lists containing the individual target objects identified in the sensing range of the sensor, and to make it possible to differentiate among various objects. The information acquired in input filter 2 is subsequently fed to the unit for calculating relative velocity 3 . In this unit, on the basis of the information acquired from input filter 2 , the relative velocities between the detected objects and the vehicle are determined. Together with the distance values, which are determined for the individual objects by input filter 2 , this information is further processed in the downstream unit to determine relevant area 4 . Here, it is established in accordance with the above described method, which objects are to be considered as relevant and should thus be the subject of subsequent classification 5 . An important result of classification 5 is the determination of the exact positions of relevant objects in front of the vehicle. This is accomplished on the basis of a comparison of the measured values with reference values stored in a database, and by selecting the data set which yields the fewest deviations from the data set determined on the basis of the measurements.
[0044] In the last step of the method, any error measurements are corrected or suppressed by output filter 6 in that output filter 6 maintains plausible results from the preceding measuring cycles.
[0045] The partitioning of tasks into individual components, selected in the exemplary embodiment presented here, is to be viewed as an exemplary realization; it is, of course, likewise possible to combine parts of the method into functional units, in a software implementation, for example.
[0046] Classification 5 is explained in greater detail on the basis of subsequent FIG. 2 . The distance of an object from the front of vehicle s i , its lateral offset from sensor b i , as well as distance r i of the object from sensor i, form a right-angled triangle. Thus it holds that:
i 2 =r i 2 −S i 2
[0047] In the following, the determination of the exact position of an individual object 10 is considered: For object 10 having known distance r i to sensor i, individual b i are successively determined for different S i , which are within the delimited region in the vehicle surroundings. In the process, S i is progressively varied within the limits obtained from the determination of the area to be considered. The thus obtained sets of b i for sensor i may be considered as components of a vector. This procedure is repeated for all sensors i. At this point, the thus obtained vectors are compared in a subsequent step to reference vectors stored in the database. To determine lateral offset b of object 10 in front of the vehicle, that vector is selected from the database which deviates the least from the vector determined from the measured data. Lateral offset b of object 10 in front of the vehicle may be quickly determined in this manner. In the process, the speed of the classification may be optimized by suitably selecting the step size for S i .
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A method for sensing objects in the surrounding field of vehicles, input values being determined by a plurality of sensors, and positional information pertaining to the objects being derived on the basis of a comparison with stored data, as well as a device for implementing the method.
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[0001] This is a divisional of U.S. application Ser. No. 10/134,780, filed Apr. 29, 2002, the entire disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates generally to peer-to-peer protocols, and more particularly to security framework infrastructures for peer-to-peer protocols.
BACKGROUND OF THE INVENTION
[0003] Peer-to-peer (P2P) communication, and in fact all types of communication, depend on the possibility of establishing valid connections between selected entities. However, entities may have one or several addresses that may vary because the entities move in the network, because the topology changes, or because an address lease cannot be renewed. A classic architectural solution to this addressing problem is thus to assign to each entity a stable name, and to “resolve” this name to a current address when a connection is needed. This name to address translation must be very robust, and it must also allow for easy and fast updates.
[0004] To increase the likelihood that an entity's address may be found by those seeking to connect to it, many peer-to-peer protocols, including the Peer Name Resolution Protocol (PNRP), allow entities to publish their address through various mechanisms. Some protocols also allow a client to acquire knowledge of other entities' addresses through the processing of requests from others in the network. Indeed, it is this acquisition of address knowledge that enables successful operation of peer-to-peer networks. That is, the better the information about other peers in the network, the greater the likelihood that a search for a particular resource will converge.
[0005] However, without a robust security infrastructure underlying the peer-to-peer protocol, malicious entities can easily disrupt the ability for such peer-to-peer systems to converge. Such disruptions may be caused, for example, by an entity that engages in identity theft. In such an identity theft attack on the peer-to-peer network, a malicious node publishes address information for identifications (IDs) with which it does not have an authorized relationship, i.e. it is neither the owner nor a group member, etc. A malicious entity could also intercept and/or respond first before the good node responds, thus appearing to be the good node.
[0006] Commonly, P2P network attacks may attempt to disrupt or exhaust node or network resources. In PNRP, a malicious entity could also obstruct PNRP resolution by flooding the network with bad information so that other entities in the network would tend to forward requests to nonexistent nodes (which would adversely affect the convergence of searches), or to nodes controlled by the attacker. PNRP's name resolution ability could also be degraded by modifying the RESOLVE packet used to discover resources before forwarding it to a next node, or by sending an invalid RESPONSE to back to the requester that generated the RESOLVE packet. A malicious entity could also attempt to disrupt the operation of the peer-to-peer network by trying to ensure that searches will not converge by, for example, instead of forwarding the search to a node in its cache that is closer to the ID to aid in the search convergence, forwarding the search to a node that is further away from the requested ID. Alternatively, the malicious entity could simply not respond to the search request at all. The PNRP resolution could be further hampered by a malicious node sending an invalid BYE message on behalf of a valid ID. As a result, other nodes in the cloud will remove this valid ID from their cache, decreasing the number of valid nodes stored therein.
[0007] While simply validating address certificates may prevent the identity theft problem, such is ineffective against an attack that impedes PNRP resolution. An attacker can continue to generate verifiable address certificates (or have them pre-generated) and flood the corresponding IDs in the peer-to-peer cloud. If any of the nodes attempts to verify ownership of the ID, the attacker would be able to verify that it is the owner for the flooded IDs because, in fact, it is. However, if the attacker manages to generate enough IDs it can bring most of the peer-to-peer searches to one of the nodes it controls. Once a malicious node brings the search to controlled node, the attacker fairly controls and directs the operation of the network.
[0008] A malicious node may also attempt a denial of service (DoS) attack. When a P2P node changes, it may publish its new information to other network nodes. If all the nodes that learn about the new node records try to perform an ID ownership check, a storm of network activity against the advertised ID owner will occur. Exploiting this weakness, an attacker could mount an internet protocol (IP) DoS attack against a certain target by making that target very popular. For example, if a malicious entity advertises an Internet Website IP address as the updated node's ID IP, all the nodes in the peer-to-peer network that receive this advertised IP will try to connect to that IP to verify the authenticity of the record. Of course, the Website's server will not be able to verify ownership of the ID because the attacker generated this information. However, the damage has already been done. That is, the attacker convinced a good part of the peer-to-peer community to flood the IP address with validation requests and may have effectively shut it down.
[0009] Another type of DoS attack that overwhelms a node or a cloud by exhausting one or more resources occurs when a malicious node sends a large volume of invalid/valid peer address certificates (PACs) to a single node (e.g. by using FLOOD/RESOLVE/SOLICIT packets). The node that receives these PACs will consume all its CPU trying to verify all of the PACs. Similarly, by sending invalid FLOOD/RESOLVE packets, a malicious node will achieve packet multiplication within the cloud. That is, the malicious node can consume network bandwidth for a PNRP cloud using a small number of such packets because the node to which these packets are sent will respond by sending additional packets. Network bandwidth multiplication can also be achieved by a malicious node by sending bogus REQUEST messages to which good nodes will respond by FLOODing the PACs, which are of a larger size than the REQUEST.
[0010] A malicious node can also perpetrate an attack in the PNRP cloud by obstructing the initial node synch up. That is, to join the PNRP cloud a node tries to connect to one of the nodes already present in the PNRP cloud. If the node tries to connect to the malicious node, it can be completely controlled by that malicious node. Further, a malicious node can send invalid REQUEST packets when two good nodes are involved in the synchronization process. This is a type of DoS attack that will hamper the synch up. Because the invalid REQUEST packets generate FLOOD messages in response, initial node synch up may be hindered.
[0011] There exists a need in the art, therefore, for security mechanisms that will ensure the integrity of the P2P cloud by preventing or mitigating the effect of such attacks.
BRIEF SUMMARY OF THE INVENTION
[0012] The inventive concepts disclosed in this application involve a new and improved method for inhibiting a malicious node's ability to disrupt normal operation of a peer-to-peer network. Specifically, the present invention presents methods to address various types of attacks that may be launched by a malicious node, including identity theft attacks, denial of service attacks, attacks that merely attempt to hamper the address resolution in the peer-to-peer network, as well as attacks that attempt to hamper a new node's ability to join and participate in the peer-to-peer network.
[0013] The security infrastructure and methods presented allow both secure and insecure identities to be used by nodes by making them self-verifying. When necessary or opportunistic, ID ownership is validated by piggybacking the validation on existing messages or, if necessary, by sending a small inquire message. The probability of connecting initially to a malicious node is reduced by randomly selecting the connection node. Further, information from malicious nodes is identified and can be disregarded by maintaining information about prior communications requiring a future response. Denial of service attacks are inhibited by allowing the node to disregard requests when its resource utilization exceeds a predetermined limit. The ability for a malicious node to remove a valid node is reduced by requiring revocation certificates to be signed by the node to be removed.
[0014] In accordance with one embodiment of the present invention, a method of generating a self-verifiable insecure peer address certificate (PAC) that will prevent a malicious node from publishing another node's secure identification in an insecure PAC in the peer-to-peer network is presented. This method comprises the steps of generating an insecure PAC for a resource discoverable in the peer-to-peer network. The resource has a peer-to-peer identification (ID). The method further includes the step of including a uniform resource identifier (URI) in the insecure PAC from which the peer-to-peer ID is derived. Preferably, the URI is in the format “p2p://URI”. The peer-to-peer ID may also be insecure.
[0015] In a further embodiment, a method of opportunistically validating a peer address certificate at a first node in a peer-to-peer network is presented. This first node utilizes a multilevel cache for storage of peer address certificates, and the method comprises the steps of receiving a peer address certificate (PAC) purportedly from a second node and determining the PAC storage level in the multilevel cache. When the PAC is to be stored in one of two lowest cache levels, the method places the PAC in a set aside list, generates an INQUIRE message containing an ID of the PAC to be validated, and transmits the INQUIRE message to the second node. When the PAC is to be stored in an upper cache level other than one of the two lowest cache levels, the method stores the PAC in the upper cache level marked as ‘not validated’. In this case, the PAC will be validated the first time it is used. The method may also request a certificate chain for the PAC.
[0016] In a preferred embodiment, creating of the INQUIRE message comprises the step of generating a transaction ID to be included in the INQUIRE message. When an AUTHORITY message is received from the second node in response to the INQUIRE message, the PAC is removed from the set aside list and is stored in one of the two lowest cache levels. If a certificate chain was requested, the AUTHORITY message is examined to determine if the certificate chain is present and valid. If the AUTHORITY is present and valid, the PAC is stored in the one of the two lowest cache levels, and if not, it is deleted. A transaction ID may also be used in an embodiment of the invention to ensure that the AUTHORITY message is in response to a prior communication.
[0017] In a further embodiment of the present invention, a method of discovering a node in a peer-to-peer network in a manner that reduces the probability of connecting to a malicious node is presented. This method comprises the steps of broadcasting a discovery message in the peer-to-peer network without including any IDs locally registered, receiving a response from a node in the peer-to-peer network, and establishing a peering relationship with the node. In one embodiment, the step of receiving a response from a node comprises the step of receiving a response from at least two nodes in the peer-to-peer network. In this situation, the step of establishing a peering relationship with the node comprises the steps of randomly selecting one of the at least two nodes and establishing a peering relationship with the randomly selected one of the at least two nodes.
[0018] In yet a further embodiment of the present invention, a method of inhibiting a denial of service attack based on a synchronization process in a peer-to-peer network is presented. This method comprises the steps of receiving a SOLICIT message requesting cache synchronization from a first node containing a peer address certificate (PAC), examining the PAC to determine its validity, and dropping the SOLICIT packet when the step of examining the PAC determines that the PAC is not valid. Preferably, when the step of examining the PAC determines that the PAC is valid, the method further comprises the steps of generating a nonce, encrypting the nonce with a first node public key of the first node, generating an ADVERTISE message including the encrypted nonce, and sending the ADVERTISE message to the first node. When a REQUEST message is received from the first node, the method examines the REQUEST message to determine if the first node was able to decrypt the encrypted nonce, and processes the REQUEST message when the first node was able to decrypt the encrypted nonce.
[0019] Preferably, this method further comprises the steps of maintaining connection information specifically identifying the communication with the first node, examining the REQUEST message to ensure that it is specifically related to the ADVERTISE message, and rejecting the REQUEST message when it is not specifically related to the ADVERTISE message. In one embodiment, the step of maintaining connection information specifically identifying the communication with the first node comprises the steps of calculating a first bitpos as the hash of the nonce and the first node's identity, and setting a bit at the first bitpos in a bit vector. When this is done, the step of examining the REQUEST message comprises the steps of extracting the nonce and the first node's identity from the REQUEST message, calculating a second bitpos as the hash of the nonce and the first node's identity, examining the bit vector to determine if it has a bit set corresponding to the second bitpos, and indicating that the REQUEST is not specifically related to the ADVERTISE message when the step of examining the bit vector does not find a bit set corresponding to the second bitpos. Alternatively, the nonce may be used directly as the bitpos. In this case, when the REQUEST is received, the bitpos corresponding to the enclosed nonce is checked. If it is set, this is a valid REQUEST and the bitpos is cleared. Otherwise, this is an invalid REQUEST or replay attack, and the REQUEST is discarded.
[0020] In yet a further embodiment of the present invention, a method of inhibiting a denial of service attack based on a synchronization process in a peer-to-peer network comprises the steps of receiving a REQUEST message purportedly from a first node, determining if the REQUEST message is in response to prior communication with the first node, and rejecting the REQUEST message when the REQUEST message is not in response to prior communication with the first node. Preferably, the step of determining if the REQUEST message is in response to prior communication comprises the steps of extracting a nonce and an identity purportedly of the first node from the REQUEST message, calculating a bitpos as the hash of the nonce and the identity, examining a bit vector to determine if it has a bit set corresponding to the bitpos, and indicating that the REQUEST is not in response to prior communication with the first node when there is no bit set corresponding to the bitpos.
[0021] A method of inhibiting denial of service attacks based on node resource consumption in a peer-to-peer network is also presented. This method comprises the steps of receiving a message from a node in the peer-to-peer network, examining current resource utilization, and rejecting processing of the message when the current resource utilization is above a predetermined level. When a RESOLVE message is received, the step of rejecting processing of the message comprises the step of sending an AUTHORITY message to the first node. This AUTHORITY message contains an indication that the RESOLVE message will not be processed because the current resource utilization too high. When a FLOOD message is received containing a peer address certificate (PAC) and the method determines that the PAC should be stored in one of two lowest cache levels, the step of rejecting processing of the message comprises the step of placing the PAC in a set aside list for later processing. If the method determines that the PAC should be stored in a cache level higher than two lowest cache levels, the step of rejecting processing of the message comprises the step of rejecting the FLOOD message.
[0022] In another embodiment of the present invention, a method of inhibiting denial of service attacks based on node bandwidth consumption in a peer-to-peer network is presented. This method comprises the steps of receiving a request for cache synchronization from a node in the peer-to-peer network, examining a metric indicating a number of cache synchronizations performed in the past, and rejecting processing of the request for cache synchronization when the number of cache synchronizations performed in the past exceeds a predetermined maximum. In a further embodiment, the method examines the metric to determine the number of cache synchronizations performed during a predetermined preceding period of time. In this embodiment the step of rejecting processing of the request comprises the step of rejecting processing of the request for cache synchronization when the number of cache synchronizations performed in the preceding period of time exceeds a predetermined maximum.
[0023] In another embodiment of the present invention, a method of inhibiting a search based DoS attack in a peer-to-peer network comprises the steps of examining cache entries of known peer address certificates to determine appropriate nodes to which to send a resolution request, randomly selecting one of the appropriate nodes, and sending the resolution request to the randomly selected node. In one embodiment the step of randomly selecting one of the appropriate nodes comprises the step of calculating a weighted probability for each of the appropriate nodes based on the distance of the PNRP ID from the target ID. The probability of choosing a specific next hop is then determined as an inverse proportionality to the ID distance between that node and the target node.
[0024] In a further embodiment of the present invention, a method of inhibiting a search based denial of service attack in a peer-to-peer network comprises the steps of receiving a RESPONSE message, determining if the RESPONSE message is in response to a prior RESOLVE message, and rejecting the RESPONSE message when the RESPONSE message is not in response to the prior RESOLVE message. Preferably, the step of determining if the RESPONSE message is in response to a prior RESOLVE message comprises the steps of calculating a bitpos as a hash of information in the RESPONSE message, and examining a bit vector to determine if a bit corresponding to the bitpos is set therein.
[0025] In one embodiment wherein the RESPONSE message contains an address list, the method further comprises the steps of determining if the RESPONSE message has been modified in an attempt to hamper resolution, and rejecting the RESPONSE message when the RESPONSE message has been modified in an attempt to hamper resolution. Preferably the step of determining if the RESPONSE message has been modified in an attempt to hamper resolution comprises the steps of calculating a bitpos as a hash of the address list in the RESPONSE message, and examining a bit vector to determine if a bit corresponding to the bitpos is set therein.
[0026] In another embodiment of the present invention, a method of inhibiting a malicious node from removing a valid node from the peer-to-peer network comprises the steps of receiving a revocation certificate purportedly from the valid node having a peer address certificate (PAC) stored in the receiving node cache, and verifying that the revocation certificate is signed by the valid node.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention. In the drawings:
[0028] FIG. 1 is a block diagram generally illustrating an exemplary computer system on which the present invention resides;
[0029] FIG. 2 is a simplified flow diagram illustrating security aspects of AUTHORITY packet processing in accordance with an embodiment of the present invention;
[0030] FIG. 3 is a simplified communications processing flow diagram illustrating security aspects of a synchronization phase of P2P discovery in accordance with an embodiment of the present invention;
[0031] FIG. 4 is a simplified flow diagram illustrating security aspects of RESOLVE packet processing in accordance with an embodiment of the present invention;
[0032] FIG. 5 is a simplified flow diagram illustrating security aspects of FLOOD packet processing in accordance with an embodiment of the present invention; and
[0033] FIG. 6 is a simplified flow diagram illustrating security aspects of RESPONSE packet processing in accordance with an embodiment of the present invention.
[0034] While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
[0035] Turning to the drawings, wherein like reference numerals refer to like elements, the invention is illustrated as being implemented in a suitable computing environment. Although not required, the invention will be described in the general context of computer-executable instructions, such as program modules, being executed by a personal computer. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Moreover, those skilled in the art will appreciate that the invention may be practiced with other computer system configurations, including hand-held devices, multi-processor systems, microprocessor based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, and the like. The invention may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices.
[0036] FIG. 1 illustrates an example of a suitable computing system environment 100 on which the invention may be implemented. The computing system environment 100 is only one example of a suitable computing environment and is not intended to suggest any limitation as to the scope of use or functionality of the invention. Neither should the computing environment 100 be interpreted as having any dependency or requirement relating to any one or combination of components illustrated in the exemplary operating environment 100 .
[0037] The invention is operational with numerous other general purpose or special purpose computing system environments or configurations. Examples of well known computing systems, environments, and/or configurations that may be suitable for use with the invention include, but are not limited to, personal computers, server computers, hand-held or laptop devices, multiprocessor systems, microprocessor-based systems, set top boxes, programmable consumer electronics, network PCs, minicomputers, mainframe computers, distributed computing environments that include any of the above systems or devices, and the like.
[0038] The invention may be described in the general context of computer-executable instructions, such as program modules, being executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The invention may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote computer storage media including memory storage devices.
[0039] With reference to FIG. 1 , an exemplary system for implementing the invention includes a general purpose computing device in the form of a computer 110 . Components of computer 110 may include, but are not limited to, a processing unit 120 , a system memory 130 , and a system bus 121 that couples various system components including the system memory to the processing unit 120 . The system bus 121 may be any of several types of bus structures including a memory bus or memory controller, a peripheral bus, and a local bus using any of a variety of bus architectures. By way of example, and not limitation, such architectures include Industry Standard Architecture (ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, Video Electronics Standards Associate (VESA) local bus, and Peripheral Component Interconnect (PCI) bus also known as Mezzanine bus.
[0040] Computer 110 typically includes a variety of computer readable media. Computer readable media can be any available media that can be accessed by computer 110 and includes both volatile and nonvolatile media, removable and non-removable media. By way of example, and not limitation, computer readable media may comprise computer storage media and communication media. Computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by computer 110 . Communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media. The term “modulated data signal” means a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, RF, infrared and other wireless media. Combinations of the any of the above should also be included within the scope of computer readable media.
[0041] The system memory 130 includes computer storage media in the form of volatile and/or nonvolatile memory such as read only memory (ROM) 131 and random access memory (RAM) 132 . A basic input/output system 133 (BIOS), containing the basic routines that help to transfer information between elements within computer 110 , such as during start-up, is typically stored in ROM 131 . RAM 132 typically contains data and/or program modules that are immediately accessible to and/or presently being operated on by processing unit 120 . By way of example, and not limitation, FIG. 1 illustrates operating system 134 , application programs 135 , other program modules 136 , and program data 137 .
[0042] The computer 110 may also include other removable/non-removable, volatile/nonvolatile computer storage media. By way of example only, FIG. 1 illustrates a hard disk drive 141 that reads from or writes to non-removable, nonvolatile magnetic media, a magnetic disk drive 151 that reads from or writes to a removable, nonvolatile magnetic disk 152 , and an optical disk drive 155 that reads from or writes to a removable, nonvolatile optical disk 156 such as a CD ROM or other optical media. Other removable/non-removable, volatile/nonvolatile computer storage media that can be used in the exemplary operating environment include, but are not limited to, magnetic tape cassettes, flash memory cards, digital versatile disks, digital video tape, solid state RAM, solid state ROM, and the like. The hard disk drive 141 is typically connected to the system bus 121 through a non-removable memory interface such as interface 140 , and magnetic disk drive 151 and optical disk drive 155 are typically connected to the system bus 121 by a removable memory interface, such as interface 150 .
[0043] The drives and their associated computer storage media discussed above and illustrated in FIG. 1 , provide storage of computer readable instructions, data structures, program modules and other data for the computer 110 . In FIG. 1 , for example, hard disk drive 141 is illustrated as storing operating system 144 , application programs 145 , other program modules 146 , and program data 147 . Note that these components can either be the same as or different from operating system 134 , application programs 135 , other program modules 136 , and program data 137 . Operating system 144 , application programs 145 , other program modules 146 , and program data 147 are given different numbers hereto illustrate that, at a minimum, they are different copies. A user may enter commands and information into the computer 110 through input devices such as a keyboard 162 and pointing device 161 , commonly referred to as a mouse, trackball or touch pad. Other input devices (not shown) may include a microphone, joystick, game pad, satellite dish, scanner, or the like. These and other input devices are often connected to the processing unit 120 through a user input interface 160 that is coupled to the system bus, but may be connected by other interface and bus structures, such as a parallel port, game port or a universal serial bus (USB). A monitor 191 or other type of display device is also connected to the system bus 121 via an interface, such as a video interface 190 . In addition to the monitor, computers may also include other peripheral output devices such as speakers 197 and printer 196 , which may be connected through a output peripheral interface 195 .
[0044] The computer 110 may operate in a networked environment using logical connections to one or more remote computers, such as a remote computer 180 . The remote computer 180 may be another personal computer, a server, a router, a network PC, a peer device or other common network node, and typically includes many or all of the elements described above relative to the personal computer 110 , although only a memory storage device 181 has been illustrated in FIG. 1 . The logical connections depicted in FIG. 1 include a local area network (LAN) 171 and a wide area network (WAN) 173 , but may also include other networks. Such networking environments are commonplace in offices, enterprise-wide computer networks, intranets and the Internet.
[0045] When used in a LAN networking environment, the personal computer 110 is connected to the LAN 171 through a network interface or adapter 170 . When used in a WAN networking environment, the computer 110 typically includes a modem 172 or other means for establishing communications over the WAN 173 , such as the Internet. The modem 172 , which may be internal or external, may be connected to the system bus 121 via the user input interface 160 , or other appropriate mechanism. In a networked environment, program modules depicted relative to the personal computer 110 , or portions thereof, may be stored in the remote memory storage device. By way of example, and not limitation, FIG. 1 illustrates remote application programs 185 as residing on memory device 181 . It will be appreciated that the network connections shown are exemplary and other means of establishing a communications link between the computers may be used.
[0046] In the description that follows, the invention will be described with reference to acts and symbolic representations of operations that are performed by one or more computer, unless indicated otherwise. As such, it will be understood that such acts and operations, which are at times referred to as being computer-executed, include the manipulation by the processing unit of the computer of electrical signals representing data in a structured form. This manipulation transforms the data or maintains it at locations in the memory system of the computer, which reconfigures or otherwise alters the operation of the computer in a manner well understood by those skilled in the art. The data structures where data is maintained are physical locations of the memory that have particular properties defined by the format of the data. However, while the invention is being described in the foregoing context, it is not meant to be limiting as those of skill in the art will appreciate that various of the acts and operation described hereinafter may also be implemented in hardware.
[0047] As introduced above, the success of a peer-to-peer (P2P) protocol depends on the protocol's ability to establish valid connections between selected entities. Because a particular user may connect to the network in various ways at various locations having different addresses, a preferred approach is to assign a unique identity to the user, and then resolve that identity to a particular address through the protocol. Such a peer-to-peer name resolution protocol (PNRP) to which the security infrastructure of the instant invention finds particular applicability is described in co-pending application Ser. No. 09/942,164, entitled Peer-To-Peer Name Resolution Protocol (PNRP) And Multilevel Cache For Use Therewith, filed on Aug. 29, 2001, the teachings and disclosure of which are hereby incorporated in their entireties by reference thereto. However, one skilled in the art will recognize from the following teachings that the security infrastructure and methods of the present invention are not limited to the particular peer-to-peer protocol of this co-pending application, but may be applied to other protocols with equal force.
[0048] As discussed in the above-incorporated co-pending application, the peer name resolution protocol (PNRP) is a peer-based name-to-address resolution protocol. Names are 256-bit numbers called PNRP IDs. Addresses consist of an IPv4 or IPv6 address, a port, and a protocol number. When a PNRP ID is resolved into an address, a peer address certificate (PAC) is returned. This certificate includes the target's PNRP ID, current IP address, public key, and many other fields. An instance of the PNRP protocol is called a node. A node may have one or more PNRP IDs registered locally. A node makes an ID-to-address mapping discoverable in PNRP via registration. Each registration includes a locally constructed peer certificate, and requires an appropriate view of the PNRP cache. Hosts which are not PNRP nodes may resolve PNRP IDs into IP addresses via a PNRP DNS gateway. A PNRP DNS gateway accepts DNS ‘A’ and ‘AAAA’ queries, performs a PNRP search for a subset of the hostname specified, and returns the results as a DNS query answer.
[0049] As indicated above, PNRP provides a peer-based mechanism associating P2P and PNRP IDs with peer address certificates (PACs). A P2P ID is a persistent 128-bit identifier. P2P IDs are created by hashing a correctly formatted P2P name. There are two types of P2P IDs, secure and insecure. A secure P2P ID is an ID with a verifiable relationship to a public key. An insecure P2P ID is any ID which is not secure. A given P2P ID may be published by many different nodes. PNRP uses a ‘service location’ suffix to ensure each published instance has a unique PNRP ID. A ‘service location’ is a 128-bit number corresponding to a unique network service endpoint. Service locations have some recognizable elements, but should be considered opaque by PNRP clients. A service location has two important properties. At any moment, only one socket in the cloud corresponds to a given service location. When two service locations are compared, the length of the common prefix for each is a reasonable measure of network proximity. Two service locations which start with the same four bits are no further apart than two which start with the same three bits.
[0050] A P2P ID is uniquely identified by its catenation with the service location. The resulting 256-bit (32 byte) identifier is called a PNRP ID. PNRP nodes register a PNRP ID by invoking PNRP services with a P2P name, authority, and several other parameters. PNRP services then creates and maintains a Peer Address Certificate (PAC) containing the submitted data. PACs include at a minimum a PNRP ID, certificate validity interval, service and PNRP address, public key, and a cryptographic signature generated over select PAC contents.
[0051] Creation and registration of PNRP IDs is only one part of the PNRP service. The PNRP service execution can be divided into four phases. The first is PNRP cloud discovery. During this phase a new node must find an existing node in the cloud it wishes to join. The cloud may be the global PNRP cloud, a site local (enterprise) cloud, or a link local cloud. Once found, the second phase of joining a PNRP cloud is entered. Once the new node has found an existing node, it performs a SYNCHRONIZE procedure to obtain a copy of the existing node's top cache level. A single cache level provides enough basis for a new node to start participating in the cloud. Once the SYNCHRONIZATION has been achieved, the next phase, active participation in the cloud, may be begun. After initialization has completed, the node may participate in PNRP ID registration and resolution. During this phase, the peer also performs regular cache maintenance. When the node is done, it enters the fourth phase, leaving the cloud. The node un-registers any locally registered PNRP IDs, then terminates.
[0052] The PNRP protocol consists of nine different types of packets, some of which have been introduced above. It should be noted, however, that in this application the names of the packets are used merely to facilitate an understanding of their functionality, and should not be taken as limiting the form or format of the packet or message itself The RESOLVE packet requests resolution of a target PNRP ID into a PAC. A RESPONSE packet is the result of a completed RESOLVE request. The FLOOD packet contains a PAC intended for the PNRP cache of the recipient. A SOLICIT packet is used to ask a PNRP node to ADVERTISE its top level cache. The requested ADVERTISE packet contains a list of PNRP IDs for PACs in a node's top level cache. A REQUEST packet is used to ask a node to flood a subset of ADVERTISE'd PACs. An INQUIRE packet is used to insecurely ask a node whether a specific PNRP ID is registered at that node. To confirm local registration of a PNRP ID, an AUTHORITY packet is used. This packet optionally provides a certification chain to help validate the PAC for that ID. An ACK packet acknowledges receipt and/or successful processing of certain messages. Finally, the REPAIR packet is used to try to merge clouds that may be split.
[0053] Once a node is fully initialized, it may participate in the PNRP cloud by performing five types of activities. First, a node may register and un-register PNRP IDs. When a PNRP ID is registered, the PNRP service creates a peer address certificate (PAC) associating the PNRP ID, service address port and protocol, PNRP address port and protocol, and a public key. This PAC is entered into the local cache, and a RESOLVE is initiated using the new PAC as the source, and [PNRP ID+1] as the target. This RESOLVE is processed by a number of nodes with PNRP IDs very similar to the registered ID. Each recipient of the RESOLVE adds the new node's PAC to their cache, thereby advertising the new PNRP ID in the cloud. When a PNRP ID is un-registered, an updated PAC is created with a ‘revoke’ flag set. The updated PAC is flooded to all entries in the lowest level of the local cache. Each recipient of the FLOOD checks its cache for an older version of the PAC. If one is found, the recipient removes the PAC from its cache. If the PAC is removed from the lowest cache level, the recipient in turn FLOODs the revocation to the PNRP nodes represented by all other PACs in its lowest cache level.
[0054] The PNRP node may also participate in PNRP ID resolution. As discussed in the above incorporated application, PNRP IDs are resolved into PACs by routing RESOLVE messages successively closer to the target PNRP ID. When a node receives a RESOLVE, it may reject the RESOLVE back to the previous hop, respond to the previous hop with a RESPONSE, or forward the RESOLVE to a node whose PNRP ID is closer to the target ID than the node's own. The node also receives and forwards RESPONSE packets as part of resolution. The PNRP node may also initiate RESOLVEs on behalf of a local client. The PNRP service provides an API to allow asynchronous resolution requests. The local node originates RESOLVE packets, and eventually receives a corresponding RESPONSE.
[0055] The PNRP node also honors cache synchronization requests. Upon receiving a SOLICIT packet, the node responds with an ADVERTISE packet, listing the PNRP IDs in its highest cache level. The solicitor node then sends a REQUEST listing the PNRP IDs for any ADVERTISE'd PACs it wants. Each REQUESTed cache entry is then FLOODed to the REQUESTor. Finally, and as will be discussed more fully below, the PNRP also performs identity validation. Identity validation is a threat mitigation device used to validate PACs. Identity validation basically has two purposes. First, identity validation ensures that the PNRP node specified in a PAC has the PNRP ID from that PAC locally registered. Second, for secure PNRP IDs (discussed below), identity validation ensures that the PAC was signed using a key with a cryptographically provable relationship to the authority in the PNRP ID.
[0056] Having now provided a working knowledge of the PNRP system for which an embodiment of the security infrastructure of the present invention finds particular relevance, attention is now turned to the security mechanisms provided by the security infrastructure of the present invention. These mechanisms are provided by the system of the present invention to eliminate, or at a minimum mitigate, the effect of the various attacks that may be posed by a malicious node in a P2P cloud as discussed above. The PNRP protocol does not have any mechanism to prevent these attacks, nor is there a single solution to address all of these threats. The security infrastructure of the present invention, however, minimizes the disruption that may be caused by a malicious node, and may be incorporated into the PNRP protocol.
[0057] As with many successful P2P protocols, entities can be published for easy discovery. To provide security and integrity to the P2P protocol, however, each identity preferably includes an attached identity certificate. However, a robust security architecture will be able to handle both secure and insecure entities. In accordance with an embodiment of the present invention, this robustness is provided through the use of self-verifying PACs.
[0058] A secure PAC is made self-verifying by providing a mapping between the ID and a public key. This will prevent anyone from publishing a secure PAC without having the private key to sign that PAC, and thus will prevent a large number of identity theft attacks. The keeper of the ID private key uses the certificate to attach additional information to the ID, such as the IP address, friendly name, etc. Preferably, each node generates its own pair of private-public keys, although such may be provided by a trusted supplier. The public key is then included as part of the node identifier. Only the node that created the pair of keys has the private key with which it can prove that it is the creator of the node identity. In this way, identity theft may be discovered, and is, therefore, deterred.
[0059] A generic format for such certificates may be represented as [Version, ID, <ID Related Info>, Validity, Algorithms, P.sub.Issuer]K.sub.Issuer. Indeed, P2P name/URL is part of the basic certificate format, regardless of whether it is a secure or insecure ID. As used in this certificate representation, Version is the certificate version, ID is the identifier to be published, <ID Related Info> represents information to be associated with the ID, Validity represents the period of validity expressed in a pair of From-To dates expressed as Universal Date Time (aka GMT), Algorithms refers to the algorithms used for generating the key pairs, and for signing, and P.sub.Issuer is the public key of the certificate issuer. If the certificate issuer is the same as the ID owner then this is P.sub.ID the public key of the ID owner. The term K.sub.Issuer is the private key corresponding to P.sub.Issuer. If the certificate issuer is the ID owner then this is K.sub.ID, the private key of the ID owner.
[0060] In a preferred embodiment, the <ID related info> comprises the address tuple where this ID can be found, and the address tuple for the PNRP service of the issuer. In this embodiment, the address certificate becomes [Version, ID, <Address>.sub.ID, <Address>.sub.PNRP, Validity, Revoke Flag, Algorithms, P.sub.Issuer]K.sub.Issuer. In this expanded representation, the ID is the identifier to be published, which can be a Group ID or Peer ID. The <Address> is the tuple of IPv6 address, port, and protocol. <Address>.sub.ID is the address tuple to be associated with the ID. <Address>.sub.PNRP is the address tuple of the PNRP service (or other P2P service) on the issuer machine. This is preferably the address of the PNRP address of the issuer and will be used by the other PNRP nodes to verify the validity of the certificate. Validity is the period of validity expressed in a pair of From-To dates. The Revoke Flag, when set, marks a revocation certificate. The P.sub.Issuer is the public key of the certificate issuer, and the K.sub.Issuer is the private key corresponding to P.sub.Issuer. If the certificate issuer is the ID owner then this is K.sub.ID, the private key of the ID.
[0061] In a preferred embodiment of the present invention, the following conditions have to be met for a certificate to be valid. The certificate signature must valid, and the certificate cannot be expired. That is, the current date expressed as UDT must be in the range specified by the Validity field. The hash of the public key must also match the ID. If the Issuer is the same as the ID owner then the hashing of the issuer's public key into the ID has to verify. If the P.sub.Issuer is different from P.sub.ID then there must be a chain of certificates leading to a certificate signed with K.sub.ID. Such a chain verifies the relationship between the issuer and the ID owner. Additionally, in the case when a certification revocation list (CRL) is published for that class of IDs and the CRL is accessible, then the authenticator can verify that none of the certificates in the chain appear in the CRL.
[0062] The security infrastructure of the present invention also handles insecure PACs. In accordance with the present invention, an insecure PAC is made self-verifying by including the uniform resource identifier (URI) from which the ID is derived. Indeed, both secure and insecure IDs include the URI in the PAC. The URI is of the format “p2p://URI”. This will prevent a malicious node from publishing another node's secure ID in an insecure PAC.
[0063] The security infrastructure of the present invention also allows for the use of insecure IDs. The problem with insecure IDs is that they are very easy to forge: a malicious node can publish an insecure ID of any other node. Insecure IDs also open security holes wherein it becomes possible to make discovery of a good node difficult. However, by including a URI in accordance with the present invention, the insecure IDs cannot affect the secure IDs in any way. Further, the infrastructure of the present invention requires that the PACs containing insecure IDs be in the same format as secure PACs, i.e. they contain public key and private keys. By enforcing the same structure on both insecure PACs and secure PACs, the bar for generating PACs is not lowered. Further, by including a URI in the PAC it is not computationally feasible to generate a URI that maps to a specific secure ID.
[0064] One issue that arises is the timing of PAC verification, recognizing a trade off between increased P2P cloud security and increased overhead. The PAC contained in the various packets discussed above has to be verified at some point, however. This PAC verification includes checking the ID signature validity and checking if the ID corresponds to the public key for secure IDs. To balance the overhead versus security issues, one embodiment of the present invention verifies the PACs before any processing of that packet is done. This ensures that invalid data is never processed. However, recognizing that PAC verification may slow down the packet processing, which might not be suitable for certain classes of packets (e.g. RESOLVE packets), an alternate embodiment of the present invention does not verify the PAC in these packets.
[0065] In addition to PAC verification, the security infrastructure of the present invention also performs an ID ownership check to validate the PAC. As discussed above, identity theft can be discovered by simple validation of the address certificate before using that address in PNRP or other P2P protocols. This validation may entail simply verifying that the ID is the hash of the public key included in the certificate. The ownership validation may also entail the issuance of an INQUIRE packet to the address in that PAC. The INQUIRE packet will contain the ID to be verified, and a transaction ID. If the ID is present at that address, the node should acknowledge that INQUIRE. If the ID is not present at that address, the node should not acknowledge that INQUIRE. If the certificate chain is required to verify the identity, the node returns the complete certificate chain. While signature and ID->URL validation is still complex and a significant use of resources, as is validating the chain of trust in a supplied cert chain, the system of the present invention avoids any sort of challenge/response protocol, which would add an additional level of complexity to PAC validation. Further, the inclusion of the transaction ID prevents the malicious node from pre-generating the response to the INQUIREs. Additionally, this mechanism dispenses with the requirement that the PAC carry the complete certificate chain.
[0066] The ID ownership check is also facilitated in the system of the present invention by modifying the standard RESOLVE packet so that it can also perform the ID ownership check. This modified RESOLVE packet contains the ID of the address to which the RESOLVE is being forwarded. If the ID is at that address, it will send an ACK, otherwise it will send a NACK. If the ID does not process the RESOLVE or if a NACK is received, the ID is removed from the cache. In this way a PAC is validated without resorting to any sort of challenge/response protocol and without sending any special INQUIRE packet by, in essence, piggybacking an INQUIRE message with the RESOLVE. This piggybacking process will be discussed again below with respect to FIG. 2 . This procedure makes it easy to flush out invalid or stale PACs.
[0067] This identity validation check happens at two different times. The first is when a node adds a PAC to one of its lowest two cache levels. PAC validity in the lowest two cache levels is critical to PNRP's ability to resolve PNRP IDs. Performing identity validation before adding a PAC to either of these two levels mitigates several attacks. ID ownership is not performed if the PAC is added to any higher level cache because of the turnover in these higher levels. It has been determined that nearly 85% of all PAC entries in the higher levels of cache are replaced or expire before they are ever used. As such, the probability of seeing any effect from having an invalid PAC in these higher levels is low enough not to justify performing the ID validation when they are entered.
[0068] When it is determined that an entry would belong in one of the two lowest cache levels, the PAC is placed in a set aside list until its identity can be validated. This first type of identity validation uses the INQUIRE message. Such an identity validation confirms a PAC is still valid (registered) at its originating node, and requests information to help validate authority of the originating node to publish that PAC. One flag in the INQUIRE message is defined for the ‘flags’ field, i.e. RF_SEND_CHAIN, that requests the receiver to send a certificate chain (if any exists) in an AUTHORITY response. If the receiver of the INQUIRE does not have authority to publish the PAC or if the PAC is no longer locally registered, the receiver simply drops the INQUIRE message. Since the local node does not receive a proper response via an AUTHROITY message, the bad PAC will never be entered into its cache, and therefore can have no malicious effect on its operation in the P2P cloud.
[0069] If the receiver of the INQUIRE does have the authority to issue the PAC and if it is still locally registered, that node will respond 200 to the INQUIRE message with an AUTHORITY message as illustrated in FIG. 2 . While not illustrated in FIG. 2 , the receiving node in an embodiment of the present invention checks to see if the AUTHORITY message says that the ID is still registered at the node which sent the AUTHORITY. Once the local node determines 202 that this AUTHORITY message is in response to the INQUIRE message, it removes the PAC from the set aside list 204 . If the certificate chain was requested 206 , the AUTHORITY message is checked to see if the certificate chain is present and valid 208 . If the certificate chain is present and valid, then the PAC is added to the cache and marked as valid 210 . Otherwise, the PAC is deleted 212 . If the certificate chain was not requested 206 , then the PAC is simply added to the cache and marked as valid 210 .
[0070] As may now be apparent, this AUTHORITY message is used to confirm or deny that a PNRP ID is still registered at the local node, and optionally provides a certificate chain to allow the AUTHORITY recipient to validate the node's right to publish the PAC corresponding to the target ID. In addition to the INQUIRE message, the AUTHORITY message may be a proper response to a RESOLVE message as will be discussed below. The AUTHORITY message includes various flags that may be set by the receiving node to indicate a negative response. One such flag is the AF_REJECT_TOO_BUSY flag, which is only valid in response to a RESOLVE. This flag indicates that the host is too busy to accept a RESOLVE, and tells the sender that it should forward the RESOLVE elsewhere for processing. While not aiding in the identity validation, it is another security mechanism of the present invention to prevent a DoS attack as will be discussed more fully below. The flag AF_INVALID_SOURCE, which is only valid in response to a RESOLVE, indicates that the Source PAC in the RESOLVE is invalid. The AF_INVALID_BEST_MATCH flag, which is also only valid in response to a RESOLVE, indicates that the ‘best match’ PAC in the RESOLVE is invalid. The AF_UNKNOWN_ID flag indicates that the specified ‘validate’ PNRP ID is not registered at this host. Other flags in the AUTHORITY message indicate to the receiving node that requested information is included. The AF_CERT_CHAIN flag indicates that a certificate chain is included that will enable validation of the relationship between the ‘validate’ PNRP ID and the public key used to sign the PAC. The AUTHORITY message is only sent as an acknowledgement/response to either the INQUIRE or RESOLVE messages. If an AUTHORITY is ever received out of this context, it is discarded.
[0071] The second time that identity validation is performed is opportunistically during the RESOLVE process. As discussed, PNRP caches have a high rate of turnover. Consequently, most cache entries are overwritten in the cache before they are ever used. Therefore, the security infrastructure of the present invention does not validate these PACs until and unless they are actually used. When a PAC is used to route a RESOLVE path, the system of the present invention piggybacks identity validation on top of the RESOLVE packet as introduced above. The RESOLVE contains a ‘next hop’ ID which is treated the same as the ‘target ID’ in an INQUIRE packet. This RESOLVE is then acknowledged with an AUTHORITY packet, the same as is expected for an INQUIRE discussed above. If an opportunistic identity validation fails, the receiver of the RESOLVE is not who the sender believes they are. Consequently, the RESOLVE is routed elsewhere and the invalid PAC is removed from the cache.
[0072] This process is also illustrated in FIG. 2 . When a PNRP node P receives an AUTHORITY packet 200 with the header Message Type field set to RESOLVE 202 , the receiving node examines the AUTHORITY flags to determine if this AUTHORITY flag is negative 214 , as discussed above. If any of the negative response flags are set in the AUTHORITY message, the PAC is deleted 216 from the cache and the RESOLVE is routed elsewhere. The address to which the RESOLVE was sent is appended to the RESOLVE path and marked REJECTED. The RESOLVE is then forwarded to a new destination. If the AUTHORITY is not negative and if the certificate chain was requested 218 , the AUTHORITY message flag AF_CERT_CHAIN is checked to see if the certificate chain is present. If it is present the receiving node should perform a chain validation operation on the cached PAC for the PNRP ID specified in validate. The chain should be checked to ensure all certificates in it are valid, and the relationship between the root and leaf of the chain is valid. The hash of the public key for the chain root should, at a minimum, be compared to the authority in the PACs P2P name to ensure they match. The public key for the chain leaf should be compared against the key used to sign the PAC to ensure they match. If any of these checks fail or if the certificate chain is not present when requested 220 , the PAC should be removed from the cache 222 and the RESOLVE reprocessed. If the requested certificate chain is included and is validated 220 , the PAC corresponding to the validate PNRP ID should be marked as fully validated 224 . If desired, the PNRP ID, PNRP service address, and validation times may be retained from the PAC and the PAC itself deleted from the cache to save memory.
[0073] As an example of this identity validation, assume that ‘P’ is a node requesting an identity validation for PNRP ID ‘T’. ‘N’ is the node receiving the identity validation request. This could happen as a result of P receiving either an INQUIRE packet with target ID=T, or a RESOLVE packet with next hop=T. N checks its list of PNRP IDs registered locally. If T is not in that list, then the received packet type is checked. If it was an INQUIRE, N silently drops the INQUIRE request. After normal retransmission attempts expire, P will discard the PAC as invalid and processing is done. If it was a RESOLVE, N responds with an AUTHORITY packet indicating ID T is not locally registered. P then sends the RESOLVE elsewhere. If T is in the list of PNRP IDs at N, N constructs an AUTHORITY packet and sets the target ID to T. If T is an insecure ID, then N sends the AUTHORITY packet to P. If T is a secure ID, and the authority for the secure ID is the key used to sign the PAC, then N sends the AUTHORITY packet to P. If neither of these are true and if the RF_SEND_CHAIN flag is set, then N retrieves the certificate chain relating the key used to sign the PAC to the authority for PNRP ID T. The certificate chain is inserted into the AUTHORITY packet, and then N sends the AUTHORITY packet to P. At this point, if T is an insecure ID processing is completed. Otherwise, P validates the relationship between the PAC signing key and the authority used to generate the PNRP ID T. If the validation fails, the PAC is discarded. If validation fails and the initiating message was a RESOLVE, P forwards the RESOLVE elsewhere.
[0074] As may now be apparent from these two times that identity ownership verification is performed, through either the INQUIRE or the modified RESOLVE packet, an invalid PAC cannot be populated throughout the P2P cloud using a FLOOD, and searches will not be forwarded to non-existent or invalid IDs. The PAC validation is necessary for FLOOD because, if the FLOOD packet is allowed to propagate in the network without any validation, then a DoS attack may result. Through these mechanisms, a popular node will not be flooded with ID ownership check because its ID will belong to only a very few nodes' lowest two cache levels.
[0075] As described more fully in the above referenced co-pending application, a PNRP node N learns about a new ID in one of four ways. It may learn of a new ID through the initial flooding of a neighbor's cache. Specifically, when a P2P node comes up it contacts another node member of the P2P cloud and initiates a cache synchronization sequence. It may also learn of a new ID as a result of a neighbor flooding a new record of its lowest cache. For example, assume that node N appears as an entry in the lowest level cache of node M. When M learns about a new ID, if the ID fits in its lowest level cache, it will flood it to the other entries in that cache level, respectively to N. A node may also learn of a new ID as a result of a search request. The originator of a search request inserts its address certificate in the request, and the PAC for the ‘best match’ to the search request so far also inserts its PAC into the request. In this way, all of the nodes along the search request path will update their cache with the search originator's address, and the best match's address. Similarly, a node may learn of a new ID as a result of a search response. The result of a search request travels a subset of the request path in reverse order. The nodes along this path update their cache with the search result.
[0076] According to PNRP, when the node first comes up it discovers a neighbor. As discussed above, however, if the node that is first discovered is a malicious node, the new node can be controlled by the malicious node. To prevent or minimize the possibility of such occurrence, the security infrastructure of the present invention provides two mechanisms to ensure secure node boot up. The first is randomized discovery. When a node tries to discover another node that will allow it to join the PNRP cloud, the last choice for discovery is using multicast/broadcast because it is the most insecure discovery method of PNRP. Due to the nature of discovery it is very difficult to distinguish between a good and bad node. Therefore, when this multicast/broadcast method is required, the security infrastructure of the present invention causes the node to randomly select one of the nodes who responded to the broadcast discovery message (MARCOPOLO or an existing multicast discovery protocol e.g., SSDP). By selecting a random node, the system of the present invention minimizes the probability of selecting a malicious node. The system of the present invention also performs this discovery without using any of its IDs. By not using IDs during discovery, the system of the present invention prevents the malicious node from targeting a specific ID.
[0077] A second secure node boot up mechanism is provided by a modified sync phase during which the node will maintain a bit vector. This modified synch phase mechanism may best be understood through an example illustrated in the simplified flow diagram of FIG. 3 . Assume that Alice 226 sends a SOLICIT 228 to Bob 230 with her PAC in it. If Alice's PAC is not valid 232 , Bob 230 simply drops the SOLICIT 234 . If the PAC is valid, Bob 230 will then maintain a bit vector for storing the state of this connection. When this SOLICIT is received, Bob 230 generates 236 a nonce and hashes it with Alice's PNRP ID. The resulting number will be used as an index in this bit vector that Bob will set. Bob 230 then responds 238 to Alice 226 with an ADVERTISE message. This ADVERTISE will contain Bob's PAC and a nonce encrypted with Alice's public key, apart from other information, and will be signed by Bob 230 . When Alice 226 receives this ADVERTISE, she verifies 240 the signature and Bob's PAC. If it cannot be verified, it is dropped 241 . If it can be verified, Alice 226 then decrypts 242 the nonce. Alice 226 will then generate 244 a REQUEST that will contain this nonce and Alice's PNRP ID. Bob 230 will process 246 this REQUEST by hashing Alice's PNRP ID with the nonce sent in the REQUEST packet. If 248 the bit is set in the bit vector having the hashed results as an index, then Bob will clear the bits and start processing the REQUEST 250 . Otherwise, Bob will ignore the REQUEST 252 as it may be a replay attack.
[0078] This makes the node boot up a secure process because the sequence cannot be replayed. It requires minimal overhead in terms of resources consumed, including CPU, network ports, and network traffic. No timers are required to be maintained for the state information, and only the ID that initiated the sync up will be sent data. Indeed, this modified sync phase is asynchronous, which allows a node to process multiple SOLICITs simultaneously.
[0079] Many of the threats discussed above can be minimized by controlling the rate at which the packets are processed, i.e. limiting node resource consumption. The idea behind this is that a node should not consume 100% of its CPU trying to process the PNRP packets. Therefore, in accordance with an embodiment of the present invention a node may reject processing of certain messages when it senses that such processing will hinder its ability to function effectively.
[0080] One such message that the node may decide not to process is the RESOLVE message received from another node. This process is illustrated in simplified form in FIG. 4 . Once a RESOLVE message is received 254 , the node will check 256 to see if it is currently operating at a CPU capacity greater than a predetermined limit. If its CPU is too busy to process the RESOLVE message, it will send 258 an AUTHORITY message with the AF_REJECT_TOO_BUSY flag set indicating its failure to process the request because it is too busy. If the CPU is not too busy 256 , the node will determine 260 if all of the PACs in the RESOLVE message are valid, and will reject 262 the message if any are found to be invalid. If all of the PACs are valid 260 , the node will process 264 the RESOLVE.
[0081] If the node can respond 266 to the RESOLVE, the node will 268 convert the RESOLVE into a RESPONSE and send it to the node from which it received the RESOLVE. If, however, the target ID is not locally registered, the node will 270 calculate the bitpos as the hash of the fields in the RESOLVE and will set the corresponding bitpos in the bit vector. As discussed briefly above, this bit vector is used as a security mechanism to prevent the processing of erroneous reply messages when the node has not sent out any messages to which a reply is expected. The node finds the next hop to which to forward the RESOLVE, with the appropriate modifications to evidence its processing of the message. If 272 the node to which the RESOLVE is to be forwarded has already been verified, the node simply forwards 276 the RESOLVE to that next hop. If 272 this selected next hop has not yet been verified, the node piggybacks 274 an ID ownership request on the RESOLVE and forwards 276 it to that node. In response to the piggybacked ID ownership request, the node will expect to receive an AUTHORITY message as discussed above, the process for which is illustrated in FIG. 2 . As illustrated in FIG. 2 , if a validating AUTHORITY is not received at step 214 , the PAC of the node to which the RESOLVE was forwarded is deleted 216 from the cache and the RESOLVE is reprocessed from step 254 of FIG. 4 .
[0082] Another message that the node may decide not to process because its CPU is too busy is the FLOOD message. In this process, illustrated in simplified form in FIG. 5 , if 278 the new information present in the FLOOD goes to either of the lowest two cache levels, the PAC is checked to determine if it is valid 280 . If the PAC is not valid, the FLOOD is rejected 284 . However, if the PAC is valid 280 , it is put into a set-aside list 282 . The entries in the set-aside list are taken at random intervals and are processed when the CPU is not too busy. Since these entries are going to be entered in the lowest two levels of cache, both the ID verification and the ownership validation are performed as discussed above. If 278 the new information present in the FLOOD goes to the higher cache levels and the CPU is too busy to process them 286 , then they are discarded 288 . If the node has available CPU processing capacity 286 , the PAC is checked to determine if it is valid 290 . If it is, then the PAC is added to the cache 292 , otherwise the FLOOD is rejected 294 .
[0083] Node boot up (SYNCHRONIZE) is another process that consumes considerable resources at a node, including not only CPU processing capacity but also network bandwidth. However, the synchronization process is required to allow a new node to fully participate in the P2P cloud. As such, the node will respond to the request from another node for the boot up if it has enough available resources at the given time. That is, as with the two messages just discussed, the node may refuse to participate in the boot up if its CPU utilization is too high. However, since this process consumes so much capacity, a malicious node can still exploit this by launching a large number of such sequences. As such, an embodiment of the security infrastructure of the present invention limits the number of node synchronizations that may be performed by a given node to prevent this attack. This limitation may additionally be time limited so that a malicious node cannot disable a node from ever performing such a synchronization again in the future.
[0084] Also discussed above were many search based attacks that could be launched or caused by a malicious node. To eliminate or minimize the effect of such search based attacks, the system of the present invention provides two mechanisms. The first is randomization. That is, when a node is searching for an appropriate next hop to which to forward a search request (RESOLVE), it identifies a number of possible candidate nodes and then randomly selects one ID out of these candidate IDs to which to forward the RESOLVE. In one embodiment, three candidate nodes are identified for the random selection. The IDs may be selected based on a weighted probability as an alternative to total randomization. One such method of calculating a weighted probability that the ID belongs to a non-malicious node is based on the distance of the PNRP ID from the target ID. The probability is then determined as an inverse proportionality to the ID distance between that node and the target node. In any event, this randomization will decrease the probability of sending the RESOLVE request to a malicious node.
[0085] The second security mechanism that is effective against search based attacks utilizes the bit vector discussed above to maintain state information. That is, a node maintains information identifying all of the RESOLVE messages that it has processed for which a response has not yet been received. The fields that are used to maintain the state information are the target ID and the address list in the RESOLVE packet. This second field is used to ensure that the address list has not been modified by a malicious node in an attempt to disrupt the search. As discussed above with the other instances of bit vector use, the node generates a hash of these fields from the RESOLVE and sets the corresponding bitpos in the bit vector to maintain a history of the processing of that RESOLVE.
[0086] As illustrated in the simplified flow diagram of FIG. 6 , when a RESPONSE message is received 296 from another node, the fields in this RESPONSE message are hashed 298 to calculate the bitpos. The node then checks 300 the bit vector to see if the bitpos is set. If the bit is not set, meaning that this RESPONSE is not related to an earlier processed RESOLVE, then the packet is discarded 302 . If the bitpos is set, meaning that this RESPONSE is related to an earlier processed RESOLVE, the bitpos is reset 304 . By resetting the bitpos, the node will ignore further identical RESPONSE messages that may be sent as part of a playback attack from a malicious node. The node then checks to make sure that all of the PACs in the RESPONSE message are valid 306 before processing the RESPONSE and forwarding it to the next hop. If any of the PACs are invalid 306 , then the node will reject 310 the packet.
[0087] The RESOLVE process mentions converting a RESOLVE request into a RESPONSE. This RESPONSE handling just discussed involves ensuring the RESPONSE corresponds to a recently received RESOLVE, and forwarding the RESPONSE on to the next hop specified. As an example, assume that node P receives a RESPONSE packet S containing a target PNRP ID, a BestMatch PAC, and a path listing the address of all nodes which processed the original RESOLVE before this node, ending with this node's own PNRP address. Node P acknowledges receipt of the RESPONSE with an ACK. Node P checks the RESPONSE path for its own address. Its address must be the last entry in the address list for this packet to be valid. Node P also checks its received bit vector to ensure that the RESPONSE matches a recently seen RESOLVE. If the RESPONSE does not match a field in the received bit vector, or if P's address is not the last address in the path list, the RESPONSE is silently dropped, and processing stops. P validates the BestMatch PAC and adds it to its local cache. If the BestMatch is invalid, the RESPONSE is silently dropped, and processing stops. P removes its address from the end of the RESPONSE path. It continues removing entries from the end of the RESPONSE path until the endmost entry has a flag set indicating a node that ACCEPTED the corresponding RESOLVE request. If the path is now empty, the corresponding RESOLVE originated locally. PNRP does an identity validation check on the BestMatch. If the identity validation check succeeds, the BestMatch is passed up to the request manager, else a failure indication is passed up. If the path is empty, processing is complete. If the path is not empty, the node forwards the RESPONSE packet to the endmost entry in the path list.
[0088] A need for a PNRP address certificate revocation exists whenever the published address certificate becomes invalid prior to the certificate expiration date (Validity/To field). Examples of such events are when a node is gracefully disconnecting from the P2P network, or when a node is leaving a group, etc. The revocation mechanism of the present invention utilizes the publishing of a revocation certificate. A revocation certificate has the Revoke Flag set, and the From date of the Validity field set to the current time (or the time at which the certificate is to become revoked) and the To field set to the same value as the previously advertised certificates. All the certificates for which all the following conditions are met are considered to be revoked: the certificate is signed by the same issuer; the ID matches the ID in the revocation certificate; the Address fields match the ones in the revocation certificate; the To date of the Validation field is the same as the To date of the Validation filed in the revocation certificate; and the From date of the Validation field precedes the From date of the Validation filed in the revocation certificate. Since the revocation certificate is signed, it ensures that a malicious node cannot disconnect anyone from the cloud.
[0089] The foregoing description of various embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Numerous modifications or variations are possible in light of the above teachings. The embodiments discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.
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A security infrastructure and methods are presented that inhibit the ability of a malicious node from disrupting the normal operations of a peer-to-peer network. The methods of the invention allow both secure and insecure identities to be used by nodes by making them self-verifying. When necessary or opportunistic, ID ownership is validated by piggybacking the validation on existing messages. The probability of connecting initially to a malicious node is reduced by randomly selecting to which node to connect. Further, information from malicious nodes is identified and can be disregarded by maintaining information about prior communications that will require a future response. Denial of service attacks are inhibited by allowing the node to disregard requests when its resource utilization exceeds a predetermined limit. The ability for a malicious node to remove a valid node is reduced by requiring that revocation certificates be signed by the node to be removed.
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[0001] This application is a continuation of U.S. patent application Ser. No. 12/367,964 filed Sep. 2, 2009, which is a continuation of U.S. patent application Ser. No. 10/999,640 filed Nov. 26, 2004, now abandoned, which claims the benefit of U.S. Provisional Application Ser. No. 60/544,022, filed Feb. 12, 2004.
BACKGROUND OF THE INVENTION
[0002] This invention relates generally to thermal printing technology, and more specifically to a process of creating background colors in thermal material and the product created thereby, and in particular, to application of the process to produce thermal labels and thermal paper.
[0003] Thermal printing is a type of non-impact printing which uses controlled concentrations of heat to develop an image on or in material having a thermal ink deposited thereon. A heated print head is positioned adjacent the thermally coated material, or substrate, which is in most instances paper, in order to cause a desired image to develop on or in the material.
[0004] Typically, thermal inks, when dry, appear clear or invisible, but produce an image in a specific color when heated. Thermal inks are typically applied as a one-color selection, meaning images of only one color are produced as the heat source, or heated print head, is applied to the thermally coated material.
[0005] If a background color other than white is used in conjunction with a thermal image, the thermal ink is often either coated on top of a colored material, which may have been colored by printing, dying, etc., or mixed with the thermal color ink coating to provide a tinted color background.
[0006] Although products are available which produce two colors, such as a black image and a red image, these colors appear as one or the other. Each color is dependent on the heat source developing at a lower temperature vs. a higher temperature. A two color thermally sensitive record material system is disclosed in U.S. Pat. No. 4,151,748.
[0007] Turning now to printing techniques, flexographic printing is becoming a common type of printing process in view of letterpress printing. Flexographic printing uses a flexo plate, which is flexible and resilient. The flexographic ink is typically a liquid instead of a paste, and the inking system is straightforward, using a gravure cylinder known as an anilox roll. The anilox roll is inked, wiped clean and transferred onto a raised image area of the flexo plate. The ink remains wet long enough to transfer to the paper or other substrate. Because the flexo plate is resilient, typically made of rubber or photopolymer, it can be impressed against a wide variety of surfaces and can print generally without voids.
[0008] Another known printing technique is flood coating, or flooding, which is the printing of a sheet completely with an ink or varnish and involves a process whereby a sponge-like applicator applies a color onto the material.
[0009] Tinting paper would screen or add white to a solid color for results of lightening that specific color.
SUMMARY OF THE INVENTION
[0010] Generally, the present invention includes a dye resin ink application process using flexographic printing, flood coating, tinting, or other suitable technique or process to add a color layer on top of a thermal ink layer of a material. This additional color provides a background color, such that the thermal image appears, upon application of the heat source, as being imaged onto the background color.
[0011] The process of the present invention may find a variety of uses on various thermal materials, and finds particular use in connection with the manufacture of heat-sensitive direct thermal labels or the manufacture of thermal paper rolls, including cash register-type rolls, poster printer format rolls, and any size rolls therebetween.
[0012] The process of the present invention allows two or more colors to be provided in direct thermal printing applications, as opposed to traditional one-color imaging. The present invention offers a variety of different background color choices to be provided to thermal-inked material in relatively small print runs by print shops having conventional equipment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The foregoing, as well as other objects of the present invention, will be further apparent from the following detailed description of the preferred embodiment of the invention, when taken together with the accompanying specification and the drawings, in which:
[0014] FIG. 1 is a schematic representation of the process of the present invention; and
[0015] FIG. 2 is a schematic representation of the process of the present invention using a flexographic printing apparatus.
[0016] FIG. 3 is a cross-sectional view of a product produced by the process of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0017] The accompanying drawings and the description which follows set forth this invention in its preferred embodiment. However, it is contemplated that persons generally familiar with thermal paper and printing techniques will be able to apply the novel characteristics of the processes and structures illustrated and described herein in other contexts by modification of certain details. Accordingly, the drawings and description are not to be taken as restrictive on the scope of this invention, but are to be understood as broad and general teachings.
[0018] Referring now to the drawings in detail, wherein like reference characters represent like elements or features throughout the various views, the process of the present invention for creating background colors on thermal material is indicated generally in the figures by reference character 10 .
[0019] A shown in FIG. 1 , the process 10 of the present invention includes, in one preferred embodiment, a printing or coating application system, generally P, which is used to apply a dye resin layer 32 to a thermal ink layer 34 ( FIG. 3 ) of a thermal material 21 .
[0020] System P, in one preferred embodiment, is a flexographic press print station, generally 11 , shown in FIG. 2 , and includes an ink pan 12 for holding a dye resin ink. A fountain roll 14 picks up ink from ink pan 12 and transfers it to an anilox roll 16 , the ink being metered and/or cleaned by a doctor blade 17 . Anilox roll 16 transfers the ink to a plate cylinder 18 , which prints the ink onto a substrate, or stock, 20 , which contacts impression cylinder 22 .
[0021] A process such as flexographic printing or flood coating capable of printing the dye resin ink is used to print up to the entire width of the substrate 20 being printed or coated. The flexographic press can include one or more stations 11 , each station 11 including an anilox roll and the capability to apply a particular color to substrate 20 . Accordingly, the more stations 11 the flexographic press has, the more colors which can be applied at one time. The number of stations 11 used could thus depend on the particular colors or color combinations desired, thereby offering increased flexibility in production of the coated material 30 .
[0022] Because most thermal printers are software driven, ink can be applied to specific locations on substrate 20 , if desired, to identify or represent specific information on such locations for the end user. The software can be coded to print in those locations or areas on substrate 20 as needed.
[0023] Using flexographic printing, the dye resin ink is printed on top of a thermal material 21 which has already been thermal-coated. This process provides a variety of background color options, limited only by the colors of inks available. Through use of several anilox rolls 16 and ink stations 11 , various ink colors can be applied at one time, thereby offering many color options. For instance, if an end user required paper with a black image appearing on a yellow background, such end user could potentially have such paper produced using a standard flexographic process by a printer for the quantity needed. The printer would purchase existing thermal coated material, or stock, 21 and print the background color on top of that stock 21 . Additionally, if the end user required a specific label printed with a number of separate colors, so that a desired image would appear in one or more of the colored areas, the printer could typically provide that also.
[0024] Because thermal products are typically produced in large quantities due to economies of scale, producing small quantities of products with special or unique colors can be cost prohibitive. The process of the present invention allows a conventional flexographic printer to purchase as little or as much stock from a supplier as needed and print such stock based on a particular customer's requirements.
[0025] The inks used in one preferred embodiment are made from dye resin particles, which are more transparent than pigmented inks. Dye particles have smaller molecules than pigmented inks. Pigmented inks are generally more dense and have greater staying power, especially in sunlight. Dye particles ordinarily easily oxidize and fade in sunlight. Resins help coat the particles and help the ink to dry. When mixed with a resin, the dye particles adhere together at a greater strength, are more resistant to fading and oxidation, and remain translucent enough to allow the thermal imaging to come through. Because pigmented inks are much more dense, printing with such inks, even at a nominal strength, inhibits the thermal image from coming through.
[0026] The present invention includes, in one preferred embodiment, use of conventional thermal stock, which could be labels, cash register-type paper, or poster printer paper (such as the type used with Varitronics®-brand or Fujifilm® brand poster printer models).
[0027] In accordance with the present invention, ink produced with dye resin particles is used to apply a top coating or layer 32 to a conventional thermal material 21 , having a thermal ink layer 34 , which may be on top of a base layer 36 , which is in turn on top of a substrate, or stock, 20 , such as, but not limited to, paper, such as label paper stock, poster printer paper stock, cash register-typer paper stock, etc. Dye resin ink is preferably used because of its translucent nature, as compared to typical pigmented inks, which are much more dense. Dye resin inks are available in a variety of colors, including bright fluorescent colors.
[0028] Although other thermal materials could be used in conjunction with practicing the process 10 of the present invention, process 10 can be used on suitable thermal papers of the type manufactured by Appleton Papers, referenced as Alpha 800 2.4 or Alpha 900 3.4. However, it is to be understood that the present invention is not limited to such thermal papers, and that process 10 could be used on other thermal materials, and such term, “thermal material,” as used herein, includes papers and substrates other than paper, such as plastics, films, fabrics, metals, polymers, foils, and other suitable materials.
[0029] As noted above, pigmented inks are generally more dense than dyes, since dye particles have smaller molecules than pigmented inks. Ordinarily, typical pigmented inks would block or inhibit the thermal image from appearing a pigmented ink layer. However, it is to be understood that if pigmented inks are reduced in strength, or diluted, it is anticipated that such reduced pigmented inks could also be used in practicing the method of the present invention instead of, or in addition to, using dye resin inks. By sufficiently reducing the strength or density of the colored pigment in pigmented inks, light color shading of the thermal paper is achievable, and thermal imaging should appear through the reduced pigmented inks in a manner similar to thermal imaging produced using dye resin inks.
[0030] While preferred embodiments of the invention have been described using specific terms, such description is for present illustrative purposes only, and it is to be understood that changes and variations to such embodiments, including but not limited to the substitution of equivalent features or parts, and the reversal of various features thereof, may be practiced by those of ordinary skill in the art without departing from the spirit or scope of the present disclosure.
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A dye resin ink application process using flexographic printing, flood coating, tinting, or other suitable technique or process to add a color layer on top of a thermal ink layer of a material. The color layer provides a background color, such that upon application of the heat source, the thermal image appears as being imaged onto the background color. The process can be used to make heat-sensitive direct thermal labels or thermal paper rolls, including cash register-type rolls, poster printer format rolls, etc. The process permits thermal-inked material to be produced in various colors in relatively small print runs using conventional equipment.
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FIELD OF THE INVENTION
This invention relates to improved electrical resistance heaters.
BACKGROUND OF THE INVENTION
Electrical resistance heaters suitable for heating long intervals of subterranean earth formations have been under development for many years. These heaters have been found to be useful for carbonizing hydrocarboncontaining zones for use as electrodes within reservoir formations, for enhanced oil recovery and for recovery of hydrocarbons from oil shales. U.S. Pat. No. 2,732,195 discloses a process to create electrodes utilizing a subterranean heater. The heater utilized is capable of heating an interval of 20 to 30 meters within subterranean oil shales to temperatures of 500° C. to 1000° C. Iron or chromium alloy resistors are utilized as the core heating element. These heating elements have a high resistance and relatively large voltage is required for the heater to extend over a long interval with a reasonable heat flux. It would be preferable to utilize lower resistance material. Further, it would be preferable to use a material which is malleable to permit more economical fabrication of the heater.
Subterranean heaters having copper core heating elements are disclosed in U.S. Pat. No. 4,570,715. This core has a low resistance, which permits heating long intervals of subterranean earth with a reasonable voltage across the elements. Further, because copper is a malleable material, this heater is much more economical to fabricate. These heaters can heat 1000-foot intervals of earth formations to temperatures of 600° C. to 1000° C. with 100 to 200 watts per foot of heating capacity with a 1200 volt power source. But copper also has shortcomings as a material for a heating element. As the temperature of a copper heating element increases, the electrical resistance increases at a rate which is undesirably high. If a segment of the heating coil becomes excessively hot, the increase in electrical resistance of the hot segment causes a cascading effect which can result in failure of the element.
A subterranean heater utilizing an electric resistant heater element having a lower temperature coefficient of resistance would not only improve temperature stability, but would simplify the power supply circuitry.
It is therefore the object of the present invention to provide an improved heater capable of heating long intervals of subterranean earth wherein the heating element has a low temperature coefficient of resistance, a low electrical resistance, and utilizes a core of a malleable metal material.
SUMMARY OF THE INVENTION
The object of the present invention is accomplished by providing a heater having a long heating element, the heater comprising:
a) at least one electrical heating cable which comprises a core comprising about 6 percent by weight of nickel and about 94 percent by weight of copper; and
b) a means for supplying electrical current through the electrical heating cable.
When this copper-nickel alloy is incorporated into such a heater cable the benefits of a low resistance heater are obtained along with the benefit of having a low temperature coefficient of resistance. The heater cable material is also malleable. Such a heater can therefore be utilized to heat subterranean intervals of earth to temperatures of 500° C. to 1000° C. utilizing voltages in the range of 400 to 1000 Volts.
These heater coils are less likely to fail prematurely because the resistance of the cable in hot segments is much nearer to the resistance of the remaining coil. Hot spots therefore have less tendency to continue to increase in temperature due to higher electrical resistance, causing premature failure. The electrical resistance of the element also varies less between the initial cool state and the service temperatures which simplifies the power supply circuitry. The benefits of the low resistance and low temperature coefficient of resistance heater element of the present invention are most significant when the heater is one which applies heat over large intervals of subterranean earth and at a temperature level of 600° C. to 1000° C. lntervals of 1000 feet or more can be heated with these heaters.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic illustration of a heater of the present invention being installed within a well.
FIG. 2 is a three-dimensional illustration of an insulated and sheathed heating element of the present invention.
FIG. 3 is a cross-sectional illustration of power cable to heating cable splice of the present invention.
FIG. 4 is a cross-sectional illustration of the heating cable bottom terminal plug.
FIG. 5 is a three-dimensional illustration of an insulated and sheathed heating element of the present invention having two cores.
FIG. 6 is a three-dimensional illustration of an insulated and sheathed heating element of the present invention having three cores.
DETAILED DESCRIPTION OF THE INVENTION
The heater of this invention is any heater wherein a long element is utilized. The long element necessitates the use of a material which has a low electrical resistance. Copper is such a material, but copper is prone to forming hot spots due to its high temperature coefficient of resistance. An alloy of about 6 percent by weight nickel and 94 percent by weight copper, known as LOHM, has both a relatively low resistance, and a low temperature coefficient of resistance. This results in a more simple power supply circuitry, and less of a tendency to form hot spots. The long element heaters of this invention can be utilized in subterranean oil recovery or coal shale hydrocarbon recovery. These types of heaters are often referred to as well heaters.
A preferred basic heater design for the practice of this invention is described in U.S. Pat. No. 4,570,715, incorporated herein by reference. The well heaters may be of other designs because the present invention is broadly an Improved heater core metallurgy which can be utilized in numerous long heater designs.
The reason for the decreased tendency to form "hot spots" which result in premature heater core failures can be seen from comparing the "normalized resistance" of different potential heater core materials. The normalized resistance is the resistance of a metal at a temperature divided by the resistance of that metal at room temperature. Because resistances of metal change almost linearly with temperature, a metal with a lower normalized resistance at an elevated temperature will have a much lower relative change in heat output if the temperature of the core increases. Normalized resistance of nickel and copper at 800° C. are about 5.8 and about 4.8, respectively. The normalized resistance of "30 Alloy" at 800° C. is about 2.2. The normalized resistance at 800° C. of an alloy of 6% nickel and the balance copper is only about 1.5. This reflects a significant advantage in expected heater core life.
Nichrome alloy also has an excellent normalized resistance. At 800° C. the normalized resistance is only about 1.12. But, the electrical resistance is over three times that of nickel at 800° C., and about 27 times that of copper. Nichrome is also not a malleable metal. In spite of the very low normalized resistance of Nichrome, its high resistance and lack of malleability render it undesirable as a long heater core metal.
In a preferred embodiment of the present invention the heater is a well heater with a heater core inside a metal sheath. The heater core and metal sheath are separated by a space, and the space is packed with mineral insulation material. The uphole ends of the sheathed heating element cables are connected to power supply cables. Power supply cables are heat-stable similarly insulated and sheathed cables containing cores having ratios of cross-sectional area to resistance making them capable of transmitting the current flowing through the heating elements while generating heat at a significantly lower rate. The power supply cables are preferably copper sheathed, mineral insulated, and copper cored, and have cross-sectional areas large enough to generate only an insignificant amount of heat while supplying all of the current needed to generate the selected temperature in the heated zone.
Splices of the cores in cables in which mineral insulations and metal sheaths encase current-conducting cores are preferably surrounded by relatively short lengths of metal sleeves enclosing the portions in which the cable cores are welded together or otherwise electrically interconnected. Such electrical connections should provide joint resistance a least as low as that of the least electrically resistive cable core being joined. Also, an insulation of particulate material having properties of electrical resistivity, compressive strength, and heat conductance at least substantially equalling those of the cable insulations, is preferably compacted around the cores which are spliced.
FIG. 1 shows a well, 15, which extends through a layer of "overburden" and zones 1 and 2 of an earth formation. Zone 2 is a zone which is to be heated.
As seen from the top down, the heater assembly consists of a pair of spoolable electric power supply cables 1 and 2, an optional thermowell 3. A thermocouple, 4, is suspended by a thermocouple wire 5, and held taut by a sinker bar, 6. The thermocouple may be raised or lowered by rotating a spool, 7. The preferred embodiment is to cement the heating cables direct in place, as shown in FIG. 1. In the preferred heater, the casing does not extend to the zone which the heater is to heat. At the interface of the zone which is to be heated, zone Z, and the zone which is not to be heated, zone 1, power supply cables, 1 and 2, are spliced to heater cables, 9 and 10, through splices, 11 and 12. The heating cables extend downward to the bottom of the zone to be heated. At the bottom of the heating cables the heater cores are grounded to the cable sheaths with termination plugs, 13. The termination plugs may be electrically connected by a means such as the coupler, 12.
The thermowell, power supply cable and heating cables may be suspended within a casing. If they are suspended within a casing, the bottom of the casing should be sealed to prevent liquids from entering. Liquids present within the casing in the zone to be heated would limit the temperatures which could be achieved due to the liquids vaporizing, rising up the casing, and condensing in the casing above the heating cables. The condensed liquids would then fall down to the heating cables, thus preventing high temperatures from being achieved. The preferred embodiment, as illustrated in FIG. 1, does not include a casing in the zone to be heated. The heating cables and thermowell are cemented in the borehole. When the heating cable is cemented in the borehole, the heating cable sheath must be a material that will protect the heating cab-e from corrosion due to the exposure of the heating cable to subterranean elements.
Cementing the thermowell and heating cable into the borehole, and eliminating at least this portion of the casing, reduces the expense of the installation considerably. 1: a casing is used, it must be fabricated from expensive materials due to the high temperature and corrosive environment. Heat transfer is also improved when the casing is eliminated due to the absence of the vapor space around the heating cab-e. A smaller diameter well hole can also be utilized. The smaller diameter hole may result in less cement being required to cement the heating cables than what would be required to cement a casing into a borehole along with reducing drilling costs. The problems involved with hermetically sealing the casing to exclude liquids from entering are also avoided by elimination of the casing. Cementing the heating cables directly into the borehole also eliminates thermal expansion and creep by securing the heating cables into their initial positions.
FIGS. 2, 5, and 6 display one, two, and three cored heating cables, respectively, in a preferred structural arrangement of the heating and power supply cables. Referring to FIGS. 2, 5 and 6 an electrically conductive core, 100, is cores 100, are surrounded by an annular mass of compressed mineral insulating material, 101, which is surrounded by a metal sheath, 102. The metal sheath may optionally be fabricated in two layers (not shown). A relatively thin inner layer may be fabricated initially, and a thicker outer layer of a material resistant to corrosion could then be added in a separate step.
FIG. 3 displays details of the splice 9, of FIG. 1. The power supply cable consisting of the electrical conductive core, 100, is surrounded by compressed mineral insulation, 101, covered by a sheath, 102. The electrical conductive core of the power supply cable is preferably copper and is of a sufficiently large cross-sectional area to prevent a significant amount of heat from being generated under operating conditions. The sheath of the power supply cable is preferably copper. A transition sheath, 103, extends up from the coupled end of the power supply cable in order to protect the sheath from corrosion due to the elevated temperature near the heating cable. This protective sheath is preferably the same material as the sheathing material of the heating cable. The protective sheathing could extend for a distance of between a few feet to over 40 feet. A distance of about 40 feet is preferred. This distance ensures that the power supply cable is not damaged as a result of exposure to high temperatures in the vicinity of the heating cables.
In FIG. 3, the heating cable sheath is shown as the preferred two-layer sheath of an inner sheath, 108, and an outer sheath, 107. The core of the heating cable, 104, is welded to the power supply cable core, 100. The heating cable is of a cross section area and resistance such as to create from 50 to 250 watts per foot of heat at operating currents. The coupling sleeve, 105, and compression sleeve, 106, are slid onto either the power supply cable or heating cable prior to the cores of the cables being welded. After the cores are welded together, the coupling sleeve, 105, is welded into place onto the power supply cable. The space around the power supply cable core to heating cable core is then filled with a mineral insulating material. The mineral insulating material is then compressed by sliding the compression sleeve, 106, into the space between the sleeve coupling and the heating cable. After the compression sleeve is forced into this space, it is sealed by welded connections to the heating cable outer sheath, 107, and the coupling sleeve.
For use in the present invention, the diameter and thickness of the sheath is preferably small enough to provide a cable which is "spoolable", i.e., can be readily coiled and uncoiled from spools without crimping the sheath or redistributing the insulating material. The diameter of the electrically conductive core within the cable can be varied to allow different amounts of current to be carried while generating significant or insignificant amounts of heat, depending upon whether the conductive core is a heating cable or a power supply cable.
When the heating cable is utilized in a well with a casing, the sheath of the heating cable is preferably a single layer sheath of 316 stainless steel or the equivalent. When the heating cable is cemented directly into the borehole without a casing, a double layer sheath is preferred. The inner layer and the outer layer are both preferably INCOLOY 800®. A total sheath thickness of about one-quarter inch is preferred although a thickness of from one-eighth inch to one-half inch can be acceptable depending upon the service time desired, operating temperatures, and the corrosiveness of the operating environment.
FIG. 3 displays a one core element, but it is most preferred that the cable be fabricated with two or three cores. The multiple cores can each carry electricity, and eliminate the need for parallel heating and power supply cables. A single-phase alternating current power supply requires two cores per cable in the most preferred embodiment of this invention, and a three-phase alternating power supply requires three cores per cable.
The heating cable cores are preferably grounded at the extremity of the heating cable opposite the end of the heating cable which is coupled to the power supply cables. FIG. 1 includes the preferred termination plugs, 13, connected by an electrically conductive end coupler, 12. FIG. 4 displays the preferred termination plug. The plug, 13, is forced into a termination sleeve, 19, which had been previously welded onto the sheath of the power supply cable, 107. The termination plug is forced into the sleeve to compress the mineral insulating material, 101. The termination plug is then brazed onto the heating cable core, 104, and welded to the termination sleeve. The termination plugs on each heating cable may be clamped together, as shown in FIG. 1. When a heating cable with multiple cores is utilized, the termination plug has a hole for each, and the plug serves to electrically connect the cables.
The use of LOHM as the heater cable core material significantly simplifies power circuitry by permitting zero crossover rather than phase angle control of electrical current to the heater. The prior art copper cored heater cables have a large difference between hot and cold resistances, and therefore large differences between hot and cold electrical current requirements for similar amounts of heat output.
Zero crossover electrical heater firing control is achieved by allowing full supply voltage to pass through the heating cable for a specific number of cycles, starting at the "crossover", where instantaneous voltage is zero, and continuing for a specific number of complete cycles, discontinuing when the instantaneous voltage again crosses zero. A specific number of cycles are then blocked, allowing control of the heat output by the heating cable. The system may be arranged to "block" 15 or 20 cycles out of each 60. This control is not practical when the circuitry must be sized for a resistance that varies significantly because this varying resistance would cause the current required to vary excessively. Zero crossover heater firing is therefore not practical with prior art copper core heaters, but is generally acceptable with a LOHM core heater. The alternative firing control which is required by prior art copper core heaters is phase angle firing. Phase angle firing passes a portion of each power cycle to the heater core. The power is applied with a non-zero voltage and continues until the voltage passes to zero. Because voltage is applied to the system starting with a voltage differential, a considerable spike of amperage occurs, which the system must be designed to handle. The zero crossover power control is therefore generally preferred, and systems which may incorporate zero crossover power control are advantageous.
A thermowell may be incorporated into a well borehole which incorporates the heater of the present invention. The thermowell may be incorporated into a well either with or without a casing. When the well does not include a casing, the thermowell must be of a metallurgy and thickness to withstand corrosion by the subterranean environment. A thermowell and temperature logging process such as that disclosed in U.S. Pat. No. 4,616,705 is preferred. Due to the expense of providing a thermowell and temperature sensing facilities, it is envisioned that only a small number of thermowells would be provided in heating wells within a formation to be heated.
Subterranean earth formations which contain varying thermal conductivities may require segmented heating cables, with heat outputs per foot adjusted to provide a more nearly constant well heater temperature profile. Such a segmented heater is described in U.S. Pat. No. 4,570,715. The greatly reduced tendency of LOHM core well heaters to develop hot spots greatly reduces the need for the well heater core to have a heat output which is correlated with local variations in subterranean thermal conductivities, but the technique of segmenting the heater coil may be beneficial, and required to reach maximum heat inputs into specific formations.
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An electrical resistance heater is provided which utilizes a copper-nickel alloy heating cable. This metallurgy heating cable is significantly less prone to failure due to localized overheating because the alloy has a low temperature coefficient of resistance. Used as a well heater, the heating cable permits heating of long segments of subterranean earth formation with a power supply of 400 to 1200 volts.
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TECHNICAL FIELD
[0001] The technical field of the present disclosure relates to substrate processing and load locks, more particularly to systems and methods that transfer substrates to and from a processing chamber or reactor and to and from a load lock.
BACKGROUND ART
[0002] When processing one or more substrates in a reactor, such as a chemical vapor deposition reactor, a load lock is generally employed. A load lock functions similarly to an airlock, and serves to prevent cross-contamination between an ambient environment and the reactor environment. The load lock holds one or more substrates, which are transferred from the load lock into the reactor for processing. Some systems have two load locks, one on either side of the reactor, and the second load lock receives wafers or other substrates from the reactor after processing. Such systems have a unidirectional substrate flow, as the substrates are moved from one load lock into the reactor for processing, and then from the reactor to the other load lock after processing. Each load lock employs an isolation seal, such as a door or a gate or other isolation device such as a gas curtain, between the load lock and the reactor. The other side of the load lock also employs an isolation seal, separating the load lock from either the ambient environment or a load and unload unit. The isolation seals can support pressure and/or temperature differences from one chamber or unit to the next. Load and unload units can be robotic in nature and provide automated loading and unloading of load locks.
[0003] Types of substrates eligible for processing in a reactor include both glass, e.g. as used in flat-panel displays, and semiconductor wafer substrates, such as those used to make solar photovoltaic cells or integrated circuits. Substrates may be mounted in a substrate carrier or on a susceptor. The substrates can be processed individually or in groups, depending on substrate size, reactor chamber size, processing sequence and other factors. Substrates can be moved using a transport mechanism, which can include a conveyor belt, one or more shuttles operated individually or in a train, rollers, air or other gas levitation, or magnetic coupling.
[0004] A reactor can include one or more processing chambers, and may perform one or more types of semiconductor processing steps such as diffusion, etching, deposition, or cleaning. Often, the amount of time substrates spend in the reactor, being processed, is the major factor affecting processing throughput and operating efficiency of a system. Reactor idle time, during which the reactor is not applying processing, reduces throughput and operating efficiency. Reactor idle time may occur while the reactor is waiting for wafers to be preheated, waiting for wafers be cooled, waiting for wafers to be moved into or out of the reactor and at other waiting times. Improvements in processing throughput and operating efficiency of systems using reactors for substrate processing are sought.
SUMMARY
[0005] A method for operating a hot reactor between two load locks, and a related system for substrate processing are disclosed herein. The method and system are suitable for processing various substrates singly or in groups. Concurrent transfers of substrates from the reactor to the first load lock and from the second load lock to the reactor are interleaved with concurrent transfers of substrates from the reactor to the second load lock and from the first load lock to the reactor.
[0006] In an embodiment of the method, a hot reactor has two load locks. Substrates are concurrently moved from the reactor to a second load lock and from a first load lock into the reactor, in transfers in a first direction. Further substrates are concurrently moved from the reactor to the first load lock and from the second load lock into the reactor, in transfers in a second direction. The transfers in the first direction are interleaved with the transfers in the second direction, during a continuous operation of the reactor and the first and second load locks. The interleaved transfers minimize or make zero the reactor idle time. The substrates and the further substrates are transferred and processed individually or in groups.
[0007] More specifically, a hot reactor is located between two load locks. A processed first substrate is moved from the reactor to the first load lock. Concurrently with this move, a heated second substrate is moved from the second load lock to the reactor. The first substrate is cooled in the first load lock. The cooled first substrate is unloaded from the first load lock. A third substrate is loaded into the first load lock. The third substrate is heated in the first load lock. Substrate processing is applied to the second substrate in the reactor. The substrate processing is applied while the first substrate is being cooled in and then unloaded from the first load lock and the third substrate is being loaded into the first load lock and heated therein. The processed second substrate is moved from the reactor to the second load lock. Concurrently with this move, the heated third substrate is moved from the first load lock to the reactor. The second substrate is cooled in the second load lock. The cooled second substrate is unloaded from the second load lock. A fourth substrate is loaded into the second load lock. The fourth substrate is heated in the second load lock. Further substrate processing is applied to the third substrate in the reactor. The substrate processing is applied while the second substrate is being cooled in and then unloaded from the second load lock and the fourth substrate is being loaded into the second load lock and heated therein. A processing duration as applied to substrates being processed in the reactor is greater than an unload duration as applied to unloading substrates from the load locks plus a load duration is applied to loading substrates into the load locks. A cycle time of processing multiple such substrates is reduced and a throughput is increased as compared to using only a single load lock with the reactor.
[0008] The system for substrate processing includes a reactor, first and second load locks, first and second load and unload units and a bidirectional transfer mechanism. The first and second load locks are both connected to the reactor, can heat substrates therein before the substrates are moved into the reactor, and can also cool substrates after they are moved from the reactor. The first and second load and unload units are connected to the respective first and second load locks so as to be able to load and unload substrates into and out of those load locks. The bidirectional transfer mechanism can, in a first transfer direction, concurrently transfer (1) heated substrates from the first load lock into the reactor and (2) processed substrates from the reactor into the second load lock. Likewise, the bidirectional transfer mechanism can, in a second transfer direction, concurrently transfer (1) heated substrates from the second load lock into the reactor and (2) processed substrates from the reactor into the first load lock.
[0009] In an alternate embodiment, there can be two parallel reactor systems, each with their own sets of load and unload units and load locks, but both sharing a common gas box and related plumbing to supply the process gas to the respective reactors. In such a case, it may be advantageous to stagger the load-process-unload cycles of the parallel reactor systems so that the reactors do not require simultaneous use of the shared gas box.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIGS. 1-16 are schematic diagrams showing interleaved transfers of substrates in a reactor-based system for substrate processing, in accordance with the present invention. The system includes a central reactor, two load locks and two load and unload units.
[0011] FIG. 17 is a timing diagram showing in the upper half of the diagram the operation of the reactor-based system of FIG. 1 .
[0012] FIG. 18 is a schematic diagram of a further embodiment of a reactor-based system, as in FIG. 1 but including two reactors, four load locks and four load and unload units. FIG. 17 further shows, in both upper and lower halves of the diagram, staggered operation of this embodiment.
DETAILED DESCRIPTION
[0013] As shown in FIGS. 1-18 , embodiments of a reactor-based system 100 for substrate processing and a related method of operation thereof achieve high efficiency and substrate processing throughput. Transfers of substrates are coordinated in an interleaved manner so that idle time for the reactor is minimized or made zero, thus improving efficiency and throughput. In particular, preheating and post-process cooling of substrates take place inside load locks at the same time that processing of another substrate is performed within the reactor. Transfers into and out of the reactor occur concurrently through separate load locks.
[0014] With reference to FIG. 1 , the reactor-based system 100 for substrate processing includes a reactor 106 . Examples of suitable reactors include chemical vapor deposition reactors, showerhead reactors and semiconductor processing reactors. A first load lock 104 and a second load lock 108 are connected to opposite sides of the reactor 106 , although other arrangements may be used. A first load and unload unit 102 is connected to the first load lock 104 . A second load and unload unit 110 is connected to the second load lock 108 . Respective isolation seals 112 , 114 , 116 , 118 , 120 , 122 can be individually opened or closed to allow passage of substrates or isolate neighboring units in support of differing pressures and/or temperatures.
[0015] The embodiment of FIG. 1 has a linear arrangement of the first load and unload unit 102 , the first load lock 104 , the reactor 106 , the second load lock 108 and the second load and unload unit 110 , although other arrangements can be used in further embodiments. A first (optional) isolation seal 112 isolates one end of the first load and unload unit 102 from the ambient environment or further equipment, or selectively opens thereto: A second isolation seal 114 opens to connect or seals to isolate the first load and unload unit 102 and the first load lock 104 . A third isolation seal 116 opens to connect or seals to isolate the first load lock 104 and the reactor 106 . A fourth isolation seal 118 opens to connect or seals to isolate the reactor 106 and the second load lock 108 . A fifth isolation seal 120 opens to connect or seals to isolate the second load lock 108 and the second load and unload unit 110 . A sixth (optional) isolation seal 122 seals one end of the second load and unload unit 110 from the ambient environment or further equipment, or selectively opens thereto.
[0016] In sequence, FIGS. 1-16 show substrates being moved in an interleaved manner in a cycle of transfers involving the reactor 106 , the first and second load locks 104 , 108 and the first and second load and unload units 102 , 110 . In an ongoing or continuous process flow, the cycle of FIGS. 1-16 is repeated continuously. Initial steps for bringing up the system from a cold, unloaded state are not shown, and are readily devised. Such initial steps include initial loading of either or both of the load and unload units 102 , 110 , initial transfer to one of the load locks 104 , 108 , and loading of a substrate or group of substrates into the reactor 106 for the initial processing.
[0017] FIG. 1 starts the cycle from a steady state of operation. A group of processed substrates 124 (shown with diagonal shading bars) is present in the reactor 106 . A group of substrates (shown with dotted shading) 126 is present in the second load lock 108 , awaiting their turn for processing in the reactor 106 . The substrates 126 may be unprocessed or preprocessed substrates, i.e. the substrates 126 have not yet received the next processing in the reactor 106 , but may have received previous processing. Isolation seals 114 , 120 between the load locks 104 , 108 and the load and unload units 102 , 110 are closed, and isolation seals 116 , 118 at opposed sides of the reactor 106 , i.e. between the reactor 106 and the load locks 104 , 108 are opened. The reactor 106 and the load locks 104 , 108 are pressure equalized and heated to a uniform, elevated temperature (shown as square grid shading), for example 400° C. Heating may be accomplished by convection, conduction or radiation, by using an electric heating element, heating lamps or other heat source. In the example shown, the substrates are in a group of three subgroups of sixteen substrates each, with each subgroup of sixteen substrates as four groups of four substrates. In further examples, a single substrate could be in the reactor 106 and a further single substrate could be in the second load lock 108 , or other groups of substrates could be used. Multiple substrates may be moved on a carrier. Multiple carriers may be moved together in a group and processed in a chamber.
[0018] FIG. 2 follows FIG. 1 in the cycle. The processed substrates 124 and the substrates 126 that await processing are both moved concurrently in a two-one direction 230 (leftward in the drawing), for example by a transport mechanism that moves the substrates simultaneously. The processed substrates 124 are moved from the reactor 106 to the first load lock 104 , and the substrates 126 are moved from the second load lock 108 to the reactor 106 . In FIG. 2 , the isolation seals 114 , 116 , 118 , 120 and temperature equalizing remain as in FIG. 1 . The concurrent moving of substrates out of and into the reactor 106 minimizes the reactor idle time. By comparison, sequentially moving the processed substrates 124 from the reactor to the first load lock 104 , followed by moving the substrates 126 awaiting processing from the second load lock 108 to the reactor 106 would add to the reactor idle time because of the delay between the two sequential moves.
[0019] In FIG. 3 , the isolation seals 116 , 118 between the reactor 106 and the load locks 104 , 108 are closed, which support differing pressures and/or temperatures. Isolation seals 114 , 120 between the load locks 104 , 108 and the respective load and unload units 102 , 110 remained closed. The processed substrates 124 are being cooled in the first load lock 104 (shown as horizontal shading bars). Cooling may be accomplished by air cooling, gas cooling or liquid cooling, for example by circulating a cooling liquid through passages in a plate. The load lock 104 is being filled with gas, for example nitrogen, to raise the pressure to match that of the load and unload unit 102 . Alternatively, load lock 104 can be cycle purged to reduce residual process gas species from reactor 106 prior to raising the pressure to match that of the load and unload unit 102 . The substrates 126 in the reactor are being heated to a further elevated temperature (shown as vertical shading bars), for example 800° C.
[0020] FIG. 4 shows the substrates 126 receiving processing and becoming processed substrates 426 in the reactor 106 , under the same temperature conditions as shown in FIG. 3 .
[0021] In FIG. 5 , the processed substrates 124 that were moved out of the reactor 106 in FIG. 2 and cooled in the first load lock 104 are now moved from the first load lock 104 to the first load and unload unit 102 . The isolation seal 114 between the first load and unload unit 102 and the first load lock 104 is open to permit passage of the processed substrates 124 , and the first load and unload unit 102 and the first load lock 104 are at equal pressure, for example, atmospheric pressure (shown without shading). The substrates becoming processed substrates 426 continue to receive processing in the reactor 106 , which remains at the further elevated temperature. The second load lock 108 remains at the elevated temperature. The isolation seals 116 , 118 between the reactor 106 and the load locks 104 , 108 remain closed, supporting the pressure and/or temperature difference.
[0022] In FIG. 6 , the processed substrates 124 in the first load and unload unit 102 are exchanged for substrates 624 , which may be unprocessed or preprocessed substrates. This is accomplished using a substrate handler, a robotic handler, or other automated or manual unloading of the processed substrates 124 and loading of the substrates 624 . The substrates becoming processed substrates 426 continue to receive processing in the reactor 106 , which remains at the further elevated temperature. The second load lock 108 remains at the elevated temperature. The isolation seals 116 , 118 between the reactor 106 and the load locks 104 , 108 remain closed, supporting the pressure and/or temperature difference.
[0023] In FIG. 7 , the substrates 624 are moved from the first load and unload unit 102 into the first load lock 104 . The isolation seal 114 between the first load and unload unit 102 and the first load lock 104 is open to permit passage of the substrates 624 , and the first load and unload unit 102 and the first load lock 104 are at equal pressure (shown without shading). The substrates becoming processed substrates 426 continue to receive processing in the reactor 106 , which remains at the further elevated temperature. The second load lock 108 remains at the elevated temperature. The isolation seals, 116 , 118 between the reactor 106 and the load locks 104 , 108 remain closed, supporting the pressure and/or temperature difference.
[0024] In FIG. 8 , the isolation seals 116 , 118 between the reactor 106 and the load locks 104 , 108 are closed, which support differing pressures and/or temperatures. Isolation seals 114 , 120 between the load locks 104 , 108 and the respective load and unload units 102 , 110 are closed. The processed substrates 426 are being cooled in the reactor 106 (shown as horizontal shading bars). Cooling may be accomplished by reducing the power input to the reactor heater. The substrates 624 in the first load lock 104 are being heated to an elevated temperature (shown as vertical shading bars), for example 400° C. The load lock 104 is being evacuated to lower the pressure to match that of the reactor 106 . Alternatively, load lock 104 can be cycle purged to reduce residual contaminant gas species from the load and unload unit 102 prior to lowering the pressure to match that of reactor 106 .
[0025] FIG. 9 shows the isolation seals 114 , 120 between the load locks 104 , 108 and the load and unload units 102 , 110 are closed, and the isolation seals 116 , 118 between the reactor 106 and the load locks 104 , 108 are opened to support passage of substrates. The reactor 106 and the load locks 104 , 108 are pressure equalized and at a uniform, elevated temperature (shown as square grid shading), for example 400° C. The processed substrates 426 are no longer receiving processing in the reactor 106 .
[0026] In FIG. 10 , the processed substrates 426 and the substrates 624 awaiting processing are both moved concurrently in a one-two direction 930 (rightward in the drawing), for example by a transport mechanism that moves the substrates simultaneously. The processed substrates 426 are moved from the reactor 106 to the second load lock 108 , and the substrates 624 are moved from the first load lock 104 to the reactor 106 . In FIG. 10 , the isolation seals 114 , 116 , 118 , 120 and temperature equalizing remain as in FIG. 9 . The concurrent moving of substrates out of and into the reactor 106 minimizes the reactor idle time.
[0027] In FIG. 11 , the isolation seals 116 , 118 between the reactor 106 and the load locks 104 , 108 are closed, which supports differing pressures and/or temperatures. Isolation seals 114 , 120 between the load locks 104 , 108 and the respective load and unload units 102 , 110 remained closed. The processed substrates 426 are being cooled in the second load lock 108 (shown as horizontal shading bars). Cooling may be accomplished by air cooling, gas cooling or liquid cooling, for example by circulating a cooling liquid through passages in a plate. The load lock 108 is being filled with gas, for example nitrogen, to raise the pressure to match that of the load and unload unit 110 . Alternatively, load lock 108 can be cycle purged to reduce residual process gas species from reactor 106 prior to raising the pressure to match that of the load and unload unit 110 . The substrates 624 in the reactor are being heated to a further elevated temperature (shown as vertical shading bars), for example 800° C.
[0028] FIG. 12 shows the substrates 624 receiving processing and becoming processed substrates 1124 in the reactor 106 , under the same temperature conditions as shown in FIG. 11 .
[0029] In FIG. 13 , the processed substrates 426 that were moved out of the reactor 106 in FIG. 10 and cooled in the second load lock 108 are moved from the second load lock 108 to the second load and unload unit 110 . The isolation seal 120 between the second load and unload unit 110 and the second load lock 108 is open to permit passage of the processed substrates 426 , and the second load and unload unit 110 and the second load lock 108 are at equal pressure (shown without shading). The substrates becoming processed substrates 1124 continue to receive processing in the reactor 106 , which remains at the further elevated temperature. The first load lock 104 remains at the elevated temperature. The isolation seals 116 , 118 between the reactor 106 and the load locks 104 , 108 remain closed, supporting the pressure and/or temperature difference.
[0030] In FIG. 14 , the processed substrates 426 in the second load and unload unit 110 are exchanged for substrates 1326 , which may be unprocessed or preprocessed substrates. This is accomplished using a substrate handler, a robotic handler, or other automated or manual unloading of the processed substrates 426 and loading of the substrates 1326 . The substrates becoming processed substrates 1124 continue to receive processing in the reactor 106 , which remains at the further elevated temperature. The first load lock 104 remains at the elevated temperature. The isolation seals 116 , 118 between the reactor 106 and the load locks 104 , 108 remain closed, supporting the pressure and/or temperature difference.
[0031] In FIG. 15 , the substrates 1326 are moved from the second load and unload unit 110 into the second load lock 108 . The isolation seal 120 between the second load and unload unit 110 and the second load lock 108 is open to permit passage of the substrates 1326 , and the second load and unload unit 110 and the second load lock 108 are at equal pressure (shown without shading). The substrates becoming processed substrates 1124 continue to receive processing in the reactor 106 , which remains at the further elevated temperature. The first load lock 104 remains at the elevated temperature. The isolation seals 116 , 118 between the reactor 106 and the load locks 104 , 108 remain closed, supporting the pressure and/or temperature difference.
[0032] In FIG. 16 , the isolation seals 116 , 118 between the reactor 106 and the load locks 104 , 108 are closed, which support differing pressures and/or temperatures. Isolation seals 114 , 120 between the load locks 104 , 108 and the respective load and unload units 102 , 110 are closed. The processed substrates 1124 are being cooled in the reactor 106 (shown as horizontal shading bars). Cooling may be accomplished by reducing the power input to the reactor heater. The substrates 1326 in the second load lock 108 are being heated to an elevated temperature (shown as vertical shading bars), for example 400° C. The load lock 108 is being evacuated to lower the pressure to match that of the reactor 106 . Alternatively, load lock 108 can be cycle purged to reduce residual contaminant gas species from the load and unload unit 110 prior to lowering the pressure to match that of reactor 106 . In an ongoing, continuous operation, FIG. 1 would follow FIG. 16 , and the reactor would continue to receive substrates alternately from the first and second load locks, with interleaved concurrent transfers. The reactor would continue to move processed substrates alternately to the first and second load locks, with the interleaved concurrent transfers.
[0033] With reference to FIG. 17 , a timing diagram 1700 is shown. The timing diagram 1700 shows an embodiment of an operation of the reactor-based system 100 , as discussed below, and further shows an embodiment of an operation of the reactor-based system 1800 as will be discussed following presentation of FIG. 18 .
[0034] From top to bottom, the timing diagram 1700 shows operation of components of the reactor-based system 100 . A first region 1702 of the timing diagram 1700 shows operation of the first load and unload unit 102 . A second region 1704 shows operation of the first load lock 104 . A third region 1706 shows operation of the reactor 106 , which may also be called the first reactor in a further embodiment. A fourth region 1708 shows operation of the second load lock 108 . A fifth region 1710 shows operation of the second load and unload unit 110 . The regions 1712 - 1720 show operations of a parallel system as considered below with reference to FIG. 18 . Each of the regions 1702 - 1710 will now be described individually as they relate to the others, which complements the event-driven description of the reactor-based system 100 as described above with reference to FIGS. 1-16 .
[0035] Starting with the first load and unload unit 102 , from time zero on the timing diagram 1700 , the unit 102 is initially idle or at least not involved in any transfers to or from the first load lock 104 . Next, there is a transfer 1721 of processed substrates from the first load lock 104 to the first load and unload unit 102 . Next, there is an index operation 1722 . Next, there is a transfer 1723 of unprocessed or preprocessed substrates from the first load and unload unit 102 to the first load lock 104 . Next there is a load and unload operation 1724 in the first load and unload unit 102 , in which the processed substrates are unloaded and unprocessed or preprocessed substrates are loaded in preparation for the next transfer towards the reactor 106 , i.e. a subsequent transfer from the first load and unload unit 102 to the first load lock 104 . For the remainder of the time on the timing diagram 1700 , the first load and unload unit 102 is idle or at least not involved in any transfers to or from the first load lock 104 . The cycle then repeats (not shown).
[0036] Turning to the first load lock 104 , from time zero on the timing diagram 1700 , the first load lock 104 is performing a vent and/or cooling operation 1725 on processed substrates recently received from the reactor 106 . Next, there is the transfer 1721 of the now cooled processed substrates from the first load lock 104 to the first load and unload unit 102 . Next, there is the transfer 1723 of unprocessed or preprocessed substrates from the first load and unload unit 102 to the first load lock 104 . Next, the substrates in the first load lock 104 awaiting processing are heated 1726 , e.g. to 400° C. This may be performed by using a heating device or a heat pump. Next, after a brief idle time 1727 following the heating, there is a transfer 1728 of the now heated substrates from the first load lock 104 to the reactor 106 . This transfer 1728 is included in a concurrent transfer 1733 , discussed below. After these substrates are processed in the reactor 106 , during which time the first load lock 104 is idle or at least not involved in any transfers, there is a transfer 1729 of the substrates from the reactor 106 to the first load lock 104 . This transfer 1729 is included in a concurrent transfer 1737 , discussed below. The cycle then repeats (not shown).
[0037] Considering now the reactor 106 , from time zero on the timing diagram 1700 , the reactor 106 is heating 1730 , e.g. from 400° C. to 800° C., with substrates therein. These substrates were previously preheated, e.g. to 400° C., inside the second load lock 108 prior to being transferred into the reactor 106 . Next, the reactor performs a processing operation 1731 on, for or with the substrates, such as a chemical vapor deposition. Next, the reactor is cooled 1732 , e.g. from 800° C. to 400° C., with the processed substrates therein. Next, there is a concurrent transfer 1733 of the now processed substrates from the reactor 106 to the second load lock 108 and of the heated substrates from the first load lock 104 to the reactor 106 . Next, the heated substrates recently transferred from the first load lock 104 are further heated 1734 in the reactor 106 , e.g. from 400° C. to 800° C. Next, the reactor 106 performs a processing operation 1735 on, for or with the substrates, such as a chemical vapor deposition. Next, the reactor 106 is cooled 1736 , e.g. from 800° C. to 400° C., with the processed substrates therein. Next, there is a concurrent transfer 1737 of the now processed substrates from the reactor 106 to the first load lock 104 and of the heated substrates from the second load lock 108 to the reactor 106 . The cycle then repeats (not shown). As a result of the concurrent transfers 1733 , 1737 , the reactor experiences minimal or zero idle time.
[0038] Turning to the second load lock 108 , from time zero on the timing diagram 1700 , the second load lock 108 is idle or at least not involved in any transfers. After the substrates previously transferred from the second load lock 108 have finished being processed in the reactor 106 , there is a transfer 1738 of processed substrates from the reactor 106 to the second load lock 108 . This transfer 1738 is included in the concurrent transfer 1733 . Next, the second load lock 108 performs a vent and/or cooling operation 1739 on the processed substrates recently received from the reactor 106 . Next, there is a transfer 1740 of the now cooled processed substrates from the second load lock 108 to the second load and unload unit 110 . Next, there is a transfer 1741 of unprocessed or preprocessed substrates from the second load and unload unit 110 to the second load lock 108 . Next, the substrates in the second load lock 108 awaiting processing are heated 1742 , e.g. to 400° C. This may be performed by using a heating device or a heat pump. Next, after a brief idle time 1744 following the heating, there is a transfer 1745 of the now heated substrates from the second load lock 108 to the reactor 106 . This transfer 1745 is included in the concurrent transfer 1737 , discussed above. The cycle then repeats (not shown).
[0039] And finally, considering the second load and unload unit, from time zero on the timing diagram 1700 , the unit 110 is initially idle or at least not involved in any transfers to or from the second load lock 108 . Next, there is the transfer 1740 of processed substrates from the second load lock 108 to the second load and unload unit 110 . Next, there is an index operation 1746 . Next, there is the transfer 1741 of unprocessed or preprocessed substrates from the second load and unload unit 110 to the second load lock 108 . Next, there is a load and unload operation 1747 in the second load and unload unit 110 , in which the processed substrates are unloaded and unprocessed or preprocessed substrates are loaded in preparation for the next transfer towards the reactor 106 , i.e. a subsequent transfer from the second load and unload unit 110 to the second load lock 108 . The cycle then repeats (not shown).
[0040] Operation of the second load lock 108 and second load and unload unit 110 with respect to the reactor 106 resembles a mirror image of the operation of the first load and unload unit 102 and the first load lock 104 , except that the two sections of the reactor-based system 100 are 180 degrees or 50% out of phase with each other. The concurrent transfers 1733 , 1737 are interleaved so that the reactor 106 is receiving substrates alternately from the first load lock 104 and the second load lock 108 , and is sending processed substrates alternately to the first load lock 104 and the second load lock 108 .
[0041] With reference to FIG. 18 , a further embodiment of the reactor-based system 100 for substrate processing is shown. The reactor-based system 1800 includes two parallel reactor-based subsystems 1804 , 1806 sharing a common gas box 1802 , with manifolds connected thereto. Each of the subsystems 1804 , 1806 resembles the reactor-based system 100 albeit with shared plumbing for the shared gas box 1802 . Subsystem 1804 includes a first load and unload unit 1810 connected to a first load lock 1812 and a second load and unload unit 1818 connected to a second load lock 1816 . The first and second load locks 1812 , 1816 are connected to a first reactor 1814 . Subsystem 1806 includes a third load and unload unit 1820 connected to a third load lock 1822 , and a fourth load and unload unit 1828 connected to a fourth load lock 1826 . The third and fourth load locks 1822 , 1826 are connected to a second reactor 1824 . The first and second reactors 1814 , 1824 are connected to the shared gas box 1802 .
[0042] When multiple reactors 1814 , 1824 share a common gas box 1802 and associated plumbing, it may preferable that depositions or other processing operations applied by the reactors 1814 , 1824 be staggered wherever gas flows may be insufficient for simultaneous deposition. However, if the common gas box 1802 has the capacity to handle simultaneous deposition in both reactors 1814 , 1824 , then staggered flows are not needed and the depositions might even be synchronized. FIG. 17 , including now the bottom half of the figure, shows operation of the parallel dual-reactor-based system 1800 employing staggered processing operations. Moving of substrates into and out of the first and second reactors 1814 , 1824 is coordinated with staggered phasing so that the substrate processing is applied in each of the first and second reactors 1814 , 1824 in an alternating manner.
[0043] Referring back to FIG. 17 , the timing diagram 1700 shows operation of the reactor-based system 1800 . The first reactor-based subsystem 1804 includes the first load and unload unit 1810 , the first load lock 1812 , the first reactor 1814 , the second load lock 1816 and the second load and unload unit 1818 . The first reactor-based subsystem 1804 operates in accordance with the upper half of the timing diagram 1700 , as previously described regarding the single-reactor-based system 100 .
[0044] The second reactor-based subsystem 1806 operates in accordance with the lower half of the timing diagram 1700 in one embodiment, as now described. From time zero on the timing diagram 1700 , the third load and unload unit 1820 is initially idle or at least not involved in any transfers to or from the third load lock 1822 . Next, there is a transfer 1751 of processed substrates from the third load lock 1822 to the third load and unload unit 1820 . Next, there is an index operation 1752 . Next, there is a transfer 1753 of unprocessed or preprocessed substrates from the third load and unload unit 1820 to the third load lock 1822 . Next there is a load and unload operation 1754 in the third load and unload unit 1820 , in which the processed substrates are unloaded and unprocessed or preprocessed substrates are loaded in preparation for the next transfer towards the second reactor 1824 , i.e. a subsequent transfer from the third load and unload unit 1820 to the third load lock 1822 . For the remainder of the time on the timing diagram 1700 , the third load and unload unit 1820 is idle or at least not involved in any transfers to or from the third load lock 1822 . The cycle then repeats (not shown).
[0045] After substrates are processed in the second reactor 1824 , during which time the third load lock 1822 is idle or at least not involved in any transfers, there is a transfer 1755 of the substrates from the second reactor 1824 to the third load lock 1822 . This transfer 1755 is included in a concurrently transfer 1763 , discussed below. Next, the third load lock 1822 is performing a vent and/or cooling operation 1756 on the processed substrates recently received from the second reactor 1824 . Next, there is the transfer 1757 of the now cooled processed substrates from the third load lock 1822 to the third load and unload unit 1820 . Next, there is the transfer 1758 of unprocessed or preprocessed substrates from the third load and unload unit 1820 to the third load lock 1822 . Next, the substrates in the third load lock 1822 awaiting processing are heated 1759 , e.g. to 400° C. This may be performed by using a heating device or a heat pump. Next, after a brief idle time 1760 following the heating, there is a transfer 1761 of the now heated substrates from the third load lock 1822 to the second reactor 1824 . This transfer 1761 is included in a concurrent transfer 1767 , discussed below. The cycle then repeats (not shown).
[0046] From time zero on the timing diagram 1700 , the second reactor 1824 is cooled 1762 , e.g. from 800° C. to 400° C., with the processed substrates therein. Next, there is a concurrent transfer 1763 of the now processed substrates from the second reactor 1824 to the third load lock 1822 and of the heated substrates from the fourth load lock 1826 to the second reactor 1824 . Next, the second reactor 1824 is heating 1764 , e.g. from 400° C. to 800° C., with the recently transferred heated substrates therein. These substrates were previously heated, e.g. to 400° C., in the fourth load lock 1826 prior to being transferred to the second reactor 1824 . Next, the reactor performs a processing operation 1765 on, for or with the substrates, such as a chemical vapor deposition. Note in particular that in this staggered embodiment, the processing operation 1765 in the second reactor 1824 occurs at a different time from the corresponding processing operation 1735 in the first reactor 1814 , so that the two operations do not coincide, so that the common gas box 1802 need not have to supply process gas to both reactors at once. Next, the reactor is cooled 1766 , e.g. from 800° C. to 400° C., with the processed substrates therein. Next, there is a concurrent transfer 1767 of the now processed substrates from the second reactor 1824 to the fourth load lock 1826 and of the heated substrates from the third load lock 1822 to the second reactor 1824 . Next, the heated substrates recently transferred from the third load lock 1822 are further heated 1768 in the second reactor 1824 , e.g. from 400° C. to 800° C. Next, the second reactor 1824 performs a processing operation 1769 on, for or with the substrates, such as a chemical vapor deposition. The cycle then repeats (not shown). As a result of the concurrent transfers 1763 , 1767 , the reactor experiences minimal or zero idle time.
[0047] From time zero on the timing diagram 1700 , the substrates in the fourth load lock 1826 awaiting processing are heated 1770 , e.g. to 400° C. This may be performed by using a heating device or a heat pump. Next, there is a transfer 1771 of the now heated substrates from the fourth load lock 1826 to the second reactor 1824 . This transfer 1771 is included in the concurrent transfer 1763 , discussed above. While the substrates transferred from the fourth load lock 1826 to the second reactor 1824 are being processed in the second reactor 1824 , the fourth load lock 1826 is idle or at least not involved in any transfers. After the substrates previously transferred from the fourth load lock 1826 have finished being processed in the second reactor 1824 , there is a transfer 1772 of processed substrates from the second reactor 1824 to the fourth load lock 1826 . This transfer 1772 is included in the concurrent transfer 1767 discussed above. Next, the fourth load lock 1826 performs a vent and/or cooling operation 1773 on the processed substrates recently received from the second reactor 1824 . Next, there is a transfer 1774 of the now cooled processed substrates from the fourth load lock 1826 to the fourth load and unload unit 1828 . Next, there is a transfer 1775 of unprocessed or preprocessed substrates from the fourth load and unload unit 1828 to the fourth load lock 1826 . The cycle then repeats (not shown).
[0048] From time zero on the timing diagram 1700 , there is a load and unload operation 1776 in the fourth load and unload unit 1828 , in which processed substrates are unloaded and unprocessed or preprocessed substrates are loaded in preparation for the next transfer towards the second reactor 1824 , i.e. a subsequent transfer from the fourth load and unload unit 1828 to the fourth load lock 1826 . The fourth load and unload unit 1828 is then idle or at least not involved in any transfers to or from the fourth load lock 1826 . Next, there is a transfer 1777 of processed substrates from the fourth load lock 1826 to the fourth load and unload unit 1828 . Next, there is an index operation 1778 . Next, there is a transfer 1779 of unprocessed or preprocessed substrates from the fourth load and unload unit 1828 to the fourth load lock 1826 . The cycle then repeats (not shown).
[0049] Operating efficiency and substrate processing throughput of the reactor-based system 100 and the reactor-based system 1800 can be compared with another reactor-based system (not shown) that includes a single reactor, only a single load lock and only a single load and unload unit. Such a single reactor, single load lock system would have the reactor idle while substrates are exchanged out of the single load lock. The reactor would further be idle as a result of the separate unloading of processed substrates from the reactor and loading of unprocessed or preprocessed substrates into the reactor. Comparison shows that embodiments of the reactor-based system 100 have a reduced cycle time of processing substrates and an increased throughput as compared to using only a single load lock with a reactor.
[0050] In the case where a processing duration as applied to substrates being processed in the reactor is greater than unload duration as applied to unloading substrates from load locks plus a load duration as applied to loading substrates into the load locks, each of the load locks has an idle time. Meanwhile, the idle time of the reactor is minimized or made zero. A capital expenditure of purchasing two load locks is thus offset by improved productivity as measured by substrate processing throughput, in that maximal use is made of reactor time.
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A substrate processing system having a hot reactor with two load locks and two associated load/unload units, and a related method of operating the system, are disclosed. Substrates are concurrently moved from the reactor into one of two load locks and from the other of the two load locks into the reactor. A bidirectional transfer mechanism is used for the concurrent transfers, such that successive transfers in opposite directions are interleaved. Substrates are heated in the load locks prior to processing in the reactor. The reactor applies processing to substrates, to form processed substrates. Processed substrates are cooled in the load locks after processing in the reactor. Respective load and unload units load substrates into the load locks and unload processed substrates from the load locks. The interleaved concurrent transfers minimize or make zero the idle time of the reactor.
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CROSS REFERENCE TO RELATED APPLICATIONS, IF ANY
The present application hereby claims the priority of provisional application Ser. No. 60/072,476 filed Jan. 26, 1998.
BACKGROUND OF THE INVENTION AND PRIOR ART
1. Field of the Invention
The present invention relates to the field of manufacture of golf club shafts, particularly of aluminum or aluminum alloys which must have a minimum defined stiffness and which benefit from weight reduction. As referred to herein, the term “defined stiffness” for golf shafts refers to a measured vertical deflection of the tip end of a shaft from which a weight is suspended when the butt or handle end of the shaft is clamped to horizontally support the shaft in cantilever fashion. The industry defined S, R, L, X stiffiess scale for golf shafts is well known. Defined stiffnesses of other sports articles are also known or are easily determinable.
2. Prior Art
Tubular sporting articles such as baseball bats and golf club shafts made of metal materials such as aluminum alloys which have a maximum modulus of elasticity of about 10.4 are well known. Throughout this disclosure, elastic (Young's) modulii expressed for example by the number 11 will be understood by persons skilled in the art to mean 11×10 6 psi.
As defined herein, the term metal matrix composite (MMC) refers to a metal or metal alloy having an undissolved portion of non-metal reinforcing fibers, platelets or particles uniformly dispersed therein. MMCs comprising alloys of metals such as aluminum reinforced with non-metal fibers or particles such as ceramic particles are known and, although their use has been broadly suggested for golf shafts, the usual reinforced aluminum alloys typically have elastic modulii significantly in excess of about 13 and may be formulated to have elastic modulii as high as 20 or 30 or even above pending upon the end use of the products for which they are intended. These MMC modulii are considered excessive and thus inherently unsuitable for golf shafts.
The elastic modulus of MMCs increases as the volume percent of reinforcing fibers such as carbon, silicon carbide or boron fibers or platelets or particles of ceramic, e.g., aluminum oxide, silicon carbide, etc. in the product increase from about 15% to 40% by volume. These MMC materials are of approximately the same density as or slightly higher density than non-reinforced alloys but are considerably stiffer, e.g., from 30 to 50 percent stiffer, than the same un-reinforced aluminum alloy. On the other hand, the tensile yield strength of aluminum alloy MMCs increases relatively insignificantly (less than 10%) over that of un-reinforced aluminum alloys despite the added non-metal reinforcement. Unlike alloying elements that dissolve in molten aluminum, the added reinforcing platelets, fibers or ceramic particles in MMCs remain in platelet, fiber or powder form with no significant chemical reaction. MMCs may therefore be generally categorized as continuous reinforced alloys or as discontinuous reinforced alloys. Continuous reinforced alloys employ strands or fibers for the reinforcement whereas discontinuously reinforced alloys use reinforcement in particulate or platelet form.
Continuously reinforced alloys or MMCs employing silicon carbide fibers have been suggested for use in tubular sports articles such as bicycle frame parts which require light weight and substantial stiffness. Continuously reinforced MMCs have not heretofore been found acceptable for commercial use in shaped articles such as golf club shafts further because of relatively poor workability characteristics of continuously reinforced MMCs. Mechanical workability is essential to obtain the desired shaft shapes without sacrifice of acceptable strength, flexibility, light weight and good fatigue resistance. MMC technology has generally emphasized the addition of substantial proportions of reinforcing fibers or powders to the matrix alloy to obtain substantially greater stiffness. This has resulted in MMCs which are inadequately drawable and thus unsuitable for formation of tubular shapes such as golf shafts which not only must have a tapered configuration with thin walls for light weight but must be reformed from the original tubular shape to form an enlarged cylindrical butt or handle end and a re-shaped short cylindrical tip end. Additional variations in the shaft wall thickness to create a kick point of maximum shaft flexibility at a desired position or to form the more recently introduced “bubble shaft” configurations having an enlarged section proximate the lower portion of the butt end of the shaft require additional steps in the forming process. Also, MMCs work harden relatively quickly which makes tapering of articles such as golf club shafts very difficult.
Various MMCs have been extensively studied but golf shafts manufactured therefrom for test purposes have previously proven unsuitable. U.S. Pat. No. 4,702,770 issued Oct. 27, 1987 to Pyzic, et al. is one example representative of boron carbide aluminum composite technology.
Accordingly, improved tubular shaped metal sporting articles having a defined stiffness and reduced weight due to a reduction in wall thickness, and with adequate strength despite this reduction in wall thickness are always desired. Shaped metal sporting articles such as golf shafts with high strength-to-weight ratios without sacrificing flexibility, torsional resistance or fatigue resistance and possessing workability properties required for economy of manufacture and ease of golf club assembly and repair are particularly desirable.
SUMMARY OF THE INVENTION
The present invention provides a golf shaft formed from a metal matrix composite material, said shaft comprising a handle portion, a tapered portion and a tip portion, the final dimensions of at least said tapered portion and said tip portion being re-formed from the starting dimensions of a tubular metal matrix composite material starting stock to provide a shaft with variations in wall thickness, said metal matrix composite comprising an aluminum alloy matrix having discontinuous reinforcement particles therein, and a minimum modulus of elasticity of 10.4 and a minimum yield strength and minimum modulus of elasticity related by the equation:
Y=71+6.84(E−10.4)
where Y is yield strength in KSI and E is modulus of elasticity in millions of pounds per square inch (MSI)—i.e. ×10 6 psi.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a table of material properties of various MMC's used for manufacture of golf shafts intended for use in iron type golf clubs.
FIG. 2 is a table of material properties of various MMC's used for manufacture of golf shafts intended for use in wood type golf clubs.
FIG. 3 is a golf shaft strength analysis graph made from the data of FIG. 1 plotting minimum strength vs. minimum modulus of elasticity of MMCs for shafts intended for use in iron type golf clubs.
FIG. 4 is a golf shaft strength analysis graph made from the data of FIG. 2 plotting minimum strength vs. minimum modulus of elasticity of MMCs for shafts intended for use in wood type golf clubs.
FIG. 5 is a cross section view of a typical golf club shaft.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIGS. 1 and 2 are tables respectively showing tip analyses for shafts intended for iron and wood type golf clubs displaying selected material properties of various MMC's which have been extensively examined for possible suitability for golf shaft manufacture. Note that the tip wall thickness of the iron shafts from FIG. 1 is thicker than the wall thickness for wood type shafts in FIG. 2 despite a smaller outside diameter for the tip end of the iron shafts. Although this is the ordinary relationship, in wood shafts designed with a smaller outside diameter at the tip, e.g., 0.312″, the tip wall thickness may be somewhat greater than for a corresponding iron shaft.
In each figure of drawings nine MMC formulations were compared with a base unreinforced 7001 aluminum alloy (# 1 in FIGS. 1 and 2 ). The desired minimum deflection and modulus of elasticity are known and the objective is to obtain the MMC formulations, if any, best suited to meet the design criteria and which possess adequate yield strength.
FIG. 3 shows a product design line drawn from the data of FIG. 1 determined by applicant to be minimum requirements golf shafts for iron type clubs showing tensile yield strength on the vertical axis expressed in kilopounds per square inch (ksi) and elastic modulus on the horizontal axis. The design objective is to reduce the weight of a golf shaft by reducing the wall thickness of the shaft while maintaining a required minimum deflection stiffniess to determine whether acceptable shafts can be manufactured through the use of one or more novel MMC formulations which must be mechanically workable to form the desired shaft configuration from a tubular stating stock. At the left side of FIG. 1, the shaded trapezoidal area represents, for comparison purposes, unreinforced aluminum alloys which have Young's modulii in the range of from 10-10.4 and maximum strength of about 110 ksi. Since the yield strength of an aluminum alloy MMC does not materially increase above that of the corresponding un-reinforced aluminum alloy, the optimum MMC design area is the shaded triangular area above the design line and to the right of the trapezoidal shaded alloy area. Instead of plotting strength on the vertical axis, those skilled in the art will understand that similar design line graphs can be constructed to illustrate the optimum design area for weight reduction or wall thickness reduction. As will be apparent, any reduction in wall thickness results in a corresponding reduction in shaft weight, strength and stiffness unless different material formulations are compared.
FIG. 4 is similar to FIG. 3 but shows the design area required for shafts intended for use in wood type golf clubs. It will be noted that the strength/modulus line is below that shown in FIG. 3 for shafts for iron type clubs. Shafts for woods are ordinarily designed to be weaker than shafts for irons because golfers more frequently hit the ground harder than intended with irons. Since the tip end of a golf shaft is subjected to the greatest stress concentration at the point where the shaft emerges from the head, this is where shaft failure most frequently occurs. Accordingly greater strength is required for shafts for iron type clubs.
FIG. 5 shows a horizontal cross-section of a typical golf shaft having wall thickness changes along the length of the shaft. The wall thickness at the handle end of the shaft is thinnest since the handle or butt end has the largest diameter. Conversely, the wall thickness at the tip end is largest. Transition points between the tip and the tapered portion of the shaft and between the butt and the tapered portion of the shaft are formed as the shaft is mechanically worked to its final shape from a tubular stating stock by well known metal manufacturing techniques. The shaft may also be formed with an enlarged bubble section proximate the juncture between the taper and the butt or with step tapering rather than continuous tapering or with any of a number of configurations depending only on the performance characteristics desired and the rules of golf. Accordingly, numerous metal formation steps may be required and the MMC formulation must be able to withstand the working steps.
Set forth below is a table showing the composition of MMC's having discontinuous silicon carbide (SiC) therein which were designed to have equal strength and stiffness as the Base alloy, but with progressively lighter weight and which are identified in FIGS. 1 and 2 as Nos. 2 - 9 , respectively. The Base is 7001 unreinforced aluminum alloy. The weight percentage of silicon carbide additive conforms to the formula SiC=4.166(E−10.4).
Base
#1
#2
#3
#4
#5
#6
#7
#8
#9
% SiC
0
2.5
5.0
6.6
8.7
10.8
15.0
19.2
23.3
E
10.4
11.0
11.6
12.0
12.5
13.0
14.0
15.0
16.0
Testing and Analysis
One batch of golf shafts for test purposes was formed from an MMC comprised of a commercially available 7071 aluminum matrix incorporating 12% silicon carbide particulate reinforcement and an elastic modulus of 15 . This MMC had a density of 0.103 lbs/in3. MMC tubes having an outside diameter of 0.600 and a wall thickness of about 0.020″ were first tapered in a two step process and test samples having a wall thickness of about 0.025″ were successfully tapered in a one step process to form golf club shafts; however, an unacceptable number of the resulting shafts were found to exhibit micro-cracks in the tip end and, when straightened in an auto-straightener, the brittle shafts experienced frequent breakage and were thus unsuitable for mass production.
Other commercially available MMCs were studied but none was believed to possess the characteristics required for manufacture of golf shafts. It was then considered that testing of MMCs having a significantly lower proportion of reinforcing composite than is ordinarily available from commercial suppliers of MMC stock should be studied since one or more of them might prove beneficial for golf shaft manufacture. An MMC was then specially formulated according to applicant's specification comprising 7090 aluminum alloy reinforced with 2.5 w % boron carbide particles. This MMC, when tested, had a density of 0.099 lbs/in3 and a Young's modulus of 11.5 and thus appeared to meet the golf shaft design criteria.
The above test results led applicant to conclude that continuously reinforced alloys, namely those with fiber rather than particulate or platelet reinforcement were unacceptable but that a discontinuously reinforced alloy, i.e. one with particulate or platelet reinforcing or with very short length fibers which essentially act like particle reinforcement might prove acceptable for golf shaft manufacture. Particles having an aspect ratio of up to 3:1 are considered acceptable and are considered discontinuous.
Further testing and experience gained from unsuccessful test results led to the determination that discontinuously reinforced 7000 Series aluminum alloy MMCs, particularly 70XX alloy MMCs, can be successfully employed for the manufacture of shaped tubular sporting articles by ensuring that the starting blank of MMC tubular stock possesses a modulus of elasticity in the range of about 10.6-12.5, a percentage elongation of at least 4% for adequate workability, adequate strength and a hardness which does not materially damage cutting and shaping tools. Applicant has also concluded that particle shape, rather than particle composition, has a more significant abrasive effect which rapidly damages cutting and shaping tools. Fine particles, rather than fibers or platelets have been found to be less detrimental to cutting and shaping tools. The required properties of an MMC which meets the design criteria falling within the shaded triangular areas of FIGS. 3 and 4 are likely possessed by a number of different MMCs comprised of a metal matrix of various alloys of aluminum and discontinuous non-metal ceramic reinforcement particles in weight percentages preferably in the range of from about 1-8% and not exceeding about 10%. Without limitation, such MMCs may comprise alloy matrices of 7049, 7050, 7075, 7178 and 7475 aluminum. Golf shafts comprised of such MMCs can be reliably and economically produced.
At the time of this disclosure, the presently preferred MMC for production of golf shafts is produced from an aluminum alloy containing about 11% zinc which is available from PEAK Company of Germany. The MMC contains 5% loading of spherical silicon carbide particles and has a Young's modulus of 11.5. Tubular metal matrix composite material stock formed by a spray casting process is presently preferred.
SUMMARY
Various methods for forming tapered metal golf club shafts are well known and need not be modified for forming MMC shafts. A starting stock aluminum alloy tube having larger diameter and wall thickness than the final shaft size is first drawn to form the butt end of the shaft with an outside diameter of about 0.600″ to receive a wound or slip on grip. Then, the remainder of the shaft is tapered and tip end of the shaft which receives the clubhead may remain tapered or then be formed to a cylindrical configuration. A cylindrical tip section of the finished shaft will typically have an outside diameter of from about 0.335″-0.400″. The wall thickness of the shaft may also be varied along the length of the shaft. As is known, golf shafts are drawn by inserting a mandrel through one end of the tubular starting stock and pulling through a die to cause the wall thickness of the tube to be reduced. The tapering may be accomplished by one of a variety of methods including hammering or swaging; step sinking; roto-drawing through a tube reducer; or by various combinations of these methods. Variations of shaft wall thickness are shown along the length of the shaft.
Persons skilled in the art will appreciate that various modifications of the preferred embodiment may be made without departing from the teachings herein and that the scope of protection is defined by the claims which follow. For example, golf shafts formed from other aluminum alloy bases reinforced with discontinuous non-metal particles or platelets other than SiC may be fabricated so long as the minimum yiels strength and modulus of elasticity are related as described and claimed.
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Formed tubular sporting articles subjected to repeated flexure such as golf club shafts are made from metal matrix composite materials (MMCs) in which a metal alloy matrix is discontinuously reinforced with undissolved particles or platelets in proportions to result in an article having a variable wall thickness, and a minimum modulus of elasticity of 10.4 and a minimum yield strength and minimum modulus of elasticity related by the equation:
Y=71+6.84(E−10.4)
where Y is yield strength in KSI and E is modulus of elasticity in units×10 6 psi. The sporting articles are lighter than conventional and have a modulus of elasticity substantially less than that of ordinary MMCs.
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CROSS REFERENCE TO RELATED APPLICATIONS
[0001] N/A
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] N/A
BACKGROUND OF THE INVENTION
[0003] This invention relates generally to a method of assembling a semiconductor chip electrically and mechanically connected to a substrate, particularly in a flip chip configuration.
[0004] Assembly of solder bumped chips such as flip chip or chip scale package (SCP) is an emerging technology which satisfies the demands of the ever-increasing requirements for high I/O density, small form factor, and improved performance in integrated circuit (IC) design. In the process of chip assembly, a chip is mounted on a substrate with any kind of interconnect material. Among the many kinds of interconnect materials, solder has remained a predominant choice. Solder bumped chip assembly consists two major steps: (1) chip soldering and (2) underfill encapsulation. To attach chip to the substrate, a flux is applied to the substrate or solder bumps on the chip. The chip is then aligned with the bond pads on the substrate, placed, and reflowed, forming electrical connections and mechanical joints between flip chip and substrate. After soldering a solvent cleaning step is usually involved to remove the flux residue which otherwise weakens the underfill adhesion which in turn degrades solder joint reliability. The cleaning process is a difficult operation, often costly and time consuming, involving solvents and expensive equipments. Therefore, there is a need to develop a new technology that does not require this cleaning process.
[0005] Another issue in the implementation of solder bumped chip technology when applied to organic polymer substrate is the mismatch of the coefficient of thermal expansion (CTE) of the chip, and that of the substrate having a higher CTE. The build up stress on solder joints upon thermal excursions experienced during the application of the device causes solder joint fatigue and leads to the failure of the interconnect joints. To minimize this problem, an underfill material is applied in the interspace of chip and substrate after chip soldering to assure the reliability and electric integrity. The traditional underfill material is typically a highly flowable liquid formulation, containing filler particles to reduce CTE. The underfill material is dispensed along the edges of the chip and allowed to wick into the space between the substate and the chip. The capillary action allows the underfill to flow out to the opposite sides of the chip and completely fill the gap between the chip and the substrate. Even though the substrate is usually heated to an elevated temperature to facilitate the underfill flow, the process still takes more than seconds to completely underfill the chip, which is considered a bottle neck in manufacturing process. After underfilling, the package is subjected to an elevated temperature for underfill curing. The cured underfill material redirects or redistributes the stress away from tiny solder joints, thus enhancing the package reliability. In addition, underfill materials also serve as mechanical and environmental protection, which increases the resistance to shock, vibration, moisture, solvent, and provide thermal dissipation between chip and substrate.
[0006] While traditional capillary flow underfill materials with reduced flow and cure time are dominant in current underfill applications, the use of so-called pre-deposit fluxing underfill offers an attractive alternative which would speed up package processing and enhance compatibility with surface mount technology (SMT). In addition to bearing the functions provided by traditional underfill encapsulant, the pre-deposit underfill materials are integrated with fluxing capability. The overall assembly process based on this type of underfill material is simplified by combining three basic steps: (1) underfill dispensing, (2) chip placement, and (3) reflow. During reflow, the fluxing agent incorporated in underfill materials provides sufficient activity to remove surface oxide on solder bumps and bond pads, forming interconnect joints. In the meantime, the underfill material is chemically crosslinked, forming a strong network structure providing mechanical and environmental protection as described for traditional underfill encapsulation. The benefits of the pre-deposit underfill process are well explored in the recent years. These include simpler process to control, higher throughput, self-fluxing action, etc. Even though there has been an explosion of interest and great effort to develop this technology throughout the past decade, the use of pre-deposit underfill is, however, not without its inherent problems and limitations. One of the obstacles which pre-deposited fluxing underfill materials must overcome, is placement of the component without void entrapment. A direct consequence of underfill pre-deposit followed by fast paced chip placement (less then a second), is that the underfill material is forced to flow toward the periphery of the chip in such a short time that air is entrapped around solder bumps (FIG. 2). These air bubbles will generate internal vapor pressure when the temperature increases during reflow, leading to process failures such as chip float and misalignment of solder bumps relative to the matching bond pads. Furthermore, the trapped air bubbles around solder joints pose a great threat to the solder joint performance, defects such as irregularity, solder extrusion, incomplete wetting, voids inside joint are often encountered. Yet, another challenge of developing such pre-deposit fluxing underfill materials is the interference of inorganic filler particles on soldering during reflow as solid filler particles will inhibit the solder wetting on bonding pads. How to incorporate fillers into pre-deposit fluxing underfill to reduce CTE and apply such pre-deposit underfill in manufacture processing remains uncertain. As a result, the pre-deposit underfill typically contains no filler, thus has a CTE much higher than that of capillary flow underfill and therefore unparallel performance.
[0007] It would be desirable to develop a method that takes advantages of capillary flow underfill process, such as void free, low CTE, widely accepted industry processing practice, and combines the attractive features of fluxing underfill such as shorter manufacturing cycle, no cleaning step required, underfill cured in the same step as solder reflow, and SMT processing compatibility. Such a processing method should yield overall higher efficiency, and low cost without compromising the reliability and performance.
BRIEF SUMMARY OF THE INVENTION
[0008] The present invention provides a method of assembling a substrate and an IC die in a flip chip configuration using a tacky thermosettable flux and underfilling such a device. According to the present invention, as described in the illustrated embodiments, a thin layer of tacky flux is applied to the substrate or preferably to the solder bumps, a chip is placed on the substrate with the solder bumps in contact with the matching bonding pads. The tacky flux provides temporary adhesive bonding to immobilize the chip. An underfill is then dispensed along the edges of the chip and the whole package is transferred to reflow process. During solder reflow process, three major processing tasks are accomplished in one single step: (1) the underfill flows into the gap between chip and substrate and completely fills the interspace, (2) the tacky flux activates the bonding surface and facilitates solder reflow and joint formation, (3) underfill curing. Because tacky flux is formulated to be compatible with underfill, it is chemically incorporated into the cured underfill network structure.
[0009] In one aspect of present invention there is provided an integrated method of underfilling a device on a substrate during reflow process. The method comprises applying tacky flux to solder bumps or substrate to be joined and placing the chip on substrate so that the chip is temporarily held in place. The underfill is deposited on the substrate along the edges of the chip and the whole device is subjected to a reflow process. In general, a reflow process can be roughly divided into four major stages: heating stage, soaking stage, and the reflow and cooling stage. The viscosity of underfill material is reduced as the temperature of the whole device is gradually increased in the heating stage, this will facilitate the underfill to flow into the gap, as a result, the gap is completely filled with underfill material before the temperature reaches the solder melting point. Because the underfill is allowed to flow, via capillary action, into the gap between chip and substrate, the underfill material is able to wet any surface in contact and replace the air space underneath the die with underfill material, avoiding the formation of air bubbles. The incorporation of underfilling into the solder reflow process removes the typical bottleneck of the manufacturing process, thus significantly shortening the manufacturing cycle.
[0010] Another aspect of the present invention is increased gap height during the underfilling process. Because the device is underfilled before reflow and solder collapse, the maximum clearance between chip and substrate for the underfill process is increased. The size of the gap is controlled by the height of solder bumps and typically varies from 3 to 30 mils. With the increase of I/O density in IC devices, the solder bumps (i.e., the clearance between the chip and the substrate) are becoming even smaller. This reduced height presents a greater challenge for the underfill, making capillary flow more difficult and increasing the time needed to fill the gap. Typically, depending on the pad design and layout, there is a 15-30% drop in the clearance after solder reflow in C4 (controlled collapse chip connection) process, this clearance drop further increases the chance of introducing underfill defects such as voids, filler segregation, and increased flow time. Underfilling before soldering provides the maximum clearance for the underfilling process.
[0011] In another aspect of present invention, a uniform fillet is formed after solder reflow. Traditional process of chip bonding first followed by underfill dispensing tends to create a non-uniform fillet around the chip. Typically, the fillet will be large enough on the one or two sides of chip where the underfill is originally dispensed and there is not enough underfill material flowing out to the other sides of the chip to form a desirable fillet profile. An additional dispensing operation is usually required to compensate the material deficiency on the other sides, which also brings in additional manufacturing time. Underfilling before solder collapse assures the formation of uniform fillet. Upon solder collapse, the chip will force the additional underfill material to flow out to the edges of the chip, providing enough material to form a desirable fillet.
[0012] In another aspect of present invention, a tacky flux is provided to block the interference of filler particles on the solder joint formation. The current process of pre-deposit fluxing underfill does not allow the use of underfill material with a high percentage of filler to achieve a sufficiently low CTE, usually around 25-45 ppm/° C. Use of high percentage of filler content inhibits solder wetting on bond pads, thus preventing the formation of a desirable solder joint. This is why current formulations of this type of pre-deposit fluxing underfill usually contain no or very low percentages of fillers. The resulted high CTE of the material limits the performance of the final package. The process of the present invention takes advantage of tacky flux to prevent the interference of filler during solder reflow, with the tacky flux forming a thin layer adhering to the contacting bump and pad, and acting as a physical barrier to the filler intrusion. A 100% interconnect yield can be achieved reproducibly.
BRIEF DESCRIPTION OF THE FIGURES
[0013] [0013]FIG. 1 is a process flow chart illustrating the steps for assembling a chip and substrate in accordance with conventional capillary flow underfill process.
[0014] [0014]FIG. 2 is a process flow chart illustrating the steps for assembling a chip and substrate in accordance with pre-deposit fluxing underfill process.
[0015] [0015]FIG. 3 is the comparison of entrapped voids after chip placement on glass substrate using different process: (A) pre-deposit underfill process, (B) pre-deposit underfill process after cure, and (C) the present integrated process. Flip Chip Technology FA10-200 on glass substrate with 5 mil bump diameter and 10 mil pitch is used for this illustration.
[0016] [0016]FIG. 4 is a process flow chart illustrating the steps for assembling a chip and in accordance with present invention-option 1.
[0017] [0017]FIG. 5 is the x-ray images of assembled Flip Chip FB250 with organic surface protection (OSP) coating on pads using the process in accordance with the present invention-option 1. Indium tacky epoxy flux PK-X003 and underfill UF-X10 containing 20% filler (A) and 40% filler (B) is used for this illustration.
[0018] [0018]FIG. 6 is a process flow chart illustrating the steps for assembling a chip and substrate in accordance with present invention-option 2.
[0019] [0019]FIG. 7 shows the integration of underfill, curing and solder bump reflow into one reflow step. The underfilling process can be completed in a reflow oven or before the package is sent into a reflow oven. Also shown is the typical reflow profile described in four stages: (1) heating stage, (2) soaking stage, (3) reflow and (4) cooling stage.
DETAILED DESCRIPTION OF THE INVENTION
[0020] A new integrated void free process for assembling solder bumped chips such as flip chip or chip scale packages (CSP) using a tacky thermosettable flux is provided. The tacky flux is not only sufficiently tacky to keep the chip attached to the substrate while other processing (e.g., addition of the underfill) takes place, but also fully compatible with underfill and will not cause delamination. The traditional tacky fluxes were generally incompatible with underfills and caused delamination of the underfills. They were used with “regular” soldering, processes in which underfills were not used. These traditional products contained much resin (which added the stickiness to the product), along with solvent and activator.
[0021] By tacky thermosettable flux, we mean a flux which is flowable before reflow, provides good flux properties (e.g., removal of oxides, etc.), and, after reflow, is cross-linked to form a thermosetting polymer. Examples of tacky thermosettable flux include epoxy fluxes, polyimide fluxes, polyacrylate fluxes, polyurethane fluxes, and combinations thereof. Other polymers that perform similarly also can be used, either individually or in combination with other such fluxes.
[0022] Furthermore, the area of prime interest herein is the new process that results from use of the new tacky thermosettable flux. As indicated in more detail below, the new process allows the combination of several steps that were previous conducted separately, thus simplifying the underfilling, reflow and curing steps. Furthermore, the resulting IC has a much lower failure rate, due to the absence of underfill voids in the new process. It should be noted that, although several tacky fluxes are disclosed herein, the new process is not confined to the use of those fluxes. Instead, any flux that is sufficiently sticky to hold the chip to the substrate during the steps discussed can be used in the new process. (I.e., the flux must be sufficiently sticky to prevent the component from floating away.)
[0023] The tacky flux is first applied to the solder bumps or substrate using conventional methods followed by placement of the chip onto the substrate so that the solder bumps are in contact with the substrate bond pads. The underfill is then dispensed along the edges of the chip and the device is transferred to a reflow cycle. During the reflow heating, the underfill material flows into the space between chip and substrate, driven by capillary action, leaving no entrapped voids in the underfill. In the meantime, the device is reflowed and cured. The tacky epoxy flux is designed to provide temporary adhesion between the electronic components and substrate as well as provide fluxing activity for soldering during reflow. The tacky flux can be composed of one or more fluxing agents and a combination of epoxy (or other fluxes listed above), hardener, and/or curing agent. The tacky epoxy flux is formulated to have similar chemical nature as epoxy based underfill materials and thereby will be incorporated into the final polymer network structure through diffusion and chemical reaction after reflow, without deterioration of the underfill performance. The tackiness is provided by the high molecular weight epoxy, hardener, or the combination of the two. The new process consolidates underfilling, solder reflow, and underfill curing into a one-step reflow process, thereby simplifying the flip chip packaging process which otherwise requires separate solder reflow and underfilling steps. The new process combines the advantages of conventional void free capillary flow underfill process and simple pre-deposit fluxing underfill process, and therefore optimizes the manufacturing process without compromising any performance requirements. The tacky flux will prevent the chip from floating, which will cause misalignment between bond pad and solder bumps. The sequence of underfilling before solder reflow facilitates underfill flow because of the increased clearance between the chip and substrate created by the unreflowed solder bumps.
[0024] [0024]FIG. 1 illustrates the typical process of assembling a chip and a substrate or chip carrier by conventional capillary flow underfilling. The substrate ( 101 ) typically comprises silicon, ceramic, glass, FR-4, BCB, polyimide, or combination thereof, and is fabricated as printed circuit board (PCB) or chip carrier used in flip-chip technology. The substrate has coplanar metallurgical bond pads ( 102 ). The flux is applied to the substrate as a thin film ( 103 ) using various flux application methods such as spray, brushing, pin transferring and printing. Alternatively, the flux can be applied to the solder bumps attached to the flip chip by dipping the solder bumps into a thin layer of flux on a motorized flux tray (not shown). The bumps can be Pb-based or Pb-free solder alloys. A chip ( 104 ) is shown mounted on a substrate ( 101 ) with solder bumps ( 105 ) connected to the chip aligned with the bond pads ( 102 ) of the substrate ( 101 ). During reflow, the flux ( 103 ) removes the oxide on the surface of solder bumps ( 105 ) attached to the chip ( 104 ) and the oxide on the bond pads ( 102 ) on the substrate ( 101 ), a mechanical and electrical solder joint ( 106 ) is thus formed between chip ( 104 ) and substrate ( 101 ). The chip/substrate combination is cleaned to remove the flux residue ( 107 ) which otherwise, will hinder the underfill flow and degrade the adhesion of underfill to the substrate, chip and solder joints. An underfill material ( 108 ) is dispensed through a needle ( 109 ) and deposited along the edges of bonded chip using predetermined patterns such as one-side, L type pattern, double L pass, or L pass followed by another L pass on the opposite sides. The underfill material ( 108 ) is allowed to wick into the gap formed between bottom side of the chip and the top of the substrate by capillary action. The underfill flow process is usually facilitated by heating the substrate to a temperature T2, which is dependent upon the flux used and is described in more detail later herein. Generally, the temperature is between approximately 20 and 130° C. The flow process can be completed in a matter of seconds depending on chip size, clearance between chip and substrate, I/O density, and the selected underfill material. As the result of capillary flow, the underfill material is able to replace any air in the interspace between chip and substrate. After underfilling, the whole device is subjected to a high temperature curing process which can be varied from few minutes to few hours. A mechanically strong and stable adhesive layer ( 110 ) is formed between chip and substrate, providing stress relief and environmental protection to the package.
[0025] While conventional capillary flow underfills now possess improved flow speed and cure rate, they still require a few more processing steps beyond the typical SMT process which typically consists of solder paste or flux deposition, component placement, and reflow soldering. In recent years, pre-deposit fluxing underfill materials have been extensively explored in order to meet the demand of low cost, high throughput, and SMT compatibility. The overall manufacturing process is simplified significantly as illustrated in FIG. 2. The underfill material ( 201 ) is deposited, in a desired pattern, onto the substrate ( 202 ), which has been baked beforehand to release any surface moisture. A solder bumped chip ( 203 ) is mounted onto the substrate with solder bumps ( 204 ) aligned to the corresponding bond pads of the substrate ( 205 ) in a one-to-one fashion. During the same reflow process as used for reflowing solder paste, the underfill material ( 206 ) provides the fluxing capability to assist the formation of solder joint ( 208 ) and undergoes a curing reaction to form a protective underfill layer ( 209 ). Although extensive effort has been made to promote this technology, many problems still exist as this moves into real world of applications. One of the inherent problems is the void entrapped during chip placement. This is because the underfill material ( 206 ) is unable to fully wet the surface and expel the air out of the space between chip and substrate before fast paced chip placement (typically less than one second) is completed. A confined air bubble ( 207 ) is formed around the corner of each individual solder bump, mostly behind solder bumps along the underfill flow direction. This situation becomes more significant when a fully populated area array solder bumped chip is used as demonstrated in FIG. 3(A). These air bubbles, with diameters about one-third to half the diameter of solder balls, pose a great threat to the integrity of solder joint reliability. Solder joint failure such as solder extrusion, and joint cracking has been reported due to the presence of these voids ( 210 ) in the cured underfill. The situation can be worsened when these air bubbles expand and/or merge to form bigger bubbles (FIG. 3(B)), thus causing a greater chance of chip floating or solder joint failure.
[0026] The present invention provides an integrated solution to the problems associated with the prior art and takes advantages of capillary flow void free underfilling and a simplified manufacturing process. These advantages will be made clear in the following detailed description and accompanying drawings of the present invention.
[0027] Illustrated in FIG. 4 is representative of the processes for assembling a chip in accordance with the present invention. The process begins with the application of tacky epoxy flux ( 403 ) on either substrate ( 407 ) or solder bumps ( 402 ) attached to a chip ( 401 ). There are several methods available for applying tacky flux to a substrate or solder bumps. For examples, brushing, printing, spraying, roller coating, pin transferring, or dispensing are well known techniques used in this field. Another method, often called flux dipping, involves the use of rotary drum having a doctor blade to control the flux thickness. The rotary drum has a temperature controller, providing a proper viscosity, to enable a high volume manufacturing process. These rotary drum flux applicators are readily available from pick and place machine vendors. The tacky epoxy flux has sufficient chemical activity to activate solder bumps to form reliable solder joints with bond pads, sufficient tacky force to adhere the substrate and pre-aligned chip during underfilling, and a proper viscosity to enable high volume manufacturing process. The tacky epoxy flux is typically composed of one or more fluxing agents, and a combination of tacky epoxy, hardener, and/or curing agent. (As indicated above, other types of fluxes, such as polyimide fluxes, can also be utilized.) The tacky flux is formulated with compositions compatible with or similar to underfill composition and therefore will be incorporated into the adhesive network structure after reflow heating cycle. In this context the word compatible means that the tacky fluxs are composed of chemicals which are reactive to the epoxy or other compositions in underfill material. During reflow heating, the tacky flux is solublized in the underfill material and become a part of the net work structure after curing.
[0028] Examples of tacky fluxes include PK-001 and PK-002, products sold by Indium Corporation of America. One example of a tacky epoxy flux that can be applied at an ambient temperature is PK-X003 manufactured by Indium Corporation of America, the room temperature Brookfield viscosity of this material is around 50000 cps. However, it should be emphasized that other tacky fluxes can also be used.
[0029] One example of an underfill that can be used along with this epoxy flux is UF-X10, also manufactured by Indium Corporation of America. The Brookfield viscosity of this underfill is around 3000 cps at room temperature. Note that the underfill can contain additional flux to further improve the efficiency of the reflow process.
[0030] The flux is based on epoxy chemistry, for example, in order to be compatible with epoxy based underfill (if epoxy underfill is the type used). The flux often appears to be brownish tacky paste and can be applied at 25° C. using various method such as dipping, printing or pin-transferring.
[0031] Alternatively, the tacky epoxy flux can be moderately heated to achieve a proper viscosity for the flux application. In case of dipping fluxing, the pick and place arm ( 404 ) picks the chip ( 401 ) and dips the solder bumps ( 402 ) into a thin flux film on the rotary drum which has been preset at a temperature T 1 , depending on nature of flux For example, T 1 for PK-001 (an epoxy flux) is approximately 40-70 C. A sufficient amount of tacky flux ( 403 ) is picked up and transferred on the surface of solder bumps facing toward the substrate. The chip ( 401 ) is mounted onto the substrate ( 407 ) with the individual bumps ( 402 ) in contact with corresponding bonding pads ( 405 ). A thin layer of tacky flux ( 406 ) temporary holds the solder bumps ( 402 ) and bonding pads ( 405 ) together and prevents the chip ( 401 ) from shifting during the next process.
[0032] Underfill ( 408 ) is deposited along the edges of the chip in the desired pattern using a dispensing needle ( 409 ) attached to a dispensing machine. The whole device is then subjected to a heating cycle as commonly used for solder paste reflow. During this heating cycle, three major tasks are accomplished: (1) during the heating stage, the underfill material ( 408 ) flows into the gap between chip ( 401 ) and substrate ( 407 ) by capillary force and completely replaces the air in the gap prior to the solder melting, therefore leaving no air bubbles in the underfill (FIG. 3(C)), and the tacky epoxy flux ( 406 ) provides enough tack force to hold the component in place, (2) the tacky flux and fluxing component in underfill material activate the solder bump and bond pad surface on the substrate facilitating the formation of the new solder joints ( 410 ), (3) the underfill material completes curing to form a strong adhesive layer ( 411 ), thus providing mechanical, electrical, and environmental protection for the electronic device. Since the tacky flux ( 406 ) is compatible with the epoxy underfill ( 408 ), it will completely merge and react with the underfill matrix at the elevated temperature and become part of the network structure after curing, and therefore does not adversely affect the solder joints. The overall process can be simplified as:
[0033] 1. Dip fluxing at T 1 .
[0034] 2. Place chip ( 401 ) on substrate ( 407 ) at T 2 , where the temperature T 2 is not too high so that the tacky thermosettable flux ( 406 ) will provide sufficient adhesion to hold the chip ( 401 ) in place during underfilling; the tacky epoxy flux ( 406 ) also provides a physical barrier against filler penetration into the bonding area of solder bumps ( 402 ) and bond pads ( 405 ). The temperature T2 is dependent upon the type of tacky thermosettable flux chosen. For example, T2 for PK-X003 has a T2 of approximately 30-120 C, while PK-002 has a T2 of approximately 20-100 C.
[0035] 3. Underfilling, reflow soldering and underfill curing in one single reflow heating cycle. This process can be conducted in, for example, a forced air convection oven, such as a BTU VIP 70 , using a defined curing profile (e.g., ramping up linearly from room temperature to 220° C. at a ramp rate of 1° C./sec, then cooling down at a ramp rate of 2° C./sec. FIG. 7 shows an example of such a heating profile.) The tacky epoxy flux ( 406 ) will also be cured and incorporated within underfill matrix.
[0036] As an example, Flip Chip FB250 daisy chain chip was assembled using Indium tacky epoxy flux PK-X003 and Indium underfill UF-X10, 100% solder joint yield was obtained reproducibly using this process (FIG. 5(A) and (B)). FIG. 5A shows an x-ray of the completed Flip Chip using 20% filler (e.g., silica), while the chip in FIG. 5B used 40% of the filler. By comparing these 2 x-rays, we can tell that the variation in filler had no impact on the new process described herein. (I.e., the figures are similar.)
[0037] Alternatively ( 2 ), the underfilling process may be completed prior to the reflow processing as illustrated in FIG. 6. Instead of sending the device into reflow oven for the completion of underfilling, the underfill material is allowed to completely fill the gap and flow out to the edges of the chip before entering reflow process. (Note that the term “soaking” is frequently used to describe that part of the process that takes place when the product is in the oven, when the temperature is kept nearly constant, in order to allow the underfill to flow under the chip and not begin the curing process. See, for example, Stage 2 in FIG. 7.) This is especially useful when a large chip is to be underfilled as more underfill material is needed to fill the gap. Compared with option (1), the first two steps of option (2), fluxing and placement are the same as option (1) as described in FIG. 4. Following chip placement, regular underfill dispensing pattern such as one side pass, one side pass followed by another one side pass, L-type (i.e., 2 adjacent sides) pass or L-type pass followed by another L-type pass when underfill ( 601 ) flows out to the opposite side of the die is applied, the preferred dispensing pattern is selected to offer best chance to have no or minimal voids in a shortest underfilling time and create ideal fillet geometry. The substrate ( 602 ) may be heated to an elevated temperature T 2 to assist underfill ( 601 ) flow as commonly used for capillary flow underfill processing. The tacky epoxy flux ( 603 ) provides sufficient adhesion to hold the chip ( 604 ) in alignment with the substrate ( 602 ) during underfilling, preventing the chip ( 604 ) from floating and shifting. The tacky epoxy flux ( 603 ) also serves as a protective layer to prevent the filler of the underfill from interfering with solder joint formation. After this separate underfillng step, the device is subjected to a standard reflow process as used for the process of pre-deposit underfilling to establish interconnected solder joints ( 605 ) and form a desirable underfill layer ( 606 ). Compared to the capillary flow underfill processing, the present invention requires no separate fluxing and bonding processes, and flux residue cleaning step is also eliminated. The whole assembly process for Option 2 has been summarized as:
[0038] 1. Dipping fluxing at T 1 .
[0039] 2. Place chip on substrate at T 2 , where the temperature T 2 is not too high so that the tacky epoxy flux maintains sufficient bonding strength between the chip and substrate to prevent any misalignment during underfilling.
[0040] 3. Dispensing and capillary flow underfilling as used for conventional capillary flow underfill.
[0041] 4. Reflow and cure.
[0042] It is easy to understand that the process involves no placement void issue as encountered in pre-deposit underfill processing. Some other assisting measures used for capillary flow underfilling as demonstrated in existing processes are also suitable for the present invention, such as: 1. Providing a hole in the middle of substrate and allowing the underfill material to flow towards the center from entire perimeter, 2. Using dams to guide the underfill flow and apply a vacuum source to draw underfill material from one open end of the dam to the opening at the opposite end.
[0043] Application of the present invention does not restrict the means in which the tacky flux is applied. Other conventional methods such as printing, pin-transferring, dispensing, are equally applicable. Likewise, the surface to which the flux is deposited is also variable. The tacky flux can be placed on the solder bump surface facing toward the substrate or on substrate bond pads or other active surface for bonding. One way of assembling a chip is to pin transfer the tacky flux onto the bond pads of substrate, place the chip, underfill and reflow the package.
[0044] Thus it is apparent that the present invention provides an integrated processing method of assembling a solder bumped chip device that combines the advantage of void free capillary flow underfilling and integrated solder reflow and underfill cure process as further illustrated in FIG. 7. While the invention has been described and illustrated with reference to the preferred embodiments, it is not intended to restrict or in any way limit the scope of the present invention. It is common to those skilled in the art to have additional modifications, variations, substitutions and equivalents in practicing the invention without departing from the spirit of current invention as defined by the appended claims.
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An integrated void-free process has been developed for attaching a solder bumped chip to a substrate. The chip is first dipped in a tacky thermosettable flux, and the chip is mounted on the substrate. An underfill is dispensed along the edge of the chip The device is then sent into the reflow furnace to complete the underfilling (which optionally can be completed before reflow), solder reflowing and underfill curing. The flux also acts as a physical barrier minimizing, if not eliminating, the interference of filler on solder wetting and resulting metallurgical joints formed between the solder and the bond pads. The process allows for the integration of a void free conventional capillary flow underfilling process and a pre-deposited fluxing underfilling process by using a tacky thermosettable flux, avoiding the problems associated with each of the individual processes and requiring less time for the overall process.
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CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation of U.S. Ser. No. 13/019,297, filed Feb. 1, 2011, incorporated by reference herein in its entirety, which is a divisional of U.S. Ser. No. 10/540,539, filed Oct. 4, 2006, now U.S. Pat. No. 7,910,711, which is a national stage of PCT/CN2003/01109, filed Dec. 24, 2003, which claims the priority benefit of Chinese Application No. 02158110.X, filed Dec. 24, 2002, and Chinese Application No. 03109786.3, filed Apr. 21, 2003.
SEQUENCE LISTING
The following application contains a sequence listing in computer readable format (CRF), submitted as a text file in ASCII format entitled “SequenceListing,” created on May 3, 2016, as 22 KB. The content of the CRF is hereby incorporated by reference.
FIELD OF THE INVENTION
The present invention relates to a human cancer-related gene, its encoded products and their applications in genetic engineering and protein engineering areas, as well as in medical diagnosis and treatment.
BACKGROUND OF THE INVENTION
Cancer is the major health problem threatening human lives. Hepatocellular carcinoma (HCC) is one of the most serious among cancer diseases. It is reported that the new cases of primary hepatocellular carcinoma exceeds over one million worldwide each year. 70% of the new cases occur in Asia, and about 40-45% of the worldwide new cases occur in China. The total number of new hepatocellular carcinoma cases every year in China is about 450,000, and the number is increasing, especially in those between ages 20-60. The high incidence, difficulty in early diagnosis, fast growing rate, high reoccurrence, and the high mortality rate make HCC a most malignant cancer. Most HCC patients have already progressed to the intermediate stage or late stage when diagnosed, and they can only survive for 3-6 months if without a proper treatment.
To elucidate the mechanism underlying cancerogenesis would help for cancer prevention, diagnosis and treatment. Early diagnosis is crucial for raising the curative rate and reducing the mortality. Currently used HCC-diagnostic marker, the serum AFP, has 30% of negative results in HCC patients, while some benign liver disease can cause a significant increase of AFP level in serum, creating some difficulty in differential diagnosis. It has been found that the hepatocarcinogenesis is related to individual hereditary susceptibility. Individuals with different genetic backgrounds possess different handling capability toward environmental carcinogens. This leads to different risk of suffering from cancer for individuals. It is the various genotypes and the genetic diversity that cause the different genetic susceptibility for cancerogenesis.
Cancer is essentially a cellular hereditary disease. Although a great number of cancer-related genes have been discovered, the mechanisms of the cancerogenesis and the development remain to be elucidated. The known oncogenes can be divided into five categories according to the cellular localization and function of their encoded proteins: I. genes that encode growth factors, including sis, int-2, hst, fgf-5; II. genes that encode growth factor receptors, including erbB, erbB-2, fins, met, ros, and others; III. genes that encode signal transduction molecules in cytoplasm, including abl, src, ras, raf, yes, fgr, fes, lck, mos, and others; IV. genes that encode regulatory molecules for cell proliferation and apoptosis, including bcl-1, bcl-2 and others; and V. genes that encode the nuclear DNA-binding proteins (transcription factors), such as myc, myb, fos, jun, B-lym, ski, ets, rel and others. It has been demonstrated that ras, src, myc, met and p53 etc. are the genes closely associated with HCC.
SUMMARY OF THE INVENTION
This invention provides a novel human cancer-related gene and its encoded products.
This novel human cancer-related gene provided by this invention is designated as LAPTM4B. It comprises one of the following nucleotide sequences:
1. The human cancer-related gene comprises one of the following nucleotide sequences:
1). SEQ ID No: 1, SEQ ID No: 2, SEQ ID No: 3 or SEQ ID No: 6 in the sequence listings;
2). Polynucleotides that encode the protein sequences of SEQ ID No: 4, SEQ ID No: 5, or SEQ ID No: 7 in the sequence listings;
3). DNA sequences having more than 90% homology with the DNA sequences defined by SEQ ID No: 1, SEQ ID No: 2, SEQ ID No: 3 or SEQ ID No: 6 in the sequence listings. These DNA sequences can encode proteins having the same or similar functions.
SEQ ID No: 1 in the sequence listings mentioned above contains 954 bases. It is an intact open reading frame. SEQ ID No: 1 has two starting sites, one is the base at 1-3 site at 5′ terminal, and another is the base at 274-276 site at 5′ terminal. Two complete cDNAs in SEQ ID No: 1 have two alternative tailing signals. When 5′ terminal in SEQ ID No: 1 is extended outward by 85 bases, and 3′ terminal is extended outward by 401 bases, SEQ ID No: 2 in the sequence listings is obtained. This gene contains 1440 bases. When 5′ terminal in SEQ ID No: 1 is extended outward by 85 bases, and 3′ terminal is extended outward 1130 bases, SEQ ID No: 3 in the sequence listings is obtained. This gene is consisted of 2169 bases. LAPTM4B gene localizes on chromosome 8q22.1.
In the sequence listings, SEQ ID No: 6 is the allelic gene of SEQ ID No: 1, consisting of 2264 bases. Its open reading frame starts from 17 to 1129 base. This sequence contains two tandemly arranged 19 bp DNA segments, the sequence of which is gcttgg agctccagca gct. These 19 bp DNA segments localized in nt 124-nt 161 in SEQ ID No: 6.
The human cancer related LAPTM4B protein possesses the amino acid sequence of 4, and/or 5, and/or 7. Or it consists of the sequence 4, and/or the sequence 5, and/or the sequence 7 after one or several amino acid residues are replaced, deleted, or added. However, the above altered sequence 4, and/or the sequence 5, and/or the sequence 7 still have the same or similar activity to the unchanged sequence 4, and/or the sequence 5, and/or the sequence 7.
Sequence 4 in the sequence listings consists of 317 amino acid residues encoded by the whole sequence of SEQ ID No: 1. Its molecular mass is 35 kDa and the putative isoelectric point is 9.05. Sequence 5 in the sequence listings contains 226 amino acid residues encoded by the segment of bases from 274th to 954th in the SEQ ID No: 1. Its molecular mass is 24 kDa, and the putative isoelectric point is 4.65. The sequence 7 in the sequence listings is a protein containing 370 amino acid residues.
LAPTM4B gene is widely expressed at different levels in sixteen normal tissues. Its transcriptive expression is very high in testis, cardiac muscle, and skeletal muscle, moderate in ovary, kidney, and pancreas, low in liver, spleen, small intestine, large intestine, and thymus, and is very low in lung and peripheral blood cells. In eight fetal tissues, the expression is high in heart, skeletal muscle, and kidney. In fetal livers, it is slightly higher than that in adult livers. However, its expression in some cancerous tissues is significantly upregulated. For instance, the Northern Blot analysis indicates that the transcription level in 87.3% (48/55) human hepatocellular carcinoma tissues is significantly higher than that in fetal livers and normal livers ( FIG. 1 -A). In situ hybridization ( FIG. 2 -A), immunohistochemistry ( FIG. 2 -B), and immunocytochemistry ( FIG. 2 -C) also indicate that LAPTM4B gene expression is especially high in hepatocellular carcinoma tissues, while its expression is relatively low in paired non-cancerous liver tissues ( FIGS. 2 -A and 2 -B). Among the five cell lines from hepatoma tissues tested, all except for HLE, SMMC-7721, QGY-7701, BEL7402 and HG116 are expressed highly ( FIG. 1 -B and FIG. 2 -C). It is important that highly over expressed protein product in hepatocellular carcinoma tissue and hepatocellular carcinoma cell line is mainly SEQ ID No: 4 LAPTM4B-35, while SEQ ID No: 5 LAPTM4B-24 only shows a slightly up regulation in its expression level. This results in a remarkable increase in the ratio of LAPTM4B-35 to LAPTM4B-24 proteins in the hepatocellular carcinoma tissue ( FIG. 2 -B). Although the expressions of LAPTM4B-35 and LAPTM4B-24 are slightly increased in the paired non-cancerous tissue, their ratio is the same as that in the normal liver (See Table 1). This is probably a precancerous sign of hepatocellular carcinoma. In addition, the expression levels of mRNA and the protein of LAPTM4B gene is negatively correlated with the differentiation of the hepatocellular carcinoma tissue. The hepatocellular carcinoma tissues in low differentiation are expressed highly, while the ones in high differentiation are expressed relatively low ( FIG. 1 -C). The Western Blot and the immunohistochemical method are used to determine the relationship of LAPTM4B gene with other cancers. The results indicate that LAPTM4B-35 protein expression is up regulated in some epithelium derived cancerous tissues and cell lines, such as stomach cancer, breast cancer, highly metastatic human lung cancer, and prostate cancer ( FIG. 11 ). Moreover, in syngeneic human lung cancer and prostate cancer cell lines, LAPTM4B-35 expression is greatly up regulated in cells of high metastasis potential compared with those of low metastasis potential. But in cell lines of human melanoma, either from in situ or metastatic cancer, it is not clearly expressed. Although LAPTM4B-35 is expressed at a low level in liver tissues of adult rats and mice, its expression is not obviously up regulated in either mouse ascetically grown hepatocellular carcinoma or in the regenerated rat liver under a normal proliferation status.
TABLE 1
Expression ratio of LAPTM4B-35 to LAPTM4B-24 in hepatocellular
carcinoma tissue, paired non-cancerous liver tissue and normal liver tissue
HCC
PNL
NL
LAPTM4B-35
13.32 ± 1.98
4.58 ± 1.31
2.78 ± 0.11
LAPTM4B-24
3.59 ± 1.78
1.76 ± 1.24
1.00 ± 0.02
LAPTM4B-35/
3.71
2.60
2.78
LAPTM4B-24 (Ratio)
P < 0.01 HCC vs. PNL and NL
LAPTM4B proteins in SEQ ID No: 4, SEQ ID No: 5 and SEQ ID No: 7 have four fragments of membrane-spanning sequences, one N-glycosylation site, a typical lysosome and endosome targeting signals in the cytoplasmic region. They all belong to the protein superfamily of the tetratransmembrane proteins. However, they have various number of phosphorylation sites. The experiment shows that SEQ ID No: 4 LAPTM4B-35 can form a complex in plasma membrane with the integrin α6β1 (Single specific receptor of laminin in the extracellular matrix) and the epidermal growth factor receptor (EGFR) ( FIGS. 14 -A, B, and C). This complex is colocalized in cell plasma membrane. It is possible that LAPTM4B-35 may integrate in the plasma membrane the proliferation signals from both extracellular matrix and the growth factor. This can further elucidate molecular mechanism of the anchorage-dependent cell growth of normal eukaryotic cells, i.e. the eukaryotic cell growth needs not only the stimulating signal from the growth factor, but also a definite stimulating signal from extracellular matrix. It represents a break through in understanding the regulation mechanism of the cell proliferation. Experiments demonstrate that tyrosine group (Tyr 285 ) in the cytoplasmic region of LAPTM4B protein C terminal can be phosphorylated ( FIG. 15 -A). When the cell is attaching onto the laminin substrate, its phosphorylation is increased sharply ( FIG. 15 -A) and can be completely inhibited by LAPTM4B-EC2-pAb antibody ( FIG. 15 -B), but the non-correlated antibody does not show any inhibitory effect ( FIG. 15 -C). After the phosphorylation, Tyr 285 forms a site to bind with the SH2 domain of intracellular signal molecules. In the meantime, N terminal and C terminal sequences of LAPTM4B contain Pro-rich domains and binding sites of the typical SH3 I domain. The above results indicate that SEQ ID No: 4 LAPTM4B-35 protein may be an important docking protein for signal transduction, or an organizer of the special microdomain in the plasma membrane. It can recruit related signal molecules from both inside and outside of the cells to complete the signal transduction for cell proliferation, differentiation, and apoptosis. Experimental results show that the transfection of mouse NIH3T3 cells and HLE human hepatocellular carcinoma cells by cDNA in SEQ ID No: 4 produces stable transfected and LAPTM4B-35 over expressed NIH3T3-AE and HLE-AE cell lines. The growth curves ( FIG. 4 ), the incorporation of 3H-TdR ( FIG. 5 ), and the cell numbers in S phase of cell cycle ( FIG. 6 ) all demonstrate that the rate of cell proliferation is greatly increased. Moreover, the proliferation of transfected cells shows less dependence on the growth factor in serum, and the transfected cells can form large colonies in soft agar. Inoculation of NIH mouse with NIH3T3-AE cells can form a moderate malignant fibrosarcoma ( FIG. 7 ), indicating the over expression of LAPTM4B-35 induces out of control of the cell proliferation. Also migration capability of the HLE-AE cells is strengthened and its capability to invade the Matrigel is remarkably enhanced, indicating that the over expression of LAPTM4B-35 accelerates the development of cell malignant phenotype. On the contrary, the cDNA of SEQ ID No: 5 (An encoding sequence where 91 amino acids in the N terminal of LAPTM4B-35 is truncated) transfected mouse BHK, NIH3T3, and HLE hepatocellular carcinoma cell lines cannot survive for a long time. The result shows that the 91 amino acid sequence on the N terminal of SEQ ID No: 4 LAPTM4B-35 protein play a crucial role in regulating cell proliferation. LAPTM4B-35 protein and LAPTM4B-24 protein have reciprocal, antagonistical functions in cell proliferation and survival. The overexpression of LAPTM4B-35 accelerates cellular malignant transformation, while the overexpression of LAPTM4B-24 facilitates the cell death. Their expression equilibration and regulation are pivotal to the carcinogenesis and progression of malignant cancer. LAPTM4B gene may belong to the proto-oncogene family. In cancer treatment, inhibiting SEQ ID No: 4 LAPTM4B-35 expression and strengthening SEQ ID No: 5 LAPTM4B-24 expression may suppress the growth of hepatocellular carcinoma and reverse its malignant phenotype or progressively slow down its development. Furthermore, the overexpression of LAPTM4B-35 also promotes upregulation of the cell cycle regulators, such as cyclin D1 ( FIG. 13 -A) and cyclin E ( FIG. 13 -B), and also the over expression of some proto-oncogenes, such as c-Myc ( FIG. 13 -C), c-Jun ( FIG. 13 -D), and c-Fos ( FIG. 13 -E) etc.
The monoclonal and polyclonal antibodies for SEQ ID No: 4 LAPTM4B-35 protein epitopes, such as polyclonal LAPTM4B-EC2 232-241 -pAb for SEQ ID No: 4 LAPTM4B-35 in the secondary extracellular region, polyclonal antibodies (LAPTM4B-N 1-99 -pAb and LAPTM4B-N 28-37 -pAb) for SEQ ID No: 4 LAPTM4B-35 N terminal sequence, and monoclonal antibodies for LAPTM4B are important in studying the effects of LAPTM4B-35 and LAPTM4B-24 in cancer diagnosis and treatment ( FIGS. 2, 3, 8, 11, 12, 14, 15 ). For example, LAPTM4B-EC2 232-241 -pAb, LAPTM4B-N 1-99 -pAb polyclonal antibodies and LAPTM4B-N 1-99 -mAb monoclonal antibody can be used to analyze LAPTM4B protein expression, intracellular localization, separation and purification, and protein-protein interaction. They can also be used to detect the antibody and antigen of LAPTM4B in blood ( FIG. 8 ). Moreover, LAPTM4B-EC2 232-241 -pAb can inhibit cancer cell proliferation ( FIG. 12 ), Tyr 285 phosphorylation of LAPTM4B protein ( FIG. 15 -B), and the phosphorylation and activation of signal molecules FAK ( FIG. 16 -A) and MAPK ( FIG. 16 -B). Therefore, all the monoclonal and polyclonal antibodies for SEQ ID No: 4 LAPTM4B-35 protein epitope are encompassed in this invention.
SEQ ID No: 8 is the promoter sequence of LAPTM4B gene. To study the regulation of LAPTM4B gene expression, the LAPTM4B gene promoter and the upstream sequence SEQ ID No: 8 are cloned. There are no typical CCAAT (TTGCGCAAT), TATA cassettes in LAPTM4B gene promoter region. But various binding sites of transcription factors exist in the upstream region of LAPTM4B promoter, such as CREBP1/c-Jun, CEBP, PAX2/5/8, GATA, STAT, c-Ets-1, E2F, LYF-1, and c/v-Myb ( FIG. 17A ). These transcription factors may specifically regulate LAPTM4B expression in cells of various tissues. The abnormal expression and activation of these transcription factors in cancer cells possibly lead to an unbalanced expression of LAPTM4B proteins. Moreover, there are two highly homologous repeating sequences in the upstream domain of LAPTM4B promoter. It is worthwhile to study whether they are responsible to the regulation of LAPTM4B expression. A series of vectors consisting upstream region sequences of LAPTM4B promoter with different lengths—promoter-5′ UTR-35 bp encoding region—luciferase reporting gene is constructed, and these vectors are used to transfect into BEL7402 cells and HLE cells from human hepatocellular carcinoma HCC. As shown in FIG. 17 , the cells transfected with various vectors all show luciferase activity with various intensities, indicating the transcription activities in these segments. The smallest fragment is a DNA segment (pGL-PF4) at about 38 bp in the upstream region of the transcription starting site. It possesses a basic promoting activity and functions as LAPTM4 core promoter. The activity of pGL-PF4 transfectant in BEL7402 is 20% of the reference promoter SV40, while the activity is low in HLE, only 6% of SV40 activity, about ⅓ of that in BEL7402. These data partially reflect the natural activity of LAPTM4B promoter in these two cell lines. It is consistent with the Northern blot results, where mRNA expression is high in BEL-7402 cell line and low in HLE cell line. Additionally, pGL3-PF4 transfectant reveals dramatically different activities in these two cells. Its activity in BEL-7402 cells is 7 times higher than that in HLE cells. Apparently, different regulative mechanisms of LATPM4B gene transcription exist in BEL7402 and HLE cell lines.
In embodiments of this invention, the genome DNA is genotyped in order to determine the relationship between different LATPM4B genotypes and susceptibility of hepatocellular carcinoma. LATPM4B has two alleles, LATPM4B*1 and LATPM4B*2, i.e., SEQ ID No: 6, is derived by PCR cloning. As shown in FIG. 9 , the difference between alleles *1 and *2 is the 19 bp sequence in the first exon 5′ UTR. Allele *1 has only one such sequence (nt 124˜142dup, while *2 contains two such sequences in a tightly tandem arrangement (124-142dup, taking G at the transcription starting site TSS as +1 numbering standard). The insertion of the 19-bp sequence would eliminate the stop codon in 5′UTR in the corresponding *1 allele by a triplet shift. As a result, the open reading frame may be extended upstream by 53 amino acids at N terminus of the protein. The encoded protein by SEQ ID No: 6 then should contain 370 amino acid residues (SEQ ID No: 7). LATPM4B genotypes detected in human population are *1/*1, *1/*2 and *2/*2, respectively ( FIG. 10 ). Studies show that the risk of developing hepatocellular carcinoma for individuals with LATPM4B genotype *2/*2 is 2.89 times higher than individuals with non-*2/*2 type (Table 2). However, LATPM4B genotype in patients with esophagus carcinoma shows no difference from the normal population (Table 3). This indicates that LATPM4B *2/*2 genotype correlates especially to susceptibility of hepatocellular carcinoma. As a result, LATPM4B allele LATPM4B*2 provided by this invention can be used as a target to screen and diagnose people susceptible to hepatocellular carcinoma or having a high risk to develop hepatocellular carcinoma. Particularly, using LATPM4B *2/*2 genotype as a target to screen highly susceptible or high risk people can be more accurate. *1/*1, *1/*2 and *2/*2 of LATPM4B genotypes, LATPM4B*2 encoded proteins or their antibodies, and/or LATPM4B extender and scavenger from human genome can all be used to screen people who are susceptible to hepatocellular carcinoma or having a high risk to develop hepatocellular carcinoma.
The expression vectors containing sequences described in SEQ ID No: 1, 2, 3, 6, 8, the transfection cell lines containing SEQ ID No: 1, 2, 3, 6, 8 sequences, and the primers amplifying SEQ ID No: 1, 2, 3, 6, 8 are all encompassed by this invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 -A is the Northern Blot analysis profiles indicating the transcriptive expression of the gene of this invention in normal human liver, normal fetus liver and hepatocellular carcinoma tissues.
FIG. 1 -B is the Northern Blot analysis spectrum indicating the transcriptive expression of the gene of this invention in the human hepatocellular carcinoma cell lines.
FIG. 1 -C is a diagram showing the relationship of the expression level of the gene of this invention in human hepatocellular carcinoma tissues and the cancer differentiation status.
FIG. 2 -A is a diagram of hybridization in situ of hepatocellular carcinoma tissue. The LATPM4B mRNA in hepatocellular carcinoma nodule shows a strong positive staining.
FIG. 2 -B is an immunohistochemical diagram, where LATPM4B protein in hepatocellular carcinoma nodule shows a strong positive staining.
FIG. 2 -C is an immunocytochemical diagram, where LATPM4B protein is shown to exist in the transfected cells.
FIG. 3 presents a Western Blot analysis diagram, where the expression spectra of LATPM4B-35 and LATPM4B-24 proteins encoded by the gene of this invention are shown in the tissues of normal liver (NL), hepatocellular carcinoma (HCC), and paired non-cancerous liver (PNL).
FIG. 4 shows a growth curve of the accelerated proliferation of cDNA-transfected cells of this invention.
FIG. 5 shows a column diagram, where the DNA synthesis of LAPTM4B cDNA-transfected cells of this invention is increased.
FIG. 6 is a pie diagram showing an increase of cell numbers in S phase in cDNA-transfected cells of this invention (Flow cytometry analysis).
FIG. 7 shows the oncogenic effect of cDNA-transfected cells of this invention on mouse (SEQ ID No. 19).
FIG. 8 is a histogram showing the level of the antigen of this invention in the serum of patients with hepatocellular carcinoma.
FIGS. 9 A and B shows schematic diagrams of the LAPTM4B promoter and its first exon and the partial sequence (SEQ ID No. 19 and SEQ ID No. 20) of LAPTM4B alleles of this invention.
FIG. 10 shows the genotypes distribution of LAPTM4B alleles of this invention in human population.
FIG. 11 is an immunohistochemical diagram of various cancer tissues derived from epithelium.
FIG. 12 is a column diagram showing the inhibitory effect of LAPTM4B-EC2-pAb antibody on proliferation of hepatocellular carcinoma cells.
FIGS. 13 -A, 13 -B, 13 -C, 13 -D, and 13 -E are the Western Blot analysis diagrams showing respectively that the expressions of cyclin D1, cyclin E, c-Myc, c-Fos, and c-Jun of cDNA-transfected cells of this invention are up-regulated.
FIGS. 14 -A, 14 -B, and 14 -C are the analytical diagrams of the co-immuno precipitation, revealing respectively the interactions of the gene product (LAPTM4B protein) of this invention with α 6 β 1 integrin and with the epidermal growth factor receptor (EGFR).
FIGS. 15 -A, 15 -B, and 15 -C are the analytical diagrams of the immunoprecipitation, showing the Tyr phosphorylation of LAPTM4B protein and the inhibitory effect of LAPTM4B-EC2-pAb on Tyr phosphorylation.
FIGS. 16 -A and 16 -B are the analytical diagrams of the co-immuno precipitation showing respectively that LAPTM4B is involved in FAK-MAPK signal transduction pathway.
FIG. 17 is a plot showing the transcriptive activity of various fragments of LAPTM4B promoter of this invention (SEQ ID No. 8).
DETAILED DESCRIPTION OF THE INVENTION
Sources of Patients and Normal Control Group:
57 cases of hepatocellular carcinoma patients, 50 males and 7 females, ranged in age from 35-70. Their average age was 54±6.0. The tissues tested came from surgically excided specimens. The blood samples for the control group were collected from 206 similarly aged people with no symptoms and no cancer according to clinic tests and from 209 new born babies' umbilical veins.
109 esophagus cancer patients, 76 males and 33 females, ranged in age from 30-70. Their average age was 55±5.4. The test tissues came from surgically excided specimens. 116 people with no symptoms and no cancer, as determined by clinical examination, were selected as the control group S. Their blood samples were taken for testing. All the samples were extracted to obtain genomic DNA.
Statistical Method
Chi-square (X 2 ) measurement and single factor ANOVA variance were used to treat and analyze the data.
Example 1
Northern Blot Analysis of LAPTM4B Expressions in Four Types of Liver Tissues at Various Proliferation and Differentiation Status
Four types of liver tissues at various proliferation and differentiation status were chosen. They were from normal adult livers (NL, with very little proliferation and high differentiation), fetus livers (FL, at vigorous proliferation and low differentiation), hepatocellular carcinoma (HCC, out of controlled proliferation and abnormal differentiation), and paired non-cancerous livers (PNL, generally is of precancerous stage in an active proliferation status). The Northern Blot analysis was used to detect the transcription of gene in these tissues. RNA samples were extracted from 5 normal adult liver tissues freshly obtained from surgical excision: 5 liver tissues from abortive fetus, 55 HCC tissues, and 55 paired non-cancerous liver tissues. After electrophoretic separation, they were transferred to a nylon film and hybridized by Dig labeled probe. The film was washed at 68° C. and the hybridization signals were developed according to the manual. The results are shown in FIG. 1 . Band 1 was the sample from fetus livers. Band 2 was from the normal adult liver sample. Bands 3, 5, 7, and 9 were the samples from HCC. Bands 4, 6, 8, 10 were from PNL tissues. The results show that the expression of LAPTM4B in various liver tissues has the following order: HCC tissue>PPNL tissue and fetus liver tissue>normal adult liver tissue.
Example 2
Clonings of LAPTM4B Gene, Allele, and Promoter
2-1 LAPTM4B Gene Cloning
By using fluorescence differential display technique, an unknown gene cDNA segment (LC27) was obtained from differential display spectrum in four types of human liver tissues in different proliferation and differentiation status, such as normal adult livers (NL), fetus livers (FL), cancerous livers (HCC), and paired non-cancerous liver (PNL). The LC27 segment (426 bp) was elongated by splicing homogenous sequences according to the EST to the 5′ direction, and followed by RACE (rapid amplification of cDNA ends) and the high temperature RT-PCR techniques. Two full-length cDNA sequences, i.e., SEQ ID No. 2 and 3, were produced, and then confirmed by sequencing and BLAST program analysis.
2-2. LAPTM4B Promoter Cloning
The sequence of upstream region of the first exon of LAPTM4B gene at 5′ terminal was obtained by biological informatics, and primers F1 and R1 were designed. Using human genomic DNA from HCC as the template, LAPTM4B promoter and the upstream sequence was obtained by PCR using Platinum Pfx DNA polymerase. After Xho I and hind III enzyme cutting, they were inserted into pGL3-Basicvector to form pGL3-PF1, and its sequence was determined (i.e., the test result see portion a of FIG. 16 ).
As shown in FIG. 17 a , no typical CCAAT (TTGCGCAAT) and TATA boxes were found in the LAPTM4B promoter sequence. In the upstream region of LAPTM4B promoter, there are many binding sites for a variety of transcription factors, such as CREBP1/c-Jun, CEBP, PAX2/5/8, GATA, STAT, c-Ets-1, E2F, LYF-1, and c/v-Myb. They may function on regulation of LAPTM4B expression. In hepatocellular carcinoma, the abnormal expression and activation of these transcription factors possibly lead to an unbalanced expression of LAPTM4B proteins. Moreover, the LAPTM4B upstream region contains two highly homologous repeating sequences. It is worthwhile to further study on whether they have any effect on LAPTM4B expression regulation.
2-3. Cloning and Sequence Analysis of LAPTM4B Alleles
2-3-1. DNA Separation
Genome DNA was extracted from blood lymphocytes or cancer tissue samples from surgical excision of hepatocellular carcinoma and esophagus carcinoma according to the standard phenol-chloroform method.
2-3-2. Cloning and Sequence Analysis of the Alleles
By using the same procedures for the promoter sequence cloning, two primers,
(SEQ ID No. 11 F1: 5′ GCG CTCGAG GCTCCAGGTGGAAGAGTGTGC 3′,
inducing XhoI enzyme cutting site at 5′ terminal sequence as indicated by underlining), and
(SEQ ID No. 16 R1: 5′ GCG AAGCTT GGACTTGGCCATGTGACCCG 3′,
inducing XhoI enzyme cutting site at 5′ terminal sequence as indicated by underlining), were designed and synthesized based on LAPTM4B gene sequence SEQ ID No. 3. The promoter sequence and its anterior sequence in the first exon of LAPTM4B were then cloned from human genomic DNA by PCR. The pGL3-PF1 vectors constructed from various human genomic DNA were sequenced to screen the LAPTM4B alleles. The original LAPTM4B sequence was designated as LAPTM4B*1. The other one was designated as LAPTM4B*2, i.e., SEQ ID No. 6 in the sequence listings. FIG. 9(A) shows the schematic diagrams of the LAPTM4B promoter and its first exon. The rectangle frame indicates the first exon, the black color area represents the encoding area, the white color is the non-coded area, and the gray area shows a 19 bp DNA sequence. The horizontal line representing promoter part and F1, F2, R1, and R2 are where the four primers are located. “A” in the start codon ATG is defined as +1 in the sequence. FIG. 9 (B) shows the partial sequences of the LAPTM4B alleles and their sequencing graphic spectra. The underlined part is a 19 bp DNA sequence.
The results reveal that LAPTM4B*1 contains one copied 19 bp DNA sequence and LAPTM4B*2 has two copied 19 bp DNA sequences, which are linked in the non-coded area (nt −33-−15) of the first exon of LAPTM4B*1.
The sequence analyses indicate that LAPTM4B*2 and LAPTM4B*1 possess the same promoter. There is no difference in sequences between LAPTM4B alleles *1 and *2 promoters.
2-3-3. LAPTM4B Genotype Classification
E2 (5′ GCCGACTAGGGGACTGGCGGA 3′, SEQ ID No. 9) and R2 (5′ CGAGAGCTCCGAGCTTCTGCC 3′, SEQ ID No. 10)
primers were designed and synthesized. A partial sequence of the first exon of LAPTM4B was amplified by PCR using templates of genomic DNA from normal people, hepatocellular carcinoma, and esophagus carcinoma tissues. PCR conditions were as follows: 96° C. pre-denature for 5 min; 94° C. for 30 s, 68° C. for 30 s, 72° C. for 1 min, 35 cycles; 72° C. for 5 min; then the PCR products were conducted to 2% Agarose gel electrophoresis analysis.
FIG. 10 shows LAPTM4 gene *1/*1, *1/*2, and *2/*2 three types in human population.
Example 3
Construction of the Reporter Plasmids and Analysis of the Promoter Activity
A series of vectors, that contain the upstream sequences with various length of the LAPTM4B promoter, 5′UTR, the 35 bp encoding sequence in exon and the luciferase reporting gene, were constructed, i.e., the LAPTM4B gene promoter and the upstream sequence was cut by Xho I and I Hind III enzyme and connected to pGL3-Basic vector to form pGL3-PF1, and identified by sequencing. Then pGL3-PF1 was used as a template, primers F2, F3, and F4 vs. R1 were used to amplify by PCR, respectively, to construct vectors, pGL3-PF2, pGL3-PF3, and pGL3-PF4 which contain promoter segments with various lengths and luciferase gene. These constructs were identified by sequencing.
The sequences of these primers are as follows:
F1: 5′GCGCTCGAGGCTCCAGGTGGAAGAGTGTGC 3
(nt −1341-−1321, SEQ ID No. 17)
F2: 5′ GCGCTCGAGTAA AAACGCTGTGCCAGGCGT 3′
(nt −881-−861, SEQ ID No. 18)
F3: 5′ CCGCTCGAGTACCGGAAGCACAGCGAGGAT 3′
(nt −558-−538, SEQ ID No. 13)
F4: 5′ GCGCTCGAGAGTAGAAGGGAAGAAAATCGC 3′
(nt −38-−18, SEQ ID No. 14)
R1: 5′ GCGAAGCTTGGACTTGGCCATGTGACCCG 3′
(nt 172-191, SEQ ID No. 15)
These vectors were used to transfect BEL-7402 cells and HLE cells separately and the promoter activities were measured. As shown in FIG. 17 b , the vector-transfected cells all have luciferase activities with different intensities. pGL3-PF3 showed similar activity in both BEL-7402 cells and HLE cells, which was about 27% of the SV40 promoter (pGL3-Promoter) activity. When comparing it with pGL3-PF4 activity, however, there was almost no difference in BEL-7402 cells. In HLE cells, pGL3-PF3 activity was 7 times higher than pGL3-PF4. As shown in FIG. 17 a , pGL3-PF3 (−41˜−558) has many potential binding sites for transcription factors. One or many of them, especially c-Ets-1, may play a regulating role in HLE cells and make the luciferase activities of pGL3-PF3 and pGL3-PF4 tranfectants remarkably different in HLE cells. The pGL3-PF3 activity is higher than that of pGL3-PF1 and pGL3-PF2 in both BEL-7402 and HLE cells, implying that some negatively regulatory factor exists. One or more of these negatively regulatory factors bind with the promoter upstream target sequence (−558 upstream) to induce a downregulated LAPTM4B gene expression. This suppressive effect was stronger in HLE cells than in 7402 cells. This means that HLE cells may contain some factors that strongly suppress the expression of LAPTM4B. The Northern Blot analysis presented in FIG. 1 -B also shows a low expression of LAPTM4B in HLE cells, supporting the above hypothesis. The pGL3-PF2 vector contains two DNA repeating fragments (−41˜−328, −574˜−859), which is one more DNA fragment (−574˜−859) than pGL3-PF3. pGL3-PF3 exhibits higher activity than pGL3-PF2 in both cells. This result indicates that the two repeating sequences negatively regulate gene transcription. They have many potential binding sequences for the transcription factors and provide two binding sites for each negatively regulating factor. Since many transcription factors often form dimers, they have to bind with two target sequences to be able to function. In the case of pGL3-PF3, which can only provide one binding site, no function is shown. Since the pGL3-PF3 transfectant has a disinhibitory effect, its activity is higher than other vector transfectants.
Example 4
Western Blot Analysis of LAPTM4B Protein Expression
The tissue sample was placed on ice and cut into small pieces by scissors. 0.1 gram of wet tissue was selected and placed in a manually operated homogenizer. 1 mL lysis buffer was added in each tube and the mixture was thoroughly homogenized. The lysate was transferred to a fresh tube and centrifuged at 4° C., 12 000 g for 10 min to remove the debris. If cells are used, the cells in a culture dish were digested with 0.25% trypsin buffer, followed by two PBS rinses and centrifuged at 500 g for 3 min. The cleared supernatant was collected, and the proteins in the supernatant were separated by SDS-PAGE electrophoresis, and then transferred to the NC membrane. The membrane was blocked at 4° C. overnight with 5% non-fat powdered milk in a TBS buffer containing 0.05% Tween 20. Then it was incubated with the rabbit polyclonal antibody, LAPTM4B-EC2 232-241 -pAb (1:500 dilution) or mouse Anti-FLAG M2 monoclone antibody (Sigma, 1:750 dilution) at room temperature for 2 hours, and then rinsed with TBS for three times. It was further incubated with a peroxidase-coupled second antibody (IgG), such as goat anti rabbit or goat anti mouse (1:3000 dilution), for 2 hrs, followed by three rinses with a TBS buffer (pH 8.0, containing 0.05% Tween 20). The last wash was with a buffer containing no Tween 20. ECL (Santa Cruz) was used to expose the positive bands (performed as manufacturer's instructions). When two antibodies were sequentially hybridized in one membrane, the ECL exposed membrane was rinsed first with TBS followed by washing with 30 mL TBS (2% SDS and 210 μL β-mercaptoethanol) for 30 min at room temperature. The 30 min TBS rinse removed the previous antibody and its signal in the membrane, which then could be used for the second hybridization. FIG. 3 shows that LAPTM4B-35 was over expressed in HCC tissues and HCC cell lines.
Example 5
Regulatory Effect of the Gene of this Invention on Cell Proliferation and the Malignant Phenotype of Cancer Cells as Demonstrated by a Full-Length cDNA Transfection
Using pGEMT-E2E7 plasmid as a template and the PCR method, a full length or partial cDNA, or the reading frame of LAPTM4B gene was amplified by PCR with primers A, or B and E, and the Pfx DNA polymerase. BamHI enzyme cutting site (GGATCC) and ribosome binding site sequences (GCCACC) were introduced in primer A and B at 5′ terminal and EcoRI enzyme cutting site (GAATTC) was incorporated in the primer E. The amplified products AE and BE were digested by restriction enzymes BamHI and EcoRI, purified, and ligated into pcDNA 3.0 vector. They were transformed conventionally to DH5 E. coli and the positive clone was selected, and the constructed plasmid was sequenced for identifying. The constructed plasmids were named as pcDNA3/AE and -BE, respectively. pcDNA3/AE contains a full-length ORF, while pcDNA3/BE contains the ORF starting from the second ATG to TAA. Compared with pcDNA3/AE, pcDNA3/BE-encoded protein is missing 91 amino acids at the N terminal.
Mouse BHK, NIH3T3 cell lines and human hepatocellular carcinoma HLE cell line, in which the expression of LAPTM4B were all at very low level, were transfected by pcDNA3/AE or -BE, and clones that LAPTM4B expression were stable and high were selected. The total viable cell numbers were determined by the acidic phosphatase method and the cell growth curve was plotted. The cell cycle was analyzed by the flow cytometry. The expression levels of cell cycle-regulating protein, including cyclin D1 and Cyclin E, and proto-oncogene products, including c-Myc, c-Fos, and c-Jun (transcription factors for regulating cell proliferation) were measured by the Western Blot analysis. The results show that the cell proliferation was accelerated after being transfected by LAPTM4B-AE expressive plasmid ( FIG. 4, 5, 6 ). Expressions of cyclin D1, cyclin E, c-Myc, c-Fos, and c-Jun were also greatly increased ( FIG. 13 -A, B, C, D, E, respectively). But the dependence of growth on serum in LAPTM4B-35-overexpressed cells was greatly reduced (HLE-AE cell proliferation proceeded normally in 1% FCS, but HLE and HLE-MOCK cells stop proliferation at the same condition). In the meantime, the anchorage-dependent cell growth of HLE-AE cells was clearly weakened. Large colonies of HLE-AE cells were formed in the soft agar, which indicates that this gene participated in the regulation of cell proliferation and its over expression (activation) was related to the dysregulation of cell proliferation. Furthermore, the migrating capability of HLE-AE cells was also enhanced (The HLE-AE cells that migrated through the membrane pores were increased from 1216±403.8 for the control to 4082.5±748.8). Its capability to invade Matrigel was also greatly increased (from 25±12.73 cells for the control to 1325±424.26 cells). The results show that LAPTM4B over expression promotes the development of cell malignant phenotype. On the contrary, BHK-BE, NIH3T3-BE, and HLE-BE cells transfected by LAPTM4B-BE expressive plasmid could not form clones. They were all dead within three weeks. These results demonstrate that LAPTM4B-24 plays antagonistic roles to LAPTM4B-35.
Example 6
Tumorigenic Effect of LAPTM4B cDNA-Transfected Cells on Mouse
Six-week old male mice were randomly selected and divided into three groups: In the first control group, the mice were injected with physiological saline. In the second control group, the mice were inoculated with the pcDNA3 MOCK (no-load plasmid) transfected cells by. In the test group, all the mice were inoculated with pcDNA3/AE (a plasmid containing full-length cDNA) transfected NIH3T3 cells. Each mouse was subcutaneously inoculated with 2×10 6 cells. There were four to six mice in each group. The mice were sacrificed after 21 days inoculation and dissected. As shown in FIG. 7 , two mice (half of inoculated mice) in the test group developed a clearly moderate malignant fibrosarcoma (A, B); the other two mice were identified as lymphatic tissue at the inoculated sites (C, D). In contrast, twelve mice in the two control groups showed no sign of tumor formation after being inoculated for 86 days.
The results in Examples 4, 5, and 6 indicate that LAPTM4B may be a novel proto-oncogene.
Example 7
Primary Analysis of LAPTM4B Antigen in the Serum of Patients with Hepatocellular Carcinoma by the ELISA Method
96 wells culture plates were coated with sera in various dilutions from HCC patients and normal people by known agreement at 4° C. overnight. Each well was washed with 0.5% Tween-20 washing solution, and then 2% BSA was added for blocking at room temperature for 1 hour. Then LAPTM4B-EC2-pAb antibody in various dilutions was added and incubated for 2 hours at room temperature. The goat anti-rabbit antibody labeled by horseradish peroxidase (1:1000 times dilution) was added after PBS washing. After standing at room temperature for 2 hours and one PBS washing, 1 g/mL o-phenyldiamine was added for 10-15 minutes to develop color and H 2 SO 4 was used to stop the reaction. The microtiter for enzyme analysis was used to measure OD. at 490 nm and the antigen level was estimated. The results are shown in FIG. 8 . Clearly, the sera of patients with hepatocellular carcinoma contained higher level of LAPTM4B antigen than that from normal people, indicating that LAPTM4B has a potential to become a new marker for hepatocellular carcinoma diagnosis.
Example 8
Functional Determination of LAPTM4B Protein in Signal Transduction by Co-Immunoprecipitation and Antibody Inhibition Analysis
The cell lysate was prepared according to the method in Example 4. The first antibody was added to the supernatant. After 1 hour's shaking at 4° C., 50 μL protein G-Agarose suspension was added and the mixture was shaken at 4° C. for at least three hours or overnight. The immunocomplex precipitate was collected after centrifuging at 12000 g for 20 seconds. The complex was re-suspended by adding 1 mL washing buffer I and shaken at 4° C. for 20 min. The mixture was centrifuged at 12000 g for 20 seconds and the supernatant was removed carefully. This step was repeated once. Then the complex was re-suspended by adding washing buffer II, shaken at 4° C. fro 20 min., and centrifuged at 12000 g for 20 seconds. The supernatant was removed carefully. The last two steps were repeated once. The complex was re-suspended by adding washing buffer III, shaken at 4° C. fro 20 min, and followed by 12 000 g centrifugation for 20 seconds. The supernatant was removed completely. 50 μL 1×SDS loading buffer was added in the precipitate and the mixture was boiling in 100° C. water bath for 5 min to denature and dissociate the immunocomplex in the sample. After 12000 g centrifugation for 20 second, the supernatant was removed and analyzed in SDS-PAGE apparatus.
BEL-7402 cell was preincubated for 0, 10, 20, and 40 min, respectively, on LN-1 substance in serum free medium. Co-immunoprecipitation was performed with LAPTM4B-EC2-pAb from the cell lysate. The co-immunoprecipitates were respectively adsorbed by Protein G-Sephorose, centrifuged, and analyzed by 10% non-reductive SDS-PAGE. Then the phosphorylations of LAPTM4B, FAK and MAPK were analyzed separately by the Western Blot with p-Tyr mAb.
BEL-7402 cells were preinoculated separately with LAPTM4B-EC2-pAb (15 μg/mL) and anti-Glut2 (15 μL/mL) antibodies at 37° C. under 5% CO 2 for 2 hrs, and then seeded on LN-1 substance and incubated for indicating time. Under the same conditions, the anti-Glut2 antibody treated cells and no antibody treated cells were used as control. The cell lysate in each group was analyzed by the Western Blot analysis with p-Tyr mAb. The inhibitory effects of various antibodies on phosphorylation of LAPTM4B were analyzed. The results show that LAPTM4B-35 was phosphorylated peakly when human hepatocellular carcinoma BEL-7402 cells were attached on laminin substrate. The phosphorylation of LAPTM4B-35 reached the highest level in 10 min after cell attachment ( FIG. 15 -A). Meanwhile LAPTM4B-EC2-pAb could inhibit almost completely its phosphorylation ( FIG. 15 -B), while the anti-Glut2 (an antibody against a non-related plasma membrane protein Glut2) showed no such inhibitory effect ( FIG. 15 -C). On contrary, LAPTM4B-24 cannot be phosphorylated. The phosphorylation of LAPTM4B-35 Tyr 285 would form a binding site for signal molecules that contain SH2 domain. In the meantime, LAPTM4B-35 itself presents typical binding sites for signal molecules that contain SH3 domain. Therefore, LAPTM4B-35 functions most likely as a very important docking protein of molecules for signal transduction or a special organizer of membrane microdomain. It could recruit signal molecules related inside or outside cells, so that to play pivotal roles in signal transduction associated with cell proliferation, differentiation and apoptosis. Moreover, the attachment of human hepatocellular carcinoma cells on laminin substrate can also cause Tyr phosphorylation of the cytoplasmic signal molecule FAK ( FIG. 16 -A), and the LAPTM4B-EC2-pAb and anti-integron α 6 mAb against the epitope of the extracellular region of α6 both can prevent FAK phosphorylation without affecting the expression level of FAK protein by preincubating with BEL 7402 cells. Similarly, the attachment of BEL 7402 cells on laminin substrate can also induce Tyr phosphorylation of the signal molecule MAPK ( FIG. 16 -B), and its phosphorylation can be inhibited by preincubating cells with LAPTM4B-EC2-pAb without changing the expression level of MAPK protein. These results indicate that the interaction between LAPTM4B-EC2 domain (the second extracellular region) and integrin α6 subunit plays an important role in triggering FAK-MAPK signaling pathway.
The results from Examples 4-8 suggest that LAPTM4B-35 can be potential targets of drugs for regulating cell proliferation, differentiation, and apoptosis.
Example 9
LAPTM4B Genotype Classification
LAPTM4B genotypes in genomic DNA from blood of normal individuals and patients with hepatocellular carcinoma were detected by PCR. Two primers were designed and synthesized according to the flanking sequence of 19 bp DNA sequence in LAPTM4B gene sequence 3:
(SEQ ID No. 9)
E2: 5′ GCCGACTAGGGGACTGGCGGA 3′
(SEQ ID No. 10)
R2: 5′ CGAGAGCTCCGAGCTTCTGCC 3′
The partial sequence of the first exon was amplified using genomic DNA as a template. PCR conditions were as follows: 96° C. pre-denature for 5 min, 94° C. for 30 sec, 68° C. for 30 sec, 72° C. for 1 min, 35 cycles, 72° C. extension for 5 min. PCR products were analyzed by 2% agarose gel electrophoresis and the results are shown in FIG. 10 . The lanes 1, 6, 12, and 13 represent a 204 bp nucleotide segment in LAPTM4B*1/*1. The lanes 5, 8, 9, 14, and 15 represent a 223 bp nucleotide segment in LAPTM4B*2/*2. The lanes 2, 3, 4, 7, 10, and 11 represent 204 bp and 223 bp nucleotide segments in LAPTM4B*1/*2. Line M is the marker. The results reveals that in the homozygous gene pair of *1/*1 or *2/*2 either the 204 bp or 223 bp DNA segment was amplified, while in *1/*2 hybrid gene pair 204 bp and 223 bp DNA segments were both amplified simultaneously. Therefore, the genotype of LAPTM4B in Chinese population can be classified as LAPTM4B*1/*1, *1/*2, and *2/*2 ( FIG. 10 ).
Example 10
Frequency Distribution of LAPTM4B Genotypes and Alleles in Normal People and Patients with Hepatocellular Carcinoma
In one of the embodiments of the present invention, the occurrence frequency of LAPTM4B genotypes in 209 normal Chinese and 57 patients with hepatocellular carcinoma was analyzed and compared in Table 2. The Hardy-Weinberg equation was used to get the expectancy analysis. The frequency of LAPTM4B allele *1 and *2 from patients with hepatocellular carcinoma differs significantly from that of normal people. Their ratios are 0.5175: 0.6746 and 0.4825: 0.3254, respectively. The occurrence frequencies of LAPTM4B allele *1 and *2 in a normal population are 0.6746 and 0.3253, while the occurrence frequency of LAPTM4B allele *1 and *2 in patients with hepatocellular carcinoma are 0.5175 and 0.4825. The occurrence frequency of genotype *1/*1 (p=0.029) and *2/*2 (p=0.003) in the group of hepatocellular carcinoma patient shows a significant statistical difference from its control group. In the hepatocellular carcinoma patient group, only 29.8% is of *1/*1, while in the normal control group, 45.93% is of *1/*1. The occurrence frequency of *2/*2 genotype in the hepatocellular carcinoma patient group is 26.32% as compared to 11.01% in the control group, therefore its occurrence frequency is increased significantly (p<0.01). The analysis shows that the risk suffering from HCC of individuals in *2/*2 genotype of is 2.89 times greater than that in other genotype in developing hepatocellular carcinoma. Thus, the LAPTM4B*2/*2 genotype is correlated with the susceptibility of developing hepatocellular carcinoma.
As shown in Table 3, patients with different LAPTM4B genotypes did not show any differences in hepatocellular carcinoma Grade, stage, or HBV infection. 83.3% of the HCC patients have a positive HBV.
TABLE 2
Distribution of LAPTM4B genotype in hepatocellular carcinoma
patients and normal population
N (%)
Hepatocellular
Control B
carcinoma group
(n = 209)
(n = 57)
P Value
LAPTM4B genotype
*1/*1
96 (45.93)
17 (29.82)
0.029 a
*1/*2
90 (43.06)
25 (43.86)
0.914
*2/*2
23 (11.01)
15 (26.32)
0.003 b
Frequency of alleles
*1
0.6746
0.5175
*2
0.3254
0.4825
a OR: 0.500, 95% CI: 0.267-0.939;
b OR: 2.888, 95% CI: 1.390-6.003 (OR risk suffering HCC, and 95% CI is confidence interval)
TABLE 3
Clinical data of the hepatocellular carcinoma patients used
in LAPTM4B genotype classification
LAPTM4B Genotype
*1/*1
*1/*2
*2/*2
P Value
Total number
17
25
15
NS
Males
14
24
12
Females
3
1
3
Cancer Grade
G1
0
2
0
NS
G2
1
4
8
G3
7
7
4
G4
9
12
3
Cancer stage
I
0
0
0
NS
II
5
8
5
III
4
7
3
IV
8
10
7
HBV Infection
Negative
1
4
4
NS
Positive
13
16
10
No diagnosis
3
5
1
NS: No significant difference
Example 11
Frequencies of Genotype and Allele in Patients with Esophagus Carcinoma
To study if the LAPTM4B genotype is related to the susceptibility of developing other cancers, the genomic DNA from blood of 116 normal people and 109 patients with esophagus carcinoma from the same location were analyzed. As shown in Table 4, LAPTM4B genotype of patients with esophagus carcinoma is no significant different from control group of the normal population. LAPTM4B alleles are not related with the susceptibility of developing esophagus cancer.
TABLE 4
Distributions of LAPTM4B genotypes of patients with
esophagus carcinoma and normal population
N (%)
Control
Control
Esophagus
group B
group S
carcinoma
(n = 209)
(n = 116)
(n = 109)
P Value
LAPTM4B genotype
*1/*1
96 (45.93)
52 (44.83)
49 (44.95)
>0.05
*1/*2
90 (43.06)
49 (42.24)
48 (44.04)
>0.05
*2/*2
23 (11.01)
15 (12.93)
12 (11.01)
>0.05
Allele frequency
*1
0.6746
0.6595
0.6697
*2
0.3254
0.3405
0.3303
Example 12
LAPTM4B-35 Expression in Some Epithelium Sourced Cancers
The relationship between the LAPTM4B-35 protein expression and other cancers was studied by an immunohistochemical method. The fixed specimens from esophagus cancer, breast cancer, lung cancer, stomach cancer, colon cancer, and rectal cancer positive tissues and the negative control noncancerous tissues were obtained from surgical excision and treated according to the following steps:
1. Specimen dewaxing by xylene
2. Katocromy with different concentrations of ethanol, 100%-95%-90%-80%-70%. H 2 O 2 was used to remove endogenous peroxidase
3. Antigen repairing by sodium citrate
4. PBS rinse twice
5. Normal goat serum blocking
6. Keep LAPTM4B-N 1-99 pAb at 37° C. for 1 hour
7. PBS rinse three times
8. Keep HRP labeled goat anti-rabbit antibody at 37° C. for 1 hour
9. PBS rinse three times
10. Develop color by DAB
11. Nuclear retaining with hematoxylin
12. Ascending dehydration by ethanol at different concentrations (70%-80%-90%-95%-100%
13. Mounting
As shown in FIG. 11 , the 11 -A indicates a normal esophagus tissue (Negative), B is an esophagus cancer tissue (Negative), C is a normal breast tissue (Negative), D is the breast cancer tissue (Positive), E is a normal lung tissue (Negative), F is a lung cancer tissue (Positive), G is a normal stomach tissue (Negative), and H is a stomach cancer tissue (Positive). As can be seen from the figures, LAPTM4B was clearly expressed in lung cancer, stomach cancer, and breast cancer tissues, while it was not expressed clearly in esophagus cancer and large intestine cancer.
INDUSTRIAL APPLICATIONS
The proteins encoded by LAPTM4B gene in this invention could be possibly used as new markers in early diagnosis of some cancers. By using the widely applied ELISA method in clinical tests, and the prepared related testing reagent kits, the efficiency and the accuracy of the early diagnosis of cancers, especially the primary hepatocellular carcinoma, can be improved.
LAPTM4B gene can be used as target gene in the cancer treatment. Suppressing LAPTM4B-35 expression and promoting LAPTM4B-24 expression could inhibit the growth of hepatocellular carcinoma cells, reverse malignancy phenotype or delay its development. For example, the expression products of LAPTM4B gene, LAPTM4B-35 could be inhibited by the newly developed siRNA interference technology. Furthermore, LAPTM4B-BE-cDNA could be recombinated in the engineered virus expression vector and be used in antitumor gene therapy through an up-regulation of LAPTM4B-24 expression. LAPTM4B-35 protein could also be used as a new target for pharmaceutical treatment. Since LAPTM4B-35 protein can function as an assembling platform for complex of cell signal transduction molecules, and it contains a number of binding sites for signal molecules, there is a great potential to develop various new medicines with LAPTM4B protein as targets. Moreover, this invention has initially demonstrated that LAPTM4B-EC2-pAb antibody can inhibit tumor cell proliferation and block its signal transduction. Based on the discovery in this invention, further studies can be pursued on the possibility of using antibody to inhibit hepatocellular carcinoma and some other cancer development. After a better understanding on the effect, a humanized soluble single chain antibody could be developed for clinical treatment on HCC patients. Peptide vaccines could also be developed. If the vaccines can be successfully made, it will not only help cure hepatocellular carcinoma and some other cancer, but also prevent cancerogenesis in the high risk population. In summary, many new anticancer approaches can be developed based on the embodiments of this invention. As important supplements for treatments of hepatocellular carcinoma and other cancers, this invention will help increase the cure rates of hepatocellular carcinoma and other cancers. This project would generate a significantly great impact on human society.
In specific embodiments, LAPTM4B genotype of genomice DNA is genotyped. The relationship of various genotypes with the susceptibility to hepatocellular carcinoma as well as with other cancers s is investigated. It is discovered that one of the genotypes, LAPTM4B*2/*2, is correlated closely to hepatocellular carcinoma susceptibility. As a result, it provides a new and accurate criterion for screening people who are susceptible to primary hepatocellular carcinoma in the high risk population. It is of important significance to the assessment and prevention of high risk population from developing hepatocellular carcinoma.
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The invention discloses a human cancer-related gene, LAPTM4B, its encoded products and their applications thereof. This human cancer-related gene provided by this invention comprises one of the following nucleotide sequences: (1) SEQ ID No: 1, SEQ ID No: 2, SEQ ID No: 3, SEQ ID No: 6, or SEQ ID No: 8 in the sequence listings; (2) Polynucleotides that encode the protein sequences of SEQ ID No: 4, SEQ ID No: 5, or SEQ ID No: 7 in the sequence listings; (3) DNA sequences having above 90% homology with the DNA sequences specified by SEQ ID No: 1, SEQ ID No: 2, SEQ ID No: 3, SEQ ID No: 6, or SEQ ID No: 8 in the sequence listings, and these DNA sequences encode the proteins with the same or similar functions. This invention enables the developments of new anti-cancer approaches and new anti-cancer medicines. It would create a significant impact on human society.
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CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority of European Patent Application No. EP 13 002 883.0, filed Jun. 5, 2013, the content of which is incorporated herein in its entirety.
FIELD OF THE INVENTION
The invention relates to a seal profile, having a hollow space, of a door seal of a doorway in a vehicle for public passenger transportation, more specifically of a high-speed train, the seal profile having at least one connecting member to be received by the coachwork and/or the door of the vehicle.
BACKGROUND OF THE INVENTION
A door seal for a high-speed rail vehicle is sufficiently known from the prior art. Such seals are highly stressed when used in doors of high-speed trains because the doors move with a considerable force against the seals in the door opening, thus subjecting the seals to a strong deformation. This is necessary to prevent the pressure surges, which occur when the high-speed train is moving and which act against the outer shell of the train, e.g. when two trains meet or when a train enters a tunnel, from entering into the interior of the vehicle.
US2009/243142 A1 discloses a seal with a connecting member, the connecting member serving for example for fixation on the coachwork of a vehicle. The connecting member has a support made of metal with a U-shaped cross-section, the support having several slots disposed in a row transversely to the longitudinal axis. The support is coated with an elastomer. The slots in the support serve to adapt the connecting member to the shape of the coachwork. The seal, which is disposed on the connecting member, has a hollow space and consists apparently of an elastomer.
Up to now seals with a complex cross-section were manufactured by vulcanisation in a mould. This is extremely complicated, particularly considering that a multitude of doors of different sizes must be equipped with such seals, wherein at least one moulding tool needs to be provided for each seal profile of each door type. This means that the expense required for providing the appropriate moulding tools, but also the manufacturing effort itself, are enormous as a consequence of job production in a mould.
SUMMARY OF THE INVENTION
The problem underlying the invention therefore consists in solving this problem. The problem more specifically consists in being able to manufacture door seals, including with a complex cross-section, at a lower cost. In order to be able to manufacture such a seal of the type mentioned in the introduction at a lower cost, the invention provides that the seal has at least one reinforcing element coated with an elastomer, the reinforcing element having a lesser elasticity in the longitudinal direction of the seal than in the transverse direction. Thereby, it is achieved that such a seal with such a reinforcing element can be manufactured by extrusion. Up to now, it was assumed that seals with complex cross-sections with reinforcements were not producible by extrusion. The reason for this is that the reinforcing element folds during the extrusion in the extrusion tool. Since the reinforcing element is now more rigid in the longitudinal direction of the seal, i.e. in the extrusion direction, than in the transverse direction, the formation of such folds during the extrusion is avoided.
It has already been pointed out that the object of the invention is seals, more specifically with a complex form or contour. Such a complex seal is characterized in that the wall of the seal has a drawn-in area in the area of the sealing lip. In the drawn-in or vaulted state of the seal, the wall of the seal has a contour with a U-shaped cross-section in the area of the sealing lip.
Furthermore, it is more specifically provided that the reinforcing element has a plurality of more specifically oval or diamond-shaped openings extending in the longitudinal direction of the sealing profile. Regarding the arrangement of the oval or diamond-shaped openings, it is provided that several rows of such openings are provided, the openings of the individual rows being staggered relative to each other. More specifically thanks to these openings extending in the longitudinal direction of the profile, and here more specifically very narrow oval openings, a high stability of the reinforcement in the longitudinal direction, i.e. in the direction of extrusion, is achieved. In the transverse direction however, the reinforcing element is highly flexible, which entails another advantage, which is that by inflating such a seal in the mounted state, in order to increase the sealing force between the door on the one hand and the frame of the vehicle on the other hand, or also between two doors, the seal can go through a great volume change, which increases the seal effect. Stated another way, the reinforcing element allows the seal to inflate from a non-inflated to an inflated state and expand in the transverse direction thereby sealing while being stable and not expanding in the longitudinal direction. The consequence of this is that the seal no longer has to be squeezed as much as in the prior art, the consequence being that the seal is subjected to less wear.
In this respect, according to another feature of the invention, means for inflating the seal are provided on the seal, the means for inflating the seal being more specifically a valve.
The seal has at least one connecting member to be received by the coachwork or the door of the vehicle. It has already been pointed out that the seal can be disposed on the front side of the door as well as on the front side of the frame of the coachwork of the vehicle. According to another feature of the invention, the connecting member is designed in the manner of a rail and is preferably made of an elastomer, so that the seal can be extruded in one piece together with the connecting member. The connecting member itself has grooves extending in the longitudinal direction of the seal, in order to be able to insert this seal into the front side of the door and/or the front side of the frame on the coachwork side by clipping it in.
According to another feature, the seal has a sealing lip, which preferably protrudes outward on the front side, i.e. is oriented toward the front side of the door or the front side of the frame on the coachwork side, depending on the installation.
The sealing lip, which is preferably also made of an elastomer, is disposed preferably in the middle of the seal in a parallel direction to the door surface. The arrangement of the sealing lip as well as the arrangement of the connecting member on the seal is such that the reinforcing element protrudes at least into the sealing lip or the connecting member, in order to effect a stable connection between the reinforcing element coated with an elastomer and the sealing lip or the connecting member. From this it is clear that the seal consists of four elements, namely two lateral parts or two sidewalls, comprising the reinforcing element coated with an elastomer and the connecting member on the one front side of the seal profile and, on the opposite side, the sealing lip, which is also connected to the sidewalls of the seal.
When manufacturing a seal of the type described above by extrusion, it has turned out to be particularly advantageous, if a silicone rubber is used as an elastomer. The reason for this is that silicone has excellent sliding properties for extrusion, which makes it possible to maintain a low friction resistance during passage through the extrusion tool, the consequence being that the formation of folds in the reinforcing element is also substantially avoided.
In the following, the invention is exemplarily described in more detail based on the drawings. In the drawings:
BRIEF DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic of a vehicle for public passenger transportation with a door;
FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1 ;
FIG. 3 is a cross-sectional view taken along line in FIG. 2 ; and
FIG. 4 is a detailed lateral view of a seal according to FIG. 2 , wherein the door receiving the seal profile has been left out.
DETAILED DESCRIPTION OF THE INVENTION
The vehicle 1 has a door opening 3 with the door 5 in its coachwork 2 . The door 5 can be designed as a sliding plug door or as a pivoting door, for example.
The design of the seal can be gathered in detail by looking at FIGS. 2 to 4 . FIG. 2 shows the seal 10 in a sectional representation, the seal being received by the door 5 . It is noticeable that the seal 10 has a reinforcing element 14 in the area of both walls 12 , which is coated with an elastomer layer 15 , e.g. a silicone rubber. The elastomer coating can be carried out on both sides of the reinforcing element 14 or only on one side. On each side, the wall 12 ends in the sealing lip 16 and in the connecting member 18 , the connecting member 18 having grooves 20 on both sides in the area of the transition to the wall 12 extending in the longitudinal direction, which allows for a clip-on arrangement on the front side 6 of the door 5 or the coachwork 2 . An essential part of the design of the seal 10 is that the respective reinforcing element 14 in the area of the wall 12 protrudes on the one hand into the connecting member 18 and on the other hand into the sealing lip 16 , in order to effect a stable connection of the reinforcing element and thereby of the flanks on the connecting member 18 on the one hand and on the sealing lip 16 on the other hand. The reinforcing element itself, which is formed by a woven fabric or a warp-knitted fabric or a weft-knitted fabric for example, is advantageously equipped with the elastomer layer 15 on both sides. The configuration of the reinforcing element 14 can be seen in detail in FIG. 4 . The reinforcing element 14 has several superimposed rows of slim oval openings 24 that are elongated in the longitudinal direction of the seal, which cause the reinforcing element 14 to be substantially non-elastic in the longitudinal direction (arrow 30 ) but extremely elastic in the transverse direction (arrow 35 ). This is explained by the fact that the openings 24 with a slim oval form, which are shown in FIG. 4 , are able to bulge in the direction of the arrow 35 when a tension is exerted in that direction, in order to be able to provide the desired elasticity in that direction when the seal is inflated. The same correspondingly applies to diamond-shaped openings.
The design of the reinforcing element can also be such that a foil made of a plastic, e.g. a polyethylene or polypropylene is equipped with the slim oval openings described above e.g. by die cutting or punching.
The seal with a complex cross-sectional design according to FIG. 2 has a drawn-in area 17 in the area of the sealing lip 16 . This means that the area 17 a of the wall 12 , which receives the sealing lip 16 , is vaulted toward the area 17 b facing the wall 12 with the connecting member 18 , the hollow space of the seal profile being downsized in the process. This means that the profile has a contour with a U-shaped cross-section. It has already been pointed out that seals, more specifically with a complex shape or contour, are the object of the invention. To sum up, such a complex seal is characterized in that the wall of the seal has a drawn-in area in the area of the sealing lip. In this respect, the seal as a whole, in its drawn-in or vaulted state, has a contour with a U-shaped cross-section ( FIG. 2 ).
In this regard, in FIG. 4 , a schematic of a valve 26 is visible, by means of which the seal profile can be inflated. When the seal profile is inflated, the seal takes up a rectangular shape, wherein the sealing lip protrudes outwards. This means that due to the internal pressure, the seal 10 will be deformed in the direction of the orientation of the sealing lip 16 , i.e. in the direction of the arrow 40 . Thereby, the individual openings 24 in the reinforcing element 14 of the flanks 12 , which at first have a longitudinally extending oval shape, then more specifically take up a more round shape. In contrast, by creating a negative pressure, the profile can be contracted, i.e. brought into the shape according to FIG. 2 . Since the sealing lip does not protrude from the seal, there is no risk of damaging the sealing lip when the door is brought into its closed position.
LIST OF REFERENCE NUMBERS
1 vehicle
2 coachwork
3 doorway
5 door
6 front side of the door or the coachwork
10 seal
12 wall of the seal
14 reinforcing element
15 elastomer layer
16 sealing lip
17 drawn-in area
17 a area of the wall with the sealing lip
17 b area of the wall with the connecting member
18 connecting member
20 grooves on the connecting member
24 oval openings
26 valve in the seal profile
30 arrow
35 arrow
40 arrow
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A door seal for a doorway in a vehicle for public passenger transportation has at least one reinforcing element coated with an elastomer, the reinforcing element having a lesser elasticity in the longitudinal direction of the seal than in the transverse direction.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an improved apparatus and method useful to produce sodium citrate. More particularly; the invention is an apparatus and related method to electrodialytically treat an impure aqueous solution of citric acid to produce substantially pure sodium citrate.
2. Description of Related Art
A review of citric acid and its production is presented in Kirk-Othmer, Encyclopedia of Chemical Technology, Second Edition, Volume 5, pages 524 to 541, John Wiley and Sons, Inc. (1964). Citric acid also known as β-hydroxy- tricarboxylic acid or 2-hydroxy-1,2,3-propane tricarboxylic acid.
Citric acid is produced by mycological fermentation of carbohydrates. The fermentation process yields citric acid and the balance of the fermented solution which includes a variety of impurities. In order to separate the citric acid from the impurities the fermentation solutions are filtrated to remove the mycelia, followed by either precipitation of the calcium salt or direct crystallization on concentration of the filtrate. When citric acid is recovered by calcium salt precipitation, the quantity of citric acid in the filtrate after mycelium removal is determined and the amount of calcium hydroxide needed to neutralize the solution is calculated.
The calcium citrate is transferred to an acidification tank. The citrate is suspended in the wash water, from a previous calcium sulfate filtration, and concentrated sulfuric acid is added simultaneously to give a slight excess of sulfuric acid at the end of the batch. The calcium sulfate is filtered off and washed using a conventional industrial filter.
The dilute citric acid solution is purified by de-colorization and de-mineralization. The de-colorization step involves treating of the solution with activated carbon, followed by a polishing filtration. The sparkling clear solution is then passed successively through a cation exchange resin bed and an anion exchange bed.
The de-mineralized citric acid is evaporated in a circulating vacuum pan granulator or in a circulating evaporator-crystallizer. Where sodium citrate is the desired product the citric acid is reacted with sodium hydroxide to yield sodium citrate.
The fermentation products yield by-products which have had little commercial value. They consist of a filter cake obtained from purification of syrup used as raw material, the mycelium filter cake, the filtrate from calcium citrate filtration which contains residual sugars, and hydrated calcium sulfate. The calcium sulfate is of a quality suitable to use as an excipient in pharmacology. Ergosterol has been obtained commercially from the mycelium of the surface fermentation process.
Sodium salts of citric acid are commercially useful. Two sodium citrate hydrates include Na 3 C 6 H 5 O 7 .2H 2 O and Na 3 C 6 H 5 O 7 .51/2H 2 O. Sodium citrate is used in foods as a buffering agent in conjunction with citric acid and for accurate control of pH in the manufacture of jams, jellies and preserves. It is also used as a stabilizer and emulsifier in processed cheese Sodium citrate additionally has pharmaceutical applications.
Electrodialysis uses direct current as a means to cause the movement of ions in solutions. Electrodialysis processes are well known in the art and are typically carried out in a stack arrangement comprising a plurality of flat sheet membranes. The stack consists of electrodes (anode and cathode) at either end and a series of membranes and gaskets which are open in the middle to form a multiplicity of compartments separated by the membranes. Usually, a separate solution is supplied to the compartments containing the electrodes. Special membranes may be placed next to the electrode containing compartments in order to prevent mixing of the process streams with the electrode streams. The majority of the stack between the electrode compartments comprises a repeating series of units of different membranes with solution compartments between adjacent membranes. This repeating unit is called the unit cell, or simply, a cell. Solution is typically supplied to the compartments by internal manifolds formed as part of the gaskets or by a combination of internal and external manifolds. The stacks can include more than one type of unit cell. Streams may be fed from one stack to another in order to optimize process efficiency. Usually the change in composition of a stream after one pass through the stack is relatively small and the solutions can be recycled by being pumped to and from recycle tanks. Addition of fresh solution to and withdrawal of product from the recycle loop can be made either continuously or periodically in order to control the concentration of products in a desired range.
Treatment of aqueous salt streams by electrodialysis to form acid and/or base from the salt is known. The aqueous salt stream is fed to an electrodialytic water splitting apparatus which comprises an electrodialysis stack and a means for electrodialytically splitting water. A useful apparatus is disclosed in U.S. Pat. No. 4,740,281. A useful means to split water to hydrogen ions (H + ) and hydroxyl ions (OH - ) is a bipolar membrane such as disclosed in U.S. Pat. No. 4,766,161. The bipolar membrane is comprised of anion selective and cation selective layers of ion exchange material. In order for the membrane to function as a water splitter, the layers must be arranged so that the anion layer of each membrane faces the anode. A direct current passed through the membrane in this configuration will cause water splitting with hydroxyl ions being produced on the anode side and a corresponding number of hydrogen ions being produced on the cathode side of the membrane.
Electrodialytic water-splitting in a two-compartment cell has been disclosed, for example, in U.S. Pat. No. 4,391,680 relating to the generation of strongly acidified sodium chloride and aqueous sodium hydroxide from aqueous sodium chloride. U.S. Pat. No. 4,608,141 discloses a multi-chamber two-compartment electrodialytic water splitter and a method for using the same for basification of aqueous soluble salts. U.S. Pat. No. 4,536,269 disclose a multi-chamber two-compartment electrodialytic water splitter and a method for using the same for acidification of aqueous soluble salts. Three-compartment electrodialytic water splitters are disclosed to be comprised of alternating bipolar, anion and cation exchange membranes thereby forming alternating acid, salt and base compartments (B). U.S. Ser. No. 135,562 discloses three-compartment electrodialytic water splitters. U.S. Pat. No. 4,740,281 discloses the recovery of acids from materials comprising acid and salt using an electrodialysis apparatus to concentrate the acid followed by the use of an electrodialytic three-compartment water splitter to separate the acid from the salt.
SUMMARY OF THE INVENTION
The present invention relates to a method and an apparatus of electrodialytically treating an acid to produce a desired salt of the anion of the acid. A cation can be introduced into a solution via a cheap donor salt solution such as NaCl or KCl, without significantly altering or degrading the purity of the final product. The apparatus comprises a three-compartment cell, which comprises at least two adjacent anion selective membranes to accomplish a cation substitution reaction exploiting the differential selectives of the adjacent anion membranes employed.
In a practical application, the present invention relates to an improved method to produce sodium citrate of the type wherein carbohydrates are fermentated to produce an aqueous solution containing citric acid. The improvement comprises electrodialytically converting the aqueous citric acid solution to sodium citrate solution. The aqueous citric acid solution is simultaneously converted to sodium citrate which is purified and more concentrated.
The electrodialysis apparatus comprises at least one unit cell. In a preferred embodiment used to convert acid to salt, the unit cell comprises at least one water splitter means, preferably a bipolar membrane, to convert water to hydrogen ion (H+) and hydroxyl ion (OH-). There is a first anion selective membrane adjacent to the water splitter means. The first anion selective membrane is selective to a first anion having a negative valence of at least -1 and preferably from -1 to -3, such as citrate anion. There is a base compartment (B) between the first anion selective membrane and the water splitting means located to receive the hydroxyl ion from the water splitter means. There is a second anion selective membrane adjacent to the first anion selective membrane. The second anion selective membrane is selective to a second anion which is different than the first anion preferably having a negative valence of less than the valence to which the first anion membrane is selective. A typical and preferred second anion, when the first anion is a citrate anion, is a chloride anion. The second anion selective membrane is nonselective or substantially less selective, to the first anion, i.e., citrate anion. There is a salt compartment (S) between the first and second anion selective membranes and an acid compartment (A) adjacent to the salt compartment (S). The salt compartment (S) is fed with the cation of donor solution, i.e., NaCl, from an outside source. It is in this salt compartment (S) that the desired cation (Na + ) is substituted and retained. The acid compartment (A) is adjacent to and disposed to receive hydrogen ion (H + ) from the water splitting means serially aligned with the second anion membrane of the unit cell. The first anion selective membrane is a "loose" anion membrane while the second anion selective membrane is a "tight" anion selective membrane relative to the first anion selective membrane.
The present invention includes a method of operation of the above recited apparatus to generate salt comprising the donor cation and the anion from an aqueous acid solution. In accordance with the method an aqueous solution is fed to the base compartment (B), an aqueous salt stream to the salt compartment (S), and an aqueous stream optionally comprising acid to the acid compartment (A). An electrical potential is created across the cell to cause the introduction of hydroxyl ion into the base compartment (B) and hydrogen ion into the acid compartment (A) from the water splitting means. Acid anions are transported from the base compartment (B) to the salt compartment (S). Salt anions are transported from the salt compartment (S) to the acid compartment (A). Acid depleted aqueous stream is removed from the base compartment (B). Similarly, the salt of an acid anion and a donor cation is removed from the salt compartment (S), and acid of the salt anion is removed from the acid compartment (A).
The method can generate substantially pure, more concentrated sodium citrate from an aqueous citric acid broth solution containing sugars, mycelium, and suspended solids using the above recited electrodialysis apparatus. An aqueous salt solution comprising citric acid (a first anion containing acid) from the fermentation system, downstream of the microfilter, is fed to the base compartment (B). An aqueous stream comprising sodium chloride or other suitable salt is fed into the salt compartment (S). An aqueous stream optionally comprising acid is fed to the acid compartment (A). A sufficient electrical potential is applied across the unit cells to cause the introduction of hydroxyl into the base compartment (B) and hydrogen ion into the acid compartment (A) from the means for splitting water. Citrate anion is transported from the base compartment (B) across the first anion selective means to the salt compartment (S) and chloride anion is transported across the second anion selective means from the salt compartment (S) to the acid compartment (A). Depleted citric acid aqueous stream is recovered from the base compartment (B). Substantially pure sodium citrate is recovered from the salt compartment (S) and substantially pure hydrochloric acid is recovered from the acid compartment (A).
The present invention thereby results in an improved process for obtaining purified sodium citrate directly from a substantially contaminated raw citric acid broth. It eliminates many intermediate steps for treating the citric acid broth to separate citric acid and convert it to sodium citrate as disclosed in the prior art. For example, in the prior art, sodium citrate was formed by contacting purified citric acid with sodium hydroxide. In accordance with the present invention the sodium is supplied by a safe, cheap, easy to handle, sodium chloride salt.
Additionally, the present invention is an improved method and apparatus for treating any acid stream to convert it into the salt of the anion by treating it with another salt, thereby avoiding the formation of salt by the direct chemical contacting of the acid and the base.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic drawing of an electrodialysis apparatus of the present invention.
FIG. 2 is a flow diagram illustrating a preferred process of the present invention to produce sodium citrate.
Corresponding elements in FIGS. 1 and 2 have the same reference characters, unless indicated otherwise. In the Figures, ion transport is indicated by a solid arrow.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be understood by those skilled in the art by reference to the accompanying Figures. FIG. 1 is a schematic drawing of an electrodialysis apparatus of the present invention. The electrodialytic water splitter shown in FIG. 1 is useful to convert an aqueous solution of citric acid to sodium citrate.
The water splitter comprises, in series, an anode 10 (e.g., a platinum or nickel anode); an anolyte compartment 14; repeating in series of acid (A); salt (S); and base (B) compartments; a catholyte compartment 16; and a cathode 12 (e.g., a platinum cathode). The acid, salt and base compartments (B) of the water splitter illustrated in FIG. 1 are defined by a plurality of serially arranged membranes as follows: a bipolar membrane 11b, a first anion selective membrane 11a, and a second anion selective membrane 11a'. Although FIG. 1 shows four serially arranged compartments, the electrodialytic water splitter is defined by a plurality of unit cells, each unit cell (UC) comprising a bipolar membrane (or equivalent structure capable of splitting water into hydrogen and hydroxyl ions), a first anion membrane, and a second anion membrane. The first anion selective membrane 11a adjacent to the water splitter means 11b is selective to citrate anions. The first anion selective membrane 11a is also known as a loose anion membrane in that it has low resistance to anion permeation. There is a base compartment (B) between the first anion selective membrane 11a and water splitter means 11b located to receive OH - from the water splitter means.
The second anion selective membrane 11a' is adjacent to the first anion selective membrane 11a. The second anion selective membrane 11a', also called a tight membrane, is selective to chloride anions and nonselective to citrate anions. There is a salt compartment (S) between the first and second anion selective membranes and an acid compartment (A) on the opposite side of the second anion membrane 11a' from the salt compartment (S). The acid compartment (A) is adjacent to and disposed to receive H + from a water splitting means which is serially aligned with the second anion membrane 11a' of the unit cell.
The anolyte and catholyte compartments typically contain a base, salt, or acid solution (e.g., NaOH, KOH, Na 2 SO 4 , or H 2 SO 4 ), the acid (A) and base (B) compartments initially contain a liquid comprising water, added via lines 13 and 17, respectively. Salt (S) compartment initially contains a salt solution, comprising a salt MX of a cation (M + ) and an anion, preferably NaCl added via line 19.
An electrical potential is applied between the electrodes 10 and 12 causing the citrate anions to pass through first anion membrane 11a from the base compartment (B) to the salt compartment (S) leaving behind the sugars, carbohydrates, mycelium and other contaminants such as Ca ++ , Mg ++ ions. Anions such as SO 4 = and Cl - initially contained in the broth will also be transported. The chloride anion, (as well as other anion contaminants present from the broth SO 4 = , pass through the second anion membrane 11a' to the acid compartment (A). The citrate anions and sodium cations remain in the salt compartment (S) as an aqueous sodium citrate solution. Hydrogen ions (H + ) are supplied to the acid compartment (A) via the function of the bipolar membrane 11b'. The combination of the hydrogen ions with the chloride anions yields hydrochloric acid in acid compartment (A) believed to be suitable for ion exchange regeneration. Hydroxyl ions (OH - ) generated at the bipolar membrane 11b pass into the base compartment (B).
Typically, the fermentation broth containing the citric acid also contains a variety of other anions and cations. These cations (Mg ++ , Ca ++ ) substantially remain in the base compartment (B) and are removed as part of the depleted base solution. Total neutrality results from the hydroxyl ions formed at the bipolar membrane.
The various anions other than citrate anions are represented by the designation (X - ) which refers not only to monovalent anions but also to divalent anions, such as sulfates, and mixtures thereof with the requirement that they can pass through the second tighter anion selective membrane leaving the citrate anions behind in the salt compartment (S). Because the salt compartment (S) is bounded by anion membranes the sodium cation remains there resulting in the formation of sodium citrate of increased concentration.
Useful bipolar membranes comprise a cation layer (+) and an anion layer (-). The cation layer permits the cations to pass through and the anion layer permits anions to pass through. The cation layer is a barrier to anions and the anion layer is a barrier to cations. In the stack of the present invention the anions layers face the anode and the cation layers face the cathode. Useful cation membranes permit cations to pass through and are a barrier to anions, and similarly useful anion membranes permit anions to pass through and are a barrier to cations.
Examples of bipolar membranes which are particularly useful include those described in U.S. Pat. No. 2,829,095 to Oda, et al. (which has reference to water splitting generally), in U.S. Pat. No. 4,024,043 (which describes a single film bipolar membrane), and in U.S. Pat. No. 4,116,889 (which describes a cast bipolar membrane and is most preferred) and U.S. Pat. No. 4,082,835. However, any means capable of splitting water into hydrogen and hydroxyl ions may be used; for example, spaced apart anion and cation membranes having water disposed therebetween.
Useful anion membranes include strongly, mildly, or weakly basic anion membranes. Commercially available anion membranes include membranes from Ionics, Inc., Watertown, Mass. (sold as Ionics 204-UZL-386 anion membrane), or from Asahi Glass Co. (sold under the trade name Selemion® AMV AAV, ASV anion permselective membranes), or from RAI Corporation, Hauppauge, Long Island, N.Y. or Asahi Glass or Tokuyama Soda (ACM).
For the purposes of the present invention the first anion selective membrane can be considered to be a "loose" membrane relative to the second anion selective membrane which is considered a "tight" membrane. The loose membrane permits the transport or migration across it of a greater variety of anions than the tight membrane. Preferably, the loose membranes permits the transport of anions having a valence of from -1 to -3, while the tight anion membrane permits transport of anions having a valence of only -1 across it. All of the anions in the base compartment (B) can transport again across the loose membrane 11a while only anions having a valence of -1 can transport from the salt compartment (S) across tight membrane 11a' into the acid compartment (A). The electrodialytic cell can be used to selectively form a salt of a higher valence anion in the salt compartment (S) and a lower valence anion in the acid compartment (A). This is particularly useful when trying to make sodium citrate from citric acid. This apparatus enables the donor cation sodium to be supplied by a relatively inexpensive sodium chloride rather than a more difficult to handle and expensive sodium hydroxide.
Useful loose and tight anion membranes are low electrical resistance type membranes. Resistance depends on parameters such as composition and thickness. For equal thickness a tight membrane typically has a higher resistance than a loose membrane. Loose membranes usually absorb more water, typically greater than 40 percent water by weight than tight membranes which typically absorb less than 40 percent by weight of water.
Loose anion membranes usually have a strong base associated with them to permit the anions to be easily attracted and moved through the membrane. Such membranes, for example, have positive charges supplied by quarternary amines. Resistances in 0.5 molar sodium chloride solution at 25° C. are typically less than 8 ohm centimeters square and preferably in the range of from 2 to 4 ohm centimeters square. Typical capacities of loose membranes are from 1 to 2 millieq/gram. Thicknesses of such membranes can vary and are typically from 0.05 to 2.0 millimeters and preferably, from 0.05 to 0.3 millimeters thick.
Tight membranes are usually weak base anion membranes. Examples of useful weak base anion membranes are Asahi's ASR, AAV and ACM (also made by Tokuyama Soda). Such bases can be tertiary amines and the resistance in 0.5 molar hydrochloric acid 25° C. is typically between 3 and 8 ohm centimeters square. Such membranes typically have thicknesses of from 0.1 to 0.2 millimeters and preferably, between 0.11 and 0.14 millimeters.
The sodium chloride salt feed can be at concentrations up to saturation, preferably, from 0.1 molar to saturation concentration, and are typically 0.5 molar or more. The citric acid feed stream can contain from 3 to 5, preferably 5 to 25 and more preferably 10 to 25 weight percent citric acid. The sodium citrate product stream will be at concentrations corresponding to the NaCl and citric acid feed streams. Preferably, the concentration of sodium citrate in the product is from 10 to 50, preferably 20 to 50, and more preferably 35 to 50 weight percent. The concentration of the hydrochloric acid in the acid compartment (A) product stream is from 2 to 25, preferably 2 to 15, and more preferably 5 to 15 weight percent.
As illustrated in FIG. 1, the acid product from compartment (A) is removed via line 15, the depleted citric acid feed stream is removed from base compartment (B) removed via line 18, and the sodium citrate salt solution from salt compartment (S) is removed via line 20. The electrodialytic water splitter can be operated in a batch mode, a continuous mode, or variations thereof. Product solutions or portions thereof may be recycled for further concentration.
Useful operating temperatures of from 0° C. to 100° C. are possible if the stability of the membranes and the solubility of the solution constituents permit. Generally, membrane life is longer at lower temperatures and power consumption will be lower at higher temperatures. Preferred operating temperatures are between 25° and 60° C., and more preferably, from 35° to 50° C.
The current passed through the water splitter is direct current of a voltage dictated by design and performance characteristics readily apparent to the skilled artisan and/or determined by routine experimentation. Current densities between 25 and 300 amps per square foot (between 28 and 330 milliamps per square centimeter) are preferred; and current densities between 50 and 150 amps per square foot (between 55 and 165 milliamps per square centimeter) are more preferred. Higher or lower current densities can be used for certain specific applications.
The present invention includes an improved method and related apparatus to electrodialytically make and convert citric acid to sodium citrate with improved purity and higher concentration.
The present invention includes an improved method to produce more concentrated sodium citrate of the type wherein carbohydrates are fermented to produce an aqueous solution containing citric acid. The improvement comprises electrodialytically converting the aqueous citric acid solution to sodium citrate solution. The electrodialytic process uses the apparatus and method as recited above. In addition to forming sodium citrate the citric acid broth is simultaneously converted to a purified sodium citrate in the electrodialysis unit. Unwanted cations are removed with the depleted stream 18 from the base compartment (B) and the chloride anions and other undesirable anions are removed with the acid stream 15 which is predominantly hydrochloric acid.
The method of producing sodium citrate by fermenting carbohydrates is well known as indicated in the Background of the Invention and described in Kirk-Othmer, supra, as well as Fong, Fermentation Processes, Report No. 95, Stanford Research Institute, pages 35-87 (April, 1975). Briefly, it is well known to produce citric acid by submerged-culture fermentation. Citric acid is produced by the aerobic fermentation of molasses with ASPERGILLUS NIGER or other yeast, mold or bacteria. Citric acid is an intermediate metabolic product of oxidative dissimulation of sugar and is produced through the formation of pyruvic acid. The proposed mechanism for the production of citric acid is known as the Krebs cycle. The Krebs cycle is broken at a point where citric acid is formed and destruction of citric acid must be minimized or stopped. This is done by properly regulating the pH and adding the specific enzyme inhibitors to the medium of both. Furthermore, the destruction can be stopped if the concentration of metallic co-factors is limited by using complexing or precipitating agents such as ferrocyanide or other decationizing medium. When using ASPERGILLUS NIGER, the conversion of glucose to citric acid is illustrated at Fong, page 41, supra. Reference is made to fermenter 50 in FIG. 2 which represents a typical fermenting means known in the art.
Citric acid can be produced by fermentation using the surface as well as to submerged culture processes. In either process, the fermentation is carried out in dilute, aqueous carbohydrate solutions containing the necessary nutrients and additives with a strain of ASPERGILLUS NIGER at about 77°-90° F. (25°-32° C.) under aeration. Presently, industry prefers the use of submerged culture processes. Other processes which are not as widely commercially used include semi-solid methods which involve the steps of sugar solution impregnated with sugar cane or beet pulp, sponge, or other solid carriers. The mass is sterilized in an inoculator to initiate the fermentation. The product is recovered from the carrier by washing, compression or other means. In another method, hydrocarbons (mainly N-paraffins) were mentioned as possible carbon sources for commercial citric acid fermentation. The fermentation step is therefore well known and widely used. It results in an aqueous "broth" which contains in solution citric acid as well as a variety of residual acids, enzymes, carbohydrates and microorganism by-products and products. The broth is typically at the temperature of the fermentation process which, as indicated, is from about 25 ° to 35° C.
The carbohydrates used in commercial citric acid fermentation include the technically purified cane or beet sugars including the various molasses. Other carbohydrates can include beet molasses, dextrose, which is hydrolized from corn starch, as well as high test molasses. Also useful are glucose or refined sucrose, as well as the less expensive black strap molasses, which usually requires purification for good citric acid yield. It is reported that high metallic ion concentrations and high total ash content in the carbohydrate generally decreases citric acid yield. One of the common chemicals used to treat commercial cane or beet molasses is therocyanide, such as potassium therocyanide.
Although high metallic ion concentrations in the molasses may be detrimental to citric acid yield, certain amounts of inorganic salts containing magnesium, nitrogen, phosphorous, potassium and sulfur, as well as traces of iron and magnesium and zinc are essential for the fermentation. The medium composition reported to give excellent microorganism growth may not give the best yield of metabolic products, and materials used up in the growing process will not be available in the metabolic process. The correct medium recipe promotes a sub-normal growth of the microorganism, leading to the formation of mycelium mats with no or very slight sporulation which favors metabolic product formation. A salt concentration which is too high can cause mycelia growth and sporulation and possibly also cause oxalic acid formation, both of which decreases citric acid yield. A salt concentration that is too low can deprive the necessary nutrients needed for the microorganism to grow and metabolize. Because data are obtained under different operating conditions with various microorganisms, discrepancies have been reported on the effects of various metallic ions and salts. One optimal set of ion concentrations for synthetic medium used in the shake flash reported by Fong contained less than one gram per liter of potassium dihydrogen phosphate; less than 2.5 grams per liter of magnesium sulfite, heptahydrates; about 1 milligram per liter of iron and about 2.5 grams per liter of ammonium nitrate. Additionally, adding a small amount of methanol or ethanol to the fermentation medium increases the citric acid yield and submerged culture formation using a variety of hydrocarbons. Nitrogen sources typically required for the fermentation is generally added in the medium in the form of ammonium salts (e.g., nitrate), aqueous ammonia or urea. The carbohydrate is diluted with water to form a fermentation media containing about 10 to 25 weight percent of sugar. The higher concentrations are believed to help inhibit the formation of acids other than citric acid in submerged culture fermentation. Therefore, the broth can contain any of a variety of anions and cations. The process of the present invention results in a sodium citrate stream substantially free of these anions and cations.
The optimal temperature and pH depend largely on the strain of microorganisms that is used. With ASPERGILLUS NIGER, the temperature of the citric acid formation generally ranges from 25°-32° C. and the fermentation is typically kept at a relatively low pH. In submerged culture fermentation, for example, the pH should not be allowed to rise above 3.5 after three days of fermentation. Inorganic acids such as hydrochloric acid and sulfuric acid can be used to control the pH and calcium carbonate is often used as a pH buffer. In surface culture fermentation the most effective pH was about from 5 to 7.
Fermentation of citric acid by surface culture process is carried out in shallow aluminum or stainless pans or trays that are stacked together with a few inches of space between them and placed in a culturing chamber that is equipped with sterilization, air circulation and temperature and relative humidity control devices. The medium containing 10 to 20 weight percent sugar is sterilized after the pH is adjusted and then cooled. Each tray is filled to about 1.5 to 3 inches deep (38-76 millimeters), typically, by flowing the medium gravitationally down from the tops of the tray to below through overflow tubes. A typical tray is about 7 feet by 7 feet (2 meters by 2 meters) containing about 50 to 100 gallons (190-378 liters) of medium. The medium is inoculated with a strain of ASPERGILLUS NIGER and kept at from 28°-32° C. and a relative humidity of 44 to about 66%.
Using any of the above processes, results in an aqueous broth containing a hodgepodge of anions, cations, residual microbes, residual carbohydrates and sugars, and various impurities. Referring to FIG. 2 the composition is typically at about 25° C. (ranging from 15° to 45° C.). The composition is fed from fermentator 50 to a separation means, such as a filtration device or settling tank 52. The mycelium is separated from the crude acids solution and in the separating means 52 and removed via line 54. The crude citric acid aqueous solution is removed from the separating means 52 via line 56. The crude citric acid solution contains a variety of salts in the form of anions and cations in the aqueous solution included thereon is also the raw citric acid. The citric acid stream 56 is fed via line 17 to the electrodialytic water splitter 60. The raw citric acid stream 17 is fed to the base compartment (B) in the water splitter. As recited above, sodium chloride is fed to the salt compartment (S) and an aqueous stream, optionally containing an acid, is fed to the acid compartment (A). A sufficient electrical potential is applied across the cells to cause the introduction of hydroxyl ions into the base compartment (B) and hydrogen ions into the acid compartment (A) from the means for splitting water, preferably a bipolar membrane. Citrate anions first anion membrane 11a' to the salt compartment (S). The citrate ions are stopped at the second anion membrane 11a which is nonselective to the citrate ions. However, the second membrane is selective to the chloride ions in the salt compartment (S) which permeate through the second anion membrane 11a' into the acid compartment (A) where they react with the hydrogen ions from the adjacent cation layer of the bipolar membrane 11b to form hydrochloric acid. A depleted aqueous citric acid stream is removed from the base compartment (B) at about pH7. A sodium citrate aqueous stream, which is the product, is removed via line 20 from the salt compartment (S) and hydrochloric acid in an aqueous stream 15 is removed from the acid compartment (A).
In addition to forming sodium citrate, the use of a first loose anion membrane 11a and a second tight anion membrane 11a' also results in the purification of the sodium citrate stream. The first anion membrane prevents the uncharged species such as sugars, mycelium, as well as cations in the raw citric acid stream (e.g., Mg ++ , Ca ++ ) from leaving the base compartment (B). Such cations remain in the initial salt form and are withdrawn from the feed compartment. The hydroxyl ions from the adjacent anion layer of the adjacent bipolar membrane combine with remaining (H + ) ions to form water. The first loose membrane permits all of the anions in the raw citric acid stream 17 to pass through into the salt compartment (S). Typically, such anions include sulfate, chloride, as well as citrate anions. The second tight anion membrane 11a' is not substantially selective to the citrate ion which remains in the salt compartment (S). However, it is selective to the mono and divalent chloride ion and sulfate ion even trivalent anions, such as phosphate. The weak acid citrate anion does not pass through the second anion membrane. This results in the acid compartment (A) product stream 15 containing the acids of these various anions. The acid is predominantly hydrochloric acid due to the salt feed to the salt stream.
While exemplary embodiments of the invention have been described, the true scope of the invention is to be determined from the following claims.
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The present invention relates to a method and an apparatus of electodialytically treating an acid such as citric acid to produce a desired salt of the anion of the acid, such as sodium citrate. A cation can be introduced into a solution via a cheap donor salt solution such as NaCl or KCl, without significantly altering or degrading the purity of the final product. The apparatus comprises a three-compartment cell, which comprises at least two adjacent anion selective membranes to accomplish a cation substitution reaction exploiting the differential selectivities of the adjacent anion membranes employed.
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ORIGIN OF THE INVENTION
The invention described herein was made by an employee of the United States Government and may be manufactured and used by and for the Government for governmental purposes without the payment of any royalties thereon or therefor.
BACKGROUND OF THE INVENTION
The present invention generally relates to interferometers for determining the spatial direction of incoming radio waves referenced to an array of spaced antenna elements, and more particularly to an interferometer wherein all spatial frequencies generated by a signal and intercepted by the array are derived from a signal processing technique which utilizes real time convolution of functions in the spectral frequency domain. The signal processing technique is applied to an array of widely spaced pairs of antenna elements in order to form a single beam which is readily scannable. The system circumvents the shortcomings normally encountered in using interferometers, such as ambiguities which arise due to grating lobes and extreme vulnerability to interference due to the difficulty or inability for the interferometer to readily distinguish between two signals within the array system's field of view and within the receiver passband. The signal processing technique according to the invention differs from systems that sample spatial location, as practiced by collimating reflector systems and phased arrays, and from those systems which sample all spatial locations simultaneously, as practiced in adaptive array systems.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide a scannable beam-forming interferometer antenna array system which uses a signal processing technique that eliminates ambiguities and reduces the vulnerability to interference normally encountered in such systems.
It is another object of the invention to provide a scannable beam-forming interferometer antenna array system which uses a minimum number of antenna elements spaced in such a manner that the spatial frequencies of an array having a larger number of antenna elements can be derived without ambiguity.
According to the present invention, the scannable beam-forming interferometer antenna array system comprises a plurality of antenna elements spaced from one another by integral multiples of a fractional wavelength of the signal frequency, at least three pairs of antenna elements being selectable from the plurality of antenna elements. The spacings between the interferometer pairs are selected such that all desired spatial frequencies which are generated by a signal and intercepted by the array can be resolved. Signal processing begins by dividing the signals from each antenna element into two parts and, by using two coherent local oscillators, translating the antenna signals to first intermediate frequency signals. Selected pairs of first intermediate frequency signals are combined to form the interferometer pairs and obtain outputs having spatial frequencies determined by the spacing between the corresponding interferometer pairs. These spatial frequency signals are second intermediate frequency signals and are further mixed to produce the desired spatial frequencies at a third intermediate frequency. Summation of these third intermediate frequency signals yields spatial location with resolution and freedom from interference equal to that of a fully filled aperture of the same dimensions with similar element spacings.
The beam-forming interferometer array system according to the invention makes use of the spatial frequency/spatial location transform pair and involves the sampling and processing of signals in the spatial frequency domain. Each of the spatial frequencies resolved appear at an intermediate frequency level with all spatial phase information preserved; frequency and phase modulation associated with the arriving signal, however, are generally removed. The spatial frequencies are coherently summed to form a single beam and, thus, uniquely define the direction of the arriving signal. This summing process can be performed within the system or in space. The latter summation is accomplished by applying the processed spatial phase information to a fully filled transmit array, making the overall system a retro-directive array with a single beam returned in the direction of the signal source. This becomes a retro-directive system which requires no phase shifters, weighting circuits or scan controllers. In the former application, the beam formed by summing the spatial frequencies within the system may be steered by using intermediate frequency phase shifters where the number of phase shifters required would be one-half the number of radio frequency phase shifters required to scan an equivalent fully filled array at radio frequency. Alternatively, using the array phasing device described by R. J. Mailloux et al in "An Array Phasing Device Which Uses Only One Phase Shifter For Each Direction of Scan", AP Transactions, March 1968, pp. 258-260, beam steering can be accomplished by using only one phase shifter per direction of scan.
BRIEF DESCRIPTION OF THE DRAWING
The invention will be better understood from the following detailed description of a preferred embodiment which makes reference to the drawing in which the sole FIGURE is a block diagram of a four element interferometer array system according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
A linear array of four antenna elements 1, 2, 3 and 4 is illustrated in the drawing. This array provides six pairs of antenna elements. In other words, six different pairs of antenna elements can be selected from the linear array of four elements shown in the FIGURE. More generally, if the symbol ##EQU1## denotes the number of pairs of antenna elements which may be selected from an array n elements, then according to the invention ##EQU2## For any array of n antenna elements, the number of pairs can be computed from the following formula: ##EQU3## Using the above equation, the number of pairs in the illustrated embodiment are computed as follows: ##EQU4##
As shown in the FIGURE, the antenna elements 1,2,3 and 4 are relatively widely spaced. More specifically, antenna elements 1 and 2 are spaced 3λ/2, antenna elements 2 and 3 are spaced 10λ/2, and antenna elements 3 and 4 are spaced 2λ/2. In general, these spacings are selected such that all desired spatial frequencies which are generated by a signal intercepted by the array can be resolved. Spacings may be, for example, multiples of one-quarter wavelength or partial multiples of a wavelength. Arbitrarily, chosing antenna element 1 as being the reference, the incident signal ω s having a frequency or phase modulation φ m is illustrated as having a direction θ from the normal to the baseline established by the antenna element array. Thus, for the reference antenna element 1, the antenna signal is cos (ω s +φ m )t, but the antenna signal for antenna element 2 is cos [(ω s +φ m )t+Ψ 1 ]. In other words, the signal from antenna 2 appears to be modulated by Ψ 1 which is a spatial frequency determined by the spacing between antenna elements 1 and 2. Ψ 1 corresponds to the third spatial harmonic since antenna elements 1 and 2 are separated by 3λ/2. Similarly, as shown in the drawing, Ψ 2 is a spatial frequency determined by the spacing between antenna elements 2 and 3, Ψ 3 is a spatial frequency determined by the spacing between antenna elements 3 and 4, Ψ 4 is a spatial frequency determined by the spacing between antenna elements 1 and 3, and Ψ 5 is a spatial frequency determined by the spacing between antenna elements 2 and 4. Also, the following relationships are true:
Ψ 4 =Ψ 1 +Ψ 2
Ψ 5 =Ψ 2 +Ψ 3
Thus, the antenna signal for antenna element 3 is cos [(ω s +φ m )t+Ψ 4 ], and the signal for antenna element 4 is cos [(ω s +φ m )t+Ψ 4 +Ψ 3 ]. Ψ 4 corresponds to the thirteenth spatial harmonic since antenna elements 1 and 3 are separated by 13λ/2, and Ψ 4 +Ψ 3 corresponds to the fifteenth spatial harmonic since antenna elements 1 and 4 are separated by 15λ/2. In general there is a spatial harmonic for each λ/2, but in the antenna array shown in the drawing, some of these harmonics are missing. More specifically, in the preferred embodiment illustrated in the drawing, the odd spatial harmonics are used to determine spatial direction of the incoming signal, and those harmonics which are missing, such as the first, seventh, ninth and so forth, are derived by the signal processing technique to be described.
It will, of course, be understood that the signals from antenna elements 2, 3 and 4 appear to have the indicated spatial frequency modulations only by virtue of the selection of antenna element 1 as the reference and the selection of the specific interferometer pairs to be described hereinafter. In other words, selection of a different antenna element as the reference and a different selection of interferometer pairs will result in different apparent spatial frequency modulations of the antenna signals from each of the several antenna elements. Thus, it will be appreciated the specific number of antenna elements and spacings and choice of interferometer pairs as disclosed herein is by way of illustration only, and other different numbers and spacings of antenna elements and choice of interferometer pairs will produce different apparent spatial frequency modulations on each of the antenna element signals.
The signals from each antenna element are divided into two parts and translated to first intermediate frequency signals. More specifically, a first plurality of mixers and bandpass filters 5 to 12 are provided. Antenna element 1 is connected to mixers 5 and 6, antenna element 2 is connected to mixers 7 and 8, and so forth. Two coherent local oscillators 13 and 14 provide output signals to this first plurality of mixers 5 to 12. Specifically, local oscillator 13 is connected to mixers 5, 7, 9 and 11, while local oscillator 14 is connected to mixers 6, 8, 10 and 12. The local oscillator frequencies can be chosen to be either both above or both below the signal frequency when the incident modulation is to be removed. When the incident modulation is to be retained, the local oscillator frequencies are chosen such that one is above the signal frequency and the other is below the signal frequency. Assume, for example, that the signal frequency is 2.1 GHz and the frequency of local oscillator 13 is 1.66 GHz while the frequency of local oscillator 14 is 1.72 GHz. Under this assumption, the intermediate output frequency of mixers 5, 7, 9 and 11 is 440 MHz, and the intermediate output frequency from the mixers 6, 8, 10 and 12 is 380 MHz. The 440 MHz intermediate frequency will be designated as ω IF .sbsb.11 t and the intermediate frequency 380 MHz will be designated as ω.sub. IF.sbsb.12 t. The output signal frequencies of mixers 5 to 12 are shown in Table 1.
TABLE I______________________________________OUTPUTS OF FIRST MIXERSMixer No. Output______________________________________5 (ω.sub.IF.sbsb.11 + φ.sub.m)t6 (ω.sub.IF.sbsb.12 + φ.sub.m)t7 (ω.sub.IF.sbsb.11 + φ.sub.m)t + ψ.sub.18 (ω.sub.IF.sbsb.12 + φ.sub.m)t + ψ.sub.19 (ω.sub.IF.sbsb.11 + φ.sub.m)t + ψ.sub.410 (ω.sub.IF.sbsb.12 + φ.sub.m)t + ψ.sub.411 (ω.sub.IF.sbsb.11 + φ.sub.m)t + ψ.sub.4 + ψ.sub.312 (ω.sub.IF.sbsb.12 + φ.sub.m)t + ψ.sub.4 + ψ.sub. 3______________________________________
The outputs of mixers 5 to 12 are connected to terminals 15 to 22. These terminals are designed a1 to a8, respectively.
Having translated the signal from each antenna element to two different first intermediate frequency signals, the next step is to form interferometer pairs. The interferometer pairs are formed by mixing the first intermediate frequency signals from two different antenna elements in a plurality of second mixers and bandpass filters 23 to 30. The first intermediate frequency signals to be mixed in this second plurality of mixers are always of different frequencies so that the mixer outputs will be at the different frequency, in other words at a second intermediate frequency. In the example being considered, mixing first intermediate frequency signals of 440 MHz and 380 MHz results in a difference frequency of 60 MHz. The designations a1 to a8 for terminals 15 to 22 are used to indicate the inputs to the second plurality of mixers and bandpass filters 23 to 30. For example, as specifically illustrated in the drawing, the inputs to mixer 23 are connected to terminals a2 and a3. Following this convention, the inputs to mixer 24 are connected to terminals a1 and a4, and so forth. The 60 MHz second intermediate frequency will be designated ω IF .sbsb.2 t. Thus, outputs of mixers 23 to 30 are shown in Table 2.
Table 2______________________________________OUTPUTS OF SECOND MIXERSMixer No. Output______________________________________23 ω.sub.IF.sbsb.2 t + ψ.sub.124 ψ.sub.1 - ω.sub.IF.sbsb. 2 t25 ω.sub.IF.sbsb.2 t + ψ.sub.226 ψ.sub.2 - ω.sub.IF.sbsb.2 t27 ω.sub.IF.sbsb.2 t + ψ.sub.328 ψ.sub.3 - ω.sub.IF.sbsb.2 t29 ω.sub.IF.sbsb.2 t + ψ.sub.430 ω.sub.IF.sbsb.2 t + ψ.sub.5______________________________________
The interferometer pairs so formed appear at terminals 31 to 38, which are designated at b1 thru b8, respectively, again for purposes of indicating subsequent connections. It may be noted at this point that when the higher frequency first intermediate frequency signal from antenna element 2 is mixed with the lower first intermediate frequency signal from antenna element 1 in mixer 23, a normal function, cos (ω IF .sbsb.2 +Ψ 1 )t, is obtained. On the other hand, when that interferometer pair is formed using the other first intermediate frequency signals available in mixer 24, an inverted signal, cos (Ψ 1 -ω IF .sbsb.2)t, is obtained. Similarly, all interferometer pairs may be formed with either normal or inverted functions. It may also be noted that in each interferometer pair, the phase/frequency modulation argument is no longer present. If it is desired to recover the modulation, φ m , then an additional local oscillator is required.
Each interferometer pair generates grating lobes which are nothing more than a spatial frequency which is determined by the spacing between that pair. One may mix spatial frequencies to obtain still other spatial frequencies. Since the second intermediate frequencies signals are all the same frequency, i.e., 60 MHz, mixing two interferometer pairs produces a signal at a third intermediate frequency, e.g., at the sum of the two frequencies or 120 MHz. This is accomplished in a third plurality of mixers and bandpass filters 39 to 46. As before, the terminal designations b1 to b8 are used to designate the inputs to each of the mixers 39 to 46. For example, by mixing the inverted signal for interferometer pair composed of antenna elements 3 and 4 at terminal 36 (b6) with the normal function signal from the interferometer pair composed of antenna elements 1 and 2 at terminal 31 (b1), there is generated at the output of mixer 39 the difference between the two arguments (Ψ 1 -Ψ 3 ) at the third intermediate frequency. Since Ψ 1 is generated by an interferometer pair with a 3λ/2 spacing and Ψ 3 with a 2λ/2 spacing, the difference, i.e., (Ψ 1 -Ψ 3 ), is a function proportional to an interferometer pair with a spacing of λ/2. This is the fundamental or first spatial harmonic. Had signals from these interferometer pairs been chosen such that both functions were normal, the sum of the arguments (Ψ 3 +Ψ 1 ) would be obtained, producing the fifth spatial harmonic at the output of mixer 41. Similarly, other odd spatial harmonics are generated by utilizing sums or differences of the various interferometer pairs as shown in Table 3.
Table 3______________________________________DERIVATION OF SPATIAL HARMONICSSpatial Harmonic Interferometer Spacings Interferometer Pairs______________________________________ 1st 3 λ/2 - 2 λ/2 1,2 3,4 3rd 13 λ/2 - 10 λ/12 1,3 2,3 5th 3 λ/2 + 2 λ/2 1,2 3,4 7th 10 λ/2 - 3 λ/2 2,3 1,2 9th 12 λ/2 - 3 λ/2 2,4 1,211th 13 λ/2 - 2 λ/2 1,3 3,413th 10 λ/2 + 2,3λ/2 1,215th 13 λ/2 + 2 λ/2 1,3 3,4______________________________________
From Table 3, the outputs of mixers 39 to 46 at terminals 47 to 54 are shown in Table 4.
Table 4______________________________________OUTPUTS OF THIRD MIXERSMixer No. Output______________________________________39 ω.sub.IF.sbsb.3 t + ψ.sub.1 - ψ.sub.340 ω.sub.IF.sbsb.3 t + ψ.sub.4 - ψ.sub.241 ω.sub.IF.sbsb.3 t + ψ.sub.3 + ψ.sub.142 ω.sub.IF.sbsb.3 t + ψ.sub.2 - ψ.sub.143 ω.sub.IF.sbsb.3 t + ψ.sub.5 - ψ.sub.144 ω.sub.IF.sbsb.3 t + ψ.sub.4 - ψ.sub.345 ω.sub.IF.sbsb.3 t + ψ.sub.2 + ψ.sub.146 ω.sub.IF.sbsb.3 t + ψ.sub.4 + ψ.sub.______________________________________ 3
Retro-directivity is achieved by applying these arguments and their conjugates to a fully filled transmit array with half wavelength spacings. In other words, a radio frequency carrier is modulated by Ψ 1 and its conjugate, and these signals are applied to the inner most pair of the transmit array; Ψ 2 and its conjugate are applied to the next pair out from the center, and so forth. The eight odd harmonics derived from the four element interferometer array are thus positioned to phase a fully filled sixteen element transmit array.
Summation of these odd spatial harmonics within the system on the other hand, derived from the four element interferometer array, produces a resolution equal to that from a uniform sixteen element array with one-half wavelength spacings. Scanning of the beam is achieved simply by changing the relative phases of the various spatial harmonics (at 120 MHz) before summing, thereby requiring only one-half the number of phase shifters that would have been required at radio frequency to scan a fully filled sixteen element array. The output voltage from the system represents an aperture illumination function which was generated by a signal source from only one direction in space. The system, thereby, accomplishes a Fourier transform operation.
The invention has been described in terms of a specific illustrative preferred embodiment, and those skilled in the art will understand that the invention can be practiced in other and different ways. For example, a two dimentional array could be used instead of the illustrated linear array. Different numbers and spacings of antenna elements can be used, and even spatial harmonics can be generated instead of or in addition to the odd spatial harmonics to determine the direction of an incoming radio wave. An important point to be appreciated, however, is that the processing technique according to the invention provides a resolution and freedom from interference equal to that of a fully filled array without the ambiguities normally associated with interferometers.
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An antenna array comprising at least three interferometer pairs of antenna elements with selected spacings made to form a single beam which is readily scannable. All spatial frequencies generated by a signal and intercepted by the array are derived from a signal processing technique applied to the array. The array samples space in the spatial frequency domain while the signal processing technique utilizes real time convolution of functions in the spectral frequency domain. Summation of the appropriate spatial frequencies is equivalent to a Fourier transform operation, yielding the location of the signal source in space. Resolution and freedom from interference of the interferometer system is equal to that of a fully filled array of the same aperture size containing element spacings of one-half wavelength. An antenna array system comprising four antenna elements forming six interferometer pairs with a resolution equal to that of a sixteen element array with spacings of one-half wavelength is described, as well as other multiples of one-quarter wavelength or partial multiples of a wave length.
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ORIGIN OF THE INVENTION
The invention described herein was made in the performance of work under a NASA contract and is subject to the provisions of Section 305 of the National Aeronautics and Space Act of 1958, Public Law 83-568 (72 Stat. 435; 42 USC 2457).
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to solar photolysis of water to produce pure hydrogen and to various methods and apparatus for conducting such a process.
2. Description of the Prior Art
Self-sufficiency in energy is a stated national goal.
Most of the proposed means to achieve this goal are either environmentally unacceptable or are not feasible, especially those not depending on fossil fuel sources. Of the available alternatives, solar energy is the most abundant, inexhaustable single resource available. However, capturing and utilizing solar energy is not simple. Methods are being sought to convert solar energy to a concentrated, storable form of energy. A known method, photosynthesis, converts somewhat less than 1% of the sun's energy at the earth's surface to a solid fuel, i.e., plant materials, which when accumulated and transformed over geologic ages yielded fossil fuels. Current rates of use of these fossil fuels, and the particular geographic distribution and political control of major petroleum resources pose problems for nations that are net petroleum consumers. An alternate method yielding a simpler fuel, at a higher conversion, has long been desired.
Production of hydrogen by the solar photolysis of water would be an extremely desirable fuel, since it would be prepared in high purity, and the combustion product of hydrogen is water which is totally environmentally acceptable. However, it is widely believed that solar photolysis of water is not feasible, especially at quantum efficiency exceeding 1%. Douglas and Yost noted twenty four years ago in J. Chem. Phys. 17, 1345 (1949) and J. Chem. Phys. 18, 1687 (1950) that hydrogen was produced during photolysis of europium (II) solutions. Yields of hydrogen were not measured since their main interest was in europium oxidation. This sole reaction would not lead to a feasible process for photolyzing water since the europium ion would be continuously exhausted by stoichiometric reaction with water, therefore the process would be unduly expensive since the amount of hydrogen generated would not economically justify the cost of the europium reagent.
A cyclic photo-redox process having water and sunlight as reactants and hydrogen and oxygen and products has been disclosed in a patent application Ser. No. 658,132 filed Feb. 13, 1976, now issued on Aug. 30, 1977 as U.S. Pat. No. 4,045,315. That process utilized a soluble divalent europium photo-oxidation reagent in the hydrogen generation cycle and a complex series of steps in the dark in which a water-stable manganese oxychloride is utilized to regenerate the spent trivalent europium photo-oxidation reagent. The complexity renders the process less economic in the large scale harvesting of solar energy and the dark reaction requires use of dark panels or waiting for sunset to conduct the regeneration cycle of the process.
SUMMARY OF THE INVENTION
An improved process for the solar photolysis of water is provided in accordance with this invention. The process utilizes a photogenerated reductant capable of activation by ground level solar radiation during sunlight hours obviating the need to apply cover panels to the photoreduction reactor or to await dark periods for regeneration of the photo-oxidant reagent. The process of the invention produces improved yields of hydrogen and oxygen. The photoreductant is a single compound which reduces complexity and improves economics of the process.
The solar photolysis process of the invention utilizes transition metal ligand complexes in a photoexcited state for the reduction and regeneration of the spent photo-oxidant reagent. At least one of the photo-oxidant and the photo-reductant reagents are supported on an inert, particulate support. It is known that the complexes of transitions metals such as ruthenium with ligands such as bipyridine compounds in the photoexcited state can reduce trivalent europium and other ions. There has been no successful implementation of the reaction due to the well known competing reactions between the trivalent ruthenium ligand metal complex and the divalent europium compounds summarized as follows:
FORMATION REACTION
2h.sub.2 o + 2eu(+2) .sup.hν H.sub.2 + 20H.sup.- + 2Eu(+3)
REGENERATION REACTION
ruL.sub.3 (+2) .sup.hν *RuL.sub.3 (+2)
eu(+3) + *RuL.sub.3 (+2)→RuL.sub.3 (+3) + Eu(+2)
UNDESIRABLE SIDE REACTION OF RECYCLABLE PRODUCT
eu(+2) + RuL.sub.3 (+3)→Eu(+3) + RuL.sub.3 (+2)
undesirable reaction between metal complex and water
h.sub.2 o + 2ruL.sub.3 (+3)→1/2 O.sub.2 + 2H.sup.+ + 2RuL.sub.3 (+2)
undesirable reaction once oxygen is formed
eu(+2) + O.sub.2 →Eu(+3) + misc. products
The present invention conducts the regeneration reaction in a mode which prevents the two regeneration products from interacting undesirably and also prevents undesirable side reactions between either one of the regeneration products and other materials present such as water or oxygen. A simple batch regeneration process cannot and will not produce any significant recyclable amounts of regenerated photo-oxidant. In the present invention the efficiency of the regeneration reaction is promoted by separating in time and space the regeneration reaction from the photo-oxidation reaction and by use of flow systems, pH and wavelength control to separate the products of the photoexcited reductant reaction and the photo-oxidation reaction. The invention utilizes a particulate metal oxide support for either the photo-oxidant reagent, the photo-reductant reagent or both and may also utilize a hydrogen recombination catalyst in the photo-oxidation reaction reactor.
These and many other features and attendant advantages of the invention will become apparent as the invention becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of a first embodiment of the invention;
FIG. 2 is a schematic view of a second embodiment of the invention; and
FIG. 3 is a schematic view of a third embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The photo-oxidant reagent is a material which absorbs strongly in the solar range at ground level and in its excited state is capable of reducing water to produce hydrogen with a quantum efficiency exceeding 0.1%. Quantum efficiency is defined as the number of moles of hydrogen produced per mole of light absorbed. Suitable water soluble transition metal cations capable of such efficiency are, for example, Eu ++ , Cr ++ , V ++ and Ti ++ of which Eu ++ is preferred. The pH of solution is no greater than 5 and the preferred range being 4-5. A high concentration of from 0.5 to 5 M of any of the anions, Cl - , SO 4 -- , or PO 4 -- , is maintained by dissolving appropriate amounts of alkali metal salts of these anions in the photo-oxidation solution. Sodium chloride is the preferred anion source.
A heterogeneous hydrogen recombination catalyst is preferably immobilized in the photo-oxidation reactor. The catalyst is preferably in the form of non-porous beads or fibers on which is deposited by means well known to the art, highly dispersed metals such as Pt, Rh, Pd, Ir, Os, or Ni. The surface of the glass beads or fibers may be in the form received from normal manufacture or may be altered by initially etching the surface with dilute HF solution and then depositing on it by means well known to those skilled in the art, hydrogels of silica, alumina or selected combinations of these. The preferred combination is Pt on a glass surface treated with an alumina hydrogel so that the effective catalyst is platinum on an alumina surface. Obviously, hydrous aluminum in the form of beads or fibers may also be used instead of glass beads. However, it is important to note that the bead of fiber substrate must not be microporous; only the very surface (less than a 10 nm layer) may be a microporous layer having a high area. The metal concentration may be in the range of 0.5-0.05% by weight; the preferred range is 0.05-0.10% by weight.
The size of the beads or the porosity of the fiber mat is governed by the acid concentration. If the pH is 4, then the maximum of spacing between surfaces may not exceed 1.0 nm. Smaller spacing may be used and will occur in a bed of beads or a glass mat, but excessively small spacing will result in a long drainage time of the solution when it is transferred to the reductant after exposure to sunlight. Hence the spacing (e.g., bead size) will be selected to meet the above specification and yet have the bed drain in a reasonable time; that time being determined by reactor size in a manner well known to chemical engineering art.
An extended photoactive range may be obtained by the use of a photochromic glass, in which the composition of the beads or fiber is altered (at the time of manufacture) to make the glass photochromic. Additions of silver halides, copper halides, iron (ferric) halides, will provide glasses with photochromic properties.
In certain embodiments of the invention the europium photo-oxidation reagent is supported on particular inert metal oxide supports having pendant oxygen functional groups capable of associating with and binding the europium ion to the support during both the photo-oxidation reaction and during the reduction regeneration process. The amount of europium ion deposited on the support is determined by the quantum efficiency of the photo-oxidant.
Hydrogen production proceeds in the photo-oxidation reaction according to the following general reaction scheme:
M.sub.ox.sup.z+ + H.sub.2 O .sup.hν M.sub.ox.sup.(z+1)+ + H. + OH.sup.-
2h.→h.sub.2
where z is the valence of the photo-oxidation reagent, M ox . Pure hydrogen separates from the solution as a gas. The oxidized cation M ox .sup.(z+1)+ must be regenerated by reduction.
The photogenerated reductant utilized in the present invention is a luminescent excited state of *RuL 3 where L is a ligand such as a derivative of bipyridine or phenanthroline. Quenching of the emissions of polypyridineruthenium II complexes have been investigated by C. T. Lin et al (Jacs, 98:21 Oct. 1976) to determine the electron and energy transfer mechanisms. The complexes exhibit maximum absorbance around 450 nm and maximum emission around 600 nm and emission lifetimes of 0.001 to 5 microseconds. The absorption and emission spectra of representative complexes in water at 25° C is provided in the following table:
TABLE I__________________________________________________________________________Charge-Transfer of Absorption and Emission Spectra and Emission Lifetimes(τ.sub.0)of Polypyridineruthenium (II) Complexes in Water at 25° C Absorption Emission λmax. 10.sup.-4 ε λmax. nm τ.sub.0Complex nm M.sup.-1 cm.sup.-1 Uncorr.sup.a Corr μs.sup.c__________________________________________________________________________Ru[4,4'-(CH.sub.3).sub.2 bpy].sub.3 [ClO.sub.4 ].sub.2 . 3H.sub.2 (˜430).sup.b 460 1.43 628 633 0.33±0.01Ru[4,4'-(C.sub.6 H.sub.5).sub.2 bpy].sub.3 Cl.sub.2 . 6H.sub.2 O (˜445).sup.b 474 3.27 632 638(653).sup.b 0.67±0.03Ru[bpy].sub.3 Cl.sub.2 . 6H.sub.2 O (˜423).sup.b 452 1.46 607 613,627 0.60±0.02Ru[3,4,7,8-(CH.sub.3).sub.4 phen].sub.3 Cl.sub.2 . 6H.sub.2 O 438 2.45 597 605,625 1.39±0.10Ru[3,5,6,8-(CH.sub.3).sub.4 phen.sub.3 ][ClO.sub.4 ].sub.2 . 2H.sub.2 417,440 1.96,1.98 594 605,625 2.22±0.10.sup. dRu[4,7-(CH.sub.3).sub.2 phen].sub.3 Cl.sub.2 . 6H.sub.2 O 425,445 2.53,2.53 607 613,626 1.74±0.04Ru[5,6-(CH.sub.3).sub.2 phen].sub.3 Cl.sub.2 . 6H.sub.2 O 425,453 1.84,2.04 602 608,625 1.81±0.05Ru[4,7-(C.sub.6 H.sub.5).sub.2 phen].sub.3 Cl.sub.2 . 3H.sub.2) 460 2.95 610 613,627 4.68±0.19Ru[5-(CH.sub.3)phen].sub.3 Cl.sub.2 . 6H.sub.2 O 420,450 1.79,1.94 597 605,625 1.33±0.03Ru[5-(C.sub.6 H.sub.5)phen].sub.3 Cl.sub.2 . 5H.sub.2 O 420,448 2.32,2.46 595 605,625 1.29±0.02Ru[phen].sub.3 [ClO.sub.4 ].sub.2 . 3H.sub.2 O 421,447 1.83,1.90 593 605,625 0.92±0.10Ru[5-Cl(phen)].sub.3 [ClO.sub.4 ].sub.2 . 3H.sub.2 O 422,447 1.78,1.84 593 605,625 0.94±0.03Ru[5-Br(phen)].sub.3 Cl.sub.2 . 5H.sub.2 O 420,448 1.82,1.88 593 605,625 1.04±0.02Ru[5-NO.sub.2 phen].sub.3 I.sub.2 . 3H.sub.2 O 449 2.0 ˜595 ˜606 ≦5 × 10.sup.-3Ru[terpy].sub.2 [ClO.sub.4 ].sub.2 . 3H.sub.2 O 473 1.62 ˜610 ˜628 ≦5 × 10.sup.-3Ru[TPTZ].sub.2 [ClO.sub.4 ].sub.2 . 3H.sub.2 O 501 1.92 ˜600 ˜605 ≦5 × 10.sup.-3__________________________________________________________________________ .sup.a These maxima refer to values obtained in the "ratio mode". The quenching measurements were generally made at the emission maximum in the "energy mode". .sup.b Shoulder. .sup.c Average of five-six determinations with standard deviation. .sup.d Emission lifetime is 2.08±0.10 μs in 0.5 M sulfuric acid.
The 4,7--(CH 3 ) 2 phen, 5,6--(Ch 3 ) 2 phen, 5--(CH 3 )phen complexes show appreciable reaction with europium (III). The emission lifetimes are greatly increased by the introduction of phenyl groups in the 4,7 positions of the phenanthroline ring system. However, the lifetimes do not otherwise appear to be especially sensitive to substitution in the 4,7 positions, since the lifetimes of the 4,7 and 5,6 dimethyl derivatives are comparable. Also of interest is the result that introduction of a methyl group in the 4,4'positions of bipyridine decreases the emission lifetime of the complex, whereas the lifetime of the phenanthroline complex is increased by methyl substitution. By contrast, the emission lifetime of the bipyridine and the phenanthroline complexes are both increased by phenyl substitution.
A first embodiment of the invention utilizes a supported Europium(III)photo-oxidant reagent and a soluble photo-reductant regeneration reagent.
Referring now to FIG. 1, the photolytic hydrogen production system includes a photo-oxidation reactor 10 having a face 11 directed towards and transparent to solar radiation 14. The transparent panels utilized in the reactor must be transparent to the full ground level solar range, i.e. down to 290 nm. Suitable materials are fused silica, sapphire (Al 2 O 3 ), Vycor (high silica glass) and Pyrex (borosilicate glass), the latter being preferred.
The reactor 10 includes particulate photo-oxidation reagent 13 Eu(II) deposited on an alumina support and hydrogen recombination catalyst particles 15 in bead or fibrous form.
The reactor has an inlet, 18, connected to a manifold 25 containing a pump 26 and valve 20. The manifold 25 also connects through valve 22 to the outlet 20 to water supply tank 32. The process of the invention requires ultra pure water. The water may be purified by repeated distillation, reverse osmosis or ion exchange and filtering on activated carbon. Furthermore, the solution in the photo-oxidation reactor 10 must be free of oxygen. Gases may be eliminated from the water supply by means of a vacuum pump or by purging with an inert gas, suitably nitrogen, for example, by introducing nitrogen under pressure from tank 35 into inlet 34 when valve 36 is open and purging through vent 38 when valve 40 is open.
The pure, nitrogen purged water 37 is introduced into reactor 10, by opening valves 20 and 22, and by activating pump 26. Valve 22 is then closed.
Irradiation of the water in reactor with light at a wavelength of λ < 400nm, in presence of supported photo-oxidant reagent, Eu(+2) and recombination catalyst results in production of hydrogen according to the following reaction:
2H.sub.2 O + 2Eu(+2) .sup.λ<400nm 2Eu(+3) + H.sub.2 + OH.sup.-
hydrogen is collected in vessel 49 with valve 51 open. Upon completion of the hydrogen production cycle, the supported reagent is in the Eu(+3) state. A filter cover 41 passing light of λ > 450nm is disposed between the face 11 and the source 14 of incident solar radiation. The spent solution is drained from vessel 10 through outlet 44 by opening valve 46. A solution 48 of ruthenium trispyridyl chloride is then flowed over the supported Eu(+3) by means of pump 26 when valves 20 and 50 are open. The following three reactions occur.
RuL.sub.3 (+2) .sup.hν λ>450nm *RuL.sub.3 (+2)
eu(+3) + *RuL.sub.3 (+2)→Eu(+2) + RuL.sub.3 (+3)
h.sub.2 o + 2ruL.sub.3 (+3)→2H(+) + 1/2 O.sub.2 + 2RuL.sub.3 (+2)
the solution of reductant must remain flowing through the vessel 10 until complete regeneration to Eu(+2) has occurred since the oxygen produced would react with the regenerated Eu(+2). Oxygen can be recovered in recovery vessel 54 when valve 56 is open. Furthermore, due to the very short lifetime of about 0.85 microseconds of *RuL 3 (+2), surfaces of the particulate Eu(+3) must be close together (at least about 64nm). The required rapid flow to remove RuL 3 (+3) along with possible oxygen from the vicinity of the Eu(+2) can be provided by any conventional means, with attention to minimizing turbulence. However it may develop that certain highly turbulent systems involving high pressure drop may also be employed.
After complete regeneration, the reductant solution 48 is removed through outlet 44 and valve 46 closed. Valve 50 is closed, valve 22 opened and fresh water reintroduced into vessel 10. When filter panel 41 is removed, hydrogen production by photolysis again proceeds.
The system of FIG. 2 utilizes a supported photogenerated reductant and a soluble photo-oxidant. The system includes a photo-oxidation reactor vessel 200 and a reductant column 201. The vessel 200 contains hydrogen recombination catalyst particles 202. The reactor 200 has a panel 204 transparent to incident radiation 206 at a wavelength of <400nm. The column 201 contains particulate supported reductant RuL 3 205 such as the 4,4'-dicarboxy derivative of bipyridine bonded to the surface of alumina particles. The --COOH carboxy, and --N═ tertiary amine groups are both capable of associating, complexing or chelating with the alumina particles to form bonds capable of surviving the conditions of the process.
The process is initiated with a dilute Eu(+2) solution 208 present in the vessel 200. Hydrogen is liberated when incident solar radiation 206 photolyzes the water according to the following reaction:
2Eu(+2) + 2H.sub.2 O .sup.hνλ<400nm 2Eu(+3) + H.sub.2 + 2OH--
generated hydrogen is collected at outlet 203.
The strongly acidic spent solution 208 is then pumped by means of pump 210 into column 201 with valve 212 open and valve 214 closed. The walls 216 of the column 201 are either covered with a +450nm band pass filter or the walls are fabricated from a material passing the desired wavelengths. The incident solar radiation 206 will generate reductant according to the following reaction:
RuL.sub.3 (+2) .sup.hν λ>450nm *RuL.sub.3 (+2)
as the spent solution 208 flows over the reductant regeneration occurs as follows:
Eu(+3) + *RuL.sub.3 (+2)→RuL.sub.3 (+3) + Eu(+2)
Oxygen is evolved very slowly by RuL 3 (+3) from strongly acidic solutions. Therefore by slowly flowing the solution through the column 201, regenerated Eu(+2) can be conducted away from the fixed RuL 3 (+3). By utilizing a sufficiently lengthy column, substantially all of the Eu(+3) is regenerated. No lifetime limitation exists as to Eu(+2) and hence, spacing of the surfaces of the RuL 3 particles can be adjusted to provide an adequate flow rate at low pressure differentials. The regenerated photoxidant solution is recycled to reactor 200 through line 218 with valve 214 closed and valve 220 open.
The cycle is completed by a dark reaction to regenerate the RuL 3 (+3) and to generate oxygen. After recycle of the regenerated solution, valve 214 is closed, valve 237 is opened and water at pH 7 is pumped into column 201. A dark cover 232 is placed over the column. The following reaction proceeds.
H.sub.2 O + 2RuL.sub.3 (+3) .sup.dark 2RuL.sub.3 (+2) + 2H.sup.+ + 1/2 O.sub.2
oxygen is collected at 234. After complete regeneration the wash water is drained with valve 214 directed toward outlet 236.
In a further embodiment of the invention both the Eu(+3) photo-oxidant and *RuL 3 (+2) photo-reductant are bonded to the surface of a support such as particulate alumina. Control of the pH of the aqueous media is utilized to separate the production of hydrogen and oxygen according to the following reactions.
Reductant Activation
RuL.sub.3 (+2) .sup.pH<5 *RuL.sub.3 (+2)
hydrogen Formation
*RuL.sub.3 (+2) + Eu(+3) .sup.pH<5 RuL.sub.3 (+3) + Eu(+2)
2Eu(+2) + 2H.sub.2 O .sup.pH<5 2EU(+3) + H.sub.2 +OH.sup.-
the above-recited irradiation steps utilize light in the wavelength range of about 290 to 550 nm.
Regeneration Step ##EQU1##
Referring now to FIG. 3 the solar photolysis reactor 300 contains particles 302 on which is supported Eu(+3) ions and RuL 3 (+2) ions. The reactor 300 has a face 304 directed toward and transparent to solar radiation 306 in a wavelength band of from 290 to 550 nm.
When water 305 at low pH, suitably from 4 to 5, is pumped into reactor 300, the water is photolyzed to produce hydrogen recovered in vessel 308 when valve 310 is open while oxygen production is supported.
The low pH water can be made up by adding an acid to the feed delivered to inlet 312 or the water leaving outlet 314 can be concentrated by evaporation, suitably in solar evaporator 316 before being recycled to reactor inlet 312 by recycle line 318 containing pump 320.
During hydrogen production, the photogenated reductant will regenerate Eu(+3) to Eu(+2) until all of the reductant is oxidized to RuL 3 (+3).
At this stage, all of the media 307 is pumped into evaporation tank 316, water at pH 7 is pumped from supply 321 with valve 322 open and valve 324 closed and dark panel 326 is rotated over face 304. The regeneration step proceeds in the dark to production of oxygen which collects in vessel 328 when valve 330 is open.
Judicious pH control during the pH 5 -stages of the above process serves to minimize or prevent direct reduction of the supported RuL 3 (+3) by hydrogen as H or H 2 +, which represents a possible side reaction during regeneration-formation steps.
It is to be realized that only preferred embodiments of the invention have been described and that numerous substitutions, modifications and alterations are permissible without departing from the spirit and scope of the invention as defined in the following claims:
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A cyclic process for the solar photolysis of water includes a first stage in which water is reduced in the presence of a Eu +2 photo-oxidizable reagent producing hydrogen and spent oxidized Eu +3 reagent. The spent reagent (Eu +3 ) is reduced by means of a transition metal ligand complex reductant, *RuL +3 in a photoexcited state, such as a ruthenium pyridyl complex. Due to competing reactions between the photolysis and regeneration products, the photo-oxidation reaction must be separated from the regeneration in space and time by supporting the reagent and/or the reductant on solid supports and utilizing pH, wavelength and flow control to maximize hydrogen and oxygen production.
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FIELD OF THE INVENTION
This invention relates to a joint for joining a fuel tube to a fuel rail by means of a clip.
BACKGROUND AND SUMMARY OF THE INVENTION
With the advent of plastic fuel rails, new designs for attaching appurtenances to a fuel rail must be developed. One such appurtenance is a metal or plastic fuel tube, examples of such tubes in a fuel rail assembly being a fuel supply tube, a fuel return tube, and a fuel crossover tube. Although a number of designs for attaching plastic and metal tubes are known to the applicants, many are poorly suited for plastic fuel rail applications because they are too complex, too weak, too expensive or because their tolerances cannot be adequately controlled. It is believed that need exists for improvements for attachment designs for this application. It is toward fulfilling this need that the present invention is directed.
Accordingly, a primary object of the invention is to provide a functionally integrated attachment clip for attaching a fuel tube to a fuel rail, such clip possessing the attributes of low-cost and ease of attachment, and being capable of creating and reliably maintaining integrity of the joint against leaks, yet allowing the joint to be conveniently disconnected if an occasion requiring its disconnection ever arises. A joint embodying principles of the invention allows full 360 degree relative rotation of a fuel tube while keeping a fuel and pressure resistant seal.
The foregoing features, advantages, and benefits of the invention will be seen in the ensuing description and claims which are accompanied by drawings that disclose a presently preferred embodiment of the invention according to the best mode contemplated at this time for carrying out the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded perspective view of a representative joint embodying principles of the invention,
FIG. 2 is a perspective view of one component of the joint, to wit the clip, shown by itself on an enlarged scale from the view of FIG. 1, and with a portion of the clip having been broken away for illustrative purposes.
FIG. 3 is an assembled view of the joint from a different perspective from the view of FIG. 1, but on an enlarged scale and with portions broken away for illustrative purposes.
FIG. 4 is a transverse cross sectional view through the joint, taken in the direction of arrows 4--4 in FIG. 3.
FIG. 5 is a cross sectional view generally in the direction of arrows 5--5 in FIG. 4.
DESCRIPTION OF THE PREFERRED EMBODIMENT
A joint 10 serves to join one end of a fuel tube 12, shown as metal but alternately a fuel-compatible plastic, to an end of a plastic fuel rail 14. Fuel rail 14 comprises a number of fuel injectors 15 at various locations along its length so that when assembled to an internal combustion engine, fuel is injected into the combustion chambers for entrainment with air and ensuing ignition. Tube 12 may be a supply tube, a return tube, or a crossover tube depending upon application.
The end of tube 12 shown in FIG. 1 is inserted into the hole in the confronting enlarged end of fuel rail 14 and retained therein by an attaching clip 16. A tubular adapter plug 18 adapts the fit of the inserted end of tube 12 to the enlarged receiving end of fuel rail 14. O-ring seals 20 and 22 are also used. The inserted end of tube 12 also comprises a circumferentially extending, radially outwardly directed flange 24 that is spaced somewhat proximally of its distal terminus.
The enlarged receiving end of fuel rail 14 is provided with certain features for acceptance of clip 16, and these features are a slot 26, and two notches 28 and 30. These two notches may also be considered as slots, because like slot 26, they extend radially completely through the tubular wall of the enlarged receiving end of fuel rail 14, although they are noticeably smaller than slot 26.
As can perhaps be best seen in FIG. 4, slot 26 has a significant circumferential extent about the joint's co-axis 32 shared by the inserted and receiving ends of parts 12 and 14, but nonetheless the slot's circumferential extent is less than one-half of the circumference of the receiving end of fuel rail 14. The slot's two axially extending sides 34 and 36 are parallel, and as viewed in FIG. 4, they extend from the outside of the tubular wall to notches 28 and 30 respectively, where they adjoin respective sides 38 and 40 of the notches at right angles. These sides 38 and 40 in turn extend back to the outside of the tubular wall. Each notch has an opposite side 42 and 44 parallel to the corresponding side 38 and 40. Slot 26 also has two circumferentially extending, parallel sides 46 and 48.
The enlarged receiving end of the fuel rail has several shoulders shaped to receive adapter plug 18, as perhaps best seen in FIG. 5. O-rings seals 20 and 22 are located as shown, with the latter sealing tube 12 to the I.D. of the adapter plug and the former sealing the O.D. of the adapter plug to the I.D. of the fuel rail hole.
Attention is now directed to details of clip 16. The clip has a body comprising a base 50 that is shaped to fit conformedly to slot 26. A fork 52 for fitting over tube 12 projects away from base 50, and a pair of catches 54 and 56 are cantilever-mounted on base 50 on each side of fork 52. These sides, or prongs, radially outwardly of fork 52 comprise open thru-walled channels 58 and 60 that extend lengthwise from base 50 beyond the respective catches. Base 50 and fork 52 cooperatively form axial ends 62 and 64 of the clip that are flat and parallel. As viewed axially the radially outside surface of a respective prong is straight immediately proximal base 50 and beyond that it curves convexly substantially about axis 32.
The joint is made by inserting the end of tube 12, along with the parts 20, 18, and 22, into the hole in the enlarged receiving end of fuel rail 14 so that the flow path through the two parts 12 and 14 is sealed. Such a condition is represented by FIG. 5 although it is to be appreciated that that FIG. 5 shows clip 16 installed. Assembly of clip 16 is performed by inserting it into slot 26 from the position represented by FIG. 1 showing the clip aligned with the slot. Note that the clip has bilateral symmetry so that either axial end can face in either direction. As the clip is being inserted into the slot, inclinded surfaces 66 and 68 at the free ends of catches 54 and 56 engage the sides of the slot, resulting in camming that causes the catches to be flexed more toward the respective channels 58 and 60. The sides 34,36 of slot 26 guide the continued insertion of the clip, as fork 52 fits over tube 12, coming into an overlapping relationship with flange 24, When the clip has been fully inserted, the hooked ends of the catches clear sides 34,36 of the slot, and the catches relax to lodge their hooked ends into notches 28 and 30. This fully inserted position is depicted by FIGS. 4 and 5, and represents the completed joint. Base 50 comprises a surface 70 that is convexly curved substantially about axis 32 to match the circumferential curvature of the fuel rail in the vicinity of slot 26, and hence a neat finished appearance results.
Should it be necessary to disconnect the joint, the fact that notches 28 and 30 are open to the O.D. of the fuel rail allows tool access for pushing the catches clear of the notches to permit removal of the clip.
Clip 16 can be fabricated by conventional plastic molding techniques from a fuel compatable plastic.
While a presently preferred embodiment of the invention has been illustrated and described, it should be appreciated that principles are applicable to other embodiments that fall within the scope of the following claims.
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A fuel tube is attached to a fuel rail by a novel one-piece plastic clip comprising an integral fork for trapping a flange of the fuel tube against withdrawal from the fuel rail hole in which it is received and also comprising integral catches at the sides for catching on notches in the wall of the fuel tube.
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CROSS REFERENCE
The present application claims the benefit of U.S. Provisional Application Ser. 60/847,181, which was filed on Sep. 26, 2006.
BACKGROUND
The computation of a downlink (DL) beamforming weighting vector is based on channel information in the downlink direction. In a time division duplex (TDD) system, the channel information in the downlink direction becomes available as long as the uplink (UL) channel information is known. This is true due to the reciprocal nature of the DL and UL TDD channels. However, in a frequency division duplex (FDD) system, this kind of reciprocal characteristic does not exist between the DL and UL channels. As a result, the information about the DL channel must be sent back to a base transceiver station (BTS) explicitly by a mobile station (MS).
In orthogonal frequency division multiplexing (OFDM) and orthogonal frequency division multiple-access (OFDMA) systems, the carriers of OFDM symbols may experience different levels of impairment. Whenever there is a significant change in the channel quality of a sub-carrier, the MS must send channel information back to the BTS explicitly.
In a TDD OFDMA system, the frequency separation between the DL and UL channels might vary from a fraction of a MHz to a few MHz. This is due to the fact that the BTS scheduler assigns a sub-carrier (frequency) to the DL and UL channels dynamically.
For example, in the TDD version of IEEE 802.16 d/e (WiMax) standard, the DL and UL channels both operate in one of the following frequency bands, i.e., 2.5 MHz, 5 MHz, 10 MHz and 20 MHz. The DL channel is divided into sub-carries, any number of which could form a sub-channel. A permutation is designed to minimize the probability of reusing the sub-carriers in adjacent cells.
Depending on which permutation is used, the DL and UL channels may have few or no sub-carriers in common. FIG. 1 is a diagram illustrating an arbitrary assignment of sub-carriers in the UL and DL channels in a two-dimension diagram of time and frequency domains.
In FIG. 1 , a radio channel is divided into 24 sub-carriers 110 , each of which is represented by an empty block. Nine of the 24 sub-carriers are assigned to a BTS in a cell for downlink traffic. The nine sub-carries are grouped into six sub-channels 120 , each of which is represented by a block with dots. Six of the 24 sub-carriers are assigned to an MS for uplink traffic. The six sub-carries are grouped into five sub-channels 130 , each of which is represented by a block with horizontal lines. Each of the sub-channels is composed of one or more sub-carriers.
Although the frequency separation between the UL and the DL channels is small, the BTS cannot use UL channel information to estimate the DL channel condition with the traditional methods.
As such, what is desired is a method for computing a DL beamforming weighting vector based on UL channel information in a TDD OFDMA system where there is little or no overlap between the sub-carriers in the UL and the DL channels.
SUMMARY
The subject matter described herein relates to a method for obtaining a downlink beamforming weighting vector in a wireless communications system based on channel information about an uplink channel. The method comprises obtaining the channel information about the uplink channel by a means selected from the group comprising training signals, pilot signals, and data signals, wherein the uplink channel comprises a set of uplink sub-channels, calculating a spatial signature of the uplink channel with the channel information, and computing a downlink beamforming weighting vector of a downlink channel with the spatial signature of the uplink channel, wherein the downlink channel comprises a set of downlink sub-channels that share few or no sub-carriers with the set of uplink sub-channels.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a diagram illustrating an arbitrary assignment of sub-carriers in the UL and DL channels.
FIG. 2 is a flow diagram illustrating a method for computing a downlink beamforming weighting vector by using time-domain channel impulse response function.
FIG. 3 illustrates neighborhoods of one or more UL sub-channels.
FIG. 4 is a flow diagram illustrating a method for computing a downlink beamforming weighting vector by selective interpolation or extrapolation.
DESCRIPTION
The following detailed description of the invention refers to the accompanying drawings. The description includes exemplary embodiments, not excluding other embodiments, and changes may be made to the embodiments described without departing from the spirit and scope of the invention. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims.
The subject matter described herein relates to a method for computing a downlink (DL) beamforming weighting vector in a time division duplex (TDD) orthogonal frequency division multiple-access (OFDMA) system without requiring a mobile station (MS) to send DL channel information to a base transceiver station (BTS) explicitly. The DL beamforming weighting vector is computed by using uplink (UL) channel information even when the UL and the DL channels share few or no sub-carriers. It is known to a person with skills in the art that in a situation where some sub-carriers are used for both UL and DL traffic, the complex conjugate of the UL channel coefficient (possibly scaled with a complex number) provides an optimal DL beamforming weighting vector.
In different scenarios, DL beamforming weighting vectors might be computed using a more complex function than the one described above. Regardless of which function is used, the UL channel coefficients play a major role.
Assume that one UL channel is divided into S sub-channels {f 1 f 2 . . . f S }, each of which is composed of a number of sub-carriers. The Partially Used Subchannelization (PUSC) permutation in IEEE 802.16 e/d (WiMax) is one example of a sub-carrier assignment.
A channel impulse response function is defined by the following equation:
h ( t ) = a 1 δ ( t - τ 1 ) + a 2 δ ( t - τ 2 ) + … + a M δ ( t - τ M ) = ∑ i = 1 M a i δ ( t - τ i ) ,
where τ i is the delay time of the i-th multi-path component and a i , a complex number, is the amplitude of the i-th multi-path component. The channel impulse response function h(t) includes all multi-path components with non-zero energy up to the delay time τ M .
For example, a channel might have six multi-path components with the largest delay time equal to 14 times of the sampling rate, i.e., τ M =14. The channel impulse response function h(t) has six terms, each of which corresponds to a multi-path component, and the amplitudes a i of the remaining eight terms are set to zero. The delay time of a multi-path component is a multiple of the sampling interval. If the delay time is not an integer, it is mapped to the next integer that is a multiple of the sampling interval.
FIG. 2 is a flow diagram illustrating a method for computing a DL beamforming weighting vector in accordance with one embodiment. This method is used to calculate a DL beamforming weighting vector when the S sub-channels {f 1 f 2 . . . f S } in the UL channel are spread over the entire frequency band of a radio channel, and the S is large enough, compared with the number of the multi-path components.
In step 210 , the UL channel coefficients are obtained from a covariance method or other conventional approaches, using training signals, pilot signals, or data signals.
In step 220 , by using the UL sub-carrier channel coefficients, the coefficients of the time-domain channel impulse response function h(t) are calculated based on a relationship between the frequency-domain channel coefficients and the time-domain channel impulse response function h(t). This relationship is represented by the following matrix equation:
( r g 1 r g 2 ⋮ r g W ) = ( 1 exp ( - j2π g 1 F ) exp ( - j2π 2 g 1 F ) ⋯ exp ( - j2π ( M - 1 ) g 1 F ) 1 exp ( - j2π g 2 F ) exp ( - j2π 2 g 2 F ) ⋯ exp ( - j2π ( M - 1 ) g 2 F ) ⋮ ⋮ ⋮ ⋮ 1 exp ( - j2π g W F ) exp ( - j2π g W F ) ⋯ exp ( - j2π ( M - 1 ) g W F ) ) ( a 1 a 2 ⋮ ⋮ a M ) ,
where r g i is the receiving signal on frequency g i , of a sub-carrier and F is the size of the Fast Fourier Transform (FFT) of an OFDMA system.
Depending on the structure and distribution of S disjoint sub-channels {f 1 f 2 . . . f S }, it is advantageous to combine predetermined neighboring sub-carriers to form a more reliable set of W disjoint sub-channels {g 1 g 2 . . . g W }.
If the S disjoint sub-channels {f 1 f 2 . . . f S } are well dispersed, then a set of W disjoint sub-channels {g 1 g 2 . . . g W } is the same as a set of {f 1 f 2 . . . f S }. In other words, S equals W.
However, if two or more sub-channels f i {f 1 f 2 . . . f S } are comprised of a set of adjacent sub-carriers, it might be beneficial to compute the average of the receiving signals of the set of adjacent sub-carriers and assign the average signal to one sub-channel denoted by g i . By doing so, the number of sub-channels is reduced and W<=S.
The equation described above represents Fast Fourier Transform (FFT) operation on the channel impulse response function h(t) of the W disjoint sub-channels {g 1 g 2 . . . g W } in the UL channel. The equation can be solved by using matrix operations such as the inverse or pseudo-inverse of the matrix shown described above in connection with step 220 , or by using estimation techniques such as the maximum likelihood, the minimum mean squares error, or the maximum a posteriori method.
In step 230 , after determining the time-domain channel impulse response function h(t) for each of the antennas in the antenna array based on the above equation, the frequency response of the channel can be obtained by taking the FFT of h(t). Subsequently, the spatial signature of a channel is obtained and a DL beamforming weighting vector is calculated.
Since the BTS has no prior knowledge about the actual maximum multi-path delay, the BTS might assume that the maximum multi-path delay M is equal to W. If the maximum multi-path delay M is larger than W, the time-domain channel impulse response function h(t), obtained based on the above equation, may differ from the actual channel impulse response. The difference between the time-domain channel impulse response function h(t) and the actual channel impulse response depends on the signal strength of the multi-path components with delay time larger than M times the sampling rate. The beamforming weighting vector is computed according to the approximated time-domain channel impulse response function h(t).
FIG. 3 illustrates a neighborhood 340 of a UL channel 330 . For a sub-channel 330 in a set of S disjoint sub-channels {f 1 f 2 . . . f S } in the UL channel, its neighborhood 340 is composed of a predetermined number of sub-carriers f N .
The relationship between the UL sub-channel 330 and the DL sub-channel 320 is illustrated by dashed lines drawn from the UL sub-channel 330 to the DL sub-channel 320 in FIG. 3 .
If the neighborhood of one UL sub-channel 350 overlaps with that of another UL sub-channel 360 , the neighborhood could be redefined as an asymmetric neighborhood but it is still based on the center of the UL sub-channel to resolve ambiguity.
FIG. 4 is a flow diagram illustrating a method for computing a DL beamforming weighting vector by selective interpolation or extrapolation.
In step 410 , a BTS identifies the neighborhood of one UL channel, as illustrated in FIG. 3 .
In step 420 , the DL sub-carriers that fall within any of the neighborhoods of the UL sub-channels are identified. A DL beamforming weighting vector is obtained by using the DL sub-carrier channel information.
In step 430 , the DL sub-carriers that fall outside the neighborhoods of the UL sub-channels are determined. Interpolation or extrapolation techniques (either linear or non-linear, depending on the tradeoff between complexity and performance) are used to calculate a DL beamforming weighting vector based on the channel information, about the immediate neighboring UL sub-channels.
The above description is intended by way of example only.
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Described herein is a method for obtaining a downlink beamforming weighting vector in a wireless communications system based on channel information about an uplink channel. The method comprises obtaining the channel information about the uplink channel by a means selected from the group comprising of training signals, pilot signals, and data signals, wherein the uplink channel comprises a set of uplink sub-channels, calculating a spatial signature of the uplink channel with the channel information, and computing a downlink beamforming weighting vector of a downlink channel with the spatial signature of the uplink channel, wherein the downlink channel comprises a set of downlink sub-channels that share few or no sub-carriers with the set of uplink sub-channels.
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This is a 371 of PCT/US95/10232, filed Aug. 10, 1995 which is a CIP of application Ser. No. 08/417,644, filed Apr. 5, 1995 and a CIP of application Ser. No. 08/399,899, filed Mar. 7, 1995, now abandoned.
FIELD OF INVENTION
The present invention relates to novel hemoglobin-containing compositions stabilized to inhibit aggregate formation therein.
BACKGROUND OF THE INVENTION
The oxygen carrying portion of red blood cells is the protein hemoglobin. Hemoglobin is a tetrameric protein molecule composed of two identical alpha globin subunits (α 1 , α 2 ), two identical beta globin subunits (β 1 , β 2 ) and four heme molecules. A heme molecule is incorporated into each of the alpha and beta globins to give alpha and beta subunits. Heme is a large macrocyclic organic molecule containing an iron atom; each heme can combine reversibly with one ligand molecule such as oxygen. In a hemoglobin tetramer, each alpha subunit is associated with a beta subunit to form two stable alpha/beta dimers, which in turn associate to form the tetramer. The subunits are noncovalently associated through Van der Waals forces, hydrogen bonds and salt bridges.
Hemoglobin in solution can be used, for example, as a blood substitute, as a therapeutic for enhancing hematopoiesis, as a means of delivering oxygen or enhancing oxygen delivery to tissues, for hemoaugmentation, for the binding or delivery of nitric oxide or other non-oxygen ligands, as a drug delivery vehicle, as a cell culture additive, as a reference standard, and as an imaging agent. However, storage of hemoglobin solutions can be problematic. Proteins in solution can form aggregates upon long term storage, changes in temperature during storage, or mechanical agitation (Cleland, et al., Crit. Rev. Ther. Drug Carrier Systems 10: 307-377 (1993). To address these problems, many unique formulations have been developed for the stabilization of different proteins in solution. For example, both naturally derived and recombinantly produced proteins have been formulated in solutions containing disaccharides and amino acids (factor VII or factor IX solutions described in PCT Publication WO 91/10439 to Octapharma), human serum albumin (interleukin-2 solutions described in U.S. Pat. No. 4,645,830 to Yasushi et al.), and glycine, mannitol and non-ionic surfactants (human growth hormone solutions described in U.S. Pat. No. 5,096,885 to Pearlman et al.). Although some general guidance is available for the determination of suitable components for formulations for protein solutions, because of the unique nature of individual proteins, no single formulation is suitable for all different proteins. Indeed, Cleland et al. (1993) state that the creation of a formulation that minimizes protein degradation is difficult because there are many factors that interact to determine protein degradation in a formulation. They go on to state that "protein degradation . . . cannot be predicted a priori and must be determined for each protein".
To extend the storage stability of hemoglobin solutions by limiting autooxidation, hemoglobin has been formulated with reducing agents such as cysteine or dithionite, mannitol, glucose and/or alpha tocopherol (Shorr et al., PCT Publication WO 94/01452), in saline solutions or lactated Ringer's solutions that have been modified by the addition of, for example ascorbate, ATP, glutathione and adenosine (Feola et al., PCT Publication WO 91/09615; Nelson et al, PCT Publication WO 92/03153), under deoxygenated conditions with no exogenous reductants (Kandler and Spicussa, PCT Publication WO 92/02239), or in the presence of reducing enzyme systems (Sehgal et al., U.S. Pat. No. 5,194,590). These hemoglobin formulations have been designed to minimize autooxidation of the protein molecule, but none have been designed that specifically reduce the aggregation of the hemoglobin molecules during storage.
Nonetheless, the aggregation of hemoglobin molecules during storage poses significant problems. Moore et al., Art. Org. 16: 513-518 (1992) caution that hemoglobin should not be stored in the frozen state due to the formation of aggregates or precipitates. Moreover, the formation of aggregates in hemoglobin solutions agitated at room temperature has been observed in numerous formulations (Pristoupil and Marik, Biomat. Art. Cells. Art. Org., 18: 183-188, 1990; Adachi and Asakura, J. Biol. Chem., 256: 1824-1830, 1981; Adachi and Asakura, Biochem. 13: 4976-4982,1974). This aggregation of the hemoglobin protein molecule typically does not occur as a result of autooxidation of the hemoglobin heme iron, but rather by interaction of the hemoglobin molecules (Adachi et al., Fed. Proc. 35: 1392 (1976). Aggregates in hemoglobin solutions can increase immunogenicity, reduce functionality and reduce the activity of the protein solution (Cleland et al., supra; Feola et al., Biomat. Art. Cells Art. Org. 16: 217-226 (1988).
Accordingly, there is a need for hemoglobin compositions stabilized against the formation of aggregates. The present invention satisfies this need and provides related advantages as well.
SUMMARY OF THE INVENTION
The present invention relates to compositions containing hemoglobin wherein the hemoglobin is stabilized with a surfactant to inhibit the formation of aggregates. In one embodiment, compositions of the invention contain about 0.001% to about 90% by weight to volume hemoglobin and 0.01 to 1% (weight to volume) of a surfactant and can also include 0-200 mM of one or more buffers, 0-200 mM of one or more alcohols or polyalcohols, 0-300 mM of one or more salts, 0-100 μM of one or more chelating agents and 0-5 mM of one or more reducing agents. In a further embodiment, the compositions can contain 0.01-50% by weight to volume of hemoglobin, 0-50 mM of one or more buffers, 0-200 mM of one or more salts, 0.02%-0.5% (weight to volume) of one or more surfactants, 0-5 mM of one or more reducing agents, 5-50 μM of one or more chelating agents, and is at a pH of about 6.8 to 7.8. Another aspect of the invention are compositions containing about 1 to about 20% by weight to volume of hemoglobin, 5-15 mM sodium phosphate, 100-185 mM sodium chloride, 0.02%-0.08% (weight to volume) polysorbate 80,1-4 mM of ascorbate, 2-40 μM ethylene diamine tetraacetic acid, and is at pH of about 6.8 to 7.6. A still further embodiment of the present invention is a method for stabilizing compositions containing hemoglobin to inhibit the formation of aggregates comprising adding to the composition a stabilizing amount of a surfactant.
Other features and advantages of the invention will be apparent from the following description of the invention and from the claims.
DESCRIPTION OF THE FIGURES
FIG. 1 shows filter pressure during filtration of hemoglobin formulated in a mannitol/bicarbonate buffer system. Open circles show the filter pressure for the mannitol/bicarbonate formulation that did not contain polysorbate 80. Filled circles show the filter pressure for the mannitol/bicarbonate formulation that contained 0.03% polysorbate 80.
FIG. 2 shows filter pressure during filtration of hemoglobin formulated in a sodium chloride/sodium phosphate buffer system. Open circles show the filter pressure for the sodium chloride/sodium phosphate formulation that did not contain polysorbate 80. Filled circles show the filter pressure for the sodium chloride/sodium phosphate formulation that contained 0.03% polysorbate 80.
DETAILED DESCRIPTION OF THE INVENTION
Hemoglobin is generally a tetramer composed of two alpha globin subunits (α 1 , α 2 ) and two beta globin subunits (β 1 , β 2 ). There is no sequence difference between α 1 and α 2 or between β 1 and β 2 . The subunits are noncovalently associated by Van der Waals forces, hydrogen bonds and salt bridges.
Hemoglobin is readily available from a number of natural and recombinant sources. For example, slaughter houses produce very large quantities of hemoglobin-containing blood. Particular species or breeds of animals which produce a hemoglobin especially suitable for a particular use can be specifically bred in order to supply hemoglobin. Transgenic animals can be produced that can express non-endogenous hemoglobin (Logan, J. S. et al., PCT Application Number PCT/US92/05000). Human hemoglobin can be collected from outdated human blood that must be discarded after a certain expiration date.
In addition to extraction from animal sources, the genes encoding subunits of a desired naturally occurring or mutant hemoglobin can be cloned, placed in a suitable expression vector and inserted into an organism, such as a microorganism, animal or plant, or into cultured animal or plant cells or tissues. These organisms can be produced using standard recombinant DNA techniques and hemoglobin produced by these organisms can then be expressed and collected (as described, for example, in Hoffman, S. J and Nagai, K. in U.S. Pat. No. 5,028,588 and Hoffman, et al., WO 90/13645, both herein incorporated by reference).
Purification of hemoglobin from any source can be accomplished using purification techniques which are known in the art. For example, hemoglobin can be isolated and purified from outdated human red blood cells by hemolysis of erythrocytes followed by chromatography (Bonhard, K., et al., U.S. Pat. No. 4,439,357; Tayot, J. L. et al., EP Publication 0 132 178; Hsia, J. C., EP Patent 0 231 236 B1), filtration (Rabiner, S. F. (1967) et al., J. Exp. Med. 126: 1127-1142; Kothe, N. and Eichentopf, B. U.S. Pat. No. 4,562,715), heating (Estep, T. N., PCT publication PCT/US89/014890, Estep, T. N., U.S. Pat. No. 4,861,867), precipitation (Simmonds, R. S and Owen, W. P., U.S. Pat. No. 4,401,652; Tye, R. W., U.S. Pat. No. 4,473,494) or combinations of these techniques (Rausch, C. W. and Feola, M., EP 0 277 289 B1). Recombinant hemoglobins produced in transgenic animals have been purified by chromatofocusing (Townes, T. M. and McCune, PCT publication PCT/US/09624); those produced in yeast and bacteria have been purified by ion exchange chromatography (Hoffman, S. J and Nagai, K. in U.S. Pat. No. 5,028,588 and Hoffman, et al., WO 90/13645).
As used herein, "hemoglobin" means a hemoglobin molecule comprised of at least two globin subunits or domains (dimeric). Hemoglobin can be free in solution or contained within in a cell, liposome or the like. Any globin subunit, whether of natural or recombinant origin, of any hemoglobin, can be crosslinked or genetically fused to another globin subunit. Such crosslinking or genetic fusion can occur within a single hemoglobin molecule or between two or more hemoglobin molecules. Particularly preferred hemoglobins are tetrameric hemoglobins, whether or not genetically fused or chemically crosslinked, and multiples of tetrameric hemoglobins (e.g. octamers, dodecamers, etc.), however produced. Therefore, the term hemoglobin encompasses any for example, non-crosslinked hemoglobin, chemically crosslinked hemoglobin, or genetically fused hemoglobin. In addition, the hemoglobin can be either liganded with any ligand, such as oxygen, carbon monoxide or nitric oxide, or can be in the unliganded (deoxygenated) state.
"Surfactant" as used herein is intended to encompass any detergent that has a hydrophilic region and a hydrophobic region, and, for the purposes of this invention includes non-ionic, cationic, anionic and zwitterionic detergents. Suitable surfactants include, for example, N-laurylsarcosine, cetylpyridinium bromide, polyoxyethylene sorbitan monolaurate (also known as polysorbate 20 or "TWEEN" 20), polyoxyethylene glycol hexadecyl ether ("BRIJ" 35), or polyoxyethylene sorbitan monooleate (also known as polysorbate 80 or "TWEEN" 80). A non-ionic surfactant is preferable for the formulations described herein. Such non-ionic surfactants can be chosen from block co-polymers such as a polyoxamer or polyoxyethylene sorbitan fatty acid esters, for example, polysorbate 20 or polysorbate 80. Polysorbate 80 is preferred for the compositions of this invention.
A stabilizing amount of surfactant is an amount sufficient to inhibit the formation of aggregates in hemoglobin-containing compositions. Such aggregate formation can occur during, for example, long term storage, freezing and thawing, or mechanical agitation. Inhibition of such aggregate formation occurs when the aggregate formation in a composition containing hemoglobin and a surfactant is significantly inhibited relative to aggregate formation in the same composition containing hemoglobin that does not contain the surfactant. Significant inhibition of aggregation occurs when aggregate formation is at least 10% less in the hemoglobin containing composition with surfactant than in a comparable formulation that does not contain surfactant, preferably at least 50% less, more preferably at least 70% less, and most preferably at least 90% less.
"Aggregates" refers to hemoglobin molecules that can be soluble or insoluble and are detectable by aggregate detection methods such as visual inspection, light scattering methods such as spectrophotometry and dynamic light scattering, particle counting methods, filtration backpressure increases or other suitable methods for the determination of aggregates.
The compositions of the invention can be incorporated in conventional formulations including but not limited to tablets, capsules, caplets, compositions for subcutaneous, intravenous, or intramuscular injection or oral administration, reagent solutions for standardization of clinical instrumentation, large volume parenteral solutions useful as blood substitutes, etc. The compositions can be formulated by any method known in the art, including, for example, simple mixing, sequential addition, emulsification, and the like. The formulations of the invention comprise hemoglobin and surfactants as the active ingredients and can include other active or inert agents. For example, a parenteral therapeutic composition can comprise a sterile isotonic saline solution containing between 0.001% and 90% (w/v) hemoglobin. Suitable compositions can also include 0-200 M of one or more buffers (for example, acetate, phosphate, citrate, bicarbonate, or Good's buffers). Salts such as sodium chloride, potassium chloride, sodium acetate, calcium chloride, magnesium chloride can also be included in the compositions of the invention at concentrations of 0-2 M. In addition, the compositions of the invention can include 0-2 M of one or more carbohydrates (for example, reducing carbohydrates such as glucose, maltose, lactose or non-reducing carbohydrates such as sucrose, trehalose, raffinose, mannitol, isosucrose or stachyose) and 0-2 M of one or more alcohols or poly alcohols (such as polyethylene glycols, propylene glycols, dextrans, or polyols). The compositions of the invention also contain 0.005-1% of one or more surfactants. The compositions of the invention can also be at about pH 6.5-9.5. In another embodiment, the composition contains 0-300 mM of one or more salts, for example chloride salts, 0-100 mM of one or more non-reducing sugars, 0-100 mM of one or more buffers, and 0.01-0.5% of one or more surfactants. In a still further embodiment, the composition contains 0-150 mM NaCl, 0-10 mM sodium phosphate, and 0.01-0.1% surfactant, pH 6.6-7.8. Most preferably, the hemoglobin-containing composition includes 5 mM sodium phosphate, 150 mM NaCl, and 0.025% to 0.08% polysorbate 80, pH 6.8-7.6.
Other components can be added if desired. For example 0-5 mM reducing agents such as dithionite, ferrous salts, sodium borohydride, and ascorbate can be added to the composition, most preferably 0.5-3 mM ascorbate is added to the composition. Additional additives to the formulation can include anti-oxidants (e.g. ascorbate or salts thereof, alpha tocopherol), anti-bacterial agents, chelating agents such as, for example, ethylene diamine tetraacetic acid (EDTA) or ethylene glycol-bis(β-aminoethyl ether)N,N,N',N',-tetraacetic acid (EGTA), oncotic pressure agents (e.g. albumin or polyethylene glycols) and other formulation acceptable salts, sugars and excipients known to those of skill in the art.
Each formulation according to the present invention can additionally comprise inert constituents including carriers, diluents, fillers, salts, and other materials well-known in the art, the selection of which depends upon the particular purpose to be achieved and the properties of such additives which can be readily determined by one skilled in the art.
The formulation of the instant invention can be used to treat anemia, both by providing additional oxygen carrying capacity in a patient that is suffering from anemia, and by stimulating hematopoiesis. In addition, because the distribution of the hemoglobin in the vasculature is not limited by the size of the red blood cells, the hemoglobin of the present invention can be used to deliver oxygen to areas that red blood cells cannot penetrate. These areas can include any tissue areas that are located downstream of obstructions to red blood cell flow, such as areas downstream of thrombi, sickle cell occlusions, arterial occlusions, angioplasty balloons, surgical instrumentation and the like.
The formulated hemoglobin solutions of the instant invention can also be used as replacement for blood that is removed during surgical procedures where the patient's blood is removed and saved for reinfusion at the end of surgery or during recovery (acute normovolemic hemodilution or hemoaugmentation).
Because the purified hemoglobin solutions of the instant invention can bind nitric oxide and other non-oxygen ligands as well as oxygen, the formulations of the instant invention are also useful for the binding or delivery of nitric oxide or non-oxygen ligands. These non-oxygen ligands can be bound or delivered both in vivo or in vitro. For example, the purified hemoglobin solutions of the instant invention may be used to remove excess nitric oxide from a living system. Excess nitric oxide has been implicated in conditions ranging from hypotension to septic shock. Likewise, nitric oxide or other non-oxygen ligands may be delivered to a system to alleviate a disease condition. For example, nitric oxide could be delivered to the vasculature to treat hypertension. Other therapeutic uses of the instant invention can include drug delivery and in vivo imaging.
The hemoglobin formulations of the present invention can also be used for a number of in vitro applications. For example, the delivery of oxygen by the purified hemoglobin solutions of the instant invention can be used for the enhancement of cell growth in cell culture by maintaining oxygen levels in vitro. Moreover, the purified hemoglobin solutions of the instant invention can be used to remove oxygen from solutions requiring the removal of oxygen, and as reference standards for analytical assays and instrumentation.
EXAMPLES
The following examples are provided by way of describing specific embodiments of the present invention without intending to limit the scope of the invention in any way.
EXAMPLE 1
Measurements of Aggregate Formation
Measurement of particles≧2 μm--Light obscuration functions by measuring the decrease in signal strength caused by a particle passing through a laser. By comparing the decrease in signal strength to that of a series of latex spheres of known size, the sizes of the particles in the sample were determined. Particles≧2 μm were measured by light obscuration with a HIAC/Royco (Silver Springs, Md.) particle counter model 8000A equipped with a model 3000 sampler. Measurements were made following dilution of the sample (0.5-1 ml aliquots) to 10 ml in 150 mM NaCl, 5 mM sodium phosphate buffer, pH 7.4. Numbers represent the cumulative particle counts≧2 μm.
Filter pressure assay--As a solution is passed through a filter, the filter is slowly blocked and the filter pressure increases as a function of aggregate accumulation on the filter. This method provides an indirect measurement of aggregation≧0.2 μm which is not detectable by the light obscuration described above. The ability of a hemoglobin-containing sample to block a 0.2 μm filter was determined using an "IVAC" infusion pump (San Diego, Calif.). Briefly, following shaking or freeze/thawing each sample was transferred to a 500 ml polyvinyl chloride bag and pumped at 500 ml/hr through a 0.2 μm "PALL" in-line filter (East Hills, N.Y.). The back pressure on the filter was monitored directly from the "IVAC" pump.
EXAMPLE 2
Determination of Concentration of Polysorbate 80 required to inhibit formation of aggregates≧2 μm during freeze/thaw
Hemoglobin was expressed, prepared and purified as described in co-owned PCT publication number, WO 95/13034, filed Nov. 14,1994, entitled "Purification of Hemoglobin". Suitable concentrations of polysorbate 80 for reduction of aggregation were determined by subjecting hemoglobin formulated with increasing concentrations of polysorbate 80 to repeated freeze/thaw cycles. Aliquots (1.5 ml) of 50 mg/ml hemoglobin in 150 mM NaCl, 5 mM phosphate, pH 7.4, were formulated with and without polysorbate 80 and sealed in 3.5 ml glass vials. The samples were frozen at either -80° C. or -20° C. for 24 hour periods. On selected days two vials were removed from each freezer, slowly thawed in water at 25° C. and the number of aggregates determined using the HIAC/Royco Particle Counter. The remaining samples were thawed at room temperature then refrozen at either -80° C. or -20° C.
In the absence of polysorbate 80 the number of aggregates≧2 μm increased by approximately 3-fold at -20° C. (Table 1) and approximately 5-fold at -80° C. (Table 2) after five freeze/thaw cycles. The presence of 0.005-0.01% polysorbate 80 could not prevent the increase at either temperature and at -20° C. appeared to exacerbate the increase in aggregation seen in the absence of polysorbate. In contrast, 0.025-0.1% polysorbate 80 inhibited the formation of aggregates after the freeze/thaw cycles relative to the formation of aggregates in compositions that did not contain polysorbate by between approximately 28-46%. During the course of the freeze/thaws the number of aggregates in the samples containing 0.025% polysorbate 80 varied from 1-1.6-fold at -20° C. and from 1.2-1.9-fold at -80° C. Furthermore, the final degree of aggregation in formulations containing 0.05 to 0.1% polysorbate 80 was significantly less (˜45-70%) than the aggregation observed in compositions that did not contain surfactant. The samples containing 0.025% polysorbate 80 or greater demonstrated a decreased tendency to aggregate compared to the samples containing 0.01% or less (inhibition of aggregate formation in the presence of 0.025% polysorbate was at least 25% relative to formulations that did not contain surfactant).
TABLE 1______________________________________Effect of Polysorbate 80 on particle aggregation: Freeze/Thaw -20°C.% (w/v) Number Freeze/Thaw CyclesPolysorbate 80 0 2 5______________________________________0.0% 1500 3300 42000.005% 3800 5100 72000.01% 3000 4200 75000.025% 2000 3200 30000.05% 1400 1900 23000.1% 970 1800 2200______________________________________
TABLE 2______________________________________Effect of Polysorbate 80 on particle aggregation: Freeze/Thaw -80°C.% (w/v) Number Freeze/Thaw CyclesPolysorbate 80 0 2 5______________________________________0.0% 1500 3300 78000.005% 3800 5500 90000.01% 3000 4300 56000.025% 1955 3100 36000.05% 1400 2700 23000.1% 1000 2000 2400______________________________________
EXAMPLE 3
Determination of Concentration of Polysorbate 80 required to inhibit formation of aggregates≧2 μm during mechanical agitation
Hemoglobin was prepared as described in Example 2. Suitable concentrations of polysorbate 80 for reduction of aggregation were determined by subjecting hemoglobin formulated with increasing concentrations of polysorbate 80 to mechanical agitation. Aliquots (1.5 ml) of 50 mg/ml hemoglobin in 150 mM NaCl, 5 mM phosphate, pH 7.4, were formulated with and without polysorbate 80 and were sealed in 3.5 ml glass vials. The samples were then placed on their sides on an orbital shaker and shaken for 1 hour at 4° C. at 90, 120, 180 and 240 rpm. A 1 ml aliquot was removed and aggregates≧2 μm were counted using a HIAC/Royco Particle counter as described in Example 1. Because no aggregate formation occurred during the course of the experiment at 90 or 120 rpm, only the control data (no mechanical agitation, listed as 0 rpm in Table 3) and the data for 180 and 240 rpm are reported below (Table 3). Addition of the surfactant at a concentration of 0.025% or greater inhibited the formation of aggregates while addition of 0.01% of the surfactant did not demonstrate any significant protection against aggregation. At 240 rpm the sample containing 0.025% polysorbate 80 showed an increase in the number of aggregates compared to the 0.05% polysorbate 80 sample. In other experiments no increase in aggregation was observed by decreasing the polysorbate concentration from 0.05% to 0.025%.
TABLE 3______________________________________Effect of Polysorbate 80 on particle aggregation: Mechanical Agitation% (w/v)Polysorbate 80 0 rpm 180 rpm 240 rpm______________________________________0.0% 2200 140,000 570,0000.0125% 1800 110,000 710,0000.025% 2100 3700 18,0000.05% 1400 1100 5500______________________________________
EXAMPLE 4
Determination of concentration of polysorbate 80 required to inhibit increases in filtration backpressure: mechanical agitation
Hemoglobin was prepared as described in Example 2 and formulated in either 150 mM NaCl, 5 mM sodium phosphate, pH 7.4 (NaCl/sodium phosphate formulation) or 100 mM NaCl, 50 mM mannitol, 3 mM KCl, 2 mM CaCl 2 , 1M MgCl 2 and 10 mM NaHCO 3 , pH 7.6 (mannitol/bicarbonate formulation). Controls did not have polysorbate 80 added to the formulations while the test solutions of both the NaCl/sodium phosphate formulation and the mannitol/bicarbonate formulation contained 0.03% polysorbate 80. Aliquots (500 ml) of control and test hemoglobin solutions were placed in 1 L polycarbonate bottles and were agitated for 1 hour at 4° C. on an orbital shaker at 180 rpm. Following shaking, an aliquot (1 ml) of each sample was removed for particle content determination using the Hiac/Royco instrumentation as described above. The remaining volume of each sample was then transferred into a polyvinyl chloride bag and pumped through a 0.2 μm PALL in-line filter at 500 ml/hour using an IVAC infusion pump. The filter pressure was monitored directly from the IVAC pump.
The hemoglobin formulated without polysorbate 80 blocked the filter within 3 minutes irrespective of the other components of the solution (i.e. salts, etc.). In contrast, in the presence of polysorbate 80, ˜500 ml of material formulated in either formulation did not cause overpressuring of the filter (backpressure greater than 500 mm Hg) during the course of the filtration. Filter blockage in the formulations that did not contain surfactant was most probably due to the approximately 300-400 fold increase in aggregates≧2 μm that resulted from mechanical agitation. After one hour of shaking, the mannitol/bicarbonate/no surfactant formulation contained>700,000 counts per ml, while the NaCl/sodium phosphate/no surfactant formulation contained>600,000 counts per ml. Counts per ml were determined using the Hiac/Royco Particle Counter described in Example 1.
EXAMPLE 5
Determination of concentration of polysorbate 80 required to inhibit increases in filtration backpressure: freeze/thaw
Hemoglobin was prepared as described in Example 2 and formulated in either 150 mM NaCl, 5 mM sodium phosphate, pH 7.4 (NaCl/sodium phosphate formulation) or 100 mM NaCl, 50 mM mannitol, 3 mM KCl, 2 mM CaCl 2 , 1 mM MgCl 2 and 10 mM NaHCO 3 , pH 7.6 (mannitol/bicarbonate formulation). Controls did not have polysorbate 80 added to the formulations while the test solutions of both the NaCl/sodium phosphate formulation and the mannitol/bicarbonate formulation contained 0.03% polysorbate 80. Aliquots (500 ml) of control and test hemoglobin solutions were placed in 1 L polycarbonate bottles and frozen at -20° C. for 24 hours, then thawed in a 25° C. water bath. The freezing and thawing cycles were repeated three times. After the freeing and thawing, each sample was transferred into a polyvinyl chloride bag and pumped through a 0.2 μm PALL inline filter at 500 ml/hour using an IVAC infusion pump. The filter pressure was monitored directly from the IVAC pump.
Filtration of the material containing polysorbate 80 demonstrated no increase in filter pressure for both formulations (FIGS. 1 and 2). In contrast, the sample in the mannitol/bicarbonate formulation that did not contain polysorbate 80 achieved maximum filter pressure within 35 minutes. After replacement of the filter, backpressure again began to rise following another 12 minutes of filtration (FIG. 1). The NaCl/sodium phosphate/no polysorbate formulation exhibited behavior similar to the mannitol/bicarbonate formulation that did not contain surfactant. Filtration of the NaCl/sodium phosphate/no polysorbate formulation resulted in increasing filtration backpressure during the 50 minutes of filtration (FIG. 2).
EXAMPLE 6
Determination of Concentration of Polysorbate 80 required to inhibit formation of aggregates≧2 μm during mechanical agitation in the presence of EDTA
Hemoglobin was prepared as described in Example 2. Suitable concentrations of polysorbate 80 for reduction of aggregation were determined by subjecting hemoglobin formulated with increasing concentrations of polysorbate 80 to mechanical agitation. Aliquots (1.5 ml) of 83 mg/ml hemoglobin in 150 mM NaCl, 5 mM phosphate, 25 μM EDTA, pH 7.4, were formulated with and without polysorbate 80 and were sealed in 3.5 ml glass vials. These samples were then shaken for 1.5 hours at 25° C. and 150 rpm on a rotary shaker. A 1 ml aliquot was removed and aggregates≧2 μm were counted using a HIAC/Royco Particle counter as described in Example 1. As in the case with no EDTA, addition of the surfactant at a concentration of ˜0.03% or greater inhibited the formation of aggregates.
TABLE 4______________________________________Effect of Polysorbate 80 on particle aggregation in thepresence of EDTA: Mechanical Agitation Time on% (w/v) shakerPolysorbate 80 (hours) Counts ≧2 μm______________________________________0.0% 0 43000.0% 1.5 107,0000.03% 1.5 64000.045% 1.5 40000.06% 1.5 3800______________________________________
The foregoing description of the invention is exemplary for purposes of illustration and explanation. It will be apparent to those skilled in the art that changes and modifications will be possible without departing from the spirit and the scope of the invention. It is intended that the following claims be interpreted to embrace all such changes and modifications.
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The present invention relates to hemoglobin compositions stabilized against the formation of aggregates. Such compositions contain at least a surfactant, said surfactant not being an adduct of a polymer and an anionic ligand. The present invention further relates to methods of making such hemoglobin compositions.
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FIELD OF THE INVENTION
[0001] The present invention relates to an image sensing apparatus, and more particularly, to a signal readout structure for an image sensing apparatus.
BACKGROUND OF THE INVENTION
[0002] Recent technical advances in digital still cameras, digital video cameras and other such image input devices have tended to provide sensors with more and more picture elements (hereinafter pixels) in order to further improve the quality of the images formed, with the result that higher readout speeds are required as well. In order to meet such a need, a readout method has been developed by which the pixel signals have been divided into a plurality of readout channels. A description of this conventional method is now given with reference to FIGS. 11 and 12.
[0003] [0003]FIG. 11 is a diagram of the structure of a conventional image sensing apparatus. FIG. 12 is a timing chart showing the drive timing and output signals of a conventional image sensing apparatus.
[0004] The image sensing apparatus shown in FIG. 11 has a plurality of pixels 3101 arranged in two dimensions and consisting of optical black pixels arranged and shielded by a light-blocking film and effective pixels with no light-blocking film; readout channels 3071 and 3072 for reading out image signals from each of the plurality of pixels selected according to a control signal from a vertical scan circuit 3102 ; and an output terminal 3120 for outputting signals after increasing either the waveform or the drive force of the signals after the timing with which the signals are read out by the readout channels 3071 , 3072 has been adjusted and the signals have been passed through a buffer circuit 3119 . Note that only 5×4 pixels are shown in FIG. 11 for simple explanation.
[0005] In addition, the readout channels 3071 , 3072 have readout circuits 3106 , 3111 , which in turn have line memories 3104 , 3109 for storing pixel signals read from each of the plurality of pixels 3101 and horizontal scan circuits 3105 , 3110 for forwarding the stored pixel signals in response to horizontal shift pulses input from input terminals 3122 , 3123 . In addition, the readout channels 3071 , 3072 also have amplifiers 3107 , 3112 for amplifying the signals that are read out and clamps 3124 , 3125 for clamping the amplified signals at a particular electric potential.
[0006] A description is now given of the operation of the conventional fixed image sensing apparatus having the structure described above, with reference to FIG. 11 .
[0007] First, when light strikes each of the plurality of pixels 3101 , the pixels 3101 generate pixel signals of a level determined by the amount of incoming light. Next, pixel signals read out from odd-numbered columns in a row of pixels 3101 selected by the vertical scan circuit 102 are stored in the line memory circuit 3104 , and at the same time pixel signals read from even-numbered columns in the same row are stored in the line memory circuit 3109 .
[0008] Next, the horizontal scan circuit 3105 inputs a horizontal shift pulse from either outside or inside the chip from the input terminal 3122 . Based on the input horizontal shift pulse, the pixel signals read out to the line memory circuit 3104 are then sequentially selected and output to the amplifier 3107 . At the amplifier 3107 , the input pixel signals are amplified and output to a processing circuit (not shown in the diagram) from an output terminal 3108 .
[0009] Similarly, the horizontal scan circuit 3110 , based on a horizontal shift pulse input from the input terminal 3123 , sequentially selects pixel signals read out to the line memory circuit 3109 and outputs them to the amplifier 3112 . At the amplifier 3112 , the input pixel signals are amplified and output to a processing circuit (not shown in the diagram) from the output terminal 3113 .
[0010] In addition, the dark level signals output from the optical black pixels within the plurality of pixels 3101 are then clamped at a desired electric potential using clamps 3124 , 3125 . Further, at each of output terminals 3108 and 3113 , switches 3116 and 3117 connected in parallel are switched ON/OFF in alternating sequence so as to output pixel signals from the odd-numbered columns of pixels and the even-numbered columns of pixels from the output terminal 3120 via the output buffer circuit 3119 .
[0011] [0011]FIG. 12 shows horizontal shift pulses 1 and 2 input at input terminals 3122 , 3123 of FIG. 11, a dark level signal and a pixel signal output from output terminals 3108 and 3113 , a clamp pulse clamping, the ON/OFF action of the switches 3116 and 3117 , and a dark level signal and a pixel signal output from output terminal 3120 . FIG. 12 shows a state in which a pulse wave is input to input terminals 3122 , 3123 in, for example, 6 clock parts each.
[0012] In FIG. 12, of the signals output from output terminal 3120 , the pixel signals and dark level signals read out from pixels of a given row of columns 1 - 12 are assigned reference numerals ( 1 )-( 12 ), respectively. Also, pixel signals of output terminals 3108 and 3113 are given reference numerals corresponding to those of the signals at output terminal 3120 . Reference numerals ( 1 )-( 6 ) correspond to dark level signals obtained from the optical black pixels and reference numerals ( 7 )-( 12 ) correspond to the pixel signals from the effective pixels.
[0013] According to FIG. 12, the dark level signals ( 1 ), ( 3 ) and ( 5 ) and the pixel signals ( 7 ), ( 9 ) and ( 11 ), synchronized to horizontal shift pulse 1 , are sequentially output at the output terminal 3108 . Similarly, dark level signals ( 2 ), ( 4 ) and ( 6 ) and pixel signals ( 8 ), ( 10 ) and ( 12 ), synchronized to horizontal shift pulse 2 , are sequentially output at the output terminal 3113 . By activating the clamps 3124 , 3125 at the point at which the dark level signals ( 1 ) and ( 2 ) are output from the output terminals 3108 , 3113 , the dark level signals are clamped at a desired electric potential.
[0014] Next, by switching switches 3116 and 3117 ON/OFF in alternate succession, the dark level signals ( 1 )-( 6 ) and the pixel signals ( 7 )-( 12 ) are output at the output terminal 3120 . By so doing, although the output terminals 3108 and 3113 operate at half-cycle with respect to the clock rate at output terminal 3120 , the readout speed can be increased relatively easy.
[0015] Moreover, when reading out signals using multiple channels as described above, a structure that always reads out signals of the same color from the channels is disclosed in Japanese Patent Application Laid-Open No. 9-46480, and a method for correcting offset error at each channel is disclosed in Japanese Patent Application Laid-Open No. 2001-245221.
[0016] Moreover, Patent Application Japanese Laid-Open No. 5-328224 discloses a structure using multiple channels to read a plurality of pixels in the horizontal direction and using a switch to perform time division multiplexing on the signals read by the multiple channels. According to such a structure, even if the readout speed at each of the channels is slow, the charge readout can be read at high speed and the number of terminals can be reduced by time division multiplexing of the read-out electric charge signals.
[0017] However, Japanese Laid-Open Patent Application No. 9-46480 and 2001-245221 have a disadvantage in that they increase the number of output pins because four or five output pins are required for each output terminal. In addition, Japanese Laid-Open Patent Application No. 5-328224 has the following problem, described with reference to FIG. 13.
[0018] [0018]FIG. 13 is a diagram of the structure of another conventional image sensing apparatus, illustrating the adaptation of the structure disclosed in Japanese Laid-Open Patent Application No. 5-328224 to a color readout. For the sake of simplicity, two horizontal scan circuits are used to read out a charge from two pixels at a time. In FIG. 13, a plurality of pixels 1 are covered by a Bayer arrangement filter, with the G-B pixel columns being read by the first horizontal scan circuit 3 and the R-G pixel columns being read by the second horizontal scan circuit 4 .
[0019] In a case in which, as depicted here, an Nth line is selected and read out by the vertical scan circuit 2 , a G signal of every other pixel is continuously output from a first differential amplifier 5 and an R signal of every other pixel is continuously read out from a second differential amplifier 6 . When time division multiplexed by a multiplexer 7 , these G and R signals are output in alternating sequence from an output terminal (OUT).
[0020] However, by outputting signals of different colors from a single output terminal using such multiplexing as described above, there is a risk that the two colors will mix, and in any case such an arrangement complicates downstream signal processing circuit structures for operations such as signal separation outside semiconductor image sensing apparatuses.
[0021] The reason is as follows: Parasitic resistance R and parasitic capacitance C occurs in the wires inside the image sensing apparatus, and a change in electric potential in such wiring can be explained as a transient phenomenon. That is, the electric potential change in wiring with such parasitic elements is determined by the parasitic resistance R and the parasitic capacitance C, and with a time constant CR, a V(t) can be expressed by equation (1):
V ( t )= V o ε −(1 /RC ) t (1)
[0022] where V o is the electric potential in a steady state of the wiring and ε is a natural constant.
[0023] As can be understood from equation (1), V(t) changes exponentially with time and approaches V o .
[0024] Thus, the waveform output from the output terminal 3120 of FIG. 11 (output terminal 3120 of FIG. 12) has a different output level at ( 7 ) and ( 8 ), so it takes time for the electric potential to fall from ( 7 ) to ( 8 ), as is the case with the output level in the transition from ( 6 ) to ( 7 ). One of the reasons for the large differences in the continuous output level at the output terminal 3120 is that the outputs from terminals 3113 and 3108 are outputs from pixels of color filters of different transmissivity.
SUMMARY OF THE INVENTION
[0025] Accordingly, the present invention has been made in consideration of the above-described situation, and has as its object to output signals of all colors at high speed from a color image sensing apparatus as well as form an image of superior picture quality which avoids color mixing even when multiplexing signals from multiple output systems at high speed with a comparatively simple structure, while holding the number of output pins to a minimum.
[0026] According to the present invention, the foregoing objects are attained by providing an image sensing apparatus comprising: a photoelectric converter having a plurality of pixels covered by color filters composed of a plurality of colors; a plurality of common readout units adapted to sequentially output signals from the plurality of pixels, a time division multiplex (TDM) unit adapted to perform time division multiplexing on signals from the plurality of common readout units so as to output time division multiplexed signals; and a read-out control unit adapted to read out the signals from the plurality of pixels to the common readout units so that signals from pixels covered with color filters of the same color are multiplexed continuously.
[0027] Other objects, features, effects and advantages of the present invention will be apparent from the following description, taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention, in which:
[0029] [0029]FIG. 1 is a diagram of the structure of an image sensing apparatus according to a first embodiment of the present invention;
[0030] [0030]FIG. 2 is a timing chart showing the drive timing and output signals of the image sensing apparatus of FIG. 1;
[0031] [0031]FIG. 3 is a diagram of the structure of an image sensing apparatus according to a second embodiment of the present invention;
[0032] [0032]FIG. 4 is a timing chart showing the drive timing and output signals of the image sensing apparatus of FIG. 3;
[0033] [0033]FIG. 5 is a schematic diagram of the structure of an image sensing apparatus according to a third embodiment of the present invention;
[0034] [0034]FIG. 6 is a diagram of the structure of an image sensing apparatus according to a first variation of the present invention;
[0035] [0035]FIG. 7 is a diagram of the structure of an image sensing apparatus according to a second variation of the present invention;
[0036] [0036]FIG. 8 is a diagram of the structure of an image sensing apparatus according to a third variation of the present invention;
[0037] [0037]FIG. 9 is a diagram of the structure of an image sensing apparatus according to a fourth variation of the present invention;
[0038] [0038]FIG. 10 is a block diagram showing the structure of an image-forming system according to a fourth embodiment of the present invention;
[0039] [0039]FIG. 11 is a diagram of the structure of a conventional image sensing apparatus;
[0040] [0040]FIG. 12 is a timing chart showing the drive timing and output signals of a conventional image sensing apparatus; and
[0041] [0041]FIG. 13 is a diagram of the structure of another conventional image sensing apparatus.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0042] Preferred embodiments of the present invention will be described in detail in accordance with the accompanying drawings.
[0043] (First Embodiment)
[0044] A description is now given of the first embodiment of the present invention, with reference to FIGS. 1 and 2.
[0045] [0045]FIG. 1 is a diagram of the structure of an image sensing apparatus according to a first embodiment of the present invention. FIG. 2 is a timing chart showing the drive timing and output signals of the image sensing apparatus of FIG. 1.
[0046] In FIG. 1, reference numeral 1 denotes a pixel having a Bayer arrangement color filter. The numbers inside the parentheses next to the color designations R (red), G (green) and B (blue), are the pixel coordinates. It should be noted that, for simplicity of description, the present example uses a 6×6 arrangement of pixels, but in fact an extremely large number of pixels are arrayed in an actual arrangement.
[0047] The pixels 1 are each connected to line selection lines L 1 -L 6 at each line, with the line selection lines L 1 -L 6 being turned HIGH (hereinafter H) in sequence by line selection signals supplied from the vertical scan circuit 2 and a line for reading the charge is selected. In the example shown in FIG. 2, a line selection signal ΦL 1 supplied to the line selection line L 1 is H, selecting the first line (at a time t 1 ). At substantially the same time at which the readout line is selected and prior to the readout of the charge, signals ΦPTN 1 and ΦPTN 2 are turned H and MOS 21 , 22 are turned ON, reading the noise component of the selected line out to a capacitor CTN. Next, at a time t 2 , signals ΦPTS 1 and ΦPTS 2 are turned H and MOS 23 , 24 are turned ON, so that the photoelectric charge accumulated in the pixels 1 of the selected line (which is a photoelectric charge overlaid with a noise component) is read out to the capacitor CTS. By so doing, the noise component and the image signal component overlaid by the noise component of the pixels 1 are each handled by the capacitors CTN and CTS, respectively.
[0048] Next, the charges held in capacitors CTN, CTS are sent to differential amplifiers 15 - 18 by column selection signals supplied from first through fourth horizontal scan circuits 11 - 14 comprised of shift resistors. The differential amplifiers 15 - 18 subtract the noise components from the image signal components overlaid by the noise components and output image signals from which the noise components are deleted.
[0049] At a time t 3 , the first and second horizontal scan circuits 11 , 12 turn ΦH 1 and ΦH 2 to H and the corresponding MOS 25 - 28 ON, so that the charges read from G ( 1 , 1 ) and R ( 1 , 2 ) to the capacitors CTN, CTS are each sent to the differential amplifiers 15 and 16 via signal lines 101 , 102 . Differential amplifier 15 deletes the noise component from the photoelectric charge overlaid with the noise component and outputs (OUT 1 ) an image signal (denoted by the same reference numeral as the pixels, in this case G ( 1 , 1 )). Similarly, differential amplifier 16 outputs image signal R ( 1 , 2 ) (OUT 2 ). Multiplexers 19 and 20 each select differential amplifiers 15 and 16 and output image signals G( 1 , 1 ) and R( 1 , 2 ), respectively.
[0050] Then, at a time t 4 , the third and fourth horizontal scan circuits 13 and 14 turn ΦH 3 as well as ΦH 4 to H, sending the charges read to the capacitors CTN and CTS from G( 1 , 3 ) and R( 1 , 4 ) to the respective differential amplifiers 17 and 18 via the signal lines 103 , 104 .
[0051] Then, the differential amplifier 17 removes the noise component from the photoelectric charge overlaid with the noise component, outputting image signal G( 1 , 3 ) (OUT 3 ). Similarly, the differential amplifier 18 outputs image signal R ( 1 , 4 ) (OUT 4 ). The multiplexers 19 and 20 then output image signals G( 1 , 3 ) and R( 1 , 4 ), respectively, by selecting the differential amplifiers 17 , 18 .
[0052] By repeating the above-described process for each horizontal line, G signals G( 1 , 1 ), G( 1 , 3 ), G( 1 , 5 ) of every other pixel are output from output terminal OUT A of multiplexer 19 and R signals R( 1 , 2 ), ( 1 , 4 ), ( 1 , 6 ) of every other pixel are output from output terminal OUT B of multiplexer 20 .
[0053] Similarly, selecting a second line by having the vertical scan circuit 2 turn ΦL 2 to H and repeating the above-described operation for one line causes B signals B( 2 , 1 ), B( 2 , 3 ), B( 2 , 5 ) of every other pixel to be output from output terminal OUT A of multiplexer 19 , and G signals G( 2 , 2 ), G( 2 , 4 ) and G( 2 , 6 ) of every other pixel to be output from output terminal B of multiplexer 20 .
[0054] As described above, according to the first embodiment of the present invention, by reading out and multiplexing signals output via multiple readout signal lines, the speed of readout can be improved and at the same time the number of output pins can be reduced compared to a case in which signals are output directly from the readout signal lines. Also, because the present invention multiplexes signals of the same color, the signal level of the outputs from OUT A and B can be kept virtually steady, thus avoiding color mixing and making it possible to output color signals from a color fixed image sensing apparatus at high speeds. Also, by allotting the color output system among multiple readout means as shown in FIG. 1 like the first embodiment, it becomes possible to multiplex the top two system readout means as well as the bottom two system readout means. Moreover, since the top OUT 1 and OUT 3 are adjacent to each other, and since the bottom OUT 2 and OUT 4 are also adjacent to each other, the problem of delay and the drive force can be ignored so that the timing of the multiplexing can be adjusted easily.
[0055] Moreover, since signals of the same color are output from the output pins, there is no need to perform color separation at a downstream signal processing circuit, thus making it possible to simplify the structure and the processes of such signal processing circuit.
[0056] (Second Embodiment)
[0057] A description will now be given of the second embodiment of the present invention, with reference to the accompanying drawings.
[0058] It should be noted that, in order to simplify the explanation, a description of the drive method and noise deletion method is omitted for the second and all subsequent embodiments of the present invention described herein below.
[0059] [0059]FIG. 3 is a diagram of the structure of an image sensing apparatus according to a second embodiment of the present invention. FIG. 4 is a timing chart showing the drive timing and output signals of the image sensing apparatus of FIG. 3. As can be seen in FIG. 3, in the second embodiment, the first and third horizontal scan circuits 11 and 13 of the first embodiment shown in FIG. 1, as well as the second and fourth horizontal scan circuits 12 and 14 also shown in FIG. 1, have each been replaced with a single horizontal scan circuit. It should be noted that, in FIG. 3, structures that are the same as those shown in FIG. 1 are given identical reference numerals.
[0060] In FIG. 3, reference numeral 31 denotes a first horizontal scan circuit and reference numeral 32 denotes a second horizontal scan circuit. As shown in FIG. 4, the cycle of the clock signal supplied to the first and second horizontal scan circuits 31 , 32 is twice the drive frequency of the first through fourth horizontal scan circuits 11 - 14 of the first embodiment.
[0061] Based on the cycle of the supplied clock, the first horizontal scan circuit 31 turns ΦH 1 , ΦH 3 and ΦH 5 high in succession and the second horizontal scan circuit 32 turns ΦH 2 , ΦH 4 and ΦH 6 high in succession, so that readout can be performed at the same timing as that of the first embodiment described above.
[0062] (Third Embodiment)
[0063] A description will now be given of a third embodiment of the present invention, with reference to the accompanying drawings.
[0064] [0064]FIG. 5 is a schematic diagram of the structure of an image sensing apparatus according to a third embodiment of the present invention. FIG. 5 shows an arrangement in which the signal lines 101 - 104 depicted in FIG. 1 and FIG. 3 output to left and right lateral directions from a center thereof. It should be noted that, in FIG. 5, structures that are identical to those shown in FIGS. 1 and 3 are given identical reference numerals, and structures equivalent to those shown in FIGS. 1 and 3 but divided into lateral arrangements are given reference numerals followed by the reference symbol R (right) or L (left), as appropriate. Also, as can be appreciated by those of ordinary skill in the art, the structure shown in FIG. 5 can be easily adapted to the image sensing apparatus of the first embodiment described above.
[0065] (Fourth Embodiment)
[0066] Next, a description is given of a still camera image forming system using the image sensing apparatus described in the first, second and third embodiments described above, with reference to FIG. 10.
[0067] [0067]FIG. 10 is a block diagram showing the structure of an image-forming system according to a fourth embodiment of the present invention. In FIG. 10, reference numeral 401 denotes a barrier that functions as a lens protector and as a main switch. Reference numeral 402 denotes a lens that focuses an optical image of a subject at the image sensing apparatus 404 . Reference numeral 403 denotes an aperture for controlling the amount of light that passes through the lens 402 . Reference numeral 404 denotes an image sensing apparatus (corresponding to the image sensing apparatus described above in the first, second and third embodiments) for handling the subject optical image formed by the lens 402 as an image signal. Reference numeral 405 denotes an image signal processing circuit that includes a gain variable amplifier for amplifying image signals output from the image sensing apparatus 404 and a gain correction circuit for correcting the gain. Reference numeral 406 denotes an A/D converter for converting the analog image signals output by the image sensing apparatus 404 into digital signals. Reference numeral 407 denotes a signal processor for applying a variety of corrections and compression to image data output from the A/D converter 406 . Reference numeral 408 denotes a timing generator for outputting timing signals to the image sensing apparatus 404 , the image signal processing circuit 405 , the A/D converter 406 and the signal processor 407 . Reference numeral 409 denotes a controller/calculator for exerting overall controlling of various calculations and of the still video camera as a whole. Reference numeral 410 denotes a memory for temporarily storing image data. Reference numeral 411 denotes a recording medium control interface for recording on and reading from a recording medium. Reference numeral 412 denotes a semiconductor memory or other detachable recording medium for recording and/or providing image data. Reference numeral 413 denotes an external interface for communicating with an external computer or the like.
[0068] Next, a description is given of the operation of the still video camera having the structure described above during image sensing operation.
[0069] When the barrier 401 is opened, the main power switch is turned ON, the control system power is turned ON, and further, the power to the image forming system circuitry such as the A/D converter is turned ON.
[0070] Then, in order to control the amount of exposure light, the controller/calculator 409 opens the aperture 403 and signals output from the image sensing apparatus 404 are converted from analog signals into digital signals by the A/D converter 406 , after which the digital signals are input to the signal processor 407 . The controller/calculator 409 gauges the amount of light involved by using data that has undergone predetermined processes by the signal processor 407 , determines the brightness and calculates the exposure. The aperture 403 is then adjusted according to the exposure thus obtained.
[0071] Next, the controller/calculator 409 uses the signals output from the image sensing apparatus 404 to extract a high-frequency component and calculate the distance to the subject. The controller/calculator 409 then drives the lens and determines if the subject is in focus and, if the subject is not in focus, drives the lens again and measures the distance to the subject. Exposure commences once proper focus is achieved.
[0072] When exposure is completed, the image signals output from the image sensing apparatus 404 are A/D converted by the A/D converter 406 and written to the memory 410 via the signal processor 407 under the control of the controller/calculator 409 .
[0073] Thereafter, the controller/calculator 409 writes the data accumulated in the memory 410 to the removable recording medium 412 via the recording medium controller I/F 411 .
[0074] Or, the controller/calculator 409 may input the data accumulated in the memory 410 directly to the computer for image processing via the external I/F 413 .
[0075] (Other Embodiments)
[0076] A description is now given of other and further variations of the embodiments of the present invention, with reference to FIGS. 6, 7, 8 and 9 .
[0077] [0077]FIG. 6 is a diagram of the structure of an image sensing apparatus according to a first variation of the present invention. FIG. 7 is a diagram of the structure of an image sensing apparatus according to a second variation of the present invention. FIG. 8 is a diagram of the structure of an image sensing apparatus according to a third variation of the present invention. FIG. 9 is a diagram of the structure of an image sensing apparatus according to a fourth variation of the present invention.
[0078] In the first, second and third embodiments described above, Bayer arrangement color filters are used, the four signal readout systems (the differential amplifiers 15 - 18 , and the signal wires 101 - 104 which connects between capacitors CTN, CTS and the differential amplifiers 15 - 18 ) and two multiplexers 19 and 20 are used to obtain two outputs. However, as can be appreciated by those of ordinary skill in the art, the present invention is not limited to such arrangements, as is indicated by FIGS. 6 - 9 . Thus, for example, the signal readout components may be constituted so as to comprise six systems (as depicted in FIG. 6) or even eight systems (as in FIG. 7). In such cases, even if the readout speed at the signal readout components does not change compared to a case in which one system is used, the sensor signal output rate can be increased three- and four-fold, respectively. In addition, by providing a horizontal scan circuit on each signal readout component, the clock frequency used at the horizontal scan circuit can be reduced to ⅓ or ¼ compared to a case in which a single horizontal scan circuit is used for multiple signal readout components.
[0079] In addition, the color arrangement of the color filter can be changed as needed, provided that the number of signal readout systems is at least twice the maximum number of colors of the color filters covering the pixels included in the lines. For example, if the color filter has a layout that repeats the sequence R,G,B in every line, a signal readout components arrangement comprising at least six systems may be used (FIG. 8).
[0080] In addition, the color filter need not be limited to the primary colors. Instead, a complementary color filter may be used (see FIG. 9).
[0081] The present invention is not limited to the above-described embodiments, and various changes and modifications can be made within the spirit and scope of the present invention. Therefore, in order to apprise the public of the scope of the present invention, the following claims are made.
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An image sensing apparatus includes a photoelectric converter having a plurality of pixels covered by a color filter composed of a plurality of colors, a plurality of common readout units adapted to sequentially output signals from the plurality of pixels, a time division multiplex (TDM) unit for time division multiplexing signals from the plurality of common readout units, and a readout control unit for reading the signals from the plurality of pixels to the common readout units in such a way that signals from pixels covered by color filters of the same color are continuously multiplexed.
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CROSS-REFERENCES TO RELATED APPLICATIONS
This application claims the benefit of the U.S. Provisional Applications in the following table, all of which are hereby incorporated by reference:
U.S. PROVISIONAL APPLICATIONS
Serial
T&K #
Number
Title
Filing Date
TN 1599
60/177,999
Toroidal Choke Inductor for
Jan. 24, 2000
Wireless Communication and
Control
TH 1599x
60/186,376
Toroidal Choke Inductor for
Mar. 2, 2000
Wireless Communication and
Control
TH 1600
60/178,000
Ferromagnetic Choke in
Jan. 24, 2000
Wellhead
TH 1600x
60/186,380
Ferromagnetic Choke in
Mar. 2, 2000
Wellhead
TH 1601
60/186,505
Reservoir Production
Mar. 2, 2000
Control from Intelligent
Well Data
TH 1602
60/178,001
Controllable Gas-Lift Well
Jan. 24, 2000
and Valve
TH-1603
60/177,883
Permanent, Downhole,
Jan. 24, 2000
Wireless, Two-Way
Telemetry Backbone Using
Redundant Repeater, Spread
Spectrum Arrays
TH 1668
60/177,998
Petroleum Well Having
Jan. 24 2000
Downhole Sensors,
Communication, and Power
TH 1669
60/177,997
System and Method for Fluid
Jan. 24, 2000
Flow Optimization
TS6185
60/181,322
Optimal Predistortion in
Feb. 9, 2000
Downhole Communications
System
TH 1671
60/186,504
Tracer Injection in a
Mar. 2, 2000
Production Well
TH 1672
60/186,379
Oilwell Casing Electrical
Mar. 2, 2000
Power Pick-Off Points
TH 1673
60/186,394
Controllable Production
Mar. 2, 2000
Well Packer
TH 1674
60/186,382
Use of Downhole High
Mar. 2, 2000
Pressure Gas in a Gas Lift
Well
TH 1675
60/186,503
Wireless Smart Well Casing
Mar. 2, 2000
TH 1677
60/186,527
Method for Downhole Power
Mar. 2, 2000
Management Using
Energization from
Distributed Batteries or
Capacitors with
Reconfigurable Discharge
TH 1679
60/186,393
Wireless Downhole Well
Mar. 2, 2000
Interval Inflow and
Injection Control
TH 1681
60/186,394
Focused Through-Casing
Mar. 2, 2000
Resistivity Measurement
TH 1704
60/186,531
Downhole Rotary Hydraulic
Mar. 2, 2000
Pressure for Valve
Actuation
TH 1705
60/186,377
Wireless Downhole
Mar. 2, 2000
Measurement and Control For
Optimizing Gas Lift Well
and Field Performance
TH 1722
60/186,381
Controlled Downhole
Mar. 2, 2000
Chemical Injection
TH 1723
60/186,378
Wireless Power and
Mar. 2, 2000
Communications Cross-Bar
Switch
The current application shares some specification and figures with the following commonly owned and concurrently filed applications in the following table, all of which are hereby incorporated by reference:
COMMONLY OWNED AND CONCURRENTLY
FILED U.S. PATENT APPLICATIONS
Serial
T&K #
Number
Title
Filing Date
TH 1599ff
09/769,047
Choke Inductor for Wireless
Jan. 24, 2001
Communications and Control
TH 1600ff
09/769,048
Induction Choke for Power
Jan. 24, 2001
Distribution in Piping
Structure
TH 1603ff
09/768,655
Permanent Downhole,
Jan. 24, 2001
Wireless, Two-Way
Telemetry Backbone Using
Redundant Repeater
TH 1668ff
09/769,046
Petroleum Well Having
Jan. 24, 2001
Downhole Sensors,
Communication, and Power
TH 1669ff
09/768,656
System and Method for Fluid
Jan. 24, 2001
Flow Optimization
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a gas-lift well having a controllable gas-lift valve, and in particular, to a controllable gas-lift valve which communicates with the surface and is powered using the tubing string and casing as the conductor.
2. Description of Related Art
Gas-lift wells have been in use since the 1800's and have proven particularly useful in increasing efficient rates of oil production where the reservoir natural lift is insufficient (see Brown, Connolizo and Robertson, West Texas Oil Lifting Short Course and H. W. Winkler, Misunderstood or Overlooked Gas - lift Design and Equipment Considerations , SPE, p. 351 (1994)). Typically, in a gas-lift oil well, natural gas produced in the oil field is compressed and injected in an annular space between the casing and tubing and is directed from the casing into the tubing to provide a “lift” to the tubing fluid column for production of oil out of the tubing. Although the tubing can be used for the injection of the lift-gas and the annular space used to produce the oil, this is rare in practice. Initially, the gas-lift wells simply injected the gas at the bottom of the tubing, but with deep wells this requires excessively high kick off pressures. Later, methods were devised to inject the gas into the tubing at various depths in the wells to avoid some of the problems associated with high kick off pressures (see U.S. Pat. No. 5,267,469).
The most common type of gas-lift well uses mechanical, bellows-type gas-lift valves attached to the tubing to regulate the flow of gas from the annular space into the tubing string (see U.S. Pat. Nos. 5,782,261 and 5,425,425). In a typical bellows-type gas-lift valve, the bellows is preset or pre-charged to a certain pressure such that the valve permits communication of gas out of the annular space and into the tubing at the pre-charged pressure. The pressure charge of each valve is selected by a well engineer depending upon the position of the valve in the well, the pressure head, the physical conditions of the well downhole, and a variety of other factors, some of which are assumed or unknown, or will change over the production life of the well.
Referring to FIG. 1 in the drawings, a typical bellows-type gas-lift valve 310 has a pre-charge cylinder 312 , a metal bellows 314 , and entry ports 316 for communicating gas from the annular space outside the tubing string. Gas-lift valve 310 also includes a ball 318 that sealingly engages a valve seat 319 when valve 310 is in a closed position. When gas-lift valve 310 is in an open position, ball 318 no longer engages valve seat 319 , thereby allowing gas from the annular space to pass through entry port 316 , past ball 318 , and through exit port 320 . Several problems are common with bellows-type gas-lift valves. First, the bellows often loses its pre-charge, causing the valve to fail in the closed position or changing its setpoint to operate at other than the design goal, and exposure to overpressure causes similar problems. Another common failure is erosion around valve seat 319 and deterioration of the ball stem in the valve. This leads to partial failure of the valve or at least inefficient production. Because the gas flow through a gas-lift valve is often not continuous at a steady state, but rather exhibits a certain amount of hammer and chatter as ball 318 rapidly opens and closes, ball and valve seat degradation are common, leading to valve leakage. Failure or inefficient operation of bellows-type valves leads to corresponding inefficiencies in operation of a typical gas-lift well. In fact, it is estimated that well production is at least 5-15% less than optimum because of valve failure or operational inefficiencies. Fundamentally these difficulties are caused by the present inability to monitor, control, or prevent instabilities, since the valve characteristics are set at design time, and even without failure they cannot be easily changed after the valve is installed in the well.
Side-pocket mandrels coupled to the tubing string are known for receiving wireline insertable and retrievable gas-lift valves. Many gas-lift wells have gas-lift valves incorporated as an integral part of the tubing string, typically mounted to a pipe section. However, wireline replaceable side pocket mandrel type of gas-lift valves have many advantages and are quite commonly used (see U.S. Pat. Nos. 5,782,261 and 5,797,453). Gas-lift valves placed in a side pocket mandrel can be inserted and removed using a wireline and workover tool either in top or bottom entry. In lateral and horizontal boreholes, coiled tubing is used for insertion and removal of the gas-lift valves. It is common practice in oilfield production to shut off production of the well periodically and use a wireline to replace gas-lift valves. However, an operator often does not have a good estimate of which valves in the well have failed or degraded and need to be replaced.
It would, therefore, be a significant advantage if a system and method were devised which overcame the inefficiency of conventional bellows-type gas-lift valves. Several methods have been devised to place controllable valves downhole on the tubing string but all such known devices typically use an electrical cable or hydraulic line disposed along the tubing string to power and communicate with the gas-lift valves. It is, of course, highly undesirable and in practice difficult to use a cable along the tubing string either integral with the tubing string or spaced in the annulus between the tubing string and the casing because of the number of failure mechanisms present in such a system. The use of a cable presents difficulties for well operators while assembling and inserting the tubing string into a borehole. Additionally, the cable is subjected to corrosion and heavy wear due to movement of the tubing string within the borehole. An example of a downhole communication system using a cable is shown in PCT/EP97/01621.
U.S. Pat. No. 4,839,644 describes a method and system for wireless two-way communications in a cased borehole having a tubing string. However, this system describes a communication scheme for coupling electromagnetic energy in a transverse electric mode (TEM) using the annulus between the casing and the tubing. The system requires a toroidal antenna to launch or receive in a TEM mode, and the patent suggests an insulated wellhead. The inductive coupling of the system requires a substantially nonconductive fluid such as crude oil in the annulus between the casing and the tubing, and this oil must be of a higher density that brine so that leaked brine does not gather at the bottom of the annulus. This system does not speak to the issue of providing power to the downhole module. The invention described in U.S. Pat. No. 4,839,644 has not been widely adopted as a practical scheme for downhole two-way communication because it is expensive, has problems with brine leakage into the casing, and is difficult to use. Another system for downhole communication using mud pulse telemetry is described in U.S. Pat. Nos. 4,648,471 and 5,887,657. Although mud pulse telemetry can be successful at low data rates, it is of limited usefulness where high data rates are required or where it is undesirable to have complex, mud pulse telemetry equipment downhole. Other methods of communicating within a borehole are described in U.S. Pat. Nos. 4,468,665; 4,578,675; 4,739,325; 5,130,706; 5,467,083; 5,493,288; 5,574,374; 5,576,703; and 5,883,516.
It would, therefore, be a significant advance in the operation of gas-lift wells if an alternative to the conventional bellows type valve were provided, in particular, if the tubing string and the casing could be used as the communication and power conductors to control and operate a controllable gas-lift valve.
All references cited herein are incorporated by reference to the maximum extent allowable by law. To the extent a reference may not be fully incorporated herein, it is incorporated by reference for background purposes and indicative of the knowledge of one of ordinary skill in the art.
SUMMARY OF THE INVENTION
The problems outlined above are largely solved by the electrically controllable gas-lift well in accordance with the present invention. Broadly speaking, the controllable gas-lift well includes a cased wellbore having a tubing string positioned and longitudinally extending within the casing. The position of the tubing string within the casing creates an annulus between the tubing string and the casing. A controllable gas-lift valve is coupled to the tubing to control gas injection between the interior and exterior of the tubing, more specifically, between the annulus and the interior of the tubing. The controllable gas-lift valve is powered and controlled from the surface to regulate the fluid communication between the annulus and the interior of the tubing. Communication signals and power are sent from the surface using the tubing and casing as conductors. The power is preferably a low voltage AC at conventional power frequencies in the range 50 to 400 Hertz, but in certain embodiments DC power may also be used.
In more detail, a surface computer having a modem imparts a communication signal to the tubing, and the signal is received by a modem downhole connected to the controllable gas-lift valve. Similarly, the modem downhole can communicate sensor information to the surface computer. Further, power is input into the tubing string and received downhole to control the operation of the controllable gas-lift valve. Preferably, the casing is used as the ground return conductor. Alternatively, a distant ground may be used as the electrical return. In a preferred embodiment, the controllable gas-lift valve includes a motor which operates to insert and withdraw a cage trim valve from a seat, regulating the gas injection between the annulus and the interior of the tubing, or other means for controlling gas flow rate.
In enhanced forms, the controllable gas-lift well includes one or more sensors downhole which are preferably in contact with the downhole modem and communicate with the surface computer, although downhole processing may also be used to minimize required communications data rate, or even to make the downhole system autonomous. Such sensors as temperature, pressure, hydrophone, microphone, geophone, valve position, flow rates, and differential pressure gauges are advantageously used in many situations. The sensors supply measurements to the modem for transmission to the surface or directly to a programmable interface controller operating the controllable gas-lift valve for controlling the fluid flow through the gas-lift valve.
Preferably, ferromagnetic chokes are coupled to the tubing to act as a series impedance to current flow on the tubing. In a preferred form, an upper ferromagnetic choke is placed around the tubing below the tubing hanger, and the current and communication signals are imparted to the tubing below the upper ferromagnetic choke. A lower ferromagnetic choke is placed downhole around the tubing with the controllable gas-lift valve electrically coupled to the tubing above the lower ferromagnetic choke, although the controllable gas-lift valve may be mechanically coupled to the tubing below the lower ferromagnetic choke. It is desirable to mechanically place the operating controllable gas-lift valve below the lower ferromagnetic choke so that the borehole fluid level is below the choke.
Preferably, a surface controller (computer) is coupled via a surface master modem and the tubing to the downhole slave modem of the controllable gas-lift valve. The surface computer can receive measurements from a variety of sources, such as downhole and surface sensors, measurements of the oil output, and measurements of the compressed gas input to the well (flow and pressure). Using such measurements, the computer can compute an optimum position of the controllable gas-lift valve, more particularly, the optimum amount of the gas injected from the annulus inside the casing through the controllable valve into the tubing. Additional enhancements are possible, such as controlling the amount of compressed gas input into the well at the surface, controlling back pressure on the wells, controlling a porous frit or surfactant injection system to foam the oil, and receiving production and operation measurements from a variety of other wells in the same field to optimize the production of the field.
The ability to actively monitor current conditions downhole, coupled with the ability to control surface and downhole conditions, has many advantages in a gas-lift well.
Gas-lift wells have four broad regimes of fluid flow, for example bubbly, Taylor, slug and annular flow. The downhole sensors of the present invention enable the detection of flow regime. The above referenced control mechanisms-surface computer, controllable valves, gas input, surfactant injection, etc.—provide the ability to attain and maintain the desired flow regime. In general, well tests and diagnostics can be performed and analyzed continuously and in near real time.
In one embodiment, all of the gas-lift valves in the well are of the controllable type in accordance with the present invention. It is desirable to lift the oil column from a point in the borehole as close as possible to the production packer. That is, the lowest gas-lift valve is the primary valve in production. The upper gas-lift valves are used for annular unloading of the well during production initiation. In conventional gas-lift wells, these upper valves have bellows pre-set with a margin of error to ensure the valves close after unloading. This means operating pressures that permit closing of unloading valves as each successive valve is uncovered. These margins result in the inability to use the full available pressure to lift at maximum depth during production: lift pressure is lost downhole to accommodate the design margin offset at each valve. Further, such conventional valves often leak and fail to fully close. Use of the controllable valves of the present invention overcomes such shortcomings.
In an alternate embodiment, a number of conventional mechanical bellows-type gas-lift valves are longitudinally spaced on the tubing string in a conventional manner. The lower-most valve is preferably a bellows-type valve which aids in unloading of the well in the normal manner. The bellows-type valve's pre-charged pressure is set normally. That is, the unloading pushes annular fluid into the tubing through successively deeper gas-lift valves until the next to the last gas-lift valve is cleared by the fluid column. Production is then maintained by gas injection through a controllable gas-lift valve located on the tubing string, which as outlined above receives power and communication signals through its connection to the tubing and a grounding centralizer. While only one controllable gas-lift valve is described, more can be used if desired, depending upon the characteristics of a particular well. If the controllable gas-lift valve fails, the production is diverted through the lowest manual valve above the controllable gas-lift valve.
Construction of such a controllable gas-lift well is designed to be as similar to conventional construction methodology as possible. That is, after casing the well, a packer is typically set above the production zone. The tubing string is then fed through the casing into communication with the production zone. As the tubing string is made up at the surface, a lower ferromagnetic choke is placed around one of the conventional tubing string sections for positioning above the bottom valve, or a pre-assembled joint prepared with the valve, electronics module, and choke may be be used. In the sections of the tubing string where it is desired, a gas-lift valve is coupled to the string. In a preferred form the downhole valve is tubing conveyed, but a side pocket mandrel for receiving a slickline insertable and retrievable gas-lift valve may also be used. With the side-pocket mandrel, either a controllable gas-lift valve in accordance with the present invention can be inserted, or a conventional bellows-type valve can be used. The tubing string is made up to the surface, where a ferromagnetic choke or other electrical isolation device such as an electrically insulating joint is again placed around the tubing string below the tubing hanger. Communication and power leads are then connected through the wellhead feed through to the tubing string below the upper ferromagnetic choke or other isolation device.
In an alternative form of the controllable gas lift well, a pod having only a sensor and communication device is inserted without the necessity of including a controllable gas-lift valve in every pod. That is, an electronics module having pressure, temperature or acoustic sensors or other sensors, a power supply, and a modem may be tubing conveyed or inserted into a side pocket mandrel for communication to the surface computer or with other downhole modules and controllable gas lift valves using the tubing and casing as conductors. Alternatively, such electronics modules may be mounted directly on the tubing (tubing conveyed) and not be configured to be wireline replaceable. If directly mounted to the tubing an electronic module or a controllable gas-lift valve may only be replaced by pulling the entire tubing string. In an alternative form, the controllable valve can have its separate control, power and wireless communication electronics mounted in the side pocket mandrel of the tubing and not in the wireline replaceable valve. In the preferred form, the electronics are integral and replaceable along with the gas-lift valve. In another form, the high permeability magnetic chokes may be replaced by electrically insulated tubing sections. Further, an insulated tubing hanger in the wellhead may replace the upper choke or such upper insulating tubing sections.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional front view of a prior art, bellows-type gas-lift valve.
FIG. 2 is a schematic front view of a controllable gas-lift well according to one embodiment of the present invention, the gas-lift well having a tubing string and a casing positioned within a borehole.
FIG. 3 is a schematic front view of the tubing string and casing of FIG. 2, the tubing string having side pocket mandrels positioned thereon.
FIG. 4A is an enlarged schematic front view of the side pocket mandrel of FIG. 3 and a controllable gas-lift valve, the valve having an internal electronics module and being wireline retrievable from the side pocket mandrel.
FIG. 4B is a cross-sectional side view of the controllable gas-lift valve of FIG. 4A taken at IV—IV.
FIGS. 5A-5C are cross-sectional front views of a controllable valve in a cage configuration according to one embodiment of the present invention.
FIG. 6 is an enlarged schematic front view of the tubing string and casing of FIG. 2, the tubing string having an electronics module, sensors, and a controllable gas-lift valve operatively connected to an exterior of the tubing string.
FIG. 7 is an enlarged schematic front view of the tubing string and casing of FIG. 2, the tubing string having a controllable gas-lift valve permanently connected to the tubing string.
FIG. 8 is a cross sectional side views of the controllable gas-lift valve of FIG. 7 taken at VIII—VIII.
FIG. 9 is a schematic of an equivalent circuit diagram for the controllable gas-lift well of FIG. 2, the gas-lift well having an AC power source, the electronics module of FIG. 4, and the electronics module of FIG. 6 .
FIG. 10 is a schematic diagram depicting a surface computer electrically coupled to an electronics module of the gas-lift well of FIG. 2 .
FIG. 11 is a system block diagram of the electronics module of FIG. 10 .
FIG. 12 illustrates a disposition of chokes and controllable gas-lift valves to provide control of the valves when the tubing-casing annulus is partially filled with conductive fluid. and
FIG. 13 depicts a time-series chart showing the relationships between degree of opening of a gas-lift valve, annulus pressure, tubing pressure, and lifted fluid flow regimes.
DETAILED DESCRIPTION OF THE INVENTION
As used in the present application, a “valve” is any device that functions to regulate the flow of a fluid. Examples of valves include, but are not limited to, bellows-type gas-lift valves and controllable gas-lift valves, each of which may be used to regulate the flow of lift gas into a tubing string of a well. The internal workings of valves can vary greatly, and in the present application, it is not intended to limit the valves described to any particular configuration, so long as the valve functions to regulate flow. Some of the various types of flow regulating mechanisms include, but are not limited to, ball valve configurations, needle valve configurations, gate valve configurations, and cage valve configurations. The methods of installation for valves discussed in the present application can vary widely. Valves can be mounted downhole in a well in many different ways, some of which include tubing conveyed mounting configurations, side-pocket mandrel configurations, or permanent mounting configurations such as mounting the valve in an enlarged tubing pod.
The term “modem” is used generically herein to refer to any communications device for transmitting and/or receiving electrical communication signals via an electrical conductor (e.g., metal). Hence, the term is not limited to the acronym for a modulator (device that converts a voice or data signal into a form that can be transmitted)/demodulator (a device that recovers an original signal after it has modulated a high frequency carrier). Also, the term “modem” as used herein is not limited to conventional computer modems that convert digital signals to analog signals and vice versa (e.g., to send digital data signals over the analog Public Switched Telephone Network). For example, if a sensor outputs measurements in an analog format, then such measurements may only need to modulate a carrier to be transmitted-hence no analog-to-digital conversion is needed. As another example, a relay/slave modem or communication device may only need to identify, filter, amplify, and/or retransmit a signal received.
The term “sensor” as used in the present application refers to any device that detects, determines, monitors, records, or otherwise senses the absolute value of or a change in a physical quantity. Sensors as described in the present application can be used to measure temperature, pressure (both absolute and differential), flow rate, seismic data, acoustic data, pH level, salinity levels, valve positions, or almost any other physical data.
The term “electronics module” in the present application refers to a control device. Electronics modules can exist in many configurations and can be mounted downhole in many different ways. In one mounting configuration, the electronics module is actually located within a valve and provides control for the operation of a motor within the valve. Electronics modules can also be mounted external to any particular valve. Some electronics modules will be mounted within side pocket mandrels or enlarged tubing pockets, while others may be permanently attached to the tubing string. Electronics modules often are electrically connected to sensors and assist in relaying sensor information to the surface of the well. It is conceivable that the sensors associated with a particular electronics module may even be packaged within the electronics module. Finally, the electronics module is often closely associated with, and may actually contain, a modem for receiving, sending, and relaying communications from and to the surface of the well. Signals that are received from the surface by the electronics module are often used to effect changes within downhole controllable devices, such as valves. Signals sent or relayed to the surface by the electronics module generally contain information about downhole physical conditions supplied by the sensors.
The terms “first end” and “second end” as used herein are defined generally to call out a side or portion of a piping structure, which may or may not encompass the most proximate locations, as well as intermediate locations along a called out side or portion of the piping structure. Similarly, in accordance with conventional terminology of oilfield practice, the descriptors “upper”, “lower”, “uphole” and “downhole” refer to distance along hole depth from the surface, which in deviated wells may or may not accord with absolute vertical placement measured with reference to the ground surface.
Referring to FIG. 2 in the drawings, a petroleum well according to the present invention is illustrated. The petroleum well is a gas-lift well 210 having a borehole 211 extending from a surface 212 into a production zone 214 that is located downhole. A production platform is located at surface 212 and includes a hanger 22 for supporting a casing 24 and a tubing string 26 . Casing 24 is of the type conventionally employed in the oil and gas industry. The casing 24 is typically installed in sections and is cemented in the borehole during well completion. Tubing string 26 , also referred to as production tubing, is generally a conventional string comprising a plurality of elongated tubular pipe sections joined by threaded couplings at each end of the pipe sections, but may alternatively be continuously inserted as coiled tubing for example. The production platform includes a gas input throttle 30 to control the input of compressed gas into an annular space 31 between casing 24 and tubing string 26 . Conversely, output valve 32 permits the expulsion of oil and gas bubbles from the interior of tubing string 26 during oil production.
An upper ferromagnetic choke 40 or insulating pipe joint, and a lower ferromagnetic choke 42 are installed on tubing string 26 to act as a series impedance to electric current flow. The size and material of ferromagnetic chokes 40 , 42 can be altered to vary the series impedance value. The section of tubing string 26 between upper choke 40 and lower choke 42 may be viewed as a power and communications path (see also FIG. 9 ). Both upper and lower chokes 40 , 42 are manufactured of high permeability magnetic material and are mounted concentric and external to tubing string 26 . Chokes 40 , 42 are typically insulated with shrink wrap plastic and encased with fiber-reinforced epoxy to withstand rough handling.
A computer and power source 44 having power and communication feeds 46 is disposed outside of borehole 211 at surface 212 . Communication feeds 46 pass through a pressure feed 47 located in hanger 22 and are electrically coupled to tubing string 26 below upper choke 40 . Power and communications signals are supplied to tubing string 26 from computer and power source 44 .
A packer 48 is placed within casing 24 downhole below lower choke 42 . Packer 48 is located above production zone 214 and serves to isolate production zone 214 and to electrically connect metal tubing string 26 to metal casing 24 . Similarly, above surface 212 , the metal hanger 22 (along with the surface valves, platform, and other production equipment) electrically connects metal tubing string 26 to metal casing 24 . Typically, the electrical connections between tubing string 26 and casing 24 would not allow electrical signals to be transmitted or received up and down borehole 211 using tubing string 26 as one conductor and casing 24 as another conductor. However, the disposition of upper and lower ferromagnetic chokes 40 , 42 around tubing string 26 alter the electrical characteristics of tubing 26 , providing a system and method to provide power and communication signals up and down borehole 211 of gas-lift well 210 .
A plurality of conventional bellows-type gas-lift valves 50 are operatively connected to tubing string 26 (see discussion of FIG. 1 in the Background of the Invention). The number of conventional valves 50 disposed along tubing string 26 depends upon the depth of the well and the well lift characteristics. A controllable gas-lift valve 52 in accordance with the present invention is attached to tubing string 26 as the penultimate gas-lift valve. In this embodiment, only one controllable gas-lift valve 52 is used.
Referring now to FIG. 3 in the drawings, the downhole configuration of bellows-type valve 50 and controllable valve 52 , as well as the electrical connections with casing 24 and tubing string 26 , is depicted. The pipe sections of tubing string 26 are conventional and where it is desired to incorporate a gas-lift valve in a particular pipe section, a side pocket mandrel 54 , commonly available in the industry, is employed. Each side pocket mandrel 54 is a non-concentric enlargement of tubing string 26 that permits wireline retrieval and insertion of either bellows-type valves 50 or controllable valves 52 downhole.
Referring still to FIG. 3, but also to FIGS. 4A and 4B, a plurality of bow spring centralizers 60 may be installed at various locations along the length of tubing string 26 to center tubing string 26 relative to casing 24 . When located between upper and lower chokes 40 , 42 , each bow spring centralizer 60 includes insulators 62 to electrically isolate casing 24 from tubing string 26 . A power and signal jumper wire 64 electrically connects controllable valve 52 to tubing string 26 at a point between upper choke 40 and lower choke 42 . Although controllable valve 52 is shown below lower choke 42 , the valve 52 could be disposed above lower choke 42 such that controllable valve 52 is electrically coupled to tubing string 26 without using a power jumper. A ground wire 66 provides a return path from controllable valve 52 to casing 24 via electrically conductive centralizer 60 . While jumper wire 64 and ground wire 66 are illustrated schematically in FIGS. 3 and 4A, it will be appreciated that in commercial use jumper wire 64 and ground wire 66 may be insulated and predominantly integral to a housing of side pocket mandrel 54 .
It should be noted that the power supplied downhole through tubing string 26 is effective only when annulus 31 does not contain an electrically conductive liquid between upper choke 40 and lower choke 42 . If an electrically conductive liquid is present in the annulus 31 between the chokes 40 , 42 , the liquid will cause a short circuit of the current in tubing string 26 to casing 24 .
Use of controllable valves 52 may be preferable to use of conventional bellows valves for several reasons. For example, conventional bellows valves 50 (see FIG. 1) often leak when they should be closed during production, resulting in inefficient well operation. Additionally, conventional bellows valves 50 are usually designed to use sequentially decremented operating presssures resulting in the inability to make use of full available lift pressure, therefore resulting in further inefficiency.
Referring more specifically to FIGS. 4A and 4B, a more detailed illustration of controllable gas-lift valve 52 and side pocket mandrel 54 is provided. Side pocket mandrel 54 includes a housing 68 having a gas inlet port 72 and a gas outlet port 74 . When controllable valve 52 is in an open position, gas inlet port 72 and gas outlet port 74 provide fluid communication between annular space 31 and an interior of tubing string 26 . In a closed position, controllable valve 52 prevents fluid communication between annular space 31 and the interior of tubing string 26 . In a plurality of intermediate positions located between the open and closed positions, controllable valve 52 meters the amount of gas flowing from annular space 31 into tubing string 26 through gas inlet port 72 and gas outlet port 74 .
Controllable gas-lift valve 52 includes a generally cylindrical, hollow housing 80 configured for reception in side pocket mandrel 54 , and is furnished with a latching method to leave and retrieve the valve using a tubing accessible method such as slickline. An electronics module 82 is disposed within housing 80 and is electrically connected to a stepper motor 34 for controlling the operation thereof. Operation of stepper motor 84 adjusts a needle valve head 86 , thereby controlling the position of needle valve head 86 in relation to a valve seat 88 . Movement of needle valve head 86 by stepper motor 84 directly affects the amount of fluid communication that occurs between annular space 31 and the interior of tubing string 26 . When needle valve head 86 fully engages valve seat 88 as shown in FIG. 4B, the controllable valve 52 is in the closed position.
Seals 90 are made of an elastomeric material and allow controllable valve 52 to sealingly engage side pocket mandrel 54 . Slip rings 92 surround a lower portion of housing 80 and are electrically connected to electronics module 82 . Slip rings 92 provide an electrical connection for power and communication between tubing string 26 and electronics module 82 .
Controllable valve 52 includes a check valve head 94 disposed within housing 80 below needle valve head 86 . An inlet 96 and an outlet 98 cooperate with inlet port 72 and outlet port 74 when valve 52 is in the open position to provide fluid communication between annulus 31 and the interior of tubing string 26 . Check valve 94 insures that fluid flow only occurs when the pressure of fluid in annulus 31 is greater than the pressure of fluid in the interior of tubing string 26 .
Referring to FIGS. 5A, 5 B, and 5 C in the drawings, another embodiment of a controllable valve 220 according to the present invention is illustrated. Controllable valve 220 includes a housing 222 and is slidably received in a side pocket mandrel 224 (similar to side pocket mandrel 54 of FIG. 4 A). Side pocket mandrel 224 includes a housing 226 having a gas inlet port 228 and a gas outlet port 230 . When controllable valve 220 is in an open position, gas inlet port 228 and gas outlet port 230 provide fluid communication between annular space 31 and an interior of tubing string 26 . In a closed position, controllable valve 220 prevents fluid communication between annular space 31 and the interior of tubing string 26 . In a plurality of intermediate positions located between the open and closed positions, controllable valve 220 meters the amount of gas flowing from annular space 31 into tubing string 26 through gas inlet port 228 and gas outlet port 230 .
A motor 234 is disposed within housing 222 of controllable valve 220 for rotating shaft 236 . Pinion 236 engages a worm gear 238 , which in turn raises and lowers a cage 240 . When valve 220 is in the closed position, cage 240 engages a seat 242 to prevent flow into an orifice 244 , thereby preventing flow through valve 220 . As shown in more detail in FIG. 5B, a shoulder 246 on seat 242 is configured to sealingly engage a mating collar on cage 240 when the valve is closed. This “cage” valve configuration with symmetrically spaced and opposing flow ports is believed to be a preferable design since the impinging flow minimizes erosion when compared to the alternative embodiment of a needle valve configuration (see FIG. 4 B). More specifically, fluid flow from inlet port 228 , past the cage and seat juncture ( 240 , 242 ) permits precise fluid regulation without undue fluid wear on the mechanical interfaces.
Controllable valve 220 includes a check valve head 250 disposed within housing 222 below cage 240 . An inlet 252 and an outlet 254 cooperate with gas inlet port 228 and gas outlet port 230 when valve 220 is in the open position to provide fluid communication between annulus 31 and the interior of tubing string 26 . Check valve head 250 insures that fluid flow only occurs when the pressure of fluid in annulus 31 is greater than the pressure of fluid in the interior of tubing string 26 .
An electronics module 256 is disposed within the housing of controllable valve 220 . Electronics module is operatively connected to valve 220 for communication between the surface of the well and the valve. In addition to sending signals to the surface to communicate downhole physical conditions, the electronics module can receive instructions from the surface and adjust the operational characteristics of the valve 220 .
While FIGS. 4A, 4 B, and FIGS. 5A-5C illustrate the embodiments of the controllable valve in accordance with the present invention, other embodiments are possible without departing from the spirit and scope of the present invention. In particular, patent publication WO02/059457, entitled “Downhole Motorized Control Valve” describes yet another embodiment and is incorporated herein by reference. Referring to FIG. 6 in the drawings, an alternative installation configuration for a controllable valve assembly is shown and should be contrasted with the slide pocket mandrel configuration of FIG. 4 A. In FIG. 6, tubing 26 includes an annularly enlarged pocket, or pod 100 formed on the exterior of tubing string 26 . Enlarged pocket 100 includes a housing that surrounds and protects the controllable gas-lift valve assembly and an electronics module 106 . In this mounting configuration, gas-lift valve assembly is rigidly mounted to tubing string 26 and is not insertable and retrievable by wireline. A ground wire 102 (similar to ground wire 66 of FIG. 4A) is fed through enlarged pocket 100 to connect electronics module 106 to bow spring centralizer 60 , which is grounded to casing 24 . Electronics module 106 is rigidly connected to tubing string 26 and receives communications and power via a power and signal jumper 104 . The electronics module 106 in this configuration is not insertable or retrievable by wireline.
Enlarge pocket 100 includes a housing that surrounds and protects controllable the gas-lift valve assembly and an electronics module 106 . In this mounting configuration, gas-lift valve assembly is rigidly mounted to tubing string 26 and is not insertable and retrievable by wireline. A ground wire 102 (similar to ground wire 66 of FIG. 4A) is fed through enlarged pocket 100 to connect electronics module 106 to bow spring centralizer 60 , which is grounded to causing 24 . Electronics module 106 is rigidly connected to tubing string 26 and receives communications and power via a power and signal jumper 104 . The electronics module 106 in this configuration is not insertable or retrievable by wireline.
Controllable valve assembly includes a motorized cage valve 108 and a check valve 110 that are schematically illustrated in FIG. 6 . Cage valve 108 and check valve 110 operate in a similar fashion to cage 240 and check valve head 250 of FIG. 5 A. The valves 108 , 110 cooperate to control fluid communication between annular space 31 and the interior of tubing string 26 .
A plurality of sensors are used in conjunction with electronics module 106 to control the operation of controllable valve and gas-lift well 210 . Pressure sensors, such as those produced by Three Measurement Specialties, Inc., can be used to measure internal tubing pressure, internal pod housing pressures, and differential pressures across gas-lift valves. In commercial operation, the internal pod pressure is considered unnecessary. A pressure sensor 112 is rigidly mounted to tubing string 26 to sense the internal tubing pressure of fluid within tubing string 26 . A pressure sensor 118 is mounted within pocket 100 to determine the differential pressure across cage valve 108 . Both pressure sensor 112 and pressure sensor 118 are independently electrically coupled to electronics module 106 for receiving power and for relaying communications. Pressure sensors 112 , 118 are potted to withstand the severe vibration associated with gas-lift tubing strings.
Temperature sensors, such as those manufactured by Four Analog Devices, Inc. (e.g. LM-34), are used to measure the temperature of fluid within the tubing, housing pod, power transformer, or power supply. A temperature sensor 114 is mounted to tubing string 26 to sense the internal temperature of fluid within tubing string 26 . Temperature sensor 114 is electrically coupled to electronics module 106 for receiving power and for relaying communications. The temperature transducers used downhole are rated for −50 to 300° F. and are conditioned by input circuitry to +5 to +255° F. The raw voltage developed at a power supply in electronics module 106 is divided in a resistive divider element so that 25.5 volts will produce an input to the analog/digital converter of 5 volts.
A salinity sensor 116 is also electrically connected to electronics module 106 . Salinity sensor 116 is rigidly and sealingly connected to the housing of enlarged pocket 100 to sense the salinity of the fluid in annulus 31 .
It should be understood that the alternate embodiments illustrated in FIGS. 4A, 5 C and 6 could include or exclude any number of the sensors 112 , 114 , 116 or 118 . Sensors other than those displayed could also be employed in either of the embodiments. These could include gauge pressure sensors, absolute pressure sensors, differential pressure sensors, flow rate sensors, tubing acoustic wave sensors, valve position sensors, or a variety of other analog signal sensors. Similarly, it should be noted that while electronics module 82 shown in FIG. 4B is packaged within valve 52 , an electronics module similar to electronics module 106 could be packaged with various sensors and deployed independently of controllable valve 52 .
Referring to FIGS. 7 and 8 in the drawings, a controllable gas-lift valve 132 having a valve housing 133 is mounted on a tubing conveyed mandrel 134 . Controllable valve 132 is mounted similar to most of the bellows-type gas-lift valves that are in use today. These valves are not wireline replaceable, and must be replaced by pulling tubing string 26 . An electronics module 138 is mounted within housing 133 above a motor 142 that drives a needle valve head 144 . A check valve 146 is disposed within housing 133 below needle valve head 144 . Stepper motor 142 , needle valve head 144 , and check valve 146 are similar in operation and configuration to those used in controllable valve 52 depicted in FIG. 4 B. It should be understood, however, that valve 132 could include a cage configuration (as opposed to the needle valve configuration) similar to valve 220 of FIG. 5 A. In similar fashion to FIG. 4B, an inlet opening 148 and an outlet opening 150 are provided to provide a fluid communication path between annulus 31 and the interior of tubing string 26 .
Power and communications are supplied to electronics module 138 by a power and signal jumper 140 connected between electronics module 138 and housing 133 . Power is supplied to housing 133 either directly from tubing string 26 or via a wire (not shown) connected between housing 133 and tubing string 26 . A ground wire 136 couples electronics module 138 centralizer 60 for grounding purposes.
Although not specifically shown in the drawings, electronics module 138 could have any number of sensors electrically coupled to the module 138 for sensing downhole conditions. These could include pressure sensors, temperature sensors, salinity sensors, flow rate sensors, tubing acoustic wave sensors, valve position sensors, or a variety of other analog signal sensors. These sensors would likely be connected in a manner similar to that used for sensors 112 , 114 , 116 , and 118 of FIG. 6 .
Referring now to FIG. 9 in the drawings, an equivalent circuit diagram for gas-lift well 210 is illustrated and should be compared to FIG. 2 . Computer and power source 44 includes an AC power source 120 and a master modem 122 electrically connected between casing 24 and tubing string 26 . As discussed previously, electronics module 82 is mounted internally within a valve housing that is wireline insertable and retrievable downhole. Electronics module 106 is independently and permanently mounted in an enlarged pocket on tubing string 26 . Although not shown, the equivalent circuit diagram could also include depictions of electronics module 256 of FIG. 5A or electronic module 138 of FIG. 8 .
For purposes of the equivalent circuit diagram of FIG. 9, it is important to note that while electronics modules 82 , 106 appear identical, both modules 82 , 106 being electrically connected between casing 24 and tubing string 26 , electronics modules 82 , 106 may contain or omit different components and combinations such as sensors 112 , 114 , 116 , 118 . Additionally, the electronics modules may or may not be an integral part of the controllable valve. Each electronics module includes a power transformer 124 and a data transformer 128 . Data transformer 128 is electrically coupled to a slave modem 130 .
Referring to FIG. 10 in the drawings, a block diagram of a communications system 152 according to the present invention is illustrated. FIG. 10 should be compared and contrasted with FIGS. 2 and 9. Communications system 152 includes master modem 122 , AC power source 120 , and a computer 154 . Computer 154 is coupled to master modem 122 , preferably via an RS 232 bus, and runs a multitasking operating system such as Windows NT and a variety of user applications. AC power source 120 includes a 120 volt AC input 156 , a ground 158 , and a neutral 160 as illustrated. Power source 120 also includes a fuse 162 , preferably 7.5 amp, and has a transformer output 164 at approximately 6 volts AC and 60 Hz. Power source 120 and master modem 122 are both connected to casing 24 and tubing 26 .
Communications system 152 includes an electronics module 165 that is analogous to module 82 in FIG. 4B, module 256 in FIG. 5B, module 106 in FIG. 6, and module 138 in FIG. 8 . Electronics module 165 includes a power supply 166 and an analog-to-digital conversion module 168 . A programmable interface controller (PIC) 170 is electrically coupled to a slave modem 171 (analogous to slave modem 130 of FIG. 9 ). Couplings 172 are provided for coupling electronics module 165 to casing 24 and tubing 26 .
Referring to FIG. 11 in the drawings, electronics module 165 is illustrated in more detail. Amplifiers and signal conditioners 180 are provided for receiving inputs from a variety of sensors such as tubing temperature, annulus temperature, tubing pressure, annulus pressure, lift gas flow rate, valve position, salinity, differential pressure, acoustic readings, and others. Some of these sensors are analogous to sensors 112 , 114 , 116 , and 118 shown in FIG. 6 . Preferably, any low noise operational amplifiers are configured with non-inverting single ended inputs (e.g. Linear Technology LT1369). All amplifiers 180 are programmed with gain elements designed to convert the operating range of an individual sensor input to a meaningful 8 bit output. For example, one psi of pressure input would produce one bit of digital output, 100 degrees of temperature will produce 100 bits of digital output, and 12.3 volts of raw DC voltage input will produce an output of 123 bits. Amplifiers 180 are capable of rail-to-rail operation.
Electronics module 165 is electrically connected to master modem 122 via casing 24 and tubing string 26 . Address switches 182 are provided to address a particular device from master modem 122 . As shown in FIG. 11, 4 bits of addresses are switch selectable to form the upper 4 bits of a full 8 bit address. The lower 4 bits are implied and are used to address the individual elements within each electronics module 165 . Thus, using the configuration illustrated, sixteen modules are assigned to a single master modem 122 on a single communications line. As configured, up to four master modems 122 can be accommodated on a single communications line.
Electronics module 165 also includes PIC 170 , which preferably has a basic clock speed of 20 MHz and is configured with 8 analog-to-digital inputs 184 and 4 address inputs 186 . PIC 170 includes a TTL level serial communications UART 188 , as well as a motor controller interface 190 .
Electronics module 165 also contains a power supply 166 . A nominal 6 volts AC line power is supplied to power supply 166 along tubing string 26 . Power supply 166 converts this power to plus 5 volts DC at terminal 192 , minus 5 volts DC at terminal 194 , and plus 6 volts DC at terminal 196 . A ground terminal 198 is also shown. The converted power is used by various elements within electronics module 165 .
Although connections between power supply 166 and the components of electronics module 165 are not shown, the power supply 166 is electrically coupled to the following components to provide the specified power. PIC 170 uses plus 5 volts DC, while slave modem 171 uses plus 5 and minus 5 volts DC. A motor 199 (analogous to motor 84 of FIG. 4B, motor 234 of FIG. 5A, and motor 142 of FIG. 8) is supplied with plus 6 volts DC from terminal 196 . Power supply 166 comprises a step-up transformer for converting the nominal 6 volts AC to 7.5 volts AC. The 7.5 volts AC is then rectified in a full Wave bridge to produce 9.7 volts of unregulated DC current. Three-terminal regulators provide the regulated outputs at terminals 192 , 194 , and 196 which are heavily filtered and protected by reverse EMF circuitry. Modem 171 is the major power consumer in electronics module 165 , typically using 350+ milliamps at plus/minus 5 volts DC when transmitting.
Modem 171 is typically a wideband digital modem having an IC/SS power line carrier chip set such as models EG ICS 1001, ICS 1002 and ICS 1003 manufactured by National Semiconductor. Modem 171 is capable of 300-3200 baud data rates at carrier frequencies ranging from 14 kHz to 76 kHz. U.S. Pat. No. 5,488,593 describes the chip set in more detail and is incorporated herein by reference. Any modem with an adequate data rate may be substituted for this choice of specific components.
PIC 170 controls the operation of a suitable valve control motor 199 through, for example, stepper motor controller 200 such as model SA1042 manufactured by Motorola. Controller 200 needs only directional information and simple clock pulses from PIC 170 to drive stepper motor 199 . An initial setting of controller 200 conditions all elements for initial operation in known states. Stepper motor 199 , preferably a MicroMo gear head, positions a rotating stem control valve 201 (analogous to needle valve heads 86 , 108 , and 144 of FIGS. 4B, 6 , and 8 , respectively), which is the principal operative component of the controllable gas-lift valve. Alternatively, motor 199 could position a cage analogous to cage 240 of FIG. 5 A. Motor 199 provides 0.4 inch-ounce of torque and rotates at up to 500 steps per second. A complete revolution of stepper motor 199 consists of 24 individual steps. The output of stepper motor 199 is directly coupled to a 989:1 gear head, and the output shaft from the gearhead may thus rotate at a maximum of 1.26 revolutions per minute, and can exert a maximum torque of 24.7 inch-pounds. This produces the necessary torque to open and close needle valve 201 . The continuous rotational torque required to open and close needle valve 201 is 3 inch-pounds with 15 inch-pounds required to seat and unseat the valve 201 .
PIC 170 communicates through modem 171 to the surface modem 122 via casing 24 and tubing string 26 . PIC 170 uses a MODBUS 584/985 PLC communications protocol, with commands and data ASCII encoded for transmission.
As noted previously with reference to FIG. 2, the embodiments thus far described for providing power and communications for controllable gas lift valve 52 are restricted to the well condition where annular space between tubing 26 and casing 24 is cleared of conductive fluid. In some circumstances for example during the unloading or kickoff processes, it may desirable to allow all of the valves in a gas lift well to be powered and controlled from the surface.
FIG. 12 illustrates an embodiment in which power and communications may be established for valves when the annulus 31 is only partially cleared of conductive fluid. As in the previous embodiments, surface equipment 44 includes an AC power source and communications device coupled by conductors 46 to tubing 26 and casing 24 . An upper choke 40 impedes AC which would otherwise be electrically short-circuited through hanger 22 , and the AC is thus directed down tubing string 26 to downhole equipment. At each location where it is desired to place a downhole electronics module 50 there is a choke 41 which creates an impedance to AC and therefore generates a voltage on the tubing 34 between the tubing above and below the choke. This voltage is connected by wires 64 and 66 to each electronics module 50 , and thus the voltage developed by the action of each choke 41 may be used to transfer power and communications signals to its corresponding electronics module 50 . Connections 64 , 66 , and the action of chokes 41 , also allow communications signals from each module 50 to be impressed on tubing 34 and received at surface equipment 44 . When the level of conducting fluid 182 is at level 1 of FIG. 12, none of the chokes will function to power their modules, since AC between tubing and casing is electrically short-circuited by fluid 182 before it reaches any of the chokes. However, when the fluid level is at level 2 , the upper choke 41 is effective since there is no longer an electrical short-circuit between tubing and casing above the upper choke 41 , and a potential difference can be developed on the tubing section that passes through the upper choke. Thus power and communications become available for the electronics module above level 2 . The same principle applies to the intermediate levels: as the surface of fluid 182 is driven downwards past levels 3 , 4 and 5 , the corresponding electronics modules at these levels become operable. The lowermost module is energized by choke 42 , and becomes operable when the fluid 182 is as illustrated in FIG. 12, below the lowest choke 42 .
Operation
FIG. 13 demonstrates the benefit of the availability of data and a method to respond to observations with a downhole control action. The chart of FIG. 13 presents a time series trend of three values. The first value is valve position 401 , expressed as a percent of full open (full open=100%) which is quantified by referencing the Y-axis on the right side of the plot. The second value is annulus pressure 402 , which is quantified by referencing the Y-axis scale on the left side of the plot. The annulus pressure is the pressure of the lift gas being supplied to the well and is upstream of the downhole controllable gas lift valve. The third value is the tubing pressure 403 , which is quantified by referencing the Y-axis on the left side of the plot. The tubing pressure is the pressure in the production tubing downstream of the controllable gas lift valve.
In a typical oil well, reducing the pressure in the tubing by injecting bubbles of gas into the liquid column above the point of lift gas injection into the tubing results in a decreased back-pressure on the reservoir. The decrease in back-pressure results in increased differential pressure from the reservoir to the tubing and therefore flow from the reservoir to the tubing and to the surface. An increase in downhole tubing pressure creates an increased back pressure on the reservoir, which decreases flow, even to the point of stopping inflow from the reservoir completely. It is important that the tubing pressure remain low and stable in order to achieve stable production rates from the reservoir to the surface and to the production facilities. Unstable flow causes upset conditions in production facilities due to the large changes in flow rate over short periods of time. Large surges in liquid and gas production can upset production processes creating inefficient and possibly hazardous conditions.
As previously discussed, conventional gas lift valves are configured before installation using information available at the time of configuration. As the well conditions change over time, the original configuration of the gas lift valve may no longer be appropriate for the new conditions. The effect of this miss-match is shown in FIG. 13 .
A gas lift valve port that is inappropriately large has been created by fully opening the downhole controllable gas lift valve as shown at 404 . The reservoir fluids are allowed to fill the tubing, causing the pressure to increase at 405 . Gas is introduced into the annulus, causing the annulus pressure to increase at 406 . The gas does not flow from the annulus to the tubing as the annulus pressure is less than the tubing pressure. The downstream pressure must be less than the upstream pressure in order to initiate flow. Gas does not flow from the tubing back into the annulus due to the presence of a reverse-flow check valve which prevents such backflow.
When the annulus pressure 406 increases sufficiently to exceed the tubing pressure 405 , gas flow is initiated into the tubing, the tubing pressure is reduced as the gas reduces the density of the tubing fluids via injection of bubbles into the liquid column at 407 . As the tubing pressure drops, the annulus pressure also begins to decline at 408 as the gas is flowing from the annulus to the tubing at a rate higher than gas is being introduced into the annulus from the surface. The gas flow rate from the annulus to the tubing is a function of the downhole controllable gas lift valve opening position which is 100%, and the differential pressure between the annulus and the tubing. If the gas flow out of the annulus into the tubing exceeds the injection rate into the annulus at the surface, the annulus pressure falls. If the gas flow out of the annulus into the tubing is less than the injection rate into the annulus at the surface, the annulus pressure increases.
If annulus outflow exceeds inflow for an extended period of time, the pressure difference between the annulus and the tubing may decline to level where insufficient gas enters the tubing to keep the fluids aerated to the degree required to maintain a low tubing pressure as shown at 409 . At that point, the tubing pressure begins to increase, 410 , as the density increases. The annulus pressure increases, 411 , also as the differential pressure between the annulus and tubing is so small that the gas flow rate into the tubing from the annulus is less than the rate of gas input into the annulus at the surface.
At some point, 412 , the pressure differential between the annulus and the tubing increases sufficiently for the volume of gas entering the tubing to reduce the density and cause the pressure to decrease, 413 . This begins another “heading” cycle that originally began at 407 . Left unchecked, such cycles repeat continuously. The surges of liquids and gas delivered to the producing facilities and the surges of lift gas demanded from the supply system generally influence not only the well suffering from the cause, but also affect other wells in the system. It is therefore desirable to correct this problem as quickly as possible. Conventional gas lift installations require that the well be closed in (stopping production) and remedial service work be performed on the well to remove the improperly sized or eroded valve and replace with one that has been configured for the new producing conditions. This results in significant cost and deferment of oil production.
In the case of a downhole controllable gas lift valve, the flow capacity of the valve can be adjusted without any service work or loss of production by closing the valve to some degree, such as closing from 97% open to 52% open as shown at 414 . The result of this action is to present excessive flow out of the annulus into the tubing, which causes the upstream (annulus) pressure to stabilize, 415 , and also the downstream (tubing pressure) to stabilize, 416 .
With downhole data available in real-time, a further adjustment, 417 , of the downhole controllable gas lift valve maintains stable annulus pressure, 418 , and tubing pressure, 419 , but causes the tubing pressure to decline slightly from the previous pressure. This pressure decline slightly reduces the back pressure on the reservoir, slightly increasing production rate as a result. A conventional gas lift system cannot provide the data or the ability to make such small adjustments, which enable continuous optimization of the producing system via feedback and response loops.
To illustrate the benefit of independent control for every lift gas valve in a well, FIG. 12 may be used to describe a process for unloading a gas lift well based on the methods of the present invention.
Typically the unloading process starts with the annulus 31 filled with completion fluid 182 , to level 1 of the well as illustrated in FIG. 12 . The completion fluid 182 is normally a brine which is electrically conductive, and thus creates an electrical connection between tubing 34 and casing 24 . Each downhole module 50 controls a motorized gas lift valve which may be opened to permit fluid, either liquid or gas, to pass from the annulus 31 to the interior of tubing 34 . At the start of the unloading process all of these lift gas valves are open, but none of the modules 50 can be powered since the completion fluid creates an electrical short circuit between the tubing 26 and the casing 24 at a point above all of the chokes 41 , 42 .
To initiate the unloading process, lift gas under pressure from a surface supply is admitted to the annulus 31 , and starts to displace the completion fluid through the open lift gas valves of each of the downhole modules 40 , thus driving down the level of the completion fluid. When the level of the completion fluid has reached level 2 indicated on FIG. 12, the first module 50 immediately above level 2 becomes powered and thus controllable, since the tubing and casing above level 2 are no longer electrically short-circuited above level 2 . The lift gas valve associated with the module immediately above level 2 may now be regulated to control the flow of lift gas into the tubing 34 . The rising column of lift gas bubbles lightens the liquid column between this first valve and the surface, inducing upwards flow in the production tubing. At this point in the unloading process therefore, the uppermost lift gas valve is passing gas under control from commands sent from surface equipment 44 , and the other lift gas valves are open to pass completion fluid but cannot yet be controlled.
Completion fluid continues to be expelled through the lower open valves until the completion fluid level reaches level 3 . The module 50 immediately above level 3 becomes powered and controllable as described with reference to the valve at level 2 , so that lift gas flow through the valve at level 3 may now be regulated by commands sent from the surface. Once this flow is established, the lift gas valve at level 2 may be closed, and lift of fluids in the tubing 34 is thus transferred from level 2 to level 3 .
In like manner, as the completion fluid continues to be expelled and its surface passes levels 4 and 5 , the gas lift valves at these levels become powered and controllable at progressively greater depths. As gas lift progresses down the tubing, the valves above are closed to conserve lift gas, which is directed to only the lowermost lifting valve. At the end of the unloading process, only the gas lift valve at choke 32 is open, and all valves above it are closed.
This method for controlling the unloading process ensures that each valve is closed at the correct moment. In existing practice and without benefit of means to control directly the lift gas valves, the cycling of the intermediate valves between open and closed is implemented by using pre-set opening and closing pressures. These preset values are chosen using design calculations which are based on incomplete or uncertain data. The consequence is that in existing practice the valves frequently open and close at inappropriate times, causing lift instability, excessive wear or total destruction of the valves, and also inefficiencies in lift gas usage from the need to specify the valve presets with pressure margins which reduce the range of gas pressures which can be made available for lift during the unloading and production processes.
A large percentage of the artificially lifted oil production today uses gas-lift to help bring the reservoir oil to the surface. In such gas-lift wells, compressed gas is injected downhole outside the tubing, usually in the annulus between the casing and the tubing and mechanical gas-lift valves permit communication of the gas into the tubing section and the rise of the fluid column within the tubing to the surface. Such mechanical gas-lift valves are typically mechanical bellows-type devices (see FIG. 1) that open and close when the fluid pressure exceeds the pre-charge in the bellows section. Unfortunately, a leak in the bellows is common and renders the bellows-type valve largely inoperative once the bellows pressure departs from its pre-charge setting unless the bellows fails completely, i.e. rupture, in which case the valve fails closed and is totally inoperative. Further, a common source of failure in such bellows-type valve is the erosion and deterioration of the ball valve against the seat as the ball and seat contact frequently during normal operation in the often briney, high temperature, and high pressure conditions around the ball valve. Such leaks and failures are not readily detectable at the surface and probably reduce a well's production efficiency on the order of 15 percent through lower production rates and higher demands on the field lift gas compression systems.
The controllable gas-lift well of the present invention has a number of data monitoring pods and controllable gas-lift valves on the tubing string, the number and type of each pod and controllable valves depends on the requirements of the individual well. Each of the individual data monitoring pods and controllable valves is individually addressable via wireless spread spectrum communication through the tubing and casing. That is, a master spread spectrum modem at the surface and an associated controller communicates to a number of slave modems. The data monitoring pods report such measurements as downhole tubing pressures, downhole casing pressures, downhole tubing and casing temperatures, lift gas flow rates, gas valve position, and acoustic data (see FIG. 6, sensors 112 , 114 , 116 , and 118 ). Such data is similarly communicated to the surface through a slave spread spectrum modem communicating through the tubing and casing.
The surface computer (either local or centrally located) continuously combines and analyzes the downhole data as well as surface data, to compute a real-time tubing pressure profile. An optimal gas-lift flow rate for each controllable gas-lift valve is computed from this data. Preferably, pressure measurements are taken at locations uninfluenced by gas-lift injection turbulence. Acoustic sensors (sounds less than approximately 20 kilohertz) listen for tubing bubble patterns. Data is sent via the slave modem directly to the surface controller. Alternatively, data can be sent to a mid-hole data monitoring pod and relayed to the surface computer.
In addition to controlling the flow rate of the well, production may be controlled to produce an optimum fluid flow state. Unwanted conditions such as “heading” and “slug flow” can be avoided. As previously mentioned, it is possible to attain and maintain the most desirable flow regime. By being able to determine such unwanted bubble flow conditions quickly downhole, production can be controlled to avoid such unwanted conditions. A fast detection of flow conditions allows the correction of any flow problems by adjusting such factors as the position of the controllable gas-lift valve, the gas injection rate, back pressure on tubing at the wellhead, and even injection of surfactant.
Even though many of the examples discussed herein are applications of the present invention in petroleum wells, the present invention also can be applied to other types of wells, including but not limited to water wells and natural gas wells.
One skilled in the art will see that the present invention can be applied in many areas where there is a need to provide a controllable valve within a borehole, well, or any other area that is difficult to access. Also, one skilled in the art will see that the present invention can be applied in many areas where there is an already existing conductive piping structure and a need to route power and communications to a controllable valve in a same or similar path as the piping structure. A water sprinkler system or network in a building for extinguishing fires is an example of a piping structure that may be already existing and may have a same or similar path as that desired for routing power and communications to a controllable valve. In such case another piping structure or another portion of the same piping structure may be used as the electrical return. The steel structure of a building may also be used as a piping structure and/or electrical return for transmitting power and communications to a valve in accordance with the present invention. The steel rebar in a concrete dam or a street may be used as a piping structure and/or electrical return for transmitting power and communications to a controllable valve in accordance with the present invention. The transmission lines and network of piping between wells or across large stretches of land may be used as a piping structure and/or electrical return for transmitting power and communications to a controllable valve in accordance with the present invention. Surface refinery production pipe networks may be used as a piping structure and/or electrical return for transmitting power and communications to a controllable valve in accordance with the present invention. Thus, there are numerous applications of the present invention in many different areas or fields of use.
It should be apparent from the foregoing that an invention having significant advantages has been provided. While the invention is shown in only a few of its forms, it is not just limited but is susceptible to various changes and modifications without departing from the spirit thereof.
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A gas-lift well having a controllable gas-lift valve is provided. The well uses the tubing and casing to communicate with and power the controllable valve from the surface. Induction chokes at the surface and downhole electrically isolate the tubing from the casing. A high band-width, adaptable communication system is used to communicate between the controllable valve and the surface. Additional sensors, such as pressure, temperature, and acoustic sensors, may be provided downhole to more accurately assess downhole conditions. The controllable valve is varied opened or closed, depending on downhole conditions, oil production, gas usage and availability, to optimize production and assist in unloading. While conventional, bellows-type, gas-lift valves frequently fail and leak—often undetected—the controllable valve hereof permits known precise operation and concomitant control of the gas-lift well.
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TECHNICAL FIELD
This invention relates to internal combustion engines and the manner of translating reciprocal motion into rotary motion with improved efficiency. More specifically, this invention is directed to an improved crankpin that provides a substantially constant total torque at all crankpin displacements so as to produce a substantially constant engine output.
BACKGROUND OF THE INVENTION
Internal combustion engine design has been subject to constant modifications and redesigns since its inception with the specific purpose of improving engine operating efficiency. Many improvements, however, that are directed toward improving engine efficiency are often not practical or are so costly that no real savings can be appreciated.
One particular line of internal combustion engine modifications for increasing engine output efficiency involves the alteration of the traditional four-stroke cycle. A typical four-stroke engine cycle is defined as including an intake stroke, a compression stroke, a power stroke, and an exhaust stroke. For its operation, at least one reciprocating piston is moved within a cylinder bore from a top dead center position (hereinafter abbreviated TDC) to a bottom dead center position (hereinafter abbreviated BDC), with four strokes occurring over two revolutions of the engine output shaft. Typically, in a first revolution, the piston will move inwardly from the TDC to BDC positions, defining the intake stroke during which an intake valve is opened so that an air/fuel mixture is suctioned into the engine cylinder above the piston. Thereafter, a compression stroke takes place as the piston moves outwardly so as to reduce the volume of the air/fuel mixture and increase the pressure within the engine cylinder prior to combustion of the explosive mixture. Normally, just before the beginning of the second revolution, the air fuel mixture is ignited at a point near the TDC position after which the power expansion stroke results causing the inward travel of the piston. Thereafter, the exhaust stroke occurs while the piston moves outwardly, as a result of which the exhaust gases are pumped through an exhaust valve that is opened in synchronization to the engine output shaft.
A conventional internal combustion engine includes a connecting rod pivotally connected via a wrist pin at one end to the piston and at another end to an offset portion of the output shaft for translating the reciprocal piston motion to the output shaft. The offset portion is spaced from the axis of rotation of the output shaft. The degree of offset defines the amount of leverage or the magnitude of the force moment acting on the output shaft since the leverage or moment is a function of the applied force as well as the distance between the applied force and the axis of rotation. During the power expansion stroke of the four-stroke cycle, chemical energy from the combustion of the air/fuel mixture is converted to linear motion of the piston caused by the expansion of the combusted gases. This energy is utilized to turn the engine output shaft and is released within each cylinder once during each two revolutions of the engine output shaft. Thus, it can be seen that the provision of multiple engine cylinders increases the number of times that an engine output shaft is powerfully driven during each revolution.
This conversion of chemical energy to transitional work of the piston is of course another area in which gains in efficiency have been advanced. Moreover, in modern engines, advances have also been made regarding the preparation of the air/fuel mixture by way of improved carburetors, fuel injection systems, and super-chargers.
However, even in light of the recent developments regarding fuel conversion to energy and fuel consumption efficiency, modern engines still run inefficiently with regard to the ability of the engine to actually convert the energy released by combustion into actual work output from the engine. To improve this, it is necessary to improve the manner in which the potential work available from the reciprocating piston is translated to the engine output shaft or output shaft.
When considering the forces that coact within the engine cylinder between the piston and the output shaft during the power expansion stroke, it will be appreciated that the pressure/force magnitude constantly decreases. The leverage arm, defined as the distance between the point of connection of the connecting rod to the output shaft and the axis of rotation of the output shaft, increases as the piston moves from the TDC position to a position approximately 90 degrees after TDC, after which it decreases. Neither the force applied to the piston from combustion nor the leverage arm decrease or increase linearly.
Since work is dependent on the product of distance times the force applied thereto, the reciprocating movement of the piston as driven during the power stroke becomes the potential work that is available to drive the output shaft. Thus, the ability and goal of an engine to most efficiently make use of the chemical energy provided from combustion is to find a way to more efficiently transfer the potential work from the reciprocating piston to the rotating output shaft.
There are many known methods and work paths to permit the piston to travel from TDC to BDC and transfer a portion of its available potential work to a rotary member or shaft. These include a conventional output shaft, a camdisk, a camdrum, and a gear chain. The common failure in each of these approaches is their inability to provide a consistent force magnitude to the rotating output shaft throughout the entire rotational arc through which an individual piston stroke acts. Rather, what these known engines have done is to deliver an erratic and inconsistent force to the rotating output shaft while applying some random magnitude of force during the rotational arc throughout which each individual piston acts. An example is shown in U.S. Pat. No. 2,006,498 to Dassett, that utilizes a noncircular cam-type output shaft for transferring the work from the piston. Although this patent does inherently provide a cam profile that modifies the leverage arm acting on the output shaft, it does not attempt to provide a consistent force magnitude to the engine output shaft throughout the entire rotational are through which an individual piston stroke acts. More specifically, the device includes a cam profile which, at the start of the downward stroke of the piston during expansion, produces a rapid displacement of the piston to thereby permit a quick expansion stroke for greater mechanical efficiency and less heat production. However, because the patent does not realize that it is important to provide a consistent torque throughout the power stroke, the Dassett device falls far short of the extent to which the leverage ann can be modified.
Other types of prior art devices that modify the piston strokes of a four cycle internal combustion engine are disclosed in U.S. Pat. No. 4,467,756 to McWhorter and U.S. Pat. No. 4,466,403 to Menton. These devices include a means to modify the crank offset or leverage arm during the course of engine operation. Specifically, the crank arm is effectively lengthened before the power expansion stroke for providing an increased leverage to produce greater torque by increasing the mechanical advantage during the power stroke. Although these devices increase engine output torque and may improve engine efficiency to at least some degree, they do not modify the crank offset during the power stroke nor do they attempt to provide a consistent force magnitude.
Many other types of cam-driven output shaft internal combustion engines are known in the prior art including those with specifically designed cam paths that are altered to provide variable stroke mechanisms. That is to say, certain of the strokes of the typical four-cycle are modified to change the length of stroke and/or timing. An example is shown in U.S. Pat. No. 1,728,363 to Rightenour, which discloses a double cam device for providing two reciprocating piston motions during a single output shaft rotation, wherein the cam profiles are modified specifically for varying piston speed during certain stroke instances and defining different stroke lengths depending on the stroke. Moreover, Rightenour recognizes that using a rapid movement cam profile during the firing stroke provides a modified leverage at a specific point. Again, however, the cam path is not tailored for maximizing engine operating efficiency in the translation of reciprocal motion to rotary motion.
The devices disclosed in the following U.S. Pat. No. 3,895,614 to Bailey, U.S. Pat. No. 3,687,117 to Panariti, U.S. Pat. No. 1,209,708 to Houlehan, U.S. Pat. No. 879,289 to Mayo et al., U.S. Pat. No. 1,748,443 to Dawson, and U.S. Pat. No. 2,528,386 to Napper are of interest for their disclosure of engine output cam shafts which include guide tracks defined on a disc-like member associated with the output shaft and where the piston includes a roller or pin-type mechanism that is guided within the guide tracks. The guide tracks are used to translate the reciprocating motion of the piston into rotary motion of the output shaft. These patents disclose various guide paths for translating the reciprocating to rotary motion; however, they do not attempt to increase the output efficiency by providing a consistent torque magnitude to the output shaft.
U.S. Pat. No. 5,060,603 to Williams discloses a device for increasing an internal combustion engine's output efficiency by improving the efficiency of energy conversion from a reciprocating piston motion to rotary output shaft motion. Specifically, it accomplishes this by providing at last one disc-like element rotatably fixed to the engine output shaft, the disc-like element having a work receiving guide groove defined therein which engages with a lower end of a connecting rod pivotally extending from the reciprocating piston. The work receiving guide groove increases the length of the leverage arm while the pressure force acting on the reciprocating piston decreases to provide a substantially constant torque during the expansion stroke. However, the work receiving guide groove is designed by taking into account only a single cylinder and ignoring the contributions and parasitic effects of the other cylinders. As a result, because it does not account for the erratic demands of the parasitic cylinders, the work receiving guide groove provides an erratic torque output rather than the desired uniform torque output.
It is clear from the above that many attempts have been made to improve engine operating efficiency with respect to the manner of translation of reciprocating motion of a piston to the rotary motion of a crank or cam-type output shaft including the use of additional leverage providing mechanisms or cam profiles affecting piston speed. However, none of these prior art references have contemplated that it is necessary to provide a consistent total force magnitude from all cylinders, including the parasitic effects of cylinders which are not in their power stroke, to the engine output shaft.
SUMMARY OF THE INVENTION
It is thus a primary object of the present invention to overcome the above noted inefficiencies, shortcomings and deficiencies of the prior art mechanisms.
It is a further object of the present invention to provide an engine output shaft design that provides a consistent force magnitude to a rotatable engine output shaft by controlling the point of application of the force from the reciprocating piston to the output shaft.
It is another objective of the present invention to provide a means for regulating and metering the torque magnitude imparted to the output shaft to approximately the same net torque level for all rotational increments.
It is another object of the present invention to provide a mechanism for translating reciprocating motion to rotary motion on a cyclic basis in combination with an internal combustion engine, wherein the internal combustion engine includes at least one reciprocating piston slidably provided within a cylinder, a control means for synchronously supplying a combustible gas mixture to the cylinder and igniting the mixture to drive the piston inwardly during the power expansion stroke of the piston cycle, and a rotatably mounted engine output shaft which is operatively connected to the reciprocating piston by a connecting means that translates the reciprocal motion to rotary motion. The engine output shaft includes a work receiving element that changes the position of connection of the connecting means between the engine output shaft and the piston for each cylinder so as, consistent with the contributions and demands of the other cylinders, to increase or decrease the distance between the axis of rotation and the connection to the engine output shaft as the piston force decreases or increases.
It is yet another object of the present invention to provide a substantially uniform net torque output of the engine output shaft throughout the engine cycle by providing a crankpin assembly that continually changes the effective moment arm.
It is still yet another object to provide an engine output shaft with an element having a torque guide path designed in accordance with the present invention to provide a substantially uniform work output from the engine output shaft even though the engine output shaft is driven by intermittent pulses of energy from the reciprocating pistons and the piston itself is provided with a force/pressure that decreases in magnitude during the power expansion stroke.
It is yet another object of the present invention to provide a method for making an engine output shaft for use in an internal combustion engine in combination with a reciprocating piston so as to convert reciprocating motion into rotary motion while providing a substantially constant torque output.
It is still another object to provide a method for making an engine output shaft for use in an internal combustion engine including the step of designing a crankpin means fixed to rotate with the engine output shaft for determining the point of application of the force from the reciprocating piston to the engine output shaft and controlling the degree of angular rotation of the engine output shaft during the increments of the power stroke. This is achieved by determining for a crankpin assembly having at least two fixed crankpin offsets, those offset values which result in total torque on the crankshaft for uniform increments of crankshaft rotational displacement most nearly approximating a predetermined mean torque value for all increments.
The above noted objects of the present invention and others not specifically referred to, but readily apparent to those skilled in the art, may be accomplished by providing an internal combustion engine including at least one piston reciprocally mounted within an internal combustion engine cylinder, a synchronous control means which supplies and controls the ignition of combustible gas to the cylinder for causing the power expansion stroke of the piston cycle, and an engine output shaft rotatably mounted within the internal combustion engine having means for converting reciprocating piston motion to rotary output shaft motion while providing a substantially constant torque output from the engine output shaft. More specifically, the engine output shaft includes a variable offset crankpin/connecting rod connection for achieving a relatively consistent torque magnitude throughout rotation of the crankshaft. The variable offset connection varies the crankpin offset during the rotation of the crankshaft, thus varying the moment arm in a predetermined manner to closely produce a predetermined ideal torque during each increment of rotational movement of the crankshaft.
In another aspect of the invention, the variable offset connection includes a connecting rod connected at one end to an engine piston and mounted via a cylindrical bearing surface for slidable movement at an opposite end to a crankpin assembly which is connected to the engine crankshaft. The crankpin assembly includes a crankpin, first and second transition rockers positioned on opposite sides of the crankpin in complementary shaped concavities to permit the rockers to pivot relative to the crankpin during rotation of the crankshaft. The rockers have inner semi-cylindrical surfaces having centers of curvature defining transition offset apexes. An outer surface of each rocker and first and second opposite bearing surfaces of the crankpin all have radii of curvature equal to the radius of curvature of the cylindrical connecting rod bearing surface to permit unobstructed, smooth sliding movement between connecting rod bearing surface and the crankpin and rocker surfaces as the crankshaft rotates. The crankpin has two fixed crankpin offset apexes, defined as CPOA MIN and CPOA MAX , and defined by the distance between the longitudinal axis of the crankshaft and, respectively, the origin of the radius of curvature for each crankpin bearing surface. During rotation of the crankshaft, the crankpin offset apex will shift from CPOA MIN through TOA1 to CPOA MAX through TOA2 and back to CPOA MIN as the crankshaft moves through 360°. Thus, the moment arm is varied in a predetermined manner to more closely achieve a predetermined ideal torque during rotation of the crankshaft.
In still another aspect of the invention, the variable offset connection includes a modified crankpin assembly which includes a rotator bearing sleeve having an aperture formed therein for receiving a crankpin. The rotator bearing sleeve includes an uninterrupted, continuous outer bearing surface for sliding movement relative to cylindrical connecting rod bearing surface. The bearing sleeve further includes a rotator integral with the sleeve for slidably engaging a complementary shaped pivot surface on one side of the crankpin. On the other side of the crankpin, a transition roller assembly effectively permits the transition between the crankpin offsets without use of a rotator in the same plane as the integral rotator. This is accomplished by a transition roller pivotally mounted on a transverse support, the transition roller including a concavity shaped to receive a guide pin extending from the connecting rod into the guide groove at the beginning of the transition from the maximum crankpin offset to the minimum crankpin offset. As the crankshaft rotates, the transition roller engaging the guide pin also rotates to permit the guide pin to continue its movement through the guide groove. In this manner, as with the first embodiment of this invention, the moment arm can be optimally varied resulting in the desired substantially constant output torque without the practical problem of transitioning between the multiple bearing surfaces of the first embodiment.
In still another aspect of the present invention the shape and dimensions of the crankpin assembly can be determined by determining the crankpin and transition offset apexes which produce a variable offset and corresponding desired moment arms at specific displacement increments throughout rotation to create a substantially constant torque output. This is accomplished by an iterative calculation which involves determining an ideal mean torque as a target value for each displacement increment, selecting first estimated values of minimum and maximum crankpin offsets and transitional crankpin offsets, calculating the moment arms for each increment using the selected offsets, calculating the crankshaft torque for a single cylinder during at least its power and compression strokes at each increment using the calculated moment arm values, determining the torque contribution and/or parasitic effect on torque for each cylinder of the engine at each increment and summing to generate the total torque for each increment. The total torque values at each increment can then be individually compared to the ideal mean torque value and, based upon the observed deviations from the target torque value, adjustments can be made to the initially selected offset values and the calculation repeated until the selected offsets best reproduce the target mean torque value.
For a more complete understanding of the invention, reference is made to the following detailed description taken in conjunction with the accompanying drawings for which a preferred embodiment is described.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is an end view of the variable offset crankshaft/connecting rod connection of the present invention with the connecting rod in its outermost position with the engine piston at top dead center.
FIG. 1B is a partial sectional view of the variable offset crankshaft/connecting rod connection of the present invention taken along line 1B--1B in FIG. 1A.
FIG. 1C is a schematic view of the crankpin assembly of the present invention showing the various variable offsets.
FIGS. 1D-1J are sequential end views of the variable offset crankshaft/connecting rod connection of the present invention at various rotational displacement increments during one rotation of the crankshaft.
FIG. 2 graphically illustrates the torque output of the engine crankshaft during 120° of displacement for a conventional engine having a single fixed offset crankpin.
FIG. 3 graphically illustrates the torque output of the engine crankshaft during 120° of displacement for an engine having a variable offset crankpin in accordance with the present invention.
FIG. 4 graphically compares the torque output of the engine crankshaft due to cylinder pressure only with the torque output due to both cylinder pressure and inertial effects during 120° of displacement for an engine having a variable offset crankpin in accordance with the present invention.
FIG. 5 graphically compares the torque output of the engine crankshaft due to cylinder pressure only with the torque output due to both cylinder pressure and inertial effects during 120° of displacement for an engine having a variable offset crankpin and a modified bore to stroke ratio in accordance with the present invention.
FIG. 6A is an end view of a second embodiment of the variable offset crankshaft/connecting rod connection of the present invention with the connecting rod in its outermost position with the engine piston at top dead center.
FIG. 6B is a partial sectional view of the variable offset crankshaft/connecting rod connection of the second embodiment of the present invention taken along line 6B--6B in FIG. 6G.
FIGS. 6C-6H are sequential end views of the variable offset crankshaft/connecting rod connection of the second embodiment of the present invention at various rotational displacement increments during one rotation of the crankshaft.
FIG. 6I is a schematic view of the crankpin assembly of the second embodiment of the present invention showing the various variable offsets.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the figures, wherein like reference numerals designate like or corresponding parts throughout the figures, and in particular to FIGS. 1A-1J, there is shown one embodiment of the variable offset crankshaft/connecting rod connection of the present invention for achieving a relatively consistent torque magnitude throughout rotation of the crankshaft. The variable offset connection, indicated generally at 100, varies the crankpin offset during the rotation of the crankshaft, thus varying the moment arm in a predetermined manner to closely produce a predetermined ideal torque during each increment of rotational movement of the crankshaft. Variable offset connection 100 includes a connecting rod 102 connected at one end to an engine piston (not shown) and mounted for pivotal movement at an opposite end on a crankpin assembly 104. Crankpin assembly 104 is connected to a crankshaft, indicated at 106, extending along a longitudinal axis 108.
As in all conventional reciprocating piston type engines, the piston (not shown) reciprocates through a power stroke, an exhaust stroke, an intake stroke and a compression stroke during two rotations of crankshaft 106 in a typical four-stroke engine. In a two-stroke engine, each rotation of crankshaft 106 would result in a compression stroke followed by a power stroke. In either engine, the pressure forces resulting from combustion are transmitted through the piston and connecting rod 102 to crankshaft 106 via crankpin assembly 104. The torque transmitted to crankshaft 106 is a product of the force acting on the piston transmitted through connecting rod 102 and the moment arm, that is, the perpendicular distance between longitudinal axis 108 and the force component acting along the centerline of the connecting rod. Variable offset connection 100 effectively varies the moment arm by varying the offset of the crankpin from the axis 108 during rotation of crankshaft 106 to achieve a more consistent torque magnitude throughout rotation of crankshaft 106.
Referring to FIGS. 1A and 1B, connecting rod 102 includes a crank end 109 including a first arcuate portion 110 having a semi-cylindrical bearing surface 112, and a second arcuate portion 114 also having a semi-cylindrical bearing surface 116. Second arcuate portion 114 is connected to first end portion 110 in a conventional manner so that first semi-cylindrical bearing surface 112 and second semi-cylindrical bearing surface 116 form a cylindrical connecting rod bearing surface 118 for abutment by crankpin assembly 104.
Crankpin assembly 104 includes a crankpin 120, a first transition rocker 122 positioned on one side of crankpin 120 and a second transition rocker 124 positioned on an opposite side of crankpin 120. First transition rocker 122 and second transition rocker 124 each include inner semi-cylindrical surfaces 123 and 125, respectively, having centers of curvature, hereinafter referred to as transition offset apexes 1 (TOA1) and 2 (TOA2), respectively, as shown in FIGS. 1A and 1C. Inner surface 123 is positioned in a complementary shaped first concavity 126 formed in the respective side of crankpin 120 to permit rocker 122 to pivot relative to crankpin 120 during rotation of crankshaft 106. Likewise, inner surface 125 of second transition rocker 124 is pivotally positioned in a second concavity 128 formed in the respective side of crankpin 120. An outer surface 130 of each transition rocker 122, 124 is formed with a radius of curvature equal to the radius of curvature of cylindrical connecting rod bearing surface 118. Likewise, crankpin 120 includes a first bearing surface 132 and a second bearing surface 134, positioned opposite first bearing surface 132, each having a radius of curvature equal to the radius of curvature of cylindrical connecting rod bearing surface 118. In this manner, crankpin 120 and first and second transition rockers 122, 124, respectively, are shaped to complementarily abut cylindrical bearing surface 118 to permit unobstructed, smooth sliding movement between connecting rod bearing surface 118 and surfaces 130, 132, 134.
As shown in FIG. 1B, crankshaft 106 includes a counterweight 136 extending transversely from one side of crankshaft 106 and a transverse support 138 integrally formed with counterweight 136 and extending from the opposite side of crankshaft 106. Crankpin 120 includes an axial end boss 140 for connection to crankshaft 106 via, for example, transverse support 138. Transverse support 138 includes a guide groove 135 formed in part by an annular guide wall 137 having an inner guide surface 139. Connecting rod 102 includes a guide pin 141 extending transversely from first portion 110 into guide groove 135. Inner surface 139 is shaped to form a minimal clearance with guide pin 141 throughout rotation to ensure the motion of connecting rod 102 as determined by crankpin offsets and transition offsets (described more fully hereinbelow). Also, guide wall 137 functions to pull the connecting rod downwardly during the intake stroke. Although gas pressure in the combustion chamber forces the respective piston and connecting rod downwardly during the power stroke, the cylinder pressure during the intake stroke is insufficient to move the piston in the absence of turbo- or super-charging. Guide wall 137 pulls on guide pin 141 during the intake stroke thereby ensuring that the connecting rod bearing surface 118 remains in abutment with crankpin bearing surface 132 and rotator surface 130 of transition rotator 122 during the appropriate portions of angular rotation corresponding to the intake stroke.
FIG. 1A illustrates connecting rod 102 in its outermost position with the engine piston at its top dead center (TDC) position, i.e. at the end of the compression stroke and the beginning of the power stroke. In this position, a minimum crankpin offset CPO MIN is indicated by the distance between the longitudinal axis 108 of crankshaft 106 and a minimum crankpin offset apex CPOA MIN , which is the origin of the radius of curvature for both crankpin bearing surface 132 and connecting rod bearing surface 118, as shown in FIG. 1C. During rotation of the crankshaft, the crankpin offset apex will shift between CPOA MIN and a maximum crankpin offset apex CPOA MAX which defines a maximum crankpin offset CPO MAX , corresponding to the distance between longitudinal axis 108 and CPOA MAX . Thus, the present invention varies the moment arm in a predetermined manner to more closely achieve a predetermined ideal torque during rotation of the crankshaft as discussed more fully hereinbelow.
Now, referring to FIG. 1D, the variable offset connection 100 is illustrated with the piston (not shown) at the 60° after top dead center (ATDC) position as the piston moves through its power stroke. During the stroke, the downward force of connecting rod 102 imparts a clockwise torque to crankshaft 106 via crankpin assembly 104. As crankpin assembly 104 moves in the clockwise direction, crankpin bearing surface 132 slides along connecting rod bearing surface 118. Also, outer surfaces 130 of first and second transition rockers 122, 124 slide along connecting rod bearing surface 118. As shown in FIG. 1D, at a predetermined angular position of rotation, i.e. 65° ATDC, when TOA1 moves into alignment with the connecting rod centerline, indicated at L, connecting rod 102 begins to pivot relative to crankpin assembly 104, marking the end of the rotational arc utilizing CPOA MIN , and the beginning of a rotational arc utilizing the linear distance between TOA1 and crankshaft axis 108 as the crankpin offset, hereinafter referred to as transition offset TO1. Thus, the circumferential position of TOA1 determines the timing of the beginning of the increasing transition period from CPO MIN to CPO MAX during which the crankpin offset increases from its minimum to its maximum value. TO1 remains the offset during the entire increasing transition period. Specifically, as crankpin 120 rotates in a clockwise direction around longitudinal axis 108, connecting rod 102 pivots in a counterclockwise direction away from longitudinal axis 108 so that connecting rod bearing surface 118 begins to pivot away from crankpin bearing surface 132 and toward crankpin bearing surface 134. As crankshaft 106 continues to rotate in a clockwise direction and crank end 109 of connecting rod 102 continues to slidably move away from longitudinal axis 108 (FIG. 1E), first transition rocker 122 pivots in first cavity 126 until bearing surface 118 abuts crankpin bearing surface 134 as shown in FIG. 1F. During this movement, outer surface 130 of first transition rocker 122 remains in continuous abutment with connecting rod bearing surface 118 with TOA1 in alignment with the connecting rod centerline L. Also, as connecting rod bearing surface 118 approaches crankpin bearing surface 134, outer surface 130 of second transition rocker 124 pivots into abutment with bearing surface 118 as shown in FIG. 1F. In this position, the crankpin offset apex has now shifted to CPOA MAX with CPO MAX being the crankpin offset. Thus, the effect of the movement of the connecting rod 102 from the position shown in FIG. 1D to the position shown in FIG. 1F is to shift the crankpin offset dimension from CPO MIN to TO1, which functions as the crankpin offset during the transition period, and then to CPO MAX when the connecting rod center C coincides with the CPOA MAX . The maximum offset CPO MAX is maintained as the piston moves to its bottom dead center (BDC) position as shown in FIG. 1G.
Therefore, it can be seen that the variable offset connection 100 of the present invention shifts the position of the offset apex of connecting rod 102 relative to crankshaft longitudinal axis 108 so as to vary the moment arm in an optimal manner during the power stroke. Referring now to FIG. 1H, as crankshaft 106 continues to rotate in the clockwise direction, the exhaust stroke begins and the associated piston begins to move outwardly. During this movement of the piston toward the TDC position, the connecting rod 102 slidably pivots relative to crankpin assembly 104 such that crankpin bearing surface 134, and outer surfaces 130 of first and second transition rockers 122 and 124, slidably move, in a clockwise direction, along connecting rod bearing surface 118. During this rotation, CPO MAX is maintained as shown in FIG. 1H with the piston at approximately 90° before top dead center (BTDC). At a predetermined angular position of rotation when TOA2 moves into alignment with the connecting rod centerline L, connecting rod 102 begins to pivot relative to crankpin assembly 104, marking the end of the rotational arc utilizing CPOA MAX and CPO MAX , and the beginning of a rotational arc utilizing the linear distance between TOA2 and crankshaft axis 108 as the crankpin offset (hereinafter referred to as transition offset TO2). Thus, the circumferential position of TOA2 determines the timing of the beginning of the decreasing transition period from CPO MAX to minimum CPO MIN . Continued rotation of crankshaft 106 in a clockwise direction causes connecting rod 102 to pivot in a clockwise direction as shown in FIG. 1I, toward longitudinal axis 108 so that connecting rod bearing surface 118 begins to move toward crankpin bearing surface 132 and away from crankpin bearing surface 134. As crankshaft 106 continues to rotate in a clockwise direction and crank end 109 of connecting rod 102 continues to pivot toward longitudinal axis 108, second transition rocker 124 pivots in second concavity 128 until crankpin bearing surface 134 abuts bearing surface 118 as shown in FIG. 1J. During this movement, outer surface 130 of second transition rocker 124 remains in continuous abutment with connecting rod bearing surface 118 with TOA2 in alignment with the connecting rod centerline L. Also, as connecting rod bearing surface 118 approaches crankpin bearing surface 132, outer surface 130 of first transition rocker 122 pivots into abutment with bearing surface 118 as shown in FIG. 1J. In this position, the crankpin offset apex has now shifted to CPOA MIN and the offset value to CPO MIN . Thus, the effect of the movement of the connecting rod 102 from the position shown in FIG. 1H to the position shown in FIG. 1J is to shift the offset from CPO MAX to TO2 and then from TO2 to CPO MIN so that the connecting rod center C coincides with CPOA MIN as illustrated by FIG. 1J. CPO MIN is maintained as the piston moves to its TDC position as shown in FIG. 1A. Thus, first and second transition rockers 122 and 124 effectively permit smooth transitional movement of connecting rod 102 relative to crankpin 120 during each transition between CPO MIN and CPO MAX over a range of angular rotation while effectively transmitting forces between connecting rod 102 and its crankpin 120. As a result, the moment arm can be optimally varied resulting in an output torque from the engine, during each increment of rotation, which more closely approximates an optimum constant torque.
The movements of the components of variable offset connection 100 during the intake stroke, which follows the exhaust stroke in a four stroke engine, are the same as described hereinabove with respect to the power stroke. Also, the compression stroke, which follows the intake stroke, is identical to the exhaust stroke as described hereinabove. The minimum and maximum crankpin offset apexes CPOA MIN and CPOA MAX , the corresponding offset dimensions CPO MIN and CPO MAX , the transition offset apexes TOA1 and TOA2, and the corresponding transition offsets TO1 and TO2, remain unchanged.
In accordance with the present invention the shape and dimensions of the crankpin assembly can be determined, i.e. the crankpin and transition offset apexes, which produces a variable offset and corresponding desired moment arms at specific displacement increments throughout rotation to create a more constant torque output relative to an ideal mean torque value. Specifically, the present method permits the determination of CPO MIN , CPO MAX , TO1, TO2 and thus the timing of the beginning, and duration, of the transition periods so as to optimally vary the moment arms throughout rotation.
The determination of the optimum crankpin offsets necessary to achieve optimum torque output requires the calculation of an ideal mean torque as a target value. The ideal mean torque for a given engine may be calculated by averaging the resultant torque values experienced by the crankshaft for a selected number of increments of cylinder volume displaced during the power stroke.
Referring to Table I, the crankshaft torque per square inch for a single cylinder at various displacement increments can be determined from known engine values for any given engine. For example, Table I sets forth the pressure and displacement, respectively, of an individual cylinder for an engine including a conventional crankpin/connecting rod connection having a fixed crankpin offset equal to one-half the stroke, e.g., 2 inches. Thus, columns A and B of Table I reflect an individual cylinder's pressure-volume diagram in a columnized format. The displacement increments correspond to every 10 degrees of crankshaft rotational displacement (column C). The moment arm, i.e. leveraging effect, of the connecting rod upon the crankshaft can be calculated for each displacement increment using the 2 inch offset and the well known geometry produced by a circular offset configuration (column D). Thereafter, the product of the moment arm for each increment and the corresponding cylinder pressure is the crankshaft torque magnitude per square inch of piston area for each increment (column E).
Table I is based on a power stroke of 0°-180°, and a compression stroke of 180°-360°, while omitting the intake and exhaust strokes which comprise another 360°. The intake and exhaust strokes make no torque contribution to the engine torque output and minimal torque demands. As a result, these strokes have been omitted to simplify the calculations and enhance the clarity of the present example, but could be taken into consideration if a more refined approach is desired, as explained more fully hereinbelow.
TABLE I__________________________________________________________________________INCREMENTAL TORQUE CALCULATION FOR SINGLE CYLINDERDISPLACEMENT C D EINCREMENT B CRANKSHAFT CRANKSHAFT CRANKSHAFT(CHANGE IN STROKE CYLINDER ROTATION MOMENT LB.-IN.FROM TOC) FORCE-P.S.I. DEGREES ARM-INCHES PER SQ. IN.__________________________________________________________________________0" 700 0 0 0 670 10 .44 683 600 20 .87 605 550 30 1.23 518 460 40 1.55 441 306 50 1.80 342 282 60 1.97 282 234 70 2.06 228 195 80 2.06 191 164 90 2.00 159 137 100 1.88 137 124 110 1.70 122 110 120 1.50 116 100 130 1.26 102 90 140 1.02 95 80 150 .77 90 70 160 .51 87 50 170 .26 404" 30 180 0 190 .26 200 .51 210 .77 220 1.02 230 1.26 240 1.50 250 1.70 4 260 1.88 -4 19 270 2.00 -17 35 280 2.06 -32 55 290 2.06 -52 68 300 1.97 -68 95 300 1.80 -95 120 320 1.55 -114 150 330 1.23 -141 165 340 .87 -167 175 350 .44 -1840" 360 0 -190__________________________________________________________________________
Referring now to Table II, the individual cylinder torque values of Table I may then be used to determine the total combined torque on the crankshaft during each displacement increment due to the gas pressure on each piston associated with each cylinder of the engine during the power stroke of cylinder 1. Assuming a 6 cylinder engine, Table II need only consider 120° of displacement of the crankshaft since each of the 6 cylinders begin a power stroke 120° after the previous one began its power stroke, to form a repeating 120° cycle. It will be appreciated by those skilled in the art that this 120° repeating cycle is standard for a 4 cycle 6 cylinder engine, as is a 90° repeating cycle standard for an 8 cylinder engine, and a 180° repeating cycle standard for a 4 cylinder engine.
TABLE II______________________________________CALCULATION OF IDEAL MEAN TORQUECRANKSHAFT TOTALROTATION CYLINDER NO./STROKE TORQUEDEGREES 1 2 3 4 5 6 VALUES______________________________________10 300 129 42920 526 97 -7 61630 637 69 -34 67240 684 44 -64 66450 629 11 -104 53660 555 0 -134 42170 470 -162 30880 393 -176 21790 318 -173 145100 258 -145 113110 207 -81 126120 174 174TOTAL 4421IDEAL 368MEAN TORQUE______________________________________
Table II displays, for engine cylinders 1 through 6, with cylinder 1 at 0° T.D.C. at the beginning of its power stroke, the torque magnitude values for each cylinder at the respective displacement points. As is evident, cylinder 5 is undergoing a compression stroke during this particular 20° cycle resulting in negative torque values. Cylinder 4 is in the last 60° of its power stroke while cylinders 2, 3 and 6 are in their exhaust and/or intake strokes. The torque values for all cylinders are totaled for each displacement, resulting in total torque values taking into account the contributions and parasitic effects of all engine cylinders for each displacement point. The total torque values are then summed and divided by the number of increments, i.e. 12, to calculate the ideal mean torque value, i.e. 368.
An alternative method of determining the ideal mean torque value available to each rotational increment may be achieved by, first, determining the mean pressure of an engine cylinder using, for example, a pressure-volume diagram and then determining the number of power strokes that occur during a single 180° revolution, i.e. one for a 4 cylinder, 1.5 for a 6 cylinder, 2 for an 8 cylinder, assuming a 4 cycle engine. The mean pressure, per square inch of cylinder area, available to all rotational displacement increments can then be calculated by multiplying the mean pressure by the number of power strokes. The mean moment arm of the crankshaft crankpin is calculated by dividing the displacement length, i.e. stroke, which in the present example is 4 inches, by 4, as dictated by the circular path traversed by the crankpin. Thereafter, multiplying the mean pressure per square inch of cylinder area by the mean moment arm yields the ideal torque magnitude available to each rotational increment, which for the 6 cylinder engine of the preceding example is 368.
The torque values from the "total"0 column of Table II are graphically illustrated in FIG. 2. As can be seen, the torque experienced by the crankshaft fluctuates dramatically throughout the rotation of the shaft. Also illustrated in FIG. 2 is the ideal mean torque value of 368. The unnecessarily large deviations of the actual torque from the ideal torque throughout the rotational displacement of the crankshaft creates undesirable inefficiencies in engine operation due to an inefficient work path for the mechanical transition of torque during the displacement. In addition, extreme torque fluctuations necessarily result in undesirable torsional vibrations in the engine drive train requiring various complex and expensive damping devices and resilient connections to other crankshaft driven components, in order to minimize component wear and damage. Also, the vibrations may be transferred to the engine timing gear train undesirably causing increased noise, premature engine wear and, thus, reduced gear and shaft life.
The variable offset crankshaft/connecting rod connection 100 of the present invention may be designed in accordance with the method of the present invention to produce an optimum torque output which more closely approximates the ideal torque value, thereby avoiding the inefficiencies and deleterious effects associated with excessive torque fluctuations. The inconsistent torque magnitudes for a single cylinder at each displacement increment of Table I is due to both the changing gas pressure in the cylinder and the varying moment arm dimension as shown in Table I. Although the gas pressure is not efficiently subject to control, the variable offset connection 100 of the present invention can be used to vary the moment arm during rotation in an optimal manner to achieve a more consistent torque magnitude at each increment. As is well known, the moment arm dimension is a by-product of the geometric relationship between the connecting rod force component applied along the centerline of the connecting rod and the centerline of the crankshaft at each displacement point. The connecting rod force component is, of course, determined by a geometric relationship between the centerline of the piston and the connecting rod. Thus, in order to create a more consistent torque magnitude at each displacement increment, it is necessary to vary the moment arm during rotation in such a manner that, when the moment arm is multiplied by the cylinder pressure at a corresponding displacement point and the contributions of all cylinders are summed, a torque magnitude is produced for the engine which approximates the ideal torque value. Specifically, with reference to Table II and FIG. 2, it can be seen that the total torque undesirably increases to an excessive level above ideal mean torque 368 during a first portion of the power stroke and then undesirably decreases to an excessively low level below 368 during the latter portion of the power stroke. Thus, decreasing the crankpin offset and, therefore, the moment arm during the first portion of the power stroke, and increasing the offset and moment arm during the latter portion would appear to be a first step toward limiting the peak deviations from the mean ideal torque.
Having determined an ideal mean torque magnitude of 368 for each displacement point in the above-described example, optimum moment arm dimensions for the crankpin assembly of the present invention at each of the displacement increments may now be calculated using an iterative process of selecting minimum and maximum crankpin offsets, CPO MIN and CPO MAX , and transition offsets, TO1 and TO2, and using these offsets to calculate the moment arm at each displacement increment until the total torque, caused by the effects of all cylinders at each increment approximates the ideal torque as closely as practically possible. The iterative process will be discussed with respect to Tables III and IV which, although similar to Tables I and II, are very different in the use of minimum and maximum crankpin offsets and transition offsets to determine the moment arms at each displacement increment. It will be appreciated, in lieu of the columnar calculation process of Tables III and IV, a computer algorithm, based on the same process, may be used to more effectively and quickly determine the minimum and maximum crankpin offsets and the transition offsets, and the corresponding apexes, which result in the optimum moment arm values.
TABLE III__________________________________________________________________________INCREMENTAL TORQUE CALCULATION FOR SINGLE CYLINDERDISPLACEMENT C D EINCREMENT B CRANKSHAFT CRANKSHAFT CRANKSHAFT(CHANGE IN STROKE CYLINDER ROTATION MOMENT LB.-IN.FROM TOC) FORCE-P.S.I. DEGREES ARM-INCHES PER SQ. IN.__________________________________________________________________________0 700 0 0 0 680 10 .24 163 650 20 .46 299 599 30 .67 401 539 40 .82 442 477 50 .96 458 421 60 1.06 446 350 70 1.32 462 291 80 1.71 498 236 90 2.02 477 194 100 2.30 446 155 110 2.35 364 134 120 1.67 224 120 130 1.50 180 105 140 1.31 138 98 150 1.23 121 85 160 1.06 90 50 170 .62 31 20 180 .25 5B.D.C. 4.00 0 185.5 0 0 190 .17 200 .46 210 .77 220 1.12 230 1.42 -2 240 1.80 -4 -4 250 2.02 -8 -21 260 2.15 -45 -50 270 2.18 -109 -76 280 2.02 -154 -104 290 1.74 -181 -124 300 1.46 -181 -131 310 1.07 -140 -147 320 .81 -119 -165 330 .67 -111 -179 340 .46 -82 -187 350 .24 -450 -190 360 0 0__________________________________________________________________________
TABLE IV______________________________________CALCULATION OF TOTAL TORQUE DUE TOCYLINDER PRESSURE AT EACH INCREMENTCRANKSHAFT TOTALROTATION CYLINDER NO. TORQUEDEGREES 1 2 3 4 5 6 VALUES______________________________________10 163 180 -8 33520 299 138 -45 39230 401 121 -109 41340 442 90 -154 37850 458 31 -181 30860 446 5 -181 27070 462 0 -140 32280 498 -119 37990 477 -111 366100 446 -82 364110 364 -45 319120 224 0 224______________________________________
Initially, with knowledge of the engine stroke, estimated values of minimum and maximum crankpin offsets may be selected to permit computational testing using Tables III and IV and well known geometric relationships to start the iterative process and, ultimately, derive optimum crankpin offsets. Since the maximum and minimum crankpin offsets achieved during a rotation of the crankshaft will determine the piston stroke dimension and the stroke dimension is fixed for each engine (i.e., at 4 inches for the present example) the sum of the minimum and maximum crankpin offsets must equal the stroke dimension. A ratio of approximately 30:70 of the stroke dimension for the minimum and maximum crankpin offsets, respectively, has been found to be a reasonably close initial ratio for beginning computational testing for the six cylinder engine of the present example, thus resulting in an initial estimated CPO MIN of 1.20 and an initial estimated CPO MAX of 2.80. It has been found that an initial ratio closer to 1/4-3/4 is more appropriate for engines having fewer cylinders and/or higher compression ratios.
The initial estimated transition crankpin offset apexes TOA1 and TOA2 are then selected as follows. First, the circumferential position of TOA1 relative to CPO MIN is determined by initially selecting the angle during the power stroke at which the beginning of the transition from CPO MIN to CPO MAX will occur. At this angle, e.g. 65° ATDC, TOA1 will align with connecting rod centerline L, which extends through CPO MIN . The radial position of TOA1 along connecting rod centerline L can be determined by initially choosing a distance equal to 90% of CPO MAX . The product of this percentage and the maximum offset value equals the radial distance between TOA1 and the crankshaft axis 108 along connecting rod centerline L. The selection of the radial position of TOA1 controls the duration of the transition period, e.g., from 65°-110° ATDC. The circumferential position of TOA2 and the corresponding crankpin offset TO2 may be determined in a similar manner to that of TOA1 by initially choosing a desired angle for the beginning of the decreasing transition period from CPOA MAX to CPOA MIN during the compression stroke, e.g., 240° ATDC. The radial position of TOA2 along connecting rod centerline L can be determined by initially choosing a distance equal to 96% of CPO MAX . The product of this percentage and the maximum offset value equals the radial distance between TOA2 and the crankshaft axis 108 along connecting rod centerline L. The selection of the radial position of TOA2 controls the duration of the transition period, e.g., from 240°-310° ATDC. However, it has been found that for computational simplicity, initially, TOA1 and TOA2 may be assumed to be positioned on the respective outer surfaces 130 of rotators 122 and 124, respectively. If TOA1 is assumed to lie on the outer surface 130, then the corresponding crankpin offset dimensions TO1 and TO2 may be easily calculated from the geometry of the arrangement.
The moment arms for each increment in Table III are then calculated using the selected offsets in the following manner. The initially selected minimum crankpin offset CPO MIN of 1.20 inches is used to calculate the moment arm values for each of the displacement/rotational increments from 310°-65° ATDC while the initially selected maximum crankpin offset CPO MAX of 2.80 inches is used to calculate the moment arm values for each increment from 110°-240° ATDC. Using well known geometric relationships, the moment arm values during the transition periods may then be calculated using the increasing transition offset TO1 from 65°-110° ATDC and the decreasing transition offset TO2 from 240°-310° ATDC. The crankshaft torque for a single cylinder at each displacement increment may then be calculated from the corresponding cylinder pressure using the moment arm values calculated for each increment. The crankshaft torque values are then transferred into the appropriate columns in Table IV for cylinders 1-6, assuming cylinder 1 at 0° TDC at the beginning of its power stroke, and summed to generate the total torque for each rotational increment. The total torque values at each increment can then be individually compared to the ideal mean torque value of 368 to determine the extent of the deviation of each total torque value. FIG. 3 illustrates a graphical comparison of the total torque values relative to the ideal mean torque value of 368 over 120 degrees. A comparison of the graph of FIG. 3 with the graph of FIG. 2 reveals that the use of minimum and maximum crankpin offsets of 1.20 and 2.80 results in a substantially more constant torque output than a fixed 2 inch crankpin offset. Based on a comparison of ideal mean torque 368 with the total torque values of Table IV, and FIG. 3, adjustments can be made to the initially selected minimum and maximum crankpin offset values, transition offset values, duration of the transition periods (i.e., by adjusting radial spacing of TOA1 and TOA2) and/or the timing of the beginning of the transition periods (i.e., by adjusting the circumferential position of TOA1 and TOA2). For example, referring to FIG. 1D, which illustrates the beginning of the increasing transition period, the timing of the beginning could be delayed in the rotation by designing rotator 122 to position TOA1 circumferentially to the left in FIG. 1D, or advanced by positioning TOA1 circumferentially to the right. The radial position of TOA1 and TOA2 affects the linear spacing between crankshaft axis 108 and the respective transition offset apex, thus affecting the respective transition crankpin offsets TO1, TO2 during the transition periods. Moreover, the radial position of TOA1 and TOA2 controls the duration of the respective transition periods. The closer TOA1 and TOA2 are to crankshaft axis 108 the slower the rate of change between CPOA MIN and CPOA MAX and therefore the greater the duration of the respective transition period, and vice versa. Therefore, the circumferential and radial positions of TOA1 and TOA2 can be varied during the iterative process of the present invention to modify the corresponding crankpin transition offsets, and the timing and duration of the transition periods, thus adding various degrees of control, in addition to the selection of CPO MIN and CPO MAX , in achieving an optimum torque output. After a new set of values is selected, the calculation is repeated and the total torque values at each increment resulting from these new offsets are again compared to the ideal mean torque of 368. As with any iterative calculation, this procedure may be repeated until the crankpin offset combination, including minimum, maximum and transition values, best reproducing the net mean torque value of 368, i.e., the deviation of the actual torque from the ideal mean torque value is minimized, is achieved.
Although the present method as discussed hereinabove with respect to Tables I-IV and FIGS. 2-3 achieves relatively consistent engine torque output, the preceding embodiment of the method only considered the effects of cylinder gas pressure on the resulting torque. However, effects and forces other than gas pressure effects can alter the output torque. Therefore, if desired, these other effects may be considered in the determination of the crankpin offsets using the method of the present invention.
An example of an effect likely to be deemed inconsequential in most instances and, therefore, justifiably ignored during design, would be the work and torque required to operate the cylinder valves at particular displacement increments. On the other hand, an example of an effect likely to be deemed of consequence, would be the inertial force effects caused by the reciprocating motion of each piston/connecting rod assembly. These inertial effects include both positive and negative forces acting on the crankpin during each stroke of each piston. As a result, the inertial force magnitudes change continuously, possibly reaching magnitudes comparable to the gas pressure force. Consequently, the second embodiment of the present method, as described with respect to Tables V and VI, and FIGS. 4 and 5, includes the consideration of these inertial forces on the output torque.
TABLE V__________________________________________________________________________INCREMENTAL INERTIAL FORCE CALCULATIONFOR SINGLE CYLINDER TORQUE TORQUECHANGE IN TOTAL DUE TO CRANKSHAFT DUE TOKINETIC KINETIC INERTIAL DISPLACEMENT ROTATION CYLINDER MOMENT GASENERGY ENERGY FORCE FROM TOC DEGREES PRESSURE ARM PRESSURE__________________________________________________________________________0 0 0 0 0 700 0 00 0 0 10 680 .24 163(1.0) 1.0 (5) 20 650 .46 299(1.7) 2.7 (9) 30 599 .67 401(3.0) 5.7 (16) 40 539 .82 442(2.3) 8.0 (13) 50 477 .96 458(1.3) 9.3 (7) 60 421 1.06 446(4.4) 13.7 (24) 70 350 1.32 462(11.5) 25.2 (63) 80 291 1.71 498(12.1) 37.3 (67) 90 236 2.02 477(8.4) 45.7 (46) 100 194 2.30 446(9.2) 54.9 (51) 110 155 2.35 364+9.2 45.7 +51 120 134 1.67 224+8.4 37.3 +46 130 120 1.50 180+9.9 27.4 +54 140 105 1.31 138+8.4 19.0 +46 150 98 1.23 121+8.3 10.7 +46 160 85 1.06 90+6.0 4.7 +32 170 50 .62 31+2.4 2.3 +13 180 20 .25 5+2.3 0 +13 4 185.5 B.D.C. 0 0 00 0 0 190 .17(1.0) 1.0 (5) 200 .46(1.5) 2.5 (8) 210 .77(6.8) 9.3 (37) 220 1.12(9.7) 19.0 (53) 230 1.42(8.4) 27.4 (46) 240 -2 1.80 -4(24.4) 51.8 (134) 250 -4 2.02 -8(36.1) 87.9 (199) 260 -21 2.15 -45(12.7) 100.6 (70) 270 -50 2.18 -109+24.5 76.1 +135 280 -76 2.02 -154+36.1 40.0 +199 290 -104 1.74 -181+22.8 17.2 +125 300 -124 1.46 -181+12.5 4.7 +69 310 -131 1.07 -140+3.7 1.0 +20 320 -147 .81 -119(2.0) 3.0 (11) 330 -165 .67 -l110 3.0 0 340 -179 .46 -82+2.0 1.0 +11 350 -187 .24 -45+1.0 0 +5 0 360 -190 0 0__________________________________________________________________________
TABLE VI__________________________________________________________________________CALCULATION OF COMBINED TOTAL TORQUE AT EACH INCREMENT A B TOTAL TOTAL C TORQUE TORQUE COMBINEDCRANKSHAFT CYLINDER NO. TORQUE DUE TO DUE TO DUE TO TOTALROTATION GAS/INERTIAL FORCES INERTIAL CYLINDER TORQUEDEGREES 1 2 3 4 5 6 FORCES PRESSURE VALUES__________________________________________________________________________10 163/0 180/46 -8/(134) (88) 335 24720 299/(5) 138/54 -45/(199) (150) 392 24230 401/(8) 121/46 -109/(70) (32) 413 38140 442/(16) 90/46 -154/135 165 378 54350 458/(13) 31/32 -181/199 218 308 52660 446/(7) 5/13 -181/125 131 270 40170 462/(24) 0/13 -140/69 58 322 38080 498/(63) 0/(5) -119/20 (48) 379 33190 477/(67) 0/(8) -111/(11) (86) 366 280100 446/(46) 0/(37) -82/0 (83) 364 281110 364/(51) 0/(53) -45/11 (93) 319 226120 224/51 0/(48) 0/5 10 224 234__________________________________________________________________________
Although any engine may be used in the present method, for illustrative purposes the engine used to calculate the values in Tables V and VI is assumed to be operating at a normal speed of 2000 RPM, and utilizing a normal piston/connecting rod assembly weighing two pounds. As a result, this piston/connecting rod assembly possesses 100 foot-pounds of potential inertial energy (kinetic energy) at approximately 90° after and 90° before its 0° top dead center position. Also, the assembly possesses zero foot-pounds of potential inertial energy at approximately 0° TDC and 180° BDC. The fluctuating torque due to the changes in inertial energy is also experienced by the crankpin assembly 104.
Table V represents in column form the calculation of these inertial forces for each 10° increment of the 360° cycle, including the change in the kinetic energy during the total displacement. For illustrative purposes the values of the offsets have been selected as follows: CPO MIN =1.2; CPO MAX =2.8; TO1=2.44 from 65° to 109° ATDC; TO2=2.70 from 240° to 312° ATDC. Using conventional relationships, the inertial force on the crankpin can be calculated for each increment. Using the known preset minimum, maximum, and transition crankpin offsets, the moment arm for each increment, as previously explained, can be calculated. The product of the calculated moment arm for each increment and the inertial force acting on the crankpin is the torque on the crankshaft at each increment due solely to the reciprocating type inertial effects of the piston/connecting rod assembly. These inertia induced crankshaft torque values are then transferred into the columns in Table VI for the appropriate cylinders and summed to generate the total torque induced by all six of the piston/connecting rod assemblies at each rotational increment (column A). Table VI also includes a column setting forth the total torque at each rotational increment due solely to gas pressure effects in the cylinders as determined in accordance with the method described hereinabove with respect to Tables III and IV (column B). The total gas pressure induced torque values (column B) are then summed with the total inertia induced torque values (column A) for each increment to obtain the combined total torque values (column C). The combined total torque values at each increment at normal operating speed are then compared to the torque values experienced at idle or low operating speeds wherein inertial effects on the output torque are insignificant. These combined torque values are also compared to the ideal mean torque value of 368. This comparison can be performed graphically as illustrated in FIG. 4. As can be seen, the gas pressure induced torque curve, for the present engine having a variable crankpin offset, indicates a more consistent torque output than the fixed crankpin offset arrangement of FIG. 2. This improvement in the torque output consistency will improve engine efficiency and reduce the fuel required per horsepower hour by an estimated 29%. However, this improved condition becomes less advantageous at higher operating speeds where the output torque deviates from the ideal mean torque in a significantly different way due to the non-linear effects of inertial forces, as indicated by the combined total torque curve. For example, the deviation from the ideal torque has most noticeably increased at approximately 30°-60°. With respect to possible ways of minimizing these deviations, particularly, when one of the combined total torque values and the gas pressure induced torque values is higher than the ideal mean torque and the other torque value is lower than the ideal mean torque at the same displacement point, i.e. at approximately 30° and 60° as shown in FIG. 4, with the torque values positioned on opposite sides of the ideal mean torque value line, then changing the crankpin offsets will not function to bring the output torque at both idle and high speeds closer to the ideal mean torque.
However, the deviation of the overall total torque curve may be decreased by altering the engine design to reduce the ratio of the inertial effects to the ideal mean torque. One way of decreasing the inertial effects is to increase the bore-to-stroke ratio. By increasing the bore and decreasing the stroke, the velocity, and therefore the kinetic energy, at each displacement increment, will be decreased thus reducing the inertial force of the piston/connecting rod assembly. For example, for the engine of the previous embodiment, if the stroke is decreased 20% and the bore area is correspondingly increased, i.e., 25%, in order to maintain the cubic inch displacement constant, and the torque value calculations previously described are repeated, a significant reduction in the inertial effects is achieved as illustrated in FIG. 5. FIG. 5 was generated by calculating the total inertial-induced torque and the total gas pressure induced torque values using the same procedure as described hereinabove with respect to Tables V and VI. As can be seen, by increasing the bore-to-stroke ratio and thus decreasing the inertial effects, the actual torque output at both high and low speeds more closely approximates the ideal mean torque. It is noteworthy that the mean torque per square inch of bore area of 281 closely approximates the 368 ideal mean torque per square inch of bore area when both are multiplied by their respective bore areas. The crankpin offsets may then be adjusted, using the above described method, to determine whether the deviation from the ideal mean torque can be further reduced. Of course, the calculating, estimating and comparing steps described hereinabove, required to achieve the optimum bore-to-stroke ratio and crankpin offsets, could be most easily accomplished via an appropriate computer algorithm. FIGS. 6A-6H illustrate another embodiment of the variable offset connection of the present invention, indicated generally at 200, which is similar to the embodiment of FIGS. 1A-1J in many respects, but includes a modified crankpin assembly 202. Referring to FIGS. 6A and 6B, the crankpin assembly has been modified to include a rotator bearing sleeve 204 having an aperture 206 formed therein for receiving a crankpin 208. Importantly, rotator bearing sleeve 204 includes an uninterrupted, continuous outer bearing surface 210 for sliding movement relative to connecting rod bearing surface 118. The uninterrupted, continuous outer bearing surface 210 is achieved by forming a rotator 212 integrally with sleeve 204 on one side, and providing a transition roller assembly 214 on the opposite side. Transition roller assembly 214, as described more fully hereinbelow, effectively permits the transition between the maximum crankpin offset (CPO MAX ) and the minimum crankpin offset (CPO MIN ) without the use of a rotator positioned in the same plane as integral rotator 212. Thus, transition roller assembly 214 is positioned in a plane adjacent to the plane in which bearing sleeve 204 is positioned to permit outer bearing surface 210 to extend in an uninterrupted manner around the entire circumference of connecting rod bearing surface 118. This design avoids unnecessary scoring and wearing of bearing surface 118, crankpin bearing surfaces 132, 134 and the outer surfaces 130 of rotators 122, 124 of the previous embodiment due to the practical difficulty in forming and positioning separate rotators and a crankpin so that their outer surfaces provide a smooth transition between the components at the interface of their bearing surfaces. As a result, the present embodiment significantly reduces the maintenance costs of the assembly in addition to the time and costs associated with manufacturing and positioning the components.
As shown in FIGS. 6A and 6B, rotator bearing sleeve 204 includes an inner support 216 forming a sleeve inner bearing surface 218 for slidably engaging a complementary shaped pivot surface 220 formed on crankpin 208. As with the first embodiment, integral rotator 212 includes an inner surface 222 slidably positioned in a concavity 224 formed in crankpin 208. When transitioning from the minimum crankpin offset to the maximum crankpin offset as illustrated in FIGS. 6C-6E, connecting rod 102 and rotator bearing sleeve 204 pivot around TOA1 causing inner surface 222 of rotator 212 to pivot relative to crankpin 208 while bearing surface 220 slides along sleeve inner bearing surface 218 until the maximum crankpin offset is reached as shown in FIG. 6E. Thus, although rotator 212 is formed integrally with bearing sleeve 204, the transition from minimum to maximum crankpin offsets is essentially the same as in the previous embodiment of FIGS. 1A-1J, including the alignment of TOA1 with the connecting rod center line to initiate the transition toward the maximum crankpin offset. Also, the determination of the position of TOA1 and the determination of the positions of CPOA MIN and CPOA MIN are the same as in the previous embodiment.
Transition roller assembly 214 includes a transition roller 226 pivotally mounted on the transverse support 138. Transition roller 226 includes a concavity 228 shaped to receive guide pin 141 which extends from connecting rod 102 into guide groove 135. Transition roller 226 engages a portion of bearing sleeve 204 via an indexing mechanism 230, e.g., a gear arrangement, formed between bearing sleeve 204 and transition roller 226, which causes transition roller 226 to be rotatably indexed during the transition periods as connecting rod 102 and bearing sleeve 204 pivot relative to one another. Indexing mechanism 230 includes gear pin 231 formed on transition roller 226 and gear recesses 233 formed in an adjacent surface of rotator bearing sleeve 204 for engagement by gear pin 231.
In FIG. 6A, the connecting rod 102 is shown in its outermost position with the engine piston at its TDC position. The movement of the variable offset connection 200 from the position shown in FIG. 6A through the end of the increasing transition period is the same as that described with reference to the first embodiment of FIGS. 1A-1F, except that transition roller 214 is rotated by indexing mechanism 230 during the transition periods so as to position concavity 228 into a receiving position as shown in FIG. 6E. Referring to FIG. 6F, at some point during the rotation from bottom dead center to top dead center, guide pin 141 will move through guide groove 135 into engagement with concavity 228 of transition roller 226. As the crankshaft continues to rotate, transition roller 226 rotates to permit guide pin 141 to continue to move through guide groove 135 as connecting rod 102 and bearing sleeve 204 shift inwardly toward crankshaft 106 thus moving the crankpin offset from CPO MAX CPO MIN . Referring to FIG. 6I, in this embodiment the circumferential and radial position of TOA1 and the corresponding crankpin offset may be determined as in the previous embodiment. Likewise, the circumferential position of TOA2 and the corresponding crankpin offset TO2 may be determined by initially choosing a desired angle for the beginning of the decreasing transition period from CPOA MAX to CPOA MIN during the compression stroke, e.g., 240° ATDC. The radial position of TOA2 along connecting rod centerline L can be determined by initially choosing a distance equal to 96% of CPO MAX . The product of this percentage and the maximum offset value equals the radial distance between TOA2, located at the center of rotation of transition roller 226, and the crankshaft axis 108 along connecting rod centerline L, e.g., 2.70 in the illustrative example presented herein. The selection of the radial position of TOA2 controls the duration of the transition period, e.g., from 240°-310° ATDC.
Thus, it can be seen that integral rotator 212 pivoting in concavity 224 and transition roller assembly 214 perform substantially the same functions as were performed by first and second transition rockers 122 and 124. Together, they effectively permit smooth transitional movement of connecting rod 102 relative to crankpin 208 and its rotator bearing sleeve 204 during each transition between CPO MIN and CPO MAX over a range of angular rotation while effectively transmitting forces between connecting rod 102 and its crankpin 208. As a result, the moment arm can be optimally varied, as in the FIGS. 1A-1J embodiment, resulting in an output torque from the engine, during each increment of rotation, which more closely approximates an optimum constant torque. Moreover, the embodiment of FIGS. 6A-6H accomplishes this objective while avoiding the practical problem of transitioning between multiple bearing surfaces and the attendant disadvantage of scoring and wearing the connector rod bearing surfaces.
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An improved engine output shaft includes a crankpin assembly for operatively connecting the shaft to each reciprocating piston for translating the reciprocating motion of each piston to rotary motion of the shaft through a leverage arm between the axis of rotation of the shaft and the point of operative connection between each piston and the shaft. The crankpin assembly is fixed to rotate with the shaft and defines a plurality of fixed crankpin offsets and transition offsets which sequentially vary the moment arm in a predetermined manner during the rotation of the shaft to produce a substantially constant total engine torque output during each increment of rotational movement. A method for making the improved engine output shaft comprises the steps of providing aforedescribed crankpin assembly, determining a target value for total torque output for each increment of engine output rotation, selecting first estimated values for each of the plurality of fixed crankpin and transition offsets, calculating the engine output torque for each rotational increment for a single cylinder, summing the torque contributions and demands for all cylinders at each increment of shaft rotation to determine the total torque output for each increment, comparing the total torque output with the target value for each increment, selecting second estimated values for each of the plurality of fixed crankpin and transition offsets based upon the observed deviation from the target torque value and repeating the calculations until the selected offsets satisfactorily reproduce the target torque value.
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CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional of U.S. patent application Ser. No. 11/624,990, filed Jan. 19, 2007, the disclosure of which is incorporated by reference herein in its entirety.
FIELD OF THE INVENTION
[0002] This invention relates to audio and visual multimedia processing systems and particularly to methodologies for editing time and annotated multimedia data.
DESCRIPTION OF BACKGROUND
[0003] Before our invention there were many situations when it is necessary to create a transcription of a multimedia file, wherein the transcription of the multimedia file was synchronized with the original multimedia file. This situation was particularly relevant in fields pertaining to the transcribing and/or translation of multimedia video data, the maintaining of media databases, and the preparation of caption data for televised programming.
[0004] Presently, transcripts of multimedia data are created using either automatic speech recognition (ASR), and/or automatic translation tools. Unfortunately, initial draft transcriptions that have been generated by ASR often have the need to be edited in order to provide the correct textual representation of an original media data stream file. Typically, as a result of the editing process, the time-alignment between various media streams and the edited transcribed/translated text is destroyed. Therefore, there exists a need to provide a cost-effective, standard user-based methodology for the editing of time aligned transcripts, annotations to the time aligned transcripts and translations of the transcripts.
SUMMARY
[0005] The shortcomings of the prior art are overcome and additional advantages are provided through the provision of a method for editing timed and annotated data, the method further comprising the steps of acquiring a multimedia data stream, segmenting the multimedia stream into a video data and an audio data stream, wherein the playback times of the video and audio data streams are synchronized, associating playback time annotation indicators with the time synchronized video and audio data streams, wherein discrete playback time annotation indicators of the video data stream segments correlate with discrete playback time annotation indicators of the audio data stream segments, and creating a transcript of the audio data stream.
[0006] The method further comprises the steps of associating the discrete playback time annotation indicators of the audio data stream words, or phrases that are reproduced within the audio data stream with respective corresponding textual representations of the words, or phrases that are comprised within the transcript, editing the transcript of the audio data stream, and outputting the transcript, the video data and audio data streams in a predetermined data format.
[0007] System and computer program products corresponding to the above-summarized methods are also described and claimed herein.
[0008] Additional features and advantages are realized through the techniques of the present invention. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention. For a better understanding of the invention with advantages and features, refer to the description and to the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The subject matter that is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
[0010] FIG. 1 illustrates one example of a diagram illustrating aspects of functional components that may be implemented within embodiments of the present invention.
[0011] FIG. 2 illustrates one example of a GUI, wherein the GUI displays a screenshot of a window for an editable transcription stream, and a window for a multimedia file that is time-synchronized with the transcription stream.
[0012] FIG. 3 illustrates one example of an HTML formatted output that is displayed within a web browser, wherein the multimedia file and the transcription stream are time-synchronized.
[0013] The detailed description explains the preferred embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
DETAILED DESCRIPTION
[0014] One or more exemplary embodiments of the invention are described below in detail. The disclosed embodiments are intended to be illustrative only since numerous modifications and variations therein will be apparent to those of ordinary skill in the art.
[0015] Currently, many situations occur when it is necessary to create, and synchronize a transcription of a multimedia file (i.e., files containing audio and video data components) with the original multimedia file (e.g., transcripts or translations of video files, media databases, captions of television programs, etc . . . ). ASR and automatic translation tools can be used to create initial draft transcriptions of a multimedia file. However, the transcription drafts that are generated by theses tools more so than not will require the further editing of the transcription in order to provide the correct textual representation of the content that has been derived from the original multimedia file. A further, complication that may occur during the editing process of a transcription, is that the time alignment/synchronization that has been established between the multimedia files and a transcription media file is destroyed.
[0016] Thus, aspects of the present invention relate to the editing of transcription data that has been associated with a multimedia data file, while concurrently providing for the preservation of any annotated synchronization data that relates to the transcription data and a respective multimedia file. These aspects of the present invention are automatically accomplished, therefore allowing for the unrestricted editing of time aligned transcription data. And further, the preservation of any time alignment specifications is ensured between the transcription and multimedia data files, without placing any undue burden upon an editing system operator to manually maintain the time alignment annotation between a transcription data file and a multimedia data file. Aspects of the present invention additionally allow for the provision of additional feedback information to an editing system operator, wherein the feedback information is based upon timing information that is associated with edited text pronunciation, which in turn can be used to improve the annotation editing process.
[0017] The present invention is implemented within a computing system environment. The computer system can be a conventional personal computer. As is conventional, the computer can also include hardware and software elements conventionally included in personal computers, wherein the software elements of the programmed computer can comprise elements such as application specific windows, or browsers. The computer system has other hardware and software elements of the types conventionally included in personal computers, such as an operating system. Note, that software components implemented within embodiments of the present invention can be loaded into the computer via read/write storage devices or a network.
[0018] Turning now to the drawings in greater detail, it will be seen that in FIG. 1 there is a block diagram detailing aspects of an embodiment of the present invention. The methodologies of the present invention are initiated by the acquisition of a multimedia data stream file 100 , wherein thereafter the multimedia data stream file is separated into its respective media data stream files 105 (i.e., an audio data stream and a video data stream). The respective data stream files that comprise the multimedia data stream are configured to comprise comprehensive time alignment data relating to the data streams, in addition to any annotated information that is associated with the data streams.
[0019] At block 110 , a transcription of the audio data stream file is created from the audio data stream; wherein the transcription can be configured as a standard transcription of the audio data stream, a translation of the audio data stream, a listing of annotations that are associated with the audio data stream, or a summarization of the audio data stream. The transcription can be created using any conventionally available ASR conversion tool. The transcription comprises synchronization information that relates the textual elements of the transcription with the original multimedia data stream file from which the transcription was derived. In further aspects of the present invention, a transcriber can manually create a transcription, wherein the transcription can be created with, or without synchronization information that relates the timing of the transcription with the timing information of the original multimedia data stream file.
[0020] The transcription created at block 110 is input to an aligned transcription/multimedia stream editor 115 . The aligned transcription/multimedia stream editor 115 comprises an editing software component 120 , and an alignment-approximating component 130 . The primary function of the editing component 120 is to perform any required transcription text and annotation editing operations. All editorial changes are reported to the alignment-approximating component 130 , wherein the alignment-approximating component ensures that the annotated synchronization information relating to the edited transcription is properly aligned with the synchronization information that relates to the multimedia data stream information.
[0021] In further aspects of the present invention, software allowing very fine letter based segmentation, wherein the segmentation is based upon clearly aligned multimedia data to textual data. Further, interpolation that is based on approximation up to the letter level, is implemented in order to edit a transcription, or to add additional details to the annotation information for a transcription. For example, in the event that annotation information describing pitch or emotions, or annotation information that contains translation information for a transcription is necessitated, the existing alignment of the edited transcription and the multimedia data is kept intact. Software component 115 comprises the capability to respectively represent individual characters within a transcription, and annotated information that is associated with a respective character. Annotated information can include, but is not limited to character information, character timing information and character annotation information. In the event that one or more characters are to be inserted into the text of a transcription, then the final calculations in regard to the timing information that is associated with the inserted text is determined based upon on the timing information that is associated with the characters that surround/border the inserted text.
[0022] With aspects of the present invention, annotation information comprises structured timing information, wherein the timing information details how the general timing flow of the multimedia data would be affected by the insertion of the edited data. Structured timing data is currently defined as data that contains timing data for different multimedia data playback speeds (e.g., fast, slow, medium). The insertion of this time data into the overall processing flow relates to the use of contextual data in the determination of the overall speed of the audio/video media data at the editing point. Further, each time an editing operation is performed upon a transcription, the alignment-approximation for the edited transcription data to the multimedia data is recalculated.
[0023] In the event that it is determined that the quality of the transcription text, and the synchronization with the multimedia stream is sufficient, the annotated and/or transcribed multimedia stream information is outputted into a desired data format (e.g., an XML, HTML file or database).
[0024] Yet further aspects of the present invention allow for the provision of feedback to a system user based upon the timing information that is associated with the edited pronunciation of transcription text, which in its turn can also be used to improve the annotation editing process. FIG. 2 shows a screenshot of an editable transcription stream that is synchronized with a media data stream file. The screenshot shows a GUI 200 , wherein the GUI 200 is used to display and edit time-aligned transcriptions. The left-side display 205 , displays the text of a transcription. All of the textual character data of the transcription is associated with annotated timing information. The right-side display 210 is configured to playback a multimedia data file. The right-side display 210 further comprises multimedia controls, thus allowing for the control of the listening/viewing aspects of a multimedia data.
[0025] During a multimedia data playback operation, transcription text that is time associated with the multimedia data file is highlighted 230 at the left-side display. The highlighted text 230 is associated with the current playback time position 220 of the multimedia data. The playback speed of the multimedia data and the playback length of the multimedia data file are also respectively shown at 225 and 215 . The present application further allows for the editing of a transcript in conjunction with the simultaneous listening and viewing of a multimedia data stream file. The timing information that is embedded into the transcription allows for the navigation from the edited text of the transcription to a relational playback position of the media file, and from the playback position of the media file to the text of the transcription during the editing process. A system user has only to select a character, word, or phrase in the text, and the multimedia file will travel to the corresponding synchronized point within the multimedia playback. Conversely, a user can select a multimedia data playback position, and the text that is synchronized with the playback position of the multimedia file will accordingly be highlighted.
[0026] FIG. 4 shows outputted HTML formatted multimedia and transcription time-synchronized data streams. The screenshot of a browser 300 represents sample output data, demonstrating one of many benefits of having transcription text synchronized with a multimedia data stream file. In this example, the annotated timing information that is, embedded into the transcription text was used to generate an HTML (DHTML) application. The multimedia playback window 310 on the left side of the browser 300 is associated with the highlighted text 330 on the right side 305 to show the current text. As mentioned above, a system user also can click on any text on the right side 305 to make the playback of the multimedia data stream file travel to a corresponding position. Thus, an automatic generation of the HTML application is made possible due to the dynamic real-time editing of the transcription text data.
[0027] The capabilities of the present invention can be implemented in software, firmware, hardware or some combination thereof.
[0028] As one example, one or more aspects of the present invention can be included in an article of manufacture (e.g., one or more computer program products) having, for instance, computer usable media. The media has embodied therein, for instance, computer readable program code means for providing and facilitating the capabilities of the present invention. The article of manufacture can be included as a part of a computer system or sold separately.
[0029] The flow diagram depicted herein is just an example. There may be many variations to the diagram or the steps (or operations) described therein without departing from the spirit of the invention. For instance, the steps may be performed in a differing order, or steps may be added, deleted or modified. All of these variations are considered a part of the claimed invention.
[0030] While the preferred embodiment to the invention has been described, it will be understood that those skilled in the art, both now and in the future, may make various improvements and enhancements which fall within the scope of the claims which follow. These claims should be construed to maintain the proper protection for the invention first described.
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A method for editing timed and annotated data includes acquiring a multimedia data stream; performing a decoding operation upon the multimedia data stream, wherein the decoded data stream comprises a textual data stream; synchronizing the multimedia data stream and the decoded data stream by performing a time stamping operation upon the data streams; editing the decoded data stream; and realigning the time stamp data of the edited decoded data stream in order to synchronize the edited decoded data with the multimedia data stream.
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FIELD OF THE INVENTION
This invention generally relates to the derivatives of novel 3,6-disubstituted azabicyclo[3.1.0]hexanes.
The compounds of this invention are muscarinic receptor antagonists which are useful, inter-alia, for the treatment of various diseases of the respiratory, urinary and gastrointestinal systems mediated through muscarinic receptors.
The invention also relates to pharmaceutical compositions containing the compounds of the present invention and the methods of treating the diseases mediated through muscarinic receptors.
BACKGROUND OF THE INVENTION
Muscarinic receptors as members of the G Protein Coupled Receptors (GPCRS) are composed of a family of 5 receptor sub-types (M 1 , M 2 , M 3 , M 4 and M 5 ) and are activated by the neurotransmitter acetylcholine. These receptors are widely distributed on multiple organs and tissues and are critical to the maintenance of central and peripheral cholinergic neurotransmission. The regional distribution of these receptor sub-types in the brain and other organs has been documented. For example, the M 1 subtype is located primarily in neuronal tissues such as cereberal cortex and autonomic ganglia, the M 2 subtype is present mainly in the heart where it mediates cholinergically induced bradycardia, and the M 3 subtype is located predominantly on smooth muscle and salivary glands ( Nature , 1986; 323: 411; Science, 1987; 237: 527).
A review in Current opinions in Chemical Biology, 1999; 3: 426, as well as in Trends in Pharmacological Sciences, 2001; 22: 409 by Eglen et. al., describe the biological potentials of modulating muscarinic receptor subtypes by ligands in different disease conditions like Alzheimer's disease, pain, urinary disease condition, chronic obstructive pulmonary disease etc.
A review in J. Med. Chem., 2000; 43: 4333 by Christian C. Felder et. al. describes therapeutic opportunities for muscarinic receptors in the central nervous system and elaborates on muscarinic receptor structure and function, pharmacology and their therapeutic uses.
The pharmacological and medical aspects of the muscarinic class of acetylcholine agonists and antagonists are presented in a review in Molecules, 2001, 6: 142.
N. J. M. Birdsall et. al. in Trends in Pharmacological Sciences, 2001; 22: 215 have also summarized the recent developments on the role of different muscarinic receptor subtypes using different muscaranic receptor of knock out mice.
Muscarinic agonists such as muscarine and pilocarpine and antagonists such as atropine have been known for over a century, but little progress has been made in the discovery of receptor subtype-selective compounds making it difficult to assign specific functions to the individual receptors. Although classical muscarinic antagonists such as atropine are potent bronchodilators, their clinical utility is limited due to high incidence of both peripheral and central adverse effects such as tachycardia, blurred vision, dryness of mouth, constipation, dementia, etc. Subsequent development of the quarterly derivatives of atropine such as ipratropium bromide are better tolerated than parenterally administered options but most of them are not ideal anti-cholinergic bronchodilators due to lack of selectivity for muscarinic receptor sub-types. The existing compounds offer limited therapeutic benefit due to their lack of selectivity resulting in dose limiting side-effects such as thirst, nausea, mydriasis and those associated with the heart such as tachycardia mediated by the M 2 receptor.
Annual review of Pharmacological Toxicol., 2001; 41: 691, describes the pharmacology of the lower urinary tract infections. Although anti muscarinic agents such as oxybutynin and tolterodine that act non-selectively on muscarinic receptors have been used for many years to treat bladder hyperactivity, the clinical effectiveness of these agents has been limited due to the side effects such as dry mouth, blurred vision and constipation. Tolterodine is considered to be generally better tolerated than oxybutynin. (W. D. Steers et. al. in Curr. Opin. Invest. Drugs, 2: 268, C. R. Chapple et. al. in Urology, 55: 33), Steers W D, Barrot D M, Wein A J, 1996, Voiding dysfunction: diagnosis classification and management. In Adult and Pediatric Urology, ed. J Y Gillenwatter, J T Grayhack, S S Howards, J W Duckett, pp 1220-1325, St. Louis, Mo.; Mosby. 3 rd edition.)
Despite these advances, there remains a need for development of new highly selective muscarinic antagonists which can interact with distinct subtypes, thus avoiding the occurrence of adverse effects.
Compounds having antagonistic activity against muscarinic receptors have been described in Japanese patent application Laid. Open Number 92921/1994 and 135958/1994; WO 93/16048; U.S. Pat. No. 3,176,019; GB 940,540; EP 0325 571; WO 98/29402; EP 0801067; EP 0388054; WO 9109013; U.S. Pat. No. 5,281,601. U.S. Pat. Nos. 6,174,900, 6,130,232 and 5,948,792; WO 97/45414 are related to 1,4-disubstituted piperidine derivatives; WO 98/05641 describes fluorinated, 1,4-disubstitued piperidine derivatives; WO 93/16018 and WO96/33973 are other close art references.
A report in J. Med. Chem., 2002; 44:984, describes cyclohexylmethyl piperidinyl triphenylpropioamide derivatives as selective M 3 antagonist discriminating against the other receptor subtypes.
SUMMARY OF THE INVENTION
The present invention provides novel 3,6-disubstituted azabicyclo[3.1.0]hexanes as muscarinic receptor antagonists which are useful as safe and effective therapeutic or prophylactic agents for the treatment of various diseases of the respiratory, urinary and gastrointestinal systems, and process for the synthesis of the novel compounds.
The invention also provides pharmaceutical compositions containing the novel compounds together with acceptable carriers, excipients or diluents which are useful for the treatment of various diseases of the respiratory, urinary and gastrointestinal systems.
The present invention also includes within its scope prodrugs of the novel compounds. In general, such prodrugs will be functionalized derivatives of these compounds which readily get converted in vivo into the defined compounds. Conventional procedures for the selection and preparation of suitable prodrugs are known to the artisan skilled in the art.
The invention also includes the enantiomers, diastereomers, N-oxides, polymorphs, pharmaceutically acceptable salts and pharmaceutically acceptable solvates of these compounds as well as metabolites having the same type of activity.
The invention further includes pharmaceutical compositions comprising the compounds of the present invention, their prodrugs, metabolites, enantiomers, diastereomers, N-oxides, polymorphs, solvates or pharmaceutically acceptable salts thereof, in combination with a pharmaceutically acceptable carrier and optionally included excipients.
Other advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description or may be learnt by the practice of the invention. The objects and the advantages of the invention may be realized and obtained by means of the mechanisms and combinations pointed out in the appended claims.
In accordance with one aspect of the present invention, there is provided a compound having the structure of Formula I:
and its pharmaceutically acceptable salts, pharmaceutically acceptable solvates, esters, enantiomers, diastereomers, N-oxides, polymorphs, prodrugs, metabolites, wherein Ar represents an aryl or a heteroaryl ring having 1-2 hetero atoms selected from the group consisting of oxygen, sulphur and nitrogen atoms, the aryl or heteroaryl rings may be unsubstituted or substituted by one to three substituents independently selected from lower alkyl (C 1 -C 4 ), lower perhalo alkyl (C 1 -C 4 ), cyano, hydroxy, nitro, lower alkoxy (C 1 -C 4 ), lower perhalo alkoxy (C 1 -C 4 ), unsubstituted amino, N-lower alkyl (C 1 -C 4 ) amino or N-lower alkyl (C 1 -C 4 ) amino carbonyl;
R 1 represents a hydrogen, hydroxy, hydroxy methyl, amino, alkoxy, carbamoyl or halogen (e.g. fluorine, chlorine, bromine and iodine); R 2 represents aLkyl, C 3 -C 7 cycloalkyl ring, a C 3 -C 7 cyclo alkenyl ring, an aryl or a heteroaryl ring having 1 to 2 hetero atoms selected from a group consisting of oxygen, sulphur and nitrogen atoms; the aryl or a heteroaryl ring may be unsubstituted or substituted by one to three substituents independently selected from lower alkyl (C 1 -C 4 ), lower perhalo alkyl (C 1 -C 4 ), cyano, hydroxy, nitro, lower alkoxycarbonyl, halogen, lower alkoxy (C 1 -C 4 ), lower perhalo alkoxy (C 1 -C 4 ), unsubstituted amino, N-lower alkylamino (C 1 -C 4 ), N-lower alkylamino carbonyl (C 1 -C 4 ); W represents (CH 2 ) p , where p represents 0 to 1; X represents an oxygen, sulphur, nitrogen or no atom; Y represents CHR 5 CO wherein R 5 represents hydrogen or methyl or (CH 2 )q wherein q represents 0 to 4; Z represents oxygen, sulphur, NR 10 , wherein R 10 represents hydrogen, C 1-6 alkyl; Q represents (CH 2 ) n wherein n represents 0 to 4, or CHR 8 wherein R 8 represents H, OH, C 1-6 , alkyl, alkenyl alkoxy or CH 2 CHR 9 wherein R 9 represents H, OH, lower alkyl (C 1 -C 4 ) or lower alkoxy (C 1 -C 4 ); R 6 and R 7 are independently selected from COOH, H, CH 3 , CONH 2 , NH 2 , CH 2 NH 2 ; R 4 represents C 1 -C 15 saturated or unsaturated aliphatic hydrocarbon groups in which any 1 to 6 hydrogen atoms may be substituted with the group independently selected from halogen, arylalkyl, arylalkenyl, heteroarylalkyl or heteroarylalkenyl having 1 to 2 hetero atoms selected from a group consisting of nitrogen, oxygen and sulphur atoms with option that any 1 to 3 hydrogen atoms on the ring in said arylalkyl, arylalkenyl, hetero arylalkenyl group may be substituted with lower alkyl (C 1 -C 4 ), lower perhalo alkyl (C 1 -C 4 ), cyano, hydroxyl, nitro, lower alkoxycarbonyl, halogen, lower alkoxy (C 1 -C 4 ), lower perhaloalkoxy (C 1 -C 4 ), unsubstituted amino, N-lower alkylamino (C 1 -C 4 ), N-lower alkylamino carbonyl (C 1 -C 4 ).
In accordance with a second aspect of the present invention, there is provided a compound having the structure of Formula II (Formula I, when R 6 and R 7 ═H) and its pharmaceutically acceptable salts, pharmaceutically acceptable solvates, esters, enantiomers, diastereomers, N-oxides, polymorphs, prodrugs, metabolites, wherein Ar, R 1 , R 2 , W, X, Y, Z, Q, and R 4 are as defined for Formula I.
In accordance with a third aspect of the present invention, there is provided a compound having the structure of Formula III (Formula I wherein W is (CH 2 )p where p=0, X is no atom and Y is (CH 2 )q where q=0, R 6 ═H, R 7 ═H) and its pharmaceutically acceptable salts, pharmaceutically acceptable solvates, esters, enantiomers, diastereomers, N-oxides, polymorphs, prodrugs, metabolites, wherein Ar, R 1 , R 2 , Z, Q and R 4 are as defined for Formula I.
In accordance with a fourth aspect of the present invention, there is provided a compound having the structure of Formula IV (Formula I wherein W is (CH 2 )p where p=0, X is no atom and Y is (CH 2 )q where q=0, R 6 ═H, R 7 ═H,
and its pharmaceutically acceptable salts, pharmaceutically acceptable solvates, esters, enantiomers, diastereomers, N-oxides, polymorphs, prodrugs, metabolites, wherein Ar, R 1 , Z, Q and R 4 are as defined for Formula I and r is 1 to 4.
In accordance with a fifth aspect of the present invention, there is provided a compound having the structure of Formula V (Formula I wherein W is (CH 2 )p where p=0, X is no atom and Y is (CH 2 )q where q=0, R 6 ═H, R 7 ═H,
R 1 is hydroxy, Ar is phenyl), and its pharmaceutically acceptable salts, pharmaceutically acceptable solvates, esters, enantiomers, diastereomers, N-oxides, polymorphs, prodrugs, metabolites, wherein R 4 , Z and Q are the same as defined for Formula I, s represents 1 to 2.
In accordance with a sixth aspect of the present invention, there is provided a method for treatment or prophylaxis of an animal or a human suffering from a disease or disorder of the respiratory, urinary and gastrointestinal systems, wherein the disease or disorder is mediated through muscarinic receptors.
In accordance with a seventh aspect of the present invention, there is provided a method for treatment or prophylaxis of an animal or a human suffering from a disease or disorder associated with muscarinic receptors, comprising administering to a patient in need thereof, an effective amount for muscarinic receptor antagonist compound as described above.
In accordance with an eighth aspect of the present invention, there is provided a method for treatment or prophylaxis of an animal or a human suffering from a disease or disorder of the respiratory system such as bronchial asthma, chronic obstructive pulmonary disorders (COPD), pulmonary fibrosis, etc.; urinary system which induce such urinary disorders as urinary incontinence, lower urinary tract symptoms (LUTS), etc.; and gastrointestinal system such as irritable bowel syndrome, obesity, diabetes and gastrointestinal hyperkinesis with compounds as described above, wherein the disease or disorder is associated with muscarinic receptors.
In accordance with a ninth aspect of the present invention, there are provided processes for preparing the compounds as described above.
The compounds of the present invention are novel and exhibit significant potency in terms of their activity, which was determined by in vitro receptor binding and functional assays and in vivo experiments using anaesthetized rabbit. The compounds that were found active in in vitro assay were tested in vivo. Some of the compounds of the present invention were found to be potent muscarinic receptor antagonists with high affinity towards M 3 receptors. Therefore, the present invention provides the pharmaceutical compositions for the possible treatment for the disease or disorders associated with muscarinic receptors. In addition, the compounds of the present invention can be administered orally or parenterally.
DETAILED DESCRIPTION OF THE INVENTION
The compounds of the present invention may be prepared by techniques well known in the art and familiar to the average synthetic organic chemist. In addition, the compounds of the present invention may be prepared by the following novel and inventive reaction sequences:
The compounds of Formula I of the present invention may be prepared by the reaction sequence as shown in Scheme I. The preparation comprises condensing a compound of Formula VII with the compound of Formula VI wherein Ar represents an aryl or a heteroaryl ring having 1-2 hetero atoms selected from the group consisting of oxygen, sulphur and nitrogen atoms, the aryl or heteroaryl rings may be unsubstituted or substituted by one to three substituents independently selected from lower alkyl (C 1 -C 4 ), lower perhalo alkyl (C 1 -C 4 ), cyano, hydroxy, nitro, lower alkoxy (C 1 -C 4 ), lower perhalo alkoxy (C 1 -C 4 ), unsubstituted amino, N-lower alkyl (C 1 -C 4 ) amino or N-lower alkyl (C 1 -C 4 ) amino carbonyl;
R 1 represents a hydrogen, hydroxy, hydroxy methyl, amino, alkoxy, carbamoyl or halogen (e.g. fluorine, chlorine, bromine and iodine); R 2 represents alkyl, C 3 -C 7 cycloalkyl ring, a C 3 -C 7 cyclo alkenyl ring, an aryl or a heteroaryl ring having 1 to 2 hetero atoms selected from a group consisting of oxygen, sulphur and nitrogen atoms; the aryl or a heteroaryl ring may be unsubstituted or substituted by one to three substituents independently selected from lower alkyl (C 1 -C 4 ), lower perhalo alkyl (C 1 -C 4 ), cyano, hydroxy, nitro, lower alkoxycarbonyl, halogen, lower alkoxy (C 1 -C 4 ), lower perhalo alkoxy (C 1 -C 4 ), unsubstituted amino, N-lower alkylamino (C 1 -C 4 ), N-lower alkylamino carbonyl (C 1 -C 4 ); W represents (CH 2 ) p , where p represents 0 to 1; X represents an oxygen, sulphur, nitrogen or no atom; Y represents CHR 5 CO wherein R 5 represents hydrogen or methyl or (CH 2 )q wherein q represents 0 to 4; Z represents oxygen, sulphur, NR 10 , wherein R 10 represents hydrogen, C 1-6 alkyl; Q represents (CH 2 ) n wherein n represents 0 to 4, or CHR 8 wherein R 8 represents H, OH, C 1-6 , alkyl, alkenyl alkoxy or CH 2 CHR 9 wherein R 9 represents H, OH, lower alkyl (C 1 -C 4 ) or lower alkoxy (C 1 -C 4 ); R 6 and R 7 are independently selected from COOH, H, CH 3 , CONH 2 , NH 2 , CH 2 NH 2 ; P is any protecting group for an amino group, in the presence of a condensing agent to give a protected compound of Formula VIII which on deprotection in the presence of a deprotecting agent in an organic solvent gives an unprotected intermediate of Formula IX which is finally N-alkylated or benzylated with a suitable alkylating or benzylating agent L-R 4 to give a compound of Formula I wherein L is any leaving group and R 4 is as defined above. P is any protecting group for an amino group for a compound of Formula VI and is selected from benzyl and t-butyloxy carbonyl groups.
The reaction of the compound of Formula VII with a compound of Formula VI to give a compound of Formula VIII is carried out in the presence of a condensing agent which is selected from the group consisting of 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride (EDC) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU).
The reaction of the compound of Formula VII with a compound of Formula VI to give a compound of Formula VIII is carried out in a suitable solvent selected from the group consisting of N,N-dimethylformamide, dimethylsulfoxide, toluene, and xylene at a temperature ranging from about 0-140° C.
The deprotection of the compound of Formula VIII to give a compound of Formula IX is carried out with a deprotecting agent which is selected from the group consisting of palladium on carbon, trifluoroacetic acid (TFA) and hydrochloric acid.
The deprotection of the compound of Formula VIII to give a compound of Formula IX is carried out in a suitable organic solvent selected from the group consisting of methanol, ethanol, tetrahydrofuran and acetonitrile at temperatures ranging from about 10-50° C.
The N-alkylation or benzylation of the compound of Formula IX to give a compound of Formula I is carried out with a suitable alkylating or benzylating agent, L-R 4 wherein L is any leaving group, known in the art, preferably selected from halogen, O-mestyl and O-tosyl group.
The N-alkylation or benzylation of the compound of Formula IX to give a compound of Formula I is carried out in a suitable organic solvent such as N,N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran and acetonitrile, at temperatures ranging from about 25-100° C.
In the above scheme, where specific bases, condensing agents, protecting groups, deprotecting agents, N-alkylating/benzylating agents, solvents, catalysts etc. are mentioned, it is to be understood that other bases, condensing agents, protecting groups, deprotecting agents, N-alkylating/benzylating agents, solvents, catalysts etc. known to those skilled in the art may be used. Similarly, the reaction temperature and duration may be adjusted according to the desired needs.
Alternatively, the compounds of the invention may be prepared by condensing compounds of formula VI with an aryl alpha keto ester (Ar(CO)COOR′ wherin R′ denotes a lower alkyl group) and the compounds thus formed may be subsequently reacted with the condensate R″M, wherein R″ groups include groups such as phenyl, C4-6 alkyl etc. and M may be alkali metal or MgX, wherein x is a halogen atom. Alpha keto esters may in turn be prepared by following J.O.C., 46, 213(1981), or synthetic communication, 11, 943(1981).
The compounds of the invention may also be prepared by reacting R″M (wherein M and R″ have the same as described above) with the aryl alpha keto ester (Ar(CO)COOR′ wherin R′ denotes a lower alkyl group) to form an alpha hydroxy ester. This product is further reacted with compound of formula VI and then the protecting group is removed to give compounds of formula VIII.
Suitable salts of the compounds represented by the Formula I were prepared so as to solubilize the compound in aqueous medium for biological evaluations. Examples of such salts include pharmacologically acceptable salts such as inorganic acid salts (e.g. hydrochloride, hydrobromide, sulphate, nitrate and phosphorate), organic acid salts(e.g. acetate, tartarate, citrate, fumarate, maleate, tolounesulphonate and methanesulphonate). When carboxyl group is included in the Formula I as a substituent, it may be an alkali metal salt(e.g. sodium, potassium, calcium, magnesium, and the like). These salts may be prepared by the usual prior art techniques, such as treating the compound with an equivalent amount of inorganic or organic, acid or base in a suitable solvent.
Preferred compounds according to the invention and capable of being produced by Scheme I as shown in Table-I include:
Compound
No.
Chemical Name
1.
(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-
6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide
2.
(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-
6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-
phenyl acetamide
3.
(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-
6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-
phenyl acetamide
4.
(1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-
6-(methyl)-yl]-2-hydroxy-2,2-diphenyl acetate
5.
(1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-
6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate
6.
(1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-
6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl
acetate
7.
(1α,5α,6α)-[3-(2-(2,3-dihydrobenzofuran-
5-yl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-
yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate
8.
(1α,5α,6α)-[3-(2-(2,3-dihydrobenzofuran-
5-yl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-
yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate
9.
(1α,5α,6α)-N-[3-(2-(2,3-dihydrobenzofuran-
5-yl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-
yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide
10.
(1α,5α,6α)-N-[3-(2-(2,3-dihydrobenzofuran-
5-yl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-
yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide
11.
(1α,5α,6α)-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-
3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-
2-cyclopentyl-2-phenyl acetate
12.
(1α,5α,6α)-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-
3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-
2-cyclohexyl-2-phenyl acetate
13.
(1α,5α,6α)-N-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-
3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-
hydroxy-2-cyclopentyl-2-phenyl acetamide
14.
(1α,5α,6α)-N-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-
3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-
hydroxy-2-cyclohexyl-2-phenyl acetamide
15.
(1α,5α,6α)-N-[3-(4-methyl-3-pentenyl)-3-
azabicyclo[3.1.0]hexyl-6-(aminomethyl)-
yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide
16.
(1α,5α,6α)-N-[3-(4-methyl-3-pentenyl)-3-
azabicyclo[3.1.0]hexyl-6-(aminomethyl)-
yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide
17.
(1α,5α,6α)-[3-(4-methyl-3-pentenyl)-3-
azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-
hydroxy-2-cyclohexyl-2-phenyl acetate
18.
(1α,5α,6α)-[3-(4-methyl-3-pentenyl)-3-
azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-
hydroxy-2-cyclopentyl-2-phenyl acetate
19.
(1α,5α,6α)-[3-(1-phenylethyl)-3-azabicyclo[3.1.0]hexyl-
6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate
20.
(1α,5α,6α)-[3-(1-phenylethyl)-3-azabicyclo[3.1.0]hexyl-
6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate
21.
(1α,5α,6α)-N-[3-(1-phenylethyl)-3-azabicyclo[3.1.0]hexyl-
6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl
acetamide
22.
(1α,5α,6α)-N-[3-(1-phenylethyl)-3-azabicyclo[3.1.0]hexyl-
6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl
acetamide
23.
(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-
6-(1-aminoethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide
24.
(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-
6-(1-aminoethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl
acetamide
25.
(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-
6-(1-aminoethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl
acetamide
26.
(1α,5α,6α)-[3-(3-methyl-2-butenyl)-3-
azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-
hydroxy-2-cyclohexyl-2-phenyl acetate
27.
(1α,5α,6α)-[3-(3-methyl-2-butenyl)-3-
azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-
hydroxy-2-cyclopentyl-2-phenyl acetate
28.
(2R)-(+)-(1α,5α,6α)-N-[3-benzyl-3-
azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-
hydroxy-2-cyclohexyl-2-phenyl acetamide
29.
(2R)-(+)-(1α,5α,6α)-N-[3-benzyl-3-
azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-
hydroxy-2-cyclopentyl-2-phenyl acetamide
30.
(2R)(+)-(1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-
6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate
31.
(2R)(+)-(1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-
6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate
32.
(2S)-(−)-(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-
6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl
acetamide
33.
(2S)-(−)-(1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-
6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate
34.
(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-
6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl
acetamide L-(+)-tartrate salt
35.
(2S)-(−)-(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-
6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl
acetamine. L-(+)-tartrate salt
36.
(2R)-(+)-(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-
6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl
acetamide. L-(+)-tartrate salt
37.
(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-
6-(aminomethyl)-yl]-2-hydroxy-2-cyclobutyl-2-phenyl
acetamide
38.
(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-
6-(aminomethyl)-yl]-2-hydroxy-2-cyclopropyl-2-phenyl
acetamide
39.
(1α,5α,6α)-N-[3-(3-methyl-2-butenyl)-3-
azabicyclo[3.1.0]hexyl-6-(aminomethyl)-
yl]-2-hydroxy-2-hexyl-2-phenyl acetamide
40.
(1α,5α,6α)-[3-(3,4-methylenedioxyphenyl)methyl-
3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-
2-cyclopentyl-2-phenyl acetate
41.
(1α,5α,6α)-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-
3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-
2-cyclopentyl-2-phenyl acetate. L-(+)-tartrate salt
42.
(1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-
6-(methyl)-yl]-2-hydroxy-2,2 diphenyl acetate L(+)-
tartrate salt
43.
(1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-
6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl
acetate L(+)-tartrate salt
44.
(1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-
6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl
acetate L(+)-tartrate salt.
45.
(1α,5α,6α)-N-[3-(3-pyridylmethyl)-3-
azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-
2-hydroxy-2-cyclohexyl-2-phenyl acetamide
46.
(1α,5α,6α)-N-[3-(4-pyridylmethyl)-3-
azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-
2-hydroxy-2-cyclohexyl-2-phenyl acetatamide
47.
(1α,5α,6α)-N-[3-(2-pyridylmethyl)-3-
azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-
2-hydroxy-2-cyclohexyl-2-phenyl acetamide
48.
(1α,5α,6α)-N-[3-(4-pyridylmethyl)-3-
azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-
2-hydroxy-2-cyclopentyl-2-phenyl acetamide
49.
(1α,5α,6α)-N-[3-(3-pyridylmethyl)-3-
azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-
2-hydroxy-2,2-diphenyl acetamide
50.
(1α,5α,6α)-N-[3-(4-pyridylmethyl)-3-
azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-
2-hydroxy-2,2-diphenyl acetamide
51.
(1α,5α,6α)-N-[3-(2-pyridylmethyl)-3-
azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-
2-hydroxy-2,2-diphenyl acetamide
52.
(1α,5α,6α)-N-[3-(2-pyridylmethyl)-3-
azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-
2-hydroxy-2-cyclopentyl-2-phenyl acetamide
53.
(1α,5α,6α)-N-[3-(3-pyridylmethyl)-3-
azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-
2-hydroxy-2-cyclopentyl-2-phenyl acetamide
54.
(1α,5α,6α)-N-[3-(3-methyl-2-butenyl)-
3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-
yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide
55.
(1α,5α,6α)-N-[3-(3,4-methylenedioxyphenyl)methyl-
3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-
hydroxy-2-cyclopentyl-2-phenyl acetamide
56.
(1α,5α,6α)-N-[3-(3,4-methylenedioxyphenyl)methyl-
3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-
hydroxy-2-cyclohexyl-2-phenyl acetamide
57.
(1α,5α,6α)-[3-(4-methyl-3-pentenyl)-3-
azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-
cyclohexyl-2-phenyl acetate-L-(+) tartrate salt
58.
(1α,5α,6α)-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-
3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-
2-cyclohexyl-2-phenyl acetate. L-(+) tartrate salt
59.
(1α,5α,6α)-[3-(1-phenylethyl)-3-
azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-
2-cyclopentyl-2-phenyl acetate. L-(+) tartrate salt
60.
(1α,5α,6α)-N-[3-benzyl-3-azabicyclo [3.1.0]-
hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-
2-phenyl acetamide hydrochloride salt
61.
(1α,5α,6α)-N-[3-benzyl-3-azabicyclo [3.1.0]-
hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-
2-phenyl acetamide L-(−) malic acid salt
62.
(1α,5α,6α)-N-[3-benzyl-3-azabicyclo [3.1.0]-
hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-
2-phenyl acetamide maleate salt
TABLE I
Formula III
(Formula I, wherein W = (CH 2 )p where p = 0, X is no atom and
Y = (CH 2 )q, where q = 0, R 6 = R 7 = H)
Compound
No.
Ar
R 1
R 2
Z
Q
R 4
1.
OH
NH
CH 2
2.
OH
NH
CH 2
3.
OH
NH
CH 2
4.
OH
O
CH 2
5.
OH
O
CH 2
6.
OH
O
CH 2
7.
OH
O
CH 2
8.
OH
O
CH 2
9.
OH
NH
CH 2
10.
OH
NH
CH 2
11.
OH
O
CH 2
12.
OH
O
CH 2
13.
OH
NH
CH 2
14.
OH
NH
CH 2
15.
OH
NH
CH 2
16.
OH
NH
CH 2
17.
OH
O
CH 2
18.
OH
O
CH 2
19.
OH
O
CH 2
20.
OH
O
CH 2
21.
OH
NH
CH 2
22.
OH
NH
CH 2
23.
OH
NH
CHCH 3
24.
OH
NH
CHCH 3
25.
OH
NH
CHCH 3
26.
OH
O
CH 2
27.
OH
O
CH 2
28
OH
NH
CH 2
29
OH
NH
CH 2
30
OH
O
CH 2
31
OH
O
CH 2
32
OH
NH
CH 2
33
OH
O
CH 2
34
L-(+) Tartaric acid salt of compound shown in Compound Number 3 in this
table
35
L-(+) Tartaric acid salt of compound shown in Compound Number 32 in
this table
36
L-(+) Tartaric acid salt of compound shown in Compound Number 29 in
this table
37
OH
NH
CH 2
38
OH
NH
CH 2
39
OH
NH
CH 2
40
OH
O
CH 2
41
L (+)-Tartrate salt of compound shown in Compound Number 11 of this
table
42
L (+)-Tartrate salt of compound shown in Compound Number 4 of this
table
43
L (+)-Tartrate salt of compound shown in Compound Number 5 of this
table
44
L (+)-Tartrate salt of compound shown in Compound Number 6 of this
table
45
OH
NH
CH 2
46
OH
NH
CH 2
47
OH
NH
CH 2
48
OH
NH
CH 2
49
OH
NH
CH 2
50
OH
NH
CH 2
51
OH
NH
CH 2
52
OH
NH
CH 2
53
OH
NH
CH 2
54
OH
NH
CH 2
55
OH
NH
CH 2
56
OH
NH
CH 2
57
L-(+) Tartaric salt of compound 17
58
L-(+) Tartaric salt of compound 12
59
L-(+) Tartrate salt of compound No. 19
60
Hydrochloride salt of compound No. 3
61
L-(−) Malic acid salt of compound No. 3
62
Maleate salt of compound No. 3
Because of their valuable pharmacological properties, the compounds of the present invention may be administered to an animal for treatment orally, or by parenteral route. The pharmaceutical compositions of the present invention are preferably produced and administered in dosage units, each unit containing a certain amount of at least one compound of the invention and/or at least one physiologically acceptable addition salt thereof. The dosage may be varied over extremely wide limits as the compounds are effective at low dosage levels and relatively free of toxicity. The compounds may be administered in the low micromolar concentration, which is therapeutically effective, and the dosage may be increased as desired up to the maximum dosage tolerated by the patient.
The present invention also includes within its scope prodrugs of the compounds of Formulae I, II, III, IV and V. In general, such prodrugs will be functional derivatives of these compounds, which readily are converted in vivo into the defined compounds. Conventional procedures for the selection and preparation of suitable prodrugs are known.
The present invention also includes the enantiomers, diastereomers, N-Oxides, polymorphs, solvates and pharmaceutically acceptable salts of these compounds as well as metabolites having the same type of activity. The present invention further includes pharmaceutical composition comprising the molecules of Formulae I, II, III, IV and V or prodrugs, metabolites, enantiomers, diastereomers, N-oxides, polymorphs, solvates or pharmaceutically acceptable salts thereof, in combination with pharmaceutically acceptable carrier and optionally included excipient.
The examples mentioned below demonstrate the general synthetic procedure as well as the specific preparation of the preferred compound. The examples are provided to illustrate the details of the invention and should not be constrained to limit the scope of the present invention.
Experimental Details
Various solvents, such as acetone, methanol, pyridine, ether, tetrahydrofuran, hexanes, and dichloromethane, were dried using various drying reagents according to the procedure described in the literature. IR spectra were recorded as nujol mulls or a thin neat film on a Perkin Elmer Paragon instrument, Nuclear Magnetic Resonance (NMR) were recorded on a Varian XL-300 MHz instrument using tetramethylsilane as an internal standard.
EXAMPLE 1
Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide (Compound No. 1)
Step a: Preparation of 2-hydroxy-2,2-diphenyl acetic acid
Synthesized as per reported procedures in Vogel's textbook of practical organic chemistry page 1046 (5 th Ed); J. Am. Chem. Soc ., 75, 2654(1953) and EP 613232.
Step b: Preparation of (1α,5α,6α)-6-aminomethyl-3-benzyl-3-azabicyclo[3.1.0]hexane
Synthesized as per reported procedures described in EP 0 413 455; U.S. Pat. No. 2,490,714 and Synlett, 1097-1102 (1996).
Step c: To a solution of (1α,5α,6α)-6-aminomethyl-3-benzyl-3-azabicyclo[3.1.0]hexane (1 mmol, 0.202 gm) in dimethyl formamide, DMF (5 ml) was added 2-hydroxy-2,2-diphenyl acetic acid (1 mmol, 0.225 gm) and cooled to 0° C. The reaction mixture was treated with hydroxy benzotriazole (1 mmol, 0.135 g) followed by N-methyl morpholine (2 mmol, 0.202 gm) and stirred at 0° C. for 0.5 hrs. EDC (1-[3-(dimethylamino)propyl]-3-ethyl carbodiimide hydrochloride (1 mmol, 0.192 gms) was added and the reaction mixture (RM) was stirred at 0° C. for 1 hour and at room temperature (RT) overnight. The RM was then poured into cold water and extracted with ethyl acetate. The combined organic layers were washed with water and dried over sodium sulphate. The crude compound obtained after removing the solvent was purified by column chromatography (silicagel 100-200 mesh), eluting the compound with 30-70 ethyl acetate-hexane mixture.
1 H-NMR (CDCl 3 ) δ—values:7.47-7.17 (m, arom, 15H), 3.58 (s, 2H, benzylic), 3.18-3.14 (t, 2H), 2.95-2.92 (d, 2H), 2.35-2.32 (m, 2H ), 2.04 (s, 1H) 1.28-1.23 (m, 1H), 0.94-0.91 (m, 2H)
IR (DCM): 1658 cm −1 (amide carbonyl)
EXAMPLE 2
Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide (Compound No. 2)
Step a: Preparation of 2-hydroxy-2-cyclohexyl phenyl acetic acid:
This was prepared following the procedure described in J. Amer. Chem. Soc. 75, 2654 (1953).
Step b: Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide
To a solution of (1α,5α,6α)-6-aminomethyl-3-benzyl-3-azabicyclo[3.1.0]hexane (1 mmol, 0.202 gm) in dimethyl formamide (5 ml) was added 2-hydroxy-2-cyclohexyl-2-phenylacetic acid (1 mmol, 0.234 gm) and cooled to 0° C. The reaction mixture was treated with hydroxy benzotriazole (1 mmol, 0.135 g) followed by N-methyl morpholine (2 mmol, 0.202 gm) and stirred at 0° C. for 0.5 hours. EDC (1 mmol, 0.192 gm) was then added. The reaction mixture (RM) after being stirred at 0° C. for 1 hour was later stirred at RT overnight. The RM was poured into cold water and extracted with ethyl acetate. The organic layer was dried and the crude product obtained after removing the solvent was purified by column chromatography (Silicagel 100-200 mesh) eluting the compound with 30-70 ethyl acetate-hexane mixture.
1 H-NMR: (CDCl 3 ) δ—values: 7.61-7.11 (m, 10H), 3.55 (s, 2H), 2.92-2.88 (m, 4H), 2.32-2.29 (m, 2H), 1.37-1.16 (m, 14H)
IR (DCM):1653 cm −1
EXAMPLE 3
Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No. 3)
Step a: Preparation of 2-hydroxy-2-cyclopentyl phenyl acetic acid:
This was prepared following the procedure described in J. Amer. Chem. Soc. 75, 2654 (1953).
Step b: Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide
To a solution of (1α,5α,6α)-6-aminomethyl-3-benzyl-3-azabicyclo[3.1.0]hexane (29.9 mmol, 6.05 gm) in dimethyl formamide (100 ml) was added 2-hydroxy-2-cyclopentyl-2-phenyl acetic acid (27.2 mmol, 6.0 gm) and cooled to 0° C. The reaction mixture was treated with hydroxy benzotriazole (29.9 mmol, 4.04 gm) followed by N-methyl morpholine (54.4 mmol, 5.2 gm) and was stirred at 0° C. for 0.5 hrs. The reaction mixture was poured into saturated bicarbonate solution and extracted with ethyl acetate. The organic layers were washed with water and dried over sodium sulphate and concentrated under reduced pressure. The residue was purified by column chromatography (silicagel 100-200 mesh) eluting compound with 20-80 to 25-75 ethyl acetate-hexane mixture. It gave a compound in 93-95% purity. To obtain higher purity (about 99%) of the compound it was triturated with toluene and filtered.
1 H-NMR: (CDCl 3 ) δ—values: 7.61-7.23 (m, 10H), 6.45 (bs,1H), 3.57 (s, 2H), 3.11-2.90 (m, 4H), 2.34-2.31 (m, 2H), 1.68-1.48 (m, 10H), 1.23 (m,2H).
MS: (M+1)=405.3
m.pt. 131-134° C.
IR (DCM): 1647, 1522, 1265 cm −1
EXAMPLE 4
Preparation of (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2,2-diphenyl acetate (Compound No. 4)
Step-a: Preparation of (1α,5α,6α)-3-benzyl-6-hydroxymethyl-3-azabicyclo[3.1.0]hexane synthesized as per reported procedure of EP 0 413 455 A2.
Step b: Preparation of (1α,5α,6α)-3-benzyl-6-(methanesulfonyloxy)methyl-3-azabicyclo[3.1.0]hexane:
A solution of the title compound of preparation of Step a of Compound 4 (0.203 g; 1 mmol) and triethylamine (0.21 gms, 2 mmol) in ethyl acetate (25 ml) was cooled to −10° C. and treated with methanesulfonyl chloride (0.17 gms, 1.5 mmol). After stirring for one hour at −10° C., the reaction was poured into a saturated aqueous sodium bicarbonate solution. The organic layer was dried over sodium sulphate. Filtration and removal of the solvent in vacuo provided the title compound as a yellow oil, which was used as such in the following step without further purification.
1 H-NMR (CDCl 3 ) δ—values: 7.45 (m, 5 H, arom.), 4.29 (s, 2H), 3.81 (m, 2H), 3.13 (m, 4H), 2.84 (s, 3H), 1.38 (m, 3H)
Step c: Preparation of (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2,2-diphenyl acetate:
To a solution of 2-hydroxy-2,2-diphenyl acetic acid (1 mmol, 0.228 gms) in xylene was added, (1α,5α,6α)-3-benzyl-6-(methanesulfonyloxy)methyl-3-azabicyclo[3.1.0]hexane: (0.28 gms, 1 mmol) followed by DBU (1,8-diazabicyclo[5,4,0]undec-7-ene, (2 mmol, 0.305 gms) and the reaction mixture refluxed for 6 hrs. The reaction mixture was then washed with water, brine and dried over sodium sulphate. The solvents were evaporated and the crude compound thus obtained was purified by column chromatography (silicagel, 100-200 mesh) eluting the compound with 20-80, ethyl acetate hexane mixture.
1 H-NMR (CDCl 3 ) δ—values: 7.46-7.22 (m, 15 H. arom.), 4.24 (s, 1H), 4.11-4.09 (d, 2H), 3.56 (s, 2H), 2.91-2.89 (d, 2H), 2.31-2.29 (d, 2H), 1.67-1.62 (m, 1H) 1.3 (s, 2H)
IR (DCM): 1724 cm −1
EXAMPLE 5
Preparation of (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate (Compound No. 5)
This compound was prepared following the procedure as in Example 4, step c using 2-hydroxy-2-cyclohexyl phenyl acetic acid instead of 2-hydroxy-2,2-diphenyl acetic acid.
1 H-NMR (CDCl 3 ) δ—values: 7.66-7.21 (m, 10 H, arom.), 4.09-3.92 (dd, 2H), 3.69 (s,2H), 2.93-2.89 (m, 2H), 2.33-2.30 (m, 3H), 1.65-1.12 (m, 13H)
IR (DCM): 1720 cm −1
EXAMPLE 6
Preparation of (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate (Compound No. 6)
This compound was prepared following the procedure as in Example 4, step c using 2 hydroxy-2-cyclopentyl phenyl acetic acid instead of 2-hydroxy-2,2-diphenyl acetic acid.
1 H-NMR (CDCl 3 ) δ—values: 7.67-7.20 (m, 10 H, arom.), 4.06-3.93 (dd, 2H), 3.57 (s,2H), 2.94-2.89 (m, 3H), 2.34-2.30 (m, 2H), 1.63-1.27 (m, 11H)
IR (DCM): 1718 cm −1
EXAMPLE 7
Preparation of (1α,5α,6α)-[3-(2-(2,3-dihydrobenzofuran-5-yl)ethyl-3-azabicyclo[3.1.0]hexyl-6(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate (Compound No. 7)
The compound obtained as in Example 5 was debenzylated and then N-alkylated as given below:
Step a: Preparation of (1α,5α,6α)-[3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate
A solution of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate (1 mmol) in methanol (50 ml), was added to a suspension of Pd/C (10%, 0.1 gm) and the reaction mixture was hydrogenated in Parr apparatus at 45 psi for 3 hrs. The reaction mixture was filtered and concentrated to afford the title compound.
1 H-NMR (CDCl 3 ) δ—values: 7.65-7.15 (m, 5 H, arom.), 4.14-4.02 (dd, 2H), 3.14-2.94-(m, 3H), 2.29-2.21 (m, 2H), 1.46-1.11 (m, 13H)
IR (KBr): 1723 cm −1
Step b: Preparation of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran Synthesized as per reported procedure of EP 0 388 054 A1,
Step c: To a solution of (1α,5α,6α)-[3-azabicyclo[3.1.0]hexyl-6-methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate (0.329 gms, 1 mmol) in dimethyl formamide (5 ml) was added potassium carbonate (2 mmol 0.276 gms), potassium iodide (1 mmol 0.166 gms) and 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran (0.275 gms, 1.2 mmol). The reaction mixture was stirred at room temperature overnight, poured into water and extracted with ethyl acetate. The combined organic layer was washed with water, brine and dried over sodium sulphate. The crude compound obtained after evaporation of the solvent under vacuum was purified by column chromatography (silica gel 100-200 mesh) eluting the compound with 20:80 ethyl acetate:hexane.
1 H-NMR (CDCl 3 ) δ—values: 7.67-6.67 (m, 8 H, arom.), 4.56-4.50 (m, 2H), 4.09-3.7-(dd, 2H), 3.19-3.01 (m, 4H), 2.62-2.60 (m, 3H), 2.33-2.30 (m, 4H), 1.65-1.11 (m, 13H)
IR (DCM): 1721 cm −1
EXAMPLE 8
Preparation of (1α,5α,6α)-[3-(2-(2,3-dihydrobenzofuran-5yl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate (Compound No. 8)
The compound obtained as in Example 6 was debenzylated and then N-alkylated as given below:
Step a: Preparation of (1α,5α,6α)-[3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate
A solution of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate (1 mmol) in methanol (50 ml), was added to a suspension of Pd/C (10%, 0.1 gm) and the reaction mixture was hydrogenated in Parr apparatus at 45 psi for 3 hrs. The reaction mixture was filtered and concentrated to afford the title compound.
1 H-NMR (CDCl 3 ) δ—values: 7.66-7.26 (m, 5 H, arom.), 4.15-4.01 (dd, 2H), 3.06-2.92-(m, 3H), 2.43-2.36 (m, 2H), 1.61-1.02 (m, 11H)
IR (KBr): 1721 cm −1
Step b: To a solution of compound (1α,5α,6α)-[3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetate (0.315 g, 1 mmol) in dimethyl formamide (5 ml) was added potassium carbonate (2 mmol, 0.276 gms), potassium iodide (1 mmol 0.166 gms) and 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran (0.275 gms, 1.2 mmol). The reaction mixture was stirred at room temperature overnight, poured into water and extracted with ethyl acetate. The combined organic layer was washed with water, brine and dried over sodium sulphate. The crude compound obtained after evaporation of the solvent under vacuum was purified by column chromatography (silica gel 100-200 mesh) eluting the compound with 20:80 ethyl acetate:hexane.
1 H-NMR (CDCl 3 ) δ—values: 7.68-6.67 (m, 8 H, arom.), 4.56-4.50 (m, 2H), 4.07-3.97-(dd, 2H), 3.19-3.02 (m, 4H), 2.33-2.30 (m, 6H), 1.37-1.25 (m, 11H)
IR (DCM): 1719 cm −1
EXAMPLE 9
Preparation of (1α,5α,6α)-N-[3-(2-(2,3-dihydrobenzofuran-5-yl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(amino methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide (Compound No. 9)
The compound obtained as in Example 2 was debenzylated and then N-alkylated as given below:
Step a: Preparation of (1α,5α,6α)-N-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide.
A solution of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide (1 mmol) in methanol (50 ml), was added to a suspension of Pd/C (10%, 0.1 gm) and the reaction mixture was hydrogenated in Parr apparatus at 45 psi for 3 hrs. The reaction mixture was filtered and concentrated to afford the title compound.
1 H-NMR (CDCl 3 ) δ—values: 7.62-7.26 (m, 5 H, arom.), 3.15-3.09 (m, 3H), 2.95-2.81-(m, 4H), 1.71-1.2 (m, 13H)
IR (KBr): 1656 cm −1
Step b: To solution of compound (1α,5α,6α)-N-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexylphenyl acetamide (0.328, 1 mmol) in dimethyl formamide (5 ml) was added potassium carbonate (2 mmol 0.276 gms), potassium iodide (1 mmol 0.166 gms) and 5-2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran (0.275 gms, 1.2 mmol). The reaction mixture was stirred at room temperature overnight, poured into water and extracted with ethyl acetate. The combined organic layer was washed with water, brine and dried over sodium sulphate. The crude compound obtained after evaporation of the solvent under vacuum was purified by column chromatography (silica gel 100-200 mesh) eluting the compound with 20:80 ethyl acetate:hexane.
1 H-NMR (CDCl 3 ) δ—values: 7.62-6.64 (m, 8H, arom.), 4.56-4.51 (t, 2H), 3.19-2.31 (m, 12H), 1.70-1.13 (m, 14H)
IR (DCM): 1654 cm −1 (amide carbonyl)
EXAMPLE 10
Preparation of (1α,5α,6α)-N-[3-(2-(2,3-dihydrobenzofuran-5-yl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No. 10)
The compound obtained as in Example 3 was debenzylated and then N-alkylated as given below:
Step a: Preparation of (1α,5α,6α)-N-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide
A solution of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (1 mmol) in methanol (50 ml), was added to a suspension of Pd/C (10%, 0.1 gm) and the reaction mixture was hydrogenated in Parr apparatus at 45 psi for 3 hrs. The reaction mixture was filtered and concentrated to afford the title compound.
1 H-NMR (CDCl 3 ) δ—values: 7.62-7.23 (m, 5 H, arom.), 3.13-3.07 (m, 2H), 2.95-2.81 (m, 5H), 1.34-0.87 (m, 11H)
IR (KBr): 1655 cm −1
Step b: To a solution of compound (1α,5α,6α)-N-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetamide (0.314 g, 1 mmol) in dimethyl formamide(5 ml) was added potassium carbonate (2 mmol 0.276 gms), potassium iodide (1 mmol 0.166 gms) and 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran (0.275 gms, 1.2 mmol). The reaction mixture was stirred at room temperature overnight, poured into water and extracted with ethyl acetate. The combined organic layer was washed with water, brine and dried over sodium sulphate. The crude compound obtained after evaporation of the solvent under vacuum was purified by column chromatography (silica gel 100-200 mesh) eluting the compound with 20:80 ethyl acetate:hexane.
1 H-NMR (CDCl 3 ) δ—values: 7.62-6.67 (m, 8H, arom.), 4.56-4.51 (t, 2H), 3.19-2.29 (m, 12H), 1.70-1.11 (m, 12H)
IR (KBr): 1657 cm −1
EXAMPLE 11
Preparation of (1α,5α,6α)-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate (Compound No. 11)
Step a: Preparation of 3,4-methylenedioxyphenethyl bromide
Synthesized as Per Reported Procedure of EP 0 388 054 A1
Step b: This compound was prepared following the procedure as in Example 8, step b, using 3,4-methylenedioxyphenethyl bromide instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran.
1 H-NMR (CDCl 3 ) δ—values: 7.8-6.6 (m, 8H, arom.), 6.0 (s, 2M), 4.2-3.9 (dd, 2H), 3.2-2.3 (m, 9H), 1.7-1.1 (m, 11H)
IR (DCM): 1720 cm −1
EXAMPLE 12
Preparation of (1α,5α,6α)-[3-(2-(3,4methylenedioxyphenyl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate (Compound No. 12)
This compound was prepared following the procedure as in Example 7, step c, using 3,4-methylenedioxyphenethyl bromide instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran.
1 H-NMR (CDCl 3 ) δ—values: 7.67-6.6 (m, 8H, arom.), 5.91 (s, 2H), 4.09-3.92 (dd, 2H), 3.03-2.99 (m, 2H), 2.61-2.59 (m, 4H), 2.32-2.28 (m, 4H) 1.65-1.1 (m, 12H).
IR (DCM): 1721 cm −1
EXAMPLE 13
Preparation of (1α,5α,6α)-N-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No. 13)
This compound was prepared following the procedure as in Example 10, Step b using 3,4-methylenedioxyphenethyl bromide instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran.
1 H-NMR (CDCl 3 ) δ—values: 7.61-6.59 (m, 8H, arom.), 5.91 (s, 2H), 3.05-2.27 (m, 11H), 1.66-1.24 (m, 11H)
IR (KBr): 1657 cm −1
EXAMPLE 14
Preparation of (1α,5α,6α)-N-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide (Compound No. 14)
This compound was prepared following the procedure as in Example 9, Step b using 3,4-methylenedioxyphenethyl bromide instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran.
1 H-NMR (CDCl 3 ) δ—values: 7.62-6.59 (m, 8H, arom.), 5.91 (s, 2H), 3.10-2.33 (m, 11H), 1.70-1.17 (m, 13H)
IR (DCM): 1653 cm −1
EXAMPLE 15
Preparation of (1α,5α,6α)-N-[3-(4-methyl-3-pentenyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide (Compound No. 15)
This compound was prepared following the procedure as in Example 9, Step b using 5-bromo-2-methyl-2-pentene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran.
1 H-NMR (CDCl 3 ) δ—values: 7.61-6.26 (m, 5H, arom.), 5.06 (t, 1H), 2.99-2.04 (m, 12H), 1.67-1.22 (m, 19H)
IR (DCM): 1656 cm −1
EXAMPLE 16
Preparation of (1α,5α,6α)-N-[3-(4-methyl-3-pentenyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No. 16)
This compound was prepared following the procedure as in Example 10, Step b using 5-bromo-2-methyl-2-pentene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran.
1 H-NMR (CDCl 3 ) δ—values: 7.61-7.25 (m, 5H, arom.), 5.06 (t, 1H), 3.06-2.04 (m, 12H), 1.67-1.1 (m, 16H)
IR (DCM): 1652 cm −1
EXAMPLE 17
Preparation of (1α,5α,6α)-[3-(4-methyl-3-pentenyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate (Compound No. 17)
This compound was prepared following the procedure as in Example 7, Step c using 5-bromo-2-methyl-2-pentene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran
1 H-NMR (CDCl 3 ) δ—values: 7.66-7.22 (m, 5H, arom.), 5.08 (t, 1H), 4.1-3.92 (dd, 2H), 3.0-2.97 (m, 2H), 2.27-2.08 (m, 7H), 1.65-1.11 (m, 19H)
IR (DCM): 1721 cm −1
EXAMPLE 18
Preparation of (1α,5α,6α)-[3-(4methyl-3-pentenyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate (Compound No. 18)
This compound was prepared following the procedure as in Example 8, Step b using 5-bromo-2-methyl-2-pentene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran.
1 H-NMR (CDCl 3 ) δ—values: 7.67-7.26 (m, 5H, arom.), 5.07 (t, 1H), 4.09-3.94 (dd, 2H), 3.01-2.08 (m, 9H), 1.68-0.97 (m, 17H)
IR (DCM): 1720 cm −1
EXAMPLE 19
Preparation of (1α,5α,6α)-[3-(1-phenylethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate (Compound No. 19)
This compound was prepared following the procedure as in Example 8, Step b using (1-bromoethyl)benzene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran.
1 H-NMR (CDCl 3 ) δ—values: 7.67-7.25 (m, 10H, arom.), 4.06-3.93 (dd, 2H), 3.24-2.08 (m, 6H), 1.6-1.23 (m, 15H)
IR (DCM): 1719 cm −1
EXAMPLE 20
Preparation of (1α,5α,6α)-[3-(1-phenylethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl-]-2-hydroxy-2-cyclohexyl-2-phenyl acetate (Compound No. 20)
This compound was prepared following the procedure as in Example 7, Step c using (1-bromoethyl)benzene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran.
1 H-NMR (CDCl 3 ) δ—values: 7.67-7.18 (m, 10H, arom.), 4.09-3.7 (dd, 2H), 3.24-2.11 (m, 4H), 2.63-2.37 (m, 8H), 1.64-1.1 (m, 11H)
IR (DCM): 1720 cm −1
EXAMPLE 21
Preparation of (1α,5α,6α)-N-[3-(1-phenylethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide (Compound No. 21)
This compound was prepared following the procedure as in Example 9, Step b using (1-bromoethyl)benzene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran.
1 H-NMR (CDCl 3 ) δ—values: 7.66-7.20 (m, 10H, arom.), 3.29-2.09 (m, 9H), 1.69-0.88 (m, 16H)
IR (KBr): 1653 cm −1
EXAMPLE 22
Preparation of (1α,5α,6α)-N-[3-(1-phenylethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No. 22)
This compound was prepared following the procedure as in Example 10, Step b using (1-bromoethyl)benzene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran.
1 H-NMR (CDCl 3 ) δ—values: 7.61-7.26 (m, 10H, arom.), 3.26-2.07 (m, 9H), 1.67-1.15 (m, 13H)
IR (DCM): 1651 cm −1
EXAMPLE 23
Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(1-aminoethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide (Compound No. 23)
Step a: Preparation of (1α,5α,6α)-6-(1-hydroxyethyl)-3-benzyl-3-azabicyclo[3.1.0]hexane: (1α,5α,6α)-3-benzyl-3-azabicyclo[3.1.0]hexane-6-carboxaldehyde (synthesized as per reported procedure of EP 0 413 455 A2, 2 gm, 100 mmol) was dissolved in tetrahydrofuran (400 ml) and cooled to −70° C. Methyllithium (105 mL of a 0.98 M solution in ether, 102 mmol) was added dropwise, stirred for one hour and later allowed to attain room temperature. Saturated aqueous ammonium chloride was added to the reaction mixture, the mixture was then extracted with ethyl acetate. The combined organic layers were dried over sodium sulphate, filtered and concentrated in vacuo to provide the product as a brown oil (yield 1.68 gm).
1 H-NMR (CDCl 3 ) δ—values: 7.26 (m, 5H, arom.), 3.59 (s, 2H), 3.16 (m, 1H), 2.97 (m, 2H), 2.35 (m, 2H), 1.39 (m, 1H), 1.24 (m, 5H)
Step b: Preparation of (1α,5α,6α)-3-benzyl-3-azabicyclo[3.1.0]hexane-6-methylketone
Dimethylsulphoxide (1.65 ml, 23 mmol) was added to a solution of oxalyl chloride (1.1 ml, 12.65 mmol) in methylene chloride (350 ml) maintained at −70° C. A solution of the title compound of preparation step a (2.5 gm, 11.5 mmol) in methylene chloride (50 ml) was then added to the reaction mixture at −70° C. After the addition of triethylamine (6.4 ml, 46 mmol), the mixture was allowed to warm to room temperature, water was added and the organic layer was collected, dried over sodium sulphate, filtered and concentrated to provide a light brown oil. Column chromatography (eluant: 20% ethyl acetate in hexane) provided the title compound (yield 1.4 gms).
1 H-NMR (CDCl 3 ) δ—values: 7.27 (m, 5H, arom.), 3.6 (s, 2H), 3.016 (m, 2H), 2.41 (m, 3H), 2.23 (s, 3H), 1.17 (m, 2H)
IR (DCM): 1694 cm −1
Step c: Preparation of (1α,5α,6α)-6-(1-aminoethyl)-3-benzyl-3-azabicyclo[3.1.0]hexane
To a stirred solution of the title compound of preparation step b (1.2 gms, 5.5 mmol) and ammonium acetate (1.28 gms, 16.6 mmol) in methanol (50 ml) was added sodium cyanoborohydride (0.87 gms, 43.75 mmol) at room temperature. The mixture was stirred for 18 hours at the same temperature. After the addition of saturated aqueous sodium bicarbonate, methanol was evaporated and the mixture was extracted three times with dichloromethane (100 ml). The combined organic extract was dried over sodium sulphate, filtered and concentrated under vacuo to obtain the crude compound (yield: 0.8 gms) which was used in the next step without purification.
1 H-NMR (CDCl 3 ) δ—values: 7.26 (m, 5H, arom.), 3.57 (s, 2H), 2.97 (m, 2H), 2.33 (m, 2H), 2.2 (m, 1H), 1.29 to 1.13 (m, 6H)
IR (DCM): 1654 cm −1
Step d: Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(1-aminoethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide:
The compound of Step-d was prepared by following the procedure described in step-c of Example 1 using (1α,5α,6α)-6-(1-aminoethyl)-3-benzyl-3-azabicyclo[3.1.0]hexane instead of (1α,5α,6α)-6-aminomethyl-3-benzyl-3-azabicyclo[3.1.0]hexane.
1 H-NMR (CDCl 3 ) δ—values: 7.33 (m, 15H. arom.), 6.16 (m, 1H), 3.56 (m, 2H), 3.43 (m, 1H), 2.88 (m, 2H), 2.31 (m, 2H), 1.40 (m, 1H), 1.29 to 1.13 (m, 5H)
IR (DCM): 1656 cm −1
EXAMPLE 24
Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(1-aminoethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide (Compound No. 24)
This compound was prepared by following the procedure described in Step-b of Example 2, using (1α,5α,6α)-6-(1-aminoethyl)-3-benzyl-3-azabicyclo[3.1.0]hexane instead of (1α,5α,6α)-6-aminomethyl-3-benzyl-3-azabicyclo[3.1.0]hexane.
1 H-NMR (CDCl 3 ) δ—values: 7.59 to 7.09 (m, 10H, arom.), 6.52 (m, 1H), 3.55 (m, 2H), 3.25 (m, 1H), 2.90 (m, 2H), 2.25 (m, 3H), 1.37 to 0.85 (m, 16H)
IR (DCM): 1651 cm −1
EXAMPLE 25
Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(1-aminoethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No. 25)
This compound was prepared by following the procedure described in Step-b of Example 3, using (1α,5α,6α)-6-(1-aminoethyl)-3-benzyl-3-azabicyclo[3.1.0]hexane instead of (1α,5α,6α)-6-aminomethyl-3-benzyl-3-azabicyclo[3.1.0]hexane.
1 H-NMR (CDCl 3 ) δ—values: 7.59 to 7.23 (m, 10H, arom.), 6.30 (m, 1H), 3.54 (s, 2H), 3.29 (m, 1H), 2.93 to 2.79 (m, 3H), 2.27 (m, 3H), 1.40 (m, 1H), 1.28 to 1.0 (m, 14H)
IR (DCM): 1651 cm −1
EXAMPLE 26
Preparation of (1α,5α,6α)-[3-(3-methyl-2-butenyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate (Compound No. 26)
This compound was prepared following the procedure as in Example 7, Step c using 1-bromo-3-methylbut-2-ene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran.
1 H-NMR (CDCl 3 ) δ—values: 7.66-7.23 (m, 5H, arom.), 5.19 (t, 1H), 4.08-3.89 (dd, 2H), 3.7 (s, 1H), 3.029-2.94 (m, 4H), 2.3-2.27 (m, 3H), 1.71-1.11 (m, 19H)
IR (DCM): 1721 cm −1
EXAMPLE 27
Preparation of (1α,5α,6α)-[3-(3-methyl-2-butenyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate (Compound No. 27)
This compound was prepared following the procedure as in Example 8, Step b using 1-bromo-3-methylbut-2-ene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran.
1 H-NMR (CDCl 3 ) δ—values: 7.67-7.23 (m, 5H, arom.), 5.19 (t, 1H), 4.05-3.91 (dd, 2H), 3.76 (s, 1H), 3.039-2.96 (m, 4H), 2.31-2.28 (m, 3H), 1.71-1.25 (m, 17H)
IR (DCM): 1721 cm −1
EXAMPLE 28
Preparation of (2R)-(+)-(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide (Compound No. 28)
Step a: Preparation of (2R)-(−)-2-hydroxy-2-cyclohexyl-2-phenyl acetic acid:
Synthesized as per reported procedure of Paul T. Grover, et. al. J. Org. Chem. 2000, 65, 6283-6287
Step b: The title compound was synthesised following the procedure as in step-b of Example 2, using (2R)-(−)-2-hydroxy-2-cyclohexyl-2-phenylacetic acid instead of 2-hydroxy-2-cyclohexyl-2-phenylacetic acid.
1 H-NMR (CDCl 3 ) δ—values: 7.61-7.22 (m, 10H, arom.), 6.62 (m, 1H), 3.55 (s, 2H), 3.26-2.07 (m, 9H), 1.67-1.15 (m, 13H)
[α] 25±3° C. =+3.85° (0.9846% MeOH)
IR (DCM): 1651 cm −1
EXAMPLE 29
Preparation of (2R)-(+)-(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No. 29)
Step a: Preparation of (2R)-(−)-2-hydroxy-2-cyclopentyl-2-phenyl acetic acid:
Synthesized as per reported procedure of Paul T. Grover, et. al. J. Org. Chem. 2000, 65, 6283-6287.
Step b: The title compound was synthesised following the procedure in step-b of Example 3, using (2R)-(−)-2hydroxy-2-cyclopentyl-2-phenyl acetic acid instead of 2-hydroxy-2-cyclopentyl-2-phenylacetic acid.
1 H-NMR (CDCl 3 ) δ—values: 7.61-7.26 (m, 10H, arom.), 3.26-2.07 (m, 9H), 1.67-1.15 (m, 13H)
IR (DCM): 1651 cm −1
[α] 25° C. =+3.95° (0.936% MeOH)
EXAMPLE 30
Preparation of (2R)(+)-(1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate (Compound No. 30)
Step a: Preparation of (2R)(−)2-hydroxy-2-cyclohexyl-2-phenyl acetic acid:
Synthesized as per reported procedure of Paul T. Grover, et. al. J. Org. Chem. 2000, 65, 6283-6287.
Step b: The title compound was synthesized following the procedure as in Example 4, step c using (2R)(−)-2-hydroxy-2-cyclohexyl-2-phenyl acetic acid instead of 2-hydroxy-2,2-diphenyl acetic acid.
1 H-NMR (CDCl 3 ) δ—values: 7.61-7.26 (m, 10H, arom.), 3.26-2.07 (m, 9H), 1.67-1.15 (m, 13H)
IR (DCM): 1651 cm −1
[α] 25° C. =+9.8° (1.09% MeOH)
EXAMPLE 31
Preparation of (2R)(+)-(1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate (Compound No. 31)
Step a: Preparation of (2R)(−)2-hydroxy-2-cyclopentyl-2-phenyl acetic acid:
Synthesized as per reported procedure of Paul T. Grover, et. al. J. Org. Chem. 2000, 65, 6283-6287.
Step b: The title compound was synthesised following the procedure as in Example 4, step c using (2R)(−)-2-hydroxy-2-cyclopentyl-2-phenylacetic acid instead of 2-hydroxy-2,2-diphenyl acetic acid.
1 H-NMR (CDCl 3 ) δ—values: 7.67-7.2 (m, 10H, arom.), 4.06 (m, 1H), 3.93 (m, 1H), 3.74 (s, 2H), 2.94-2.89 (m, 3H), 2.33-2.3 (m,2H), 1.64-1.29 (m, 11H)
IR (DCM): 1719 cm −1
[α]=+14.8° (1% MeOH)
EXAMPLE 32
Preparation of (2S)-(−)(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No. 32)
Step a: Preparation of (2S)(+)2-hydroxy-2-cyclopentyl-2-phenyl acetic acid:
Synthesized as per reported procedure of Paul T. Grover, et. al. J. Org. Chem. 2000, 65, 6283-6287.
Step b: The title compound was synthesised following the procedure in step-b of Example 3.
1 H-NMR (CDCl 3 ) δ—values: 7.62-7.25 (m, 10H. arom.), 6.45 (m, 1H), 3.58 (s, 2H), 3.07-2.92 (m, 5H), 2.35 (m, 2H), 1.77-1.24 (m, 11H)
IR (DCM): 1651 cm −1
[α]=−2.09° (1.1% MeOH)
EXAMPLE 33
Preparation of (2S)-(−)-(1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate (Compound No. 33)
Step a: Preparation of (2S)(+)2-hydroxy-2-cyclopentyl-2-phenyl acetic acid:
Synthesized as per reported procedure of Paul T. Grover, et. al. J. Org. Chem. 2000, 65, 6283-6287.
Step b: The title compound was synthesized following the procedure as in Example 4, Step c using 2S-(−)-2-hydroxy-2-cyclopentyl-2-phenylacetic acid instead of 2-hydroxy-2,2-diphenyl acetic acid.
1 H-NMR (CDCl 3 ) δ—values: 7.67-7.2 (m, 10H, arom.), 4.06 (m, 1H), 3.93 (m, 1H), 3.58 (s, 2H), 2.94-2.9 (m, 3H), 2.33-2.31 (m, 2H), 1.66-1.19 (m, 11H)
IR (DCM): 1720 cm −1
[α]=−14.9° (1.1% MeOH)
EXAMPLE 34
Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide L-(+)-tartrate salt (Compound No. 34)
(1α,5α,6α)-N-[3-benzyl-3-bicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No 3, 1 mmol) was dissolved in ethanol (10 ml) and a solution of L-(+)-tartaric acid (1 mmol) in ethanol (5 ml) was added and stirred at 60° C. for 1 hr. The reaction mixture was then concentrated by the evaporation of solvents under reduced pressure. The resulting solid was triturated with diethyl ether and diethyl ether was removed under reduced pressure to afford the title compound as a white solid.
1 H-NMR (CDCl 3 ) δ—values: 7.86 (dd, 1H, Ar—H), 7.56 (dd, 2H, Ar—H), 7.33-7.16 (m, 7H,Ar—H), 5.5(bs,1H),3.76(s,2H,benzylic), 2.97-2.77 (m, 5H), 2.50-2.45 (m, 2H), 1.50-1.22 (m, 13H)
IR (KBr): 1735 cm −1 , 1653 cm −1
MS: [404.8]; HPLC (99% pure).
EXAMPLE 35
Preparation of (2R)-(+)-(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetamide. L(+)-tartrate salt (Compound No. 35)
2(R)-(+)-(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetamide (Compound No. 29, 1 mmol) was dissolved in methanol (10 ml)and L(+)-tartaric acid was added and stirred at 60° C. for 1 hr. The reaction mixture was concentrated under reduced pressure, the resulting solid was triturated with diethylether and it was filtered off
m.p.: 95° C., starts decomposing
IR(KBr):1735 cm −1 ,1655 cm −1 .
HPLC:99% ee
[α] 25° C. =+10° (1.02% MeOH)
EXAMPLE 36
(2S)-(−)-(1α,5α,6α)-N-[3 -benzyl-3 -azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetamide.L(+)-tartrate salt (Compound No. 35
(2S)-(−)-(1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetamide (Compound 32, 1 mmol) was dissolved in ethanol (10 ml) and a solution of L(+)tartaric acid (1 mmol) in ethanol was added and stirred at 60° C. for 1 hr. The reaction mixture was then concentrated by evaporation of solvents under reduced pressure. Dichloromethane was added to remove last traces of ethanol and to give a solid.
m.p.: −56° C.
IR (KBr):1739 cm −1 , 1653 cm −1
EXAMPLE 37
Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2hydroxy-2-cyclobutyl-2-phenylacetamide (Compound No. 37)
Step a: Preparation of 2-hydroxy-2-cyclobutyl-2-phenyl acetic acid synthesised as per reported procedure of Saul B. Kadin and Joseph G. Cannon. J. Org. Chem., 1962, 27, 240-245.
Step b: Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclobutyl-2-phenylacetamide.
The compound of step b was prepared by following the procedure in step c of Example 1, using 2-hydroxy-2-cyclobutyl-2-phenyl acetic acid instead of 2-hydroxy-2,2-diphenyl acetic acid.
1 H NMR(CDCl 3 ) δ—values: 7.50-7.22 (m, 10H, Aromatic),6.22(s, 1H), 3.55-1.22 (m, 19H).
EXAMPLE 38
Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopropyl-2-phenylacetamide (Compound No. 38)
Step a: Preparation of 2-hydroxy-2-cyclopropyl-2-phenyl acetic acid.
Synthesised as per reported procedure of Saul B. Kadin and Joseph G. Cannon. J. Org. Chem., 1962,27,240-245.
Step b: Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopropyl-2-phenylacetamide.
The title compound was prepared by following the procedure described in step-c of Example 1, using 2-hydroxy-2-cyclopropyl phenylacetic acid instead of 2-hydroxy-2,2-diphenylacetic acid.
1 H-NMR(CDCl 3 ) δ—values: 7.63-7.23(m, 10H, aromatic), 6.11(s,1H),3.56(s,2H), 3.14-2.04(m,6H),1.59-1.25(m,10H).
EXAMPLE 39
Preparation of (1α,5α,6α)-N-[3-(3-methyl-2-butenyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)yl]-2-hydroxy-2-cyclohexyl-2-phenylacetamide (Compound No. 39)
The compound was prepared by using the procedure in Example 9, step b, using 1-bromo-3-methylbut-2-ene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran.
1 H-NMR (CDCl 3 ) δ—values: 7.66-7.02(m,5H,Aromatic),5.49(t,1H), 3.65-2.87 (m, 9H), 1.86-0.87 (m, 19H)
EXAMPLE 40
Preparation of (1α,5α,6α)-[3-(3,4-methylenedioxyphenyl)methyl-3-azabicyclo[3.1.0]hexyl-6(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetate (Compound No. 40)
Step a: Preparation of 3,4-methylenedioxy benzyl bromide.
Phosphorus tribromide (0.35 mmol) was added to a solution of 3,4-methylenedioxy benzyl alcohol (1 mmol) in 10 ml of carbon tetrachloride at room temperature. The reaction mixture was refluxed for 4 hrs., cooled to room temperature and washed with sodium carbonate solution (10 ml). The organic layer was dried and concentrated under reduced pressure to give the required product which was used as such for the next step.
Step b: (1α,5α,6α)-[3-(3,4-methylenedioxyphenyl)methyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetate.
The title compound was prepared using the procedure in Example 8, step b, using 3,4-methylenedioxy benzyl bromide instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran.
1 H-NMR (CDCl 3 ) δ—values: 7.67-6.67(m, 8H, aromatic),5.94(s,2H),4.10-3.92(dd,2H), 3.71(s,1H),3.47(s,2H),2.91-2.87(m,2H),2.30-2.27(m,3H),1.64-1.12 (m, 13H)
IR (DCM): 1720 cm −1
EXAMPLE 41
Preparation of (1α,5α,6α)-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)yl]-2-hydroxy-2-cyclopentyl-2-phenylacetate. L(+)-tartrate salt (Compound No. 41).
The compound was prepared by using the procedure in Example 34 using (1α,5α,6α)-[3-(2-(3,4-methylenedioxyphenyl)ethyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate in place of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetamide.
m.p.:88-91° C.
IR(KBr): 1725 cm −1 ,1608 cm −1 .
EXAMPLE 42
Preparation of (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2,2 diphenyl acetate. L(+)-tartrate salt (Compound No. 42)
The compound was prepared by using the method of Example 34 using (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2,2diphenyl acetate instead of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetamide.
m.p.: 53-54° C.
IR(DCM): 1730 cm −1 .
EXAMPLE 43
Preparation of (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate. L(+)-tartrate salt (Compound No. 43)
The compound was prepared by using the method of Example 34 using (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate instead of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetamide.
m.p.: 54° C.
IR(DCM): 1725 cm −1 .
EXAMPLE 44
Preparation of (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate. L(+)-tartrate salt (Compound No. 44)
The compound was prepared by using the method of Example 34 using (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate instead of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetamide.
m.p.: 55° C.
IR(DCM):1726 cm −1 .
EXAMPLE 45
Preparation of (1α,5α,6α)-N-[3-(3-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide (Compound No. 45)
This compound was prepared following the procedure as in Example 9, Step b using 3-chloromethylpyridine hydrochloride instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran.
1 H-NMR (CDCl 3 ) δ—values: 8.49-8.47 (m, 2H, aromatic); 7.62-7.21 (m, 7H, Aromatic); 6.66 (bs, 1H), 3.56 (s, 2H), 3.07-2.30 (m, 8H), 1.76-1.21 (m, 12H).
EXAMPLE 46
Preparation of (1α,5α,6α)-N-[3-(4pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenylacetamide (Compound No. 46)
This compound was prepared following the procedure as in Example 9, Step b using 4-chloromethylpyridine hydrochloride instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran.
m.pt.: 61-62° C.
1 H-NMR (CDCl 3 ) δ—values: 8.52-8.50 (m, 2H, aromatic); 7.62-7.18 (m, 7H, Aromatic); 6.71 (bs, 1H), 3.56 (s, 2H), 3.08-2.30 (m, 7H), 1.70-1.17 (m, 13H).
IR(KBr): 1658 cm −1
EXAMPLE 47
Preparation of (1α,5α,6α)-N-[3-(2-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetamide (Compound No. 47)
This compound was prepared following the procedure as in Example 10, Step b using 2-chloromethylpyridine hydrochloride instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran.
m.pt.: 62-63° C.
1 H-NMR (CDCl 3 ) δ—values: 8.52-8.50 (m, 2H, aromatic); 7.65-7.12 (m, 7H, Aromatic); 6.68 (bs, 1H), 3.73 (s, 2H), 3.00-2.36 (m, 8H), 1.76-1.16 (m, 12H).
IR (KBr): 1654 cm −1
EXAMPLE 48
Preparation of (1α,5α,6α)-N-[3-(4-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetamide (Compound No. 48)
This compound was prepared following the procedure as in Example-10, Step b using 4-chloromethyl pyridinehydrochloride instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran.
1 H-NMR (CDCl 3 ) δ—values: 8.51-8.49 (m, 2H, Aromatic), 7.63-7.18 (m, 7H, aromatic), 6.64 (bs, 1H), 3.56 (s, 2H)
EXAMPLE 49
Preparation of (1α,5α,6α)-N-[3-(3-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenylacetamide (Compound No. 49)
The compound obtained as in Example-1 was debenzylated and then N-alkylated as given below:
Step-a: Preparation of (1α,5α,6α)-N-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide:
This was synthesized using the same procedure as per Example 8, Step-a using (1α, 5α,6α)-N-3-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide instead of (1α,5α,6α)-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetate
1 H-NMR (CDCl 3 ) δ—values: 7.44-7.25 (m, 10H, Aromatic), 3.26-2.27 (m, 7H), 1.40-1.27 (m, 2H)
Step-b: To a solution of compound (1α,5α,6α)-N-[3-azabicyclo[3.1.0]-hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenylaceticamide (0.322 g, 1 mmol) in dimethyl formamide (5 ml) was added 3-chloromethylpyridine hydrochloride (0.246, 1.5 mmol) and potassium carbonate (2 mmol, 0.276 g), potassium iodide (1 mmol, 0.166 g)) and 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran (0.275 gms, 1.2 mmol). The reaction mixture was stirred at RT overnight, poured into water and extracted with ethyl acetate. The combined organic layer was washed with water, brine and dried over sodium sulphate. The crude compound obtained after evaporation of the solvent under vacuum was purified by column chromatography (silica gel 100-200 mesh) eluting the compound with 20:80 ethyl acetate:hexane.
1 H-NMR (CDCl 3 ) δ—values: 8.51-8.50 (m, 2H, aromatic), 7.64-7.25 (m, 12H, aromatic), 6.47 (bs, 1H), 3.61 (s, 2H), 3.23-3.18 (m, 2H), 2.96-2.88 (m, 2H), 2.10-2.03 (m, 2H), 1.48-1.14 (m, 3H).
IR (DCM): 1646 cm −1
EXAMPLE 50
Preparation of (1α,5α,6α)-N-[3-(4-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide (Compound No. 50)
This compound was prepared following the procedure as in Example 49, Step b using 4-chloromethyl pyridine hydrochloride instead of 3-chloromethyl pyridine hydrochloride.
1 H-NMR (CDCl 3 ) δ—values: 8.48-8.46 (m, 2H, Aromatic), 7.66-7.18 (m, 12H, Aromatic), 6.52 (bs, 1H), 3.57 (s, 2H), 3.20-3.16 (m, 2H), 2.96-2.93 (m, 2H), 2.35-2.30 (m, 2H), 1.60-1.25 (m, 3H).
IR (KBr): 1658 cm −1
EXAMPLE 51
Preparation of (1α,5α,6α)-N-[3-(2-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide (Compound No. 51)
A solution of (1α,5α,6α)-N-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenylacetamide (0.322 g, 1 mmol), 2-pyridine carboxaldehyde (0.256 g, 2.4 mmol), sodium triacetoxy borohydride (0.678 g, 3.2 mmol) and acetic acid (0.228 g, 3.8 mmols) in tetrahydrofuran (25 ml) was stirred for 4 days. The reaction mixture was poured into saturated sodium bicarbonate solution and extracted with ethyl acetate. The organic layer was washed with water, dried over sodium sulphate and concentrated under reduced pressure. The residue was purified by column chromatography (100×200 mesh, size silicagel) using 80:20 ethyl acetate:dichloromethane.
1 H-NMR (CDCl 3 ) δ—values: 8.53-8.52 (m, 1H, Aromatic), 7.67-7.14 (m, 13H, Aromatic), 6.39 (bs, 1H), 3.74 (s, 2H), 3.20-3.16 (m, 2H), 3.01-2.98 (m, 2H), 2.15-2.02 (m, 3H), 1.33-1.19 (m, 2H)
IR(KBr): 1658 cm −1
EXAMPLE 52
Preparation of (1α,5α,6α)-N-[3-(2-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No. 52)
This compound was synthesized following the procedure of Example 51 using (1α,5α,6α)-N-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide instead of (1α,5α,6α)-N-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide.
1 H-NMR (CDCl 3 ) δ—values: 8.52 (m, 1H, Aromatic), 7.67-7.16 (m, 8H, Aromatic), 6.47 (bs, 1H), 3.74 (s, 2H), 3.08-2.02 (m, 9H), 1.66-0.88 (m, 10H)
IR (KBr): 1644 cm −1
EXAMPLE 53
Preparation of (1α,5α,6α)-N-[3-(3-pyridylmethyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No. 53)
This compound was synthesized using the procedure of Example 10, Step b but using 3-chloromethylpyridine hydrochloride instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b) benzofuran.
1 H-NMR (CDCl 3 ) δ—values: 8.53-8.51 (m, 2H, Aromatic), 7.63-7.18 (m, 7H, Aromatic), 6.5 (bs, 1H), 3.57 (s, 2H), 3.12-3.91 (m, 6H), 2.33-2.31 (m, 2H), 1.40-1.17 (m, 10H)
IR (KBr): 1642 cm −1
EXAMPLE 54
Preparation of (1α,5α,6α)-N-[3-(3-methyl-2-butenyl)-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide (Compound No. 54)
This compound was synthesized by following the procedure of Example 10, Step b but using 1-bromo-3-methyl-but-2-ene instead of 5-(2-bromoethyl)-2,3-dihydrobenzo[2,3-b]benzofuran.
1 H-NMR (CDCl 3 ) δ—values: 7.61-7.26 (m, 5H, Aromatic), 6.43 (bs, 1H), 5.20 (t, 1H), 3.07-2.98 (m, 7H), 2.33-2.30 (m, 2H), 1.76-0.92 (m, 17H)
EXAMPLE 55
Preparation of (1α,5α,6α)-N-[3-(3,4-methylenedioxyphenyl)methyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenylacetamide (Compound No. 55)
This compound was synthesized by following the procedure of Example 51 but using 3,4-methylenedioxybenzaldehyde instead of 2-pyridine carboxaldehyde, and (1α,5α,6α)-N-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenyl acetamide instead of (1α,5α,6α)-N-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenylacetamide.
m.p.: 148-150° C.
1 H-NMR (CDCl 3 ) δ—values: 7.61-6.66 (m, 8H, Aromatic), 6.42 (bs, 1H), 5.93 (s, 2H), 3.46 (s, 2H), 3.19-2.88 (m, 6H), 2.29-2.27 (m, 2H), 1.71-1.22 (m, 11H)
IR (KBr): 1652 cm −1
EXAMPLE 56
Preparation of (1α,5α,6α)-N-[3-(3,4-methylenedioxyphenyl)methyl-3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetamide (Compound No. 56)
This compound was synthesized by following the procedure of Example 51 but using (1α,5α,6α)-N-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenylacetamide instead of (1α,5α,6α)-N-[3-azabicyclo[3.1.0]hexyl-6-(aminomethyl)-yl]-2-hydroxy-2,2-diphenylacetamide and 3,4-methylenedioxybenzaldehyde instead of 2-pyridine carboxaldehyde.
m.p.: 130-133° C.
1 H-NMR (CDCl 3 ) δ—values: 7.61-6.68 (m, 8H) 5.93 (s, 2H), 3.45 (s, 2H), 2.92-2.84 (m, 5H), 2.28-2.26 (m, 2H), 1.34-1.17 (m, 13H)
IR (KBr): 1651 cm −1
EXAMPLE 57
Preparation of (1α,5α,6α)-[3-(4-methyl-3-pentenyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate. L(+) tartrate salt (Compound No. 57)
This compound was synthesized by following the procedure of Example 34 but using (1α,5α,6α)-[3-(4-methyl-3-pentenyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate instead of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide.
m.p.: 87-89° C.
HPLC: 94.6%
EXAMPLE 58
Preparation of (1α,5α,6α)-[3-(2-3,4-methylenedioxyphenyl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate. L(+) tartrate salt (Compound No. 58)
This compound was synthesized by following the procedure of Example 34 but using (1α,5α,6α)-[3-(2-(3,4-methylenedioxyphenyl)ethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclohexyl-2-phenyl acetate instead of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide.
m.p.: 76° C. (starts decomposing)
HPLC: 97.48%
EXAMPLE 59
Preparation of (1α,5α,6α)-[3-(1-phenylethyl)-3-azabicyclo[3.1.0]hexyl-6-(methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate. L(+) tartrate salt (Compound No. 59)
This compound was synthesized following the procedure of Example 34 but using (1α,5α,6α)-[3-(1-phenylethyl)-3-azabicyclo[3.1.0]hexyl-6-methyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetate instead of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]hexyl-6(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide.
m.p.: 78° C. (starts decomposing)
HPLC:94.2%
EXAMPLE-60
Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]-hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide hydrochloride salt (Compound No. 60)
This compound was synthesized by the following procedure:
Ethereal hydrochloric acid (10 ml) was added to a solution of compound 3 (1 mmol) in ethanol (5 ml). The reaction mixture was stirred at room temperature and then concentrated under reduced pressure.
HPLC:96.39%
EXAMPLE 61
Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]-hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide. L(−) malic acid salt (Compound No. 61)
This compound was synthesised by following the procedure of Example 34 but using L(−) malic acid instead of L-(+) tartaric acid
HPLC:98.28%
EXAMPLE 62
Preparation of (1α,5α,6α)-N-[3-benzyl-3-azabicyclo[3.1.0]-hexyl-6-(aminomethyl)-yl]-2-hydroxy-2-cyclopentyl-2-phenyl acetamide. Maleate salt (Compound No. 62)
This compound was synthesized by following the procedure of Example 34 but using malic acid instead of L-(+) tartaric acid
HPLC:98.37%
Biological Activity
Radioligand Binding Assays:
The affinity of test compounds for M 2 and M 3 muscarinic receptor subtypes was determined by [ 3 H]-N-methylscopolamine binding studies using rat heart and submandibular gland respectively as described by Moriya et al., (Life Sci, 1999, 64 (25):2351-2358) with minor modifications.
Membrane preparation: Submandibular glands and heart were isolated and placed in ice cold homogenising buffer (HEPES 20 mM, 10 mM EDTA, pH 7.4) immediately after sacrifice. The tissues were homogenised in 10 volumes of homogenising buffer and the homogenate was filtered through two layers of wet gauze and filtrate was centrifuged at 500 g for 10 min. The supernatant was subsequently centriged at 40,000 g for 20 min. The pellet thus obtained was resuspended in same volume of assay buffer (HEPES 20 mM, EDTA 5 mM, pH 7.4) and were stored at −70° C. until the time of assay.
Ligand binding assay: The compounds were dissolved and diluted in DMSO. The membrane homogenates (150-250 μg protein) were incubated in 250 μl of assay buffer (HEPES 20 mM, pH 7.4) at 24-25° C. for 3 h. Non-specific binding was determined in the presence of 1 μM atropine . The incubation was terminated by vacuum filtration over GF/B fiber filters(Wallac). The filters were then washed with ice cold 50 mM Tris HCl buffer (pH 7.4). The filter mats were dried and bound radioactivity retained on filters was counted. The IC 50 & Kd were estimated by using the non-linear curve fitting program using G Pad Prism software. The value of inhibition constant Ki was calculated from competitive binding studies by using Cheng & Prusoff equation ( Biochem Pharmacol , 1973, 22: 3099-3108), Ki=IC 50 /(1+L/Kd), where L is the concentration of [ 3 H]NMS used in the particular experiment.
Functional Experiments using Isolated Rat Bladder:
Methodology:
Animals were euthanized by overdose of urethane and whole bladder was isolated and removed rapidly and placed in ice cold Tyrode buffer with the following composition (mMol/L) NaCl 137; KCl 2.7; CaCl 2 1.8; MgCl 2 0.1; NaHCO 3 11.9; NaH 2 PO 4 0.4; Glucose 5.55 and continuously gassed with 95% O 2 and 5% CO 2 .
The bladder was cut into longitudinal strips (3 mm wide and 5-6 mm long) and mounted in 10 ml organ baths at 30° C., with one end connected to the base of the tissue holder and the other end connected to a polygraph through a force displacement transducer. Each tissue was maintained at a constant basal tension of 2 g and allowed to equilibrate for 1 hour during which the PSS was changed every 15 min. At the end of equilibration period the stabilization of the tissue contractile response was assessed with 1 μmol/L of Carbachol consecutively for 2-3 times. Subsequently a cumulative concentration response curve to carbachol (10 −9 mol/L to 3×10 −5 mol/L) was obtained. After several washes, once the baseline was achieved, cumulative concentration response curve was obtained in presence of NCE (NCE added 20 min. prior to the second CRC).
The contractile results were expressed as % of control E max. ED50 values were calculated by fitting a non-linear regression curve (Graph Pad Prism). pKB values were calculated by the formula pKB=−log[(molar concentration of antagonist/(dose ratio−1))]
where,
dose ratio=ED50 in the presence of antagonist/ED50 in the absence of antagonist.
In Vivo Experiments Using Anaesthetized Rabbit
Methodology
Male rabbits were anaesthetized with urethane 1.5 g/kg intravenously. Trachea was cannulated to maintain the patency of airway. Femoral vein and femoral arteries of both sides were cannulated for the administration of vehicle or drug substances for the measurement of BP and administration of carbachol intra-arterially respectively.
Polyethylene tubing was introduced into the bladder through the urethra and tied at the neck of the bladder. The other end of the catheter was connected to the Grass polygraph through a Statham pressure transducer. The bladder was filled with warm (37° C.) saline. Both the ureters were ligated and cut proximally to drain the urine coming from kidneys. A stabilization period of 30-60 was allowed for stabilization of parameters from surgical procedures.
Salivary response was assessed by measuring the weight of a preweighted cotton gauze kept for 2 minutes in the buccal cavity immediately after the carbachol challenge.
At the end of stabilization period 2 control responses to carbachol (1.5 μg/kg intra-arterial) on bladder pressure and salivation were obtained and this response was considered as 100%. Subsequently, the effect of increasing dose of NCE (ranging from 3 μg/kg to 1 mg/kg) or vehicle (i.v., 15 min before carbachol challenge) was examined.
The change in bladder pressure and salivation were expressed as % change from pretreatment control averages. The ID 50 values for salivation and bladder pressure inhibition were calculated using Graph Pad Prism software, by fitting the values at dose into non-linear regression curve. Oxybutynin and Tolterodine were used as standards for comparison.
The bladder selectivity to salivation was calculated by using following formula and expressed as fold of selectivity of oxybutinin in the same model.
ID
50
Salivary
response
ID
50
Bladder
pressure
The results of the in-vitro and in-vivo tests are listed in Tables II and III.
In-Vitro Tests
TABLE II Receptor Binding Assay Functional M 2 M 3 Selectivity Assay pKi pKi M 2 /M 3 pK B Compound No. 1 6.59 7.6 10 8.14 Compound No. 2 6.85 8.25 25 8.7 Compound No. 3 7.02 8.23 16 8.6 Compound No. 4 8.6 9.41 6 8.79 Compound No. 5 8.4 8.91 3 7.4 Compound No. 6 8.46 9.25 6 8.5 Compound No. 7 7.9 8.23 2 7.88 Compound No. 8 7.87 8.05 15 Compound No. 9 6.59 7.41 6.6 6.77 Compound No. 10 6.47 7.49 10.47 7.87 Compound No. 11 8.03 8.62 3.89 8.40 Compound No. 12 7.64 8.38 5.49 8.42 Compound No. 13 6.48 7.28 6.3 7.21 Compound No. 14 5.7 6.72 10.5 Compound No. 15 6.59 7.87 19 7.81 Compound No. 16 6.75 7.63 7.6 7.94 Compound No. 17 8.36 9.1 5.5 8.09 Compound No. 18 8.4 9.15 5.6 7.4 Compound No. 19 8.15 8.8 4.5 7.99 Compound No. 20 7.9 8.73 6.8 7.1 Compound No. 21 6.59 7.82 17 7.5 Compound No. 22 7.06 8.23 14.8 7.65 Compound No. 23 6.23 6.8 3.7 Compound No. 24 6.56 7.51 8.9 7.54 Compound No. 25 6.37 7.6 17 7.9 Compound No. 26 9.52 9.5 0.95 7.94 Compound No. 27 9.65 9.85 1.6 8.27 Compound No. 28 7.85 8.4 3.5 8.5 Compound No. 29 7.91 8.96 11.2 9.15 Compound No. 30 9.13 9.46 2 8.79 Compound No. 31 9.15 9.75 3.98 8.37 Compound No. 32 6.2 7.65 28 7.8 Compound No. 33 7.39 8.4 10.23 Compound No. 34 7.22 8.23 8 8.8 Compound No. 35 7.35 8.46 13 9.21 Compound No. 36 6.21 7.65 7.8 Compound No. 37 7.24 8.23 8 Compound No. 38 6.37 7.19 6.6 Compound No. 39 7.79 8.36 3.7 Compound No. 40 9.08 9.36 1.9 Compound No. 41 8.1 8.23 1.25 8.35 Compound No. 42 8.63 9.3 4.64 8.46 Compound No. 43 8.15 8.46 2.02 7.7 Compound No. 44 8.63 9.16 3.7 7.81 Compound No. 45 <6 6.63 Compound No. 46 <6 7.17 Compound No. 47 6.15 7.42 Compound No. 48 <6 7.14 Compound No. 49 <6 7.16 Compound No. 50 <6 6.94 Compound No. 57 8.46 9.34 7.5 Compound No. 58 7.82 8.3 7.55 Compound No. 60 7.31 8.28 8.38 Compound No. 61 7.36 8.29 8.66 Compound No. 62 7.28 8.17 8.94 Tolterodine 8.4 8.3 0.98 9.05 Oxybutynin 8.3 9.2 7.34 8.93 Atropine 9 9.6 0.83 9.96
In-Vivo Tests
TABLE III
IC 50 Bladder
IC 50 Salivary
Fold
Fold of
Compound
Pressure
Response
Selectivity
Oxybutynin
Oxybutynin
36.6 ± 12
21.6 + 5
0.58 + 0
1.0
Tolterodine
26.9 + 4
35.1 + 9
1.76 + 0
2.31
Compound
20.13 + 2
15.41 + 1
0.80 + 0
1.38
No. 42
Compound
53.81 + 2
85.06 + 28
1.94 + 0
3.34
No. 43
Compound
23.25 + 6
18.62 + 4
1.09 + 0
1.88
No. 44
Compound
15.84
31.62
—
3.45
No. 35
Compound
398.1
501.2
—
2.17
No. 36
While the present invention has been described in terms of its specific embodiments, certain modifications and equivalents will be apparent to those skilled in the art and are intended to be included within the scope of the present invention.
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This invention generally relates to the derivatives of novel 3,6 disubstituted azabicyclo[3.1.0]hexanes. The compounds of this invention are muscarinic receptor antagonists which are useful, inter-alia for the treatment of various diseases of the respiratory, urinary and gastrointestinal systems mediated through muscarinic receptors. The invention also relates to pharmaceutical compositions containing the compounds of the present invention and the methods of treating the diseases mediated through muscarinic receptors.
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FIELD OF THE INVENTION
This invention relates generally to the field of compact circuit assemblies and packaging and, more particularly, to a packaged circuit for direct attachment to a wall plate duplex receptacle as a male plug having lateral dimensions within the receptacle periphery.
BACKGROUND OF THE INVENTION
Most electronic circuits which are designed to be directly powered by 110 V AC circuit outlets are packaged within a rectangular module connected to the outlet receptacle with either a cord extending from the module or a plug arrangement integral with the module having blades extending therefrom for connection to the 110 VAC receptacle with the module extending substantially over the entire wall plate or encroaching on the second receptacle in a duplex receptacle wall plate. Power supplies for portable computers and chargers for cellular phones and battery packs are exemplary of this type of device. While circuit improvements have reduced the size of these modules, the footprint required for direct plug arrangements is still greater than the dimension of standard duplex receptacles. This results in the ability to only use one of the receptacles in a duplex outlet or using only a two blade plug arrangement without ground pin to allow inverting the module when plugged into a top receptacle to allow use of the lower receptacle. This type of arrangement typically still encroaches on the adjacent receptacle in a four receptacle faceplate arrangement.
It is therefore desirable to have circuit module packaging and associated circuits which provide a footprint within the dimensions of a standard receptacle to allow full use of a duplex outlet while providing the ability to use a ground pin for full circuit ground implementation, where required, and plug stability provided by the additional structure of the ground pin.
SUMMARY OF THE INVENTION
A circuit assembly and package according to the present invention incorporates a front cover with power contacting blades extending from a front surface thereof for electrical engagement in a receptacle having a standard peripheral dimension. A housing is attached to the front cover and extends perpendicularly therefrom. The housing contains an electrical circuit connected to the power contacting blades which is contained on a plurality of circuit boards mounted substantially perpendicular to the front cover. The housing and front cover create a footprint less than the peripheral dimension of the receptacle. A connecting cable extends from the housing distal the front plate and is connected to the electrical circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features and advantages of the present invention will be better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
FIG. 1 is a front view of a National Electrical Manufacturers Association (NEMA) face place for a duplex receptacle;
FIG. 2 is an isometric view of a circuit assembly and packaging according to the present invention;
FIG. 3 a is a side view of the circuit assembly and packaging of the embodiment of FIG. 2 with the tapered housing removed;
FIG. 3 b is a top view of the circuit assembly and packaging of the embodiment of FIG. 2 with the tapered housing removed;
FIG. 4 is an isometric view of the tapered housing;
FIG. 5 a is a front view of the circuit assembly and packaging of the embodiment of FIG. 2 with the front cover and associated blades and ground pin removed;
FIG. 5 b is a front view as in FIG. 4 a with the socket and header board interconnection removed to show cable attachment;
FIG. 6 a is an isometric view of the front cover with the connection blades and ground pin;
FIG. 6 b is a side view of the front cover with the connection blades and ground pin;
FIG. 7 is a side view of the connection blade configuration;
FIG. 8 a is a top view of an exemplary circuit board for use in an embodiment of the invention;
FIG. 8 b is a side view of the circuit board of FIG. 9 a;
FIG. 9 a is a pictorial view of two circuit assembly and packaging units according to the present invention plugged into a standard duplex receptacle;
FIG. 9 b is a rear view of the two circuit assembly and packaging units of FIG. 9 plugged into a standard duplex receptacle;
FIG. 10 is a block diagram of an exemplary 6 volt 500 milliamp charging circuit for use in an embodiment of the present invention;
FIGS. 11 a and 11 b are a circuit schematic of the exemplary 6 volt 500 milliamp charging circuit of FIG. 10 .
DETAILED DESCRIPTION OF THE INVENTION
Referring to the drawings, FIG. 1 shows a standard National Electrical Manufacturers Association (NEMA) duplex device front cover with associated dimensions. This front cover is defined by the NEMA 5-15R wallplate receptacle dimensions which accepts male plug features conforming to NEMA 5-15P. This duplex receptacle arrangement is prevalent in the majority of homes and workplaces in the United States. The wallplate 10 incorporates two receptacles 12 each having a general dimension of a 1.343 inch diameter circle truncated on the top and bottom by horizontal chords spaced at 1.125 inches from the center.
FIG. 2 shows an embodiment of a circuit assembly and packaging unit according to the present invention. The unit includes body 14 having a front cover 16 with power connection blades 18 and a ground pin 20 extending from a front surface 22 . A tapered housing 24 engages and extends from the front cover opposite the blades and houses the circuit elements of the unit. The peripheral dimensions of the front surface and housing are approximately 0.010″ less than the NEMA duplex receptacle periphery as defined by the aperture in the NEMA standard duplex receptacle wallplate drawing in FIG. 1 for the embodiment shown. The tapered housing terminates in a cylindrical extension 26 which engages a strain relief 28 for connection to cord 30 . A charger plug 32 having a standard male DC connector 34 is attached to the connection cord. The DC connector shown in the current embodiment is compatible with most Nokia® phones, but other DC connectors may be used for compatibility with other manufacturer's phones.
Details of the internal arrangement of the unit for the exemplary embodiment are shown in FIGS. 3 a and 3 b . For this embodiment, the circuit assembly is contained on two circuit boards, an upper circuit board 36 and lower circuit board 38 . The power connection blades 18 incorporate a vertical arm 40 which engages and supports the circuit boards at a first end. Two posts 42 support the circuit boards at a second end opposite the front cover. For the embodiment shown herein, posts 42 are connected by a web 43 (as also shown in FIG. 5 b ) having an aperture for transition of the conductors of the connection cord. The strain relief for the connection cord has a slightly tapered ferule 44 extending into a tail 46 which is integrally molded into the sheathing of the connection cord for structural integrity. Interconnection between the circuit boards is accomplished by a header 48 depending from the upper board which is received in a socket 49 mounted to the opposing surface of the lower board. The header and socket provide additional structural support and rigidity between the primary structural support attachments at the board ends. By adding additional sockets to the upper circuit board 36 a third circuit board with associated headers may be mounted above upper circuit board 36 . By adding additional sockets to lower circuit board 38 , a fourth circuit board with associated headers may be mounted below lower circuit board 38 .
The tapered housing containing the electrical circuits, as shown in FIG. 4 , has a truncated circular cross section footprint to fit within the NEMA wallplate aperture dimensions. Two sets of parallel ribs 50 extend from the inner circumference of the housing on each side to provide channels receiving the lateral edges of the circuit boards as best seen in FIGS. 5 a and 5 b . For the embodiment shown, the housing is molded using a two slide mold with a lateral slide extending through corner cutouts 52 to form engaging tangs 54 on attachment ears 56 . The length of the housing accommodates the circuit boards and then tapers to the cylindrical extension 26 which incorporates a slightly tapered bore 58 to frictionally engage the ferule of the strain relief on the connection cord. Conductors 60 for the connection cord extend from the strain relief ferrule and are connected to circuit output terminals 62 . The strain relief incorporates stepped cylindrical extensions from the ferrule for engagement with the web 43 and associated aperture of rear support posts 42
Front cover 16 , as best seen in FIGS. 6 a and 6 b , houses the blades and ground pin for connection to the 110 VAC outlet receptacle. Ears 64 are formed in the front plate for engagement with the corner cutouts in the housing. Notches 66 receive the attachment ears of the housing with the tang of each ear captured by webs 68 extending across bases of the notches. A central aperture 70 and four vent apertures 72 are present in the front cover to allow filling of the completed circuit assembly and packaging unit with an epoxy encapsulant, as will be described in greater detail subsequently. Two tabs 74 extend from a rear surface 76 of the front cover for positioning engagement on the internal circumference 78 in the periphery of the housing. Additionally, tabs 74 provide a protrusion for engagement with encapsulating material filling the housing, as will be described in greater detail subsequently.
The geometry of power connection blades 18 is shown in detail in FIG. 7 . Vertical arms 40 on the blades terminate at both ends in rectangular posts 80 which engage the circuit boards. As shown in FIGS. 8 a and 8 b , the circuit boards each have forward circular engagement holes 82 which receive the rectangular posts in an interference fit. Similarly, rear engagement holes 84 receive posts 42 to maintain separation at the rear of the boards. While the embodiment shown herein employs two horizontally spaced boards, three or more boards are stacked in alternative embodiments for more complex circuits. For the embodiment shown herein, the boards have chamfered rear corners for clearance from the tapered rear of the housing.
The efficacy of a circuit assembly and package according to the present invention is demonstrated in FIGS. 9 a and 9 b . Two units of the embodiment of the invention disclosed herein are plugged into the two receptacles of a single duplex face plate 10 . The body 14 of each unit extends from the receptacle to which it is plugged into without interference with the second receptacle. It is unnecessary to invert the unit when plugged into a top receptacle for spacing from the bottom receptacle thereby allowing use of a ground pin both for additional structural support of the unit and electrical connection when required by the circuit assembly.
An exemplary circuit for use with the present invention is shown in block diagram form in FIG. 10 . The circuit comprises a 6 volt DC 500 mA charger for devices such as a cell phone or Personal Digital Assistant (PDA). 110V AC is connected to a power entry circuit 102 which supplies a start-up regulator 104 and a 5 VDC power supply 106 . Startup regulator 104 provides a limited amount of current at 15VDC to the integrated circuits controlling both the 5VDC power supply 106 , and the 5VDC–6VDC DC/DC converter 108 . The output current of startup regulator 104 in the present embodiment is limited to about 10mA typically. A 5VDC to 6VDC DC/DC converter and isolation circuit 108 is powered by the 5VDC power supply and provides the desired charging current output. The start-up regulator provides DC biasing supply currents for both the 5VDC power supply circuit 106 and the converter and isolation circuit 108 which both operate from DC voltages and require an initial DC voltage supply to initiate operation.
A schematic of the components contained in the circuits described in FIG. 10 is shown in FIGS. 11 a and 11 b . While described herein with respect to 110 VAC power, the circuit embodiment disclosed herein provides universal voltage input compliance (110VAC, 60 Hz/220VAC, 50 Hz). Power from the 110 VAC receptacle is received on pins P 1 A and P 1 B of the power entry circuit 102 and is series connected through fuse FS 1 to provide a failsafe mechanism for disconnecting the 110VAC input in the case of either an internal short circuit or an output short circuit. For clarity in the drawings, P 1 A and P 1 B are shown as + and − respectively, however those skilled in the art will recognize in standard AC wiring circuits these comprise power, or hot, and neutral. The power entry circuit also contains a parallel connected transient protection diode TPD 1 which protects the internal electronic devices against line surge voltages and plug/unplug transient voltages. The output of power entry circuit 102 supplies AC power to a start-up regulator 104 and a 5 VDC power supply 106 . Startup regulator 104 provides a limited amount of current at 15VDC to the integrated circuits controlling both the 5VDC power supply 106 , and the 5VDC–6VDC DC/DC converter 108 . In the present embodiment, the startup regulator 104 comprises a first diode bridge rectifier DB 1 , a bank of high voltage capacitors C 1 a –C 1 g , and a regulation circuit, for the embodiment herein an LR8 integrated circuit from Supertex, Inc., which regulates the 110VAC rectified and filtered raw DC output down to 15VDC linearly. Feedback resistors R 1 and R 2 set the output DC voltage level and output capacitors C 2 , C 2 a provide additional filtering and leveling of the DC startup supply voltage, Vin. The output current of startup regulator 104 in the present embodiment is limited to about 10 mA typically.
AC power from the power entry circuit 102 is also provided to a second diode bridge DB 2 in the 5 VDC power supply. Output from the second bridge is filtered with capacitor bank C 3 a–c and provided to a power FET U 3 . FET U 3 is switched by a FET driver output signal, (OUT) from Pulse Width Modulation (PWM) controller circuit U 2 which is powered by “Vin” from the regulator.
The PWM control circuit governs the amount of power delivered to output inductor L 3 and the load by varying the duty cycle of a constant frequency square wave applied to the gate, or control input of power FET switch U 3 . Resistor R 5 connected to the “RT” input of PWM control circuit U 2 sets the frequency of this internal oscillator, in this case at approximately 1MHz. When power FET U 3 is switched “ON”, by driver output “OUT” from PWM controller circuit U 2 , inductor L 1 is energized and conducts current which is then accumulated on capacitor bank C 8 a–d and C 20 – 32 . As the voltage on the capacitor bank charges towards 5VDC, resistors R 7 and R 6 provide a feedback signal to PWM circuit U 2 . The voltage divider comprised of R 7 and R 6 reduces the nominal 5VDC to 1.25VDC which is compared against the internal 1.25VDC reference in the PWM controller IC. With the power FET in the “ON” condition the voltage at the 5VDC supply output will begin to go above 5VDC. When this occurs, the feedback resistive divider comprised of R 7 and R 6 will cause the input at the voltage feedback input (Vfb) of PWM circuit U 2 to exceed 1.25VDC, thus causing the internal comparator to switch and drive the gate input of power FET U 3 “LOW” so that it will switch into the “OFF” condition, and thereby foreshortening the pulse width of the positive half of the output square wave (therefore, “Pulse Width Modulation”). During the period the power FET U 3 is “OFF”, the energy stored in inductor L 3 by virtue of its current conduction is discharged and supplied to the load and to charge the output capacitor bank through Schottky rectifier U 4 .
When the load on the 5VDC output causes the voltage to drop as it discharges the output capacitor bank, the process is reversed, with the voltage feedback input “Vfb” being driven below 1.25VDC, and the internal comparator switching to a “HIGH” state and driver output “OUT” switching to a “HIGH” state, causing power FET U 3 to turn “ON” and repeating the cycle. In this manner the operation continues, adjusting and adapting to the varying load conditions by varying the amount of time FET U 3 is turned “ON” during each cycle of the PWM control circuit U 2 's oscillator. The duty cycle of the PWM controller can typically vary up to 85% to provide maximum power to the load.
A soft-start capability is provided by capacitor C 4 connected to the “SS” input of PWM circuit U 2 in conjunction with internal circuitry to reduce the level of inrush current on a plugging event. Resistors R 3 and R 4 divide the “Vin” input to be compared against the under voltage lockout threshold internal to the PWM circuit U 2 at input “UVL”. If the voltage at “Vin” drops too low to provide proper operation of U 2 , this mechanism will trigger the UV Lockout provision and shut down the circuit, providing a failsafe condition. Resistor RIO is connected in series with the DC return path to the diode bridge, DB 2 to provide an overcurrent sense mechanism. If the voltage across RIO indicates an overcurrent condition in the load, an internal comparator connected to the “CS”input will trigger and shut down the output drive “OUT” until proper conditions are reestablished. This overcurrent sense voltage is coupled back to the PWM controller “CS” input via resistor R 9 and capacitor C 9 , which provide a time delay and filtering so the “CS” input does not respond to noise or transient voltages.
Compensation for duty cycles in excess of 50% is achieved by modifying the signal at the voltage feedback input “Vfb” through a network comprised of C 6 , C 7 , and R 8 connected between the “COMP” and “Vfb” inputs of the PWM controller U 2 . The startup regulator circuit 104 supplies DC power to the PWM controller circuit through the “Vcc” input. A DC return path for the PWM IC is established by the connection of the PWM controller “GND” input to the common negative voltage reference point at the terminal of diode bridge DB 2 . The 5VDC supply circuit 106 as described herein is an example of a “Buck” or “stepdown” switching regulator.
The 6 VDC converter and isolation circuit receives the 5VDC power from the 5VDC power supply at pin 3 of the primary winding of transformer TRI. Use of the transformer provides a basic insulation isolation from the 110VAC line voltage to any point accessible to the end user. Basic insulation isolation is necessary to comply with Underwriters Laboratory requirements for consumer safety. PWM controller IC U 5 and power switching FET U 6 act in much the same manner as described above for the 5VDC supply circuit 106 , with noted exceptions. Notably, the use of a 1:1.5 step-up transformer TRI allows the output voltage of the secondary winding at pin 7 of TRI to be greater than the input voltage, and therefore as high as 7.5VDC given a 5VDC input voltage. Additionally, the positioning of the transformer primary winding between the input DC supply and the drain of power switching FET U 6 , makes the FET a “Low Side” switch, simplifying the gate drive requirements, and requiring the use of a “catch” diode SD 1 connected across the primary winding to reduce the potential for a possibly damaging high voltage transient at the drain of FET U 6 when it is switched from “ON” to “OFF”. Catch diode SD 1 also provides a conduction path for the energy stored in the primary winding inductance to provide power to the load through the magnetically coupled secondary winding when power FET switch U 6 is turned “OFF” by a “LOW” from the PWM circuit “OUT” output.
Output rectifier diode SD 2 is connected to the secondary winding to rectify the output signal, and capacitor bank C 19 a–j filters and levels the 6VDC output. One other point of note is the method of feedback to PWM controller IC U 6 .
In order not to lose the approximately 1500V isolation achieved by the use of transformer TR 1 , an optocoupler OP 1 is used to feedback an appropriate control signal to the PWM control IC U 5 voltage feedback input “Vfb”. Resistors R 20 and R 21 divide the nominal 6VDC output voltage to 3VDC at the inverting (−) input to voltage comparator U 7 . The non-inverting (+) input to voltage comparator U 7 is connected to a 3VDC bandgap reference biased from the nominal 6VDC output through resistor R 22 . Thus, if the output rises above 6VDC, the comparator (−) input will be above 3VDC, and the voltage comparator output at pin 7 will be driven to a “LOW” state, removing the drive current from the Light Emitting Diode (LED) between pins 1 and 3 of optocoupler OP 1 . With no optical signal present at the base of the phototransistor between pins 6 and 4 of optocoupler OP 1 , the output at pin 6 will be in a high impedance state, and thus will be driven to 2.5VDC by the resisitive voltage divider (⅙) combination formed by R 16 and R 14 and the 15VDC startup supply output, “Vin”. Since the internal reference is at 1.25VDC, the output drive from PWM control circuit U 6 “OUT” will be driven “LOW” and the power switching FET U 6 turned “OFF”, thus providing negative feedback and maintaining excellent isolation.
When the nominal 6VDC output sinks below 6VDC, the (−) input to voltage comparator U 7 sinks below 3VDC, and the output of voltage comparator U 7 transitions to a high impedance state, and is pulled “HIGH” towards 6VDC through pullup resistor R 19 . The actual voltage will be determined by the forward current (˜2mA) through the LED between pins 1 and 3 of optocoupler OP 1 . With the now substantial optical power incident on the phototransistor base, and the high gain of the phototransistor between pins 6 and 4 at the second side of optocoupler OP 1 , the voltage at the optocoupler output pin 6 is quickly driven to the saturation voltage of the phototransistor (<0.4VDC). This will cause the output of PWM control circuit U 5 “OUT” to be driven “HIGH”, thus turning power switch FET U 6 “ON”, reenergizing the primary winding of transformer TR 1 , and repeating the cycle anew as the nominal 6VDC voltage output is driven higher. Capacitor C 14 and resistor combination R 14 and R 16 behave as an integrating circuit, delaying both the rising voltage and falling voltage at the voltage feedback input “Vfb” of PWM control IC U 5 , and therefore consideration must be given to compensate the feedback loop appropriately via the “COMP” input to PWM IC U 5
Besides the noted exceptions, the remainder of the PWM IC operates as described previously and will not be repeated here. This DC/DC converter topology is commonly referred to as a “Boost” or “Flyback” converter. Values for exemplary components of the circuits and various feedback control components for the circuits described above and shown in FIGS. 11 a and 11 b are provided in table 1. The design has been effected in such a manner as to allow interfacing with both the US standard 110VAC and many of the international 220VAC power mains. Suitable passive plug adaptors may be used to effect the mating to a number of different international plug receptacle standards.
TABLE 1
Component
Value
Part no./Type
R10, R18
0.33
Ohm
ERJ-3RQFR33V
R9, R14, R17
1
K
ERJ-3EKF1001V
R2
1.82
K
ERJ-3EKF1821V
R3, R11, R19
2
K
ERJ-3EKF2001V
R6
3.01
K
MCR03EZPFX3011
R16, R20, R21, R22
4.99
K
MCR03EZPFX4991
R5
6.19
K
ERJ-3EKF6191V
R7
9.09
K
MCR03EZPFX9091
R4, R8, R12, R15
15
K
ERJ-3EKF1502V
R1, R13
20
K
ERJ-3EKF2002V
C6, C15
220
pF
ECJ-1VC1H221J
C7, C16
3.3
nF
C1608C0G1H332J
C4, C12
0.01
uF
ECJ-1VB1E103K
C2, C5, C9, C11, C13, C14,
0.1
uF
MCH182CN104KK
C17, C18, C33
C1a–C1g, C3a–C3c
0.56
uF
501S49W564KV6E
C2a, C8a–C8d, C19a–C19j,
22
uF
C3225X5R1E226K
C26–C32
C20–C25
220
uF
ECEV1AA221XP
L1
68
uH
MSS1260-683MX
TR1
Transformer
PA1032
DB1, DB2
Diode Bridge 400 V
HD04
0.8 A
U1
450 V Linear Reg.
LR8N8
10 mA
U2, U5
100 V PWM Con-
LM5020MM-1
troller
U3, U6
N-Ch Pwr MOSFET
STD1NB60
600 V 1 A
DPAK
U4
Fast Recovery
SMBY01-400
Rectifier 400 V 1 A
U7
Voltage Comparator
LM311M
U8
Voltage Reference
LM4040EIM3X-3.0
3.0 V SOT-23
SD1, SD2
Schottky Diode
ZHCS2000
40 V 2 A SOT23-6
OP1
Optocoupler
TLP181
FS1
FUSE 1025TD
1025TD250mA
250VAC 250 mA
TPD1
Trans. Voltage Pro-
P4SMA350CA
cessor 350 V,
400 W
P3
2 mm 5-pin
2063-01-01-P2
Receptacle
P4
2 mm 5-pin Header
2163-01-01-P2
Straight
For the embodiment described herein, a simplified method of manufacture on the unit is created by the form of the packaging components. Power blades 18 and ground pin 20 are integrally molded into front cover 16 . Assembly of the circuits on circuit boards 36 and 38 is accomplished by conventional pick and place and soldering methods. The connecting cable strain relief is engaged to web 43 interconnecting support posts 42 with the stepped cylindrical extension inserted through the aperture in the web. The conductors of the connecting cable are connected to associated lower board terminals. The two circuit boards are then mounted to pins 80 on the vertical arms of the power blades with front mounting holes 82 , as previously described, and then soldered for electrical connection. Coincident with mounting to the vertical arms, the socket and header on the boards are mated and posts 42 are inserted in the rear mounting holes on the boards and soldered for structural support and rigidity at the rear of the multi-board assembly.
The connecting cable is threaded through the tapered bore in the cylindrical extension of the housing. The tapered ferule 44 of the strain relief engages the tapered bore to preclude pull through of the cable assembly and to provide a liquid tight seal. The printed circuit boards are inserted into the channels formed by ribs 50 and sliding engage the channels while the cable is drawn through the bore. The housing is snap fit onto the front cover employing attachment ears 56 which are received by the notches 66 in the front cover with the tangs 54 on the ears then constrained by the webs 68 in the notches. Ears 64 on the front cover are closely received in corner cutouts 52 in the housing.
Upon completion of mechanical assembly, the unit is positioned vertically with the front cover at the top. A high thermal conductivity encapsulating compound is then injected through central aperture 70 , using a syringe or comparable injection tool, with venting through apertures 72 providing encapsulation of the circuit boards and connections for additional structural rigidity of the entire unit as well as shock protection and thermal conduction for the circuit elements on the circuit boards. Tabs 74 on the front cover are engaged by the encapsulating material to provide additional structural connection to the housing.
Having now described the invention in detail as required by the patent statutes, those skilled in the art will recognize modifications and substitutions to the specific embodiments disclosed herein. Such modifications are within the scope and intent of the present invention as defined in the following claims.
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A circuit assembly and package incorporates a front cover with power contacting blades extending from a front surface thereof for electrical engagement in a receptacle having a standard peripheral dimension. A housing is attached to the front cover and extends perpendicularly therefrom. The housing contains an electrical circuit connected to the power contacting blades which is contained on a plurality of circuit boards mounted substantially perpendicular to the front cover. The housing and front cover create a footprint less than the peripheral dimension of the receptacle. A connecting cable extends from the housing and is connected to the electrical circuit.
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RELATED APPLICATIONS
[0001] The present invention is a continuation-in-part of the patent application Ser. No. 11/117,053, filed on Nov. 15, 2007, entitled “Method of Producing a Reflective Design on a Substrate and Apparatus”.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0002] Not Applicable
THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT
[0003] Not Applicable
REFERENCE TO A SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING
[0004] Not Applicable
BACKGROUND OF THE INVENTION
[0005] Garments for running, cycling, footwear, hats, backpacks, jackets, pet collars, and leashes all utilize photo-reflective material for the purpose of increasing the wearer's visibility and safety after dark. This material is typically attached to the garment by sewing or is adhered using heat activated adhesive. One problem with the addition of reflective material is that it typically reduces the aesthetics of the garment in daylight. As a result, many consumers are unwilling to take advantage of the beneficial features provided by reflective materials on garments.
[0006] Thus there exists a need for more visually appealing garments that have light reflecting material.
BRIEF SUMMARY OF INVENTION
[0007] A method of producing a reflective design that overcomes these and other problems includes the steps of lasering a pattern on an adhesive side of a reflective laminate material. The reflective laminate material is applied to a substrate. A carrier layer of the reflective laminate is removed to reveal a reflective design on the substrate. This method allows for highly customized reflective designs at a reasonable cost that are very visually appealing. The substrate may be a textile, paper, or suitable decal material. The substrate may be a garment or may be a patch that is sewn onto a garment or applied to the garment with an adhesive, or a decal that can be applied to an object with a smooth surface.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0008] FIG. 1 is a block diagram of a system for producing a reflective design on a textile in accordance with one embodiment of the invention;
[0009] FIG. 2 is an example of a reflective design on a textile in accordance with one embodiment of the invention;
[0010] FIG. 3 is a flow chart of the steps used in producing a reflective design on a textile in accordance with one embodiment of the invention;
[0011] FIG. 4 is a cross sectional view of a reflective laminate in accordance with one embodiment of the invention;
[0012] FIG. 5 is a flow chart of the steps used in producing a reflective design in accordance with one embodiment of the invention; and
[0013] FIG. 6 is a flow chart of the steps used in producing a reflective design in accordance with one embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0014] The present invention increases the aesthetic appeal of garments that have a reflective film. In one embodiment, the reflective film is patterned on its surface with a laser. In another embodiment, the adhesive on the backside of the reflective film is patterned with a laser, causing portions of the reflective film to not adhere to the substrate. Once laminated, the lasered film creates a reflective pattern. The pattern can be text or graphics.
[0015] FIG. 1 is a block diagram of a system 10 for producing a reflective design on a textile in accordance with one embodiment of the invention. A reflective film 12 is laminated or sewn to a substrate 14 . In one embodiment, the substrate 14 is a textile product. A pattern or design is put into a computer 16 . The computer 16 directs a laser 18 and associated optics to focus the laser beam 20 onto a surface 22 of the reflective film 12 . It is thought that the laser beam partially ablates and partially carbonizes the surface of the reflective material. The reflective film 12 has tiny glass beads reflectors embedded in a polymer. Where the surface is carbonized the surface looks black and the glass beads are no longer able to enhance the reflection of light. Note that the appearance of the finished product is substantially increased by only having the surface of the reflective film patterned by the laser. To achieve adequate results, the laser intensity and dwell on a particular spot need to be precisely set or the laser may not sufficiently mark the reflective film or it may burn through the reflective film. Ideally, the surface is patterned so lightly that to a user's touch the laser patterned area appears to be at essentially the same level as the rest of the front surface of the reflective film. Note that the pattern may be made by a number of dots where the laser has been focused on the surface of the reflective material. The density of the dots can be used to create shades of grey. On a colored reflective film, variations in dot density results in duotones.
[0016] In one embodiment, the laser beam is positioned at different spots on a stationary reflective film. Conversely, it is possible to move the reflective film and have the laser beam be stationary.
[0017] FIG. 2 is an example of a reflective design on a textile in accordance with one embodiment of the invention. A textile 30 has a reflective film 32 laminated to the textile 30 . Commonly, heat activated adhesive is used to laminate the reflective film 32 to the textile 30 . The reflective film 32 may be laminated by sonic welding, RF welding or any other of the well known laminating techniques. A design 34 is fashioned by a laser onto the surface of the reflective film 32 . The appearance of the overall product can be enhanced by selecting a textile 30 that has smooth surface commonly associated with a higher thread count and thinner yarn. For some applications like collars, it is helpful if the webbing of the textile is braided at approximately 45 degrees to the length of the collar. When this is done, bending the collar does not result in bumps from the textile in the reflective film. Before the reflective film 32 is laminated to the textile 30 the textile may be subjected to heat and pressure. This further tightens the weave of polymer based textiles. As a result, the reflective film sits flat on the textile rather than having a bumpy looking surface. In one embodiment, the reflective film is treated with an ink before it is patterned with the laser. The ink may be an alcohol based ink.
[0018] FIG. 3 is a flow chart of the steps used in producing a reflective design on a textile in accordance with one embodiment of the invention. The process starts, at step 100 . A high thread count, thin yarn textile at step 102 . In one embodiment, the textile is a polymer based textile. In another embodiment, the textile is a polymer based textile, but not nylon. Pressure and heat are applied to a surface of the textile at step 104 . In one embodiment, only heat is applied to the surface of the textile. The reflective film is laminated to the textile at step 106 . The graphics and text design is input into a computer at step 108 . An ink may be applied to the reflective film at step 110 . At step 112 , the laser is focused onto the reflective film with the appropriate power and dwell settings to create the design, which ends the process at step 114 .
[0019] FIG. 4 is a cross sectional view of a reflective laminate 120 in accordance with one embodiment of the invention. The reflective laminate 120 has a carrier layer 122 , which protects the reflective film 124 . An adhesive 126 , commonly heat and/or pressure activated, is on an underside of the reflective film 124 . An adhesive protection layer 128 protects the adhesive 126 and keeps if from accidentally becoming adhered to the wrong surface.
[0020] In order to create a pattern in the adhesive laminate 120 , the adhesive protection layer 128 is removed. A laser, such as laser 18 in FIG. 1 , then creates a pattern in the adhesive. By appropriately adjusting the output settings of the laser the adhesive is ablated at selected locations. Next, the reflective laminate 120 with the patterned adhesive is applied to a substrate, such as substrate 14 in FIG. 1 . Application may include the use of heat or pressure or both to cause the patterned reflective laminate to adhere to the substrate. The carrier layer 122 is then removed. When the carrier layer 122 is removed areas of the reflective film 124 that had adhesive ablated by the laser are also removed. As a result, a pattern of the reflective film 124 and the substrate is formed. Note that because the pattern is created on the adhesive backside of the reflective film 124 , the image has to be a mirror image of the desired end result. In one embodiment, the top side 22 ( FIG. 1 ) of the reflective film 124 is also patterned with the laser, as discussed with respect to FIGS. 1-3 . Commonly the substrate will be a textile. The textile may be a finished garment, a garment panel, or the textile may form a patch. The patch may be sewn onto a garment or may have an adhesive backing to form an iron-on patch. Alternatively, the substrate can be paper or a material used to form a decal. Note that the laser is utilized to ablate the adhesive so as used in this embodiment lasering means a process that vaporizes or neutralizes the adhesive.
[0021] FIG. 5 is a flow chart of the steps used in producing a reflective design in accordance with one embodiment of the invention. The process starts, step 130 , by lasering a pattern on an adhesive side of a reflective laminate material at step 132 . The reflective laminate material is applied to a substrate at step 134 . At step 136 the carrier layer of the reflective laminate, as well as the non-adhered laminate material is removed, which ends the process at step 138 .
[0022] FIG. 6 is a flow chart of the steps used in producing a reflective design in accordance with one embodiment of the invention. The process starts step 140 , by creating a design in a reflective film at step 142 . At step 144 the reflective film is applied to a substrate, which ends at step 146 . In one embodiment, steps 142 and 144 are reversed. Note that the substrate may be a textile, paper or a suitable decal material such as polyester film. The textile may be a garment or a patch. The patch may be sewn onto a garment or may be an iron-on patch. For an iron-on patch, the back side of the patch is a heat or pressure or combination adhesive. Commonly the laser patterned reflective film is attached to the patch textile by a heat and/or pressure adhesive. It is possible to attach the reflective film by applying heat or pressure by using a non-stick guard to protect the adhesive backside of the patch. Thus even if the adhesive on the patch is melted it is contained by the non-stick guard, such as a sheet of Teflon. Once cooled, the patch easily peels off the Teflon with the adhesive intact. The patch can later be heat applied to a garment. Alternatively, by adjusting temperature, pressure, and/or dwell time, it is possible to adhere the reflective film to the patch without activating the adhesive on the backside of the patch.
[0023] In one embodiment, the patch is made with tabs that wrap around an article and adhere to each other, thus improving adhesion of a patch to articles such as pet collars
[0024] Thus there has been described a system and method for producing a reflective design on a substrate that results in more visually appealing garments that have light reflecting material.
[0025] While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alterations, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alterations, modifications, and variations in the appended claims.
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A method of producing a reflective design includes the steps of lasering a pattern on an adhesive side of a reflective laminated material. The lasering ablates the adhesive and causes these areas to not adhere. The reflective laminate material is applied to a substrate. A carrier layer of the reflective laminate is removed to produce a reflective design on the substrate. This method allows for highly customized designs at a reasonable cost that are very visually appealing. The substrate may be a textile, paper, or decal material. The textile may be the garment or may be a patch that is sewn onto a garment or applied to the garment with an adhesive.
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This is a Continuation of application Ser. No. 08/015,850 filed Feb. 10, 1993, now abandoned.
BACKGROUND OF THE INVENTION
The present invention relates to a genomic DNA fragment of the bacterium Streptococcus pneumoniae, a probe capable of specifically hybridizing with the genomic DNA of Streptococcus pneumoniae, a primer for specifically amplifying the genomic DNA of Streptococcus pneumoniae, a reagent and a method for selectively detecting, in a biological sample, said bacterium, used with the probe of the invention.
Research studies have been carried out on the isolation of two nucleotide fragments, on their sequencing, their specificity towards the genomic DNA of Streptococcus pneumoniae and their use for the production of hybridization probes intended for a diagnostic method.
These two fragments are respectively the hexB gene, deposited and accessible at the gene library of EMBL (European Molecular Biology Laboratory, Heidelberg, Germany) under the number M29686 and the study of which was especially the subject of the publication by M. PRUDHOMME, B. MARTIN, V. MEJEAN and J. P. CLAVERYS (1989) J. Bacteriol. 171, 5332-5338 and which encodes an essential protein of the system for the mismatch repair of the Streptococcus pneumoniae DNA, and the ami operon, deposited and accessible at the gene library of EMBL under the number X17337 and the study of which has especially been the subject of the publication by G. ALLOING, M. C. TROMBE and J. P. CLAVERYS (1990 Mol. Microbiol., 4, 633-644, and which is involved in the transport of oligopeptides in pneumococcus.
For each of these two fragments, various sub-fragments were prepared and used as hybridization probes for the genomic DNA of Streptococcus pneumoniae. The most commonly used probes are, in the case of the hexB gene, the hexB-S7 fragment obtained by the action of the restriction enzymes HindIII-BglIII (from nucleotide 1321 to nucleotide 1776) containing 455 nucleotides, and, in the case of the ami operon, the ami-S2 fragment obtained by the action of the restriction enzymes BamHI-EcoRI (from nucleotide 2419 to nucleotide 3564), containing 1145 nucleotides.
Each of these two probes was subjected to hybridization experiments according to the so-called "dot-blot" technique according to MANIATIS et al. (1982), Molecular Cloning, Cold Spring Harbor, with the genomic DNA of Streptococcus pneumoniae and the genomic DNA of other genera and species of bacteria, under stringent conditions (50% formamide, at 420° C.) , on nylon membranes (trade name Biodyne A, from the company Pall), using two concentrations of respectively 10 ng and 100 ng of genomic DNA.
Identical results were obtained with the two probes hexB-S7 and ami-S2. FIG. 1 shows the results obtained with the probe ami-S2 previously labeled by radioactive labeling with 32 P (trade name Kit Multiprime from the company Amersham), the hybridizations being visualized by autoradiography, for 12 hours at -70° C. According to FIG. 1, two DNA spots of respectively 10 ng (dotted arrow) and 100 ng (solid arrow) were prepared for each of the bacterial strains used. The bacterial strains were grouped together by series and numbered within each series as follows:
a series:
a1-a11: Clinical isolates of Streptococcus pneumoniae belonging to different serotypes.
b series:
b1-b5: Streptococcus oralis of the API collection (BioMerieux SA) (internal references API No. 7902025, 7902072, 8305023, 8040010, accessible at National Culture Type Collection under the reference NCTC11427, 8408077).
b6-b10: Clinical isolates classified Streptococcus sanguis based on API-20 Strep tests (BioMerieux SA) of which the result is indicated in brackets below in the order, SI (4061440), SII (0260451), SII (0270441), SI (0061440), SII (0240440).
b11-b12: Clinical isolates classified Streptococcus mitis based on the API-20 Strep tests (0040401 for both strains).
b13-b14: Clinical isolates classified Streptococcus milleri based on the API-20 Strep tests (1061010 for both strains).
b15-b16: Clinical isolates classified Streptococcus salivarius based on the API-20 Strep tests (5060451 and 5060461).
b17-b20: Clinical isolates of Enterococcus faecalis, Listeria monocytogenes, Haemophilus influenzae and Neisseria meningitidis.
c series:
c: "Atypical streptococci" obtained from clinical isolates.
According to FIG. 1, the results are as follows:
All the strains of Streptococcus pneumoniae of the a) series give very visible signals which are proportional to the concentration considered.
The atypical streptococci of the c, c91, C120, C108, C108, C92, C188, C139, C155, C184, C115, C65 and C174 series give the same signals as those of the a) series and could therefore be classified, based on this test, in the Streptococcus pneumoniae species.
All the strains of Streptococus oralis of the b) series, with the exception of the b5 strain, the strain Streptococcus mitis b11 and the atypical streptococci of the c, C185, C160 and c85 series, give a visible signal for the concentration of 100 ng, the intensity of the signal being about 10 times weaker than that obtained for Streptococcus pneumoniae at the same concentration.
These results therefore demonstrate the lack of specificity respectively of the probes hexB-S7 and ami-S2 for Streptococcus pneumoniae, within the genus Streptococcus since a partial, but nevertheless significant, hybridization is detected with the species Streptococcus oralis, the closest species to Streptococcus pneumoniae and Streptococcus mitis. These probes are therefore unsatisfactory for the production of a selective test for detecting Streptococcus pneumoniae among other bacterial species which are most closely related.
In conformity with the publication by A. FENOLL, J. V. MARTINEZ-SUAREZ, R. MUNOZ, J. CASAL and J. L. GARCIA, Eur. J. Clin. Microbiol. Infect. Dis., 9 (June 1990) 396-401, other research studies led to the preparation of a hybridization probe (pCE3) for the genomic DNA of Streptococcus pneumoniae which is a 650-base pair fragment isolated from the lyt A gene, the latter encoding the N-terminal end of the streptococcal autolysin, amidase.
This probe was tested on 44 streptococcal strains among which 27 were identified as atypical streptococci strains and the other 17 as strains of Streptococcus viridans, based on conventional identification tests.
Although this probe provides a solution to the problem of the identification of Streptococcus pneumoniae, and in particular among atypical streptococci, it has, nevertheless, two disadvantages:
the probe used is a 650-base pair fragment and its production industrially is therefore not easy,
and, in particular, the specificity of this probe is entirely linked to the presence of the lyt A gene, of which the copy in the genomic DNA of Streptococcus pneumoniae is unique; therefore, it will not be able to detect or identify a strain of S. pneumoniae from which the lyt A gene has been deleted; furthermore, this small number of copies is a disadvantage for the detection by direct hybridization and for the amplification of the target DNA.
SUMMARY OF THE INVENTION
The present invention aims to solve the above-mentioned problems of selective detection of Streptococcus pneumoniae, especially those encountered in medical bacteriology.
The first subject of the invention is a single-stranded fragment of the genomic DNA of Streptococcus pneumoniae comprising at least one nucleotide sequence having at least 70% homology with at least one nucleotide sequence chosen from the nucleotide sequences SEQ ID NO 2, SEQ ID NO 3, SEQ ID NO 4, which are represented at the end of the description, and their respective complementary sequences. Complementary sequence is understood to mean any sequence which completely hybridizes with the sequence represented. Fragment is understood to mean a piece of DNA which is detached, isolated or broken off from genomic DNA.
Preferably, the nucleotide sequence of the fragment according to the invention has at least 85% homology with at least one of said nucleotide sequences.
The single stranded fragment can consist essentially of at least one nucleotide sequence which is at least 70% homologous and preferably at least 85% homologous to at least one or to one nucleotide sequence selected from the group consisting of the nucleotide sequences SEQ ID NO 2, SEQ ID NO 3, SEQ ID NO 4 and their respective complementary sequences.
A second subject of the invention directly uses said fragment and consists of a probe which is capable of specifically hybridizing with the genomic DNA of Streptococcus pneumoniae, said probe comprising a nucleotide sequence having at least 70% homology with at least a portion of a consensus sequence of the genomic DNA of Streptococcus pneumoniae, this consensus sequence being chosen from the nucleotide sequences SEQ ID NO 2, SEQ ID NO 3, SEQ ID NO 4 and their respective complementary sequences.
Preferably, the nucleotide sequence of the probe of the invention has at least 85% homology with at least a portion of said consensus sequence.
The probe of the invention advantageously comprises at least 12 nucleotides.
Preferably, the probe of the invention comprises the nucleotide sequence SEQ ID NO 3.
When it comprises SEQ ID NO 3, it may be flanked at its 5' end by the nucleotide sequence SEQ ID NO 2 and/or at its 3' end by the nucleotide sequence SEQ ID NO 4.
The nucleotide sequence SEQ ID NO 3 may be repeated, and it is, advantageously four times contiguously.
According to the invention, a probe may have a shorter nucleotide sequence and be chosen from the sequences SEQ ID NO 5, SEQ ID NO 6 and SEQ ID NO 7, which are presented at the end of the description.
The labeling of the probe does not influence its specificity with respect to the genomic DNA of Streptococcus pneumoniae and an appropriate marker is preferably chosen from radioactive isotopes, from enzymes chosen from peroxidase and alkaline phosphatase and those capable of hydrolyzing a chromogenic, fluorigenic or luminescent substrate, from chromophoric chemical compounds, from chromogenic, fluorigenic or luminescent compounds, from nucleotide base analogs and from biotin.
In order to use a probe of the invention in vivo, its molecular structure is chemically modified. Appropriate chemical modifications, which make it possible to increase the stability to enzymatic degradation, especially due to nucleases, and additionally to increase the hybridization yield, do not of course affect the sequence of bases. Examples thereof are the introduction, between at least two nucleotides, of a group chosen from diphosphate esters, from alkyl- and aryl-phosphonate and from phosphorothioate, or the replacement of at least one deoxyribose by a polyamide.
A third subject of the invention is a primer for the specific polymerization of the genomic DNA of Streptococcus pneumoniae so as to obtain an amplification of the latter. This primer comprises a nucleotide sequence having at least 70% homology with at least a portion of a consensus sequence of the genomic DNA of Streptococcus pneumoniae, this consensus sequence being chosen from the nucleotide sequences SEQ ID NO 2, SEQ ID NO 3, SEQ ID NO 4 and their respective complementary sequences.
Preferably, the nucleotide sequence of a primer of the invention is chosen from the sequences SEQ ID NO 8 to SEQ ID NO 21, which are represented at the end of the description.
Depending on the amplification techniques considered, it is preferable to use a pair of primers comprising at least one primer of the invention.
In the case where the pair consists of two primers of the invention, said pair is advantageously chosen from the pairs of primer consisting of a primer of the nucleotide sequence SEQ ID NO 8 and a primer of any one of the nucleotide sequences SEQ ID NO 11, SEQ ID NO 13, SEQ ID NO 15, SEQ ID NO 17, SEQ ID NO 19 and SEQ ID NO 21, and from the pairs of primer consisting of a primer of the nucleotide sequence SEQ ID NO 10 and a primer of any one of the nucleotide sequences SEQ ID NO 13, SEQ ID NO 15, SEQ ID NO 19 and SEQ ID NO 21.
A fourth subject of the invention is a reagent for selectively detecting Streptococcus pneumoniae in a biological sample, using a probe of the invention as described above.
If the hybridization technique considered is the so-called sandwich technique, the reagent of the invention comprises a capture probe and a detection probe having the characteristics of a probe of the invention, the detection probe being especially labeled by means of one of the markers described above. Capture probe refers to any polynucleotide fixed upon a macromolecular support, capable of hybridizing with a portion (or capture region) of a nucleic acid to be detected in a sample (target), in particular DNA. The capture probe may be a natural nucleic acid fragment (in particular DNA), a natural or synthetic oligonucleotide or a synthetic nucleic acid fragment (in particular DNA) which is unmodified or containing one or more modified bases such as inosine, 5-methyldeoxycytidine, deoxyuridine, 5-dimethylaminodeoxyuridine, 2,6-diaminopurine, 5-bromodeoxyuridine or any other modified base which allows the hybridization.
Appropriate chemical modifications which make it possible to increase the stability to enzyme degradation and enhance the hybridisation yield may also be envisaged, such as for example the introduction, between at least two nucleotides, of a group chosen from diphosphate, alkyl- or acylphosphonate and phosphorothioate esters, or the replacement of at least one deoxyribose by a polyamide. The detection probe is a probe capable of hybridising with a portion of the target (detection region) which corresponds to the definition above and is labeled by means of any appropriate marker chosen from enzymatic markers, preferably from horseradish peroxydase, alkaline phosphotase or any enzyme capable of hydrolysing a chromogenic, fluorigenic or luminiscent substrate; radioactive isotopes, chromophoric chemical compounds; chromogenic, fluorigenic or luminiscent compounds, or anologs of nucleotide bases and biotin. In the reagent, the probe of the invention is in liquid medium or is directly or indirectly fixed on a solid support. Said support is in any appropriate form such as a tube, cone, well, microtiter plate, sheet, or soluble polymer. It consists of a natural or synthetic material, modified chemically or otherwise, and is, depending on the technique adopted, chosen from polystyrenes, styrene/butadiene copolymers, styrene/butadiene copolymers mixed with polystyrenes, polypropylenes, polycarbonates, polystyrene/acrylonitrile copolymers, styrene-methyl methacrylate copolymers, from synthetic nylon and natural fibers, from polysaccharides and cellulose derivatives.
Furthermore, the reagent of the invention may contain at least one primer as described above, so as to allow an amplification technique to be performed before the selective detection of Streptococcus pneumoniae and it preferably contains a pair of primers according to the invention.
The final subject of the present invention is a method for the selective detection of Streptococcus pneumoniae in a biological sample, consisting in exposing the genomic DNA of the bacteria contained in said sample, in the form of single-stranded fragments, to a probe of the invention, and then in detecting the regions of hybridization with said probe.
Most known hybridization techniques can be used in this method, and especially the so-called dot-blot, Southern and sandwich hybridization techniques. To carry out the latter technique, the method consists in previously exposing the genomic DNA of the bacteria in the sample to a capture probe of the invention, upon which the genomic DNA of the Streptococcus pneumoniae will bind specifically, and then in exposing the bound DNA to a detection probe of the invention.
According to the invention, the method advantageously comprises a stage for the amplification of the genomic DNA of Streptococcus pneumoniae, in the presence of an appropriate enzymatic system and at least one primer and especially a pair of primers of the invention, prior to the stage for the detection of Streptococcus pneumoniae.
The development of the invention and its usefulness are now set out according to stages 1 to 4 and in support of FIGS. 2 and 3:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows results obtained with the probe ami-S2, labeled by radioactive 32 P.
FIG. 2, makes it possible to locate, in the vicinity of the various Streptococcus pneumoniae genes, the repetitive nucleotide sequences called boxA, boxB and boxC respectively. FIG. 2 shows the organization of the BOX sequences and their positions relative to identified flanking genes or open reading frames and their transcriptional signals. BoxA, boxB and boxC are indicated by black-, open- and shaded- rectangles, respectively. Each copy of boxB at the same locus is numbered below the line for identification in FIG. 3. SI and SII indicate leftside and rightside BOX elements in the aspS fragment, respectively. Coding regions and their direction of transcription are denoted by open rectangles with an arrow. Vertical bars with an open circle denote a rho-independent terminator having a stem-loop structure that blocks transcription. The lytA promoter is indicated by a vertical bar with an open square. Base pair distances between the coding regions, elements and transcription initiation and termination signals are indicated above each line.
FIG. 3 illustrates the determination of the consensus sequences SEQ ID NO 2, SEQ ID NO 3 and SEQ ID NO 4 respectively, by alignment of the various repetitive sequences in the vicinity of 5 Streptococcus pneumoniae genes.
DESCRIPTION OF PREFERRED EMBODIMENTS
STAGE 1--Isolation of a repetitive sequence in the genomic DNA of Streptococcus pneumoniae
The isolation, using genetic recombination techniques in vitro during extensive work on the study of Streptococcus pneumoniae, of a genomic DNA sequence made it possible to identify, by means of the technique of hybridization with total DNA according to the SOUTHERN technique, a fragment exhibiting homology with several other genomic fragments. This situation results in the generation of 20 to 25 fragments. This fragment was found, experimentally, to be specific for Streptococcus pneumoniae. The determination of its sequence made it possible to identify a new gene designated mmsA which may be involved in the molecular mechanisms of DNA repair and recombination.
A specific sequence responsible for these multiple hybridizations was localized in this fragment. It is a nucleotide sequence situated in the region downstream, in the 5'→3' direction, of the mmsA gene. This sequence, which is obtained by the action of the restriction enzymes Hpal and PvuII, has 340 base pairs, according to the SEQ ID NO 1 given at the end of the description. The complete nucleotide sequence of the two complementary strands of this fragment was determined by the chain termination method (according to SANGER et al., Proc. Natl. Acad. Sci. USA, 1977, 74, 5463-5467) using single-stranded DNA templates of the phage M13. The existence, inside this sequence, of a 45-nucleotide sequence called boxB, directly repeated 4 times, was thus demonstrated.
This boxB sequence was subsequently also found, by sequence comparison, in regions upstream of the hexB, comA, lytA, ply, SI, SII genes. It was observed that these copies of boxB could be flanked in 5' and in 3' by sequences containing about fifty nucleotides, which are also conserved, and are called boxA and boxC respectively. A consensus sequence was determined for each of these boxes, A, B and C respectively, by alignment of the different nucleotide sequences of the hexB, comA, lytA, ply, SI and SII regions, which corresponds to the nucleotide chain most frequently found in these regions. The consensus sequences SEQ ID NO 2, SEQ ID NO 3 and SEQ ID NO 4 correspond to the boxes, A, B and C respectively.
Organization and chromosomal location:
The general organization of these repetitive regions in the genomic DNA of Streptococcus pneumoniae is schematically represented in FIG. 2.
The chromosome sites containing the sequences situated in the vicinity of the hexB, comA, lytA and mmsA genes have been characterized. These sites are located at different points on the chromosome map of Streptococcus pneumoniae established by separation of DNA fragments by pulse field electrophoresis (Gasc et al., 1991). Adopting a circular representation for this map, based on an arbitrary division into 60 minutes, with a 0/60 position situated at the top of the circle, and a clockwise direction, the location, expressed in minutes, of various fragments is, for the test strain:
comA: 7'
hexB: 10-11'
lytA: 21-24'
mmsA: 24-26'
This observation suggests that fragments containing these repetitive regions have completely different chromosomal locations.
This situation is very advantageous since it ensures that, even in the event of a substantial chromosome rearrangement, many copies of this repetitive sequence are conserved in the genomic DNA.
STAGE 2--Development of the probes of the invention
Sequence alignments between the various copies identified were performed by computer processing. These alignments made it possible to obtain the consensus sequences described above for the copies of boxA, boxB and boxC. These consensus sequences are given at the end of the description by the references SEQ ID NO 2, SEQ ID NO 3 and SEQ ID NO 4 respectively.
According to FIG. 3, these alignments made it possible to define the sequence and location of three oligodeoxyribonucleotides indicated at the end of the description by the references SEQ ID NO 5, SEQ ID NO 6 and SEQ ID NO 7 respectively. One of these oligonucleotides is derived from the alignment of the copies of boxA (SEQ ID NO 5). The second oligodeoxyribonucleotide (SEQ ID NO 6) is derived from the alignment of the copies of boxB, a third (SEQ ID NO 7) is derived from the alignment of the copies of boxC. These oligodeoxyribonucleotides, as well as any other consensus sequence established from the data for boxA, boxB and boxC, or any other sequence exhibiting at least 70% homology with one of the consensus sequences, can be used as specific probe for the genomic DNA of Streptococcus pneumoniae.
STAGE 3--Determination of specificity by molecular hybridization using the probes SEQ ID NO 6 and SEQ ID NO 7
a) Choice of the bacterial strains:
The classification of the bacterial strains used is specified below:
1--Laboratory strain R800 of Streptococcus pneumoniae (Lefevre, J. C., Claverys, J. P., and Sicard, A. M. (1979) J. Bacteriol. 138, 80-86), derived from the strain R36A (Tiraby, G., Fox, M. S., and Bernheimer, H. (1975) J. Bacteriol. 121, 608-618).
2--Atypical clinical isolate (101/87), lacking a capsule, resistant to optochin, resistant to lysis by DOC, but lytA + .
3--Strain GM99 of Escherichia coli (Prere, M.-F. and Fayet, O. (1986) Microbiol. Lett. 33, 37-41).
4--Clinical isolate classified Streptococcus sanguis II (API-20 Strep 0260451), resistant to optochin, pneumolysin negative.
5--Clinical isolate classified Streptococcus sanguis II (API-20 Strep 0270441), average resistance to optochin, pneumolysin negative.
6--Strain OB11 of Streptococcus gordonii (ex Streptococcus sanguis Challis (Haisman, R. J. and Jenkinson, H. F. 1991. Mutants of Streptococcus gordonii Challis overproducing glucosyltransferase. J. Gen. Microbiol. 137, 483-489), biovar 2 according to Kilian et al. (Kilian et al., 1989).
7--Clinical isolate classified Streptococcus mitis (API-20 Strep 0040401).
8--Clinical isolate classified Streptococcus mitis (API-20 Strep 0040401).
9--Strain of Streptococcus oralis, API SYSTEM collection (ref. No. 7902072).
10--Strain NCTC 11427 of Streptococcus oralis (Ronda et al., 1988).
11--Clinical isolate of Streptococcus pneumoniae (serotype 18).
12--Clinical isolate of Streptococcus pneumoniae (serotype 6).
13--Clinical isolate of Streptococcus pneumoniae (serotype 23).
Among the streptococcal species, the results of DNA-DNA hybridization (Kilpper-Balz, R., Wenzig, P., and Schleifer, K. H. 1985. Molecular relationships and classification of some viridans streptococci as Streptococcus oralis and amended description of Streptococcus oralis (Bridge and Sneath 1982) Int. J. Sys. Bact. 35, 482-488) show that Streptococcus oralis, which comprises various strains previously classified as S. sanguis II, S. mitior, S. viridans, and S. mitis are the two species most closely related to Streptococcus pneumoniae. The NCTC 11427 strain of Streptococcus oralis selected for this study is the typical strain (Kilpper-Balz et al., 1985, and Coykendall, A. L. 1989, Classification and identification of Viridans Streptococci. Clin. Microbiol. Rev. 2, 315-328, Kilian, M., Mikkelsen, L., and Henrichsen, H. 1989, Taxonomic study of Viridans Streptococci: description of Streptococcus gordonii sp. nov. and amended descriptions of Streptococcus sanguis (White and Niven 1946), Streptococcus oralis (Bridge and Sneath 1982); and Streptococcus mitis (Andrewes and Horder, 1906), Int. J. Sys. Bact. 39, 471-484). It was in fact from this strain that the DNA fragment which constitutes a specific probe for Streptococcus oralis was isolated (Schmidhuber et. al., 1988). Streptococcus mitis is represented by two clinical isolates.
Streptococcus gordonii, a newly created species (Kilian et. al., 1989) which includes many strains previously classified as S. sanguis II, represented by the strain OB11 (ex S. sanguis Challis) (Kilian et. al., 1989, Haisman and Jenkinson, 1991), as well as S. sanguis, which is not represented in this study, can be considered, based on the results of DNA-DNA hybridization, as less closely related to Streptococcus pneumoniae than Streptococcus oralis and Streptococcus mitis.
The results of the DNA-DNA hybridization experiments are demonstrated in Kilpper-Balz et. al. (1985), in which is represented at least one typical strain of each of these species.
b) Preparation of the samples, gel electrophoresis and transfer onto nylon membrane:
Chromosomal DNA of the various streptococcal strains was prepared by the technique described by Fenoll et. al. (1990). The enzymatic digestion by the enzyme PstI as well as the agarose gel electrophoresis and the transfers onto charged nylon membrane (Biodyne B, from PALL) were carried out under the conditions described by Maniatis, T., Fristsch, E. F., and Sambrook (1982), Molecular cloning; A laboratory manual (Cold Spring Harbor, N.Y.: Cold Spring Harbor Laboratory).
c) Molecular hybridization conditions:
The oligodeoxyribonucleotide was labeled in 5' by T4 bacteriophage DNA kinase (from Bethesda Research Laboratory) using γ- 32 p!ATP (at 3000 Ci/mM). 50 μl of solution of labeled oligonucleotide (1×10 7 cpm for about 2.5 picomoles) were introduced into a hybridization buffer 6× SSC (saline sodium citrate), 10× Denhardt's, 0.1 SDS (Na dodecyl sulfate)!, (50 mg/ml salmon sperm DNA, 1% of Boehringer blocking reagent) (Maniatis et. al., 1982). The hybridization was performed at 40° C. (probe SEQ ID NO 6) or 48° C. (probe SEQ ID NO 7), for about 15 hours. After two brief washes in a solution of 6× SSC, 0.1% SDS, at room temperature, the membrane was placed in contact with an X-ray film which had been exposed for 3 to 36 hours at -70° C.
An experiment for the identification of Streptococcus pneumoniae by molecular hybridization was performed using, as probe, the oligonucleotides (SEQ ID NO 6 and SEQ ID NO 7). Chromosomal DNAs from Streptococcus pneumoniae and other streptococci, including Streptococcus oralis and Streptococcus gordonii, two of the species most closely related to this bacterium, were digested with the restriction enzyme PstI, separated by agarose gel electrophoresis and then transferred onto nylon membrane. The 32 P-labeled oligonucleotide was placed in contact with this membrane, under standard hybridization conditions.
The hybridization results show very strong hybridization signals obtained with the DNA of Streptococcus pneumoniae, whereas they are nonexistent with the DNA of Streptococcus oralis, the species most closely related to Streptococcus pneumoniae, as well as with the DNA of Streptococcus gordonii, of clinical isolates classified as Streptococcus sanguis, and of one of the clinical isolates classified as Streptococcus mitis.
STAGE 4--Identification of Streptococcus pneumoniae by direct colony hybridization using a nonradioactive and semi-automated detection system described in French Patent No. 90 07249 whose content is incorporated into the present description, where appropriate.
The identification of the Streptococcus pneumoniae strains from the strains described in stage 3 was confirmed based on this nonradioactive detection technology.
The extraction of total DNA from colonies was carried out in the following manner. A bacterial colony standardized as a 10 9 bacteria inoculum is taken up in 400 μl of a 0.1M solution of sodium citrate containing 0.85 g of sodium chloride. 40 μl of sodium deoxycholate detergent (1%) are added. After incubating for 5 minutes at room temperature, 4 phenol-chloroform extractions are carried out (Maniatis et. al., 1982). The DNA is precipitated with ethanol. The pellet is taken up in 100 μl of sodium citrate buffer. This solution is sonicated by means of a 60W sonicator (Company: Bioblock, under the ref. C72442) using a "cuphorn" type probe (Company: Bioblock, under the ref. C72438) so as to obtain a population of fragments which are predominantly 1 Kilobase in size.
An aliquot, corresponding to 108 bacteria in 10 μl, is then identified by hybridization according to the following procedure. Into a microtiter plate (Trade name Nunc 439454), is deposited a solution of the capture oligonucleotide probe (probe SEQ ID NO 6) at 1 ng/μl, in 1× PBS (0.15M NaCl, 0.05M sodium phosphate, pH 7.0). The plate is incubated for 2 h at 37° C. and then washed 3 times with 300 μl of PBST (PBS+detergent of the trade mark TWEEN from the company MERCK). The target, consisting of 10 μl of sonicated total DNA, is mixed with 70 μl of PBS salmon buffer 3× PBS+10 μg/ml of salmon sperm DNA, (Sigma company, under the ref. D9156)! and 10 μl of 2N sodium hydroxide. The mixture is neutralized 5 minutes later by addition of 10 μl of 2N acetic acid. The mixture is added to the well, in addition to 50 μl of a solution of the peroxydase-labeled detection probe conjugate based on SEQ ID NO 7, at the concentration of 0.1 ng/μl, in PBS horse buffer 3× PBS+10% horse serum, (Company: BioMerieux SA, ref. 55842)!.
The plate is incubated for 1 h at 37° C. and washed with 3×300 μl of PBS Tween 1× PBS+0.5% Tween 20 (Company: Merck, ref. 822184)!.
100 μl of OPD substrate (ortho-phenylenediamine from Cambridge Medical Biotechnology ref./456) in a specific buffer (0.055M citric acid, 0.1M Na 2 HPO 4 , pH 4.93) at the concentration of 4 mg/ml to which are added, immediately for use, H 2 O 2 at 30 volumes to 1/1000, are added per well. After reacting for 20 minutes, the enzymatic activity is blocked using 100 μl of 1N H 2 SO 4 and the reading is performed in a microplate reader of the trademark Axia Microreader (Company BioMerieux SA) at 492 nm.
This system generates no background since the well containing the salmon DNA of the hybridization buffer, which is sonicated in the same manner as the DNA of the test strains, does not generate any signal. The results relating to specificity are the same as those obtained in stage 3. This application of a nonradioactive probe indicates that the specificity of the sequence of the invention is conserved regardless of the hybridization procedure used.
__________________________________________________________________________SEQUENCE LISTING(1) GENERAL INFORMATION:(iii) NUMBER OF SEQUENCES: 21(2) INFORMATION FOR SEQ ID NO:1:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 340 bases(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: no(iv) ANTI-SENSE: no(vi) ORIGINAL SOURCE:(A) ORGANISM: Streptococcus pneumoniae(B) STRAIN: R800(viii) POSITION IN GENOME:(A) MAP POSITION: 24-26 minutes(ix) FEATURE:(A) NAME/KEY: repeating unit(B) LOCATION: 3..291(C) IDENTIFICATION METHOD: experimentally(xi) SEQUENCE DESCRIPTION: SEQ ID NO:1:GTTAACACTTTTCAAAAATCTCTTCAAACAACGTCAGCTTTGCCTTGCCGTATATATGTT60ACTGACTTCGTCAGTTCTATCTGCCACCTCAAAACGGTGTTTTGAGCTGACTTCGTCAGT120TCTATCCACAACCTCAAAACAGTGTTTTGAGCTGACTTCGTCAGTTCTATCCACAACCTC180AAAACAGTGTTTTGAGCTGACTTTGTCAGTCTTATCTACAACCTCAAAACAGTGTTTTGA240GCATCATGCGGCTAGCTTCTTAGTTTGCTCTTTGATTTTCATTGAGTATAAAAACAGATG300AGTTTCTGTTTTCTTTTTATGGACTATAAATGTTCAGCTG340(2) INFORMATION FOR SEQ ID NO:2:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 59 bases(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: no(iv) ANTI-SENSE: no(viii) ORIGINAL SOURCE:(A) ORGANISM: Streptococcus pneumoniae(B) STRAIN: R800(viii) POSITION IN GENOME:(A) MAP POSITION:(ix) FEATURE:(A) NAME/KEY: repeating unit(B) LOCATION: 1..59(C) IDENTIFICATION METHOD: experimentally(xi) SEQUENCE DESCRIPTION: SEQ ID NO:2:TAATACTCTTCGAAAATCTCTTCAAACCACGTCAGCGTCGCCTTGCCGTAGATATGTTA59(2) INFORMATION FOR SEQ ID NO:3:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 45 bases(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: no(iv) ANTI-SENSE: no(vi) ORIGINAL SOURCE:(A) ORGANISM: Streptococcus pneumoniae(B) STRAIN: R800(viii) POSITION IN GENOME:(A) MAP POSITION:(ix) FEATURE:(A) NAME/KEY: repeating unit(B) LOCATION: 1..45(C) IDENTIFICATION METHOD: experimentally(xi) SEQUENCE DESCRIPTION: SEQ ID NO:3:CTGACTTCGTCAGTTCTATCTACAACCTCAAAACAGTGTTTTGAG45(2) INFORMATION FOR SEQ ID NO:4:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 50 bases(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: no(iv) ANTI-SENSE: no(vi) ORIGINAL SOURCE:(A) ORGANISM: Streptococcus pneumoniae(B) STRAIN: R800(viii) POSITION IN GENOME:(A) MAP POSITION:(ix) FEATURE:(A) NAME/KEY: repeating unit(B) LOCATION: 1..50(C) IDENTIFICATION METHOD: experimentally(xi) SEQUENCE DESCRIPTION: SEQ ID NO:4:CAACCTGCGGCTAGCTTCCTAGTTTGCTCTTTGATTTTCATTGAGTATAA50(2) INFORMATION FOR SEQ ID NO:5:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 20 bases(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: no(iv) ANTI-SENSE: no(vi) ORIGINAL SOURCE:(A) ORGANISM: Streptococcus pneumoniae(B) STRAIN: R800(viii) POSITION IN GENOME:(A) MAP POSITION:(ix) FEATURE:(A) NAME/KEY: repeating unit(B) LOCATION: 1..20(C) IDENTIFICATION METHOD: experimentally(xi) SEQUENCE DESCRIPTION: SEQ ID NO:5:ACGTCARCKTYRCCTTRCCG20(2) INFORMATION FOR SEQ ID NO:6:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 22 bases(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: no(iv) ANTI-SENSE: no(vi) ORIGINAL SOURCE:(A) ORGANISM: Streptococcus pneumoniae(B) STRAIN: R800(viii) POSITION IN GENOME:(A) MAP POSITION:(ix) FEATURE:(A) NAME/KEY: repeating unit(B) LOCATION: 1..22(C) IDENTIFICATION METHOD: experimentally(xi) SEQUENCE DESCRIPTION: SEQ ID NO:6:TATYYACARYSTCAAAAYAGTG22(2) INFORMATION FOR SEQ ID NO:7:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 29 bases(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: no(iv) ANTI-SENSE: no(vi) ORIGINAL SOURCE:(A) ORGANISM: Streptococcus pneumoniae(B) STRAIN: R800(viii) POSITION IN GENOME:(A) MAP POSITION:(ix) FEATURE:(A) NAME/KEY: repeating unit(B) LOCATION: 1..29(C) IDENTIFICATION METHOD: experimentally(xi) SEQUENCE DESCRIPTION: SEQ ID NO:7:TAGTTTGCTCTTTGATTTTYATTGAGTAT29(2) INFORMATION FOR SEQ ID NO:8:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 20 bases(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: no(iv) ANTI-SENSE: no(vi) ORIGINAL SOURCE:(A) ORGANISM: Streptococcus pneumoniae(B) STRAIN: R800(viii) POSITION IN GENOME:(A) MAP POSITION:(ix) FEATURE:(A) NAME/KEY: repeating unit(B) LOCATION: 1..20(C) IDENTIFICATION METHOD: experimentally(xi) SEQUENCE DESCRIPTION: SEQ ID NO:8:ACGTCAGCTTTGCCTTGCCG20(2) INFORMATION FOR SEQ ID NO:9:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 20 bases(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: no(iv) ANTI-SENSE: no(vi) ORIGINAL SOURCE:(A) ORGANISM: Streptococcus pneumoniae(B) STRAIN: R800(viii) POSITION IN GENOME:(A) MAP POSITION:(ix) FEATURE:(A) NAME/KEY: repeating unit(B) LOCATION: 1..20(C) IDENTIFICATION METHOD: experimentally(xi) SEQUENCE DESCRIPTION: SEQ ID NO:9:CGGCAAGGCAAAGCTGACGT20(2) INFORMATION FOR SEQ ID NO:10:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 20 bases(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: no(iv) ANTI-SENSE: no(vi) ORIGINAL SOURCE:(A) ORGANISM: Streptococcus pneumoniae(B) STRAIN: R800(viii) POSITION IN GENOME:(A) MAP POSITION:(ix) FEATURE:(A) NAME/KEY: repeating unit(B) LOCATION: 1..20(C) IDENTIFICATION METHOD: experimentally(xi) SEQUENCE DESCRIPTION: SEQ ID NO:10:ATCTGCCACCTCAAAACGGT20(2) INFORMATION FOR SEQ ID NO:11:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 20 bases(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: no(iv) ANTI-SENSE: no(vi) ORIGINAL SOURCE:(A) ORGANISM: Streptococcus pneumoniae(B) STRAIN: R800(viii) POSITION IN GENOME:(A) MAP POSITION:(ix) FEATURE:(A) NAME/KEY: repeating unit(B) LOCATION: 1..20(C) IDENTIFICATION METHOD: experimentally(xi) SEQUENCE DESCRIPTION: SEQ ID NO:11:ACCGTTTTGAGGTGGCAGAT20(2) INFORMATION FOR SEQ ID NO:12:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 20 bases(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: no(iv) ANTI-SENSE: no(vi) ORIGINAL SOURCE:(A) ORGANISM: Streptococcus pneumoniae(B) STRAIN: R800(viii) POSITION IN GENOME:(A) MAP POSITION:(ix) FEATURE:(A) NAME/KEY: repeating unit(B) LOCATION: 1..20(C) IDENTIFICATION METHOD: experimentally(xi) SEQUENCE DESCRIPTION: SEQ ID NO:12:ATCCACAACCTCAAAACAGT20(2) INFORMATION FOR SEQ ID NO:13:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 20 bases(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: no(iv) ANTI-SENSE: no(vi) ORIGINAL SOURCE:(A) ORGANISM: Streptococcus pneumoniae(B) STRAIN: R800(viii) POSITION IN GENOME:(A) MAP POSITION:(ix) FEATURE:(A) NAME/KEY: repeating unit(B) LOCATION: 1..20(C) IDENTIFICATION METHOD: experimentally(xi) SEQUENCE DESCRIPTION: SEQ ID NO:13:ACTGTTTTGAGGTTGTGGAT20(2) INFORMATION FOR SEQ ID NO:14:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 20 bases(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: no(iv) ANTI-SENSE: no(vi) ORIGINAL SOURCE:(A) ORGANISM: Streptococcus pneumoniae(B) STRAIN: R800(viii) POSITION IN GENOME:(A) MAP POSITION:(ix) FEATURE:(A) NAME/KEY: repeating unit(B) LOCATION: 1..20(C) IDENTIFICATION METHOD: experimentally(xi) SEQUENCE DESCRIPTION: SEQ ID NO:14:ATCTACAACCTCAAAACAGT20(2) INFORMATION FOR SEQ ID NO:15:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 20 bases(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: no(iv) ANTI-SENSE: no(vi) ORIGINAL SOURCE:(A) ORGANISM: Streptococcus pneumoniae(B) STRAIN: R800(viii) POSITION IN GENOME:(A) MAP POSITION:(ix) FEATURE:(A) NAME/KEY: repeating unit(B) LOCATION: 1..20(C) IDENTIFICATION METHOD: experimentally(xi) SEQUENCE DESCRIPTION: SEQ ID NO:15:ACTGTTTTGAGGTTGTAGAT20(2) INFORMATION FOR SEQ ID NO:16:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 20 bases(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: no(iv) ANTI-SENSE: no(vi) ORIGINAL SOURCE:(A) ORGANISM: Streptococcus pneumoniae(B) STRAIN: R800(viii) POSITION IN GENOME:(A) MAP POSITION:(ix) FEATURE:(A) NAME/KEY: repeating unit(B) LOCATION: 1..20(C) IDENTIFICATION METHOD: experimentally(xi) SEQUENCE DESCRIPTION: SEQ ID NO:16:GAGCATCATGCGGCTAGCTT20(2) INFORMATION FOR SEQ ID NO:17:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 20 bases(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: no(iv) ANTI-SENSE: no(vi) ORIGINAL SOURCE:(A) ORGANISM: Streptococcus pneumoniae(B) STRAIN: R800(viii) POSITION IN GENOME:(A) MAP POSITION:(ix) FEATURE:(A) NAME/KEY: repeating unit(B) LOCATION: 1..20(C) IDENTIFICATION METHOD: experimentally(xi) SEQUENCE DESCRIPTION: SEQ ID NO:17:AAGCTAGCCGCATGATGCTC20(2) INFORMATION FOR SEQ ID NO:18:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 20 bases(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: no(iv) ANTI-SENSE: no(vi) ORIGINAL SOURCE:(A) ORGANISM: Streptococcus pneumoniae(B) STRAIN: R800(viii) POSITION IN GENOME:(A) MAP POSITION:(ix) FEATURE:(A) NAME/KEY: repeating unit(B) LOCATION: 1..20(C) IDENTIFICATION METHOD: experimentally(xi) SEQUENCE DESCRIPTION: SEQ ID NO:18:GCTAGCTTCTTAGTTTGCTC20(2) INFORMATION FOR SEQ ID NO:19:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 20 bases(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: no(iv) ANTI-SENSE: no(vi) ORIGINAL SOURCE:(A) ORGANISM: Streptococcus pneumoniae(B) STRAIN: R800(viii) POSITION IN GENOME:(A) MAP POSITION:(ix) FEATURE:(A) NAME/KEY: repeating unit(B) LOCATION: 1..20(C) IDENTIFICATION METHOD: experimentally(xi) SEQUENCE DESCRIPTION: SEQ ID NO:19:GAGCAAACTAAGAAGCTAGC20(2) INFORMATION FOR SEQ ID NO:20:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 20 bases(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: no(iv) ANTI-SENSE: no(vi) ORIGINAL SOURCE:(A) ORGANISM: Streptococcus pneumoniae(B) STRAIN: R800(viii) POSITION IN GENOME:(A) MAP POSITION:(ix) FEATURE:(A) NAME/KEY: repeating unit(B) LOCATION: 1..20(C) IDENTIFICATION METHOD: experimentally(xi) SEQUENCE DESCRIPTION: SEQ ID NO:20:TGCTCTTTGATTTTCATTGA20(2) INFORMATION FOR SEQ ID NO:21:(i) SEQUENCE CHARACTERISTICS:(A) LENGTH: 20 bases(B) TYPE: nucleic acid(C) STRANDEDNESS: single(D) TOPOLOGY: linear(ii) MOLECULE TYPE: DNA (genomic)(iii) HYPOTHETICAL: no(iv) ANTI-SENSE: no(vi) ORIGINAL SOURCE:(A) ORGANISM: Streptococcus pneumoniae(B) STRAIN: R800(viii) POSITION IN GENOME:(A) MAP POSITION:(ix) FEATURE:(A) NAME/KEY: repeating unit(B) LOCATION: 1..20(C) IDENTIFICATION METHOD: experimentally(xi) SEQUENCE DESCRIPTION: SEQ ID NO:21:TCAATGAAAATCAAAGAGCA20__________________________________________________________________________
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The invention relates to a fragment of the genomic DNA of Streptococcus pneumoniae, a probe capable of specifically hybridizing with the genomic DNA of Screptococcus pneumoniae, a specific primer for the amplification, by polymerization, of the genomic DNA, a reagent and a method which are used with the probe and, optionally, the primer, for specifically detecting Streptococcus pneumoniae in a biological sample. The probe of the invention is a nucleotide sequence having at least 70% homology with at least a portion of a consensus sequence of the genomic DNA of Streptococcus pneumoniae, this consensus sequence being chosen from the nucleotide sequences SEQ ID NO 2, SEQ ID NO 3, SEQ ID NO 4, which are identified in the description, and their respective complementary sequences.
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BACKGROUND OF THE INVENTION
This application relates to a method of repairing a full hoop structure with a welding process, wherein heat treating is performed both at the location of the weld, and at a diametrically opposed location.
Welding methods are sometimes necessary to repair metallic structures. As an example, a cast part may have a defect such as shrinkage that may have occurred in a cast mold. Alternatively, small cracks may form in the part.
Such operations are often used in components for gas turbine engines. Structures that could be called “full hoop,” or structures that surround a central axis for 360°, often require such welding procedures. Examples of such parts in a gas turbine engine would be a diffuser case and a turbine exhaust case.
The weld being performed at a location on the part may cause an unacceptably high residual stress. In the prior art, this stress has been relieved by some post-weld heat treatment.
In one prior art method, the entire structure has been heated isothermally to heat-treat temperatures. Heating isothermally does not induce additional thermal stress at the weld, so the residual stress remains constant until actual heat treatment takes place. This “global” heating can affect dimensions that have been “machined” into the part by causing their residual stresses to also relax. In many cases, it has not been found practical due to cost and complexity to fixture the part during heat treatment to hold these dimensions constant.
Thus, localized heat treatment has also been utilized to avoid loss of dimensions. Local heat treatment can have unforeseen and potentially detrimental effects on the intended stress relaxation. The region being heated locally will expand due to its temperature change. The surrounding non-heated material will resist this expansion causing the heated area to become more compressively loaded. Since the residual stress due to weld is tensile, the net effect of local heating is to temporarily reduce the value of the tensile stress in the weld. If sufficient care is not exercised, it is possible to reduce the value of the tensile stress so much so as to eliminate it completely. In this case, subsequent heat treatment for stress relaxation would be ineffective since the stress would already be reduced to zero. Note that the full value of the residual stress in this case would return when the locally applied temperature was removed.
Also of concern, would be a situation in which the weld stress was reduced by local heating through zero and into a state of compression. This stress would relax during subsequent heat treatment, but this is far from the original intent of the heat treatment process, which was to reduce the tensile residual stress associated with the weld.
SUMMARY OF THE INVENTION
In the disclosed embodiment of this invention, a weld repair is made on a part with a full hoop structure. After the weld has been completed, heat-treating is performed at the location of the weld, and at the same time, at a second opposed location. In a disclosed embodiment, the second location is diametrically opposed to the weld location. This heat-treating is preferably confined to as narrow a band as possible through the weld and its heat affected zone, and in a similar manner, at an opposed position to it. Furthermore, the heat-treating preferably occurs along an entire axial length of the part.
The opposed bands of heat-treating eliminate the compressive stresses mentioned above from forming. This allows the modified local heat treatment to mimic the beneficial effect of a global heat treatment as mentioned above while avoiding the inherent problems.
While in the disclosed embodiment the part is a full hoop part, the present invention is more powerful, and extends beyond any particular shape of part. In fact, an arbitrarily shaped part could benefit from this present invention. In an arbitrarily shaped part, an area of material on the part would be identified about which the part would thermally expand while not creating additional stress in the part at a weld treatment location. The weld treatment would be provided, and simultaneously, a local heat treatment would be provided at an area of the weld treatment, and at the identified area.
In other optional embodiments, the second band could be a plurality of bands, which are displaced from the diametrically opposed location. As an example, two separate bands spaced equally about a location spaced 180° from the weld treatment area could be utilized rather than a single second band.
In yet another embodiment, the second band can extend for a greater circumferential extent than the band about the weld treatment. In this manner, the heat treating on the second band can be at a lower temperature. By utilizing a lower temperature, the potential resultant dimensional changes in that second region can be reduced. Such dimensional changes are related to temperature, and thus being able to utilize a lower temperature, albeit over a larger area, might prove beneficial under certain applications.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 schematically shows a gas turbine engine.
FIG. 2 is a schematic view of a full hoop part.
FIG. 3 is a cross-sectional view of a heat treatment occurring on the mentioned part.
FIG. 4 shows yet another embodiment.
FIG. 5 shows yet another embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A gas turbine engine 10 is illustrated in FIG. 1 extending along an axial center line 12 . A fan section 14 is upstream of a compressor section 16 , a combustion section 18 , and a turbine section 11 . As is known, many components of a gas turbine engine 10 could be said to have a “full hoop” structure. The full hoop is defined as a structure that surrounds the axial center line 12 for 360°. An example of such full hoop structures found in the gas turbine engine 10 would include a diffuser case located downstream of the compressor, or a turbine exhaust case located downstream of the turbine section 11 . The term “full hoop” should not be taken as requiring that the component would be cylindrical. In fact, the disclosed components could be better described as somewhat conical. Even that shape is not a limitation on the definition of “full hoop” which could extend to non-symmetrical structures, or structures with complex surfaces and multi-faceted shapes at their outer surfaces.
As shown in FIG. 2 , such a part 50 can have defects such as a crack shown at 52 . Other type defects may be a casting defect such as may be caused by shrinkage. A worker of ordinary skill in the art would recognize many of the known defects, which could require welding repair treatment.
As shown in FIG. 3 , a weld treatment 53 is being applied schematically by welding tool 60 at the crack 52 . With the present invention, and after completion of the welding treatment, two narrow bands of heat treatment are applied at diametrically opposed locations 54 and 56 . Preferably the circumferential extent of the bands is selected to only be wide enough to provide the stress relief at the weld joint 53 along the defect 52 . Thus, the bands may well have the same circumferential width. As shown, heating structures 58 create these two heat treat locations. The heating structures may be induction coils, radiant lamps, gas burners, etc. The heat treatment can be on the order of 1500° F., although the heat treat temperatures may be as known in the art. The bands 54 and 56 extend along the entire length of the part 50 , as shown in FIG. 2 . Of course, it may also be that the bands do not extend for the entire length of the part.
The present invention, by utilizing the two diametrically opposed bands, achieves the benefits provided by the global heating of the prior art, but also avoids the problems of global heating as encountered in the prior art.
Also, while the present invention is disclosed as being directed to full hoop parts, it would have benefits in certain parts that do not have the full hoop structure as defined above. Arbitrarily shaped parts could benefit from the present invention by heat treating two distinct zones, to allow the numerical value of weld residual stress to be heat treated, while greatly reducing or eliminating the liability of resultant dimensional changes. For non-full hoop structures, a line or plane of material to be locally heat treated as the second band, is the line or plane about which the structure would thermally expand without creating additional stress in the component at the weld. A worker of ordinary skill in this art can determine this line or plane with structural analysis.
FIG. 4 shows another embodiment wherein the “second band” is actually provided by two separate bands 202 and 204 . As can be appreciated, the two separate bands are disclosed as being spaced equally about the point P spaced 180° from the weld treatment area T. By positioning these separate bands about the point P, the beneficial effects provided by the above-disclosed embodiment can be achieved.
FIG. 5 shows yet another embodiment wherein the circumferential extent of the second band 300 is wider than the circumferential extent of the weld band 302 . The temperature provided at the second band 300 can be lower, such that potential resultant dimensional changes in this second band are reduced.
Again, a worker of ordinary skill in the art would recognize how to incorporate the optional embodiments of FIGS. 4 and 5 to best effect.
Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
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A unique heat treat method for relieving stresses caused by a repairing weld joint in a full hoop part heat treats locally, at the location of the weld joint, and at a diametrically opposed location. By providing the diametrically opposed heat treat location, the present invention relieves stresses caused by the weld joint, without creating any additional residual stress in the weld joint.
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CROSS REFERENCE TO RELATED APPLICATIONS
This application is divisional patent application of U.S. patent application Ser. No. 09/583,247, filed May 31, 2000, the disclosure of which is incorporated herein by reference.
GOVERNMENTAL INTERESTS
This invention was made with government support under grant CA 78039 awarded by the National Institutes of Health. The government has certain rights in this invention.
FIELD OF THE INVENTION
The present invention relates to fluorous tagging or protecting compounds and to methods of use thereof, and especially, to fluorous tagging compounds suitable for use with hydyroxy- and amine-bearing organic compounds.
BACKGROUND OF THE INVENTION
In traditional organic chemistry, compounds are synthesized as pure substances through well-planned reactions and careful separation. However, in a number of fields, including drug discovery, catalyst design and new material development, tens of thousands of organic compounds must be synthesized and tested to discover a few active ones. In the pharmaceutical industry, for example, synthesizing such a large number of compounds in the traditional way is too slow compared to the rapid emergence of new biological targets. The productivity of orthodox solution (liquid) phase organic synthesis is severely limited by tedious separation processes for the purification of products. Techniques integrating organic reactions with rapid purification/separation procedures are thus highly desirable.
Recently, fluorous synthetic and separation techniques have attracted the interest of organic chemists. In fluorous synthetic techniques, reaction components are typically attached to fluorous groups or tags such as perfluoroalkyl groups to facilitate the separation of products. Organic compounds are readily rendered fluorous by attachment of an appropriately fluorinated phase label or tag. In general, fluorous-tagged molecules partition preferentially into a fluorous phase while non-tagged ones partition into an organic phase.
The fluorous tag preferably fulfills a double role as protective group and phase tag and is removed in the final step(s) of the synthesis. The viability of a fluorous synthesis plan depends greatly on the availability of suitable fluorous protecting groups, but only a few fluorous tags are currently available.
In that regard, the fluorous phase label or tag most often used in fluorous synthesis has been the silane (C 10 F 21 CH 2 CH 2 ) 3 SiBr 1. In general, the silane is attached to alcohol-bearing substrates using standard conditions to result in a silyl ether, and can be cleaved with fluoride. The silane, however, cannot be recycled. In addition, the powerful electron withdrawing effect of three fluorous chains makes the silyl ether rather labile towards nucleophiles and other polar reactions. Thus, although fluorous synthetic and/or separation techniques are promising, such techniques are currently limited by a lack of availability of suitably versatile fluorous tags.
It is thus very desirable to develop improved fluorous tagging compounds.
SUMMARY OF THE INVENTION
For the further development of fluorous phase chemistry into a practical strategy in, for example, combinatorial and parallel synthesis, a variety of fluorous phase labels must be made available. The present invention provides fluorous tags that can be prepared in large quantity, can be installed and removed from a substrate using mild reaction conditions, and can be recyclable after cleavage. In addition, the fluorous tags of the present invention are tolerant, as a group, to a wide range of reaction conditions, such that an appropriate label can be chosen which is amenable to substantially any given sequence of reactions.
The resulting fluorous “tagged” compound can be used in a wide variety of fluorous reaction and/or separation techniques. Several fluorous reaction and separation techniques are disclosed, for example, in U.S. Pat. Nos. 5,859,247 and 5,777,121, the disclosures of which are incorporated herein by reference. The tagging compounds of the present invention are particularly suitable for tagging of compounds bearing hydroxyl groups or nitrogen groups such as amine groups.
As used herein, the term “fluorous”, when used in connection with an organic (carbon-containing) molecule, moiety or group, refers generally to an organic molecule, moiety or group having a domain or a portion thereof rich in carbon-fluorine bonds (for example, fluorocarbons or perfluorocarbons, fluorohydrocarbons, fluorinated ethers, fluorinated amines and fluorinated adamantyl groups). For example, perfluorinated ether groups can have the general formula —[(CF 2 ) x O(CF 2 ) y ] z CF 3 , wherein x, y and z are integers. Perfluorinated amine groups can, for example, have the general formula —[(CF 2 ) x (NR a )CF 2 ) y ] z CF 3 , wherein R a can, for example, be (CF 2 ) n CF 3 , wherein n is an integer. Fluorous ether groups and fluorous amine groups suitable for use in the present invention need not be perfluorinated, however. The term “fluorous compound,” thus refers generally to a compound comprising a portion rich in carbon-fluorine bonds. As used herein, the term “perfluorocarbons” refers generally to organic compounds in which all hydrogen atoms bonded to carbon atoms have been replaced by fluorine atoms. The terms “fluorohydrocarbons” and “hydrofluorocarbons” include organic compounds in which at least one hydrogen atom bonded to a carbon atom has been replaced by a fluorine atom. A few examples of suitable fluorous groups Rf for use in the present invention include, but are not limited to, —C 4 F 9 , —C 6 F 13 , —C 8 F 17 , —C 10 F 21 , —C(CF 3 ) 2 C 3 F 7 , —C 4 F 8 CF (CF 3 ) 2 , —CF 2 CF 2 OCF 2 CF 2 OCF 3 , —CF 2 CF 2 (NCF 2 CF 3 ) CF 2 CF 2 CF 3 , and fluorous adamantyl groups.
As used herein, the term “tagging” refers generally to attaching a fluorous moiety or group (referred to as a “fluorous tagging moiety” or “tagging group”) to a compound to create a “fluorous tagged compound”. Separation of the tagged compounds of the present invention is achieved by using fluorous separation techniques that are based upon differences between/among the fluorous nature of a mixture of compounds. As used herein, the term “fluorous separation technique” refers generally to a method that is used to separate mixtures containing fluorous molecules or organic molecules bearing fluorous domains or tags from each other and/or from non-fluorous compounds based predominantly on differences in the fluorous nature of molecules (for example, size and/or structure of a fluorous molecule or domain or the absence thereof). Fluorous separation techniques include but are not limited chromatography over solid fluorous phases such as fluorocarbon bonded phases or fluorinated polymers. See, for example, Danielson, N. D. et al., “Fluoropolymers and Fluorocarbon Bonded Phases as Column Packings for Liquid Chromatography,” J. Chromat., 544, 187-199 (1991). Examples of suitable fluorocarbon bonded phases include commercial Fluofix® and Fluophase™ columns available from Keystone Scientific, Inc. (Bellefonte, Pa.), and FluoroSep™-Octyl from ES Industries (Berlin, N.J.). Other fluorous separation techniques include liquid-liquid based separation methods such as liquid-liquid extraction or countercurrent distribution with a fluorous solvent and an organic solvent.
Preferably, the molecular weight of the fluorous tags of the present invention does not exceed about 2,500. More preferably, the molecular weight does not exceed about 1,750. Even more preferably the molecular weight does not exceed about 1200. Compounds may bear more than one fluorous tag of the present invention.
In one aspect, the present invention provides a method of increasing the fluorous nature of a compound, including the step of reacting the compound with at least one second compound having the formula:
wherein Rf is a fluorous group and m is 0, 1 or 2 (that is, the ring can be a five-, six-, or seven-membered ring). The fluorous group can, for example be a fluorohydrocarbon group (for example, fluorous alkyl groups, including fluorous adamantyl groups), a perfluorocarbon group, a fluorinated ether group or a fluorinated amine group. Perfluoroadamantyl group suitable for use in the present invention can, for example, have the following formulas:
As used herein, the terms “alkyl”, “aryl” and other substituent groups refer generally to both unsubstituted and substituted groups unless specified to the contrary. Unless otherwise specified, alkyl groups are hydrocarbon groups and are preferably C 1 -C 15 (that is, having 1 to 15 carbon atoms) alkyl groups, and more preferably C 1 -C 10 alkyl groups, and can be branched or unbranched, acyclic or cyclic. The term “aryl” refers to phenyl (Ph) or napthyl, substituted or unsubstituted. The term “alkylene” refers to bivalent forms of alkyl.
The groups set forth above, can be substituted with a wide variety of substituents. For example, alkyl groups may preferably be substituted with a group or groups including, but not limited to aryl groups. Aryl groups may preferably be substituted with a group or groups including, but not limited to, alkyl groups or other aryl groups.
In another aspect, the present invention provides a method of increasing the fluorous nature of a compound, including the step of reacting the compound with at least one second compound having the formula:
wherein Rf is a fluorous group as defined above, R 1 is a an alkyl group or an aryl group and m is 0, 1 or 2.
A method of increasing the fluorous nature of a compound, including the step of reacting the compound with at least one second compound having the formula:
wherein Rf 1 and Rf 2 are independently, the same or different, fluorous groups, Rs 1 is a spacer group, d is 1 or 0 (that is, the spacer group can be present or absent), Rs 2 is a spacer group, a is 1 or 0, R 2 is a H, an alkyl group or an aryl group, R 3 is H or —Rs 3 e Rf 3 , wherein, Rs 3 is a spacer group, e is 1 or 0, and Rf 3 is a fluorous group. Numerous types of spacer groups or linkages can be used in the present invention. Examples of spacer groups suitable for use herein include, but are not limited to, alkylene groups (preferably, C 1 -C 6 alkylene groups), 1,2-, 1,3-, or 1,4-divalent phenyl groups or alkoxy alkylene groups (for example, —O(CH 2 ) x —). As used herein, the term “alkylene” refers generally to a bivalent form of an alkyl group (for example, —(CH 2 ) m —) Alkylene groups may be substituted or unsubstituted.
The present invention also provides a method of increasing the fluorous nature of a compound, including the step of reacting the compound with at least one second compound having the formula:
wherein Rf 1 and Rf 2 are independently, the same or different, fluorous groups, Rs 1 is a spacer group, d is 1 or 0 (that is, the spacer group can be present or absent), Rs 2 is a spacer group, a is 1 or 0, R 4 is an alkyl group or an aryl group, R 5 is an alkyl group or an aryl group, R 6 is H, an alkyl group, or a fluorinated alkyl group, and X is Cl, Br or I.
In another aspect, the present invention provides a method of increasing the fluorous nature of a compound, including the step of reacting the compound with at least one second compound having the formula:
wherein Rf 1 is a fluorous group, Rs 1 is a spacer group, d is 1 or 0, R 4 is an alkyl group or an aryl group, R 5 is an alkyl group or an aryl group, and X is Cl, Br or I.
The present invention further provides a compound having the formula:
The present invention also provides a compound having the formula:
The present invention also provides a compound having the formula:
The present invention also provides a compound having the formula:
The present invention further provides a compound having the formula:
In another aspect, the present invention provides a method of activating an anomeric sulfoxide to react with an alcohol to form a corresponding ether comprising the step of mixing the anomeric sulfoxide with Cp 2 ZrCl 2 , AgClO 4 , and the alcohol. The anomeric sulfoxide can, for example, have the formula:
In still another aspect, the present invention provides a method of carrying out a reaction comprising the steps of:
attaching a fluorous tag to a substrate that is bound to a solid support;
cleaving the fluorous-tagged substrate from the solid support while retaining the fluorous tag attached thereto;
reacting the cleaved, fluorous-tagged substrate in a liquid phase reaction to synthesize a fluorous-tagged product; and
separating the fluorous-tagged product from other compounds using a fluorous separation technique.
The method may further include the step of cleaving the fluorous tag from the fluorous tagged product. In one embodiment, the fluorous tag has the formula:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrate synthesis of one embodiment of a fluorous glycosyl iodide tagging compound of the present invention and fluorous-tagged ethers synthesized therefrom.
FIG. 2 illustrate synthesis of one embodiment of a fluorous sulfoxide tagging compound of the present invention and fluorous-tagged ethers synthesized therefrom.
FIG. 3 illustrates synthesis of one embodiment of a fluorous vinyl ether tagging compound of the present invention and fluorous tagged ethers produced therefrom.
FIG. 4 illustrates synthesis of one embodiment of a fluorous alkoxysilyl tagging compound of the present invention and fluorous tagged ethers produced therefrom.
FIG. 5 illustrates the tagging of a number of alcohols with the fluorous alkoxysilyl tag of FIG. 4 and subsequent regeneration of the alcohol and recycling of the fluorous alkoxysilyl tag.
FIGS. 6 and 7 illustrate synthesis of combinatorial mixtures using the fluorous tag of FIG. 3 .
FIG. 8 illustrates characterization of several products of the synthesis of FIGS. 6 and 7 (peaks 1-6 correspond to compounds 43-48, respectively).
FIG. 9 illustrates an example of conversion from a solid phase synthesis to a liquid phase synthesis using the fluorous tag of FIG. 4 .
DETAILED DESCRIPTION OF THE INVENTION
Fluorous-Labeled Tetrahydropyranyl (THP F ) Ethers
In one aspect the present invention provides a series of fluorous-labeled tetrahydropyranyl (THP F ) ethers that are stable to basic and nucleophilic reaction conditions and become readily recyclable after cleavage. A perfluoroalkyl-substituted dihydropyran which can be installed on any hydroxy-bearing substrate via acid catalysis in the same way a standard THP protection is provided as a model.
Initially, dihydropyran 4 was synthesized in one step from perfluorooctyl iodide 3 and dihydropyran 2 in 46% yield as illustrate in FIG. 1 . However, treatment of alcohols with an excess of 4 using a variety of acids, solvents, and temperatures failed to give any of the desired acetal 5. The loss of reactivity of the vinyl ether is believed to be a result of the powerful electron withdrawing effect of the perfluoroalkyl chain.
A second route involved glycosylation methodology. Glycosyl fluorides have been effectively activated by a Cp 2 ZrCl 2 —AgClO 4 reagent system. Suzuki, K. Pure Appl. Chem. 1994, 66, 1557. Flourous glycosyl iodide 6 was accessible in one step from perfluorooctyl iodide 3 with excess dihydropyran and stoichiometric Na 2 S 2 O 4 /NaHCO 3 under phase transfer conditions in 64% yield. Unfortunately, this reaction was often irreproducible, and was typically plagued by formation of hemiacetal 7. Use of catalytic Raney Nickel in refluxing THF gave 6 more reliability in 32-38% yield. Addition of a slight excess of 6 to a solution of one equivalent of Cp 2 ZrCl 2 , two equivalents of AgClO 4 , and one equivalent of an alcohol gave good yields of fluorous THP labeled products 8, presumably via an intermediate highly reactive oxonium species. Deprotection via transacetalization with methanol and catalytic para-toluenesulfonic acid proceeded to give the free alcohol in 80-95% yield, as well as the transacetalization product 9. However, attempts to recylcle methyl THP ether 9 to iodopyran 6 have yet to be successful. Application of trimethylsilyl iodide (TMSI) and several of its in situ prepared variants led in all cases to the undesired elimination product 4 as the primary product.
A sulfoxide method, however, has proven to be a mild and effective means for constructing glycosidic linkages. See Yan, L.; Kahne, D. J. Am. Chem. Soc. 1996, 118, 9239, and references cited therein. The synthesis of fluorous tetrahydropyranyl (THP F ) ethers of the present invention using this technique, began with the direct synthesis of methyl THP ether 9 from perfluorooctyl iodide 3 and dihydropyran 2. Treatment of a methanolic solution of 3 and 5 mol % [CpFe(CO) 2 ] 2 (cyclopentadienyl iron dicarbonyl dimer) with 1.5 equiv of dihydropyran and 1.1 equiv of Et 3 N at room temperature gave 9 in 83% yield. Conversion of 9 to the phenylthioacetal 10 was first accomplished using Nicolaou's method (5 equiv PhSSiMe 3 (phenylthiotrimethylsilane), 1.2 equiv Me 3 SiOTf (trimethylsilyltrifluoromethanesulfonate)) to give 10 in 60% yield. Nicolaou, K. C.; Seitz, S. P.; Papahatjis, D. P. J. Am. Chem. Soc. 1983, 105, 2430. Alternatively, heating 9 in a 1:1 mixture of PhSH (thiophenol) and toluene at 100° C. with 1 equiv of para-toluenesulfonic acid gave 10 in 61% yield. Oxidation of sulfide 10 with a Na 2 HPO 4 -buffered solution of meta-chloroperoxybenzoic acid in dichloromethane at 0° C. provided fluorous sulfoxide tagging compound 11 as a 1.5:1 mixture of anomers in 72% yield. Subsequent conversion utilized the major, more reactive cis-isomer. Trans-11 could be recycled to a 1:1 mixture of anomers in thiophenol/dioxane (1:1) at 95° C. in the presence of a catalytic amount of HgSO 4 .
Attempted glycosylation of alcohols with 11 using the standard triflic anhydride/2,6-di-tert-butyl-4-methyl pyridine reagent system gave low yields of 8 contaminated with large amounts of a dihydropyran elimination product 4. In contrast, treatment of a 1:2:1 mixture of Cp 2 ZrCl 2 , AgClO 4 , and alcohol at −20° C. with 1.5-2.5 equivalents of 11 provided after 8-10 h the desired fluorous THP labeled ethers 12-20 illustrated in FIG. 2 (ROTHP F ) in good yields for 1° and 2° alcohols. In addition, deprotection of the THP F -ethers and recycling of the protective group was accomplished by a transacetalization reaction using 25 mol % para-toluenesulfonic acid in MeOH:THF (2:1) at 70° C. for 20-30 h to give good yields of recovered alcohols and 9.
Purification of most THP F -ethers was accomplished simply by dissolving the crude product in MeCN and extracting five times with FC-72. FC-72 is a fluorocarbon solvent commercially available (3M) which includes perfluorohexane (C 6 F 14 ) isomers (bp 56° C.). Concentration of the fluorous extracts yielded the fluorous product, which contained small amounts of a dihydropyran elimination product 4, as well as trace amounts of unreacted sulfoxide 11. After this extraction, only minor amounts of the fluorous product remained in the MeCN layer. The crude deprotection mixture, treated with the same MeCN/FC-72 extraction procedure, gave the fluorous methyl-THP ether 8 in the FC-72 extracts, while the deprotected alcohol was found in the organic layer. As the organic mass or the polarity of a fluorous THP-labeled substrate becomes larger, however, simple liquid-liquid extraction becomes inefficient. Solid phase extraction by filtration through fluorous reverse-phase (FRP) silica gel was found to be effective for these cases. See Curran, D. P.; Hadida, S.; He, M. J. Org. Chem. 1997, 62, 6714. The rather polar 5 is almost insoluble in FC-72. This is advantageous in terms of separation of excess 11 during extractive purification of THP F -labeled alcohols, but also suggests a sufficiently polar moiety on the substrate to be protected may overpower the fluorous nature of the protected product. Fluorous THP-labeled cholesterol and methyl mandelate could not be fully extracted from MeCN with multiple (15) FC-72 extractions. Loading of the crude product onto a MeCN-wetted FRP-SiO 2 column, washing first with MeCN to elute organic components, then with FC-72 to elute the fluorous labeled compounds, conveniently allowed separation of THP F -labeled ethers from organic side products.
The recyclable fluorous THP tag or protecting group enables simple purification of small molecules by liquid-liquid extraction with FC-72/MeCN, and of larger or more polar molecules by solid phase extraction with fluorous reverse phase silica gel.
Fluorous Vinyl Ether Tags
In another aspect, the present invention provides a recyclable fluorous vinyl ether tagging or protecting group that is attached and removed under mildly acidic conditions.
A representative example of the synthesis of a fluorous vinyl ether tagging compound is illustrated in FIG. 3 . The synthesis of vinyl ether 23 begins with commercially available iodide 21. Formation of the Grignard reagent from 21 was effectively accomplished with sonication for the reaction initiation. Thus, treatment of an ether suspension of excess magnesium powder with 0.1 equivalents of 21, sonication for 20 minutes, and subsequent addition of an additional 2.4 equivalents of 21 in Et 2 O provided the Grignard reagent after a two hour reflux period. Dropwise addition of one equivalent of ethyl formate to the reaction mixture and further refluxing for 5 h gave the crude fluorous alcohol 22 after standard workup. This compound was conveniently purified by washing the crude solid with dichloromethane to give a 93% yield of 22. Vinylation (See Faulkner, D. J.; Petersen, M. R. J. Am. Chem. Soc. 1973, 95, 553) of 22 with 0.5 equivalents of mercuric acetate in a 1:1 mixture of ethyl vinyl ether and FC-72 at 45° C. for 40 h gave fluorous vinyl ether tagging compound 23 in 51% yield, with 42% recovered alcohol 22 (88% yield based on recovered starting material). The extremely apolar 23 could be isolated by filtration of the crude product mixture through a short pad of SiO 2 with hexanes, since the RF value of 23 is 0.9 in hexane, while 22 has an R F close to zero in hexane. The R f value of a compound is a measure of the relative polarity of the compound in a given solvent system. Thus, a compound with R f =1 is very nonpolar relative to a compound with R f =0, which would be considered very polar. The unreacted 22 can then be resubjected to the vinylation reaction, allowing for a ˜70% conversion to 23 after two runs. Accordingly, vinyl ether 23 is readily prepared in multigram quantities.
Protection of alcohols with 23 proceeds under mildly acidic conditions. Treatment of an Et 2 O solution of 1 equivalent of a primary alcohol and 3 equivalents of 23 with 5 mol % of camphorsulfonic acid for 3 h at room temperature provided the desired protected alcohols 24 (ROAE F ) in 84-93% yields, with the majority of the excess of vinyl ether recoverable. Secondary and even tertiary alcohols are similarly protected in good yields using THF as solvent at 65° C. for 30-45 min. The moderate yield obtained for protection of tert-butyl alcohol compares nonetheless well to the protection of this sterically hindered and volatile substrate with the fluorous THP F lable discussed above. The alkoxy ethyl (AE F ) fluorous label could also be installed on the nitrogen atom of an aniline. All protected and fluorous-tagged substrates were purified from excess 23 by column chromatography on SiO 2 . Separation was generally very straightforward as a result of the considerable RF-differences between 23 and 24, and the pre-purification of the reaction mixture from organic impurities by extraction with FC-72.
Deprotection of fluorous acetals 25-31 proceeded under mild conditions as well. Treatment of the protected substrates in a 1:1 solution of Et 2 O and MeOH with 5 mol % of camphorsulfonic acid gave, after 1 h, excellent yields of deprotected substrates as well as a quantitative recovery of fluorous alcohol 22 (see FIG. 3 ). After completion of the reaction, the products were isolated in pure form by simple 3-phase extraction (reaction mixture/saturated aqueous NaHCO 3 /FC-72). Alcohol 22 can be resubjected to vinylation to give 23 and thus is efficiently recycled.
The recyclable, highly fluorous acetal protecting group have broad applications in fluorous synthesis as well as in fluorous/solid phase combinations and other parallel synthesis strategies. The precursor vinyl ether 23 can be prepared in large quantities in a straightforward two step reaction sequence. Primary, secondary, and tertiary alcohols can be protected in good to excellent yields. The N-protection of 2-fluoroaniline also demonstrates the feasibility of using 23 with amines. After protection with the AE F -groups of the present invention, a compound is capable of undergoing a series of reactions in which purification of products can, for example, be accomplished by simple liquid-liquid extraction with FC-72 or filtration through fluorous reverse-phase SiO 2 . Deprotection occurs under mild acidic conditions, and the fluorous label is easily isolated and effectively recycled.
Compared to the THP F -function described above, the AE F -groups of the present invention are more readily cleaved and recycled and have a higher affinity toward the fluorous environment. There is a direct correlation between the number of fluorine atoms in a molecule and its selective solubility in perfluorinated solvents. With the exception of small organic molecules, most compounds protected with the THP F -function were insufficiently fluorous for efficient liquid-liquid extraction and rapid purification required fluorous reverse-phase SiO 2 (FRP). In particular in preparative scale synthesis, the broad use of FRP chromatography is currently limited by the high costs of the stationary phase. Because of the higher level of fluorination of the AE F -group, all substrates shown in FIG. 3 could be purified by simple liquid-liquid extraction. The AE F -group tags or labels are, therefore, ideally suited for the protection of large quantities or high molecular weight organic molecules under basic and/or nucleophilic reaction sequences. Application of the AE F -fluorous tagging compounds of the present invention to a combinatorial synthesis of analogs of the antimitotic natural product curacin A is discussed below.
tert-Butyl-phenyl-1H,1H,2H,2H-heptadecafluorodecyloxysilyl (BPFOS) Tags
In still another aspect, the present invention provides fluorous alkoxysilyl tagging groups. In general, tert-Butyl-phenyl-1H,1H,2H,2H-heptadecafluorodecyloxysilyl (BPFOS) ethers resulting from reaction of the fluorous alkoxysilyl tagging groups of the present invention with alcohols were found to be surprisingly acid stable and allow simple protection-purification-deprotection schemes by liquid-liquid extraction with FC-72/CH 3 CN or by solid phase extraction with fluorous reverse phase silica gel.
Given the acid stability of bis-alkoxysilyl ethers, the viability of fluorous alkoxysilyl groups as fluorous tagging/protecting groups for alcohols was explored. A secondary alcohol, cyclohexanol, was chosen as a model compound for tagging. As illustrated in FIG. 4, fluorous alkoxysilyl ethers (34a,b) were readily prepared by reacting stoichiometric amounts of commercially available dichlorosilanes 32 with fluorous alcohol 22 to yield chlorosilanes 33a,b, which were however contaminated with the bis-adduct of the fluorous alcohol. Without purification, 33a,b were used to protect cyclohexanol as illustrated in FIG. 4 . The ensuing mixture was purified by solid phase extraction on fluorous reverse phase silica gel with hexane/acetone (50:1). The indicated yields were isolated yields after separation from bis-adducts of the fluorous alcohol. Conversion based on cyclohexanol was quantitative.
Alkoxysilyl ether 37a was derived from bromosilane 36, which can easily be obtained in high yield and purity in a two step sequence starting from tert-butyldiphenylsilylchloride (TBDPS-Cl) and alcohol 35 as illustrated in FIG. 4 .
Fluorous alkoxysilyl ethers (34a,b, 37a) were each dissolved in a mixture of CH 2 Cl 2 /trifluoroacetic acid (5%), and aliquots of these solutions were quenched with MeOH/pyridine (20:1). The quenched reaction mixtures were analyzed for remaining 34a,b and 37a by LC-MS (Liquid chromatography-mass spectrometry). Reactions and quenching were performed on a HP 7868 solution phase synthesizer. Analysis of quenched samples was done with a HP 1100 series LC/MS. Samples eluted were compared with unreacted control samples. (R t [min]: 2.6 (34a), 2.9 (34b), 2.3 (37a); Novapak C 18 , 3.9×150 mm, 1.2 mL/min, MeOH as eluent).
The stability of these alkoxysilyl ethers appeared to be determined by the steric bulk around the silicon atom. While 34a was not very stable (t 1/2 ˜6 min) under the acidic reaction conditions, 34b (t 1/2 ˜4 h) was moderately stable, and the tert-butyl-phenyl-1H,1H,2H,2H-heptadecafluorodecyloxysilyl ether 37a (t 1/2 >>6 h) was very stable. These results prompted investigation of the chemical behavior of 37a in somewhat greater detail. As a result of the enhanced electrophilicity of the silicon atom in bis-alkoxysilyl ethers, the latter are generally more labile toward nucleophiles and bases than either the TBDPS or the tert-butyldimethylsilyl (TBDMS) groups. Yet, after dissolving 37a in a mixture of THF-d 8 and 0.25 M NaOD (3:1), a t 1/2 of 48 h was determined by 1 H NMR, suggesting that the tert-butyl-phenyl-1H,1H,2H,2H-hepta-decafluorodecyloxysilyl (BPFOS) tag can be used in mildly basic aqueous media. In contrast, the stability under protic acidic conditions in 5% p-TsOH/MeOH (t 1/2 ˜40 min) is more limited. Based on these results, it appears that the BPFOS group is closely related in stability to the tert-butylmethoxyphenylsilyl group, which is slightly more acid-labile than the TBDPS function but considerably more acid-stable than a TBDMS-ether.
The viability of the tert-butyl-phenyl-1H,1H,2H,2H-heptadecafluorodecyloxysilyl (BPFOS) protecting group for the protection of alcohols in a parallel synthesis experiment performed on a HP 7868 solution phase synthesizer was also studied. Silylbromide 36 was reacted with a panel of alcohols to yield the bis-alkoxysilyl ethers 37a-f as illustrated in FIG. 5 . In general, alcohols 38a-f (0.16 mmol) were added to a solution containing the appropriate amount of reagents in 0.7 mL of CH 2 Cl 2 . The samples were vortexed and left for 16 h. The solutions were washed with H 2 O, the organic phase was evaporated and the residue was eluted with hexane through cartridges containing SiO 2 .
Table 1 summarizes data for the protection of alcohols 38a-f with 36 as set forth in the following equation (and deprotection of silyl ethers with TBAF (tetrabutylammonium fluoride)). [ ] Yields were based on isolated and characterized material ( 1 H NMR, MS) and were slightly lower than reported for the bulk synthesis of 37a as a result of loss of material in the liquid-liquid extraction steps on the synthesizer. Purification in the deprotection step was via FC-72/CH 3 CN liquid-liquid extraction and filtration through silica gel, and provided material of >90% purity. During the deprotection step, silyl ethers 37a-f were added to a solution of TBAF (0.6 M) in 0.5 mL of THF. After 3 hours, Et 2 O was added, the solutions were washed with H 2 O (3 times), the Et 2 O phase was collected, evaporated and the residue was partitioned between FC-72 and CH 3 CN. The organic phase was eluted with hexane/AcOEt through a SiO 2 cartridge.
TABLE 1
Yield for
BPFOS
attachment
Yield for BPFOS
Entry
R—OH
[%]
cleavage [%]
1
79
77
2
77
88
3
24
nd
4
83
94
5
27
nd
6
62
100
Primary and secondary alcohols gave excellent to fair yields in the protection and deprotection steps while, probably for steric reasons, the tertiary alcohol t-butanol (entry 5) and the sterically demanding methyl mandelate (entry 3) provide less favorable yields.
In summary, new acid stable fluorous silane tag suitable for the protection of primary and secondary alcohols have been developed. The tag is easily attached and removed in an automated parallel synthesis setup and allows for purification of intermediates and products via fluorous liquid-liquid or solid phase extraction.
Exemplary Applications
Two model applications serve to illustrate the potential use of the newly developed fluorous tags of the present invention. For example, FIG. 6 illustrates the preparation of aldehyde 39 which is subjected to an in situ obtained mixture of six organolithium reagents. The excess of reagents converts the aldehyde rapidly to adduct 40, which is trapped by addition of AE F vinyl ether tag 23 as illustrated in FIG. 7 . Only the desired secondary alcohol products are rendered fluorous with this approach and converted to acetals 41, which are readily purified by fluorous techniques, or, if required, by chromatography. The stability of the AE F protective group allowed easy manipulation of these products even in an aqueous basic environment, conditions that would lead to immediate decomposition of the earlier silyl ether based tags. After separation from the byproducts and reagents, compounds 41 are de-tagged, and the desired mixture of alcohols 42 is obtained in high yield ready for biological testing. The very high level of combinatorial mixture purification that can be obtained with this approach is demonstrated by the LC-MS trace shown in FIG. 8 .
FIG. 9 illustrates a powerful application for the use of BPFOS tagging compound 36, and demonstrates the first example of a solid phase—fluorous phase switch. Addition of Grignard reagent to the bead-linked aldehyde derived from 49 provides alcohol 50 which is tagged/protected as BPFOS-ether 51 and thus rendered both solid and fluorous. After acidic (TFA) cleavage of the solid support, the BPFOS tagging group allows the extraction of product 52 into the fluorous environment, and subsequent solution phase chemistry can immediately take advantage of fluorous phase purification techniques. No existing fluorous silyl ether tag has the stability necessary to allow this conversion.
Experimental Examples
Compounds 12-20, were obtained in pure form and fully characterized. Cis-11: Mp 66-69° C.; IR (KBr) 3063, 2919, 2853, 1664, 1603, 1445, 1199 cm −1 ; 1 H NMR (CDCl 3 )δ 8.00-7.90 (m, 2H), 7.70-7.55 (m, 3H), 4.87 (d, 1H, J=4.3 Hz), 4.50 (dt, 1H, J=11.5, 3.4 Hz), 3.72-3.66 (m, 1H), 3.17-3.00 (m, 1H), 2.64-2.56 (m, 1H), 2.05-1.75 (m, 4H); 13 C NMR (CDCl 3 )δ 136.5, 134.3, 129.3, 128.9, 125.0-105.0 (m, 8 C), 85.6, 63.3, 32.4 (t, 1 C, J=20.1 Hz), 19.9, 17.5; MS (CI) m/z (rel. intensity) 629 ([M+H] + ).
General Procedure for Glycosylation. A mixture of 200 mg of powdered molecular sieves (4 Å), zirconocene dichloride (139 mg, 0.48 mmol), silver perchlorate (200 mg, 0.96 mmol), and 5 mL of CH 2 Cl 2 was stirred at room temperature for 10 min. Benzyl alcohol (49.0 μL, 0.47 mmol) was added to the yellow solution, and the temperature was lowered to −20° C. A solution of cis-11 (446 mg, 0.71 mmol) in 10 mL of CH 2 Cl 2 was added, and the reaction mixture was allowed to warm gradually to room temperature. After 10 h, the solution was filtered through a pad of SiO 2 . After rinsing with CH 2 Cl 2 , the filtrate was concentrated and the residue partitioned between 4 mL of MeCN and 15 mL of FC-72. The MeCN layer was washed with 4 additional 10-15 mL portions of FC-72. 1 H NMR of the combined fluorous extracts showed the desired product 14 as well as elimination product 4 in a 5.3:1 ratio. 1 H NMR of the MeCN layer showed primarily excess sulfoxide 11. Chromatography of the FC-72 extract on SiO 2 (hexanes/Et 2 O, 97:3) provided pure 14 (264 mg, 0.43 mmol, 92%) as a colorless solid (7.4:1 ratio of diastereomers): Mp 36-37° C.; IR (KBr) 3037, 2966, 2879, 1501, 1450, 1358, 1209, 1147 cm −1 ; Major diastereomer: 1 H NMR δ (CDCl 3 ) 7.37-7.29 (m, 5H), 4.99 (d, 1H, J=3.5 Hz), 4.80 (d, 1H, J=11.6 Hz), 4.54 (d, 1H, J=11.7 Hz), 3.97-3.90 (m, 1H), 3.63 (dt, 1H, J=11.3, 5.0 Hz), 2.60-2.40 (m, 1H), 2.20-2.09 (m, 1H), 1.90-1.80 (m, 2H), 1.60-1.50 (m, 1H); 13 C NMR δ (CDCl 3 ) 137.4, 128.5, 128.0, 125.0-105.0 (m, 8 C), 95.2, 69.6, 61.0, 41.3 (t, 1 C, J=19.5 Hz), 21.9, 18.7, 17.4; HRMS (EI) calculated for C 20 H 15 O 2 F 17 610.0801, found 610.0803.
General Procedure for Deprotection of ROTHP F -tagged compounds. A solution of 14 (112 mg, 0.18 mmol) and p-toluenesulfonic acid (9 mg, 0.05 mmol) in 2 mL of MeOH and 2 mL of THF was heated at 70° C. for 24 h. The reaction mixture was diluted with Et 2 O and washed with a saturated NaHCO 3 solution. The organic layer was dried (Na 2 SO 4 ), concentrated, and partitioned between 2 mL of MeCN and 8 mL of FC-72. The MeCN layer was washed with three 8 mL portions of FC-72. 1 H NMR analysis of the combined FC-72 extracts showed 9 (82 mg, 0.15 mmol, 84%) with a trace amount of 4. 1 H NMR analysis of the MeCN layer showed pure benzyl alcohol (19.0 mg, 0.176 mmol, 96%).
Preparation of 22: A suspension of 4.2 g (0.173 mmol) of Mg powder and 2.5 g (4.36 mmol) of iodide 21 in 20 mL of Et 2 O was sonicated for 20 min. To this black mixture was added dropwise a solution of 22.5 g (39.2 mmol) of iodide 21 in 150 mL of Et 2 O. The reaction mixture was heated at reflux for 2 h, and the solution was cannulated away from the excess Mg into a new flask. After dropwise addition of 1.40 mL (17.4 mmol) of ethyl formate, the black solution was heated at reflux for 5 h. The reaction mixture was cooled to 0° C., quenched with saturated ammonium chloride solution and extracted with Et 2 O. The organic extracts were dried (Na 2 SO 4 ) and concentrated. The crude product was washed with CH 2 Cl 2 and dried in vacuo to give 14.92 g (16.15 mmol, 93%) of 22 as a white solid: Mp 98-101° C.; IR (KBr) 3461, 1204, 1146 cm −1 ; 1 H NMR (CDCl 3 )δ 4.20 (d, 1H, J=6.0 Hz), 3.80-3.73 (m, 1H), 2.60-2.15 (m, 4H), 1.95-1.65 (m, 4H); 13 C NMR (TFA)δ 125.0-105.0 (m, 16 C), 79.4, 28.4, 25.9; MS (EI) m/z (rel. intensity) 907 ([M-OH] + , 2), 887 (6), 477 (100).
Preparation of 23: A mixture of 14.92 g (16.15 mmol) of 22, 2.6 g (8.1 mmol) of Hg(OAc) 2 , 100 mL of ethyl vinyl ether, and 100 mL of FC-72 (commercially available from 3M) was heated at reflux for 40 h. After cooling to room temperature, the reaction mixture was transferred to a separatory funnel, and the layers were separated. The organic layer was extracted with FC-72 (3×), and the combined FC-72 extracts were dried (Na 2 SO 4 ), and concentrated. The crude product was loaded onto a short (1.5″) pad of SiO 2 and washed with hexanes until no more 23 was shown to be eluting via TLC. The hexane washings were concentrated to give 7.85 g (8.2 mmol, 51%) of 23 as a white solid, Mp 36-38° C. Flushing the SiO 2 pad with EtOAc, followed by concentration of the filtrate gave 6.29 g (6.8 mmol, 42%) of 22. Spectroscopic data for 23: IR (KBr) 3131, 1646, 1617, 1209, 1151 cm −1 ; 1 H NMR (CDCl 3 )δ 6.27 (q, 1H, J=6.6 Hz), 4.35 (d, 1H, J=14.2 Hz), 4.10 (d, 1H, J=6.5 Hz), 3.91 (p, 1H, J=5.5 Hz), 2.35-2.00 (m, 4H), 1.95-1.75 (m, 4H); 13 C NMR (CDCl 3 )δ 150.0, 125.0-105.0 (m, 16 C), 89.8, 76.4, 26.7 (t, J=22.1 Hz), 24.8; MS (EI) m/z (rel. intensity) 950 (M + , 7), 887 (20), 391 (100).
Protection of cinnamyl alcohol: To a solution of 10.5 mg (0.08 mmol) of cinnamyl alcohol and 223 mg (0.24 mmol) of 23 in 3 mL of Et 2 O was added 1 mg (5 mol %) of 10-camphersulfonic acid (CSA). The solution was stirred at room temperature for 3 h. Saturated NaHCO 3 solution was added, and the reaction mixture was extracted with FC-72 (3×). The combined FC-72 extracts were dried (Na 2 SO 4 ), and concentrated. Column chromatography on SiO 2 (hexanes/Et 2 O, 95:5) gave 101 mg (0.11 mmol, 64%) of 23 and 79 mg (0.073 mmol, 93%) of the desired AE F -protected cinnamyl alcohol as a colorless oil: IR (neat) 3032, 2981, 1491, 1204, 1148, 907 cm −1 ; 1 H NMR (CDCl 3 )δ 7.38-7.21 (m, 5H), 6.60 (d, 1H, J=15.9 Hz), 6.25 (dt, 1H, J=5.9, 15.9 Hz), 4.81 (q, 1H, J=5.3 Hz), 4.26-4.13 (m, 2H), 3.80 (p, 1H, J=5.5 Hz), 2.40-2.00 (m, 4H), 1.90-1.75 (m, 4H), 1.37 (d, 3H, J=5.2 Hz); 13 C NMR (CDCl 3 )δ 136.6, 132.4, 128.7, 127.9, 126.5, 125.4, 125.0-105.0 (m, 16 C), 99.0, 73.4, 65.8, 26.4, 20.4; MS (EI) m/z (rel. intensity) 951 ([M-OCH 2 CHCHPh] + , 9), 887 (9), 577 (8), 477 (50), 118 (100).
Deprotection of AE F -protected cinnamyl alcohol: A solution of 71 mg (0.065 mmol) of AE F -OCH 2 CH═CH-Ph and 1 mg (5 mol %) of CSA in 1 mL of MeOH and 1 mL of Et 2 O was stirred at room temperature for 1 h. The reaction mixture was then transferred to a separatory funnel, and saturated NaHCO 3 solution and FC-72 were added. The organic and aqueous layers were washed with FC-72 (3×). The combined FC-72 extracts were dried (Na 2 SO 4 ), and concentrated to give 60 mg (100%) of 22. The organic layer was dried (Na 2 SO 4 ), and concentrated to give 8.6 mg (98%) of cinnamyl alcohol.
Preparation of 34b: A solution of dichlorodiphenylsilane (0.7 mmol), alcohol 22 (0.7 mmol) and triethylamine (0.77 mmol) in a mixture of CH 2 Cl 2 (2.5 mL) and benzotrifluoride (BTF, 2.5 mL) was heated at reflux for 1.5 d. Solvents were evaporated and the residue was partitioned between FC-72 and CH 2 Cl 2 . The FC-72 phases were combined and evaporated. The residue was dissolved in CH 2 Cl 2 (5 mL). Cyclohexanol (0.47 mmol), triethylamine (0.65 mmol) and dimethylaminopyridine (DMAP, 0.02 mmol) were added and the mixture was stirred at room temperature overnight. 3-Phase extraction (NaHCO 3 solution, CH 2 Cl 2 , FC-72) yielded after pooling and evaporation of the FC-72 phase a colorless oil. Filtration over fluorous reverse phase silica (hexane/acetone 50:1) gave 0.24 g (47%) of 34b as a colorless oil which solidified upon standing: 1 H NMR (CDCl 3 )δ 7.62-7.59 (m, 4H), 7.45-7.35 (m, 6H), 3.98-3.92 (m, 1H), 3.82-3.73 (m, 1H), 2.3-1.9 (m, 4H), 1.9-1.6 (m, 8H), 1.5-1.3 (m, 3H), 1.2-1.0 (m, 1H); 13 C NMR (CDCl 3 )δ 134.9, 132.8, 130.5, 128.0, 125-105 (m, 16C), 71.8, 70.6, 35.5, 27.4, 27.2 (b), 25.4, 23.9; MS(EI) m/z (rel. intensity) 1204 (M + , 4), 1185 (5), 1126 (85).
Preparation of 37a: A solution of TBDPS-CL (26.5 mmol), alcohol 35 (24.1 mmol), DMAP (1.2 mmol) and imidazole (33.8 mmol) in CH 2 Cl 2 (50 mL) was stirred at room temperature overnight. CH 2 Cl 2 was added and the solution was washed with H 2 O, 1 M HCl and brine. Drying (Na 2 SO 4 ) and evaporation of the solvent yielded the TBDPS ether as a colorless oil: 15.5 g (92%) 1 H NMR (CDCl 3 )δ 7.69-7.66 (m, 4 H), 7.45-7.38 (m, 6H), 3.96 (t, 2H), 2.45-2.25 (m, 2H), 1.07 (s, 9H); 13 C NMR (CDCl 3 )δ 135.2, 134.9, 129.9, 127.9, 125-105 (m, 8C), 56.3, 33.9 (b), 26.6, 19.1.
Bromine (26.5 mmol) was added dropwise to a solution of the TBDPS et her (22.1 mmol) in 1,2-dichloroethane (150 mL) at 0° C. Stirring continued at room temperature overnight. Distillation (0.03 mbar/105-110° C.) yielded 11.3 g (72%) of 36 as a colorless oil: 1 H NMR (CDCl 3 )δ 7.69-7.65 (m, 2 H), 7.48-7.39 (m, 3H), 4.11-4.06 (m, 2H), 2.47-2.35 (m, 2H), 1.01 (s, 9H); 13 C NMR (CDCl 3 )δ 135.6, 134.9, 131.1, 128.1, 125-105 (m, 8C), 57.0, 34.0 (b), 25.1, 21.4.
36 (1.1 mmol) was dissolved in CH 2 Cl 2 (5 mL). Cyclohexanol (1 mmol), triethylamine (1.4 mmol) and dimethylaminopyridine (DMAP, 0.05 mmol) were added and the mixture was stirred at room temperature overnight. CH 2 Cl 2 was added and the mixture was washed with NaHCO 3 solution. The organic phase was dried (Na 2 SO 4 ), the solvent was removed and the residue filtered through SiO 2 (hexane/EtOAc 98:2) to give 0.70 g (97%) of 37a as a colorless oil: 1 H NMR (CDCl 3 )δ 7.65-7.60 (m, 2H), 7.42-7.35 (m, 3H), 4.11 (t, 2H, J=6.9 Hz), 3.95-3.88 (m, 1H), 2.50-2.35 (m, 2H), 1.84-1.72 (m, 4H), 1.52-1.40 (m, 3H), 1.30-1.21 (m, 3H), 0.94 (s, 9H); 13 C NMR (CDCl 3 )δ 135.5, 132.3, 129.9, 127.8, 125-105 (m, 8C), 71.1, 55.7, 35.7, 34.1 (b), 26.1, 25.6, 23.7, 18.8; HR-MS(EI) m/z found 723.1597, calcd 723.1587.
Reactions and quenching were performed on a HP 7868 solution phase synthesizer. Analysis of quenched samples was done with a HP 1100 series LC/MS. Samples eluted were compared with unreacted control samples. (R t [min]: 2.6 (34a), 2.9 (34b), 2.3 (37a); Novapak C 18 , 3.9×150 mm, 1.2 mL/min, MeOH as eluent).
Protection of alcohols 38a-f. Alcohols 38a-f (0.16 mmol) were added to a solution containing the appropriate amount of reagents in 0.7 mL of CH 2 Cl 2 . The samples were vortexed and left for 16 h. The solutions were washed with H 2 O, the organic phase was evaporated and the residue was eluted with hexane through cartridges containing SiO 2 .
Deprotection of ethers 37a-f. Silyl ethers 37a-f were added to a solution of TBAF (0.6 M) in 0.5 mL of THF. After 3 h, Et 2 O was added, the solutions were washed with H 2 O (3 times), the Et 2 O phase was collected, evaporated and the residue was partitioned between FC-72 and CH 3 CN. The organic phase was eluted with hexane/AcOEt through a SiO 2 cartridge.
Although the present invention has been described in detail in connection with the above examples, it is to be understood that such detail is solely for that purpose and that variations can be made by those skilled in the art without departing from the spirit of the invention except as it may be limited by the following claims.
|
A method of increasing the fluorous nature of a compound includes the step of reacting the compound with at least one second compound having the formula:
wherein Rf is a fluorous group and m is 0, 1 or 2.
| 2
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This application is a Continuation of application Ser. No. 07/925,661, filed on Aug. 07, 1992, now abandoned.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a system of a microprocessor suitable for simultaneously executing a plurality of independent programs.
2. Description of the Related Art
As an operation system of the microprocessor suitable for simultaneously executing a plurality of independent programs, an interruption system, a time slice system, and a multiprocessor system have been conventionally used.
The interruption system can be explained as follows.
If a specific interruption signal is generated while a program of a computer is executed, the program that is being executed is suspended and the program is branched to another routine for processing the specific program in which the interruption is received. After the program is executed, the program is returned to the original routine, and the operation of the original program is started again.
The time slice system can be explained as follows:
A plurality of programs are processed in the predetermined order of their priority at a constant time, that is, using time for CPU which a scheduler assigns to the program.
The multiprocessor system can be explained as follows:
A plurality of CPUs are provided and a plurality of programs are processed in parallel, in order to realize the computer system having high performance, which is excellent in high speed, reliability, and expandability.
However, in the microprocessor of the interruption processing system, the following problem exists.
While the program is branching to another routine for processing the specific program, other programs must be interrupted. Due to this, loss time is generated, and execution speed of the microprocessor is reduced.
In the microprocessor of the time slicing system, the following problem exists.
Since using time for a CPU, which a scheduler assigns to the program, is roughly sliced (ms unit), time restriction must be received.
In the microprocessor of the multiprocessor system, the following problem exists.
Since a plurality of CPUs of parallel processing type are needed, the manufacturing cost increases, the management of the CPUs are complicated, and the efficiency of CPUs are generally decreased.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a microprocessor which can simultaneously process a plurality of programs in a relatively short period of time.
More specifically, there is provided a microprocessor processing for data corresponding to a plurality of computer programs comprising a plurality of program counters for pointing out an address to be presently processed in one of the programs, means for selecting one of the program counters wherein the selecting means has a plurality of independent storing means for storing an arbitrary selection order of the program counters, an arithmetic logic unit for processing data in accordance with the program of the address pointed out by one of the program counters selected by the selecting means, and means for transferring data between the program counters, the selecting means, and the arithmetic logic unit.
According to the above structure, the address corresponding to the computer program counters is designated to the plurality of programs. Further, the selecting means shows the selection order of the plurality of program counters, thereby the arithmetic logic unit processes the plurality of programs alternately. That is, the plurality of programs can be controlled in a time-sharing manner. Moreover, the arbitrary selection order of the plurality of programs can be set depending on how the selection order is stored in the storing means in the selecting means. Thereby, various time sharing programs can be processed.
Furthermore, the plurality of storing means independently operate, and the specific storing means is selected, so that the predetermined selection order can be instantaneously set, and parallel time sharing process of various plurality of programs can be executed.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention.
FIG. 1A is a block diagram showing a microprocessor of an embodiment of the present invention;
FIG. 1B is a block diagram showing a specific embodiment of a PC block 15 shown in FIG. 1A and a scheduler block 16;
FIG. 2 is a view showing a relation between the order of the program counter selected by the scheduler of the present invention and data outputted based on the program counter; and
FIGS. 3A, 3B, and 3C are tables showing the program counter designated by each scheduler of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The microprocessor of the present invention will be explained with reference to the drawings.
The microprocessor of the present invention is similar to a microprocessor having four CPUs from a functional viewpoint. From a structural view point, the microprocessor of the present invention has one CPU, but the CPU executes a plurality of programs alternately in a time sharing manner. Thereby, the processor of the present invention can control a plurality of objects in real time.
The structure of a microprocessor 10 shown in FIGS. 1A and 1B will be explained.
FIG. 1A is a block diagram showing a microprocessor according to the embodiment of the present invention. FIG. 1B is a block diagram showing a specific embodiment of a PC block 15 shown in FIG. 1A and a scheduler block 16. In this case, the microprocessor 10 of FIG. 1A is provided in one silicon chip. Moreover, the microprocessor 10 comprises an I/O unit 11, a ROM 11, a RAM 13, an ALU 14 (Arithmetic Logical Unit), the PC (Program Counter) 15 and the scheduler (hereinafter called "SCHD") block 16. Moreover, there is a case that the microprocessor also comprises an EEPROM 19 holding the storing content of the SCHD 16 and appropriately changing the storing content.
These I/O unit 11, ROM 11, RAM 13, ALU 14 (Arithmetic Logical Unit), PC (Program Counter) block 15 and the SCHD block 16 are connected to a bus line 17. Moreover, ROM 12, RAM 13, and ALU 14 are connected to one another, ALU 14 and PC block 15 are connected to each other, and PC block 15 and SCHD block 16 are connected to each other.
ALU 14 and PC block 15 constitute a CPU 18. As shown in FIG. 1B, the PC block 15 has a PC selector 5 and a PC group 6. The PC group 6 comprises four PCs, that is, PC0, PC1, PC2, and PC3. However, the present invention can be attained if two or more PCs are provided. Each of PCs (PC0, PC1, PC2, PC3) serves as a dedicated register for holding an address of a command of a program to be executed next.
The PC selector 5 is used to select the PCs (PC0, PC1, PC2, PC3).
The SCHD block 16 comprises a SCHD setting section 1, a SCHD selecting section 3, a SCHD register file section 2 for data setting of SCHD (2 bits×8×4 blocks), a SCHD counter section 4, a column designation unit 21, a sense amplifier 22, and row designation unit 23.
The SCHD register file section 2 comprises four SCHDs (SCHD1, SCHD2, SCHD3, SCHD4), and is used to set the operation order of the PC group 6. The SCHD register file section 2 uses a maximum of four blocks (SCHD1 to SCHD4). Also, only one block can be used.
The SCHD setting section 1 sets data of the operation order of the PC (PC0 to PC3) in each of SCHDs 1 to 4 of the SCHD register file section 2.
The SCHD selecting section 3 is divided into a row selector and a column selector, and outputs a 2-bit data signal to a PC selector 5 via a data line D2. The SCHD selecting section 3 selects data set in each SCHD (SCHD1 to SCHD4) of the SCHD register file section 2.
The SCHD counter 4 supplies a 3-bit data signal to the SCHD selecting section 3 via a data line D1.
The I/O unit 11 is an I/O interface inputting/outputting data.
An operation of the microprocessor 10 to operate the PC of the above-mentioned embodiment will be explained with reference to drawings.
FIG. 2 is a view showing an execution order of the PC in the microprocessor. In this drawing, a section a is a view showing which program counter is selected by SCHD when the microprocessor is turned on. For example, "PC3" shows that the program counter 3 is selected. A section b is a view showing a part of the operation order of PC shown in FIG. 2, and a section c is a view showing a 2-bit signal to be outputted to the SCHD selecting section 3 from the SCHD counter 4. For example, 2-bit signal "11" shows PC3 and 2-bit signal "00" shows PC0. A section d is a view showing a signal to be outputted to the SCHD selecting section 3 from the SCHD counter. For example, 0 shows a first register in the SCHD.
FIG. 3A shows a data table showing an example of an execution of PC, which each scheduler selects. For example, SCHD1 of FIG. 3A shows data set in eight registers provided in SCHD1. A first 2-bit signal "3" of SCHD2 shows PC3 set in the first register, and a 3-bit signal "2" shows PC2 set in the second register. In this drawing, SCHD 1 shows that PC0 is continuously designated. In a case where a program to be processed is one, there is considered that one program is continued to be designated and processed by PC0.
FIGS. 3B and 3C show examples of the other data of the scheduler. FIG. 3B shows the case in which all data of scheduler are set to "0" (zero) by an external terminal or a special command, and PC0 is always selected. FIG. 3C shows the case that SCHD1 to SCHD4 correspond to PC0 to PC3, respectively, and one type of program is continued to be selected so as to continue designating one type of PC. In these examples, data is reserved in EEPROM 19 of FIG. 1, and data is moved to SCHD 16 as required, so that the operation can immediately correspond to one using state of one program counter.
The operation of the microprocessor 10 relating to the contents of SCHD1 to SCHD4 will be explained.
First, data is transmitted to the SCHD setting section 1 via a bus line 17 on the program. The SCHD setting section 1 receives data from the bus line 17, and sets the execution order of the PC (PC0 to PC3) to the SCHD (SCHD1 to SCHD4) as shown in FIG. 3.
More specifically, the SCHD setting section 1 sets data shown in SCHD 1 of FIG. 3, and sets the operation order of PC (PC0 to PC3) shown in SCHD2 of FIG. 3. Moreover, the SCHD setting section 1 sets the operation order of PC (PC0 to PC3) shown in SCHD3 of FIG. 3, and sets the operation order of PC (PC0 to PC3) shown in SCHD4 of FIG. 3.
On the other hand, data instructing which scheduler should be selected is sent to the SCHD selecting section 3 from a data line (not shown). In accordance with the command, the SCHD selecting section 3 selects, for example, SCHD 2. If the operation order of PC (PC0 to PC3) is set by the SCHD setting section 1, it is further set which scheduler should be selected. Then, a 3-bit select signal D1 is transmitted to the SCHD selecting section 3 from the SCHD counter 4. Due to this, SCHD selecting section 3 selects any one of eight data set in the selected SCHD in order.
For example, if the SCHD2 is selected, the SCHD2 of FIG. 3, that is, a series of program counters shown in the section b of FIG. 2, is selected in order.
The SCHD selecting section 3 outputs a 2-bit data signal of data shown in the selected section c of FIG. 2 to the PC selector 5.
The PC selector 5 receives the data signal from the SCHD selecting section 3, and selects the PC in the order of PC3, PC3, PC3, PC1, PC3, . . . as shown in the SCHD2 of the section a of FIG. 2. If the PC selection is performed up to PC0 as shown in the section a, the PC selection is repeated from the PC3.
By the above-mentioned operation, the program is executed in accordance with the address held in the PC in the operation order shown in the section a. In a case where SCHD1 is set, only program counter PC0 is executed, and other PCs (SCHD1 to SCHD3) are not executed.
Moreover, if a reset signal RSET shown in FIG. 1B is inputted from an external terminal 20, each bit of the scheduler 2 is all reset to "0." The reset signal is also sent to a program counter 15 via a reset unit 24.
Regarding the state of these signals, as shown in an INITIAL section of the section a of FIG. 2, the PC0 is automatically continued to be designated until the signal which the scheduler designates is generated at the time of turning on the power supply.
Finally, if the microprocessor 10 of FIG. 1A receives a command of the end of the operation via the bus line 17, the operation is ended.
An execution speed of the program to be executed in accordance with the address held in each PC will be explained with reference to the drawings.
For example, in a case where the execution order of PC is set in the SCHD2 as shown in the section a of FIG. 2, the execution speed of the program in accordance with each PC will be explained as follows.
That is, as shown in FIG. 2, it is assumed that using time for the CPU to be assigned to one command is 1 μs. In accordance with the execution of one command, PC is executed eight times. Therefore, one operation time of PC can be obtained by 1/8 μs, and T1 is 0. 125 μs. Therefore, in the case where the operation order of the PC is set as shown in the section b of FIG. 2, PC0 and PC1 are executed once in accordance with one command, so that using time for CPU to be assigned to the PC0 is 0.125 μs, and its using speed is 1.000 μs/INST.
Since PC2 is executed twice, using time for CPU to be assigned to the PC2 is 0.25 μs, and its using speed can be obtained by 1/2, that is, the using speed is 0.500 μs/INST.
Since PC3 is executed four times, using time for CPU to be assigned to the PC3 is 0.5 μs, and its using speed can be obtained by 1/4, that is, the using speed is 0.250 μs/INST.
PC0, PC1, PC2, PC3, . . . PC0 shown in the section a of FIG. 2 means that each PC is arranged in the execution order.
PC3, PC2, PC3, . . . PC0 shown in the section b of FIG. 2 shows a part of PC shown in the section a of FIG. 2. Moreover, signals D1 "11, 10, 11, . . . 00" sent from the SCHD counter 4 is that "3, 2, 3, . . . 0" are shown by 2-bit signal so as to correspond to PC3, PC2, PC3, . . . PC0.
Furthermore, 0 to 7 of the section d of FIG. 2 means 3-bit signal D1 to be supplied to the PC selector 4 from the SCHD selecting section 3.
And as other embodiment, many external terminals (FIGS. 1B, 31, 32) of the microprocessor is formed and a user can supply specific, for example, two bits signals (meaning of SCHD 1:00) via to the terminals. Accordingly, the processor selects the specific scheduler 1 by the specific signals regardless of program contents of that time. Thereby, a user can select the desire scheduler all the time via to the terminals. And in FIG. 1B, the signal from the terminals works the Row selector 3 and 23 and the specific scheduler is selected forcely.
According to the above-structured microprocessor, a user can set a processing interval (time) of a plurality of programs to the SCHD register file section 2 by one command unit.
The CPU is used at above-explained using time and using speed. Then, the PC is repeatedly operated in the arrangement order set in the register, thereby each PC is executed every constant time fixed by data set in the SCHD.
Therefore, the program can be processed at high speed as required. Moreover, since the processing time can be distributed so as to correspond to each program, efficiency of the system can be improved.
Additionally, data setting of the SCHD of the register file section 2 to be selected (2 bits×8) can be changed by the command during the execution of the program as required. Thereby, the execution order of the program can be changed during the execution of the program as required.
The present invention is not limited to the abovementioned embodiment. The present invention can be variously modified.
For example, in the above embodiment, four SCHDs are provided. However, the present invention can be attained if two or more SCHDs are provided.
Moreover, in the above embodiment, four PCs are provided. However, the present invention can be attained if two or more PCs are provided.
For example, the SCHD setting section 1 freely rewrites SCHD1, SCHD3, and SCHD4 in accordance with the command from the bus line 17 in selecting the SCHD2. Moreover, the SCHD selecting section 3 freely selects the SCHD in accordance with the command, and, for example, SCHD2 is changed to SCHD3. Thereby, the selection order of the program counter PC is changed during the execution of the program.
Moreover, the content itself during the selection of the program counter PC may be rewritten.
According to the above-explained structure, even in the microprocessor having one CPU, the user can set the processing time of the plurality of programs by one command unit. As a result, the program can be processed at high speed as required. Moreover, the processing time can be distributed so as to correspond to each program, and efficiency of the entire system can be improved.
Moreover, the processing time of the programs can be clarified, and real time (parallel) processing of the microprocessor can be easily designed.
Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, and representative devices shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
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A microprocessor for processing data corresponding to a plurality of computer programs includes multiple program counters each specifying a program address of a computer program having data to be processed, a selector for sequentially selecting the program counters, the selector having multiple independent storage sections for storing a plurality of arbitrary selection order of the program counters, an arithmetic logic unit for processing data of the computer program corresponding to the program address stored in one of the program counters selected by the selector, and a device for transferring data between the program counters, the selector, and the arithmetic logic unit.
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CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY CLAIM
This application is a continuation of U.S. Non-Provisional application Ser. No. 12/821,726, entitled “PERFORMANCE OPTIMIZATION AND DYNAMIC RESOURCE RESERVATION FOR GUARANTEED COHERENCY UPDATES IN A MULTI-LEVEL CACHE HIERARCHY”, filed Jun. 23, 2010, which is incorporated herein by reference in its entirety.
BACKGROUND
This invention relates generally to processing within a computing environment, and more particularly to computing systems having a multilevel cache hierarchy.
In computers, a cache is a component that improves performance by transparently storing data such that future requests for that data can be served faster. The data that is stored within a cache might be values that have been computed earlier or duplicates of original values that are stored elsewhere (e.g. main memory). If requested data is contained in the cache (cache hit), this request can be served by simply reading the cache, which is comparably faster. Otherwise (cache miss), the data has to be recomputed or fetched from its original storage location, which is comparably slower.
Cache operations in a shared cache may be performed by accessing a shared pipeline. A pipeline may be considered as a set of data processing elements connected in series, so that the output of one element is the input of the next one. An instruction pipeline may be used in a computing device to increase instruction throughput (the number of instructions that can be executed in a unit of time). The fundamental idea is to split the processing of a computer instruction into a series of independent steps, with storage at the end of each step. This allows the computer's control circuitry to issue instructions at the processing rate of the slowest step, which is much faster than the time needed to perform all steps at once. The term pipeline refers to the fact that each step is carrying data at once (like water), and each step is connected to the next (like the links of a pipe.)
In prior art systems that included multi-level caches, the highest level of the cache hierarchy served as both the point of coherency for the system and the source of data to be provided to lower level caches.
BRIEF SUMMARY
An embodiment of the present invention is directed to is a cache that includes a cache pipeline, a request receiver configured to receive off chip coherency requests from an off chip cache and a plurality of state machines coupled to the request receiver. The cache of this embodiment also includes an arbiter coupled between the plurality of state machines and the cache pipe line that is configured to give priority to off chip coherency requests and a counter configured to count the number of coherency requests sent from the cache pipeline to a lower level cache. In this embodiment, the cache pipeline is halted from sending coherency requests when the counter exceeds a predetermined limit.
According to another embodiment, a memory system is disclosed. The memory system of this embodiment includes an off chip cache configured to source a cache line to a requester without checking the update status of the cache line and to create an off chip coherency request. The memory system of this embodiment also includes a shared cache coupled to the off chip cache and configured to receive the off chip coherency request and to ensure that an instruction to invalidate the cache line is received by a lower level cache before the cache line is sourced.
Additional features and advantages are realized through the techniques of the present invention. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention. For a better understanding of the invention with advantages and features, refer to the description and to the drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
Referring now to the drawings wherein like elements are numbered alike in the several FIGURES:
FIG. 1 depicts an example of system on which embodiments of the present invention may be implemented;
FIG. 2 depicts an alternative embodiment of a system on which embodiments of the present invention may be implemented;
FIG. 3 depicts shared cache coupled to a lower level cache according to one embodiment; and
FIG. 4 is a flow chart showing a method of dynamically balancing resource reservations.
DETAILED DESCRIPTION
FIG. 1 illustrates an example of a computing system 100 according to one embodiment. The system includes one or more nodes 102 . In one embodiment, the system 100 may include four nodes 102 . In a computing system, multiple nodes 102 may be operatively connected to one another for communicating such as making and responding to requests, as understood by one skilled in the art.
Each node 102 includes one or more central processors 102 . In one embodiment, each node 102 includes six central processors 105 . The central processors 105 include one or more cores 130 that perform the reading and executing of instructions. In one embodiment, one or more of the central processors 105 include four cores 130 . Of course, the central processors 105 could include any number of cores 130 that is greater than or equal to two.
Each core 130 is operatively coupled to its own L1 and L2 cache, 107 and 109 respectively. The L1 caches 107 are physically closest to the cores 130 and the L2 caches 109 are coupled to the L1 caches 107 . Each L2 cache 109 in each central processor 105 is coupled to a single L3 cache 111 . In this manner, the L3 cache 111 is shared by multiple L2 caches 107 .
The node 102 also includes one or more L4 caches 110 . The L4 caches 110 are operatively coupled to two or central processors 105 . In this manner, the L4 caches 110 are shared by multiple L3 caches 111 . The system 100 may also include main memory 150 operatively coupled to the L4 caches 110 .
In one embodiment, the L3 caches 111 and L4 cache 110 are formed of embedded dynamic random access memory (DRAM) which is referred to as eDRAM. Of course, it is understood by a skilled artisan that any other types of suitable memory such as DRAM may be utilized. In one embodiment, the L2 caches 109 may be formed of static random access memory (SRAM).
In one embodiment, each individual central processor 105 is fabricated on its own separate chip, which includes the L1, L2, and L3 caches, and the L4 cache 110 is fabricated on its own separate chip. As understood by a skilled artisan, fabrication of chips including integrated circuits, wires, metal layers, semiconductor (and/or other material) components, etc., may be formed via lithography and other techniques. The fabrication process may include various deposition techniques including physical vapor deposition (PVD), chemical vapor deposition (CVD), electrochemical deposition (ECD), molecular beam epitaxy (MBE), and atomic layer deposition (ALD) among others.
In an exemplary embodiment, the L1 caches 107 are between 96 and 128 KB, the L2 caches 109 are 1.5 MB, the L3 cache 111 is 24 MB and the L4 cache 110 is 192 MB. Of course other sizes could be utilized. In FIG. 1 , the four different levels of caches (L1, L2, L3 and L4) are shown. Of course, such an organization of caches is exemplary only and the teachings herein may be applied to any situation where multiple requesters have access to a shared cache and the shared cache is one of a plurality of shared caches that have access to another shared cache.
The L3 cache 111 is a departure from prior schemes in that it introduces a shared cache between the L2 109 and L4 110 caches. That is, in the prior art, the L2 caches 109 were coupled directly to the L4 cache 110 . Accordingly, in the prior art, the L4 cache 110 was both the point of coherency for the node 102 and the source of its data.
In one embodiment, the L2 cache 109 is a write-through cache. Thus, any change in the L2 cache 109 is immediately updated in the L3 cache 111 . The L3 cache 111 , on the other hand, is a write back cache. Thus, changes in the L3 cache 111 are not updated to the L4 cache until requested by the L4 cache 110 (e.g., the L4 cache 110 requests that the L3 cache 111 invalidate a line) or the L3 cache 111 is changed such that the line is invalidated (e.g., the L3 cache 111 swaps out the line).
Given that the L3 cache 111 is a write back cache and may source data to L2 caches 109 , there are instances where the L4 cache 110 may not include the most up to date data contained in the L3 cache 111 . In such instances, to maintain coherency, in the event that the L4 cache 110 receives an access request for data on a particular cache line (or a portion thereof) from main memory 150 it must first query the L3 cache 111 to determine if it has an updated copy of the data and send coherency updates to the lower level caches if the L4 cache 110 requires the L3 cache 111 to change its state with respect to cache line. These requirements may add latency to all requests to the L4 cache 110 , which now must go through the extra step of communicating with the L3 cache 111 before responding to a request.
FIG. 2 illustrates an alternative embodiment of a node 200 . In this embodiment, the node 200 includes one or more central processors 202 a . . . 202 b . Each central processor 202 includes a shared cache 208 that includes a shared cache controller 209 . The node also includes a shared memory 210 that may be accessed by each of the shared caches 208 .
In general, the shared caches 208 receive requests for information (including both data and instruction requests) and if the requested data is contained in the shared caches 208 (cache hit), this request can be served by simply reading the shared cache 208 . Otherwise, a cache miss occurs and the data is requested from shared memory 210 . The determination of whether a cache hit or miss exists and the general operation of the shared cache 208 is controller by the shared cache controller 209 . Of course, any of the caches described herein may include a cache controller.
In one embodiment, the shared cache controller 209 is implemented to include a pipeline and other elements. The shared cache controller 209 may also be responsible for coherency checking. In one embodiment, the shared caches 208 are write back caches.
In more detail, each shared cache 208 is coupled to two or more requesters. For example, shared cache 208 a is coupled to requesters 204 a . . . 204 n and to shared memory 210 , all of which may issue requests to the shared cache 208 a . For example, shared memory 210 or requestors 204 a . . . 204 n may request a copy of a particular cache line contained in shared cache 208 a . In one embodiment, the requestors 204 a . . . 204 n are caches. However, the requestors may include other types of device. For example, requestor 206 a . . . 206 n are coupled to shared cache 208 b in central processor 202 b . In one embodiment, requestor 206 a is an I/O device controller and is coupled to an I/O device 212 . The I/O device 212 may be located on a separate chip than central processor 202 b . Of course, some I/O devices may include internal drivers and may be directly coupled to the shared cache 208 b . One or ordinary skill will realize that other embodiments where a shared cache 208 is coupled to a shared memory 210 and to two or more other requestors, regardless of whether the other requestors are on the same chip as the shared cache, are within the scope of the present invention.
As described above, the on-chip shared cache 208 is a departure from prior schemes in that it introduces a shared cache between the requestors ( 204 , 206 ) and the shared memory 210 . It shall be understood that shared memory 210 may be coupled to main memory 150 ( FIG. 1 ). In one embodiment, the shared cache 208 is a write back cache. Thus, in some embodiments, the shared cache 208 may serve as the source of data and that data may be different than data stored in main shared memory 210 . As described above, in the event that the shared memory 210 receives an access request for data on a particular cache line (or a portion thereof) from main memory 150 ( FIG. 1 ) it must first query the shared cache 208 to determine if it has an updated copy of the data and also to send it coherency updates if the shared memory 210 requires the shared cache 208 to change its state with respect to a cache line. These requirements may add latency to all requests to the shared memory 210 which now must go through the extra step of communicating with the shared cache 208 before responding to a request.
In some cases, the shared memory 210 knows that the shared cache 208 does not have a more up to date copy of the data, so the data can be sourced directly from the shared memory 210 . These cases include where the shared memory 210 wants to convert a shared read only line to an exclusive line. However, the shared memory 210 needs to ensure that the shared cache 208 and any requestor coupled thereto (e.g., any lower level cache) are notified to invalidate its copy of the cache line before it can source the data to the requester. This requirement means that the shared memory 210 cannot return data until it knows that the shared cache 208 has sent a command (e.g. coherency checks) to any lower level cache to ensure that lower level cache invalidates its copy of the data. If the shared cache 208 can guarantee the processing of the coherency updates from the shared memory 210 in these cases, then it is not necessary for the shared memory 210 to wait for the shared cache 208 to indicate that is has removed its data before returning data to the requestor which reduces the time to process a request. Embodiments of the present invention are directed to ensuring that such assurances can be made.
In more detail, requests to the shared memory 210 may request exclusive access to a line or read-only access to the line. Embodiments of the present invention are directed to cases where the request to a shared memory 210 include a request for the data and that the cache line be made converted from a shared read only line to an exclusive line. Since the line is shared read-only, all copies in the shared cache 208 and shared memory 210 caches are the same. The shared memory 210 is therefore able to directly supply the data for this request. However, the shared caches 208 that have a copy of the cache line must lock that line to other requesters (e.g., requestors 204 ) and notify any requestor 204 to invalidate the line before the shared memory 210 sends the data to the original request.
In more concrete terms, assume that the first shared cache 208 a has made a request to make a currently shared read only cache line exclusive. As such, the first shared cache 208 may also be referred to herein as the requesting shared cache 208 a . Also assume that the second shared cache 208 b has a copy of the cache line as does requester 206 a . The shared memory 210 sends a request to the second shared cache 208 b information to invalidate the cache line. In turn, this causes the second shared cache 208 b to send a command (coherency check) to requester 206 a informing it to invalidate the line. However, this command must be executed without any delay because, as discussed above, the shared memory 210 is free to source date to the requesting shared cache. To ensure that the request is sent from the shared cache 208 b and received by the requester 206 before the shared memory begins sourcing data to the first requestor 208 a , the second shared cache 208 b may be configured to operate in a particular manner. For instance, the second shared cache 208 b may ensure that the coherency updates will be sent to the lower level caches (e.g., requesters 206 ) with a fixed delay from when they are received from shared memory 210 . It shall be assumed that once received by the requestors 206 , the command will be executed.
FIG. 3 shows an example of shared cache 302 coupled to a lower level cache 304 . In this example, the shared cache 302 may be coupled to several additional lower level caches (not shown). The shared cache 302 may receive off chip coherency requests from an external memory such as the L4 cache 110 . The shared cache 302 includes a cache controller 306 . In one embodiment, the shared cache 302 has a fixed limit to the number of off chip coherency requests from the L4 cache 110 it can process at any given time. This limit shall be referred to as a off chip coherency limit herein. In one embodiment, the shared cache 302 may be able to handle 12 off chip coherency checks from the L4 cache 110 . In such an embodiment, the off chip coherency limit would be 12. It shall be understood that the L4 cache 110 may be replaced with other types of requestors.
The cache controller 306 may include a request handler 306 . In normal operation, the request handler 308 receives many different types of requests. For example, the request handler 308 may receive off chip coherency requests, fetch requests and store requests, among others. The request handler 308 assigns the requests to state machines 310 based on the type of request it is. In one embodiment, all off chip coherency requests are assigned to a particular state machine or set of state machines. The size of the set of these dedicated state machines may be equal to the off chip coherency limit. For example, in FIG. 3 state machines 310 a - 310 l may be reserved for off chip coherency checks and the remainder for other operations. All of the state machines 310 may be coupled to and provide cache pipeline requests to an arbiter 312 . This arbiter 312 selects requests to provide to the shared cache pipeline 314 . In another embodiment, specific state machines may not be reserved. Rather, from the set of state machines 310 a number of them are reserved to ensure that all of the requests up to the off chip coherency limit may be immediately accepted.
In the event that an off chip coherency request from the L4 cache 110 is received by the request handler 308 , as discussed above, embodiments disclosed herein ensure that that coherency updates will be sent, and received, by the lower level cache 304 within a delay equal to or less than a fixed time delay limit. To this end, in the event that the request handler 308 receives an off chip coherency request from the L4 cache 110 , the request handler 308 assigns the request to one of the reserved or otherwise available state machines 310 . In addition, request handler 308 notifies the arbiter 312 that such a request has been received and where it has been assigned. In the case where the arbiter 312 is implemented in hardware, the notification may force the arbiter 312 to select the state machine 310 to which the request was assigned. The arbiter 312 then causes the off chip coherency request to be passed into the shared state machine 314 . The shared state machine 314 then sends, without delay, the coherency requests to the lower level cache 304 . In this manner, the shared cache 302 can ensure that coherency updates are sent within the fixed delay.
In addition, as described above, the shared cache 302 may also be required to ensure that the coherency request is received before the L4 cache 110 begins sourcing data. In one embodiment the lower level cache 304 may include a coherency queue 316 . The coherency queue 316 is a stack that stores coherency requests received from the shared cache 302 . The cache controller keeps track of the number of coherency requests it has sent to the lower level cache 306 in a counter 318 . The counter 318 incremented whenever a coherency request is sent and decremented when the request is removed from the coherency queue 316 (i.e., it is processed by a lower level cache state 320 ). As discussed above, the coherency queue 316 may include x slots. To ensure that the coherency queue 316 has room to accept all coherency requests that are the result of off chip coherency requests, the shared cache 302 reserves a number of slots, reserved slots 322 , in the coherency queue 316 . This may be accomplished by halting coherency requests from other than off chip coherency requests when the counter 318 is equal to the number of slots in the coherency queue 316 less the off chip coherency limit (e.g., x-off chip coherency limit).
In addition, upon receipt of the off chip coherency request, the shared cache 302 may invalidate the cache line of interest in its cache directory 322 to ensure that no other requestors may access the line. In one embodiment, any requests active in the shared cache 302 that involve the cache line at the time the coherency check is received from the L4 cache 110 are terminated.
As discussed above, in a multi level cache hierarchy, it may be advantageous for lower level caches to guarantee the availability of resources for processing coherency requests from a higher level cache in a timely manner in order to avoid coherency problems and optimize system performance. A simple way of doing this is to allocate a fixed number of resources to the processing of these coherency requests from the higher level cache. This ensures that resources are always available to process the coherency update. However, the resource being reserved may be a scarce resource and a large number of them need to be reserved to guarantee availability for off chip coherency updates. This lessens their availability for coherency requests originating from on chip requests. As the requests sourced from off chip (e.g., from L4 cache 110 ) are guaranteed to go, they are therefore higher priority than the on chip requests, which means that the on chip requests may be delayed more than necessary by the off chip requests. This negatively impacts the performance of the local on chip requests.
Accordingly, one embodiment of the present invention is directed to a method to dynamically balance the resource reservation in a manner that guarantees their availability for off chip coherency requests while not penalizing requests from local operations. In this embodiment, the resources being reserved are coherency queues 316 on each lower level cache 304 coupled to the shared cache 302 .
FIG. 4 is a flow chart showing a method of dynamically balancing resource reservations. At a block 402 off chip coherency request data is gathered. The data includes: the number of available resources on each lower level cache, the maximum number of remote coherency updates that may be simultaneously processed by the shared cache, the number of reserved resources currently in use on each lower level cache, and the number of state machines in the shared cache currently processing remote coherency updates.
At a block 404 , the number of reserved resources used and the number of shared cache state machines in use processing a request are combined to form an adjustment value. If the state machine to process an off chip coherency requests is busy, then there is no need to reserve resources for them any longer.
At a block 406 , the number of reserved slots in the coherency queue for each lower level cache is reduced by the adjustment value. In terms of FIG. 3 , the limit on counter 318 may be raised by the number of adjustment value. This frees up additional resources to be used by local (e.g., on the shared cache) requestors. As the state machines finish their operation, they first check to ensure that a sufficient number of resources are available for future off chip coherency updates at a block 408 before it responds, at a block 410 , that its request is complete. That may include determining that each coherency queue includes at least one open slot. If not, the state machine will delay its response until such a condition exists. After the response is made, the number of reserved resources is increased at a block 412 . This may be accomplished, for example, by decreasing the limit on counter 318 .
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.
As will be appreciated by one skilled in the art, aspects of the present invention may be embodied as a system, method or computer program product. Accordingly, aspects of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module” or “system.” Furthermore, aspects of the present invention may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon.
Any combination of one or more computer readable medium(s) may be utilized. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.
A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.
Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.
Computer program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).
Aspects of the present invention are described below with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function/act specified in the flowchart and/or block diagram block or blocks.
The computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.
The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
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A cache includes a cache pipeline, a request receiver configured to receive off chip coherency requests from an off chip cache and a plurality of state machines coupled to the request receiver. The cache also includes an arbiter coupled between the plurality of state machines and the cache pipe line and is configured to give priority to off chip coherency requests as well as a counter configured to count the number of coherency requests sent from the cache pipeline to a lower level cache. The cache pipeline is halted from sending coherency requests when the counter exceeds a predetermined limit.
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[0001] The invention is directed to a snow shovel having a blade with bottom ribs or vanes. These ribs or vanes both cut into the snow and allow the shovel to glide over uneven surfaces beneath the snow.
[0002] Although the invention is described and referred to specifically as it relates to a blade having associated rear vanes for snow removal, it will be understood that the principles of this invention are equally applicable to similar devices, structures and methods for snow removal and accordingly, it will be understood that the invention is not limited to such devices, structures, machines and methods for snow removal.
BACKGROUND
[0003] In general snow shovels and scoops are used to clear paths and drives and the like, which are usually asphalt, concrete or stone, in areas where the snow lies for some time. The earth freezes and thaws with temperature variation, especially at the start and end of winter. The resulting frost heaves the asphalt, concrete or stone of the path or drive, breaking the smooth surface. Snow shovels and scoops inevitably collide and jar with the heaved elements, to the annoyance of the user. The applicant has found that the modified shovel of the invention collides much less frequently, and glides much more smoothly over frost heaved surfaces.
PRIOR ART
[0004] U.S. Pat. No. 1,264,433, 30 Apr. 1918, Posten, teaches a shovel having angled runners to carry the blade above surface obstructions. U.S. Pat. No. 2,545,226, 13 Mar. 1951, Claude, teaches a leaf scoop with front guide bar having ridges and grooves for ground contact. U.S. Des. Pat. 411,420, 22 Jun. 1999, Rose, teaches a snow shovel with longitudinal grooved ridges curved at the front, which could be used to raise the blade edge over uneven surface. U.S. App. 2005/0184542, 25 Aug. 2005, Moreschini et al. teaches a shovel having a wedge protuberance extending two inches backward and extending across the entire front of the blade, on encountering uneven surface, the handle is tilted down raising the front of the wedge and allowing it to glide over uneven surface.
[0005] U.S. Des. Pat. 187,874, 10 May 1960, Cross, teaches a snow plough blade backed by curved strips which would allow the blade to be raised to glide over uneven surfaces. Canadian Pat. 687,138, 26 May 1964, teaches a snow scoop with skids either tangential to the blade or further back, both sets of skids are used to raise the blade over uneven surface. U.S. Pat. No. 3,218,738, 23 Nov. 1965, Bowerman, teaches a roof snow scoop with skids at the blade edge to space the blade edge from the roof. U.S. Des. Pat. 242,761, 21 Dec. 1976, DiCarlo, teaches a snow scoop with a circular disc side, which allows the blade edge to be raised over uneven, surface. U.S. Pat. No. 4,153,287, 8 May 1979, Towsend, teaches a shovel blade with semirigid bristles projecting from its bottom, letting the blade edge clear uneven surface. U.S. Pat. No. 4,386,474, 7 Jun. 1983, Mechavich et al., teaches a snow hoe shoe (roof rake) with hoop shoes at the blade edge to space the blade edge from the roof. U.S. Pat. No. 5,511,327, 30 Apr. 1996, Jurkowski et al., teaches a shovel blade with a squeegee projecting from its bottom, letting the blade edge clear uneven surface. U.S. Pat. No. 5,676,413, 14 Oct. 1997, Hauck, teaches a roof rake with paired rollers at the blade edge, to space the blade edge from the roof. U.S. Pat. No. 5,845,949, 8 Dec. 1998, to Vosbikian, teaches a snow shovel with a recessed scraping (blade) edge to avoid surface contact. U.S. Pat. No. 5,956,873, 28 Sep. 1999, Hess, teaches a roof rake with paired semicircular guides near the blade edge, to space the blade edge from the roof.
[0006] U.S. Pat. No. 4,193,626, 18 Mar. 1980, Vondracek, teaches a scoop with a front edge angled flange to aid in gliding over uneven surfaces.
[0007] U.S. Pat. No. 173,209, 8 Feb. 1876, Campbell, teaches a scoop with runners to prevent the blade edge touching the surface. U.S. Pat. No. 180,543, 1 Aug. 1876, Campbell, teaches a scoop with runners to prevent the blade edge touching the surface, with small wheels at the leading edge. U.S. Pat. No. 258,260, 23 May 1882, Staples, teaches a scoop with runners U.S. Pat. No. 289,131, 27 Nov. 1883, Patten, teaches a box scoop with runners, the blade edge is lowered in use. U.S. Pat. No. 787,921, 25 Apr. 1905, Hooper, teaches a scoop with runners. U.S. Pat. No. 1,445,952, 20 Feb. 1923, Hooper, teaches a scoop with runners. U.S. Pat. No. 1,678,135, 24 Jul. 1928, Crosman et al., teaches a scoop with runners. U.S. Pat. No. 1,766,691, 24 June 1930, Rugg, teaches a scoop with flat runners, the scoop is tilted down to collect snow. U.S. Pat. No. 2,933,836, 26 Apr. 1960, McKinley, teaches a scoop with a flush front edge and curved runners to ease tipping or dumping snow. U.S. Des. Pat. 271,369, 15 Nov. 1983, Gesner, teaches a scoop with runners. U.S. Pat. No. 5,271,169, 21 Dec 1993, Konsztowicz, teaches a snow pusher with runners, the blade may be raised to avoid snagging the ground.
[0008] U.S. App. 2005/0230985, 20 Oct. 2005, Thiele, Jr., teaches a shovel with a scalloped blade edge.
[0009] In general as is ascertained from the toboggan art, the function of runners, skids, ridges, or guides whether curved, bevelled, or flat is to reduce the frictional surface in contact with the snow, and thus the friction itself. In combination with a shovel or scoop blade, they would lift the blade edge above the snow surface, and not clear snow from the ground surface. Moreschini's flat wedge bottom pushes the blade upward toward the snow and away from the ground surface. None of the prior art teaches a snow shovel which both cuts down to the ground surface and glides smoothly over ground irregularities.
DESCRIPTION OF THE INVENTION
[0010] In one broad aspect the invention is directed to a snow removal device, most preferably a shovel, although some lighter forms of scoop may embody the invention, comprising a blade having a horizontal ground engaging leading edge extending across the front of the blade and an array of spaced apart vanes protruding from the rear of the blade, substantially perpendicular to the blade and the leading edge. The vanes have bottom surfaces lying in a plane aligned with the leading edge, which is use is normally substantially horizontal. Typically both blade and vanes are thin. Preferably the leading edge comprises a horizontal cutting edge extending across the front of the blade, and a wedge extending rearward from the cutting edge. The wedge has a top surface angled upward and rearward of the cutting edge, a planar bottom surface extending rearward from the cutting edge. The top surface of the wedge comprises the front surface of the blade, and the bottom surface of the wedge comprises the bottom surfaces of the vanes and the bottom surface of the blade. Usually the front surface of the blade curves upward and rearward. Usually the bottom surface of the blade is coplanar with the bottom surfaces of the vanes, unless the bottom surface of the blade is vanishingly thin. Preferably the rear ends of the bottom surfaces of the vanes are aligned substantially parallel to the leading edge and the rear ends form a trailing edge. The trailing edge can be used to pivot blade, wedge, leading edge and cutting edge upward by the user. More preferably the rear ends of the bottom surfaces are rounded. Typically the blade is a sheet having opposed front and rear surfaces. Preferably the blade is concave forward, curving upward from the leading edge. Conveniently the blade is part of the inner surface of a cylinder, although this is not essential, as those skilled in the art appreciate. Preferably the blade can pivot about the trailing edge.
[0011] In a second broad aspect the invention is directed to an improved snow removal device having blade and attached shaft with handle, the improvement comprises the blade having a horizontal ground engaging leading edge extending across the front of the blade and an array of spaced apart vanes protruding from the rear of the blade, substantially perpendicular to the blade and the leading edge. The vanes have bottom surfaces lying in a plane aligned with the leading edge, which is use is normally substantially horizontal. Typically both blade and vanes are thin. Preferably the leading edge comprises a horizontal cutting edge extending across the front of the blade, and a wedge extending rearward from the cutting edge. The wedge has a top surface angled upward and rearward of the cutting edge and a planar bottom surface extending rearward from the cutting edge. The top surface of the wedge is the front surface of the blade, and the bottom surface of the wedge comprises the bottom surfaces of the vanes and the bottom surface of blade. Usually the front surface of the blade curves upward and rearward. Usually the bottom surface of the blade is coplanar with the bottom surfaces of the vanes, unless the bottom surface of the blade is vanishingly thin. Preferably the rear ends of the bottom surfaces of the vanes are aligned substantially parallel to the leading edge and the rear ends form a trailing edge. The trailing edge can be used to pivot blade, wedge, leading edge and cutting edge upward by the user. Preferably the rear ends of the bottom surface are rounded. Typically the blade is a sheet having opposed front and rear surfaces. Typically the blade is concave forward, curving upward from the leading edge. Conveniently the blade is part of the inner surface of a cylinder, although this is not essential, as those skilled in the art appreciate. Preferably the blade can pivot about the trailing edge.
[0012] In a third broad aspect the invention is directed to a snow removal device comprising a blade, attached shaft with handle, and the blade has a horizontal ground engaging leading edge extending across the front of the blade and an array of spaced apart vanes protruding from the rear of the blade and substantially perpendicular to the blade and the leading edge, the vanes having bottom surfaces lying in a plane aligned with the leading edge, which is use is normally substantially horizontal. Typically both blade and vanes are thin. Preferably the leading edge comprises a horizontal cutting edge extending across the front of the blade, and a wedge extending rearward from the cutting edge. The wedge has a top surface angled upward and rearward of the cutting edge and a planar bottom surface extending rearward from the cutting edge. The top surface of the wedge is the front surface of the blade, and the bottom surface of the wedge comprises the bottom surfaces of the vanes and the bottom surface of the blade. The rear ends of the bottom surfaces of the vanes are aligned substantially parallel to the leading edge to form a trailing edge. The rear ends of the bottom surface are rounded. The blade is a sheet having opposed front and rear surfaces. The blade is concave forward, curving upward from the leading edge. Conveniently the blade is part of the inner surface of a cylinder, although this is not essential, as those skilled in the art appreciate. The blade can pivot about the trailing edge.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 shows a sectional side elevational view of an embodiment of the invention.
[0014] FIG. 2 shows a detail of the embodiment of FIG. 1 .
[0015] FIG. 3 shows a top plan view of the embodiment of FIG. 1 .
[0016] FIG. 4 shows a rear elevational view of the embodiment of FIG. 1 .
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0017] The invention is illustrated by reference to preferred embodiments thereof. Numeral 10 denotes the snow shovel of the invention. Snow shovel 10 has blade 12 having cylindrical sheet 14 which has an array of vanes 16 projecting radially from the rear surface. Cylindrical sheet 14 has leading ground engaging edge 18 from which the bottom edges 20 of vanes 16 extend rearward. Leading edge 18 has cutting edge 36 and base 38 substantially coplanar with bottom edges 20 , which are aligned in a plane. Bottom edges 20 extend rearward to trailing edge 32 . Leading edge 18 normally is a wedge with an angle of about 20° extending rearward from cutting edge 36 , which is not critical, from about 15° or less to about 25° or more work. Socket 22 is attached to the rear of blade 12 , both directly and by struts 34 , socket 22 and struts 34 are attached to cylindrical sheet 14 by conventional fasteners 40 , which may be screws, nuts and bolts, pop rivets and the like. Socket 22 receives shaft 24 , typically cylindrical and about 1 inch (2% cm) diameter. At the outer end of shaft 24 ′is handle socket 26 and conventional handle 28 . In use leading edge 18 and cutting edge 36 slide along ground surface 30 , shown in ghost, removing snow and ice, while surfaces 38 and 20 skim along ground surface 30 . Blade 12 as shown is a portion of reinforced plastic sewer pipe, typically from 12 to 18 inches (30 to 45 cm) diameter and ⅛ inch (3 mm) thick, measuring about 18 to 24 inches (about 45 to 60 cm) wide, with vanes 16 projecting about ½ to 1 inch (1 to 2½ cm) from sheet 14 , vanes 16 are about 1/16 to inch (1½ to 3 mm) thick and evenly spaced about 1 inch (2½ cm) apart. Surface 38 is typically ¼ inch (6 mm) from front to rear, while surface 20 is about 1½ inch (3¾ cm) from front to rear. Curved sheet 14 generally subtends an angle of a third circumference) (120°) but this is not critical. In use of shaft 24 should approximate 45° to the horizontal or vertical for convenience, at this angle cutting edge 36 slides along ground surface 30 , while surfaces 38 and 20 skim along either level or at a slight rearward upward angle. In the presence of bumps handle 26 is lowered, cutting edge 36 is raised pivoting upward about trailing edge 32 of surface 20 , which is preferably rounded. At this angle cutting edge 36 clears most bumps, while surface 20 of vanes 16 glide over them. The configuration of the leading ground engaging edge of the blade and the vanes immediately rearward thereof has been found very effective in gliding over snow covered ground, level and irregular, while removing the snow.
[0018] The above-described details, materials and components are meant as illustrative only and not in a limiting sense.
[0019] As those skilled in the art would realize these preferred described details and materials and components can be subjected to substantial variation, modification, change, alteration, and substitution without affecting or modifying the function of the described embodiments.
[0020] Although embodiments of the invention have been described above, it is not limited thereto, and it will be apparent to persons skilled in the art that numerous modifications and variations form part of the present invention insofar as they do not depart from the spirit, nature and scope of the claimed and described invention.
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A snow shovel has a blade ending in a front leading cutting edge of wedge cross section. Rear vanes having coplanar bottom surfaces aligned with the cutting edge, terminate in a rounded trailing edge parallel to the leading edge. The blade leading edge can pivot upward about the trailing edge allowing the leading edge to clear irregular ground. The rear vanes cut through the snow to the ground surface, allowing minimal clearance by the leading edge and close snow removal.
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CROSS REFERENCE TO RELATED APPLICATION
This application is based upon, claims the benefit of, priority of, and incorporates by reference, the contents of Brazilian Patent Application No. PI 0603210-9 filed Aug. 15, 2006.
FIELD OF THE INVENTION
The present invention relates to the field of ionic liquids, more in particular to a method of preparing halogen-free ionic liquids produced from the cation 1,3-dialkylimidazolium.
BACKGROUND OF THE INVENTION
Ionic liquids, also know as molten salts, are made up of salts derived from tetra alkyl ammonium or phosphonium or, more frequently, made up of heteroaromatic cations associated with anions, such as, for example, BF 4 , PF 6 , CF 3 SO 3 , (CF 3 SO 2 ) 2 N, CF 3 CO 2 (P. Wasserscheid, T, Welton; Ionic Liquids in Synthesis, VCH-Wiley, Weinheim, 2002; J. Dupont; R. F. de Souza, P. A. Z. Suarez; Chem. Rev.; 2002, 102, 3667; P. Wasserscheid, W. Keim; Angew. Chem. Int. Ed.; 2000, 39, 3773; T. Welton; Chem. Rev.; 1999, 99, 2071), and in a general way these ionic liquids are mainly used industrially as reagents or solvents.
The most researched and used ionic liquids are those based on the 1,3-dialkylimidazolium cation, and its physical and chemical properties qualify it as a “green” solvent in many processes, such as, for example, processes of extraction/separation, synthesis, catalysis, electrochemical.
The use of ionic liquids as a “green” reaction medium is primordially described as substituent for conventional mediums in chemical processes.
With growing concerns about the environment, the use of ionic liquids as a reaction medium can provide a way to minimize the production of wastes. In ionic liquids it is possible not only to efficiently promote reactions, but also to contribute significantly to minimize solvent loss.
There are applications in which the ionic liquids play the role of lubricating agent between metallic parts that undergo a high level of mechanical wear. Again, the absence of free halogens that may form cells in the presence of small amounts of water or polar compounds is very important. It is known today, that in industry, minimal amounts (mg/L) of halogens compounds in pyrolysis furnaces feedstocks, for example, can lead to planned maintenance down time due to corrosion in the pipes or even disintegration of refractories.
Therefore, the use of ionic liquids in addition to providing ecological benefits, also translates into economic advantages.
The Article by J. S. Wilkes et al (Inorg. Chem.; 1982, 21, 1263) presents a synthesis of 1,3-dialkylimidazolium chlorides that makes it possible to introduce similar or different alkyl groups. Mixtures of these chlorides with anhydrous aluminum chloride, in various proportions, provide ionic liquids.
Another Article by J. S. Wilkes et al (J. Chem. Soc., Chem. Commun.; 1992, 965), explains a method for exchanging a chloride salt of 1,3-dialkylimidazolium ion with various anions, such as BF 4 and CH 3 CO 2 , by reacting imidazolium chlorides with a silver salt containing the desirable anion.
The Article by J. Dupont et al (Polyhedron; 1996, 15, 1217) describes a new method for this reaction, with a sodium salt used as the desired counter ion and acetone as solvent.
The Article by J. Dupont et al (Org. Synth.; 2002, 79, 236) presents a detailed optimization of the experimental procedure of replacing a halogen anion of the 1,3-dialkylimidazolium salts with BF 4 , PF 6 or CF 3 SO 3 .
The patent belonging to P. Wasserscheid et al (EP 03/02127, dated Sep. 12, 2003) describes the synthesis, through metathesis reactions, of some ionic liquids with a general formula of [cation]+.[ROSO 3 ]—. Thus, for example, the heating under vacuum of a mixture of 1-butyl-3-methylimidazolium with pyridinium diethylene glycol-monomethyl-ether-sulfate provides, after removing the pyridinium chloride by sublimation, the ionic liquid, butylmethylimidazolium diethylene glycol-monomethyl-ether-sulfate. In another procedure, a 1-butyl-3-methylimidazolium chloride interacts with ammonium diethylene glycol-monomethyl-ether-sulfate in CH 2 Cl 2 , the ammonium chloride precipitate was filtered and the filtrate was concentrated, yielding the ionic liquid, 1-butyl-3-methylimidazolium diethylene glycol-monomethyl-ether-sulfate.
The halogen metathesis method is well established nowadays; it allows synthetized, in a convenient manner, a wide range of ionic liquids derived from the cation 1,3-dialkylimidazolium. The residual contaminant is usually chloride that may be detected by testing with AgNO 3 (1.4 mg/L limit), ionic chromatography (under 8 mg/L, in accordance with C. Villangran et al; Anal. Chem.; 2004, in press), or by cyclic voltammetry (ppb, according to B. K. Sweeny et al; Electrochem. Commun.; 2001, 3, 712). The water content may be determined by Karl-Fischer titration or by cyclic voltammetry (V. Gallo et al; J. Chem. Soc., Dalton Trans.; 2002, 4339). The determination of the presence and quantity of these impurities is essential in many applications, because the physico-chemical properties of the ionic liquids may vary significantly, depending on the water or halogen content (K. R. Seddon et al; Pure Appl. Chem.; 2000, 72, 2275).
Some processes for obtaining halogen free ionic liquids are described in the literature.
In K. R. Seddon et al's patent (WO 01/40146, dated Jul. 6, 2001) a process is described where the salts of 1,3-dialkylimidazoliums are prepared by alkylation of 1-alkylimidazolium with trifluoroethyl acetate or with butyl methanesulfonate, under reflux and purification by vacuum and heat, followed by a metathesis reaction of the anions with acids, such as, for example, HBF 4 or HPF 6 .
In the Article by J. D. Holbrey et al (Green Chem.; 2002, 4, 407), 1-alkylimidazoliums are alkylated with dimethyl sulfate or with diethyl sulfate and, consequently, the anion (CH 3 OSO 3 or CH 3 CH 2 OSO 3 ) is exchanged for BF 4 , PF 6 or CF 3 SO 3 .
The Article by K. Mikami et al (Tetrahedron Lett; 2004, 45, 4429) describes obtaining a salt of 1,3-dialkylimidazolium chiral through alkylation of 1-methylimidazolium with the triflic ester derived from (S)-ethyl-lactate (Diagram 1).
The salt shown above is a solid one, however, metathesis with PF 6 allows a derivative of an ionic liquid to be obtained.
The Article by J. Dupont et al (Adv. Synth. Catal.; 2002, 344, 153), proposes a reaction where five components (glyoxal, formaldehyde, two different amines and an acid) are condensed to 1,3-dialkylimidazolium salts.
Undoubtedly, the derivatives of the cation 1,3-dialkylimidazolium associated with several anions are among the most investigated types of ionic liquids.
Very probably this is due to their facility to be synthesized, they are stable, and their physico-chemical properties can be fine-tuned by simply selecting the N-alkyl substituents and/or anions.
The great majority of these ionic liquids are usually prepared through the simple N-alkylation of N-alkylimidazol, generally using alkyl halogens as alkylation agents, followed by the association of metal halides or anion metathesis.
The anion metathesis procedures generate a great variety of ionic liquids based on 1,3-dialkylimidazolium of good quality.
Determining the purity of these ionic liquids is not a simple task. The principal contaminant is usually a residual halogen from the alkylation of imidazolium that may be detected by testing with AgNO 3 (1.4 mg/L limit), ionic chromatography (under 8 mg/L), or by cyclic voltammetry (ppb). The water content may be determined by Karl-Fischer titration or by cyclic voltammetry. The determination of the presence and the quantity of these impurities is essential in many applications, such as in catalysis and spectroscopic investigation, once the physico-chemical properties of the ionic liquids may vary significantly, depending on the water and/or halogen content.
At all events, as mention before, according to J. Dupont, et al, ionic liquids 1,3-dialkylimidazolium halogen free may be prepared from the reaction of five components (glyoxal, formaldehyde, two different amines and acids) and those containing alkyl sulfate or trifluoromethane sulfonate anions by the simple alkylation of 1-alkylimidazolium with the corresponding dialkyl sulfate or an alkyl trifluoromethane sulfonate ester, respectively.
Among the advantages of ionic liquids based on 1,3-dialkylimidazolium cations we can point out the following:
They are non-volatile, with no measurable vapor pressure; They are usually liquids within a wide range of temperatures (close to room temperature) and their viscosity is sufficiently low (<800 cP to 20° C.); They have thermal and electrochemical stability more suitable than the usual solvents; They dissolve a wide range of organic and inorganic compounds, on which their solubility may be adjusted by the choice of alkyl groups linked to the imidazole ring or by the nature of the anion; They are typically non-coordinate solvents; They are easily prepared from commercial reagents and through classic synthetic procedures.
Similar procedures to obtain ionic liquids which use alkyl sulfonates and alkyl phosphate as alkylation agents have been patented. However, in almost all the work carried out in this area it has been observed that there is a strong participation of halogenated materials, and no matter what future application in industrial units industries might be for these ionic liquids, it will be very important to guarantee the stability of these materials and preferably the absence of these anions in their free form.
Currently, ionic liquids such as [butylmethylimidazolium] PF 6 , [butylmethylimidazolium] BF 4 e [butylmethylimidazolium] (CF 3 SO 2 ) 2 N are commercially available, but with relatively high levels of chloride contaminants.
However, it is surprising that up to now there is no quick method available to prepare and to determine the purity of 1,3-dialkylimidazolium cation halogen free associated with the most popular and the most used anions such as PF 6 , BF 4 and (CF 3 SO 2 ) 2 N.
It is clear that there is a need for simpler and more practical methods to prepare halogen free ionic liquids and also there is a need for a quicker and more direct methodology to determine their purities.
SUMMARY OF THE INVENTION
In the present invention a simple and quick method to prepare halogen free ionic liquids, derived from the 1-alkyl-(C 1 -C 18 ), 3-alkyl-(C 1 -C 18 )-imidazolium cation, associated with the anions PF 6 , BF 4 , (CF 2 CF 3 ) 3 PF 3 , CF 3 SO 3 and (CF 3 SO 2 ) 2 N is presented, using a process with only two stages that may be sequential or not, at temperature close to room temperature and whose purity (>99%) may be determined using the 13 C satellites of the hydrogen nuclear magnetic resonance spectrum of the N-alkyl group as an internal standard, particularly the N-methyl group.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows the hydrogen nuclear magnetic resonance spectrum (500 MHz, 25° C.) of 1-butyl-3-methylimidazolium tetrafluoroborate (BMI.BF 4 ) in CD 2 C 12 ; and
FIG. 2 shows the expansion between 2.50 and 4.50 mg/L, showing the signals relating to the 13 C satellites and the signals relating to water and to CH 3 SO 3 group in the start-up compound (1-butyl-3-methylimidazolium methanesulfonate). (Relative intensities: a 13 C satellite=9.25, of the methanesulfonate anion=23.44 and of water=1.528).
DETAILED DESCRIPTION OF THE INVENTION
The present invention refers to a method to prepare ionic liquids, derived from the 1-alkyl-(C 1 -C 18 ), 3-alkyl-(C 1 C 18 )-imidazolium cation free of halogen, using a two stage process that may be sequential, or not, and that includes:
i) Alkylation of 1-alkyl (C 1 -C 18 )-imidazoliums with alkyl (C 1 -C 18 ) alkane (C 1 -C 18 ) sulfonates or with alkyl (C 1 -C 18 ) trifluoromethanesulfonate. ii) Metathesis reaction, in a water solution, of the alkyl (C 1 -C 18 ) alkane (C 1 -C 18 ) sulfonates with alkaline metal salts containing the anions PF 6 , BF 4 , CF 3 SO 3 , CF 3 SO 2 ) 2 N, (CF 3 CF 2 ) 3 PF 3 , and similar.
The determination of the purity of the ionic liquids is performed using the intensity of 13 C satellite signals from the hydrogen nuclear magnetic resonance spectrums in the N-methyl group as an internal standard.
Preferred Methods of Implementation
Herein after, we presented the preferred forms of implementation of the present invention, through some 1-alkylimidazolium alkylation reactions:
I) 1-alkyl (C 1 -C 18 )-imidazoliums were alkylated with alkyl (C 1 -C 18 ) alkane (C 1 -C 18 ) sulfonates by mixing the reagents in acetonitrile, chloridated solvents, or preferably, in the absences of solvents. In this procedure, the temperature of reaction must be kept between 0 and 80° C., preferably between 15 and 30° C., keeping the reagents in contact in a period of 6 to 96 hours. The alkyl groups of sulfonic esters that are linked to the oxygen atom may be primary or secondary, while the alkyl groups linked to the sulfur atom may be primary, secondary, or tertiary. II) 1-alkyl (C 1 -C 18 )-imidazoliums were alkylated with alkyl (C 1 -C 18 ) trifluoromethane sulfonates by mixing the reagents in chlorates solvents, preferably, in dichloromethane. In this procedure, the temperature of reaction must be kept between −10 and 25° C., preferably between 0 and 5° C., keeping the reagents in contact in a period of 1 to 4 hours. The alkyl groups of the trifluoromethane sulfonate esters that are linked to the oxygen atom may also be primary or secondary. III) The alkylation of 1-alkyl (C 1 -C 18 )-imidazoliums was also performed with alkyl (C 1 -C 18 ) trifluoromethane sulfonates generated in situ, through primary or secondary reactions of alcoholysis (C 1 -C 18 ) with anhydrous sulfonic trifluoromethane, in the presence of 1-alkyl (C 1 -C 18 ) imidazoliums and subsequent treatment of the reaction mixture with sodium carbonate.
EXAMPLES
Example 1
1-butyl-3-methyl imidazolium methane-sulfonate (BMI.CH 3 SO 3 )
Butyl methanesulfonate (45.60 g; 300 mmol) was mixed with 1-methyl imidazolium (24.60 g; 300 mmol) and the reaction mixture was allowed to stand at room temperature (25° C.) for 48 hours. After this period of time, an identical volume of acetone and one 1-butyl-3-methylimidazolium methanesulfonate crystal were added, in order to induce the crystallization of the product. The mixture was kept in the refrigerator overnight. A yellow, supernatant solution was decanted from the almost colorless crystals and the crystallization process was again repeated. After drying under vacuum, colorless BMI.CH3SO3 crystals were obtained (59.70 g; 85% yield); the melting point was 77.2° C., RMN— 1 H (CDCl 3 ) δ:
9.67 ( 1 H, s, C—H imidazolium);
7.47 (1H, t, J=1.8 Hz, C—H imidazolium);
7.36 (1H, t, J=1.8 Hz, C—H imidazolium);
4.11 (2H, t, J=7.2 Hz, NCH 2 );
3.89 (3H, s, NCH 3 );
2.59 (3H, s, CH 3 SO 3 );
1.72 (2H, quintet, J=7.2 Hz, CH 2 );
1.20 (2H, sextet, J=7.2 Hz, CH 2 );
0.79 (3H, t, J=7.2 Hz, CH 3 );
RMN— 13 C (CDCl 3 ) δ:
137.4; 123.5 and 121.8 (C—H imidazolium);
49.2 (NCH 2 );
39.4 (CH 3 SO 3 );
35.9 (NCH 3 );
31.7 and 19.0 (CH 2 );
13.0 (CH 3 ).
Example 2
1-Butyl-3-methylimidazolium 2-butanesulfonate
Butyl 2-butanesulfonate (24.88 g; 154 mmol) was mixed with 1-methyl imidazolium (12.30 g; 150 mmol) and the reaction mixture was allowed to stand at room temperature (25° C.) for 60 hours. After this period of time, the yellow reaction mixture became solidified. The crystalline mass was crushed, washed two times with ethyl acetate and dried under vacuum, which produced colorless crystals of 1-butyl-3-methyl imidazolium 2-butanesulfonate (33.10 g, 80% yield), melting point 76.1° C. RMN—1H (CDCl 3 ) δ: 9.80 (1H, s, C—H imidazolium); 7.53 ( 1 H, t, J=1.5 Hz, C—H imidazolium); 7.39 (1H, t, J=1.5 Hz, C—H imidazolium); 4.15 (2H, t, J=7.5 Hz, NCH 2 ); 3.92 (3H, s, NCH 3 ); 2.72-2.60 (1H, m, CH 3 CH 2 CH(CH 3 )SO 3 ); 2.20 5-2.05 (1H, m, CH 3 CH 2 CH(CH 3 )SO 3 ); 1.87 (2H, quintet, J=7.5 Hz, CH 2 ); 1.54-1.30 (3H, m, CH 3 CH 2 CH(CH 3 )SO 3 and CH 2 ); 1.32 (3H, d, J=6.8 Hz, CH 3 CH 2 CH(CH 3 )SO 3 ); 0.99 (3H, t, J=7.5 Hz, CH 3 CH 2 CH(CH 3 )SO 3 ); 0.94 (3H, t, J−7.5 Hz, CH 3 ). RMN— 13 C (CDCl 3 ) δ: 137.6; 123.6 and 121.8 (C—H imidazolium); 56.7 (CH 3 CH 2 CH(CH 3 )SO 3 ); 49.2 (NCH 2 ); 36.0 (NCH 3 ); 31.8; 24.6 and 19.0 (CH 2 ); 14.5; 13.1 and 11.5 (CH 3 ).
Example 3
1,3-dimethyl imidazolium methanesulfonate
Methyl methanesulfonate (5.50 g; 50 mmol) was mixed with 1-methyl imidazolium (4.10 g; 50 mmol) and the reaction mixture was allowed to stand at room temperature (25° C.) for 60 hours. After this period of time, the yellow reaction mixture became solidified. The crystalline mass was crushed, washed two times with ethyl acetate and dried under vacuum, which produced colorless crystals of 1,3-dimethyl imidazolium methanesulfonate (8.16 g, 85% yield), melting point 93.1° C. RMN— 1 H (CDCl 3 ) δ: 9.81 (1H, s, C—H imidazolium); 7.43 (2H, s, C—H imidazolium); 4.02 (6H, s, NCH 3 ); 2.79 (3H, s, CH 3 SO 3 ). RMN— 13 C (CDCl 3 ) δ: 138.5 and 123.3 (C—H imidazolium); 39.4 (CH 3 SO 3 ); 36.3 (NCH 3 ).
Example 4
1-butyl-3-methyl imidazolium trifluoromethane-sulfonate (BMI.CF 3 SO 3 )
4.1—First Variant:
Methyl trifluoromethanesulfonate (C. D. Beard et al; J. Org. Chem; 1973, 38, 3673) (4.26 g; 26.0 mmol) was added drop by drop, under stirring, into a cold solution (0° C.) of 2-butyl-imidazolium (3.10 g; 25.0 mmol) in 20 mL of dichloromethane. The resulting mixture was stirred for 30 minutes. 1 drop of water was added and shaken for one more hour. The reaction mixture was treated with anhydrous sodium carbonate and the resulting suspension was shaken for 30 minutes. Filtering followed by evaporation of the solvent produced the desired BMI.CF 3 SO 3 , a light yellow liquid (6.84 g; 95% yield). RMN— 1 H (CDCl 3 ) δ: 9.03 (1H, s, C—H imidazolium); 7.48 (1H, s, C—H imidazolium); 7.47 (1H, s, C—H imidazolium); 5 4.21 (2H, t, J=7.3 Hz, NCH 2 ); 3.97 (3H, s, NCH 3 ); 1.87 (2H, quintet, J=7.3 Hz, CH 2 ); 1.36 (2H, sextet, J=7.3 Hz, CH 2 ); 0.91 (3H, t, J=7.3 Hz, CH 3 ).
4.2—Second Variant:
1-Methyl-imidazolium (2.74 g; 33.3 mmol) was mixed together with n-butanol (2.47 g; 33.3 mmol) in 40 mL of dichloromethane and, under stirring and cooling in an ice bath, anhydrous sulfonic trifluoromethane (9.40 g; 33.3 mmol) was added drop by drop. After finishing the addition to the mixture, it was stirred for 1 hour at room temperature, to which a saturated aqueous solution of sodium carbonate (3.54 g; 33.3 mmol) was added. The solution was stirred for 30 minutes at room temperature. The phases were separated, with an organic dry phase that uses anhydrous sodium carbonate. The solvent was evaporated under vacuum and gently heated (50° C.), producing the desired BMI.CF 3 SO 3 (7.19 g; 75% yield), identical to the material obtained in experiment 1.2.4.1.
Example 5
Anion Metathesis Reactions
5.1—1-butyl-3-methylimidazolium tetrafluoroborate (BMI.BF 4 ).
A mixture formed by 1,3-dimethyl imidazolium methanesulfonate (BMI.CH 3 SO 3 ) (10.6 g; 45.0 mmol), sodium tetrafluoroborate (6.00 g; 54.5 mmol) and water (5.4 mL) was stirred at room temperature for 30 minutes. The resulting mixture, made up of two phases, was extracted with dichloromethane (3×15 mL). The combined organic extract was dried with anhydrous sodium carbonate and the solvent was evaporated under vacuum and heated (80° C.), which produced the desired BMI.BF 4 ionic liquid. (9.35 g; 92% yield).
5.2—1-butyl-3-methylimidazolium hexafluorophosphate (BMI.BF 4 ).
A mixture formed by 1,3-dimethyl imidazolium methanesulfonate (BMI.CH 3 SO 3 ) (5.80 g; 24.6 mmol), sodium hexafluorophosphate (5.00 g; 29.8 mmol) and water (5.0 mL) was stirred at room temperature for 30 minutes. The resulting mixture, made up by two phases, was extracted with dichloromethane (3×10 mL). The combined organic extract was washed with water (2×20 mL) and dried with anhydrous sodium carbonate. The solvent was evaporated under vacuum and heated (80° C.), which produced the desired ionic liquid BMI.PF 6 (6.64 g; 95% yield).
5.3—1-Butyl-3-methylimidazolium N-trifluoro-sulfonamidate [BMI.(CF 3 SO 2 ) 2 N].
A mixture formed by 1,3-dimethyl imidazolium methanesulfonate (BMI.CH 3 SO 3 ) (4.26 g; 18.2 mmol), lithium N-trifluoro sulfonimidate (5.47 g; 19.1 mmol) and water (10.0 mL) was stirred at room temperature for 45 minutes. The resulting mixture, made up by two phases, was extracted with dichloromethane (3×15 mL). The combined organic extract was washed with water (1×20 mL) and dried with anhydrous sodium carbonate. The solvent was evaporated under vacuum and heated (80° C.), which produced the desired ionic liquid BMI.(CF 3 SO 2 ) 2 N (7.33 g. 96% yield).
Example 6
Determination of the Purity of Ionic Liquid
The purity of the ionic liquids may be conveniently determined by the hydrogen nuclear magnetic resonance using the signals from the 13 C satellites (1.11% natural abundance) where the intensity of each 13 C satellite represents 0.56%. For example, the ionic liquids derived from the 1-butyl-3-methylimidazolium cation obtained through the metathesis reaction of alkylsulfonates with the alkaline salts of tetrafluoroborate, hexafluorophosphate, N-trifluor-sulfonimidate, etc., the residual sulfonate alkanes are quantified using the intensity of the 13 C satellite signals from the N-methyl radical of the imidazolium nucleus of the product as a standard (the intensity of each 13 C represents 0.56%), in the hydrogen magnetic resonance spectrum ( FIG. 1 ). The residual amount of water may also be quantified in this manner.
Notwithstanding the fact that this invention has been presented in accordance with its preferred implementations, those well acquainted with the technology will be able to see that variations and modifications may be made to the present invention, without distracting from its spirit and scope, which are defined by the following claims.
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The reaction of N-alkylimidazol with alkyl sulfonates, at room temperature, favors the production of 1,3-dialkylimidazolium alkane-sulfonates as crystalline solids at high yields. The alkane-sulfonate anions may be easily substituted by a series of other anions [BF 4 , PF 6 , PF 3 (CF 2 CF 3 ) 3 , CF 3 SO 3 and (CF 3 SO 2 ) 2 N] through simple anion, salt, or acid reactions in water at room temperature. The extraction with dichloromethane, filtration, and evaporation of the solvent, allows the production of the desired ionic liquids at a yield of 80-95%. The purity of these ionic liquids (in some cases >99.4%) is performed using the intensity of 13 C satellite signals from the magnetic resonance spectrums of the N-methyl imidazolium group as an internal standard.
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TECHNICAL FIELD
[0001] The present invention relates generally to sensing and estimation systems and, more particularly, to a system and method for electrical parameter estimation.
BACKGROUND OF THE INVENTION
[0002] Sensing a parameter of interest is an important task in any automatic and/or monitoring system. Moreover, digital sensors have very convenient features that allow for very complex processing capabilities. However, the tradeoff for convenience and features is cost.
[0003] Sensing is typically made by some measurement that can be translated to a variable of interest. Often times there are off-the-shelf transducers (or chips) configured to provide a voltage as their output which can be provided to an analog-to-digital (A/D) converter for further processing and/or transmission. Some chips even provide a digital stream of bits with the variable of interest encoded therein. It is also conventional to use a processing unit (PU) or the like to either (1) perform the A/D conversion via a built-in A/D and converter and/or (2) to handle/process the incoming bit stream.
[0004] While it is known to use a processing unit (e.g., microcontroller) with an A/D converter function to measure some electrical parameter of interest (e.g., resistance, capacitance, inductance), there is often a tradeoff between cost and performance. In other words, while a conventionally configured, low-cost microcontroller may be adequate where sampling throughput requirements are not very high, for high sampling rate situations they are typically not viable options. It would thus be desirable to be able to utilize a low-cost microcontroller to achieve, in effect, high sampling rate performance.
[0005] There is therefore a need for a system and method that minimizes or eliminates one or more of the problems set forth above.
SUMMARY OF THE INVENTION
[0006] The invention provides a system and method to achieve a high effective sampling rate using a low-cost microcontroller or the like. Embodiments of the invention may be used, for example, for dynamic electrical parameter estimation (e.g., for estimation of resistance, capacitance and/or inductance of a circuit).
[0007] A method is provided for estimating an electrical parameter of a circuit-under-test. In concept, the invention calls for acquiring multiple samples from multiple charging cycles, rather than acquiring multiple samples from just one charging cycle as is conventional. The timing of the sampling within each charging cycle is adjusted and controlled so that representative samples are taken at various time constants, albeit occurring in different charging cycles. This approach allows for the use of a low-cost, low throughput microcontroller, since there is no need to have a high throughput device capable of taking all the samples during one charging cycle.
[0008] The method includes a number of steps. The first step involves defining a major sampling period having a plurality of minor sampling periods. The next step involves, for each minor sampling period: (i) resetting or otherwise assuring that the circuit-under test is in a known state (e.g., is discharged); (ii) applying an excitation signal to the circuit-under-test to thereby produce a respective induced, response signal; and (iii) acquiring a respective sample of the induced signal at a respective, predetermined deferral time. In an embodiment where the circuit-under-test includes an unknown capacitance to be estimated, the resetting step includes the sub-step of discharging the circuit-under-test or ensuring that it is discharged. In such an embodiment, the excitation signal may be a unit step while the induced signal increases in accordance with a charging time constant indicative of the unknown capacitive. The final step involves determining the electrical parameter (e.g., capacitance) based on the acquired samples.
[0009] In a preferred embodiment, the samples, in the collective, define a composite response. The composite response is processed, for example, by fitting it to a normalized capacitive charging curve, to ascertain an estimate of the capacitive (i.e., the electrical parameter).
[0010] A system is also presented.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The present invention will now be described by way of example, with reference to the accompanying drawings:
[0012] FIG. 1 is a schematic and block diagram showing an environment in which the invention may be practiced.
[0013] FIG. 2 is voltage versus time diagram showing, in normalized fashion, a capacitor charging characteristic.
[0014] FIG. 3 is a flowchart showing a method in accordance with the invention for estimating an electrical parameter of a circuit-under-test.
[0015] FIG. 4 is a voltage versus time diagram showing a major sampling period subdivided into a plurality of minor sampling periods.
[0016] FIG. 5 is a simplified schematic and block diagram showing a conventional input to an analog-to-digital (A/D) converter.
[0017] FIG. 6 is a voltage versus time diagram showing data obtained using an embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0018] Referring now to the drawings wherein like reference numerals are used to identify identical components in the various views, FIG. 1 is a simplified schematic and block diagram of a system 10 configured for dynamic electrical parameter estimation. The system 10 includes a processing unit (PU) 12 , an optional first interface 14 , a circuit-under-test 16 and an optional second interface 18 . The circuit-under-test 16 may be characterized by one or more electrical parameters which may be of interest and which may need to be estimated, such as resistance, capacitance and/or inductance. For purposes of description, the electrical parameter of interest for the circuit-under-test 16 is capacitance. This is represented as a capacitor 20 having an unknown capacitance value, herein designated Cx. A well known approach for determining the value of an unknown capacitance is to charge the capacitance through a known resistance, and to then measure the voltage levels throughout the single charging cycle at various points in time. From these voltage level samples, one can determine a charging time constant, and if the resistance is known, the capacitance value can be calculated.
[0019] In this regard, for purposes of charging the circuit-under-test 16 , the PU 12 is configured to produce an excitation signal 20 on an output terminal thereof. The excitation signal 20 may be a unit step function signal. Of course, other signals are possible depending on the nature of the circuit-under-test 16 . In addition, in the case where the electrical parameter of interest is capacitance, the first interface 14 includes a charging resistor, such as a resistor 24 , having known resistance R Ω. In general, when the excitation signal 22 is applied to the circuit-under-test 16 , an induced voltage signal 26 is produced on an electrical node 28 . The induced signal 26 may be sampled by an analog-to-digital (A/D) converter included in the PU 12 , as shown in FIG. 1 . This may be done directly. Alternatively, however, and as shown, the induced signal 26 may be applied through the optional second interface 18 to produce an induced signal 26 ′, which is then sampled by the A/D of the PU 12 . In one embodiment, the interface 18 includes an operational amplifier 30 configured to present a relatively low output impedance for improved performance, as described in greater detail below.
[0020] The PU 12 may be a conventional microcontroller, including at least one microprocessor or other processing unit, associated memory devices such as read only memory (ROM) and random access memory (RAM), a timing clock, one or more inputs for monitoring input from external analog and digital devices and one or more outputs for controlling output devices. As described above, in the illustrative embodiment, the PU 12 includes at least one output configured to generate the excitation signal 20 . The PU 12 also includes at least one input, such as an analog-to-digital (A/D) converter input, for acquiring samples of the induced signal 26 (or 26 ′) at predetermined times under the control of a control program or the like executing in the PU 12 . The sampled signal 26 (or 26 ′) converted by the A/D results in a digital word having a predetermined number of bits, as known. The digital words are stored for further processing, as described below. The PU 12 can be of the low-cost variety, having reduced throughputs (e.g., 30-70 k Samples Per Second (SPS)).
[0021] FIG. 2 is voltage versus time diagram showing, in normalized fashion, a capacitor charging curve 32 . When the excitation signal 22 , which may be a unit step, is applied to the circuit-under-test 16 through the charging resistor 24 , the induced response signal 26 will take the form of the curve 32 . The X-axis in FIG. 2 is normalized and denotes any combination of resistance values (R) and capacitance values (Cx) (i.e., the X-axis is expressed in units of time constants—t/RCx). One approach to determine the value of the unknown capacitance is to fit the acquired data (e.g., using a least squares fit) to the data expressed in graph form in FIG. 2 . For example, a plurality of points 34 1 , 34 2 , 34 3 , 34 4 and 34 5 taken from curve 32 correspond to samples for each integer increment of the RCx time-constant. This data may be stored in a chart or table for use during execution. For instance, if a 5V unit step is applied to the RCx network, the capacitor voltage at any given time ‘t’ would be Vo=5 (1−exp (−t/RCx)). From this equation, one can obtain Cx since R, t and Vo are known: Cx=−t/(R (In (1−(Vo/5)))). This equation can be used for any single sample obtained. For a more accurate measurement, a set of estimations given by the last equation can be averaged.
[0022] As described in the Background, one issue involves price/performance tradeoffs for the PU 12 . If, as a rule of thumb to accurately estimate capacitance, one wishes to take one sample at least every time constant, the sampling period (T) would be defined as the product of (R)(Cx). For example, for a resistance value of R=1 MΩ and a capacitance value of Cx=1 pF, the sampling period would be T=(1E6)(1E−12)=(1E−6)=1 μs, or in other words, a requirement of 1 million samples per second. Low-cost microcontrollers presently can only usually reach about 30-70 kSPS (thousands of Samples Per Second). Accordingly, achieving such sampling rates using conventional approaches would rule out the use of conventional low-cost microcontrollers, which would be throughput-limited using conventional sampling approaches. The invention, however, provides a solution enabling even such low-cost microcontrollers to effectively achieve elevated performance levels.
[0023] FIG. 3 is a flowchart diagram describing a method of the invention which solves these and other problems. Generally, the invention solves these problems by establishing a separate charging cycle for each sample that is to be acquired, rather than trying to acquire all the samples on a single charging cycle using a throughput-limited device. Low-cost microcontrollers are generally not fast enough to acquire all the samples needed for parameter estimation during a single charging cycle, particularly for very short time-constant circuits-under-test. For each charging cycle (also referred to as the “minor sampling period”), the excitation signal 22 is applied and the sample is acquired in such a way that it is acquired at the same point in its individual charging cycle as it would have been had all the samples been taken off the same charging cycle. The samples are then considered together to form a composite response to the excitation signal 22 . The method for implementing this approach begins in step 31 .
[0024] In step 31 , the method involves defining a major sampling period that is subdivided into a plurality of minor sampling periods. The major sampling period defines the overall period of time in which samples are being taken to form the composite response, which is in turn used to determine a value for an electrical parameter of interest. The minor sampling periods define independent charging cycles for which at least one sample of the induced signal can be acquired. The minor sampling periods may be selected to be long enough to acquire a sample over at least two time-constants. In the illustrated embodiment, the minor sampling periods are at least five time-constants long. The individual samples are then added to the set of samples that collectively define the composite response. The method proceeds to step 33 .
[0025] In step 33 , the method involves performing, for each minor sampling period: (i) resetting, discharging or otherwise ensuring that the circuit-under-test 16 is in a known state (e.g., discharged); (ii) applying the excitation signal 22 to the circuit-under-test 16 to thereby charge, in the case of a capacitor, the circuit-under-test 16 and thus produce a respective induced, response signal 26 ; and (iii) acquiring a respective sample of the induced signal 26 at a respective predetermined deferral time. Thus, each minor sampling period defines its own independent charging cycle for the purpose of acquiring a sample at the predetermined, deferral time. Also, as alluded to, the respective deferral times are each selected so that, in the aggregate, the set of acquired samples fairly characterizes the charging response, and meets predetermined sampling criteria as if all the samples had been taken from one charging cycle. In one embodiment, the deferral times are selected so that at least one sample is taken for each time constant. The method proceeds to step 35 .
[0026] In step 35 , the method involves determining the electrical parameter based on the plurality of acquired samples. In effect, the plurality of samples are taken together to define a composite response produced by the applied excitation signal 22 .
[0027] FIG. 4 is a voltage (charge) versus time diagram showing operation of the dynamic electrical parameter estimation to illustrate the invention. The entire time period during which samples are acquired by the PU 12 may be defined as the major sampling period 36 , which in turn is subdivided into a plurality of minor sampling periods (or charging cycles), such as minor sampling periods 38 1 , 38 2 , 38 3 , 38 4 and 38 5 . In the illustrative embodiment, the minor sampling periods are equal, although this is not per se required. At the beginning of each minor sampling period 38 i , the circuit-under-test 16 , specifically the capacitance thereof, is assumed to be discharged. This may be due to natural discharge to ground, or may be controlled directly by the PU 12 by, for example, bringing the terminal on which the excitation signal is generated directly to ground so as to provide a discharge path. Other approaches are possible and remain within the spirit and scope of the invention. The main point is that the circuit-under-test 16 is in a known, preferably discharged state. For each of the minor sampling periods 38 1 , 38 2 , 38 3 , 38 4 and 38 5 , the excitation signal 22 (e.g., unit step) is applied to commence the charging cycle of the combination of the resistor 24 (R) and the circuit-under-test 16 (Cx). The trajectory of the voltage due to the charge build-up on capacitor 20 is shown at 39 1 for the minor sampling period 38 1 , shown at 39 2 for the minor sampling period 38 2 , shown at 39 3 for the minor sampling period 38 3 , and so on.
[0028] Each minor sampling period 38 i has a respective predetermined deferral time associated therewith. For the exemplary five minor sampling periods 38 1 , 38 2 , 38 3 , 38 4 and 38 5 as shown, there are five corresponding predetermined deferral times designated 40 1 , 40 2 , 40 3 , 40 4 and 40 5 , respectively, each measured or taken with respect to the beginning of its minor sampling period. The processing unit 12 is configured to delay the start of the A/D converter in acquiring samples by these amounts of time. As shown in FIG. 4 , a plurality of samples 42 1 , 42 2 , 42 3 , 42 4 and 42 5 are acquired at respective deferral times of 0.5, 1.0, 1.5, 2.0 and 2.5 (i.e., each tick mark in FIG. 4 is equal to 0.5). For each sample, the capacitor 20 of the circuit-under-test 16 is first charged and once the sample is taken, the capacitor is discharged or allowed to discharge for the next-succeeding minor sampling period (charging cycle). A curve can be traced through the acquired samples 42 1 , 42 2 , 42 3 , 42 4 and 42 5 so that the samples define, collectively, a composite response to the excitation signal (unit step).
[0029] FIG. 5 is a simplified schematic and block diagram showing a typical input interface to an analog-to-digital (A/D) converter that would be internal to a conventional processing unit. On-chip A/D converters (i.e., internal to the microcontroller itself) are typically connected through an interface to an external pin or terminal for receiving the analog voltage to be converted. This interface may include a resistor 50 (having a resistance value Rswitch, typically 5-10 k Ω), a switch 52 (S 1 ) and a capacitor 54 (having a capacitance value Chold, typically 5-10 pF). The resistance and the capacitance components present a load, which has the effect of deforming the acquired data (e.g., as shown above, FIG. 2 ). In another aspect of the invention, however, the second interface 18 includes the operational amplifier 30 configured in a unity gain follower arrangement. The operational amplifier 30 exhibits a reduced output impedance, as compared to the resistor 24 (R) and capacitor 20 (Cx) network, thereby minimizing distortion when its output is sampled by the A/D.
[0030] FIG. 6 is a voltage versus time diagram showing data obtained through the use of an embodiment of the invention. In particular, FIG. 6 shows data obtained in an embodiment where R=121 kΩ and Cx=12 pF. In this embodiment, the maximum sampling period is calculated as follows: R*Cx=1.45 μs. It should be appreciated that in FIG. 6 , a 0.5 μs “sampling period”, in effect, was achieved. The sampling rate is only limited by the timing of a machine cycle of the PU 12 .
[0031] Many variations of embodiments of the invention are possible. For example, when estimating capacitance, the RC network under test can be fully charged to an initial value, and the above-described samples can be acquired while allowing the circuit-under-test to discharge. Also, for example, if highly accurate capacitance measurements (or a very stable sampling period) are required, a ceramic resonator can be added to the system 10 to enforce greater precision in the timing of the various minor sampling periods, the deferral times, and the like. It should be understood that variation in the timing of acquiring a sample can result in sampling a higher or lower voltage than intended, and result in variation in the calculation of Cx. Another source of accuracy is the relative precision of the value of resistor 24 (R) (i.e., variation in R would likewise affect the calculation of Cx). On the other hand, if only relative (rather than absolute) capacitance measurements are required, then a ceramic/crystal resonator might not be required. In addition, while five minor sampling periods are shown in an illustrative embodiment, the invention contemplates that greater or fewer than five minor sampling periods may be appropriate under various circumstances (e.g., 2, 3, 4 or 6, 7 or higher).
[0032] The invention provides an affordable configuration for dynamic estimation of an electrical parameter, so long as output refresh rates do not exceed the capability of the processing used in any constructed embodiment. While the illustrative embodiment involved estimation of a capacitance value, it should be understood that the invention is not so limited, and may be extended to and applied to any electrical network including, alone or in combination, a resistance, capacitance and/or an inductance.
[0033] It should be understood that the processing unit (PU) 12 as described above may include conventional processing apparatus known in the art, capable of executing pre-programmed instructions stored in an associated memory, all performing in accordance with the functionality described herein. That is, it is contemplated that the processes described herein will be programmed in a preferred embodiment, with the resulting software code being stored in the associated memory. Implementation of the invention, in software, in view of the foregoing enabling description, would require no more than routine application of programming skills by one of ordinary skill in the art. Such a processing unit may further be of the type having both ROM, RAM, a combination of non-volatile and volatile (modifiable) memory so that the software can be stored and yet allow storage and processing of dynamically produced data and/or signals.
[0034] While particular embodiments of the invention have been shown and described, numerous variations and alternate embodiments will occur to those skilled in the art. Accordingly, it is intended that the invention be limited only in terms of the appended claims.
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A method is provided for estimating an electrical parameter of a circuit-under-test (e.g., resistance, capacitance and/or inductance). The method acquires samples during a plurality of charging cycles rather than during just one, which allows an extended overall time period to acquire such samples. The first step involves defining a major sampling period having a plurality of minor sampling periods. A number of steps are performed for each minor sampling period: applying an excitation signal to the circuit-under-test to produce a respective induced, response signal and acquiring a respective sample of the induced signal at a respective predetermined deferral time. In an embodiment where the circuit-under-test includes an unknown capacitance, the excitation signal may be a unit step while an increase in the induced signal is governed by a charging time constant, which itself is indicative of the unknown capacitive. The electrical parameter may be determined based on the acquired samples, which collectively constitute a composite response. The composite response is processed, for example, by fitting it to a normalized capacitive charging curve, to ascertain an estimate of the unknown capacitive.
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CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims benefit of U.S. Provisional Patent Application Ser. No. 60/572,319 entitled “Optical Polishing Pitch Formulations”, filed May 19, 2004.
BACKGROUND OF THE INVENTION
In the fabrication of precision optical components (telescope mirrors, lenses for imaging systems, laser windows, etc.), achievement of surface form and finish is critical. To rough out the basic optical form, any number of processes may be employed including diamond machining, abrasive grinding, or even molding. Such processes, however, produce only imprecise surface form and leave a rough surface finish. Even extremely fine grinding, using grit sizes in the few micron range, yields a microscopically pitted and frosty surface. Precision optical fabrication, therefore, requires a finishing step to achieve near molecular level smoothness and extreme accuracy in final surface figure. This final operation, commonly referred to as polishing, is generally critical within the field of precision optical fabrication.
Within the last few decades, tremendous advances have been made in the general art of surface polishing. Techniques such as chemical mechanical planarization (CMP) are now available for economical achievement of nanometer scale smoothness in semiconductor manufacturing. For optical polishing, magnetorheological finishing has proven value in specific precision finishing applications. For the manufacture of most precision optical components, however, traditional lap polishing remains the most economical and viable approach.
Remarkably, Sir Isaac Newton is credited with inventing the lap polishing method, which in essential respects is the basis for most modern precision optical finishing. Newton found that although fine grinding leaves optical surfaces microscopically pitted, an incredibly smooth finish might be obtained on glass (and like surfaces) if worked against a pitch material in the presence of a slurry containing soft abrasive particles. In the roughly 300 years since Newton originally published this technique, the basic methodology has become a staple optical finishing technique.
In pitch lapping, a hard support is typically coated with a layer of natural pitch, comprised of pine rosin or petroleum based resin, to form a lap of cut or molded pitch facets. Often, the pitch is melted, cast directly onto the support, cut into facets or, in some other fashion, molded into facets attached to the rigid support. Pitch, formulated for this application, displays slow creep or flow under the action of stress (although it outwardly appears as a hard resinous solid much like amber or hard sugar candy). Pressed against an optical workpiece, pitch facets slowly conform to provide an intimate mate with the surface. Subsequent working against the lap, in the presence of a particle slurry leads to charging of the lap surface with embedded particles. As a result, particles entrapped at the pitch surface are delicately dragged over the work and, through complex mechanisms, smooth the surface to produce an extremely high polish. Beyond polishing, lapping also delicately removes material from the optical surface and, thus, enables extremely fine adjustment of surface figure at the final stages of finishing.
Although the underlying mechanisms of pitch polishing remain a subject for investigation, pitch flow or creep is accepted as an important enabling phenomenon. Apparently, flow of the lap to mate with the optical surface is needed for the achievement of both uniform polish, and control of surface figure. Certainly, it is widely accepted that materials, which do not flow and conform to the optical work must either be preconditioned to provide conformance, or produce poor polishing results. Waxes, for example, produce a polishing effect but often with characteristic non-uniform lemon peel texture. Materials such as TEFLON fluorocarbon polymers may also be used for lapping but only following exhaustive diamond conditioning to provide close mating. Flow in pitch, thus, offers a practical means to achieve intimate microscopic lap mating and consequent polishing uniformity/control.
Due to the importance of flow in lap performance, optical polishing pitches are commonly formulated to possess levels of flow appropriate for a given application. The so called hardness of a pitch, or its resistance to flow in response to stress, is determined by mixing resins with different characteristics or plasticizing a given material with additives. Generally, pine rosin, plasticized with turpentine or other similar materials, has long been used as a polishing pitch. For example, one published account of a pitch formulation containing pine rosin dates back to the 1940s.
Currently, several brands of optical polishing pitch, blended to achieve different levels of hardness, are available commercially. Swiss manufactured GUGOLZ pitches, based on proprietary pine derivatives, are used extensively within the field of precision optics. Universal Photonics, Inc. of Hicksville, N.Y., also offers similar polishing pitches formulated across a very broad range of hardness. Beyond pine derivatives, Cycad Products, of Las Vegas, N. Mex., offers a range of pitches based on proprietary petroleum refining residuals and these pitches also find specific applications in optical finishing.
While the use of pine and petroleum resins as a base for optical polishing pitches has a long history, associated technology has specific limitations, which are addressed by the current invention.
Pine based pitches are typically derived from gum pine rosin, or similar related materials which, chemically, are largely comprised of materials refined from the sap of pine trees. While these materials are dominantly comprised of resin acids (such as abietic acid), exact weight distribution among these acids vary and many residual compounds are present depending on pine species, harvest location, and growing conditions. Consequently, the exact chemical makeup of pitches thus derived is difficult to control and, inherently, comprises an extremely complex blend of compounds, which are difficult to reproduce consistently over time. Similarly, petroleum based pitches, derived from refining residuals, contain a complex blend of isomers, oligimers, cyclic anthracitic compounds, and the like, depending on exact crude source.
While in principle it is possible to manufacture consistent optical pitches derived from either pine resin or petroleum pitch, chemical complexity and inconsistency in raw natural constituents present significant practical barriers the achievement of precise physical properties. Pine derivatives from a given source, such as Hercules, Inc. in Brunswick, Ga., for example, contain variable fractions of low molecular weight compounds, which, like turpentine added to deliberately induce creep characteristics, induce varying levels of hardness. Since even a fraction of one percent (by weight) of low molecular weight constituents changes flow characteristics dramatically, precise blending with additives to achieve precise pitch hardness is hampered by associated variability. Similarly, pitches derived from petroleum residuals contain small fractions of low molecular weight compounds, which vary in concentration and composition, leading to analogous difficulty in precision control of hardness.
Variability in the physical properties of natural pitches, particularly hardness, is a serious issue in the manufacture of precision optics. Since reproducibility in polishing operations depends upon the properties of the pitch employed, lot-to-lot variability in pitch characteristics translates into costly and unwanted process troubleshooting.
Notwithstanding ongoing efforts to characterize and track the lot-to-lot properties of existing natural pitches, variability is a major current issue for most manufacturers of precision optics. While quality control measurements of natural pitch characteristics may be employed to select and screen lots of material for a given finishing operation, such screening is time consuming and generally costly. Consequently, lower variability alternatives would represent a fundamental advancement in the art of optical polishing.
Beyond the issue of chemical purity and consistency in manufacture, existing pine and petroleum pitches are relatively unstable both during melt molding to produce laps and in use. Since the base resins typically comprise low molecular weight components, melting or long-term exposure to air can lead to significant changes in hardness due to loss of low boiling volatiles. For this reason, opticians must take great care in the melting of pitch (to fabricate laps) such that exposure to high temperature and drying/hardening of the material is limited. In addition, laps constructed of such pitches have a limited life in part due to drying of volatiles from the material and consequent hardening.
It is also important to recognize that many existing natural pitch formulations, particularly those comprising pine derivatives, are subject to reactions with oxygen over time. Most pine derivatives, for example, become rancid much like unsaturated fats or cooking oils, within a few weeks on exposure to air due to oxidative reactions. Although formulation with additives may inhibit such reactions to some extent, oxidation is another inherent instability associated with natural resins.
In large part due to the above issues, current practitioners in the art of pitch polishing face many practical complexities and must, in general, develop considerable formulation and processing expertise to achieve success. Blending of different commercial pitches is often required to overcome variability in hardness and or polishing performance. All too often, trial and error blending to modify hardness, enhance surface wetting, or insure proper charging with polishing agents, is necessary. In addition, extreme care is required in molding of natural pitches to prevent, degradation or drying of the material during melt processing, requires considerable care and experience. While many opticians have developed remarkable skill and intuition in the general art of pitch manipulation, more stable and pure materials, having precise and controlled properties, would enable more systematic, and less costly, optical process engineering. In general, the ability to scientifically formulate exact hardness targets, utilizing materials having known chemistry in combination with additives yielding well-characterized effects, would be of great value in many optical polishing applications.
What is needed, therefore, are pitch materials comprising chemically pure substances, which may be precisely formulated to yield precision control of physical properties including pitch hardness. In addition, such materials are needed which do not contain significant volatile content and, thus, are not susceptible to drying over time or during melt processing. Finally, optical polishing pitches, which are impervious to oxidation on exposure to air, are generally needed in the art.
BRIEF SUMMARY OF THE INVENTION
The present application is generally directed to specific synthetic polymers and resins, which when blended with plasticizing additives exhibit creep or flow characteristics analogous to those of existing optical polishing pitches. Given the synthetic and highly processed nature of these polymers and resins, associated chemical composition is relatively pure. Thus, with appropriate choice of pure additives to induce creep, these materials enable precise formulation to achieve exact composition targets and precision control of material properties. These materials enable lap polishing much like existing natural pitch counterparts.
Beyond the ability to formulate polymeric or synthetic resin materials having appropriate flow characteristics for use as pitches in optical polishing, we further find that specific embodiments of these materials are highly stable both with respect to loss of volatiles and oxidation. With appropriate choice of resin and additives, formulations are disclosed which do not display significant changes in physical properties as a consequence of melt processing and/or long-term exposure to air during use or storage.
In an embodiment of the present invention, a synthetic optical polishing pitch is formulated for polishing an optical surface. The synthetic optical polishing pitch can include a synthetic polymeric substance such as a poly(alpha-methyl)styrene polymer. More particularly, the polymeric substance can be the poly(alpha-methyl)styrene, a vinyl, a polystyrene, a polymer resin, or any combination of these materials.
In this aspect of the invention, the optical polishing pitch can further include a plasticizer mixed with the synthetic polymeric substance. The plasticizer can be an oil such as a mineral oil, which induces creep into the polymeric substance. In other words, the oil affects viscosity and malleability of the polymeric substance. By way of example, Duoprime® 200 mineral oil can be utilized as the plasticizer. A ratio of the plasticizer to poly(alpha-methyl)styrene polymer is about 50-50 to about 11-89 by weight. Alternatively, the ratio can be about 11-89 to about 8-92 by weight, or about 8-92 to about 1-99 by weight.
Also in this aspect of the invention, the optical polishing pitch can include a colorant mixed with the synthetic polymeric substance to affect opacity of the mixture and thus opacity of the optical surface. A wax such as beeswax can also be mixed with the synthetic polymeric substance to affect a surface characteristic of the optical pitch.
In another embodiment of the present invention, an optical polishing pitch for polishing an optical surface can be an artificial resin such as Regalrez® resin, Kristalex® resin, Kristalex® 3085 resin Piccotex® resin, a hydrogenated pine resin derivative or any man-made resin similar to these exemplary resins, including any combination of these artificial resins.
As in the foregoing embodiment, the artificial resin can be mixed with a plasticizer, such as a mineral oil, in various ratios to affect of viscosity and malleability of the resin. For example, the resin and the plasticizer can mixed in a range of 50/50 to 11/89 by weight. More particularly, the ratio can be within the range of 11/89 to 8/92 by weight, or within the range of 8/92 to 1/99 by weight. As noted above, Duoprime® 200 mineral oil, or equivalent oil, can be used as the plasticizer.
In another embodiment of the invention, a method of preparing an optical polishing pitch includes the steps of heating a synthetic pitch material until molten; mixing a plasticizing agent with the synthetic pitch material to form a pitch mixture; solidifying the pitch mixture; bonding the pitch mixture to an optical surface such as by heating the pitch mixture, the optical surface or both; and working the pitch mixture on the optical surface to attain a polished optical surface.
In the exemplary method, the synthetic pitch material can be a polymeric material, an artificial resin, a hydrogenated pine resin derivative and combinations of these materials. As in the previous aspects of the invention, the plasticizing agent can be an oil such Duoprime® 200 mineral oil. Also similar to the foregoing aspects of the invention, the plasticizing agent and the synthetic pitch material can be mixed in various ratios to affect creep, such as about 50-50 to about 1-99 by weight.
Further, according to the method, the synthetic pitch material is heated in an oven at a temperature greater than 135 degrees Celsius for about 1 hour to about 4 hours. Once the synthetic pitch material nears liquification, the plasticizing agent and the synthetic pitch material are mixed by stirring until a homogeneous liquor is obtained, which may exhibit a clear, yellowish appearance.
The method can include the additional step of adding a porous particulate such as alumina to the plasticizing agent and the synthetic pitch material to enhance surface charging for working the pitch mixture.
The method can also include the steps of adding a wax such as beeswax to the plasticizing agent and the synthetic pitch material to affect a surface characteristic such as to enhance surface charging for working the pitch mixture.
In yet other steps, the method can include adding a colorant such as carbon black to the plasticizing agent and the synthetic pitch material to affect opacity and pigmentation of the pitch mixture and thus, opacity of the optical surface after polishing.
The method can also include the steps of adding shellac or a similar material to the plasticizing agent and the synthetic pitch material to enhance toughness of the polished optical surface.
Still further, the pitch mixture, when disposed on the optical surface, can be wetted such as with a soap and water solution and pressed on the optical surface for a period of about 30 minutes to about 8 hours to conform the pitch mixture to the optical surface before polishing.
To polish the optical surface, the method can include the additional step of coating the pitch mixture on the optical surface with cerium oxide powder and water slurry to work the pitch mixture.
DETAILED DESCRIPTION OF THE INVENTION
It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only and is not intended as limiting the broader aspects of the present invention.
In embodiments of the invention, thermoplastic polymers or resins are mixed, via melt processing or other means, with appropriate plasticizing agents (fluids or lower molecular weight polymers), to form a homogeneous mixture. Constituents are chosen to insure that the resultant mixture, owing to interaction between components, displays rheological characteristics enabling application as an optical polishing pitch. Preferably, constituents are further chosen to possess low volatile content, and stability against oxidation, to yield stable pitches, which can be precision, formulated and manufactured.
Although the rheology of natural polishing pitches is complex, and the molecular mechanisms which drive related characteristics in embodiments of the present invention are not completely understood, it is clear that many polymers and resins, when mixed with plasticizing fluids, display characteristics enabling use in polishing. Whatever the mechanisms, it is the creep phenomenon itself, initiated by the interaction of a plasticizing agent dissolved within a polymer or resin system, which is most relevant to the present invention. Ultimately, in fact, it is the ability to utilize embodiments of the invention in optical lapping which is crucial, notwithstanding overall rheological properties.
Because the mechanisms of plasticizer-induced creep are partially understood, polymer chemistries and characteristics appropriate for use in the invention are found empirically. Within a given polymer or resin chemistry, trials are carried out with suitable plasticizing agent candidates to determine whether homogeneous mixtures can be produced, and, most importantly, whether resultant blends exhibit appropriate creep. Typically, a small quantity of a particular polymer or resin is melted, or heated to high temperature, in the presence of the candidate plasticizer, and mechanically blended to achieve a homogenous mixture. If the blend remains homogenous upon cooling, the resultant material is tested to determine creep characteristics. Provided the material displays continuous flow when exposed to stress, relative concentrations of the constituents may be varied to determine formulation parameters sufficient to yield creep appropriate for optical polishing. Polishing trials, within a given application, may then be used, just as with natural pitch, to optimize the formulation.
Through the use of this methodology, a wide range of polymers and resins have been found which may be plasticized with specific fluids to yield materials suitable for use as optical polishing pitches. In addition, various materials have been found which, generally, do not yield suitable results. Although these results seem to indicate that certain classes of polymers are generally more suited for use in the present invention, observations of suitability are provided herein solely for the purpose of outlining preferred embodiments, but, in no way, are intended to limit the scope of the invention. Notwithstanding the finding of unsuitable specific polymers within a given polymer family, for example, subsequent application of the novel methods and concepts disclosed may lead to development of viable pitches using other fluids or polymers within the same category.
In general, we have found that many polymers, which tend to display less crystalline order, are good candidates for screening and trial for use in embodiments of the invention. We speculate that polymer molecules, which pack poorly and fail to crystallize, especially when intimately mixed with compatible lower molecular weight molecules, are sufficiently mobile within the disordered structure to enable slow flow in response to stress. Provided this is true, more crystalline polymers would tend to be more stable, even when heavily plasticized, due to tight packing, lower mobility, and a tendency towards crystallite separation from plasticizer rich domains. Notwithstanding this speculation, it is likely that both highly crystalline and more amorphous polymers may be utilized in specific embodiments of the present invention, although more crystalline choices may be more restrictive with respect to applicable plasticizers, and breadth of formulation parameters.
Among the vast number of polymers appropriate for use in the invention, those that are highly amorphous, commercially available in a wide range of molecular weights, cost effective, and highly chemically stable, are among the preferable choices. Such polymers include, but are not limited to, vinyls, polystyrenes, poly(alpha-methyl)styrenes, and cuomorone-indene resins. The most preferable polymers are brittle, highly amorphous materials which dissolve easily in solvents, such as acetone, commonly used for cleanup in optical shops. Specific grades of the Piccotex®, Kristalex®, and Regalrez® poly(alpha-methyl)styrene resins, for example, manufactured by the Eastman Chemical Company of Bristol, Tenn., are particularly well suited for application in embodiments of the present invention.
Any number of relatively pure, non-polymeric synthetic resins may also be employed in embodiments of the present invention. Synthetically hydrogenated abietic acid, synthesized from highly processed pine derivatives, for example, may be plasticized with various non-volatile oils and low molecular weight polymers to yield materials which exhibit continuous creep and which are appropriate for use as optical polishing pitches. Such materials are highly differentiated from existing natural polishing pitches in that the base resin is man synthesized from relatively pure, and highly processed, chemical species. In addition, these base resins are far more chemically stable, with respect to oxidation even at high temperatures, than unmodified natural pine resin counterparts. Generally, therefore, a wide class of other synthetically manufactured materials, which are not rigorously polymers, but which possess the desirable attributes of man made pure and stable chemistries, are useful in embodiments of the present invention. Such materials include, but are not limited to synthetic esters and like resins.
Plasticizer agents appropriate for use in the invention include substantially non-volatile fluids and resinous liquids. Plasticizers are used as softening agents and provide low temperature flexibility and weldability. Most preferably, such materials do not display significant evaporation at room temperature, such that resultant blends will not dry and change properties during manufacture, melt processing, use, or storage. Also, substantially hydrogenated or other chemistries are preferred which generally resist oxidation, or other chemical instability, at temperatures likely encountered in melt molding by opticians (up to temperatures of approximately 150° C.). In addition, plasticizing agents should be available in forms that, although not necessarily of exact chemical purity or single species, may be obtained over long periods of time having highly reproducible chemical composition.
Beyond these general characteristics, plasticizing agents must be compatible within the base polymer or resin selected for use in a given embodiment. Accordingly, the plasticizer should form a homogeneous and substantially stable composition when intimately mixed and blended into the base polymer or resin. In addition, it is imperative that the chosen plasticizer interact within the polymer matrix to enhance the tendency of the resultant composition towards continuous creep, enabling application in optical lapping.
Generally, the range of plasticizing agents which may be employed in the present invention is extremely broad and many commercial oils, plasticizers, tackifying agents, low molecular weight polymers, and the like, are appropriate for use in specific embodiments. Many base polymers and resins, including but not limited to, poly(alpha-methyl)stryrenes, may be plasticized with any number of mineral oils, including, but not limited to, various grades of the Citgo Duoprime® oils. Many other chemically compatible plasticizers are also commonly available including technical grades of mineral oil, glyceride oils, silicone oils, and many others. Low molecular weight polymers are also highly suitable for use including very low molecular weight species of polymers useful as base resins (low molecular weight fluidic Kristalex® resins, for example, are highly useful as plasticizers for Kristalex® and other specific polymers).
In the most basic embodiment of the invention, wherein an appropriate polymer or resin is blended with a suitable plasticizer, the compositional fraction of plasticizer may vary according to specific desired creep characteristics. Since the plasticizer serves to induce or enhance continuous creep, a higher fraction of this component is employed in situations requiring compliance on a short time-scale, and lower fractions are employed in situations requiring slower creep response.
In some embodiments of the present invention, wherein the base resin is a poly(alpha-methyl)styrene, polymer molecular weight is chosen to enable plasticization with non volatile and relatively stable oils having intermediate molecular weight. For example, various oils may be chosen that have a viscosity of from about 15 to about 70 cSt at 40° C. according to test ASTM D 445, such as from about 20 to about 60 cSt or from about 28 to about 50 cSt. When the viscosity is measured according to test no. ASTM D 2161, on the other hand, the oil may have a viscosity of from about 80 SUS to about 400 SUS at 100° F., such as from about 100 SUS to about 350 SUS, and more particularly from about 180 SUS to about 240 SUS.
Kristalex® 3085, for example, is found to yield a preferred range of compositions when blended with intermediate molecular weight mineral oils, such as Citgo Duoprime® 200, in the range of 1 to 25 percent by weight, and most preferably, when blended in the range of 2 to 11 percent by weight. When other polymers are employed, however, the useful range of plasticizer will depend on the exact makeup of the constituents, and associated interactions, to result in creep. Compositions in such embodiments, therefore, vary over a range that must be determined empirically.
As one of ordinary skill in the art will recognize, the base polymer or resin component utilized in embodiments of the present invention may itself, comprise a blend of polymers, synthetic resins, or polymers and synthetic resins, suitable for appropriate plasticization. Blends of different Regalrez® resins, for example, having different average molecular weight, would be entirely appropriate for use in specific embodiments. Similarly, the plasticizer agent may comprise a blend of one or more individual components, having different chemical composition (a blend of different Duoprime® oils for example).
One of ordinary skill in the art will further recognize that modifying additives may be incorporated within the basic synthetic compositions described herein, to optimize and enhance specific properties which impact lapping performance. In common natural optical pitch formulations, walnut shell flour, and various other porous wettable particulates are often incorporated, beyond the basic resin composition, to enhance surface charging with polishing agents and water wettability during lap polishing. Waxes, including beeswax, may also be incorporated to enhance charging and or manipulate surface characteristics. Colorants, such as carbon blacks, are often incorporated to manipulate opacity and pigmentation. Even materials such as shellac are commonly incorporated to enhance toughness and modify texture. In an exactly analogous fashion, these same modifiers, or similar materials, may be incorporated into the synthetic compositions described herein, to effect similar modification. Synthetic pitches, modified in this fashion are thus, also embodiments of the present invention.
EXAMPLE 1
A 10 percent blend, by weight, of Duoprime® 200 oil in Kristalex® 3085 resin was produced via melt blending. In a stainless steel pot, 17.10 pounds of Kristalex® 3085 resin, lot number JP1L1291, was mixed with 1.90 pounds of Citgo Duoprime® 200 oil, lot number 4144S0223, and heated in an oven at a temperature of 135° C. for a period of 4 hours. The molten material was manually stirred, using a paddle, until a homogeneous, clear yellowish, liquor was obtained.
The molten material was ladled into a series of containers and allowed to cool in ⅓ Kg blocks. One of these blocks was fractured to produce small pieces, several of which were welded together using a heat gun to produce a solid chunk which, following heating in hot water, was precisely rolled into a cylinder 0.74 inches in diameter. This cylinder was fractured to approximate length, roughly shaved using a razor blade, and sanded on its ends, to produce a precise cylinder 1.5 inches in length.
The ends of this cylinder were lubricated using silicone oil (Dow SF96-1000) and it was placed between two polished stainless steel platens, with the cylinder ends bearing flat on each platen. The sample was precisely equilibrated at a temperature of 22.5° C. A compressive force was then applied between the platens placing the sample under a compressive longitudinal stress of 8.2×10 4 Pascals. The sample was observed to exhibit continuous creep, decreasing in length at a strain rate of 2.7×10 −4 /s. A measure of sample compliance and creep, given by the stress divided by the strain rate, was calculated as 0.30 GPa-s. We note that under specific assumptions, including perfect slip boundary conditions at the platen interfaces and exact cylindrical symmetry in sample flow, this compliance value reduces to the Trouton viscosity of the material at this strain rate.
For reference only, a similar measurement was carried out on a sample of GUGOLZ 55 polishing pitch (lot number 208009) prepared in the same fashion and tested under similar conditions. The resultant sample compliance was calculated (as above) to be 0.36 Gpa-s, comparable to that of the 10 percent formulation above. We noted, therefore, a reasonable equivalence in creep characteristics between the 10 percent composition, and this particular lot of commonly used natural polishing pitch. We further note, however, that given the variability common in GUGOLZ pitch, and aging effects during storage in GUGOLZ pitch, this measurement is in no way intended to be reproducible in the future. Rather, it provided a comparison indicating a very general equivalency with a particular GUGOLZ 55 lot sold by Universal Photonics Inc. of Hicksville, N.Y.
Subsequently, another ⅓ Kg block of the 10 percent blend was cut into tiles, measuring approximately ¾ inch on a side and ¼ inch in thickness, and used to tile the surface of a 6 inch diameter glass blank 0.75 inches in thickness. Tiles were arranged, and bonded to the glass surface using a heat gun, in a square pattern leaving ⅛ inch gaps between tiles.
The resultant lap was wetted with soapy water and pressed with an optical flat for a period of 30 minutes. The tiles conformed to mate with the flat and conform across the entire lap surface, forming a well-conditioned flat surface for trial in polishing. A 3 inch diameter trial blank of Pyrex® glass was precision flat ground using a final alumina particle size of 9 microns. Cerium oxide powder, wetted with water on the finger, was coated on the surface of this trial blank and worked over the lap. As with normal pitch, a few minutes of working brightened the fine ground surface from having a frosty finish to show significantly polished appearance. Subsequent working, with cerium oxide slurry, produced a finished, highly polished, flat optical surface.
EXAMPLE 2
A 4 percent blend, by weight, of Duoprime® 200 oil in Kristalex® 3085 resin was produced via melt blending. In a stainless steel cup, 240 g of Kristalex® 3085 resin, lot number JP1L1291, was mixed with 10 g of Citgo Duoprime® 200 oil, lot number 414450223, and heated in an oven at a temperature of 135° C. for a period of 1¾ A hours. The molten material was manually stirred, using a spoon, until a homogeneous, clear yellowish liquor was obtained.
The molten material was ladled into a series of containers and allowed to cool in ⅓ Kg blocks. One of these blocks was fractured to produce small pieces, several of which were welded together using a heat gun to produce a solid chunk which, following heating in hot water, was precisely rolled into a cylinder 0.73 inches in diameter. This cylinder was fractured to approximate length, roughly shaved using a razor blade, and sanded on its ends, to produce a precise cylinder 1.64 inches in length.
The ends of this cylinder were lubricated using silicone oil (SF96-1000) and it was placed between two polished stainless steel platens, with the cylinder ends bearing flat on each platen. The sample was precisely equilibrated at a temperature of 22.5° C. A compressive was then applied between the platens placing the sample under a compressive longitudinal stress of 9.0×10 4 Pascals. The sample was observed to exhibit continuous creep, decreasing in length at a strain rate of 1.6×10 −6 /s. A measure of sample compliance and creep, given by the stress divided by the strain rate, was calculated as 55 GPa-s. We note that under specific assumptions, including perfect slip boundary conditions at the platen interfaces and exact cylindrical symmetry in sample flow, this compliance value reduces to the Trouton viscosity of the material at this strain rate.
Subsequently, pieces of this material were cut into tiles, measuring approximately ¾ inch on a side and ¼ inch in thickness, and used to tile the surface of a 6 inch diameter glass blank 0.75 inches in thickness. Tiles were arranged, and bonded to the glass surface using a heat gun, in a square pattern leaving ⅛ inch gaps between tiles.
The resultant lap was wetted with soapy water and pressed with an optical flat for a period of 8 hours. The tiles conformed to mate with the flat across the entire lap surface, forming a well-conditioned flat surface for trial in polishing. A 3-inch diameter trial blank of Pyrex® glass was precision flat ground using a final alumina particle size of 9 microns. Cerium oxide powder, wetted with water on the finger, was coated on the surface of this trial blank and worked over the lap. As with normal pitch, a few minutes of working brightened the fine ground surface from having a frosty finish to show significantly polished appearance. Subsequent working, with cerium oxide slurry, produced a finished, highly polished, flat optical surface.
These and other modifications and variations to the present invention may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention, which is more particularly set forth in the appended claims. In addition, it should be understood that aspects of the various embodiments may be interchanged either in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention so further described in such appended claims.
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Optical polishing pitch formulations include synthetic polymers or other synthetic resins. As alternatives to traditional optical pitches, these materials offer improved stability in use, storage, and processing. In addition, these pitch compositions may be masterbatched and manufactured with precision to ensure superior reproducibility and quality control in polishing performance.
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BACKGROUND OF THE INVENTION
This application relates to a refrigerant system utilizing tandem compressors sharing a common condenser, but having separate evaporators, and wherein an economizer circuit and a reheat coil are incorporated.
Refrigerant systems are utilized in applications to change the temperature and humidity or otherwise condition the environment. In a standard refrigerant system, a compressor delivers a compressed refrigerant to an outdoor heat exchanger, known as a condenser. From the condenser, the refrigerant passes through an expansion device, and then to an indoor heat exchanger, known as an evaporator. In the evaporator, moisture may be removed from the air, and the temperature of air blown over the evaporator coil is lowered. From the evaporator, the refrigerant returns to the compressor. Of course, basic refrigerant systems are utilized in combination with many configuration variations and optional features. However, the above provides a brief understanding of the fundamental concept.
In more advanced refrigerant systems, a capacity of the air conditioning system can be controlled by the employment of so-called tandem compressors. The tandem compressors are normally connected together via common suction and common discharge manifolds. From a single common evaporator, the refrigerant returns through the common suction manifold to each of the tandem compressors. From the individual compressors the refrigerant is delivered into the common discharge manifold and then into a single common condenser. The tandem compressors are also separately controlled and can be started and shut off independently of each other such that one or both compressors may be running at a time. By controlling which compressors are operating, control over the capacity of the entire system is achieved. Often, the two compressors are selected to have different capacities, such that even greater flexibility in capacity control is provided. Also, tandem compressors may have shutoff valves to isolate some of the compressors from the active refrigerant circuit, when they are shutdown. Moreover, if these compressors operate at different suction pressures, then pressure equalization and oil equalization lines are frequently employed.
One advantage of the tandem compressor is that more capacity control is provided, without the requirement of having each of the compressors operating on a dedicated circuit. This reduces the system cost.
However, certain applications require cooling at various temperature levels. For example, in supermarkets, low temperature (refrigeration) cooling can be provided to a refrigeration case by one of the evaporators connected to one compressor and intermediate temperature (perishable) cooling can be supplied by another evaporator connected to another compressor. In another example, a computer room and a conventional room would also require cooling loads provided at different temperature levels, which can be achieved by the proposed multi-temp system as desired. However the cooling at different levels will not work with an application of a standard tandem compressor configuration, as it would require the application of a dedicated circuit for each cooling level. Each circuit in turn must be equipped with a dedicated compressor, dedicated evaporator, dedicated condenser, dedicated expansion device and dedicated evaporator and condenser fans. This arrangement having a dedicated circuitry for each temperature level would be extremely expensive.
In addition, a technique known as an economizer circuit has been utilized in refrigerant systems. The economizer circuit increases the capacity and efficiency of a refrigerant system. To this point, a system having a common condenser communicating with several evaporators has not been utilized in combination with any economizer circuit. Notably, applicants have a co-pending application, filed on even date herewith, entitled “Refrigerant Cycle With Tandem Compressors for Multi-Level Cooling, and assigned Ser. No. 10/975,887.
In some cases, while the system is operating in a cooling mode, the temperature level at which the air is delivered to provide comfort environment in a conditioned space may need to be higher than the temperature that would provide the ideal humidity level. Generally, the lower the temperature of the evaporator coil is the more moisture can be removed from the air stream. These opposite trends have presented challenges to refrigerant system designers. One way to address such challenges is to utilize various schematics incorporating reheat coils. In many cases, a reheat coil placed in the way of an indoor air stream behind the evaporator is employed for the purposes of reheating the air supplied to the conditioned space after it has been cooled in the evaporator, where the moisture has been removed as well.
While reheat coils have been incorporated into air conditioning systems, they have not been utilized in an air conditioning system having an ability to operate at multiple temperature levels by employing tandem compressors, with at least one of the tandem compressors operating in conjunction with the economizer circuit.
SUMMARY OF THE INVENTION
For the simplest system that has only two compressors, in this invention, as opposed to the conventional tandem compressor system, there is no common suction manifold connecting the tandem compressors together. Each of the tandem compressors is connected to its own evaporator; while, both compressors are still connected to a common discharge manifold and a single common condenser. Consequently, for such tandem compressor system configurations, additional temperature levels of cooling, associated with each evaporator, become available. An amount of refrigerant flowing through each evaporator can be regulated by flow control devices placed at the compressor suction ports, as well as by controlling related expansion devices or utilizing other control means, such as evaporator airflow. In addition, in this application, an economizer circuit is incorporated into the refrigerant system. The economizer circuit maybe utilized with one or several of the evaporators. In particular, the economizer circuit may increase the capacity of each evaporator, and thus it would preferably be utilized (to obtain the most benefits) with the evaporator associated with the environment that must be controlled at the lowest temperature.
In addition, a single or multiple reheat coils are associated with one or several evaporators. The reheat coils may be positioned in a parallel or serial flow relationship with an economizer heat exchanger and condenser and can be located either upstream or downstream of each heat exchanger.
In embodiments, only one or several of the evaporators may be associated with the economizer circuit. In the economizer circuit, a portion of the refrigerant is then returned to an intermediate compression position in at least one of the compressors and can be tapped from the main circuit either upstream or downstream of the economizer heat exchanger, as known. Also, the teachings of this invention can be equally applied to compressors connected in series or economized compressors having multiple injection ports.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows an earlier system.
FIG. 2 is a first schematic.
FIG. 3A is a second schematic.
FIG. 3B shows another option.
FIG. 4 is a third schematic.
FIG. 5 is a fourth schematic.
FIG. 6 illustrates another option.
FIG. 7 illustrates yet another option.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1 , earlier tandem compressor system 10 is shown to include two separate compressors 11 , a common evaporator 17 , condenser 15 , expansion device 14 , condenser air-moving device 16 , evaporator air-moving device 18 and associated piping. An economizer circuit has an economizer heat exchanger 15 receiving a main refrigerant flow and a tapped refrigerant flow in line 7 . As known, the tapped refrigerant flow passes through an expansion device 9 to be expanded to lower pressure and temperature. Downstream of the economizer heat exchanger 15 , the tapped flow is returned through a line 8 to an intermediate point in at least one of the compressors 11 . Such a system was disclosed in a prior U.S. patent application Ser. No. 10/769,161, filed 30 Jan. 2004, entitled “Refrigerant Cycle With Tandem Economized and Conventional Compressors” and assigned to the assignee of the present invention. As known, the tap line 7 may also be located downstream of the economizer heat exchanger 15 .
A refrigerant system 20 is illustrated in FIG. 2 having a pair of compressors 22 and 23 that are operating generally as tandem compressors. Optional discharge valves 26 are positioned downstream of these compressors on discharge lines associated with each of the compressors 22 and 23 . These valves can be controlled to prevent backflow of refrigerant to either of the compressors 22 or 23 should only one of the compressors be operational. That is, if for instance the compressor 22 is operational with the compressor 23 stopped, then the discharge valve 26 associated with compressor 23 will be closed to prevent flow of refrigerant from the compressor 22 back to the compressor 23 . The two compressors communicate with a discharge manifold 29 leading to a common condenser 28 . From the condenser 28 , the refrigerant continues downstream and is split into two flows, each heading through an expansion device 30 . From the expansion device 30 , one of the flows passes through a first evaporator 32 for conditioning a sub-environment B. The refrigerant passing through the evaporator 32 passes then through a suction modulation valve 34 , and is returned to the compressor 22 . The second refrigerant flow passes through an evaporator 36 that is conditioning a sub-environment A. The refrigerant also passes through an optional suction modulation valve 34 downstream of the evaporator 36 and is returned to the compressor 23 . An air-moving device F drives air over the evaporator 32 and another air-moving device F drives air over the evaporator 36 and into their respective sub-environments. Usually, sub-environments A and B are preferably maintained at different temperature levels.
A control 40 for the refrigerant system 20 is operably connected to control the compressors 22 and 23 , the expansion devices 30 , the discharge valves 26 , and suction modulation valves 34 . By properly controlling each of these components in combination, the conditions at each evaporator 32 and 36 can be controlled as necessary for the sub-environments A and B. The exact controls necessary are as known in the art, and will not be explained here. However, the use of the tandem compressors 22 and 23 utilizing the common condenser 28 and separate evaporators 32 and 36 , preferably operating at different temperature levels, reduces the number of components necessary for providing the independent control for the sub-environments A and B, and thus is an improvement over the prior art.
As shown in FIG. 2 , an economizer circuit 100 is incorporated into the refrigerant system 20 . An economizer heat exchanger 102 receives a refrigerant from an economizer tap 104 and a main refrigerant flow line 106 . Notably, the refrigerant heading to the evaporator 32 does not pass through the economizer heat exchanger 102 , while the refrigerant heading to the evaporator 36 does. In this embodiment, the evaporator 36 and its sub-environment A is preferably the environment that must be maintained at a lower temperature. The use of the economizer circuit will provide additional cooling capacity for the evaporator 36 , as known. The refrigerant passing through the tap 104 passes through an expansion device 108 to be expanded to lower pressure and temperature. This refrigerant thus subcools the refrigerant in the main flow line 106 in the economizer heat exchanger 102 . The tapped refrigerant, having been expanded and passed through the economizer heat exchanger 102 , returns through a return line 110 to an intermediate compression point in at least one of the compressors, shown here as compressor 23 . Notably, while the flow in the lines 104 and 106 are shown in the same direction through the economizer heat exchanger 102 , for all of the embodiments in this invention, it is preferred that these two flows are arranged in a counter-flow relationship, however, they are shown in the same direction for illustration simplicity.
The use of the economizer circuit 100 provides additional cooling capacity to the refrigerant system 20 .
For this embodiment, and for all other disclosed embodiments, there is an option where the control can also selectively open the economizer expansion device to either allow flow through the economizer heat exchanger, or to block flow through the economizer heat exchanger. When the economizer expansion device is shut off, refrigerant would still pass through the economizer heat exchanger through the main flow line, however, the economizer function would not be operational. Rather than having a single economizer expansion device that also operates as a shut-off valve, two distinct flow control devices could be utilized. Also, as mentioned above, the tap refrigerant line 104 may be located downstream of the economizer heat exchanger 102 , providing similar benefits.
In addition, a reheat circuit is incorporated into the system 20 . In particular, the reheat circuit includes a flow control device 116 for selectively tapping a refrigerant through a reheat coil 118 associated with the sub-environment A. When the control 40 determines that a reheat function is desired, the valve 116 will be opened and refrigerant will pass through the reheat coil 118 , through a check valve 120 , and be returned at point 122 to the main refrigerant circuit, upstream of one of the expansion devices 30 . At least a portion of air driven by the air-moving device F over the evaporator 36 will also now pass over the reheat coil 118 . As is known, this air can be cooled in the evaporator 36 , and in particular cooled to a lower temperature by employment of the economizer circuit 100 , such that greater dehumidification can be achieved. If the temperature of the air having passed over the evaporator 36 is lower than would be desired in the sub-environment A, then the reheat coil 118 is utilized to heat the air to a desired temperature level after the moisture has been removed in the evaporator 36 .
Obviously, the economizer heat exchanger 102 and reheat coil 118 can be associated with different evaporators 32 and 36 if desired. Furthermore, although a warm liquid approach (with the reheat coil 118 located downstream of the condenser 28 and arranged in a parallel relationship with the economizer heat exchanger 102 ) is shown in FIG. 1 , any reheat concept (e.g. hot gas, warm liquid, two-phase mixture) as well as reheat circuit configuration and relative position can be employed, providing similar system advantages in flexibility and control of satisfying a wide spectrum of potential applications and various external sensible and latent load demands. Thus, in systems employing such reheat concepts, the position of the reheat coil in the refrigerant circuit in relation to the condenser 28 and economizer heat exchanger 102 may be sequential or parallel as well as upstream or downstream.
As shown in FIG. 2 , a bypass line 315 may bypass refrigerant around the condenser 28 when a flow control device such as valve 316 is opened. This bypass may be selectively utilized by the control 40 when dehumidification is desired with a lower sensible cooling load. Such bypasses are known in the art, and a worker of ordinary skill in this art would recognize how to incorporate this feature into the schematic 20 , and when to utilize the feature.
FIG. 3A shows another embodiment 50 that is quite similar to the embodiment 20 of FIG. 2 . However, the refrigerant flowing to both of the evaporators 32 and 36 passes through the economizer heat exchanger 102 . As shown, the main flow of refrigerant 106 leads to a downstream manifold 116 , which then breaks into branches leading to both evaporators 32 and 36 . The benefits of additional capacity are thus provided to both of the evaporators. As shown, the refrigerant being returned to the compressor 22 would still return through the line 110 . An optional line 114 may also return refrigerant to the other compressor 23 , if this compressor is equipped with intermediate injection port as well.
Reheat coils are also incorporated into the refrigerant cycle 50 . Here, a first three-way valve 52 is positioned downstream of the economizer heat exchanger 102 , and directs refrigerant through a first reheat coil 54 associated with the evaporator 36 and sub-environment A when a reheat function desired. Refrigerant flowing through the reheat coil 54 then passes through a check valve 56 , and is returned at point 58 to the main circuit refrigerant line, upstream of the expansion device 30 . In this case, a warm liquid approach is utilized once again, but now with the reheat coil 54 located downstream of both condenser 28 and economizer heat exchanger 102 . A second three-way valve 60 selectively taps refrigerant off of a main refrigerant line, and passes it through a second reheat coil 62 associated with the sub-environment B. Refrigerant flowing through the reheat coil 62 then passes through a check valve 64 and is reconnected at point 66 to the main refrigerant line. Here, a hot gas design is employed with the reheat coil 62 positioned upstream of the condenser 28 . The control 40 will selectively operate each of the reheat coils dependent on the desired humidification and temperature needs of the sub-environments A and B. As shown in FIG. 3B , both reheat coils 54 and 62 can be associated with a single evaporator ( 32 or 36 ) and consequently with a respective sub-environment (B or A), providing multiple reheat stages for this sub-environment. Although the reheat coils 54 and 62 are shown in series (one behind the other) relative to the air path, a parallel configuration is also feasible.
FIG. 4 shows a refrigerant cycle 80 , wherein, once again, there are reheat coils associated with each of the two sub-environments A and B. However, in this embodiment, a single three-way valve 82 is positioned downstream of the main flow line passing through the economizer heat exchanger 102 . Refrigerant having been tapped from the three-way valve 82 passes to a connection 94 , through two lines 86 , and selectively operable flow control devices 84 , can pass to the two reheat coils 88 and 90 . These two refrigerant flows recombine at a point 89 , pass through a check valve 92 , and are reconnected at the point 94 upstream of the expansion device 30 . Thus, in this relationship, the two reheat coils 88 and 90 are in generally parallel configuration such that the refrigerant conditions at the entrance to the reheat coils is generally the same. The control 40 will selectively operate both flow control devices 84 associated with the reheat coils 88 and 90 to be either open or closed to provide refrigerant flow to each of reheat coils associated with sub-environment B and A respectively when the reheat function is desired in each sub-environment. Obviously, the flow control devices can be of an adjustable type to control amount of refrigerant to each reheat coil through modulation or pulsation. As it would be recognized by a worker ordinarily skilled in the art, other parallel configurations of the reheat coils are also feasible.
FIG. 5 shows an embodiment 190 where the two reheat coils are in a serial flow relationship. A three-way valve 192 taps refrigerant through a first reheat coil 194 associated with the sub-environment B, and the refrigerant then passes downstream serially to a reheat coil 196 associated with the sub-environment A. The refrigerant then passes through a check valve 198 , and is reconnected at a point 200 to the main refrigerant flow. As can be appreciated, the refrigerant will have a higher temperature at the reheat coil 196 than it would at the reheat coil 194 , and thus the selection of which sub-environment A and B should first receive the refrigerant flow should be made based upon which sub-environment requires a higher amount of reheat. As it would be recognized by a worker ordinarily skilled in the art, other serial arrangements of the reheat coils are also feasible.
FIG. 6 shows yet another schematic 200 , wherein there are serially connected compressors 202 and 204 (instead of a single economized compressor). A discharge line 206 downstream of the second stage compressor 204 delivers refrigerant to a condenser 208 . A refrigerant line 210 downstream of the first stage compressor 202 accepts refrigerant from the economizer heat exchanger at an intermediate pressure level. Obviously, any economized compressor can be substituted by a serially connected compressor stages and more than two sequential compressor stages can be employed as well if desired.
FIG. 7 shows an embodiment 250 , having an economized compressor 252 , such as mentioned above, wherein there are plural intermediate taps 254 and 256 , each connected to a respective economizer heat exchanger operating at a different pressure and temperature level and thus providing different amount of subcooling. Such economizer heat exchangers can be arranged in a sequential or parallel configuration to each other. Of course, more than two taps are feasible.
In all of the disclosed embodiments, the economizer circuit and reheat coils assist in providing the distinct temperatures and humidity levels that are to be achieved by one or several of the evaporators. That is, by providing the economizer circuit and reheat coil, the present invention is better able to meet the temperature and dehumidification goals for a wide spectrum of potential applications as well as sensible and latent load demands.
Other multiples of compressors and compressor banks can be utilized.
Although preferred embodiments of this invention have been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
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A tandem compressor refrigerant system where an economizer circuit and reheat coil are incorporated to provide additional flexibility and control over overall system capacity and sensible heat ratio as well as to increase system efficiency. In this system, tandem compressors deliver compressed refrigerant to a common discharge manifold, and then to a common condenser. From the common condenser, the refrigerant passes to a plurality of evaporators, with each of the evaporators being associated with a separate environment to be conditioned. Each of the evaporators is associated with one or several of the plurality of compressors. By utilizing the common condenser, yet a plurality of evaporators, the ability to independently condition a number of sub-environments is achieved without the requirement of the same plurality of complete separate refrigerant circuits for each compressor. In particular, the economizer circuit provides additional capacity to any of the evaporators that have a relatively high load while the reheat coil provides improved dehumidification. Various design schematics and system configurations are disclosed.
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CROSS REFERENCE TO RELATED APPLICATIONS
The present application claims priority to European Patent Application No. 13161368.9 filed Mar. 27, 2013.
STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT
Not Applicable.
BACKGROUND OF THE INVENTION
The present invention relates to an edge profile for bordering the superstructure rescue vehicle, in particular a fire fighting vehicle.
Many aerial vehicles, especially fire fighting vehicles that are equipped with a turnable and extractable ladder, comprise a walking deck that can be entered by an operator to access the main operator seat at the turret of the ladder. In a very common construction the deck area is formed by an aluminum metal sheet with an anti-slip surface, which is bended and welded to the top of the vehicle body at its edges.
It has been envisaged to form the superstructure of such a vehicle as a modular system of extruded aluminum profiles. Such a system provides many benefits under the aspects of cost reduction and flexibility. However, until now there is no way how to combine the advantages of such a modular superstructure with a deck area formed by bended and welded metal sheets, as explained above. Moreover, it is desired to provide the superstructure of the vehicle with additional security features, especially related to an illumination of the deck, its borders and its environment so that the deck can be entered securely even in situations with poor visibility. Generally there is the desire for a bordering construction of the superstructure, especially for the deck of a rescue vehicle that fulfills all these requirements.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an edge profile for bordering a superstructure of a rescue vehicle, in particular a fire fighting vehicle, that fulfills all requirements of providing a simple and secure connection, especially within a modular construction system, for bordering of the top deck portion of the vehicle and the lateral side wall portion. It is another object to incorporate security features into this profile for visualizing the borders of the deck portion and illuminating the environment of the vehicle.
These objects are achieved by an edge profile comprising the features of claim 1 .
The edge profile according to the present invention comprises an extruded profile body with a cross section that comprises a central hollow portion and a first groove opening towards the upper side of the profile body in which a first band-shaped lighting device is arranged, a second groove opening laterally towards the bottom side of the profile body in which a second band-shaped lighting device is arranged, a first cross section portion for engaging with a fixing means for fixing the edge profile to the vehicle body, said first cross section portion being arranged at a back portion of the profile body that faces the vehicle body, a flat upper support portion on top of the first cross section portion for supporting a top plate of the superstructure, and a plate-shaped flange portion extending vertically at the bottom of the profile body.
This edge profile according to the present invention combines a number of different functions. First of all, the first band-shaped lighting device serves to illuminate the border of the top plate of the superstructure, i. e. the deck at the top of the vehicle. The edge of this deck is supported by the flat upper support portion. Because the top plate is completely enclosed and supported by the edge profile, no welding is necessary at the edges, and it is possible to combine a top plate of a different material with the present edge profile. The environment of the vehicle is illuminated by the second band-shaped lighting device that radiates light in a lateral downward direction to illuminate a ground around the vehicle. The first cross section portion forms an engaging and fixing portion of the profile to engage with a fixing means of the vehicle body that can be inserted into the first cross section portion. Finally the plate shaped flange portion serves to cover the upper part of a storage compartment at the side of the vehicle, especially to cover a roller shutter. Moreover, this flange portion can carry a visual marking that extends around the top of the vehicle.
According to one preferred embodiment of the present invention, at least one of the first and second band-shaped lighting devices is a lighting bar that is fixed within the respective first or second groove. Such a lighting bar can be made of a transparent or translucent plastic material housing a number of small light sources, for example, LEDs. Each lighting bar can be fixed in its respective groove by any suitable means, also including the option that the lighting bar is simply fixed into the groove by a snap-fit action.
More preferably the first cross section portion for engaging with a fixing means comprises a third groove opening towards the back side of the profile body. This third groove can accommodate a corresponding tongue or other protrusion fixed to the vehicle body.
According to another preferred embodiment of the present invention, the cross section of the extruded profile body further comprises a second cross section portion for engaging with a fixing means for fixing the edge profile to the vehicle body, said second cross section portion comprising a fourth groove opening towards the bottom side of the profile body and being arranged below the first cross section portion at the back portion of the profile body. This second cross section portion provides other options to fix the edge profile to the vehicle body.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment described hereinafter.
FIG. 1 is a cross section through one embodiment of an edge profile body according to the present invention; and
FIG. 2 is a perspective view of the edge profile comprising the edge profile body from FIG. 1 in its mounted position fixed to the superstructure of a vehicle body.
DETAILED DESCRIPTION OF THE INVENTION
The profile body 10 in FIG. 1 is the main structure component of the edge profile 100 in FIG. 2 for bordering the superstructure of a rescue vehicle, in particular a fire fighting vehicle. The profile body 10 is an extruded profile formed of a metal like aluminum or an aluminum alloy. The cross section of this extruded profile body 10 comprises a central hollow channel 12 that is open only to the longitudinal ends of the profile body 10 . In FIG. 1 , the back side of the edge profile 100 (or the profile body 10 ) is located at the right side of the cross section in the figure, which is the side of the edge profile to be fixed at the vehicle body. In the following description the term “back” refers to the mounting position of the edge profile as such, its back side facing the vehicle, while the term “lateral” refers to one side of the cross section of the profile body 10 , as seen in FIG. 1 . This means that the back side and front side of the edge profile are each one of the lateral sides of the cross section in the perspective of FIG. 1 .
On the top side of the profile body 10 , its cross section comprises a first groove 14 opening towards the upper side of the profile body 10 . This first groove 14 has a rectangular cross section, and the horizontal flat bottom 16 of this first groove 14 is defined by a horizontal wall portion that separates the space within the first groove 14 from the central hollow channel 12 inside the profile body 10 . The walls of this groove 14 are slightly inclined towards each other so as to constrict the free cross section of the groove 14 towards its bottom 16 . Directly above the bottom 16 of the groove 14 , an undercut 17 is formed.
At a lateral bottom portion of the cross section of the profile body 10 , a second groove 18 is located that has also a mainly rectangular cross section with a flat bottom 20 delimiting the space within the second groove 18 from the hollow channel 12 . While the cross section and shape of both first and second grooves 14 , 18 is approximately the same, including the restricting free cross section of the second groove 18 and the undercut at its bottom 20 , the bottom 20 of the second groove 18 is inclined about an angle of about 45 degrees with respect to the vertical axis. By this arrangement the cross section of the second groove 18 opens laterally downwards towards the bottom side of the profile body 10 .
At the front side of the profile body 10 , the hollow central channel 12 is closed by a front wall 22 connecting the front edge 24 of the second groove 18 with the front edge 26 of the first groove 14 , this front wall 22 being slightly bended and having an approximately vertical cross section at its bottom portion.
Both first and second grooves 14 , 18 are provided to receive a band-shaped lighting device, like it is shown in FIG. 2 . In the embodiment described here, this band-shaped lighting device is a lighting bar 28 , 30 that is fixed within the respective first or second groove 14 , 18 . This lighting bar can be made of a transparent or translucent plastic material, with a number of light sources arranged within the lighting bar. Any electric supply means like a cable, can also be housed within the lighting bar 28 , 30 or within a space below the respective lighting bar 28 , 30 and the bottom 16 , 20 of the respective first or second groove 14 , 18 . In the case of the first groove 14 , the lighting bar 28 serves to illuminate the space above the edge profile 100 and to mark a borderline encircling the superstructure of the vehicle, especially a top plate 32 that forms a deck of the vehicle. A person standing on this deck 32 can easily identify the borders of the top plate, that are visualized by the first band-shaped lighting device in form of a lighting bar 28 received within the first groove 14 .
A second lighting bar 30 forms a second band-shaped lighting device that is comprised within the second groove 18 . The shape and cross section of this second lighting bar 30 may be the same as the first lighting bar 28 , also comprising a number of light sources housed within the hollow second lighting bar 30 . Because of the inclination of the second lighting bar 30 that is arranged within the second groove 18 opening laterally towards the bottom side of the profile body 10 , the main radiation direction of the second lighting bar 30 is inclined downwardly in a direction away from the vehicle body for illuminating the ground area around the vehicle.
The back side of the hollow central channel 12 is formed by a back wall 34 that emerges into a vertical plate-shaped flange portion 36 protruding downwardly at the bottom of the extruded profile body 10 . The flat front side 38 of this flange portion extends from the lower (inner) edge 40 of the second groove 18 towards the bottom end 42 of the profile body 10 . This flat front surface 38 can serve as an area for applying a contour marking to improve the visibility of the superstructure of the vehicle. As an additional function, the flange portion 36 can cover the upper portion of a vehicle compartment for storing devices that are needed in a rescue situation. In particular the flange portion 36 may cover the top portion of an integrated roller shutter of such a compartment.
The top deck portion of the extruded profile body 10 further comprises a first cross section portion 44 that faces the vehicle body. This first cross section portion 44 comprises a mainly rectangular groove (also referred to as third groove) that opens towards the back of the profile body 10 , wherein the bottom 46 of this third groove is formed by a vertical upper back wall portion of the central hollow channel 12 . The walls 48 of this groove further comprise ridges 50 of a dovetail shape that protrude from these sidewalls 48 . These ridges 50 extend in the longitudinal direction of the profile body 10 so that an undercut portion 52 is formed between the ridges 50 and bottom 46 of the groove of the first cross section portion 44 . The shape of the first cross section portion 44 is such that it can engage with a corresponding fixing means at the vehicle body (not shown) for fixing the edge profile 10 to the vehicle body. For example, corresponding protrusions may extend in the longitudinal direction into the opposing open ends of the first cross section portion 44 to engage with the dovetail shaped ridges 50 or into the undercut portion 52 so as to prevent the edge profile 10 from being drawn off the vehicle body. The shape of the first cross section portion 44 can be such that it matches with fixing means of a modular system for constructing the superstructure of the rescue vehicle.
The top side of the upper sidewall portion 48 of the first cross section portion 44 forms a flat upper support portion 54 on top of the first cross section portion 44 for supporting the top plate 32 forming the deck of the superstructure, as shown in FIG. 2 . This means that this wall portion 48 has the functions to delimit the first cross section portion 44 towards the top side of the profile body 10 , on one hand, and to support the edge of the top plate 32 on the other hand. Towards the front side of the profile body 10 , the flat upper support portion 54 is delimited by a ridge 56 separating the flat upper support portion 54 from the first groove 14 .
Below the first cross section portion 44 , a second cross section portion 58 is provided that has generally the same shape in cross section as the first cross section portion 44 . This means that a second cross section portion 58 comprises a groove (also referred to as fourth groove) with a mainly rectangular shape, with a flat bottom 47 (which is arranged here at the top side of the second cross section portion 58 ) and vertical side wall portions 48 with ridges 50 that have a dovetail shape, forming an undercut 52 between the ridges 50 and the bottom 47 of the second cross section portion 58 . The second cross section portion 58 is turned around 90° with respect to the first cross section portion 44 so that the fourth groove opens towards the bottom side of the profile body 10 . The second cross section portion 58 is also provided for engaging with a fixing means (not shown) for fixing the edge profile 100 to the vehicle body, for example, a protrusion with a complementary shape engaging into the opposing open ends of the second cross section portion 48 so that it is possible to lift the edge profile 100 from its mounted position.
In the present embodiment the edge profile 100 according to the present invention combines different advantages, namely the integration of a lighting system for visualizing the borders of the top plate 32 forming the deck of the superstructure, the integration of a lighting system for illuminating the ground area around the vehicle, an area for applying a visual marking, and a closing structure for closing the top portion of a vehicle compartment below and behind the edge profile 100 . Moreover, this edge profile 100 can easily be mounted as part of a modular system by means of a first and second cross section 44 and 58 for engaging with a corresponding fixing means of this system. Furthermore it is noted that the central hollow channel 12 can be used for guiding supply means like electrical cables or hydraulic hoses. The number of parts that is necessary for mounting the edge profile 100 is reduced, which also applies to the mounting costs.
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An edge profile for bordering the superstructure of a rescue vehicle is contemplated, specifically an edge profile for bordering the upper walking deck of a firefighting vehicle that provide a modular construction system with enhanced security features. The edge profile is an extruded hollow body having a cross section with a front wall portion and an upper and lower groove for simultaneously illuminating the border of the upper walking deck and the environment around the base of the vehicle. The edge profile modularly engages with the vehicle body via cross-sectional horizontal and vertical mounting grooves, which do not require welding. A lower flange portion is further provided to cover upper parts of storage compartments at the sides of the vehicle, especially roller shutters.
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to an automatic centering method for a video camera having a plurality of pick-up tubes and, in particular, is directed to an automatic centering method suitable for use with a three pick-up tube type video camera by which the centers of picture screens of three pick-up tubes can automatically be made coincident with one another.
2. Description of the Prior Art
In the prior art, when the centering of a video camera of, for example, the three pick-up type is carried out, a predetermined test chart such as a stripe pattern and so on is picked up by the pick-up tubes and while the pictures shot by the pick-up tubes are checked by a television monitor and so on, the deflection systems and the like of the respective pick-up tubes are adjusted.
Such a prior art centering method, however, always requires the test chart and, the deflection system and so on must be adjusted very skillfully.
On the other hand, as is disclosed in a Japanese patent application No. 175427/1983 previously proposed by the present applicant, it was considered that an arbitrary object be shot by a pick-up tube and the centering thereof be carried out automatically by using a microcomputer.
In this case, however, it became clear that depending on the content of the object, the centering was not carried out correctly but the displacement among the centerings was increased.
That is, as shown in FIGS. 2A and 2B, when objects which are the same in displacement amount (shown by an arrow) but different ones are shot or picked up, in the case of FIG. 2A, the objects are converged to the nearby pattern (shown by a double arrow) to thereby establish the correct centering, while the case of FIG. 2B, when the objects are converged to the nearby pattern (shown by the double arrow), the displacement amount of the centerings is increased, on the contrary.
Accordingly, if a picture is taken by the video camera with the displaced centering, it becomes impossible to reproduce the picture correctly. As a result, the pictures taken by the video camera become useless.
OBJECTS AND SUMMARY OF THE INVENTION
Accordingly, it is an object of this invention to provide an automatic centering method for a video camera having a plurality of pick-up tubes by which centers of the picture screens thereof can be made coincident with each other automatically.
It is another object of this invention to provide an automatic centering method for a video camera having a plurality of pick-up tubes which can prevent a picture from being shot with an incorrect centering state.
According to an aspect of this invention, there is provided an automatic centering method for a video camera having a plurality of pick-up tubes and a deflection control circuit for each of said plurality of pick-up tubes comprising the steps of:
(A) comparing outputs of two pick-up tubes of said plurality of pick-up tubes to thereby generate an error signal;
(B) processing said error signal to thereby generate a control signal;
(C) supplying said control signal to said deflection control circuit for one of said two pick-up tubes;
(D) storing said control signal in a memory;
(E) changing said control signal supplied to said deflection control circuit by a predetermined amount;
(F) repeating the above-described steps (A) to (C);
(G) comparing said control signal generated in said step (F) and said control signal in said memory with each other to thereby generate an error flag signal when said control signals do not coincide with each other; and
(H) indicating said error flag signal.
These and other objects, features and advantages of the present invention will become apparent from the following detailed description of the preferred embodiment taken in conjunction with the accompanying drawings, throughout which like reference numerals designate like elements and parts.
BRIEF DESCRIPTION IN THE DRAWINGS
FIG. 1 is a block diagram showing an example of an automatic centering apparatus which is used to carry out an embodiment of the automatic centering method for a video camera according to this invention;
FIGS. 2A and 2B are respectively diagrams useful for explaining the effect of this invention;
FIG. 3 is a flow chart useful for explaining the operation of the automatic centering apparatus of FIG. 1;
FIGS. 4A, 4B, FIGS. 5A, 5B and FIGS. 6A, 6B are respectively diagrams useful for explaining the flow chart of FIG. 3;
FIG. 7 is a diagram of an example of a picture displayed on a picture screen of a display apparatus useful for explaining this invention; and
FIG. 8 is a diagram showing an example of a memory area of a microcomputer used in this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 is a block diagram schematically showing an example of the automatic centering apparatus for a video camera which can carry out an embodiment of the automatic centering method for a video camera according to this invention.
In FIG. 1, reference numeral 1 designated a video processing circuit which delivers therefrom red (R), green (G) and blue (B) video signals from, for example, three pick-up tubes (not shown) and which produces edge signals (differentiation signals) H GP and V GP of horizontal and vertical directions of a picture image of, for example, green color which is taken as a reference in the centering.
The reference green video signal from the video processing circuit 1 is supplied to an inverted input terminal of a differential amplifier 2 and the red and blue video signals R and B from this video processing circuit 1 are selected by a switch 3. Further, the selected signal R or B and the green video signal G are selected by a switch 4 and then the selected video signal is fed to a non-inverting input terminal of the differential amplifier 2.
The output signal of the differential amplifier 2 is supplied to a multiplier 5 and the edge signals H GP and V GP from the video processing circuit 1 are selected by a switch 6 and then the selected signal is fed to the multiplying circuit 5.
The output signal from this multiplying circuit 5 is supplied to a sample and hold circuit 7 and the selected signal from the switch 6 is supplied through a full-wave rectifying circuit 8 to the sampling terminal of the sample and hold circuit 7.
The output signal (potential V E ) of the sample and hold circuit 7 is supplied to a negative input terminal of a potential comparing circuit 9.
An output data of a microcomputer 10 is supplied to a D/A (digital-to-analog)-converting circuit 11 and an analog signal (potential) thus converted by the D/A-converting circuit 11 is supplied to the positive input terminal of the voltage comparing circuit 9. As a result, when the inputs applied to the positive and negative input terminals of the comparing circuit 9 coincide with each other, the output signal from the comparing circuit 9 is supplied to the microcomputer 10 in which the output data from the comparing circuit 9 is latched as a digital value of the potential V E .
Further, the output signal from the D/A-converting circuit 11 is supplied to a plurality of sample and hold circuit groups 12 and these sample and hold circuit groups 12 are operated by the control signal from the microcomputer 10 to thereby hold therein respective desired potentials.
The held potentials in the sample and hold circuit groups 12 are supplied to a deflecting system 13 of the three pick-up tubes (not shown).
The switches 3, 4 and 6 are respectively controlled by the control signal from the microcomputer 10. The output data from the microcomputer 10 is supplied to a display apparatus 14.
A switch 15 is connected to a starting terminal of the microcomputer 10 and when this switch 15 is depressed or turned on, the microcomputer 10 starts its automatic centering mode.
FIG. 3 illustrates a flow chart of the software stored in the microcomputer 10. The flow chart of FIG. 3 is for the case where the position of the red picture in the horizontal direction is made coincident with the reference green picture, but the cases where the position of the red picture in the vertical direction and positions of the blue picture in the horizontal and vertical directions are made coincident with the reference green picture are substantially similar to that of FIG. 3. In the initial state, in the memory (random access memory) of the microcomputer 10, there is stored a value corresponding to a standard deflection position in the horizontal (H) and vertical (V) directions of the red (R) and blue (B) pictures, for example, a value "80" if the memory is an 8-bit memory which can take values from "00" to "FF". This value "80" is produced from the microcomputer 10 and then fed to the deflecting system 13.
Referring to FIG. 3, when the centering operation is started, in step 1, the switch 4 is changed in position to the side of the green video signal G and the switch 6 is changed in position to the side of the edge signal H GP respectively so that the potential V E produced from the voltage comparing circuit 9 is expressed as
V.sub.E =(G-G)×H.sub.GP
Then, this potential V E is A/D (analog-to-digital)-converted and then written in a reference potential memory area (RF) of the microcomputer 10 (refer to FIG. 8).
In next step 2, a flag (1st FLG) indicative of the first processing of the centering operation is written or set in the memory area of the microcomputer 10.
In the following step 3, the switch 3 is changed in position to the side of the red video signal R and the switch 4 is changed in position to the side of the switch 3 respectively so that the potential V E from the voltage comparing circuit 9 is expressed as
V.sub.E =(R-G)×H.sub.GP
Then, this potential V E is A/D-converted similarly as mentioned above and then stored in a compared input memory area (AD) of the microcomputer 10.
The potential stored in the memory area (AD) of the microcomputer 10 corresponds to the phase displacement (centering displacement) between, for example, the green and red video signals G and R and has the characteristic in accordance with the state of objects as shown in FIGS. 4A, 4B to FIGS. 6A, 6B.
That is, when the content of the object is of such a pattern that longitudinal stripes of enough width are arranged with a proper spacing or distance between adjacent ones as shown in FIG. 4A, the potential is changed monotonically as shown in FIG. 4B. In this case, when the potential becomes equal to "0" (=value of RF), the condition in which centering has been exactly performed is established.
On the other hand, when the width of each of the longitudinal stripes is small as shown in FIG. 5A, the potential is changed in the form of substantially S-shape as shown in FIG. 5B so that the both sides of the potential become equal to "0". In this case, AD="0" at the center of the S-shape indicates the correct centering position and the both sides thereof indicate the incorrect centering positions.
When the width of each of the stripes is narrow and the distance between the adjacent strips is also narrow as shown in FIG. 6A, the potential is changed in the form of a triangular wave shape a shown in FIG. 6B. In this case, AD="0" is established at two places, in which one indicates the correct centering position, while the other indicates a case in which the object is focussed at the opposite side as shown in FIG. 2B.
Therefore, in step 4, it is judged whether a value expressed as (AD)-(RF)=Δ is larger than or smaller than 1 LSB (least significant bit) or not (|AD|-|RF|)=|Δ.vertline.≦1 LSB. This value Δ is utilized as error data.
In step 4, if it is judged that Δ≦±1 LSB is established, in next step 5, ±1 LSB is added to the data stored in the memory area (MA01) corresponding to the horizontal deflection position of the red picture in accordance with the polarity of Δ and this data is once again stored in the memory area (MA01). Then, the value or data of the memory area (MA01) is delivered from the microcomputer 10 to the deflecting system 13. Further, the potential V E at this time is latched in the microcomputer 10 and the above-described operations are repeated in turn.
In next step 6-1, if it is judged that the polarity of Δ is changed, the processing step proceeds to step 10. While, when in step 6-1 it is judged that the polarity of Δ is not changed, the processing step proceeds to step 6-2 in which 1 LSB is added to the data in the same direction. This adding operation is continued until it is judged the this operation has been carried out 16 times in step 6-2. In step 6-2, if it is judged that the operation has been carried out 16 times, the processing proceeds to step 8.
In step 4, if it is judged that Δ>±1 is established, the step proceeds to step 7 in which the value Δ is subtracted from the data of the memory area (MA01) of the microcomputer 10 and the subtracted value is delivered from the microcomputer 10 to the deflecting system 13.
Then, the step 7 proceeds to step 8. In step 8, a reference correcting data ±k (k is an arbitrary interger) is added to the data of the memory area (MA01) in accordance with the polarity of Δ. The resultant data is returned to the memory area (MA01) of the microcomputer 10, and the value or data of the memory area (MA01) is delivered from the microcomputer 10 to the deflecting system 13. At this time, the potential V E is latched in the memory area (MA01) and this operation is carried out sequentially.
In next step 9-1, it is judged whether the polarity of Δ is changed or not. If it is judged that the polarity of Δ is changed, the processing step proceeds to step 9-3. In step 9-3, it is judged whether k=1 LSB is established or not. If it is judged that k=1 LSB is not established, the processing step proceeds to step 9-4 in which the same operation is carried out with ±1/2k instead of ±k.
In step 9-1, if it is judged that the polarity of Δ is not changed, the same addition processing of k is repeated. Then, in next step 9-2, if it is judged that the polarity of Δ is not changed after the above-described operation is carried out 16 times, the processing step proceeds to step 17.
As described above, if in step 6-1 it is judged that the polarity of Δ is changed, the processing step proceeds to step 10. In step 10, it is judged whether the first flag is set in the memory area (1st FLG) of the microcomputer 10 or not. If the flag is set in the memory area, the processing step proceeds to step 11. In step 11, the flag for the memory area (1st FLG) of the microcomputer 10 is reset.
Further, in next step 12, the value of the memory area (MA01) is stored in the memory save area (MA0SAVE) of the microcomputer 10.
In next step 13, it is judged whether the value stored in the memory area (MA01) is larger than "80" or not. If it is larger than "80", the step proceeds to step 14, in which "40" is subtracted from the data stored in the memory area (MA01). If not, the processing step proceeds to step 15 in which "40" is added to the data stored in the memory area (MA01) and the resultant data is once again returned to the memory area (MA01) of the microcomputer 10.
After the addition and subtraction as mentioned above, in next step 16, the value of data stored in the memory area (MA01) is delivered to the deflecting system 13. Thereafter, the processing step is returned to step 8.
Thereby, from the state that the convergence of the first centering is carried out, the convergence operation of step 8 once again begins with the position at which the adjustment range of the centering is displaced by one half.
As set forth above, in step 9-2, if it is judged that the polarity of Δ is not changed after the same operation is carried out 16 times, the processing step proceeds to step 17. In step 17, it is judged whether the flag (1st FLG) is written in the memory area of the microcomputer 10 or not.
In step 17, if it is judged that the flag is written the therein, the convergence of the centering is not completed by the first operation so that "NG" is indicated on the picture screen of the display apparatus 14 in next step 18 and the convergence operation is stopped.
If the flag is reset, it is judged that the state of the centering is as shown in FIGS. 4A and 4B or FIGS. 5A and 5B so that in next step 19, the data of the memory area (MA0SAVE) is written in the memory area (MA01) of the microcomputer 10. Then, the data stored in the memory area (MA01) is delivered from the microcomputer 10 to the deflecting system 13.
Then, in next step 20, "OK" is indicated on the picture screen of the display apparatus 14 and the convergence operation is stopped.
Further, as described above, in step 9-3, if it is judged that k=1 LSB is established, the processing step proceeds to step 10. In step 10, since the first flag (1st FLG) is reset, the processing step proceeds to step 21. In step 21, it is judged whether the data stored in the memory area (MA0SAVE) coincide with each other or not.
If they are coincident with each other, the processing step proceeds to step 20, in which "OK" is indicated on the picture screen of the picture display apparatus 14.
If not, this is regarded as the state shown in FIGS. 6A and 6B and in next step 22, "NG" is indicated on the picture screen of the display apparatus 14 and the convergence operation is ceased.
As described above, the adjustment of the centering is carried out. According to the automatic centering method of this invention, when the object is inappropriate as shown in FIGS. 6A and 6B, even if the convergence operation is carried out, "NG" is indicated on the picture screen of the display apparatus 14. Thus, there is no fear that the picture will be taken uselessly by the video camera with incorrect centering.
In this case, when the contents of the object are changed by a so-called zoom-up technique or the like, the correct centering can be made. Therefore, in the indication of step 22, as, for example, shown in FIG. 7, in addition to "CENT NG", "OBJECT ?", "TRY AGAIN" and so on are indicated on the picture screen of the display apparatus 14, while only "CENT NG" is indicated in step 18.
While in the above operation the position of the red color picture in the horizontal direction is made coincident with the reference green color picture, the position of the red color picture in the vertical direction and positions of the blue color picture in the horizontal and vertical directions can be made coincident with the reference green color picture by substantially similar manner. In that case, as shown in FIG. 8, if in addition to the memory area (MA01), other memory areas (MA01) to (MA04) are respectively provided in the microcomputer 10 and in steps 1 and 3 shown in the flow chart of FIG. 3, the switch 6 is changed in position to the side of the edge signal V GP or the switch 3 is changed in position to the side of the blue video signal B, the convergence of each centering of these can be carried out. Also in these cases, even if the convergence operation of the centering is carried out with the inappropriate object similar to that mentioned above, the "NG" indication for such inappropriate object can be carried out.
As set forth above, according to this invention, it becomes possible to positvely prevent the picture from being taken by the video camera under the state that the centering thereof is incorrect.
The above description is given on a single preferred embodiment of the invention, but it will be apparent that many modifications and variations could be effected by one skilled in the art without departing from the spirits or scope of the novel concepts of the invention, so that the scope of the invention should be determined by the appended claims only.
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An automatic centering method for a video camera having a plurality of pick-up tubes and a deflection control circuit for each of the plurality of pick-up tubes is disclosed, which includes the steps of comparing outputs of two pick-up tubes of the plurality of pick-up tubes to thereby generate an error signal, processing the error signal to thereby generate a control signal, supplying the control signal to the deflection control circuit for one of the two pick-up tubes, storing the control signal in a memory, changing the control signal supplied to the deflection control circuit by a predetermined amount, repeating the above-described first to third steps, comparing the control signal generated in the sixth step and the control signal in the memory with each other to thereby generate an error flag signal when the above two control signals do not coincide with each other and indicating the error flag signal.
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