An exhaust purifying system includes switching between a stratified combustion state at a stratified combustion region (I) of low revolutions speeds and low loads and a homogeneous combustion state of substantially the theoretical air/fuel ratio at a warm xcex=1 region (II) adjacent thereto with higher revolution speeds or loads, wherein a first oxygen concentration sensor is arranged upstream from the three-way catalyst, and when an engine shifts from the stratified combustion region (I) to the warm xcex=1 region (II), the feedback control of the air/fuel ratio based on an output signal of that sensor begins, and the target air/fuel ratio A/F is set to a range of 14.0xe2x89xa6A/F less than 14.7, so that the target air/fuel ratio A/E is slightly richer than the theoretical air/fuel ratio, thus preventing a temporary deterioration of the exhaust gas state.

The present invention relates to exhaust gas purifying systems for engines, which are provided with a catalyst displaying a three-way purification function when at least the exhaust gas is in a state corresponding substantially to a theoretical air/fuel ratio, and in which the engine is ordinarily switched between an operating state in which the air/fuel ratio in the combustion chamber is lean and an operating state in which it is substantially at the theoretical air/fuel ratio or richer than that.
Conventionally, as exhaust gas purifying systems for this kind of engine, systems are known, in which a so-called three-way catalyst is arranged in the exhaust duct of the engine, and an NOx absorbing/reducing catalyst including an NOx absorbing material is arranged nearby on the downstream side, as disclosed for example in Japanese Laid-Open Patent Publication (Tokkai) No. 11-200853. For the NOx absorbing material, it is possible to use, for example, an alkaline earth metal such as barium, and when the air/fuel ratio of the exhaust gas is in a predetermined lean state, that is, in an oxygen-rich atmosphere with an oxygen concentration of, for example, at least 4% in the exhaust gas, the NOx in the exhaust gas is oxidized, and absorbed as nitrate, whereas when the oxygen concentration drops, the absorbed nitrate undergoes a substitution reaction with the CO in the exhaust gas, and NOx is released, while the CO is absorbed as carbonate.
When the air/fuel ratio of the exhaust gas is in the lean state, the NOx in the exhaust gas is absorbed by the above-mentioned NOx absorbing material, and the exhaust gas is purified. Furthermore, when the engine is operated substantially at the theoretical air/fuel ratio, and the air/fuel ratio of the exhaust gas is in a state corresponding substantially to the theoretical air/fuel ratio, that is, when the oxygen concentration is about 0.5 to 1% or lower, almost all of the HC, CO and NOx in the exhaust gas is purged due to the three-way purification function of the catalyst, and the NOx released from the NOx absorbing material reacts with the HC and CO, and reduction purification is performed.
Moreover, the NOx absorbing material has the property that, as the amount of absorbed NOx increases, the ability of the NOx absorbing material to absorb NOx decreases, so that in the above conventional example, when the engine shifts from an operating state with a lean air/fuel ratio to an operating state at substantially the theoretical air/fuel ratio, the air/fuel ratio is enriched considerably for a short time, that is, in spike-form, thus promoting the release of NOx.
Like the NOx absorbing/reducing catalyst, the so-called three-way catalyst, which displays a three-way purification function when the air/fuel ratio of the exhaust gas is in a state corresponding substantially to the theoretical air/fuel ratio, generally includes an oxygen absorbing material, such as ceria (CeO2). This oxygen absorbing material has the property that it absorbs oxygen in the exhaust gas when the oxygen concentration is larger than a certain level (for example 0.5%), and releases oxygen when the oxygen concentration is lower than that value, so that the variations of the oxygen concentration in the exhaust gas are dampened, and the three-way purification function can be increased.
However, when a three-way catalyst and an NOx absorbing/reducing catalyst are arranged in series in the exhaust duct of the engine, as in the above conventional example, and the air/fuel ratio of the exhaust gas is changed from a lean state to a state corresponding substantially to the theoretical air/fuel ratio, then oxygen is released from the oxygen absorbing material included in the catalysts, so that the air/fuel ratio shifts locally toward the lean side in the vicinity of the two catalysts, and the HC and CO in the exhaust gas are used up by reacting with the oxygen, and eventually it becomes impossible to release NOx efficiently from the NOx absorbing/reducing catalyst located downstream.
Regarding this aspect, the above conventional example estimates the amount of oxygen released by the three-way catalyst by considering the operation history of the engine and the oxygen absorbing capability in the three-way catalyst, anticipates that HC or CO are consumed by reacting with the oxygen, and enriches the air/fuel ratio in the combustion chamber considerably so that a sufficient amount of HC and Co are supplied to the downstream NOx absorbing/reducing catalyst.
However, in the above-described conventional exhaust gas purifying system, when the air/fuel ratio in the combustion chamber of the engine is switched from the lean state to the state of substantially the theoretical air/fuel ratio, the amount of injected fuel increases spike-like for a short time, enriching the air/fuel ratio considerably, so that as described above, even when increasing the HC and CO in the exhaust gas to match the amount of oxygen released by the catalyst, in actuality, a lot of the HC and CO are blown through the catalyst and are emitted into the atmosphere.
Thus, the HC and CO emitted into the atmosphere increases sharply, even if only temporarily, and the condition of the exhaust gas deteriorates. Moreover, the oxygen released by the catalysts may not react sufficiently with the HC and CO, whereby in the vicinity of the catalysts, the air/fuel ratio of the exhaust gas shifts to the leaner side, leaving the appropriate air/fuel ratio range for displaying the three-way purification function, and there is the risk that the catalysts"" property of purifying the exhaust gas drops.
Therefore, with the foregoing in mind, it is an object of the present invention to provide an exhaust gas purifying system for an engine, in which a catalyst having a three-way purification function is provided in an exhaust duct, and in which the engine is usually switched between an operating state of lean air/fuel ratio and an operating state with an air/fuel ratio of substantially the theoretical air/fuel ratio or richer than that, wherein a temporary deterioration of the state of the exhaust gas caused by emission of oxygen from the catalyst can be prevented, while suppressing deterioration of the total fuel efficiency when considered for all operating regions.
In order to attain these objects, when the engine has shifted from an operating state with lean air/fuel ratio to an operating state with richer air/fuel ratio, the control target value of the air/fuel ratio is corrected to be slightly richer than the theoretical air/fuel ratio, so as to match the resulting enrichment of the air/fuel ratio with the pace in which oxygen is released from the catalyst.
More specifically, in accordance with a first aspect of the present invention, an exhaust gas purifying system for an engine includes a catalyst displaying a three-way purification function when an air/fuel ratio state of at least an exhaust gas corresponds substantially to a theoretical air/fuel ratio; a first air/fuel ratio control means for controlling an air/fuel ratio in a combustion chamber of the engine by switching to either a state that is leaner than the theoretical air/fuel ratio or a state that is richer than that, depending on the operating state of the engine; and an air/fuel ratio correction means for correcting the air/fuel ratio in the combustion chamber temporarily to a state that is even richer, when the first air/fuel ratio control means switches the air/fuel ratio in the combustion chamber from a lean state to a richer state. When the air/fuel ratio in the combustion chamber has been switched from a lean state to a richer state, the air/fuel ratio correction means sets the air/fuel ratio in the combustion chamber to a state that is slightly richer than the theoretical air/fuel ratio, so as to match a release of oxygen from the catalyst.
With this configuration, first, when the engine is in an operating state with lean air/fuel ratio, the exhaust gas from the engine is in a state of high oxygen concentration, so that a portion of the oxygen in the exhaust gas is gradually absorbed by the catalyst. Then, when the operating state of the engine changes and the air/fuel ratio in the combustion chamber is switched by the first air/fuel ratio control means to a state in which the air/fuel ratio is richer than in the lean state, the air/fuel ratio in the combustion chamber is temporarily corrected to an even richer state by the air/fuel ratio correction means.
In this situation, the air/fuel ratio in the combustion chamber is corrected by the air/fuel ratio correction means to a state that is slightly richer than the theoretical air/fuel ratio so as to match the release of oxygen from the catalyst, so that the air/fuel ratio state of the exhaust gas from the combustion chamber of the engine becomes a state of a slightly richer (lower) oxygen concentration than in the state corresponding to the theoretical air/fuel ratio. This cancels the influence of the oxygen release from the catalyst, thus maintaining the local air/fuel ratio state in the vicinity of the catalyst in a state corresponding to substantially the theoretical air/fuel ratio. Thus, the three-way purification performance of the catalyst can be maintained reliably. Moreover, there is no spike-like enrichment of the air/fuel ratio state of the exhaust gas as in the related art (JP H11-200853), so that HC and CO in the exhaust gas are not blown through the catalyst.
The exhaust gas purifying system for an engine according to a second aspect of the present invention further includes a detection means for detecting concentration of a predetermined component of the exhaust gas upstream from the catalyst. Furthermore, the first air/fuel ratio control means controls the air/fuel ratio in the combustion chamber to a state that is leaner than the theoretical air/fuel ratio when the engine is in a predetermined operating region of low revolution speeds and low loads, and feedback controls the air/fuel ratio in the combustion chamber to a target value A/F near the theoretical air/fuel ratio, based on a signal from the detection means, when the engine is in a preset operating region of higher revolution speeds and/or higher loads than that predetermined operating region. Additionally, when the engine has shifted from the predetermined operating region to the preset operating region, the air/fuel ratio correction means sets the target value A/F of the air/fuel ratio feedback control with the first air/fuel ratio control means within a range of 14.0xe2x89xa6A/F less than 14.7, until a predetermined air/fuel ratio correction period has passed.
With this aspect of the present invention, first, the air/fuel ratio control means controls the air/fuel ratio in the combustion chamber to a state that is leaner than the theoretical air/fuel ratio when the engine is in a predetermined operating region of low revolution speeds and low loads. In this situation, the exhaust gas is in a state of high oxygen concentration, so that a portion of the oxygen in the exhaust gas is gradually absorbed by the catalyst. Then, when the engine shifts from the predetermined operating region to the preset operating region, the air/fuel ratio correction means sets the target value A/F of the air/fuel ratio feedback control with the first air/fuel ratio control means within a range of at least 14.0 and less than 14.7, that is, slightly richer than the theoretical air/fuel ratio, until a predetermined air/fuel ratio correction period has passed.
Thus, the air/fuel ratio state of the exhaust gas becomes slightly richer than in the state corresponding to the theoretical air/fuel ratio, that is, a state in which the oxygen concentration is low, and this drop of the oxygen concentration cancels the influence of the oxygen release by the catalyst, so that the local air/fuel ratio state in the vicinity of the catalyst is maintained in a state corresponding substantially to the theoretical air/fuel ratio. Moreover, the state of the air/fuel ratio of the exhaust gas is not enriched spike-like, so that the HC and CO in the exhaust gas are not blown through the catalyst.
That is to say, the oxygen released from the catalyst is reacted in just the right amount with the HC and CO in the exhaust gas, preventing a deterioration of the state of the exhaust gas due to blowing through of HC or CO, and maintaining a stable three-way purification performance of the catalyst.
The exhaust gas purifying system for an engine according to a third aspect of the present invention further includes a detection means for detecting concentration of a predetermined component of the exhaust gas upstream from the catalyst. Furthermore, the first air/fuel ratio control means basically controls the air/fuel ratio in the combustion chamber to a state that is leaner than the theoretical air/fuel ratio when the engine is in a predetermined operating region of low revolution speeds and low loads, and feedback controls the air/fuel ratio in the combustion chamber to a target value A/F near the theoretical air/fuel ratio, based on a signal from the detection means, when the engine has entered a preset specified operating state in the predetermined operating region. Moreover, when the engine has entered the specified operating state in the predetermined operating region, the air/fuel ratio correction means sets the target value A/F of the air/fuel ratio feedback control with the air/fuel ratio control means within a range of 14.0xe2x89xa6A/F less than 14.7, until a predetermined air/fuel ratio correction period has passed.
Thus, when the engine has entered a specified operating state in the predetermined operating region with low revolution speeds and low loads, that is, when for example the engine has shifted from a normal operating state to an accelerating operating state, a similar operational effect as in the second aspect of the present invention can be attained.
The exhaust gas purifying system for an engine according to a fourth aspect of the present invention further includes an oxygen absorption amount estimation means for estimating the amount of oxygen absorbed by catalyst when the engine is in the predetermined operating region, and a correction period setting means for setting a length of the air/fuel ratio correction period in accordance with a value estimated by the oxygen absorption amount estimation means.
Thus, the length of the air/fuel ratio correction period is modified by the correction period setting means in accordance with the amount of oxygen absorbed by the catalyst, so that, for example, when the engine has shifted from the predetermined operating region to the preset operating region, the air/fuel ratio state of the exhaust gas is suitably enriched continuously while oxygen is being released from the catalyst, thereby sufficiently attaining the operational effects of the first to third aspects of the present invention.
According to the fifth aspect of the present invention, the exhaust gas purifying system for an engine according to the fourth aspect of the present invention further includes a correction prohibiting means for prohibiting corrective control of the air/fuel ratio with the air/fuel ratio correction means when the value estimated by the oxygen absorption amount estimation means is not greater than a predetermined value.
Thus, when the amount of oxygen absorbed by the catalyst is not greater than a predetermined value and very small, the amount of oxygen released by the catalyst is very small too, so that in this situation, its adverse effect is very small, and improvement of the fuel efficiency can be better attained by not performing a correction of the air/fuel ratio to the richer side.
In the exhaust gas purifying system for an engine according to a sixth aspect of the present invention, the catalyst is an NOx catalyst including an NOx absorbing material that absorbs NOx in the exhaust gas in an oxygen-rich atmosphere, and releases absorbed NOx when the oxygen concentration has dropped.
Thus, when the engine is in a predetermined operating region, and the air/fuel ratio in the combustion chamber is in a state that is leaner than the theoretical air/fuel ratio, the NOx in the exhaust gas of the oxygen-rich atmosphere is absorbed by the NOx absorbing material, and the exhaust gas is purified. Furthermore, if the engine is in a preset operating region, and the air/fuel ratio in the combustion chamber is substantially the theoretical air/fuel ratio, then the NOx is released by the NOx absorbing material, but this NOx reacts with the HC and the CO in the exhaust gas, and is reduction purified.
According to the seventh aspect of the present invention, in the exhaust gas purifying system for an engine according to a sixth aspect of the present invention, a three-way catalyst is arranged in an exhaust duct upstream from the NOx catalyst, an oxygen concentration sensor for detecting oxygen concentration in the exhaust gas is arranged in the exhaust duct between the two catalysts, and the air/fuel ratio correction period is the period until the oxygen concentration detected by the oxygen concentration sensor has dropped to a preset value or lower.
That is to say, if a three-way catalyst and an NOx catalyst are arranged in order from the upstream side in the exhaust duct of the engine, then, when the air/fuel ratio in the combustion chamber of the engine shifts from a lean state to substantially the theoretical air/fuel ratio, there is the risk that the release and reduction purification of the NOx from the NOx absorbing material in the downstream NOx catalyst is impeded by the release of oxygen from the upstream three-way catalyst.
With the present invention, on the other hand, an oxygen concentration sensor is arranged downstream from the three-way catalyst, and until it is detected by the output of this oxygen concentration sensor that the oxygen concentration in the exhaust gas has dropped to or below a predetermined value, the correction to the rich side of the air/fuel ratio is continued. Thus, while oxygen is actually released from the three-way catalyst on the upstream side in the exhaust duct, the air/fuel ratio in the combustion chamber is enriched accordingly, and when no more oxygen is released from the three-way catalyst, the enriching correction of the air/fuel ratio is terminated. Thus, the adverse effect due to the oxygen release from the three-way catalyst is eliminated, and the release and reduction purification of NOx from the NOx absorbing material in the downstream NOx catalyst is suitably promoted.
In the exhaust gas purifying system for an engine according to an eighth aspect of the present invention, the catalyst is a three-way catalyst, the exhaust gas purifying system further includes a detection means for detecting concentration of a predetermined component of the exhaust gas upstream from the three-way catalyst, and an NOx catalyst having an NOx absorbing material that absorbs NOx in the exhaust gas in an oxygen-rich atmosphere and releases absorbed NOx when the oxygen concentration drops is arranged in an exhaust duct downstream from the three-way catalyst. Furthermore, an oxygen concentration sensor for detecting oxygen concentration in the exhaust gas is arranged in the exhaust duct between the three-way catalyst and the NOx catalyst. The first air/fuel ratio control means controls the air/fuel ratio in the combustion chamber to a state that is leaner than the theoretical air/fuel ratio when the engine is in a predetermined operating region of low revolution speeds and low loads, and controls the air/fuel ratio in the combustion chamber to substantially the theoretical air/fuel ratio, when the engine is in a preset operating region of higher revolution speeds and/or higher loads than that predetermined operating region. When the engine has shifted from the predetermined operating region to the preset operating region, the air/fuel ratio correction means corrects the target value of the air/fuel ratio control with the first air/fuel ratio control means to be richer than the theoretical air/fuel ratio, based on a signal from the oxygen concentration sensor, until a predetermined air/fuel ratio correction period has passed.
Thus, as in the second aspect of the present invention, when the engine has shifted to a preset region from a predetermined operating region with low revolution speeds and low loads, the air/fuel ratio correction means corrects the air/fuel ratio in the combustion chamber to a state that is slightly richer than the theoretical air/fuel ratio, canceling the release of oxygen from the three-way catalyst on the upstream side of the exhaust duct, so that the air/fuel ratio state of the exhaust gas in the vicinity of the three-way catalyst and the NOx catalyst is maintained at a suitable state that is obtained by the three-way purification function, and the release and reduction purification of the NOx from the NOx absorbing material in the NOx catalyst is suitably promoted, while preventing a deterioration of the exhaust gas state.
Moreover, in this situation, the oxygen concentration sensor is arranged between the three-way catalyst and the NOx catalyst, and based on the output from this oxygen concentration sensor, the air/fuel ratio correction means corrects the air/fuel ratio towards the richer side, so that the air/fuel ratio is suitably corrected in accordance with the release condition of the oxygen from the three-way catalyst.
In the exhaust gas purifying system for an engine according to a ninth aspect of the present invention, the catalyst is a three-way catalyst, the exhaust gas purifying system further including a detection means for detecting concentration of a predetermined component of the exhaust gas upstream from the three-way catalyst, and an NOx catalyst having an NOx absorbing material that absorbs NOx in the exhaust gas in an oxygen-rich atmosphere, and releases absorbed NOx when the oxygen concentration drops is arranged in an exhaust duct downstream from the three-way catalyst. Furthermore, an oxygen concentration sensor for detecting oxygen concentration in the exhaust gas is arranged in the exhaust duct between the three-way catalyst and the NOx catalyst. Also, the first air/fuel ratio control means basically controls the air/fuel ratio in the combustion chamber to a state that is leaner than the theoretical air/fuel ratio when the engine is in a predetermined operating region of low revolution speeds and low loads, and switches the air/fuel ratio in the combustion chamber to substantially the theoretical air/fuel ratio, when the engine enters a preset specified operating state in the predetermined operating region. When the engine enters the specified operating state in the predetermined operating region, the air/fuel ratio correction means corrects the target value of the air/fuel ratio control with the first air/fuel ratio control means to be richer than the theoretical air/fuel ratio, based on a signal from the oxygen concentration means, until a predetermined air/fuel ratio correction period has passed.
Thus, when the engine has entered a specified operating state in the predetermined operating region of low revolution speeds and low loads, that is, when for example the engine has shifted from a normal operating state to an accelerating operating state, or when the oxygen concentration in the exhaust gas is intentionally decreased in order to release and reduction purify NOx from the NOx absorbing material of the NOx catalyst, a similar operational effect as in the eighth aspect of the present invention can be attained.
According to the tenth aspect of the present invention, in the exhaust gas purifying system for an engine according to a eighth or ninth aspect of the present invention, the air/fuel ratio correction means is configured so as to terminate the correction control of the air/fuel ratio when the oxygen concentration in the exhaust gas detected by the oxygen concentration sensor has dropped to a preset value or lower.
Thus, while oxygen is actually released from the three-way catalyst, it is possible to reliably continue the correction of the air/fuel ratio accordingly.
Furthermore, the exhaust gas purifying system for an engine according to any of the eleventh to sixteenth aspect of the present invention focuses on the fact that in particular when the engine is installed in a vehicle, under regular operating conditions, the frequency in which the engine is in a rich operating state near the theoretical air/fuel ratio is relatively low, and in this regular condition, the target value of the air/fuel ratio near the theoretical air/fuel ratio is set to a value that is relatively richer than outside the regular condition, that is under a predetermined condition.
That is to say, in the exhaust gas purifying system for an engine according to a eleventh aspect of the present invention, a detection means for detecting concentration of a predetermined component of the exhaust gas is arranged in an exhaust duct upstream from the three-way catalyst, the first air/fuel ratio control means controls the air/fuel ratio in the combustion chamber to a state that is leaner than the theoretical air/fuel ratio when the engine is in a predetermined operating region of low revolution speeds and low loads, and feedback controls the air/fuel ratio in the combustion chamber to a target value near the theoretical air/fuel ratio, based on a signal from the detection means, when the engine is in a preset operating region of higher revolution speeds and/or higher loads than that predetermined operating region, furthermore the exhaust gas purifying system is further provided with a second air/fuel ratio control means, which prohibits control with the first air/fuel ratio control means under a predetermined condition and when the engine is in the predetermined operating region or the preset operating region, and feedback-controls the air/fuel ratio in the combustion chamber to a target value near the theoretical air/fuel ratio, based on the signal from the detection means. The target value for feedback control of the air/fuel ratio with the first air/fuel ratio control means is set to a value that is richer than the control target value of the second air/fuel ratio control means.
Thus, under regular conditions, when the engine is in the predetermined operating region of low revolution speeds and low loads, the first air/fuel ratio control means controls the air/fuel ratio in the combustion chamber to a state that is leaner than the theoretical air/fuel ratio.
In this situation, the air/fuel ratio state of the exhaust gas is in a state of high oxygen concentration, so that the oxygen in the exhaust gas is absorbed by the catalyst.
Then, when the engine shifts to a preset operating region, the first air/fuel ratio control means feedback controls the air/fuel ratio in the combustion chamber to a target value near the theoretical air/fuel ratio. In this situation, also the air/fuel ratio state of the exhaust gas corresponds to substantially the theoretical air/fuel ratio, so that oxygen is released from the catalyst, but the target value of the air/fuel ratio feedback control is set to be accordingly richer, so that the air/fuel ratio state near the catalyst does not deviate considerably to the leaner side, and consequently, the three-way purification function of the catalyst is not harmed. Furthermore, the air/fuel ratio of the exhaust gas is not enriched spike-like, so that the HC and CO in the exhaust gas are not blown through the catalyst.
On the other hand, under a predetermined condition, the air/fuel ratio in the combustion chamber of the engine is controlled by the second air/fuel ratio control means to substantially the theoretical air/fuel ratio or a state that is richer than that, so that in this situation, no oxygen is absorbed by the catalyst. Therefore, under this predetermined condition, when the air/fuel ratio in the combustion chamber is feedback controlled to a target value near the theoretical air/fuel ratio, the control target value can be set to a relatively leaner side, thus achieving a decrease of the fuel consumption.
That is to say, this aspect of the present invention takes advantage of the fact that under normal conditions, the engine is mostly in an operating state with lean air/fuel ratio, and rarely in an operating state at the theoretical air/fuel ratio or richer than that, and the control target value for feedback controlling the air/fuel ratio to near the theoretical air/fuel ratio is set to be slightly richer than under the predetermined condition when oxygen accumulates in the catalyst, so that the air/fuel ratio is not enriched spike-like, and the oxygen released from the catalyst can be caused to react in just the right amount with the HC and the CO in the exhaust gas. Thus, it can be prevented that a portion of the HC and CO in the exhaust gas is blown through the catalyst, and the purification performance of the catalyst can be stabilized. Furthermore, since the engine is not frequently operated near the theoretical air/fuel ratio during normal conditions, the deterioration of the total fuel consumption when regarded over the entire operating region is small, even when the air/fuel ratio at that time is set on the rich side.
According to the twelfth aspect of the present invention, in the exhaust gas purifying system for an engine according to the eleventh aspect of the present invention, the predetermined condition is that the engine is in a not-yet warmed-up state.
Thus, in the not-yet warmed-up state, in which gasification/atomization of the fuel is difficult, the air/fuel ratio in the combustion chamber is controlled by the second air/fuel ratio control means to be substantially the theoretical air/fuel ratio or in a state richer than that, regardless of the operating state of the engine, thereby ensuring combustion stability of the engine.
According to the thirteenth aspect of the present invention, the exhaust gas purifying system for an engine according to the twelfth aspect of the present invention further includes a catalyst temperature state determination means for determining whether a temperature of the catalyst is lower than a preset temperature, and a target value correction means for correcting the target value of the air/fuel ratio feedback control with the second air/fuel ratio control means to a value that is leaner than the theoretical air/fuel ratio, when the catalyst temperature state determination means has determined that the catalyst is in a low-temperature state.
Thus, even when the engine is in the not-yet warmed-up state, when the catalyst is in a not-yet activated low temperature state, the target value of the air/fuel ratio feedback control is set to be leaner than the theoretical air/fuel ratio, and by reacting the oxygen in the exhaust gas with the unburned fuel, the heating of the catalyst can be promoted. It should be noted that even when the air/fuel ratio is slightly leaner than the theoretical air/fuel ratio, the combustion stability of the engine is not harmed.
According to the fourteenth aspect of the present invention, the exhaust gas purifying system for an engine according to the eleventh aspect of the present invention is further provided with a defect state determination means for determining when at least one of the first air/fuel ratio control means and the sensors and actuators that are necessary for executing control with the first air/fuel ratio control means is defective, and the predetermined condition is that a defect has been determined by the defect state determination means.
That is to say, when the control with the first air/fuel ratio control means cannot be performed properly, the control with the first air/fuel ratio is prohibited, and the control of the air/fuel ratio is carried out with the second air/fuel ratio control means.
According to the fifteenth aspect of the present invention, in the exhaust gas purifying system for an engine according to the twelfth or fourteenth aspect of the present invention, the target value of air/fuel ratio feedback control with the second air/fuel ratio control means is substantially the theoretical air/fuel ratio.
Thus, even when the engine is in the not-yet warmed-up state or a sensor or the like is defective, the catalyst displays the three-way purification function, and a high exhaust gas purification performance can be stably ensured, while maintaining the combustion stability of the engine.
According to the sixteenth aspect of the present invention, in the exhaust gas purifying system for an engine according to the eleventh aspect of the present invention, the catalyst is a three-way catalyst, and an NOx catalyst, which includes NOx absorbing material that absorbs NOx in the exhaust gas in an oxygen-rich atmosphere, and releases absorbed NOx when the oxygen concentration drops, is provided downstream from the three-way catalyst.
With this configuration, the engine is ordinarily in the predetermined operating region with low revolution speeds and low loads, and when the air/fuel ratio in the combustion chamber is controlled to a state that is leaner than the theoretical air/fuel ratio, the air/fuel ratio state of the exhaust gas becomes a state of high oxygen concentration, and in this situation, due to the three-way catalyst on the upstream side and the NOx catalyst on the downstream side, the HC and CO in the exhaust gas are oxidized and purged, and the NOx is absorbed and eliminated. Moreover, the oxygen in the exhaust gas is absorbed by these two catalysts.
Subsequently, when the engine shifts to the preset operating region, and the air/fuel ratio in the combustion chamber is feedback controlled to a target value near the theoretical air/fuel ratio, the air/fuel ratio state of the exhaust gas becomes a state corresponding substantially to the theoretical air/fuel ratio, and in this situation, the two catalysts display a three-way purification function, and the HC, CO and NOx in the exhaust gas are purged. Then, in this situation, oxygen is released by the two catalysts, but since the target value of the air/fuel ratio feedback control has been set to a value that is accordingly richer, the air/fuel ratio state in the vicinity of the catalysts does not deviate very much, and consequently, the three-way purification function of the catalysts is not harmed. Furthermore, a suitable amount of HC and CO is supplied also to the downstream NOx catalyst, so that the release and reduction purification of the NOx from the NOx catalyst is sufficiently promote.
As explained above, with the exhaust gas purifying system for an engine according to the first aspect of the present invention, a catalyst is provided that displays a three-way purification function at least when the air/fuel ratio state of the exhaust gas corresponds substantially to the theoretical air/fuel ratio, and if the engine is switched between an operating state with lean air/fuel ratio and an operating state with an air/fuel ratio that is richer than that, when the engine has shifted from an operating state with lean air/fuel ratio to an operating state with a richer air/fuel ratio, the adverse effect due to release of oxygen from the catalyst is cancelled by correcting the target value for control of the air/fuel ratio temporarily to a slightly richer state, so that the local air/fuel ratio state in the vicinity of the catalyst can be maintained at a state corresponding substantially to the theoretical air/fuel ratio. Thus, the three-way purification function of the catalyst can be maintained stable while preventing the HC and CO in the exhaust gas from blowing through and deteriorating the exhaust gas state.
With the exhaust gas purifying system for an engine in accordance with the second or third aspect of the present invention, if the engine is switched between an operating state with lean air/fuel ratio and an operating state of substantially the theoretical air/fuel ratio, when the engine is shifted from an operating state with a lean air/fuel ratio to an operating state of substantially the theoretical air/fuel ratio, the feedback control of the air/fuel ratio begins, and the target value A/F of this feedback control is corrected to 14.0 A/F less than 14.7, thus reliably attaining the effects of the first aspect of the present invention.
According to the fourth aspect of the present invention, the period in which the air/fuel ratio is corrected to the richer side is modified in accordance with the amount of oxygen absorbed by the catalyst, so that the air/fuel ratio state of the exhaust gas can be appropriately enriched continuously while oxygen is released from the catalyst, and the effects of the first to third aspects of the invention can be sufficiently attained.
According to the fifth aspect of the present invention, an increase in fuel efficiency is attained by not performing the correction of the air/fuel ratio when the amount of oxygen absorbed by the catalyst is very small.
According to the sixth aspect of the present invention, the NOx in the exhaust gas is absorbed by the catalyst including an NOx absorbing material, even when the air/fuel ratio in the combustion chamber is in a state that is leaner than the theoretical air/fuel ratio, so that the exhaust gas can be purified.
According to the seventh aspect of the present invention, a three-way catalyst and a catalyst including an NOx absorbing material are arranged in that order from the upstream side in the exhaust duct of an engine, an oxygen concentration sensor is arranged between them, and when, based on the signal from this oxygen concentration sensor, the oxygen concentration downstream from the three-way catalyst has actually dropped, the enriching correction of the air/fuel ratio is terminated, so that the air/fuel ratio state of the exhaust gas can be suitably enriched continuously until actually no more oxygen is released from the three-way catalyst, thereby making it possible to appropriately promote the release and reduction purification of the NOx in the downstream catalyst.
With the exhaust gas purifying system according to the eighth or ninth aspect of the present invention, if a three-way catalyst and an NOx catalyst are arranged in that order from the upstream side in the exhaust duct of an engine, when the engine has shifted from an operating state with a lean air/fuel ratio to an operating state at substantially the theoretical air/fuel ratio, a sufficient exhaust gas purification performance can be attained with the two catalysts while preventing a deterioration of the exhaust gas state caused by the release of oxygen from the two catalysts, as in the second and third aspects of the present invention.
According to the tenth aspect of the present invention, in addition to the effects of the eighth and ninth aspects of the present invention, the air/fuel ratio state of the exhaust gas can be suitably enriched continuously until actually no more oxygen is released from the three-way catalyst, so that the release and reduction purification of the NOx with the NOx catalyst can be adequately promoted, as in the seventh aspect of the present invention.
Furthermore, the exhaust gas purifying system for an engine according to the eleventh aspect of the present invention includes a catalyst having a three-way purification function near the theoretical air/fuel ratio, and under normal conditions, the engine is switched between an operating state with lean air/fuel ratio and an operating state with substantially the theoretical air/fuel ratio or richer than that, whereas if under a predetermined condition, the operation with the lean air/fuel ratio is not performed, then the control target value of the air/fuel ratio under normal conditions when the engine is operated near the theoretical air/fuel ratio is set to a value that is relatively richer than under the predetermined conditions, so that the oxygen released by the catalyst in this situation is reacted in just the right amount with the HC and CO in the exhaust gas, and a temporary deterioration of the exhaust gas state caused by the release of oxygen from the catalyst can be prevented, while suppressing a deterioration of the total fuel consumption considering all operating regions.
According to the twelfth aspect of the present invention, in a not-yet warmed-up state, the air/fuel ratio in the combustion chamber is controlled to a state of substantially the theoretical air/fuel ratio or richer than that, regardless of the operating state of the engine, thus ensuring combustion stability of the engine.
According to the thirteenth aspect of the present invention, when the catalyst is not yet activated, the target value of the air/fuel ratio feedback control is set to leaner than the theoretical air/fuel ratio, thus promoting the heating of the catalyst.
According to the fourteenth aspect of the present invention, a suitable air/fuel ratio control can be performed with the second air/fuel ratio control means, even when a sensor, actuator or the like is defective, and the control cannot be performed properly with the first air/fuel ratio control means.
According to the fifteenth aspect of the present invention, a high exhaust gas purification performance of the catalyst can be reliably ensured while maintaining combustion stability of the engine, even if the engine is in a not-yet warmed-up state, or a sensor or the like is defective.
According to the sixteenth aspect of the present invention, by arranging a three-way catalyst in the exhaust duct of the engine, and arranging an NOx catalyst downstream therefrom, a high exhaust gas purification performance can be attained, regardless of the air/fuel ratio state of the exhaust gas. On the other hand, in this case, when the engine is switched from an operating state with lean air/fuel ratio to an operating state near the theoretical air/fuel ratio, the oxygen released by the upstream three-way catalyst may lead to an adverse effect on the release and reduction purification of NOx from the downstream catalyst, so that it is very advantageous that the target value of the air/fuel ratio feedback control near the theoretical air/fuel ratio is set accordingly richer, like in the first aspect of the present invention, thus canceling the influence of the oxygen release.
These and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures.


The present invention discloses a method for manufacturing alignment films for a liquid crystal display panel, characterized in that the method includes steps of: dripping liquid crystal mixture, which comprises liquid crystal molecules and liquid crystal alignment monomers, on a first substrate; gluing the first substrate and a second substrate together, irradiating the first substrate and the second substrate by a first UV ray and providing an electric field between the first substrate and the second substrate at the same time; and irradiating the first substrate and the second substrate by a second UV ray, and curing the first substrate and the second substrate at the same time to form the alignment films.

As the rapid growth of jumbo-size LCD panels and the continuous increase of the market demand for LCD (Liquid Crystal Display) televisions, there are higher requirements of processing technology and manufacture cost of LCD.
Taking an alignment film of the LCD as an example, the alignment film of the prior art is generally of a twisted nematic (TN) mode. Under the TN mode, a twisted angle of liquid crystal molecules in the LCD is 90 degree. The LCD of TN mode fails to satisfy consumers' requirement for the displaying quality of LCD due to limitations of a viewing angle and a contrast.
In a multi-domain vertical alignment (MVA) mode LCD, which has been developed in recent years, lumps are formed on a substrate with a predetermined angle, and an alignment film is further formed, so that liquid crystals are deflected to a certain angle and become static.
The formation of the alignment film having the lumps usually has to be realized by the following steps: the first step, performing irradiation; the second step, providing an electric field; the third step, performing irradiation; the fourth step, curing.
It is obvious from the above steps that at least four separate and individual implementing steps are required in the process of forming the alignment film. The process is complicated, and the efficiency is low. In addition, several platforms are required for the multiple steps, the cost is higher.

Method for manufacturing alignment films of liquid crystal display panel

Shenzhen China Star Optoelectronics Technology Co., Ltd.


Lift and slide parking systems employ a plurality of novel trolley apparatus. Each trolley includes a rectangular frame from which a platform may be raised and lowered via cables coupled to lifting bars positioned at each of four corners of the platform. On one side of the frame a slide rail and trolley sliding assembly includes hydraulic cylinders coupled with cables routed through sheaves arranged to enable movement of the trolley horizontally a necessary distance. The slide rail may include grooves in which a sliding block may be slidably retained. On the side opposite the slide rail is a lift rail and platform lift assembly which includes a hydraulic cylinder coupled with one or more belts routed through rollers to a lifting block coupled with cables routed through sheaves and coupled to lifting bars arranged to enable vertical movement of the platform. The lift rail may include grooves in which a cylinder block and lift block are slidably retained. A sliding roller at each corner of the frame is positioned to engage in tracks attached to the superstructure which run the width of the parking system.

Mechanical parking system are used where space is restricted or at a premium. The length and depth of the ground space and the height available to the system are the major factors in determining the number of vehicles that can be parked for each type of system. Just as with conventional parking systems, mechanical parking systems have space not used for parking. In the conventional system the space is needed for driving aisles, ramps, stairways and passenger elevators along with the additional space needed on each side of every parked vehicle to allow the doors to open and passengers to enter and exit. In conventional parking garages extra height is required between the levels to allow for the thickness of the floor and supporting beams, pedestrian traffic and overhead lighting. Mechanical parking garages do not require driving aisles, ramps, stairways, passenger elevators, floors, overhead lighting or pedestrian traffic. The cars can be stored much closer together because the doors are never opened in the storage area. There are no ceilings or floors required and the vertical space between the stored vehicles is kept to a minimum. Mechanical parking garages do, however, require a certain amount of equipment to perform their operation. The style and configuration of this equipment helps to determine the overall space-saving characteristic of the mechanical parking garage.


A differential with torque vectoring comprises a differential, two gear mechanisms, and two clutches. The engagement of one of the clutches and the corresponding gear mechanism provides a yaw movement in one direction or in the opposition direction. The engagement of both clutches and the corresponding gear mechanisms provides differential lock. The differential with torque vectoring can also functions as conventional open differential.

The conventional open differential of the automotive vehicles can lose traction when there is slippery condition on the surface, where the vehicles drive. Many torque vectoring designs are implemented to overcome traction loss. They are incorporated with gears and clutch to transfer and alter torque from the side gars of the differential of vehicle axles in some ways. They are less effective because such torque vectoring designs apply required additional torque to one wheel at a time, instead of applying the required additional torque to both wheels of the vehicle axles.

Differential and active torque vectoring


A re-fueling station is provided for selectively dispensing fuel in the form of liquefied gas or compressed gas. The re-fueling station comprises a storage tank for storing liquefied gas; a positive displacement fuel pump operable to draw fuel from the storage tank and discharge fuel to a flow diverter, which is operable to selectively direct fuel through one of a first outlet or a second outlet; and conduits through which fuel may flow from the first outlet to a heat exchanger and then to a first dispenser for dispensing compressed gas, or from the second outlet to a second dispenser for dispensing liquefied gas. A method is provided comprising operating the fuel pump in a low speed mode when fuel is directed to the first dispenser and operating the fuel pump in a high speed mode when fuel is directed to the second dispenser.

Natural gas has been used as a fuel for piston engine driven vehicles for over fifty years. The desire to improve efficiency and reduce pollution is causing continual change and improvements in the available technology. Some companies are also researching the use of other gaseous fuels, such as hydrogen, as a substitute for liquid fuels.
Some vehicles are designed with fuel systems that store compressed gas in pressure vessels. For example, CNG is commonly stored at ambient temperatures at pressures up to 3600 pounds per square inch (24,925 kPa). CNG can be stored at higher pressures, but this adds to the weight of the storage tanks because they need to be designed and certified for such higher pressures.
Because the energy density of liquefied gas is much greater than that of compressed gas, vehicles designed for longer range sometimes employ fuel systems that store liquefied gas at cryogenic temperatures in special thermally insulated tanks. For example, LNG is normally stored at temperatures of between about −240° F. and −175° F. (about −150° C. and −115° C.), hereinafter generally referred to as "cryogenic temperatures", and at pressures of between about 15 and 200 psig (204 and 1477 kPa). LNG storage tanks mounted on vehicles can store fuel for several days under common operating conditions. For vehicles in regular use, storing fuel at cryogenic temperatures is not a problem.
Despite the longtime use of natural gas fueled vehicles, these vehicles represent only a small fraction of the total number of vehicles currently in use and compared to the vast number of gasoline and diesel re-fueling stations, there remains a relatively small number of liquefied gas re-fueling stations. Conventional natural gas re-fueling stations are typically designed for supplying only one of LNG or CNG. When a re-fueling station is intended to serve a fleet of vehicles, the fleet can be standardized to use only LNG or only CNG. However, for re-fueling stations that are intended to serve the general public, or a plurality of commercial fleets, there is a need for a re-fueling station that can supply either LNG or CNG.
Since LNG is stored at low pressures compared to CNG, LNG re-fueling stations deliver fuel at relatively low pressures. For cryogenic fluids, centrifugal pumps are suitable for operating within the typical pressure ranges and are capable of operating with high flow rates. Centrifugal pumps designed for cryogenic fluids offer reasonable efficiency in addition to being relatively inexpensive.
Centrifugal pumps typically require fuel to be supplied to the pump suction with a positive value for the net suction head (NSH), which is defined as the difference between the pump inlet pressure and the inlet saturation pressure (expressed in terms of head). NSH is positive as long as the pump inlet pressure is greater than the inlet saturation pressure. Conversely, NSH can be negative when pump inlet pressure is less than the inlet saturation pressure.
Other LNG re-fueling stations use a pressure transfer system where vapor pressure within the LNG storage tank is controlled to provide the means for displacing the LNG from the storage tank. However, such pressure transfer systems result in extra heat being introduced into the storage tank, and may require additional equipment to prevent over-pressurization of the LNG storage tank. For example, some pressure transfer systems further comprise equipment for refrigerating and/or re-condensing vapor, and/or rely on higher quantities of gas being removed through pressure relief systems.
Another disadvantage with a pressure transfer system is that fuel delivery can be delayed since it takes time to build pressure within the storage tank.
On the other hand, CNG re-fueling stations typically employ positive displacement compressors and a cascading CNG storage system for delivering relatively high-pressure gas. Even though conventional CNG compressors operate at relatively high speeds, flow rates are typically relatively low. A cascading CNG storage system is typically used to ensure an adequate supply of high-pressure gas to fill an average-sized vehicle fuel tank in an acceptable amount of time.
The divergent operating conditions between re-fueling stations for LNG (low pressure with high mass flow rate) and CNG (high pressure with low mass flow rate) have presented a challenge for designing a simple re-fueling station capable of delivering both LNG and CNG, especially when it is desirable to have a system with only one fuel pump or compressor for quickly dispensing either LNG or CNG.
U.S. Pat. No. 5,315,831 issued 21 May 1994 (the '831 patent) discloses a combined LNG and CNG fueling station. Vapor pressure in the cryogenic tank is employed to deliver LNG to the dispenser and a natural gas fueled internal combustion engine is employed to drive a fuel pump while providing heat to a heat exchanger for producing CNG. In some embodiments, pressure within the cryogenic storage tank is relieved by bleeding gas from the storage tank into the fuel supply system for the internal combustion engine.
Accordingly, the '831 patent discloses a pressure transfer system for delivering LNG from the re-fueling station. However, as already noted, there are disadvantages associated with a pressure transfer system, such as more frequent venting from the LNG storage tank when pressure within the storage tank exceeds a predetermined maximum pressure. Venting from the LNG storage tank results in wasted natural gas.
In other arrangements, to avoid frequent venting, refrigeration equipment may be employed for re-condensing the natural gas or at least cooling the gas to collapse some of the pressure within the LNG storage tank. However, such arrangements add to the complexity of the system in addition to increased capital and operational costs.

Combined liquefied gas and compressed gas re-fueling station and method of operating same


A method of waterproofing a crimping part of a crimp terminal where a wire is crimped includes a step of forming a waterproof structure. The waterproofing structure seals a crimping region containing the crimping part with an adhesive tape. The adhesive tape has waterproofing performance and has a thickness no more than a predetermined value.

The present invention relates to a method of waterproofing a crimping part between a crimp terminal formed of copper family material to be fitted by engagement to a connecter housing and a core wire part which is exposed in an end part of a coated aluminum wire.
End parts of electric wires including a wire harness which is arranged in a vehicle are so constructed, in many cases, as to be equipped with crimp terminals to be fitted by engagement to a connecter housing, for facilitating connection between the electric wires and an apparatus.
Conventionally, as the crimp terminal to be fitted by engagement to the connector housing, a crimp terminal formed of copper family material which is excellent in resiliency and electrical conductivity has been widely used.
On the other hand, in recent years, the number of the electric wires contained in the wire harness tends to be increased with an increase of electronic apparatuses mounted on the vehicle, and so, for the purpose of making the wire harness lightweight, use of a coated aluminum wire of a type that a core wire formed of aluminum or aluminum alloy is covered with an insulating sheath has been required.
Under such circumstances, it is necessary to secure reliability of such a structure that the crimp terminal formed of copper family material is connected by crimping to the end part of the coated aluminum wire.
However, because metals of different kinds are contacted with each other in a crimping part where the crimp terminal formed of copper family material is connected by crimping to the end part of the coated aluminum wire, erosion is likely to occur when water adheres to the crimping part. Consequently, there is such anxiety that inconveniences such as faulty connection may be incurred by the erosion in the crimping part.
Therefore, the crimping part between the coated aluminum wire and the crimp terminal formed of copper family material must be designed as a waterproofing structure for preventing adhesion of water.
Heretofore, as the method of waterproofing the crimping part by designing the crimping part as the waterproofing structure, there has been proposed the art in which the crimping part is tight-sealed with a resin mold (see, Patent Document 1) or the art in which a heat contractive tube covered around the crimping part is contracted thereby to tight-seal the crimping part (see, Patent Document 2).    [Patent Document 1] Japanese Patent Publication Number 2001-167821 A    [Patent Document 2] Japanese Patent Publication Number 2005-268194 A
However, in case of the waterproofing methods which are disclosed in the above described Patent Documents, an outer shape of the crimping part is swelled outward by 0.1 mm or more from the outer shape of the crimp terminal, in both cases. Consequently, it becomes unable to fit the crimp terminal by engagement to the connector housing of which a clearance with respect to the crimp terminal is set to be 0.1 mm or less.
In short, in case of the crimp terminal formed of copper family material to be fitted by engagement to the connector housing, it is impossible to apply the conventional waterproofing structure to the crimping part. Moreover, because waterproofing performance of the crimping part cannot be secured, there has been such a problem that it is impossible to enhance erosion resistance of the crimping part.


A system (10) for manufacturing a photocathode includes a support (12) and a polishing pad (14) disposed adjacent the support (12). The polishing pad (14) is operable to polish the photocathode in response to movable contact of the photocathode relative to the polishing pad (14). The system (10) also includes a rinsing system (16) coupled to the support (12). The rinsing system (16) is operable to deliver a rinsing agent to the polishing pad (14). The system (10) further includes a control system (62) operable to automatically regulate delivery of the rinsing agent to the rinsing system (16) at a predetermined time period.

This invention relates in general to the field of electro-optics and, more particularly, to a method and system for manufacturing a photocathode.
There are numerous methods and systems for detecting radiation. In one type of detector, photocathodes are used in conjunction with microchannel plates (MCPs) to detect low levels of electromagnetic radiation. Photocathodes emit electrons in response to exposure to photons. The electrons may then be accelerated by electrostatic fields toward a microchannel plate. A microchannel plate is typically manufactured from lead glass and has a multitude of channels, each one operable to produce cascades of secondary electrons in response to incident electrons. A receiving device then receives the secondary electrons and sends out a signal responsive to the electrons. Since the number of electrons emitted from the microchannel plate is much larger than the number of incident electrons, the signal produced by the device is stronger than it would have been without the microchannel plate.
One example of the use of a photocathode with a microchannel plate is an image intensifier tube. The image intensifier tube is used in night vision devices to amplify low light levels so that the user can see even in very dark conditions. In the image intensifier tube, a photocathode produces electrons in response to photons from an image. The electrons are then accelerated to the microchannel plate, which produces secondary emission electrons in response. The secondary emission electrons are received at a phosphor screen or, alternatively, a charge coupled device (CCD), thus producing a representation of the original image.
Another example of a device that uses a photocathode with a microchannel plate is a scintillation counter used to detect particles. High-energy particles pass through a scintillating material, thereby generating photons. Depending on the type of material used and the energy of the particles, these photons can be small in number. A photocathode in conjunction with a microchannel plate can be used to amplify the photon signal in similar fashion to an image intensifier tube. The detector can thus be used to detect faint particle signals and to transmit a signal to a device, e.g., a counter, that records the particle""s presence.
A photocathode may include one or more layers of material deposited or grown on a surface or substrate of the photocathode to provide anti-reflection properties, filtering properties, electron transportability properties, and other suitable properties associated with the photocathode. After the layers have been deposited or grown on the surface of the photocathode, the surface of the photocathode generally requires polishing to reduce the layer to a predetermined thickness to provide the desired photocathode properties. The polishing process generally includes translating the photocathode across a polishing pad and/or polishing compound for a predetermined amount of time. Thus, the amount of material removal from the photocathode is a function of the abrasive characteristics of the polishing pad and/or chemical etching properties of the polishing compound, the amount of pressure applied to the photocathode during polishing, and the amount of time the photocathode is polished.
Various types of processes may be used to polish the photocathode. An example polishing process may include applying a polishing compound to a polishing pad and translating the photocathode across the polishing pad and polishing compound for a predetermined period of time. After the predetermined time period has elapsed, the photocathode may be removed from the polishing compound and transported to a rinsing station where excess polishing compound may be removed from the photocathode.
However, prior systems and methods for manufacturing a photocathode suffer several disadvantages. For example, chemical properties of the polishing compound may cause oxidation of the photocathode as the photocathode is removed from the polishing pad. As a result of the oxidation, the photocathode may require additional processing to remove the oxidation or the photocathode may be unsuitable for various applications.
Accordingly, a need has arisen for a better technique having greater flexibility and adaptability for manufacturing a photocathode. In accordance with the present invention, a system and method for manufacturing a photocathode is provided that substantially eliminates or reduces disadvantages and problems associated with previously developed systems and methods.
According to one embodiment of the present invention, a system for manufacturing a photocathode comprises a support and a polishing pad disposed adjacent the support. The polishing pad is operable to polish the photocathode in response to movable contact of the photocathode relative to the polishing pad. The system also comprises a rinsing system coupled to the support. The rinsing system is operable to deliver a rinsing agent to the polishing pad. The system further includes a controller. The controller is operable to deliver the rinsing agent to the rinsing system at a predetermined time period.
According to another embodiment of the present invention, a method for manufacturing a photocathode comprises positioning a polishing pad on a support and disposing a rinsing system adjacent the polishing pad.
The method also comprises polishing the photocathode with the polishing pad by movable contact of the photocathode relative to the polishing pad. The method also comprises transferring a rinsing agent to the polishing pad via the rinsing system at a predetermined time period. The method further comprises rinsing the photocathode with the rinsing agent prior to removing the photocathode from contact with the polishing pad.
The technical advantages of the present invention include providing a system and method for manufacturing a photocathode that provides greater uniformity and consistency of photocathodes. For example, according to one aspect of the present invention, a rinsing system automatically delivers a rinsing agent to the photocathode after the photocathode has been polished for a predetermined time period. The rinsing agent is delivered to the photocathode such that the photocathode may be rinsed prior to removal of the photocathode from the polishing pad. Thus, chemicals that may cause oxidation of the photocathode are substantially removed from the photocathode prior to removing the photocathode from the polishing pad.

Method and system for manufacturing a photocathode


The embodiments of the present invention disclose a method, device, and system for video communication, and relate to the field of video conference technologies, so as to implement automatic switching of video images during a video conference. The method includes: obtaining video image signals and voice information of a first site; determining video image signals including a video object according to the video image signals and voice information of the first site; and sending the video image signals including the video object to a second site. The method, device, and system provided in the embodiments of the present invention implement automatic switching of video image signals during the video conference, thus avoiding switching errors caused by human factors and improving the efficiency of the conference.

A video conference system enables people in different places to perform remote communication and collaboration face to face. A participant of a site can see participants of other sites through a display screen, and hear the voice of the current speaker at other sites through an audio device, which enables the participant to feel as if all participants are present at a same physical site. At present, many video conference systems display the participants in real size to improve the efficiency and effect of communication between participants at different sites; in this way, the display screen at a site can hardly display all participants at other sites simultaneously.
For example, three participants A1, A2, and A3 are at site A, while display screens of other sites can display only two of them, such as A1 and A2; when A3 needs to speak, it is necessary to enable participants of other sites to see the image of A3 through display screens; in this case, video switching is required.
In the prior art, video switching is implemented during a video conference in the following ways:
(1) A switching button is installed in front of each participant at the site. When a participant needs to speak and participants of other sites need to see the speaker, the speaker can press the switching button, notifying the system to perform video switching, so that the participants of other sites can see the video of the speaker through display screens.
(2) A conference administrator is arranged at each site to perform manual video switching. When it is necessary to switch to the video of the current speaker, the conference administrator judges which participant is speaking through senses such as sight and hearing, and then performs video switching manually, so that participants of other sites can see the video of the current speaker through display screens.
In the process of implementing the video switching during the video conference, the inventor finds at least the following problem in the prior art:
No matter whether the speaker or the conference administrator performs video switching, the switching is a manual process, which tends to interrupt the progress of the conference or cause problems such as video switching errors, thus affecting the efficiency of the conference.

Method, device, and system for video communication


An image processing apparatus is provided with an input of multivalued image data, converts the inputted multivalued image data into binary image data, generates color data based upon the binary image data resulting from the conversion, judges identity between the generated color data and color data of a plurality of different specific images, and outputs the binary image data resulting from the conversion if non-identity is judged. If identity is judged to exist, however, output of the binary image data resulting from the conversion is halted.

1. Field of the Invention
This invention relates to an image processing apparatus, such as an image processing apparatus having a function for detecting a specific image, such as that of a bank note or security.
2. Description of the Prior Art
Apparatus of this type that have recently been developed feature a large number of tones and a high-image quality in which an image signal expressing one pixel is composed of a large number of bits. Owing to greater sophistication of image processing and an improvement in recording density, even a binary printer is capable of providing a high picture quality approaching that of a multivalued printer.
However, the recent improvements in the picture quality of copying machines which now have a color capability have been accompanied by the fear of counterfeiting, in which specific originals such as bank notes and securities, which are not meant to be copied, are duplicated at such a high picture quality that the copies are almost indistinguishable from the originals.
Thus, a serious shortcoming in the prior art mentioned above is that effective measures for preventing counterfeiting have not been developed for binary printers in which one pixel is expressed by one bit (in the case of color, by the three bits, namely R, G, B bits, or by four bits, namely C, M, Y and Bk bits).


Acoustic ringing and adverse effects from variations in the NQR detection of explosives and narcotics are minimized or eliminated. A specimen is irradiated with a modified steady state steady state free precession (SSFP) pulse sequence which combines a phase-alternated pulse sequence (PAPS) with a non-phase-alternated pulse sequence (NPAPS). The resulting signals from the PAPS and NPAS may then be coadded to cancel out the FID contributions to the signals. By canceling out the FID contributions to the signals, the effects of probe ringing and other extraneous responses, as well as the effect of temperature variation, are minimized or removed. The present method is especially effective in the detection of explosives and narcotics having .sup.14 N or .sup.35,37 Cl nuclei. A steady state free precession pulse which is especially useful with the method of the present invention is the strong off-resonance comb (SORC). In another embodiment of the invention, the effects of probe ringing can also be minimized or removed by repeating the detection procedure at a frequency which is sufficiently off-resonance so that only frequency independent effects, such as probe-ringing, can be observed.

1. Field of the Invention
The present invention relates generally to nuclear quadrupole resonance (NQR) and more specifically to the detection of explosives and narcotics by nuclear quadrupole resonance.
2. Description of the Background Art
As described in U.S. Ser. No. 07/704,744, filed May 23, 1991, now U.S. Pat. No. 5,206,592 and in U.S. Ser. No. 07/730,772, filed Jul. 16, 1991, now U.S. Pat. No. 5,238,234 both of which are incorporated herein by reference, NQR can be an effective means of detecting explosives and narcotics. In particular, NQR is useful in the detection of nitrogenous or chlorine-containing explosives and narcotics (or, more generally, materials containing quadrupolar nuclei such as .sup.14 N, .sup.35,37 Cl, etc), such as carried in luggage, mail, small cargo or on a person. This general NQR approach is referred to as `pure` NQR to indicate that no externally applied static magnetic field is required.
Unfortunately, the radiofrequency (RF) pulses used in the typical NQR explosives and narcotics detection sequences will induce an acoustic ringing in certain items, typically magnetized iron or ceramic, which may occasionally be found in baggage. This ringing may last on the order of a millisecond and be comparable in size to the NQR signal amplitude corresponding to a threat quantity of explosives.
If this acoustic ringing were not removed, then one could suffer an increased false alarm rate (false positive) for those bags containing such materials. Alternatively, a low false alarm rate could be achieved by increasing substantially the threshold `alarm` setting, but at the expense of increasing the minimum detectable quantity.
Acoustic ringing (sometimes called magnetoacoustic ringing or probe ringing) is a well-known, though not completely well-understood, phenomenon in conventional NMR, where an external, static magnetic field is used. The basic mechanism is that the RF pulse induces eddy currents in a conductor. In a magnetic field, a force acts on these currents and hence on the conductor, inducing acoustical energy that bounces back and forth within the conductor. This pulse of acoustic energy correspondingly alters the magnetic coupling to the receiver coil, inducing a `signal` that is in phase with the driving RF pulse and that persists until the acoustic energy is dissipated in the system.
Since there is no static magnetic field in pure NQR, the acoustic ringing mechanism is different than for NMR applications. A likely explanation is that the ferromagnetic domains in magnetized materials try to realign in response to the applied RF magnetic field. These (partial) realignments cause lattice distortions generating acoustic energy that then reflects back and forth within the sample.
For concreteness the present invention disclosure considers the elimination of acoustic ringing, though it will be appreciated that other mechanisms that contribute to extraneous probe ringing are also amenable to elimination according to the approach described herein.
In the related art of nuclear magnetic resonance (NMR), there are a number of approaches to reducing or removing extraneous probe ringing. Since the ringing is generally in the probe body or RF coil, rather than the specimen under study, mechanically redesigning the probe to employ materials that rapidly damp the acoustic wave is a viable option in NMR.
There are also a number of NMR pulse sequences that have proven effective in largely eliminating the effects of acoustic ringing. Such sequences generally rely upon the ability to invert the sign of the NMR signal in the rotating reference frame, but not that of the acoustic ringing signal in the same frame (or vice-versa). Thus, provided the offending acoustic ringing signal is reproducible over time, one can arrange to alternatively add and subtract the incoming signal so that the desired NMR signal is consistently added (in effect), while the acoustic signal alternately adds and subtracts to zero. As will be shown below, the cancellation techniques conventionally used for NMR are not directly applicable to NQR.
To remove the acoustic ringing in NMR, a second, well-known approach is to rely on the ability to invert (change the sign of) NMR magnetization by a conventional 180.degree. or .pi. pulse. One possible sequence consists of a .pi./2 excitation pulse that produces, say, a positive NMR signal and a positive acoustic ringing signature. After magnetization is regenerated in a time T.sub.1, the spin-lattice relaxation time, a .pi. inverting pulse is applied, followed a time t.sub.d later by a .pi./2 pulse. All pulses have the same phase. Provided t.sub.d is much less than T.sub.1, the NMR signal will be inverted. Also, provided t.sub.d is long compared to the acoustic ringing signal, the acoustic signal will be the same as it was after the initial .pi./2 pulse. Addition and subtraction of the resulting signals removes the component of acoustic ringing, while preserving the NMR signal.
However, for the general NQR case, these simple strategies presented above are not appropriate. In the detection of explosives or narcotics in a package or on a person by NQR, the acoustic ringing arises from magnetized components within the specimen, e.g. a suitcase or package. Identifying and then removing the offending contents is not a desirable solution. Furthermore, the straightforward sequence discussed above for NMR does not work for NQR. For a polycrystalline specimen, it is well-known that there is no RF pulse that inverts the entire NQR `magnetization`.
Additionally, it is well-known that the exact NQR resonance frequency varies with temperature. Obviously, this temperature variation has some undesirable effects in NQR detection schemes. While conventional schemes to minimize these undesirable effects exist, the method of the present invention can effectively remove both probe ringing and minimize temperature effects.

Removing the effects of acoustic ringing and reducing temperature effects in the detection of explosives by NQR

The United States of America as represented by the Secretary of the Navy


Access to an access point is restricted to a plurality of client devices having wireless connections with the access point. The wireless connections conform to a wireless networking protocol. A first data transmission rate is the lowest data transmission rate defined by the wireless networking protocol. It is determined that a second data transmission rate is used between a first client device of the plurality of client devices and the access point. The second data transmission rate is the lowest data transmission rate used by the plurality of client devices. The second data transmission rate is greater than the first data transmission rate. Responsive to said determining that the second data transmission rate is the lowest data transmission rate used by the plurality of client devices, a beacon frame data transmission rate is set to the second data transmission rate.

Embodiments of the inventive subject matter generally relate to the field of networking, and, more particularly, to wireless access points.
Access points (hereinafter "APs") used to be specialized network devices that connect wireless devices (hereinafter "client devices") to a wired network. As technologies improve, AP functionality may be integrated into other devices. For example, a computer can act as an AP, sharing a wired or wireless network with a smart phone. Smart phones, similarly, can share Internet connectivity over a cellular network with a wireless-enabled computer, such as a laptop. APs are frequently referred to as "hotspots," and hotspots created using mobile devices may be referred to as "mobile hotspots."
As AP functionality migrated to less specialized and mobile devices, the general functionality was not changed to take into account potential problems. For example, devices designed specifically to function as APs are generally connected to a "permanent" power source, such as a local power grid (via a wall outlet, for example). Mobile devices, however, do not always have a permanent power source. For devices that rely, at least part of the time, on battery power, inclusion of AP functionality can increase power consumption, thereby undesirably decreasing battery life.

Beacon frame data transmission rate adjustment


A power-recapture method and system converts mechanical energy, which would otherwise be dissipated, into available electrical energy. A plurality of computer-coordinated Electric Generators are arranged with salient sensors that detect appropriate motion then adjust the phasing and intensity of electromagnets of the Electric Generator to optimally convert variable mechanical motion into electric current.

Energy conservation and climate change mitigation have fostered the development of alternatives to the direct use of fossil fuels. Light to electrical energy conversion in the form of solar panels is one alternative but this has limitation due to:                a. The large area required for efficient generation in urban areas so that the real estate available is mainly confined to residential or building roofs.        b. The remote geographical locations of the regions with the optimal days per year of sunlight so that the power transfer losses for connecting to the National Power Grid become significant.
Electrical energy generated by conventional wind turbines has similar limitations. In contrast the present invention takes advantage of existing real estate to provide dual use; moreover, the power is generated close to potential usage sites and users. One valuable source of energy is that generated by the movement of vehicular traffic. For combustion engine vehicles the engine reaches sufficient temperatures that the heat must be dissipated usually with a coolant system although for smaller engines air cooling will suffice. For a conventional automobile powered by internal combustion, the energy efficiency is about 20% with the remaining 80% dissipated as heat. Some of the kinetic energy can be harvested and some of the frictional heat avoided with the present invention.
Vehicular traffic generates and then dissipates energy in at least four forms.                1. The weight of the vehicle exerts pressure on the surface over which it passes. In the United States the average car, SUV or light truck, according to the US Department of Transportation, weighs approximately 4000 lbs (1814 kg). Assuming uniform distribution of weight, each wheel of a four-wheeled vehicle supports 1000 lbs (454 kg). With a contact surface of 32 square inches (206 square centimeters) the pressure would be 21.5 newtons per square centimeter. A portion of this pressure differential is harvested with the Piezoelectric Sensors of the present invention.        2. The translational kinetic energy of a moving object, E sub t, is ½ mv2. So the energy possessed by a 4000-lb (1814-kg) vehicle traveling at 60 mph (27 m/s) is ½ (1814) (27)2 or 1.32 million joules which in electrical terms is equivalent to 367 Kilowatt-hours. There are 250 million such vehicles in the United States so if all were in motion at highway speeds they would constitute 91.8 billion Kilowatt-hours which is the electrical energy sufficient for 8.3 million homes for an entire year. In heavy traffic around any major city or on the major highways several hundred vehicles may pass by a single point in a given hour so the energy harvesting potential is significant. But that energy is dissipated usually in the form of heat when the vehicles brake (see below). If some portion of that energy could be recaptured rather than dissipated, the savings would be considerable. The linear or rotational displacement of the vehicle over the surface on which it travels exerts an equal and opposite force between the vehicle's wheels and the surface. A portion of this force differential is harvested by the Electric Generator of the present invention.        3. A vehicle's motion displaces its surrounding fluid even when drag is minimized through efficient aerodynamic design. According to the US Energy Information Administration on average 5.3% of the energy required to move a vehicle is needed to push the air off the path of the vehicle. The motion of the displaced fluid outside the laminar flow zone around a vehicle presents a source of energy to be harvested by the present invention as described in the second preferred embodiment.        4. As a vehicle slows or brakes to a stop the kinetic energy is typically dissipated as heat. However, such kinetic energy can be harvested by the present invention as described in the preferred embodiments.
The present invention is a power-recapture method and system for converting mechanical energy that would otherwise be dissipated into available electrical energy. Said invention teaches an innovative and comprehensive approach to energy harvesting from vehicular and ambient motion and has advantages over prior art by deploying the system in close proximity to energy-consuming users and devices.


A removable clip that engages an inflator. The clip prevents inadvertent piercing of a gas cartridge secured to the inflator and indicates whether or not the inflator has been used. The clip is carried on the lanyard that is pulled to activate the inflator and includes a pair of laterally extending arms having detents formed on their respective free ends that engage opposite ends of a bore formed in the inflator. The detents retain the clip in place until the lanyard is pulled, and the clip remains on the lanyard after the lanyard has been pulled so that the clip is not lost.

Inflators are typically provided with a "D"-shaped keyway formed therein to slidably receive a complementally formed inflation manifold that projects perpendicularly from the exterior surface of an inflatable article. Typically, the distal free end of the manifold is externally threaded and a nut engages said free end to secure the manifold to the inflator.
A gas cartridge is typically screw threadedly engaged with an inflator in such a way that visual inspection of the inflator and cartridge secured thereto does not reveal whether or not the cartridge has been used. More particularly, the puncturable end of the cartridge cannot be visually inspected without unscrewing the cartridge from the inflator. When an inflatable article such as a life vest or raft is needed quickly, ample time may not be available to perform an inspection of the cartridge, especially if one must select a vest or raft from a stack of the same, some of which may contain spent cartridges.
Inadvertent puncturing of the gas cartridge can also occur, because inflators are intentionally designed for ease of puncturing. Thus, a light tug on a lanyard causes a bell crank to pivot about a pivot shaft and to thereby drive a piercing pin into the cartridge. Accordingly, there is a need to provide a protective cover for a typical inflator that guards against inadvertent release of gas from a cartridge secured thereto. Perhaps even more importantly, there is a need for an indicator that will visually indicate whether or not a lanyard has been pulled.
The art has developed a clip that releasably engages the inflator and which overlies the bell crank to thereby provide some resistance to unintentional rotation of the bell crank. The clip adequately performs its intended function, but once the clip has been disengaged from the inflator by a strong pull on the lanyard, the clip is simply ejected and lost. Thus, there is a need for a clip that is not lost after use and which will indicate whether or not a lanyard has been pulled.

Protective cover and pulled lanyard indicator for an inflator


A wireless communication base station device, terminal device, and method have reduced signaling while maintaining high scheduling gain. A judgment unit pre-stores a correspondence between the number of code words and the number of clusters to reduce the maximum value for the number of clusters allocated to each terminal as the number of code words increases, and thus determines the maximum value for the number of clusters based on the number of code words acquired. Based on the number of code words for a transmission signal from a terminal, an estimated value for the reception quality, and the maximum value for the number of clusters that is output by the judgment unit, a scheduling unit schedules the allocation of the transmission signal transmitted by each terminal to a transmission band frequency (frequency resource) so as not to exceed the maximum value for the number of clusters.

In uplink of 3rd generation partnership project long term evolution (3GPP LTE), consecutive bands are allocated to individual terminals. In each band, data signals and pilot signals are time-multiplexed and transmitted.
Notification information for each terminal includes transmission band information and control information. Here, the transmission band information includes start and end resource block (RB) numbers of an allocation band (a minimum bandwidth is set to 1 RB) determined from a system bandwidth NRB. The number of notification bits of the start and end RB numbers is expressed by following equation 1.
                    (                  Equation                                                              1                )                                                                                ⌈                                          log                2                                                          (                                  C                  2                                                                                N                        RB                                            +                      1                                                                        )                                      ⌉                    =                      ⌈                                          log                2                            (                                                                    (                                                                  N                        RB                                            +                      1                                        )                                                                          (                                          N                      RB                                        )                                                                    2                  !                                            )                        ⌉                                              [        1        ]
Further, the control information includes 5-bit modulation and coding scheme (MCS) information, 2-bit TCP command information, 1-bit new data indicator (NDI) information, 3-bit cyclic shift information, and the like. That is, in this example, the number of bits to be required for notification of control information is 11.
In Non-Patent Literature 1, in addition to consecutive band allocation in uplink of LTE-Advanced which is a developed version of 3GPP LTE, allocating non-consecutive bands (non-consecutive allocation) is discussed (see FIG. 1). Flexible frequency scheduling is possible thanks to allocating non-consecutive bands. Further, in the non-consecutive allocation, allocated consecutive bands are called a cluster.
Meanwhile, in Non-Patent Literature 2, multiple input multiple output (MIMO) transmission of data signals is discussed. In the MIMO transmission in LTE, transmission control (MCS control and the like) can be performed in units of codeword, and flexible space scheduling is possible. Further, a codeword represents a block, which is a retransmission unit of hybrid automatic repeat and request (HARQ).
When the non-consecutive allocation and the MIMO transmission are applied, a schedule gain based on space scheduling or frequency scheduling may increase.

This patent is subject to a terminal disclaimer.

Communication apparatus and communication method

PANASONIC INTELLECTUAL PROPERTY CORPORATION OF AMERICA


A device for providing gated data signals includes a delay path configured to receive an input signal and output the input signal that is delayed from the input signal by a time interval; a gating signal generator configured to supply a gating signal; a gating circuit configured to receive the data signal from the delay path at the data input, receive the gating signal at the gating input, and output at the data output an output signal indicative of the received data signal when the gating signal is present at the gating input; and a delay controller configured to receive a variable delay control signal and set the delay time interval according to the delay control signal.

This disclosure relates generally to timed input and output operations and circuits in electronics circuits. This disclosure more specifically relates to memory read and write method and apparatus with improved performance and reliability.
Certain timed input and output operations, such as input (READ) and output (WRITE) operations for memory devices, involve supplying an input or output signal and gating the signal. The relative timing between the input or output signal and the gating signal can significantly, or even critically, affect the performance of the devices. Efforts continue in improving reliability and performance of timed input and output operations in memory devices.

TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY, LTD.


Differentially connected capacitive sensors are mechanically coupled with the flexible capacitor plate of one sensor coupled to the source of pressure to be measured, the flexible capacitor plate of the other sensor coupled to ambient pressure. In a second embodiment, inaccuracies due to forces on the flexible plate are minimized by providing a housing with a tapered inner wall, an O-ring and a support to apply a radial load to the sensor due to clamping action from the tapered housing against the O-ring to provide a seal for the pressure sensing chamber. In a further embodiment, the cost of fabrication of the pressure transducer is minimized by providing the housing as a one piece cup. The electronics are mounted on the exterior surface of the low pressure side of the ceramic capacitor pressure sensing element and sealed in thereat by potting with an epoxy. In addition, an electrical pin connector from the electronics and a vent to the low pressure surface of the movable plate are secured in the potting material and extend externally thereof. In a further embodiment, pressures applied to the movable diaphragm of the pressure sensing element by the gasket are eliminated by providing a ceramic capacitor having a movable diaphragm element having smaller length and width dimensions than the fixed capacitor substrate. The gasket is positioned around the movable diaphragm element and on the fixed capacitor plate with the housing being stepped to apply a force against the gasket but remain out of contact with the movable diaphragm element.

1. FIELD OF THE INVENTION
This invention relates to pressure sensors having therein transducers for operation in low pressure (i.e., about 1 to 5 inches of water) environments and, more specifically, to such pressure sensors having capacitive pressure transducers.
2. BRIEF DESCRIPTION OF THE PRIOR ART
Pressure sensing devices using capacitive pressure transducers are well known and have received substantial acceptance. An example of such prior art pressure sensing devices is set forth in the patent of Charboneau et al. (U. S. Pat. No. 4,716,492).
While such prior art pressure sensing devices using capacitive pressure transducers provide good results and at reasonable cost, it is always desirable to improve the accuracy of such devices as well as to diminish the cost of fabrication.
In such prior art transducers using a single fixed substrate and a flexible diaphragm, there is no allowance for a true gauge pressure measurement. Furthermore, inaccuracies in result are provided due to the sealing of about 6 psia between the diaphragm and the substrate. While it is readily apparent that a true gauge pressure can be provided by opening the space between the diaphragm and the substrate to atmospheric pressure, this approach has also caused problems. As pressure greater than atmospheric pressure is applied to the flexible diaphragm, the diaphragm moves toward the fixed substrate. Since two silver plates are deposited, one on the substrate and one on the diaphragm, a pressure variable capacitor is created. The major disadvantage to this approach is therefore that atmospheric contaminants, such as chlorine and hydrogen sulfide, will damage the silver plates, thereby ultimately rendering the device non-functional.
A further problem encountered in pressure sensors of the above described type is that extraneous axial pressures applied to either or both of the plates of the capacitive transducer can cause inaccuracies in the actual pressure measurement. Such extraneous pressures often result from pressures applied to one or both of the capacitive transducer elements by the housing for the sensor itself.
A yet further problem encountered in pressure transducers of the above described type is that it is desirable to minimize the cost of fabrication. A cause of higher fabrication cost is the use of a separate printed board for the electronics required to provide an appropriate electrical indication of the sensed pressure.
A still further problem encountered in the pressure transducers of the above described type is that forces from the packaging or housing are applied to the movable diaphragm through the gasket, thereby providing an extraneous axial pressure to the movable diaphragm which results in inaccuracies in measurement.