Patent Document

FIELD OF THE INVENTION 
   In general, this invention relates to handling fluid materials including primarily gases, but not excluding the handling of other flowable materials. More specifically, this invention relates to an apparatus for controlling fluid flow, such as a pressure protection valve or check valve suitable for use in a pressurized-fluid system. 
   SUMMARY OF THE INVENTION 
   According to the present invention, a valve is provided which comprises a housing having an inlet and an outlet fluidly connected by a fluid flow path. A valve element is provided that is movable between a first position and a second position. When the valve element is in the first position, it blocks fluid communication along the fluid flow path. The valve also includes a resilient member fluidly sealed from the fluid flow path. The resilient member urges the valve element from its second position to its first position such that the resilient member moves to its first position when the pressure of fluid entering the inlet is below a threshold amount. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention is illustrated by way of example and is not limited by the figures of the accompanying drawings, in which like reference numbers indicate similar parts: 
       FIG. 1  shows a partially-sectioned perspective view of an inline pressure protection valve made according to the principles of the present invention illustrating an annular piston thereof in a first position for blocking fluid flow; 
       FIG. 2  shows a partially-sectioned perspective view of the inline pressure protection valve of  FIG. 1  illustrating the annular piston thereof in a second position for allowing fluid flow; 
       FIG. 3  shows a perspective view of an alternative component of the inline pressure protection valve according to the principles of the present invention; and 
       FIG. 4  shows a block diagram of a compressed air system incorporating the inline pressure valve according to the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to the drawings and  FIG. 1  in particular, a valve  100  of the present invention is shown in a partially-sectioned perspective view. The valve  100  is a pressure protection valve configured to be placed inline with a compressed-fluid system. The valve  100  includes an inlet  110  for receiving pressurized fluid into an antechamber  115  and an outlet  120  for exhausting the pressurized fluid from an outflow path  125 . The combination of the antechamber  115  and the outflow path  125  constitutes a fluid flow path from the inlet  110  to the outlet  120 . The size and shape of the inlet  110  and outlet  120  can vary depending on application to allow for connection inline with a pressurized fluid system. 
   The valve  100  has a housing  130 , which extends in a longitudinal direction between the inlet  110  and the outlet  120 . The valve  100  includes an annular piston  140 , which serves as a valve element between the antechamber  115  and the outflow path  125 , for moving in the longitudinal direction within the housing  130  to open and close the valve  100 . A spring  150  serves as a resilient member for biasing the annular piston  140  towards a first position, which is a closed-valve position as shown in  FIG. 1 . The spring  150  is located in a spring-guide chamber  160 , and is held in place by being fixed at one end (i.e., upper end as oriented in  FIG. 1 ) to the housing  130  and fixed at an opposite end (i.e., lower end as oriented in  FIG. 1 ) to the annular piston  140 . When fluid pressure at the inlet  110  increases beyond a certain predetermined threshold level, it overcomes the bias of the spring  150  causing the annular piston  140  to move towards a second position, which is an open-valve position as shown in  FIG. 2 . 
   Note that the valve  100  includes a grooved plate  170 , which serves as an apertured member, and a blocking plate  180 , which serves as a blocking member. When the annular piston  140  is in the closed-valve position, the blocking plate  180  and the annular piston  140  block fluid flow between the antechamber  115  and the outflow path  125 , thereby preventing fluid from flowing from the inlet  110  to the outlet  120 . On the other hand, when the annular piston  140  is in the open-valve position, radial grooves in the grooved plate  170  provide for fluid communication between the antechamber  115  and the outflow path  125 , thereby allowing fluid-flow from the inlet  110  to the outlet  120 . 
   It is contemplated that the grooved plate  170  can be provided in alternate forms, as long as a fluid path is provided between the antechamber  115  and the outflow path  125 . For example, the grooved plate  170  can be replaced with a drilled plate  170 ′, which is shown in  FIG. 3 . The drilled plate  170 ′ is an example of an alternate form of an apertured member of the present invention. The drilled plate  170 ′ has a central aperture  220  that is in fluid communication with the outflow path  125 . The drilled plate  170 ′ also includes one or more radial apertures  230 , each in fluid communication with the central aperture  220  and the antechamber  115 . When the annular piston  140  is in the open-valve position, the radial apertures  230  in combination with the central aperture  220  provide for fluid communication between the antechamber  115  and the outflow path  125 , thereby allowing for fluid communication between the inlet  110  and the outlet  120 . On the other hand, when the annular piston  140  is in the closed-valve position, the annular piston  140  blocks the radial apertures  230 , thereby preventing fluid-flow between the antechamber  115  and the outflow path  125 . 
   In addition, it is further contemplated that if the central aperture  220  is formed such that it does not extend all the way through the drilled plate  170 ′, then it is possible to use the drilled plate  170 ′ in place of the combination of the grooved plate  170  and the blocking plate  180 . 
   Referring again to  FIGS. 1 and 2 , an inner bore  190 , which is a portion of the outflow path  125 , is defined by an inner side of a partition  200 . The spring-guide chamber  160  is a space formed between an outer side of the partition  200  and an inner side of the housing  130 . The spring-guide chamber  160  is bound at one end (upper end as oriented in  FIGS. 1 and 2 ) by a bridge portion  205 , which extends between the housing  130  and the partition  200 . The spring-guide chamber  160  is bound at another end (lower end as oriented in  FIGS. 1 and 2 ) by the annular piston  140 . The annular piston  140  is fitted between the inner side of the housing  130  and the outer side of the partition  200 . It is desirable to fluidly seal the spring-guide chamber  160  from fluid in the fluid flow path between the inlet  110  and the outlet  120 . It is contemplated that there are numerous ways of ensuring an adequate seal. In the present embodiment, inner and outer o-ring seals  142  and  144  are used. As shown in  FIGS. 1 and 2 , the inner o-ring seal  142  is provided between an inner side of the annular piston  140  and the outer side of the partition  200 , and the outer o-ring seal  144  is provided between an outer side of the annular piston  140  and the inner side of the housing  130 . The seals  142  and  144  combined with the annular piston  140  fluidly seal the spring-guide chamber  160  from the fluid flow path between the inlet  110  and the outlet  120 , including the antechamber  115  and the outflow path  125 . 
   While the spring-guide chamber  160  is fluidly isolated from the fluid flow path within the valve  100 , it is desirable to allow fluid to enter and escape from the spring-guide chamber  160  as the size of the spring-guide chamber  160  changes with the movement of the annular piston  140 . For example, when the valve  100  opens, the annular piston  140  compresses the spring  150  causing a reduction in the amount of space within the spring-guide chamber  160  (note the spring-guide chamber  160  shown in  FIG. 2  is smaller than the spring-guide chamber  160  shown in  FIG. 1 ). Therefore, if there is no way for a fluid in the spring-guide chamber  160  to escape while the spring  150  is compressing, then the fluid in the spring-guide chamber  160  would also need to be compressed to allow for movement of the annular piston  140 . Similarly, if there is no way for fluid to enter the spring-guide chamber  160 , the fluid in the spring-guide chamber  160  would have to expand as the spring  150  is decompressing. So, in order to avoid this situation, a vent  210  is provided in the housing  130  for allowing fluid to flow between the spring-guide chamber  160  and the outside of the valve  100 . On the other hand, it is contemplated that the vent  210  could be eliminated if the effect of the fluid trapped in the spring-guide chamber  160  is considered in the design of the valve  100 , for example if the spring  150  is selected with consideration given to the force necessary for compression of the fluid trapped in the spring-guide chamber  160 . 
   The operation of the valve  100  will now be described. When the valve is closed as shown in  FIG. 1  and a fluid is forced into the antechamber  115  through the inlet  110 , pressure is applied to the annular piston  140 . When this pressure exceeds a certain threshold amount, for example 70 psi, the force caused by this pressure on the annular piston  140  begins to overcome the opposing force on the annular piston  140  from the spring  150 . At this point, the annular piston  140  begins to compress the spring  150  and move towards the open-valve position shown in  FIG. 2 . As the fluid pressure in the antechamber  115  continues to increase, the annular piston  140  continues to move towards the open-valve position, gradually uncovering the grooved plate  170 . Once the fluid pressure in the antechamber  115  reaches a second threshold level, for example 120 psi, the force resulting from the fluid pressure is sufficient to move the annular piston  140  all the way to the open-valve position. At the open-valve position, valve  100  is fully open and the fluid conduits, i.e., grooves, in the groove-plate  170  are most completely uncovered by the annular piston  140 . 
   If, while the valve  100  is open, fluid pressure in the antechamber  115  is reduced—for example, below 120 psi staying with the above example—then the force of the spring  150  acting on the annular piston  140  begins to overcome the opposing force caused by the fluid pressure in the antechamber  115 . In this situation, the annular piston  140  begins to gradually move from the open-valve position shown in  FIG. 2  towards the closed-valve position shown in  FIG. 1 . While the annular piston  140  moves towards the closed-valve position, the annular piston  140  gradually covers and blocks the fluid conduits, i.e., grooves, in the grooved plate  170 . At some point, if the fluid pressure in the antechamber  115  is sufficiently reduced—for example, below 70 psi still staying with the above example—then the annular piston  140  is moved under the force of the spring  150  to the closed-valve position and the valve  100  is fully closed. Thus, unless the fluid pressure in the antechamber  115  is sufficient to generate a force on the annular piston  140  such that the force can overcome the opposing force on the annular piston  140  from the spring  150 , the flow of fluid from the inlet  110  to the outlet  120  is blocked and the valve  100  is closed. 
   It is particularly worth noting that the valve  100  according to the present invention is less sensitive than prior valves to downstream pressure, i.e., pressure at the outlet  120  of the valve. This is because the pressure at the outlet  120  and within the outflow path  125  does not act on the annular piston  140 . Instead, as described above, the annular piston  140  moves according to a force applied from pressure within the antechamber  115 , i.e., inlet pressure, and an opposing force from the spring  150 . Since the spring  150  is fluidly sealed from the fluid flow path between the inlet  110  and the outlet  120 , including the outflow path  125 , the pressure within the outflow path  125  does not contribute to the opposing force from the spring  150  on the annular piston  140 . Thus, it will be appreciated that the valve  100  operates to open and close according to variations in the inlet pressure rather than changes in the differential pressure between the outlet  120  and the inlet  110 . 
     FIG. 4  shows a schematic block diagram of a compressed air system incorporating the valve  100 . The compressed air system includes a compressor  250  for compressing air into a reservoir  260 . The compressor  250  can be controlled by a governor (not shown) for monitoring the pressure of the air stored in the reservoir  260 . The reservoir  260  serves as a source of compressed air for a primary load  270  and an auxiliary load  280 . 
   As an example, the compressed air system shown in  FIG. 4  can be embodied as a vehicle compressed air system where the primary load  270  is an air brake that uses the compressed air from the reservoir  260  for slowing and stopping the rotation of the wheels of the vehicle, while the auxiliary load  280  is an air-ride seat where air is supplied to a driver&#39;s seat for height adjustment. In such a system, it is desirable to isolate the loads so that a leak in the auxiliary load  280  does not affect the function of the primary load  270 . Otherwise, an air leak in the auxiliary load  280  could result in an over-depletion of compressed air from the reservoir  260 , an overworking of the compressor  250  trying to bring the air pressure in the reservoir  260  up to a necessary level, and/or failure of the primary load  270  to function due to inadequate air pressure supplied from the reservoir  260 . 
   The valve  100  is used as a protective measure in the compressed air system shown in  FIG. 4  as follows. The air pressure in the reservoir  260  is reflected in the air pressure within the air supply lines from the reservoir  260  to the loads  270  and  280 . Thus, the air pressure in the reservoir  260  is detected at the valve  100 , disposed inline with the air supply line from the reservoir  260  to the auxiliary load  280 . If the amount of pressure at the inlet  110  of the valve  100  is above a predetermined amount, the pressure of the air overcomes the opposing force of the spring  150  within the valve  100  acting on the valve&#39;s annular piston  140  and the valve  100  is open, allowing the flow of air therethrough to the auxiliary load  280 . On the other hand, if an air leak or over-usage occurs in the auxiliary load  280 , the air pressure within the reservoir  260  and the air supply lines from the reservoir  260  to the loads  270  and  280  will begin to drop as air escapes. As the pressure drops and approaches the predetermined amount, the valve  100  will begin to close as the force of the valve&#39;s spring  150  on the annular piston  140  overcomes the diminishing opposing force of the air pressure. Upon reduction of the air pressure to the predetermined amount, the valve  100  will be closed, effectively stopping any further loss of air from the reservoir  260 . Ideally, the predetermined pressure at which the valve  100  closes will be higher than the minimum amount of pressure necessary for proper function of the primary load  270 . This would allow the primary load  270  to continue normal function despite failure or over-use of the auxiliary load  280 . 
   Although the present invention has been fully described by way of preferred embodiments, one skilled in the art will appreciate that other embodiments and methods are possible without departing from the spirit and scope of the present invention.

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