Bag in box beverage pump

A pump operated with compressed gas is disclosed herein. The pump has two separate cylinders which share a common wall. Pistons are attached to a common shaft that runs through the common wall. The pistons are disposed within each of the cylinders. The pistons divide the cylinders into gas and liquid chambers. The liquid chambers of the cylinder form a liquid system and are in fluid communication with the liquid inlet and outlet. The gas chambers of the cylinders form a gas system and are in communication with gas inlet and outlet. A manifold switching mechanism controls routing of compressed gas to either one of the gas chambers to operate the gas operated pump. The pump may also have an automatic shutoff valve which shuts off operation of the pump when liquid from a liquid source has been depleted.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable

Not Applicable

BACKGROUND

The embodiments disclosed herein relate to a compressed gas operated pump for pumping soda syrup from a syrup bag to a soda dispenser.

Prior art compressed gas operated pumps for pumping soda syrup to a soda dispenser exists. For example, U.S. Pat. No. 5,661,940 ('940 patent) discloses one such pump. Unfortunately, the gas driven pump disclosed in the '940 patent is expensive to manufacture. In particular, the piston has flexible barriers which are over molded over the pistons. This process of over molding the flexible barriers over the pistons is expensive. Moreover, the housing of the gas driven pump of the '940 patent has two separate cylinders and a middle chamber which adds to the cost of the gas driven pump.

Accordingly, there is a need in the art for an improved gas driven pump.

BRIEF SUMMARY

The embodiments of a gas driven pump described herein address the needs discussed above, discussed below and those that are known in the art.

The pump has first and second cylinders which house first and second pistons. These cylinders share a common wall which has an aperture. The aperture receives a shaft. The pistons are mounted to the shaft so that the shaft and pistons reciprocate as a unitary structure along a longitudinal axis of the shaft. Each of the pistons in each of the cylinders define a gas chamber as well as a liquid chamber. Each of the pistons may have a flex barrier which is not attached to the pistons but fits the surface of the pistons. The flex barriers are hermetically secured to the interior surfaces of the cylinders to provide a hermetic seal between cylinders to provide a hermetic seal between the respective gas and liquid chambers. The liquid chambers are in fluid communication with the liquid inlet and liquid outlet. Diaphragm valves are arranged so that as liquid enters one of the liquid chambers, liquid exits out of the other liquid chamber, and vice versa. The gas chambers are in fluid communication with a gas inlet and a gas outlet. A manifold switching mechanism switches gas communication so that as gas enters into one of the gas chambers, gas exits out of the other gas chamber, and vice versa. Compressed gas is introduced into the gas system to drive the pistons. The manifold switching mechanism maintains the gas communication lines until the pistons reach the end or is at nearly the end of the stroke then switches the gas communication lines to reverse the direction of the pistons.

The liquid inlet is connected to a liquid source such as a soda syrup bag. When the liquid source is empty, a vacuum is created which actuates an automatic shut off valve. This automatic shutoff valve cuts off gas supply to the gas system within the pump which stops operation of the pump. The automatic shut off valve may be locked in the off position so that the user can replace the empty liquid source with a new full liquid source. Alternatively, the automatic shutoff valve may be manually actuated and locked in the off position. The shutoff valve may be locked in the off position with a twist and lock mechanism.

More particularly, a pressurized gas operated pump is disclosed which may comprise a first cylinder; a first piston linearly traversable within the first cylinder along a first axis; a first flexible seal hermetically sealed to an interior surface of the first cylinder and the first piston to define a first liquid chamber and a first gas chamber within the first cylinder, the first liquid chamber and the first gas chamber being on opposed sides of the first piston and the first flexible seal; a second cylinder; a second piston linearly traversable within the second cylinder along the first axis; a second flexible seal hermetically sealed to the interior surface of the second cylinder and the second piston to define a second liquid chamber and a second gas chamber, the second liquid chamber and the second gas chamber being on opposed sides of the second piston and the second flexible seal; an elongate shaft linearly traversable along the first axis, the first and second pistons being fixedly attached to the elongate shaft; a manifold for introducing gas into the first gas chamber while venting gas from the second gas chamber, and removing gas from the first gas chamber while introducing gas into the second gas chamber, the manifold being disposed adjacent to the second cylinder and the first cylinder being disposed adjacent to the second cylinder opposite from the manifold; a spool linearly traversable between first and second positions within the manifold along the first axis, the spool aligned in the first position to introduce compressed gas into the first gas chamber and to remove gas from the second gas chamber, the spool aligned to the second position to remove gas from the first gas chamber and to introduce gas into the second gas being attached to the shaft; first and second gas channels routed from the manifold to the first and second gas chambers.

The first and second cylinders may share a common dividing wall. The first piston, second piston and the spool may share a common linear traversal axis.

The pump may further comprise first and second liquid inlet check valves in fluid communication with the first and second liquid chambers. The first and second liquid inlet check valves being may be in a downstream direction.

The pump may further comprise first and second liquid outlet check valves in fluid communication with the first and second liquid chambers. The first and second liquid outlet check valves may be oriented in the downstream direction.

The spool may telescope with respect to the shaft. The pump may further comprise an intermediate member wherein the shaft telescopes with respect to the intermediate member and the intermediate member telescopes with respect to the spool.

The spool may defines one or more cavities which places the first and second gas chambers into fluid communication with an exhaust or a pressurized gas source depending on whether the spool is in first or second positions.

The spool may define a first cavity and a second cavity. The first cavity of the spool may be in fluid communication with the first gas chamber and a pressurized gas source and the second cavity of the spool may be in fluid communication with the second gas chamber and an exhaust when the spool is in the first position.

The first cavity of the spool may be in fluid communication with the first gas chamber and the exhaust and the second cavity may be in fluid communication with the second gas chamber and the pressurized gas source when the spool is in the second position.

In another embodiment, a method of operating a pump is disclosed. The method may comprise the steps of a) linearly traversing a shaft connected to first and second pistons while a spool is disposed at a first position; b) transferring gas from a pressurized gas source to a first gas chamber while the spool is disposed at the first position; c) transferring gas from a second gas chamber to an exhaust while the spool is disposed at the first position; d) transferring liquid from a liquid source to a second liquid chamber while the spool is disposed at the first position; e) transferring liquid from a first liquid chamber to a liquid outlet while the spool is disposed at the first position; f) traversing the spool from the first position to a second position; g) linearly traversing the shaft in an opposite direction while the spool is disposed at the second position; h) transferring gas from a pressurized gas source to the second gas chamber while the spool is disposed at the second position; i) transferring gas from the first gas chamber to the exhaust while the spool is disposed at the second position; j) transferring liquid from the liquid source to the first liquid chamber while the spool is disposed at the second position; k) transferring liquid from the second liquid chamber to the liquid outlet while the spool is disposed at the second position.

In the method, the spool may be stationary at the first position during steps b, c, d, e and the spool may be stationary at the second position during steps h, i, j, k.

DETAILED DESCRIPTION

Referring now to the drawings, a pump10operated with compressed gas (e.g., carbon dioxide) is shown. A liquid source11(e.g., bag filled with liquid, soda syrup bag, etc.) is placed in fluid communication with a liquid inlet12. The pump10flows liquid out of the liquid outlet14under power of the compressed gas. A compressed gas source15is placed in communication with a gas inlet16. The compressed gas source15may be used to power additional pumps10by connecting one or more pumps10to the gas inlet16. The compressed gas powers the pump10to force liquid from the liquid inlet12to the liquid outlet14. After cycling the pump10, the gas is exhausted out of a gas outlet17to the atmosphere through exhaust19. In the event of depletion of the liquid from the liquid source11, an automatic shut off valve18is actuated to stop the flow of compressed gas through the pump10and to stop operation of the pump10. Liquid no longer flows through the pump10. When stopped, the liquid source11can be replaced with a new full liquid source11. It is also contemplated that the auto shut off valve18can be manually shut off by pushing button20. The button20may be held in the off position with a 90 degree helical shut off and lock mechanism.

The pump10described herein has first and second cylinders26,28with a manifold switching mechanism44off to one side of the first and second cylinders26,28. The manifold switching mechanism44shown and described herein is a single spool valve that exhausts gas from first gas chamber and introduces gas into a second gas chamber and reverses the process at the end of the stroke, then exhausts gas from the second gas chamber and introduces gas into the first gas chamber to drive the pump. This configuration as well as other aspects of the pump10reduces the cost to manufacture the pump10over prior art pump designs.

Referring toFIG. 2, the pump10has first and second cylinders26,28which are separated by a common wall29. First and second pistons30,32are disposed within the cylinders26,28, mounted to a common shaft34and reciprocated along a longitudinal axis of the common shaft34within the cylinders26,28. The pistons30,32and the shaft34are linearly traversed as a unitary structure from one side of the cylinder26,28(seeFIG. 2) to the opposite side of the cylinder26,28(seeFIG. 5). This provides for a more robust and reliable system. As the pistons30,32are reciprocated, gas and liquid are introduced and vented from the first gas chamber36, first liquid chamber38, second gas chamber40and second liquid chamber42. To this end, the pump10has a manifold switching mechanism44(seeFIGS. 1 and 2) which introduces gas into the first gas chamber36and vents gas out of the second gas chamber40as the pistons30,32and shaft34are traversed in the direction of arrow45from the position shown inFIG. 5. Near or at the end of the stroke in the direction of arrow45, the manifold switching mechanism44re-routes the gas communication lines so that the compressed gas source15is now in gas communication with the second gas chamber40and the first gas chamber36is in gas communication with the exhaust19. Near or at the end of the stroke in the direction shown by arrow47, the manifold switching mechanism44re-routes the gas communication so that the compressed gas source15is now in gas communication with the first gas chamber36and the second gas chamber40is in gas communication with the exhaust19. The compressed gas powers the pump10cycles through this process and reciprocates the pistons30,32and shaft34until it is manually shut off or until the liquid source11is depleted of liquid.

Near or at the end of the stroke in the direction shown by arrow45shown inFIGS. 2 and 3, a tubular shaped spool46is shifted in the direction of arrow45. The spool46is mounted within a plurality of circular rings48a-d. Rings48a-dare also shown inFIGS. 16-23. O-rings50are mounted to the outer periphery of each of the rings48a-dand the spool46to redirect the flow of gas between the rings48a, b,48b, c,48c, d. When the spool46is in the position shown inFIG. 3, gas is allowed to flow from cavity52between rings48a, bto cavity54as shown by arrow62. The flow of gas travels through mating notches84,85of the rings48a-d(seeFIGS. 21 and 22). Gas continues to flow into the gas chamber40(seeFIG. 3) through a gap between the right portion74of the housing component164and the spool46to fill up the gas chamber40. Gas also flows into the interior cavity122of the telescoping member120through a gap between the bolt124and the telescoping member120as shown by arrow63. Gas flows to the interior cavity196of the spool46through slot198of the telescoping member120. Gas flows between the distal end of the spool46and the flat end surface80of the housing70of the manifold switching mechanism44but is prevented from exhausting out due to the o-ring50a. Referring still toFIG. 3, gas is also allowed to flow from cavity56to58then to60as shown by arrow64.FIGS. 10 and 11show the flow of gas out of the first gas chamber36through channel66to cavities56,58,60to exhaust19. The compressed gas source15is introduced into the second gas chamber40as discussed above. As compressed gas is introduced into the right gas chamber40, the shaft34and the pistons30,32are shifted to the direction shown by arrow47. Near or at the end of the stroke, the spool46is shifted to the direction shown by arrow47inFIG. 5. The compressed gas source15is now in gas communication with the first gas chamber36. The compressed gas is introduced between rings48a, band routed to channel66to the first gas chamber36. As compressed gas is introduced into the first gas chamber36, the pistons30,32and the shaft34are shifted in the direction of arrow45. Gas within the second gas chamber40is routed to the exhaust19and released to the atmosphere as shown inFIG. 7. From the second gas chamber40, gas is flowed between the telescoping member120and the spool46as shown by arrow65. Gas also may flow to the inner cavity122of the telescoping member120through slot198(seeFIG. 3) as shown by arrow67. InFIG. 7, slot198of the telescoping member120is hidden behind the bolt124. Additionally, to the extent that gas flows between the bolt124and the telescoping member120as shown by arrow69, the gas is exhausted to the atmosphere through exhaust19. The spool valve of the manifold switching mechanism is a three way spool valve which coordinates flow of gas into the gas chambers and to the exhaust.

Referring toFIGS. 5, 13 and 14, when the shaft34and pistons30,32are traversed in the direction of arrow45, liquid from the liquid source11is drawn into the second liquid chamber42and liquid in the first liquid chamber38is pumped out of outlet14. Conversely, when the shaft34and pistons30,32are traversed to the direction of arrow47, liquid from the liquid source11is drawn into first liquid chamber38and liquid in the second liquid chamber42is pumped out of outlet14as shown inFIGS. 2 and 14.FIG. 13is cross section of the pump as shown inFIG. 1.FIG. 14is a schematic of the first and second liquid chambers38,42in relation to the valves100,102,104,106and the liquid inlet and outlet12,14. The compressed gas operates the pump to pump out liquid. The spool46remains in the position shown inFIG. 5during traversal of the shaft34and pistons30,32in the direction of arrow45to allow introduction and venting of gas to the first and second gas chambers36,40. Also, the spool46remains in the position shown inFIG. 2during traversal of the shaft34and pistons30,32in the direction shown by arrow47to allow venting and introduction of gas to the first and second gas chambers36,40. After introduction of gas and venting of the gas of the first and second gas chambers36,40is accomplished as needed, the spool46shifts to the position shown in eitherFIG. 2 or 5.

The manifold switching system44includes the housing72(seeFIG. 3) which is hermetically sealed to a portion74of the housing76of the first and second cylinder26,28with o-ring50. The internal surface78of the housing72of the manifold switching mechanism44is preferably cylindrical and has a flat end surface80. Four circular rings48a-dmay be stacked upon each other to route gas between the rings48a-d.

The rings48a-dare shown inFIGS. 16-23.FIGS. 16 and 17show both sides of ring48d.FIGS. 18 and 19show both sides of ring48c.FIGS. 20 and 21show both sides of ring48b.FIGS. 22 and 23show both sides of ring48a.

The rings48a-dare stacked upon each other and locked into angular position by pins68a, b, cand holes70a, b, c. The side of ring48dshown inFIG. 17abuts the flat end surface80(seeFIG. 3) of the housing72. The ridge82aof ring48dis sealed against the flat end surface80. Such contact creates a generally gas seal to prevent or substantially reduce the flow of gas from the outer periphery of the ring48dto the inner periphery.

The ring48cis shown inFIGS. 18 and 19. Pin68aof the ring48cshown inFIG. 18is inserted into the hole70aof the ring48dshown inFIG. 16. The ridge82bof ring48dis received into the inner periphery of the ridge82cof the ring48c. A generally gas seal is formed between the ridges82b, c. As shown, the ridge82bhas notches84formed as generally semi circular grooves. These notches84are aligned to the notches85shown inFIG. 18. The notches84and85allow gas to flow between the inner cavity of the corresponding rings48a-dand the outer space (e.g., cavity52,56,60, seeFIG. 3). The respective notches84and85in the rings48a-das discussed herein allow gas to travel between the inner cavity (i.e., inner periphery) and the outer cavity (i.e., outer periphery) of the corresponding pair of rings48a-d.

The ring48cshown inFIG. 19also has notches84. The ring48balso has ridges82band notches85as shown inFIG. 20. Pin68bof the ring48bshown inFIG. 20is inserted into the hole70bof the ring48cshown inFIG. 19. The notches84are aligned to the notches85(seeFIGS. 19 and 20) to allow gas communication between the inner and outer cavities of the corresponding rings48a-d.

Moreover, the ring48ahas a pin68c, ridges82band notches85as shown inFIG. 22. The pin68cof the ring48ashown inFIG. 22is inserted into the hole70cof the ring48bshown inFIG. 21. The notches85of the ring48aand the notches84formed in the ridge82aare aligned to each other to provide gas communication between the inner and outer cavities of the corresponding rings48a-d. Ridge86(seeFIG. 23) of the ring48acontacts the portion74of the housing76as shown inFIG. 2.

The stacked rings48a-dare shown inFIG. 24. As shown, the notches84,85form a conduit87that allows gas to flow from the inner cavity of the respective rings48a-dto the outer cavity. The cross sections of the conduits87are shown to allow flow of gas as shown by dash gas line86. Each of the rings48a-dhas an o-ring groove88which receives an o-ring50, as shown inFIG. 24. The o-ring50prevents gas from transferring laterally between rings48a-d. The spool46may be placed in the position shown inFIG. 2.

The housing72of the manifold switching mechanism44may have gas channel90a, b(seeFIGS. 10 and 11). Gas channel90aleads to exhaust19. Gas channel90bas shown inFIG. 10leads to the first gas chamber36. It is plugged or stopped with a plug200to prevent gas from flowing into the exhaust19. As the shaft34and the piston30,32are traversed in the direction of arrow47, the gas within the first gas chamber36flows through channel66out through channel90b, through conduits87formed by notches84,85and through channel90a. The spool46re-routes gas to the conduits87formed by notches84,85of the rings48b, cand rings48c, d. Gas is exhausted out of the exhaust line19. Gas is introduced into the second gas chamber40from the gas source as discussed above. The spool46has a groove92separated by two walls94. The walls94additionally have o-ring grooves96which receive o-rings98. The o-rings98provide a hermetic seal against the interior cylindrical surface89(seeFIG. 25) formed by the stacked rings48a-d.

Referring now toFIGS. 2, 5 and 14, the liquid system of the pump10will be discussed. When the shaft34and pistons30,32are in the position shown inFIG. 2, the second liquid chamber42is filled with liquid and liquid from the first liquid chamber38has been pumped out through the liquid outlet14. As gas is introduced into the second gas chamber40, the shaft34and the pistons30,32are traversed in the direction shown by arrow47. In doing so, positive pressure is created within the second liquid chamber42. The diaphragm check valve100(seeFIG. 14) which is fluidically connected to the second liquid chamber42is opened to allow liquid from the second liquid chamber42to flow out of the liquid outlet14. The input check valve102which is also fluidly connected to the second liquid chamber42remains closed. During this process, a vacuum is created within the first liquid chamber38. The vacuum opens the first input check valve104which is fluidically connected to the liquid source11to introduce liquid from the liquid source11into the first liquid chamber38. Simultaneously, the first output check valve106which is also fluidly connected to the first liquid chamber38remains closed. At the end of the stroke in the direction shown by arrow47(seeFIG. 5), the shaft34and pistons30,32begin their traversal in the direction shown by arrow45. Pressure is created within the first liquid chamber38which causes the first output check valve106(seeFIG. 14) to open in order to pass liquid through the liquid outlet14. The input check valve104remains closed. Simultaneously, the liquid from the liquid source11is introduced into the second liquid chamber42through input check valve102, since the vacuum in created within the second liquid chamber42. Moreover, the second output check valve100remains closed. The check valves100,102,104and106are diaphragm check valves. However, other types of check valves are also contemplated that are known in the art or developed in the future.

The first gas and liquid chambers36,38are separated by the piston30and a flexible barrier108(seeFIG. 2) which provides a seal between the first gas and liquid chambers36,38so that gas is not introduced into the first liquid chamber38and liquid is not introduced into the first gas chamber36. The flexible barrier108may rests on the surface110of the piston30. The flex barrier108is not attached to the surface110of the piston30. An outer periphery of the flex barrier108is secured between the first and middle housing components160,162. Similarly, the second gas and liquid chambers40,42may be separated by piston32and flex barrier112. The flex barrier112may rests on the piston surface114of piston32. An outer periphery of the flex barrier112is secured between the middle and second housing components162,164. The flex barrier112prevents gas from the second gas chamber40from leaking into the second liquid chamber42. Conversely, the flex barrier112prevents liquid from the second liquid chamber42from leaking into the second gas chamber40. The gas system of the pump10is separate from the liquid system. The flex barriers108,112may flex or stretch to the position shown inFIGS. 2 and 5. The flex barriers108and112are not over molded onto the pistons30,32. The flex barriers108and112are not attached to the pistons30,32but is merely in contact with the surfaces110,114. As gas is introduced into the first gas chamber, the gas presses the first flex barrier108against the first piston30. The second piston32is pressing against the second flex barrier112. In reverse, as gas is introduced into the second gas chamber, the gas presses the second flex barrier112against the second piston32. The first piston30is now pressing against the first flex barrier. This structure and arrangement of the flex barriers108,112reduce the cost to manufacture and simplifies the manufacturing process for the pistons30,32and the flex barriers108,112assembly.

The flex barriers108,112may have a circular shape so as to match the interior circular shape of the first and second cylinders26,28. The outer periphery of the flex barriers may have a bead and be trapped between the first and middle housing components160,162and the middle and second housing components162,164at170a, b. The pistons30,32may define the surfaces110,114respectively. The flex barriers108,112are not attached to the surfaces110,114. In one aspect of the pump10, the flex barriers108,112are not molded over the pistons30,32to reduce the cost of manufacturing the pump10. The flex barriers108,112are fabricated from a flexible material but may also be fabricated from an elastomeric material.

Referring now toFIGS. 2-7, the spool46is telescopically connected to the shaft34and pistons30,32. In particular, the spool46has a cylindrical extension116(seeFIG. 3). This cylindrical extension116is received into a mating round aperture118of the portion74of the second housing component164. The inner cavity of the spool46has a lip119which extends around the inner periphery of the spool46. An inner telescoping member120slides longitudinally within the spool46. The telescoping member120has a ridge121which contacts the lip119of the spool46as the shaft34, pistons30and32are traversed in the direction of arrow47. The telescoping member120shifts the spool46toward the position shown inFIG. 5. The telescoping member120additionally has an interior cavity122. A bolt124which is fixedly attached to the second piston32(e.g., threaded attachment) slides within the cavity122. More particularly, a head126of the bolt124is traversed within the interior cavity122. The head126of the bolt124contacts a ledge128of the telescoping member120as the shaft34and pistons30,32are traversed in the direction of arrow47. As the shaft34, pistons30,32are traversed in the direction of arrow47, the bolt124moves in unison with the shaft34. As the shaft34and pistons30,32are traversed in the direction of arrow47, the spool46remains in the position shown inFIG. 2. The head126of the bolt124is traversed within cavity122of the telescoping member120. The head126ultimately contacts the ledge128of the telescoping member120(seeFIG. 4) and begins to move the telescoping member120in the direction of arrow47. A serpentine spring130(seeFIG. 5A) biases the telescoping member120and the spool46toward the position shown inFIG. 2. When the head126of the bolt124contacts the ledge128, the serpentine spring130begins to compress and goes over center176(seeFIG. 4). As soon as the spring130goes over the center, the spring130begins to expand and push the telescoping member120in the direction of arrow47. The ledge121of the telescoping member120contacts the lip119. The spring130pushes the telescoping member120and the spool46in the direction of arrow47as shown inFIG. 5.

As the shaft34and pistons30,32are traversed in the direction of arrow45, head126of the bolt124slide within the interior cavity122of the telescoping member120. The pistons30and32are traversed in the direction of arrow45under the power of the compressed gas as discussed above. The second piston32contacts the telescoping member120as shown inFIG. 6. More particularly, as shown inFIG. 6, the flex barrier112has a footing132which contacts base134of the telescoping member. As the piston32and flex barrier112traverse the telescoping member120in the direction of arrow45, the spring130eventually goes over center176and expands rapidly. The spring130is engaged in a groove136of the telescoping member120(seeFIGS. 5A and 7). The spring130contacts the distal end138of the spool46as shown inFIG. 8. When the spring130expands, the spring130pushes the spool46in the direction of arrow45as shown inFIG. 9. As can be seen, there is a delayed response of the shifting of the spool46until the shaft34and pistons30,32are almost at the end of the stroke. In this way, the gas communication line to the exhaust19and the inlet16remain in the proper configuration to allow gas to be introduced or vented out of the gas chambers36,40as needed.

Referring now toFIGS. 1, 10 and 12, the pump10additionally has a shut off valve18integrated into the body of the pump and shuts off entrance of gas into the first gas chamber36to stop operation of the pump. The shut off valve18when actuated, shuts off the flow of air through gas channel66(seeFIG. 10). As shown inFIG. 12, the pin140and rubber seal141are normally retracted from channel66. When the liquid source11is empty, a vacuum is created at the inlet12. This vacuum is communicated to cavity142between button20and a shut off valve housing wall144. The vacuum overcomes a bias force of spring146. The spring146biases the button120and the pin140to the retracted position as shown inFIG. 12. The vacuum, when present, urges the pin140and the seal141into the channel66and shuts off the flow of air within channel66. The rubber seal141has a mushroom configuration to allow gas to exhaust out of the first gas chamber36but not enter the first gas chamber36when the seal141and pin140are urged into the channel66. When the operation of the pump is stopped, the pistons30,32continue to cycle until it reaches the position shown inFIG. 5. This protects the pump from an internal high load situation. The operation of the pump10is also stopped since compressed gas is no longer allowed to flow through the pump10. The user can lock the button20in the extended position through a 90° twist lock mechanism of the button20. The liquid source11can be replaced with a new liquid source11. The button20can be disengaged to allow compressed gas to flow back through the system of the pump10and begin operation of the pump10. Alternatively, the shutoff valve18can be manually pressed by depressing the button20in the direction of arrow148and locked with the twist lock mechanism by hand.

More particularly, referring toFIG. 12, the auto shut off valve18may include the housing wall144, an exterior housing180, and the button20. The housing wall144may have a cylindrical shape with the cross section shown inFIG. 12. The housing wall144may be secured to one or more of the first, middle or second housing components160,162,164as the case may be in optimizing the design of the pump10. The housing wall144may have an aperture182which receives actuating pin140. The actuating pin140is held in place by the aperture182and reciprocates within the aperture182. The distal end of the pin184holds the rubber seal141within the groove as shown. The housing wall144may also have spring seat structure184to hold a spring146in place. The spring146may be a helical coil compression spring which biases the button20and a base190of the rubber seal141in the retracted position as shown inFIG. 12. The o-rings50identified and shown inFIG. 12provide a hermetic seal. The exterior housing180of the shut off valve18may be mounted onto the housing wall144. The rubber seal188may be disposed on the other side of the spring146. The spring146pushes against the base190of the rubber seal188to bias the base190to the retracted position. As shown, the pin140is engaged to the base190of the rubber seal by way of c-ring192. Also, the pin140is received through aperture194of the base190and may extend to the button20. The outer periphery of the rubber seal188has a bead194that is trapped between the housing wall144and the exterior housing180. The cavity142is hermetically sealed and is in fluid communication with the fluid inlet12so that when liquid is completely emptied out of the liquid source11, the vacuum created at the liquid inlet12is communicated to the cavity142.

The button20is seated within the exterior housing180. The base190of the rubber seal188is seated on the button20so that the button20and the base190of the rubber seal188move in unison.

The pump10as shown inFIG. 2may have at least four different housing components, namely, a first housing component160, middle housing component162and second housing component164. The middle housing component162may have a plurality of threaded holes166which receive bolts168which attach the first and second housing components160,164to the middle housing component162. Moreover, the junction170a, bbetween the first and second housing components160,164and the middle housing component162may receive an outer periphery (e.g., bead) of the flex barriers108,112to provide a hermetic seal. The first piston30may be screwed on to the shaft34at the threaded connection172. Bearings175may allow the shaft34to be traversed linearly and reciprocally within the first and second cylinders26,28. O-ring177seals the common wall29and shaft34so that liquid is not transferred between the first and second liquid chambers38,42. The pistons30,32and the shaft34may be circular from the end view. Likewise, the interior surface of the cylinders26,28may also have a matching cylindrical configuration to house the first and second pistons30,32. The second piston32may be fabricated as a unitary structure with the shaft34. As shown, as the shaft34and pistons30,32reciprocate in directions45and47, the bearings175provide for smooth sliding or traversal of the shaft34and the O-ring177seals the first and second liquid chambers38,42. The housing76may additionally have a housing72for the manifold switching mechanism44. The housing72has a cylindrical internal surface. The rings48a-dand the O-ring50that make up the internal surface of the housing72may also be circular. The same is true for the spool46, intermediate telescoping member120and the bolt124.

Spring130has a serpentine configuration. Two serpentine springs130, one on each side of the intermediate telescoping member120are engaged into the second housing component164and the intermediate telescoping member120. The serpentine springs130are shown inFIGS. 5A and 10. Also, as shown inFIG. 10, the second piston32bumps up against the second housing component164at the end of the stroke in the direction of arrow45. The intermediate telescoping member may have a groove136on opposed sides that receive and hold the distal end of the serpentine spring130(seeFIG. 7). The opposed side of the serpentine spring130may be engaged into grooves174a, b(seeFIG. 6) or receptacles174formed in the second housing component164. The grooves174a, bdefine a plane176. The medial ends of the springs130cross the plane176as the intermediate telescoping member120is being traversed in the direction of arrow47or in the direction of arrow45as discussed above. When the pistons30,32and the shaft34are traversed in the direction of arrow47, the groove136approaches the plane176. The movement is caused by the compressed gas as discussed above. However, when the grooves136cross the plane176, the springs130rapidly expand and shift the spool46in the direction of arrow47as discussed above under the power of the springs130. Conversely, when the pistons30,32and the shaft34are being traversed in the direction of arrow45, the footing132of the flex barrier112contacts the base134of the intermediate telescoping member120to begin pushing the intermediate telescoping member120in the direction of arrow45. The grooves136approach the plane176from the opposite side under the power of the compressed gas being filled into the first gas chamber36. After the grooves136cross the plane176, the springs130rapidly expand and push the telescoping member120and the spool46in the direction of arrow45as discussed above.

Referring now toFIG. 2, the spool46is held in the stationary position or trapped between the spring130and the flat end surface80of the housing72of the manifold switching mechanism44. As compressed gas is introduced into the second gas chamber40, the bolt124is traversed in the direction of arrow47. The head126of the bolt124contacts the ledge128of the telescoping member120and pushes the telescoping member120in the direction of arrow47as well. This also traverses the groove136which holds the medial distal ends of the springs130across the plane176. When the spring angle150(seeFIG. 4) is at 4°, the ledge121of the telescoping member120is still not in contact with the lip119of the spool46. At this point, the pistons30,32are a distance178(i.e., 0.125 inch) away from the first housing component160and the common wall29. When the spring angle150is at 5°, the ledge121of the telescoping member120contacts the lip119of the spool46. When the groove136crosses over plane176, the springs130expands rapidly and pushes the intermediate telescoping member120and the spool46in the direction of arrow47as shown inFIG. 5.

As discussed above, gas is introduced into the first gas chamber36and traverses the pistons30,32and the shaft34in the direction of arrow45. As the footing132of the flex barrier112contacts and pushes the intermediate telescoping member120in the direction of arrow45, the groove136crosses over the plane176. When the spring angle151(seeFIG. 6) is at 4°, the springs130do not contact the spool46, as shown inFIG. 7. At a spring angle151of 5°, the springs130contacts the spool46and begins to move the spool46in the direction of arrow45under the power of the springs130. The springs130traverse the spool46in the direction of arrow45as shown inFIG. 9.

The first and second gas chambers36,40are in gas communication with the gas inlet16and the gas outlet17through internal channels formed in one or more of the first, middle, second housing components160,162,164and the housing72of the manifold switching mechanism44and other parts of the pump10as needed. Moreover, the first and second liquid chambers38,42are in fluid communication with liquid inlet and outlet12,14through internal channels formed in one or more of the first, middle, second housing components160,162,164and the housing72of the manifold switching mechanism44and other parts of the pump10as needed. Although internal gas and liquid communications lines are depicted and discussed, it is also contemplated that external separate gas and liquid tubes may used to route the liquid and gas to the respective liquid inlet and outlet12,14and the gas inlet and outlet16,17.