Fixed volume valve system
Embodiments of the present invention provide valves that provide for uniform holdup volume. An embodiment of the present invention provides a valve comprising a valve body (e.g., one or more pieces) that defines a valve chamber having a valve seat, an inlet flow passage, an outlet flow passage and a diaphragm control flow passage intersecting the valve seat. The valve seat is shaped so that the valve has a fixed holdup volume when at least a threshold vacuum is applied to the diaphragm control flow passage. The valve further comprises a diaphragm movable towards and away from the valve seat. According to one embodiment of the present invention, the valve seat can have a semi-hemispherical shape to which the diaphragm conforms when a minimum vacuum is applied to the diaphragm control flow passage.
The present application claims under 35 U.S.C. 119(e) priority to and the benefit of U.S. Provisional Application No. 60/742,147, entitled “VALVE PLATE SYSTEM AND METHOD” by Iraj Gashgaee et al., filed Dec. 2, 2005, [Atty. Dkt. No. ENTG1770] which is hereby fully incorporated by reference herein.
TECHNICAL FIELD OF THE INVENTIONThis invention relates generally fluid valves. More particularly, embodiments of the present invention relate to valves for multi-stage pumps. Even more particularly, embodiments of the present invention relate to a valve plate that reduces hold up volume.
BACKGROUND OF THE INVENTIONThere are many applications for which precise control over the amount and/or rate at which a fluid is dispensed by a pumping apparatus is necessary. In semiconductor processing, for example, it is important to control the amount and rate at which photochemicals, such as photoresist chemicals, are applied to a semiconductor wafer. The coatings applied to semiconductor wafers during processing typically require a flatness across the surface of the wafer that is measured in angstroms. The rate at which processing chemicals are applied to the wafer has to be controlled in order to ensure that the processing liquid is applied uniformly.
The repeatability of a dispense operation is effected, in part, by precisely controlling the amount of fluid in various portions of the multi-stage pumps at different stages in the dispense cycle. Some valve designs, however, exhibit characteristics that reduce repeatability. In many multi-stage pumps, the hold up volume of a valve (i.e., the volume of fluid in the valve when the valve is open) depends largely on the pressure/vacuum used to open the valve. As the pressure/vacuum increases, the amount of hold up volume also increases. When the valve closes, the hold up volume of fluid is forced elsewhere in the pump, such as to a pump chamber. Thus, the amount of fluid entering another portion of the pump due to a valve closing varies depending on the amount of pressure/vacuum applied to open the valve.
The house pressure/vacuum used to open the valves is often not well controlled relative to the precision required in semiconductor manufacturing. Hence, during each dispense operation, a different amount of fluid may be in the dispense chamber due to the variable hold up volumes of pump valves. The repeatability of the dispense operation is consequently reduced.
SUMMARY OF THE INVENTIONEmbodiments of the present invention provide valve systems and methods that substantially eliminate or reduce the disadvantages of previously developed valve systems and methods. More particularly, one embodiment of the present invention provides a valve comprising a valve body (e.g., one or more pieces) that defines a valve chamber having a valve seat, an inlet flow passage, an outlet flow passage and a diaphragm control flow passage intersecting the valve seat. The valve seat is shaped so that the valve has a fixed holdup volume when at least a threshold vacuum is applied to the diaphragm control flow passage. The valve further comprises a diaphragm movable towards and away from the valve seat. According to one embodiment of the present invention, the valve seat can have a semi-hemispherical shape to which the diaphragm conforms when a minimum vacuum is applied to the diaphragm control flow passage. It should be noted that the “semi-hemispherical” shape, for purposes of this application, can include a full hemisphere.
Another embodiment of the present invention comprises a valve assembly having a valve (e.g., a purge valve or other valve). The valve assembly comprises a first piece, such as a pump body, and a second piece, such as a valve plate, coupled together. The valve body defines a valve chamber. The first piece of the valve body defines a first flow passage (e.g., an inlet flow passage) and a second flow passage (e.g., an outlet flow passage) intersecting the valve chamber and the second piece defines a valve seat and a third flow passage (e.g., a diaphragm control flow passage) intersecting the first valve seat. The valve assembly further comprises a valve diaphragm movable within the valve chamber. The valve seat is shaped so that the valve diaphragm conforms to the valve seat to provide a fixed valve holdup volume when a threshold or greater vacuum is applied to the third flow passage.
Yet another embodiment of the present invention comprises a multistage pump having a feed chamber and a dispense chamber. The multistage pump comprises a pump body and a valve plate. The pump body defines an inlet flow passage to and an outlet flow passage from a first valve and the valve plate defines a valve seat for the first valve. The multi-stage pump further comprises a valve diaphragm movable in the first valve. According to one embodiment the first valve seat is shaped so that the first valve diaphragm conforms to the first valve seat to provide a fixed holdup volume when a threshold or greater vacuum is applied to the first valve. The valve plate and pump body can also define other valves used to regulate flow in the multistage pump.
Embodiments of the present invention provide an advantage by eliminating or reducing the variability of hold up volume caused by outside influences. For example, embodiments of the present invention provide an advantage by reducing the effects of vacuum pressure on the displacement volume of a valve.
Embodiments of the present invention provide yet another advantage by reducing the hold up volume of a valve.
Embodiments of the present invention provide yet another advantage by increasing diaphragm life through reduced stress on the diaphragm.
BRIEF DESCRIPTION OF THE DRAWINGSA more complete understanding of the present invention and the advantages thereof may be acquired by referring to the following description, taken in conjunction with the accompanying drawings in which like reference numbers indicate like features and wherein:
Preferred embodiments of the present invention are illustrated in the FIGUREs, like numerals being used to refer to like and corresponding parts of the various drawings. To the extent dimensions are provided, they are provided by way of example for particular implementations and are not provided by way of limitation. Embodiments can be implemented in a variety of configurations.
Broadly speaking, embodiments of the present invention provide valves that are configured to have a fixed hold up volume once a threshold condition is met. For example, the valves can be configured to have a fixed holdup volume once a threshold pressure/vacuum is applied to open the valve.
According to one embodiment a valve can comprise a valve body defining a valve chamber having a valve seat, an inlet flow passage, an outlet flow passage and a diaphragm control flow passage. The valve body, according to one embodiment, can be made of multiple pieces such as a pump body and a valve plate. A diaphragm is movable towards and away from the valve seat based on the application of pressure/vacuum to the diaphragm control flow passage. The valve seat is shaped so that the valve has a fixed holdup volume when at least a threshold vacuum is applied to the diaphragm control flow passage. For example, the valve seat can have a semi-hemispherical shape to which the diaphragm conforms when the valve is open.
According to various embodiments, various valves with fixed holdup volumes can be at least partially integrated into a valve plate of a multi-stage pump used for dispensing chemicals to a wafer. The valve plate and pump body can sandwich a diaphragm that acts as the diaphragm for one or more of the valves of the multi-stage pump.
Feed stage 105 and dispense stage 110 can include rolling diaphragm pumps to pump fluid in multi-stage pump 100. Feed-stage pump 150 (“feed pump 150”), for example, includes a feed chamber 155 to collect fluid, a feed stage diaphragm 160 to move within feed chamber 155 and displace fluid, a piston 165 to move feed stage diaphragm 160, a lead screw 170 and a stepper motor 175. Lead screw 170 couples to stepper motor 175 through a nut, gear or other mechanism for imparting energy from the motor to lead screw 170. According to one embodiment, feed motor 170 rotates a nut that, in turn, actuates lead screw 170, causing piston 165 to actuate. Dispense-stage pump 180 (“dispense pump 180”) can similarly include a dispense chamber 185, a dispense stage diaphragm 190, a piston 192, a lead screw 195, and a dispense motor 200. According to other embodiments, feed stage 105 and dispense stage 110 can each be include a variety of other pumps including pneumatically actuated pumps, hydraulic pumps or other pumps. One example of a multi-stage pump using a pneumatically actuated pump for the feed stage and a stepper motor driven hydraulic pump is described in U.S. patent application Ser. No. 11/051,576, entitled “PUMP CONTROLLER FOR PRECISION PUMPING APPARATUS” by Inventors Zagars, et al., filed Feb. 4, 2005, [Atty. Dkt. No. ENTG1420-2], which is hereby fully incorporated by reference herein.
Feed motor 175 and dispense motor 200 can be any suitable motor. According to one embodiment, dispense motor 200 is a Permanent-Magnet Synchronous Motor (“PMSM”). The PMSM can be controlled by a digital signal processor (“DSP”) utilizing Field-Oriented Control (“FOC”) or other position/speed control scheme at motor 200, a controller onboard multi-stage pump 100 or a separate pump controller. PMSM 200 can further include an encoder (e.g., a fine line rotary position encoder) for real time feedback of dispense motor 200's position. The use of a position sensor gives accurate and repeatable control of the position of piston 192, which leads to accurate and repeatable control over fluid movements in dispense chamber 185. For, example, using a 2000 line encoder, which according to one embodiment gives 8000 pulses to the DSP, it is possible to accurately measure to and control at 0.045 degrees of rotation. In addition, a PMSM can run at low velocities with little or no vibration. Feed motor 175 can also be a PMSM or a stepper motor. U.S. Provisional Patent Application No. 60/741,660 entitled “SYSTEM AND METHOD FOR POSITION CONTROL OF A MECHANICAL PISTON IN A PUMP” by Gonnella et al., filed Dec. 2, 2005, [Atty. Dkt. No. ENTG1750], U.S. Provisional Patent Application No. 60/841,725, entitled “SYSTEM AND METHOD FOR POSITION CONTROL OF A MECHANICAL PISTON IN A PUMP”, by Gonnella et al., filed Sep. 1, 2006 [Atty. Dkt. No. ENTG1750-1] and U.S. patent application Ser. No. ______, entitled “SYSTEM AND METHOD FOR POSITION CONTROL OF A MECHANICAL PISTON IN A PUMP”, by Inventors Gonnella et al., filed ——————, [Atty. Dkt. No. ENTG1750-2], which are hereby incorporated by reference herein, describe embodiments of a pump utilizing a PMSM, which is hereby fully incorporated by reference herein. According to one embodiment, feed motor 175 can be an EAD Motors of Dover, N.H. stepper motor part no. L1 LAB-005 and dispense motor 200 can be an EAD Motors brushless DC Motor part no. DA23 DBBL-13E17A.
The valves of multi-stage pump 100 are opened or closed to allow or restrict fluid flow to various portions of multi-stage pump 100. According to one embodiment, these valves can be pneumatically actuated (i.e., gas driven) diaphragm valves that open or close depending on whether pressure or a vacuum is asserted. One embodiment of a valve plate for housing diaphragm valves is described below in conjunction with
Dispense block 205 can include various external inlets and outlets including, for example, inlet 210 through which the fluid is received, vent outlet 215 for venting fluid during the vent segment, and dispense outlet 220 through which fluid is dispensed during the dispense segment. Dispense block 205, in the example of
Dispense block 205 routes fluid to the feed pump, dispense pump and filter 120. A pump cover 225 can protect feed motor 175 and dispense motor 200 from damage, while piston housing 227 can provide protection for piston 165 and piston 192. Valve plate 230 provides a valve housing for a system of valves (e.g., inlet valve 125, isolation valve 130, barrier valve 135, purge valve 140 and vent valve 145 of
Valve plate 230 includes a valve control inlet for each valve to apply pressure or vacuum to the corresponding diaphragm. For example, inlet 235 corresponds to barrier valve 135, inlet 240 to purge valve 140, inlet 245 to isolation valve 130, inlet 250 to vent valve 145, and inlet 255 to inlet valve 125. By the selective application of pressure or vacuum to the inlets, the corresponding valves are opened and closed. The valves can be opened and closed in various sequences such as described in United States patent Application Nos. U.S. Provisional Patent Application No. 60/742,168, entitled “SYSTEM AND METHOD FOR VALVE SEQUENCING IN A PUMP”, by inventors Gonnella et al., filed Dec. 2, 2005, [Atty. Dkt. No. ENTG1740] and U.S. patent application Ser. No. ______, entitled “SYSTEM AND METHOD FOR VALVE SEQUENCING IN A PUMP”, by Inventors Gonnella et al., filed ——————, [Atty. Dkt. No. ENTG1740-1], which are hereby fully incorporated by reference herein. Valve plate 230 can be configured to reduce the hold-up volume of the valves, eliminate volume variations due to vacuum fluctuations, reduce vacuum requirements and reduce stress on the valve diaphragm.
A valve control gas and vacuum are provided to valve plate 230 via valve control supply lines 260, which run from a valve control manifold (covered by manifold cover 263 or housing cover 225), through dispense block 205 to valve plate 230. Valve control gas supply inlet 265 provides a pressurized gas to the valve control manifold and vacuum inlet 270 provides vacuum (or low pressure) to the valve control manifold. The valve control manifold acts as a three way valve to route pressurized gas or vacuum to the appropriate inlets of valve plate 230 via supply lines 260 to actuate the corresponding valve(s).
According to one embodiment, dispense pump and/or feed pump 150 can be a rolling diaphragm pump as described in U.S. Provisional Patent Application No. 60/742,435, entitled “SYSTEM AND METHOD FOR MULTI-STAGE PUMP WITH REDUCED FORM FACTOR” by Gonnella et al, filed Dec. 5, 2005, [Atty. Dkt. No. ENTG1720], and U.S. patent application Ser. No. ______, entitled “SYSTEM AND METHOD FOR A PUMP WITH REDUCED FORM FACTOR”, by inventors Cedrone et al., filed ——————, [Atty. Dkt. No. ENTG1720-1] which are hereby fully incorporated by reference herein. It should be noted that the multi-stage pump 100 described in conjunction with
A flow passage is defined for each valve for the application of a valve control gas/vacuum or other pressure to cause the diaphragm to be displaced between an open position and closed position for a valve. As an example, flow passage 1050 runs from an input on valve control plate 230 to the corresponding opening in the arced surface of purge valve chamber 1040. By selective application of vacuum or low pressure through flow passage 1050, diaphragm 1002 can be displaced into chamber 1040, thereby causing purge valve 140 to open. An annular ring around each valve chamber provides for sealing with O-rings 1004. For example, annular ring 1055 is used to partially contain an o-ring to seal purge valve 140.
In the embodiment of
When positive pressure is applied through flow passage 1065, diaphragm 1002 moves to seal the inlet and outlet (in this case flow passage 300 from the dispense chamber and flow passage 305 to the feed chamber). The volume of fluid in area 1072 will therefore be moved out of purge valve 140. This will cause a pressure spike in the dispense chamber (or other enclosed space to which the fluid is moved). The amount of fluid displaced by the valve will depend on how much volume was held up in the valve. Because this volume varies with the amount of pressure applied, different pumps of the same design, but operating using different vacuum pressures, will show different pressure spikes in the dispense chamber or other enclosed space. Moreover, because diaphragm 1002 is plastic, the displacement of diaphragm 1002 for a given vacuum pressure will vary depending on temperature. Consequently, the volume of unused area 1070 will change depending on temperature. Because the displacement volume of the valve of
Embodiments of the present invention reduce or eliminate the problems associated with a valve chamber having a flat surface.
In the embodiment of
The valve chamber can be sized to allow the diaphragm to displace sufficiently to allow fluid flow from the inlet to the outlet path (e.g., from flow path 300 to flow path 305 of
It should also be noted that flow passage 1050 for the application of pressure/vacuum to the diaphragm does not have to be centered in the valve chamber, but may be off center (this is shown, for example, on the barrier valve chamber 1035 in
However, the positioning of these flow passages with respect to the valve can be reversed or otherwise changed in other embodiments so that less fluid is displaced back to the dispense chamber than displaced to the feed chamber when purge valve 140 closes. For inlet valve 125, on the other hand, the inlet flow passage can be closer to the center so that more fluid is displaced back to the fluid source than to the feed chamber when inlet valve 125 is closed (i.e., inlet valve 125 can have the inlet/outlet flow path arrangement shown in
Other configurations of inlet and outlet flow passages can also be utilized. For example, both the inlet and outlet flow passage to a valve can be off center. As another example, the widths of the inlet and outlet flow passages can be different so that one flow passage is more restricted, again helping to cause more fluid to be displaced through one of the flow passages (e.g., the larger flow passage) when the valve closes.
As can be seen from
The valves of valve plate 230 may have different dimensions. For example, the purge valve 140 can be smaller than the other valves or the valves can be otherwise dimensioned.
The size of each valve can be selected to balance the desire to minimize the pressure drop across the valve (i.e., the desire to minimize the restriction caused by the valve in the open position) and the desire to minimize the amount of hold up volume of the valve. That is, the valves can be dimensioned to balance the desire for minimally restricted flow and to minimize pressure spikes when the valve opens/closes. In the examples of
Although described in terms of a multi-stage pump, embodiments of the present invention can also be utilized in a single stage pump.
Dispense block 4005 can include various external inlets and outlets including, for example, inlet 4010 through which the fluid is received, purge/vent outlet 4015 for purging/venting fluid, and dispense outlet 4020 through which fluid is dispensed during the dispense segment. Dispense block 4005, in the example of
Dispense block 4005 routes fluid from the inlet to an inlet valve (e.g., at least partially defined by valve plate 4030), from the inlet valve to the pump chamber, from the pump chamber to a vent/purge valve and from the pump chamber to outlet 4020. A pump cover 4225 can protect a pump motor from damage, while piston housing 4027 can provide protection for a piston and, according to one embodiment of the present invention, be formed of polyethylene or other polymer. Valve plate 4030 provides a valve housing for a system of valves (e.g., an inlet valve, and a purge/vent valve) that can be configured to direct fluid flow to various components of pump 4000. Valve plate 4030 and the corresponding valves can be formed similarly to the manner described in conjunction with valve plate 230, discussed above. The purge valve can be the same size as, smaller than or larger than the inlet valve. Using a smaller purge valve, however, can reduce the holdup volume returned to the chamber as described above. According to one embodiment, each of the inlet valve and the purge/vent valve is at least partially integrated into valve plate 4030 and is a diaphragm valve that is either opened or closed depending on whether pressure or vacuum is applied to the corresponding diaphragm. In other embodiments, some of the valves may be external to dispense block 4005 or arranged in additional valve plates. According to one embodiment, a sheet of PTFE is sandwiched between valve plate 4030 and dispense block 4005 to form the diaphragms of the various valves. Valve plate 4030 includes a valve control inlet (not shown) for each valve to apply pressure or vacuum to the corresponding diaphragm.
Thus, embodiments of the present invention provide a valve design that reduces variations in displacement volume. According to various embodiments of the present invention, a valve body can define a valve chamber with a valve seat shaped to provide a fixed holdup volume. For example, the valve plate can have a semi-hemispherical shape to which the valve diaphragm conforms when a minimum vacuum is applied to the diaphragm. That is, the diaphragm substantially lines the inside of the semi-hemispherical surface when the valve is in the open position. It should be noted that the outer edge of the valve chamber does not have to be round, but can be elliptical or other shape. The surface of the valve chamber towards which the diaphragm displaces, however, is preferably shaped so that, when the diaphragm is displaced, the diaphragm takes the shape of that surface. Thus, the valve chamber can have a shape such that the diaphragm takes a known volume when the diaphragm is displaced (i.e., a shape that creates a fixed volume when the valve is open).
Although the present invention has been described in detail herein with reference to the illustrative embodiments, it should be understood that the description is by way of example only and is not to be construed in a limiting sense. For example, dimensions are not to be construed in a limiting sense. It is to be further understood, therefore, that numerous changes in the details of the embodiments of this invention and additional embodiments of this invention will be apparent to, and may be made by, persons of ordinary skill in the art having reference to this description. It is contemplated that all such changes and additional embodiments are within the scope of this invention.
Claims
1. A valve comprising:
- a valve body defining: a valve chamber having a valve seat; an inlet flow passage; an outlet flow passage; a diaphragm control flow passage, wherein the diaphragm control flow passage intersects the valve seat; and
- a diaphragm movable towards and away from the valve seat, wherein the diaphragm control flow passage is separated from the inlet flow passage and the outlet flow passage by the diaphragm; and
- wherein the valve seat is shaped so that the valve has a fixed holdup volume when at least a threshold vacuum is applied to the diaphragm control flow passage.
2. The valve of claim 1, wherein the valve seal conforms to the valve seat shape when at least the threshold vacuum is applied to the pressure control passage.
3. The valve of claim 1, wherein the valve seat has a semi-hemispherical shape.
4. The valve of claim 3, wherein the valve body comprises multiple pieces.
5. The valve of claim 4, wherein a first portion of the valve body comprises a dispense block defining the inlet and outlet flow passages and a second portion of the valve body comprises a valve plate defining the valve seat and the diaphragm control flow passage.
6. The valve of claim 6, wherein the diaphragm is sandwiched between the dispense block and the valve plate.
7. The valve of claim 6, further comprising an o-ring at least partially disposed in a first annular ring defined in the valve plate, wherein the o-ring contacts the diaphragm.
8. The valve of claim 7, wherein the dispense block comprises a second annular ring, wherein the diaphragm is partially disposed in the second annular ring.
9. The valve of claim 5, wherein the inlet flow passage leads to a dispense chamber of a multi-stage pump.
10. The valve of claim 9, wherein the inlet flow passage intersects the valve chamber at a center axis.
11. The valve of claim 9, wherein the outlet flow passage intersects the valve chamber at a center axis.
12. The valve of claim 9, wherein the inlet and outlet flow passage are both off-center.
13. The valve of claim 9, wherein the inlet flow passage and outlet flow passage are different sizes.
14. A valve assembly having a first valve, the valve assembly comprising:
- a valve body comprising a first piece coupled to a second a piece, wherein the first piece and the second piece define a first valve chamber, further wherein the first piece defines a first flow passage and a second flow passage intersecting the valve chamber and the second piece defines a first valve seat and a third flow passage intersecting the first valve seat; and
- a first valve diaphragm movable within the valve chamber, wherein the first and second flow passages are separated from the third flow passage by the first valve diaphragm;
- wherein the first valve seat is shaped so that the first valve diaphragm conforms to the first valve seat to provide a fixed first valve holdup volume when a threshold or greater vacuum is applied to the third flow passage.
15. The valve assembly of claim 15, wherein the valve seat has a semi-hemispherical shape.
16. The valve assembly of claim 14, further comprising a second valve having a second valve chamber.
17. The valve assembly of claim 16, wherein the first portion of the valve body defines a fourth flow passage and a fifth flow passage, the fourth and fifth flow passages intersecting the second valve chamber;
- wherein the second portion of the valve body defines the second valve seat and defines a sixth flow passage intersecting the second valve seat; and
- wherein the second valve seat is shaped so that a second valve diaphragm conforms to the second valve seat to provide a fixed second valve holdup volume when a threshold or greater vacuum is applied to the sixth flow passage.
18. The valve assembly of claim 17, wherein first valve seat and the second valve seat have semi-hemispherical shapes.
19. The valve assembly of claim 17, further comprising an sheet of electrometric material coupled between the first portion of the valve body and the second portion of the valve body and wherein the first valve diaphragm is a first portion of the sheet of elastomeric material and the second valve diaphragm is a second portion of the sheet of elastomeric material.
20. The valve assembly of claim 19, further comprising a first o-ring at least partially disposed in a first annular ring about the first valve seat and a second o-ring at least partially disposed about the second valve seat.
21. The valve assembly of claim 17, wherein the first valve is a purge valve for a multistage pump.
22. The valve assembly of claim of claim 21, wherein the second valve is one of an inlet valve, isolation valve, barrier valve or vent valve for a multistage pump.
23. A multistage pump having a feed chamber and a dispense chamber, the multistage pump comprising:
- a pump body defining an inlet flow passage to and an outlet flow passage from a first valve;
- a valve plate coupled to the dispense body, the valve plate defining a first valve seat for the first valve;
- a first valve diaphragm movable in the first valve; and
- wherein the first valve seat is shaped so that the first valve diaphragm conforms to the first valve seat to provide a fixed first valve holdup volume when a threshold or greater vacuum is applied to the first valve.
24. The multistage pump of claim 23, wherein the inlet flow passage to the first valve leads from the dispense chamber to the first valve.
25. The multistage pump of claim 24, wherein an entrance to the inlet flow passage to the first valve is coaxial with a center axis of the first valve seat and an entrance to the outlet flow passage of the first valve is non-coaxial with the center axis of the first valve seat.
26. The multistage pump of claim 24, wherein the entrance to the inlet flow passage to the first valve is non-coaxial with a center axis of the first valve seat and an entrance to the outlet flow passage of the first valve is coaxial with the center axis of the first valve seat.
27. The multistage pump of claim 24, wherein the inlet flow passage to the first valve has a smaller cross-section than a cross-section of the outlet flow passage of the first pump.
28. The multistage pump of claim 24, further comprising:
- an inlet valve diaphragm movable in an inlet valve;
- an isolation valve diaphragm movable in an isolation valve;
- a barrier valve diaphragm movable in a barrier valve;
- a vent valve diaphragm movable in a vent valve; and
- the pump body further defining a set of flow passages proving an inlet flow passage to and an outlet flow passage from each of an inlet valve, an isolation valve, a barrier valve and a vent valve;
- the valve plate further comprising, a valve seat for the inlet valve, a valve seat for the isolation valve, a valve seat for the barrier valve and a valve seat for the vent valve; and
- wherein the first valve is a purge valve.
29. The multistage pump of claim 28, wherein the inlet valve seat is shaped so that the inlet valve diaphragm conforms to the shape of the inlet valve seat when the threshold or greater vacuum is applied to the inlet valve.
30. The multistage pump of claim 29, wherein the inlet valve is larger than the purge valve.
31. The multistage pump of claim 29, wherein:
- the vent valve seat is shaped so that the vent valve diaphragm conforms to the shape of the vent valve seat when the threshold or greater vacuum is applied to the vent valve;
- the barrier valve seat is shaped so that the barrier valve diaphragm conforms to the shape of the barrier valve seat when the threshold or greater vacuum is applied to the barrier valve; and
- the isolation valve seat is shaped so that the isolation valve diaphragm conforms to the shape of the isolation valve seat when the threshold or greater vacuum is applied to the isolation valve.
32. The multistage pump of claim 31, wherein each of the first valve seat, vent valve seat, inlet valve seat, isolation valve seat and barrier valve seat have a semi-hemispherical shape.
33. The multistage pump of claim 28, wherein the first valve diaphragm, vent valve diaphragm, barrier valve diaphragm, inlet valve diaphragm and isolation valve diaphragm are portions of a single sheet of elastomeric material coupled between the valve plate and the pump body.
34. The multistage pump of claim 23, wherein the first flow passage leads from the dispense chamber to the first valve and the second flow passage leads from the first valve to the feed chamber.
Type: Application
Filed: Nov 20, 2006
Publication Date: Jun 7, 2007
Inventors: Iraj Gashgaee (Marlborough, MA), James Cedrone (Braintree, MA), George Gonnella (Pepperell, MA)
Application Number: 11/602,457
International Classification: F04B 53/10 (20060101);