The present invention relates generally to positive displacement devices. More particularly, embodiments of the present invention relate to bellows plungers for use in reciprocating devices (e.g., pumps, valves, etc.), reciprocating pumps including such bellows plungers, and to methods of forming bellows plungers.
Reciprocating fluid pumps are used in many industries. Reciprocating fluid pumps generally include two fluid chambers in a pump body. A reciprocating piston or shaft is driven back and forth within the pump body. One or more diaphragms or bellows plungers may be connected to the reciprocating piston or shaft. As the reciprocating piston moves in one direction, the movement of the diaphragms or bellows plungers results in fluid being drawn into a first fluid chamber of the two fluid chambers and expelled from the second chamber. As the reciprocating piston moves in the opposite direction, the movement of the diaphragms or bellows plungers results in fluid being expelled from the first chamber and drawn into the second chamber. A chamber inlet and a chamber outlet may be provided in fluid communication with the first fluid chamber, and another chamber inlet and another chamber outlet may be provided in fluid communication with the second fluid chamber. The chamber inlets to the first and second fluid chambers may be in fluid communication with a common single pump inlet, and the chamber outlets from the first and second fluid chambers may be in fluid communication with a common single pump outlet, such that fluid may be drawn into the pump through the pump inlet from a single fluid source, and fluid may be expelled from the pump through a single pump outlet. Check valves may be provided at the chamber inlet and outlet of each of the fluid chambers to ensure that fluid can only flow into the fluid chambers through the chamber inlets, and fluid can only flow out of the of the fluid chambers through the chamber outlets.
Examples of such reciprocating fluid pumps are disclosed in, for example, U.S. Pat. No. 5,370,507, which issued Dec. 6, 1994 to Dunn et al., U.S. Pat. No. 5,558,506, which issued Sep. 24, 1996 to Simmons et al., U.S. Pat. No. 5,893,707, which issued Apr. 13, 1999 to Simmons et al., U.S. Pat. No. 6,106,246, which issued Aug. 22, 2000 to Steck et al., U.S. Pat. No. 6,295,918, which issued Oct. 2, 2001 to Simmons et al., U.S. Pat. No. 6,685,443, which issued Feb. 3, 2004 to Simmons et al., and U.S. Pat. No. 7,458,309, which issued Dec. 2, 2008 to Simmons et al., the disclosure of each of which is incorporated herein in its entirety by this reference.
In some embodiments, the present invention includes bellows plungers having a tubular body. The tubular body includes a side wall having a shape defining at least one ridge extending continuously and helically about a longitudinal axis of the tubular body from a location proximate a first closed end of the body to a location proximate an opposite, second open end of the body.
In additional embodiments, the present invention includes reciprocating fluid pumps for pumping a subject fluid. The pumps include a pump body, at least one subject fluid chamber within the pump body, and at least one bellows plunger located at least partially within the pump body. A surface of the bellows plunger defines a surface of the subject fluid chamber. The bellows plunger comprises a tubular body that includes a side wall having a shape defining at least one ridge extending continuously and helically about a longitudinal axis of the tubular body from a location proximate a first closed end of the body to a location proximate an opposite, second open end of the body.
In yet further embodiments, the present invention includes methods of forming bellows plungers in which a space between an outer surface of a mold core and an inner surface of a mold is filled with a molding material, and the molding material is solidified within the space to form a bellows plunger having a tubular body that includes a side wall having a shape defining at least one ridge extending continuously and helically about a longitudinal axis of the tubular body from a location proximate a first end of the tubular body to a location proximate a second end of the tubular body. The outer surface of the mold core may comprise at least one helically extending ridge, and the inner surface of the mold may comprise a helically extending recess complementary to and aligned with the helically extending ridge of the outer surface of the mold core to form the tubular body of the bellows plunger.
The illustrations presented herein may not be, in some instances, actual views of any particular reciprocating fluid pump, bellows plunger, mold assembly, or component thereof, but may be merely idealized representations that are employed to describe embodiments of the present invention. Additionally, elements common between figures may retain the same numerical designation.
The fluid pump 100 includes a pump body 102, which may comprise two or more components that may be assembled together to form the pump body 102. The pump body 102 may include therein a first cavity 110 and a second cavity 112. A drive shaft 116 may be positioned within the pump body 102 and extend between the first cavity 110 and the second cavity 112. A first end of the drive shaft 116 may be positioned within the first cavity 110, and an opposite second end of the drive shaft 116 may be positioned within the second cavity 112. The drive shaft 116 is configured to slide back and forth within pump body 102. Furthermore, a fluid-tight seal may be provided between a central portion of the drive shaft 116 and the pump body 102, such that fluid is prevented from flowing through any space between the drive shaft 116 and the pump body 102 between the first cavity 110 and the second cavity 112.
A first bellows plunger 120 may be disposed within the first cavity 110, and a second bellows plunger 122 may be disposed within the second cavity 112. The bellows plungers 120, 122 may each be formed of and comprise a flexible polymer material (e.g., an elastomer or a thermoplastic material). As discussed in further detail below, each of the bellows plungers 120, 122 may comprise one or more helically extending features (e.g., flutes) that enable the body of the bellows plungers 120, 122 to be longitudinally extended and compressed as the fluid pump 100 is cycled. The first bellows plunger 120 may divide the first cavity 110 into a first subject fluid chamber 126 on a side of the first bellows plunger 120 opposite the drive shaft 116 and a first drive fluid chamber 127 on a side of the first bellows plunger 120 proximate the drive shaft 116. Similarly, the second bellows plunger 122 may divide the second cavity 112 into a second subject fluid chamber 128 on a side of the second bellows plunger 122 opposite the drive shaft 116 and a second drive fluid chamber 129 on a side of the second bellows plunger 122 proximate the drive shaft 116.
A peripheral edge of the first bellows plunger 120 may be attached to the pump body 102, and a fluid tight seal may be provided between the pump body 102 and the first bellows plunger 120. The first end of the drive shaft 116 may, optionally, be coupled to the first bellows plunger 120. In some embodiments, the first end of the drive shaft 116 may extend through an aperture in the first bellows plunger 120, and sealing attachment members (e.g., nuts, washers, seals, etc.) may be provided on the drive shaft 116 on both sides of the first bellows plunger 120 to attach the first bellows plunger 120 to the first end of the drive shaft 116, and to provide a fluid tight seal between the drive shaft 116 and the first bellows plunger 120, such that fluid cannot flow between the first subject fluid chamber 126 and the first drive fluid chamber 127 through any space between the drive shaft 116 and the first bellows plunger 120.
Similarly, a peripheral edge of the second bellows plunger 122 may be attached to the pump body 102, and a fluid tight seal may be provided between the pump body 102 and the second bellows plunger 122. The second end of the drive shaft 116 may be coupled to the second bellows plunger 122. In some embodiments, the second end of the drive shaft 116 may extend through an aperture in the second bellows plunger 122, and sealing attachment members (e.g., nuts, washers, seals, etc.) may be provided on the drive shaft 116 on both sides of the second bellows plunger 122 to attach the second bellows plunger 122 to the second end of the drive shaft 116, and to provide a fluid tight seal between the drive shaft 116 and the second bellows plunger 122, such that fluid cannot flow between the second subject fluid chamber 128 and the second drive fluid chamber 129 through any space between the drive shaft 116 and the second bellows plunger 122.
In this configuration, the drive shaft 116 is capable of sliding back and forth within the pump body 102. As the drive shaft 116 moves to the right (from the perspective of
A first subject fluid inlet 130 may be provided in the pump body 102 that leads into the first subject fluid chamber 126 through the pump body 102, and a first subject fluid outlet 134 may be provided in the pump body 102 that leads out from the first subject fluid chamber 126 through the pump body 102. Similarly, a second subject fluid inlet 132 may be provided in the pump body 102 that leads into the second subject fluid chamber 128 through the pump body 102, and a second subject fluid outlet 136 may be provided in the pump body 102 that leads out from the second subject fluid chamber 128 through the pump body 102. Furthermore, a first subject fluid inlet check valve 131 may be provided proximate the first subject fluid inlet 130 to ensure that fluid is capable of flowing into the first subject fluid chamber 126 through the first subject fluid inlet 130, but incapable of flowing out from the first subject fluid chamber 126 through the first subject fluid inlet 130. A first subject fluid outlet check valve 135 may be provided proximate the first subject fluid outlet 134 to ensure that fluid is capable of flowing out from the first subject fluid chamber 126 through the first subject fluid outlet 134, but incapable of flowing into the first subject fluid chamber 126 through the first subject fluid outlet 134. Similarly, a second subject fluid inlet check valve 133 may be provided proximate the second subject fluid inlet 132 to ensure that fluid is capable of flowing into the second subject fluid chamber 128 through the second subject fluid inlet 132, but incapable of flowing out from the second subject fluid chamber 128 through the second subject fluid inlet 132. A second subject fluid outlet check valve 137 may be provided proximate the second subject fluid outlet 136 to ensure that fluid is capable of flowing out from the second subject fluid chamber 128 through the second subject fluid outlet 136, but incapable of flowing into the second subject fluid chamber 128 through the second subject fluid outlet 136.
Although not illustrated in the figures, the subject fluid inlets 130, 132 leading to the first subject fluid chamber 126 and the second subject fluid chamber 128 may be in fluid communication with a common fluid inlet line or conduit, and the subject fluid outlets 134, 136 leading out from the first subject fluid chamber 126 and the second subject fluid chamber 128 may be in fluid communication with a common fluid outlet line or conduit, such that fluid may be drawn into the pump through the fluid inlet line from a single fluid source, and fluid may be expelled from the pump through a single fluid outlet line.
The first drive fluid chamber 127 may be pressurized with pressurized drive fluid, which will push the first bellows plunger 120 to the left (from the perspective of
The second drive fluid chamber 129 may be pressurized with pressurized drive fluid, which will push the second bellows plunger 122 to the right (from the perspective of
Thus, to drive the pumping action of the fluid pump 100, the first drive fluid chamber 127 and the second drive fluid chamber 129 may be pressurized in an alternating manner to cause the drive shaft 116, the first bellows plunger 120, and the second bellows plunger 122 to reciprocate back and forth within the pump body 102, as discussed above.
The fluid pump 100 may comprise a shifting mechanism for shifting the flow of pressurized drive fluid back and forth between the first drive fluid chamber 127 and the second drive fluid chamber 129 at the ends of the stroke of the drive shaft 116. The shifting mechanism may comprise, for example, one or more shift pistons 140, 142 and a shuttle valve 170, as discussed in further detail below.
As shown in
A first shift-shuttle conduit 146A may extend between the first recess 143A, and the shuttle valve 170. A first shift piston vent conduit 148A may extend from the second recess 143B to the exterior of the pump body 102. Although an enlarged figure of the second shift piston 142 is not provided, a second shift-shuttle conduit 146B may extend between the second shift piston 142 and the shuttle valve 170 in a manner like that of the first shift-shuttle conduit 146A, and a second shift piston vent conduit 148B may extend from the second shift piston 142 to the exterior of the pump body 102 in a manner like that of the first shift piston vent conduit 148A, as shown in
With continued reference to
The shift piston 140 comprises an annular recess 156 in the outer surface of the shift piston 140. The annular recess 156 is located on the shift piston, and has a length (i.e., a dimension generally parallel to the longitudinal axis of the shift piston 140) that is sufficiently long, to cause the annular recess 156 to longitudinally overlap the second recess 143B throughout the stroke of the shift piston 140. In this configuration, fluid communication is provided between the space surrounding the shift piston 140 within the annular recess 156 and the exterior of the pump body 102 through the second recess 143B and the corresponding hole 152 in the cylindrical insert 150 that is aligned with the second recess 143B, which may facilitate movement of the shift piston 140 within the pump body 102.
As shown in
Referring again to
When the shift piston 140 is moving to the left (from the perspectives of
A drive fluid conduit 178 may lead to the middle, third recess 176C, as shown in
As can be seen by viewing
A first shuttle valve vent conduit 182A may extend from the first recess 176A to the exterior of the shuttle valve body 172, and a second shuttle valve vent conduit 182B may extend from the fifth recess 176E to the exterior of the shuttle valve body 172. These shuttle valve vent conduits 182A, 182B are illustrated in
The first shift-shuttle conduit 146A (previously described with reference to
As shown in
The shuttle spool 174 comprises a first annular recess 196A in the outer surface of the shuttle spool 174 and a second annular recess 196B in the outer surface of the shuttle spool 174. The first annular recess 196A and the second annular recess 196B are separated by a central annular ridge 197 on the outer surface of the shuttle spool 174. Furthermore, an annular first end ridge 198A is provided on the outer surface of the shuttle spool 174 on a longitudinal side of the first annular recess 196A opposite the central annular ridge 197, and an annular second end ridge 198B is provided on the outer surface of the shuttle spool 174 on a longitudinal side of the second annular recess 196B opposite the central annular ridge 197.
Each of the first annular recess 196A and the second annular recess 196B have a length (i.e., a dimension generally parallel to the longitudinal axis of the shuttle spool 174) that is long enough to at least partially longitudinally overlap two adjacent recesses of the five recesses 176A-176E. For example, when the shuttle spool 174 is in the position shown in
As can be seen by viewing
To facilitate a complete understanding of operation of the fluid pump 100, a complete pumping cycle of the fluid pump (including a leftward stroke and a rightward stroke of the drive shaft 116) is described below.
A cycle of the fluid pump 100 begins while the shuttle spool 174 of the shuttle valve 170 is in the position shown in
As this leftward stroke continues, the first shift piston 140 is urged to the left by the pressurized drive fluid within the space 162 (
Although the shuttle spool 174 is not illustrated in the drawing Figures as being positioned at the opposite end of the bore within the shuttle valve body 172, it will be appreciated that, when the shuttle spool 174 is moved to the opposite end of the bore within the shuttle valve body 172, the pressurized drive fluid entering the shuttle valve 170 through the drive fluid conduit 178 will be diverted from the first drive chamber conduit 180A to the second drive chamber conduit 180B. In other words, upon movement of the shuttle spool 174 to the opposite end of the shuttle valve body 172, pressurized drive fluid will pass from the drive fluid conduit 178, through the second annular recess 196B in the shuttle spool 174, and through the second drive chamber conduit 180B to the second drive fluid chamber 129 (
This rightward stoke continues until the second shift piston 140 moves sufficiently far to the right (from the perspectives of
As previously discussed, in accordance with some embodiments of the present invention, each of the bellows plungers 120, 122 may comprise one or more helically extending features (e.g., flutes) that enable the body of the bellows plungers 120, 122 to be longitudinally extended and compressed as the fluid pump 100 is cycled.
The body 200 of the bellows plunger 120 may be generally tubular. Referring to
In some embodiments, the peaks 208 may be defined by and comprise a single helically extending ridge 220, and the valleys 210 may be defined by and comprise a single helically extending recess 222. In such embodiments, as one peak 208 (and ridge 220) is followed once around the body 200 through one complete revolution of a full three hundred and sixty degrees, the peak 208 will lead to the next immediately adjacent peak 208 along the profile of the body 200.
In other embodiments, however, the peaks 208 may be defined by and comprise two (or more) helically extending ridges 220, and the valleys 210 may be defined by and comprise two (or more) helically extending recesses 222. Such multiple ridges 220 and multiple valleys 210 may extend helically alongside one another. In such embodiments, as one peak 208 (and ridge 220) is followed once around the body 200 through one complete revolution of a full three hundred and sixty degrees, the peak 208 will not lead to the next, immediately adjacent peak 208 (which will be part of a different ridge 220), but rather to second (or third, etc.) peak 208 therefrom.
In some embodiments, the body 200 may have a generally cylindrical shape with an at least substantially constant transverse, cross-sectional average diameter along the length thereof. The cross-sectional shape of the body 200 may be any shape capable of fitting within the first cavity 110 or the second cavity 112 in the pump body 102, and may be generally cylindrical, generally conical, generally rectangular in cross-sectional shape, etc.
Thus, the wall 206 of the body 200 of the bellows plunger 120 may include one or more substantially continuous, helical ridges 220 and helical recesses 222. The one or more substantially continuous, helical ridges 220 and helical recesses of the body 200, which define ribs or flutes of the bellows plunger 120, may extend from a location near the closed end 202 to a position near the open end 204. The helical ridges 220 and recesses 222 allow the body 200 of the bellows plunger 120 to compress and expand longitudinally. The one or more helically extending ridges 220 may, thus, be appropriately characterized as “ribs” of the bellows plunger 120, by enabling the body 200 to longitudinally expand and contract, even though the structure of the one or more helical ridges 220 provides one or more long, continuous ribs rather than a plurality of discrete, laterally extending and longitudinally separated ribs like those of previously known bellows plungers. Thus, expansion and contraction of the body 200 may be likened in operation to expansion and contraction of a coil spring.
The closed end 202 may comprise an end plate 230 coupled to, or integrally formed with the body 200. In other words, in some embodiments, the end plate 230 may be formed integrally with the body 200, and in other embodiments, the closed end 202 may be formed separate from the body 200 and attached to the end of the body 200. For example, an end plate 230 may be attached to the body 200 using an adhesive, a fastener (e.g., bolts and screws), heat sealing (e.g., melt bonding), or with some other known means, as well as combinations thereof. In at least some embodiments, the closed end 202 may comprise an annular flange 232, to which the one or more helical ridges 220 extend. In some embodiments, the end plate 230 may also include a recess 234 therein. The exterior of closed end 202 may comprise a shaped surface 236 configured to engage a complementarily shaped interior surface of the pump body 102. By way of example and not limitation, the shaped surface 236 may be at least substantially flat, frustoconical, convex or concave.
The shaped surface 236 may include a central protrusion 238 extending therefrom in some embodiments. In other embodiments, the shaped surface 236 may comprise an opening to permit attachment of the closed end 202 to the drive shaft 116 (
In some embodiments, the end plate 230 may include a structural insert 240 positioned therein. The structural insert may comprise a relatively rigid material compared to a material of the body 200 of the bellows plunger 120 (i.e., a material that is more rigid than the material of the body 200). By way of example and not limitation, the end plate 230 may comprise a structural insert 240 configured as a plate-like structure or a reinforcement structure of some other configuration (e.g., ribs, mesh, etc.) formed at least partially within the end plate 230. The structural insert 240 may comprise a metal or metal alloy, such as steel (including without limitation a stainless steel), a plastic, or a ceramic material. Those of ordinary skill in the art will recognize that such materials are only exemplary and that various other materials, or combinations of materials, may be used for structural insert 240. The structural insert 240 may further include one or more features, such as attachment means (e.g., threads) for accommodating attachment of an attachment structure (e.g., a bolt or screw). One or more structural inserts, such as a mesh, also may be provided in the walls of the body 200 of the bellows plunger 120.
The open end 204 of the body 200 of the bellows plunger 120 may comprise an annular flange 244 defining a central opening 246 to the interior 248 of bellows plunger 120. Annular flange 244 may be configured to accommodate securing the bellows plunger 120 to the pump body 102. By way of example and not limitation, the annular flange 244 may have a rectangular cross-sectional shape, taken longitudinally, and may be configured to be clamped, or otherwise secured to the pump body 102 or some other structure or device. Furthermore, in some embodiments, the annular flange 244 may comprise concentric ribs 245 on a flat longitudinal end face 250 of the flange 244 to improve a fluid-tight seal provided across the flange 244.
Referring again to
Furthermore, the position of the closed end 202 of each of the bellows plungers 120, 122 may be fixed relative to one another by the drive shaft 116 (
Although the first and second drive chamber conduits are used for both drive fluid input into the drive fluid chambers 127, 129 and exhausting of drive fluid out from the drive fluid chambers 127, 129, in additional embodiments, separate conduits may be used to input drive fluid into the drive fluid chambers 127, 129 and to exhaust drive fluid out from the drive fluid chambers 127, 129.
Additional embodiments of the invention include methods of making bellows plungers, such as the bellows plungers 120, 122 shown in the figures. The helical configuration of the one or more ridges 220 and recesses of the body 200 of the bellows plungers 120, 122 may improve the ease with which a bellows plunger according to embodiments of the invention may be manufactured.
In some embodiments, the mold 262 may comprise two or more components that may be assembled together to form the mold 262. An inner surface 270 of the mold 262 that defines the mold cavity therein may have a size, shape, and configuration at least substantially matching an outer surface 207B of the bellows plunger to be molded in the mold cavity (e.g., like the outer surface 207B of the bellows plunger 120 shown in
The mold core 264 may be sized, shaped, and configured to form an inner surface 207A of the bellows plunger 120. The inner surface 207A of the bellows plunger 120 may have a contour that is complementary to that of the outer surface 207B of the bellows plunger 120, and may include one or more helically extending ridges and recesses, as discussed hereinabove. Thus, an exterior surface 274 of the mold core 264 also may include one or more helically extending ridges and recesses.
When the mold core 264 is assembled with the mold 262, helically extending features on the inner surface 270 of the mold 262 may extend generally parallel to complementary, helically extending features on the exterior surface 274 of the mold core 264, forming a continuously extending cavity therebetween into which molding material may be injected. In some embodiments, the distance between the exterior surface 274 of the mold core 264 and the inner surface 270 of the mold 262 may be substantially uniform in regions that will be used to form the tubular wall 206 of the body 200 of the bellows plunger 120, such that the tubular wall 206 has a substantially uniform thickness along the one or more helically extending ridges 220 and recesses 222.
The mold core 264 may be positioned within the mold 262 with the helically extending features of the exterior surface 274 of the mold core 264 aligned with the complementary helically extending features of the inner surface 270 of the mold 262. The bellows plunger 120 may then be formed by filling the volume of space 268 that defines the mold cavity between the mold core 264 and the mold 262 with a suitable molding material. By way of example and not limitation, the molding material may be forced under pressure into the space 268 defining the mold cavity between the mold core 264 and the mold 262 using a conventional injection molding technique. Suitable molding materials include, but are not limited to, polymeric materials such as moldable elastomers and plastics. In some embodiments, the molding material may comprise a fluoropolymer. By way of example and not limitation, the molding material may comprise one or more of neoprene, buna-N, ethylene diene M-class (EPDM), VITON®, polyurethane, HYTREL®, SANTOPRENE®, fluorinated ethylene-propylene (FEP), perfluoroalkoxy fluorocarbon resin (PFA), ethylene-chlorotrifluoroethylene copolymer (ECTFE), ethylene-tetrafluoroethylene copolymer (ETFE), nylon, polyethylene, polyvinylidene fluoride (PVDF), NORDEL™, and nitrile.
The molding material that fills the space 268 may be cured or solidified in place in the mold assembly 260 to form a bellows plunger 120 therein. The newly formed bellows plunger 120 may be extracted from the mold assembly 260 by removing the mold 262 from around the molded bellows plunger 120 and removing the mold core 264 from within the bellows plunger 120. To remove the bellows plunger 120 from the mold 262, the mold 262 may be opened or disassembled from around the bellows plunger 120. In other embodiments, the bellows plunger 120 may be removed by unscrewing, or backing off, the bellows plunger 120 from within the mold 262. In other words, the bellows plunger 120 may be rotated relative to the mold 262 about the longitudinal axis of the bellows plunger 120. Upon such rotation, the helically extending features of the bellows plunger 120 may cause the bellows plunger 120 to move out from the mold 262.
The mold core 264 may be removed from the bellows plunger 120 by unscrewing it from within the bellows plunger 120 formed thereabout. In other words, the bellows plunger 120 may be rotated relative to the mold core 264 about the longitudinal axis of the bellows plunger 120. Upon such rotation, the helically extending features of the bellows plunger 120 may cause the bellows plunger 120 to move off from the mold core 264. Generally, the helically extending features of the bellows plunger 120 allow the bellows plunger 120 to be easily removed from the mold core 264 by backing it off longitudinally from the mold core 264 by providing relative rotation between the bellows plunger 120 and the mold core 264.
Previously known configurations of bellows plungers do not include such helically extending features, and, thus, are not molded within a mold 262 about a mold core 264, as in some embodiments of the present invention, as described herein. The ability to unscrew the mold core 264 from the bellows plunger 120 molded thereabout alleviates the problem of mechanical interference between the ribs of the bellows plunger 120 and the ribs of the mold core 264, such as would be experienced during the fabrication of previously known bellows plungers having a plurality of discrete, circumferentially extending ribs. Thus, a suitably contoured, one piece mold core 264 may be employed in forming the internal features on the bellows plunger 120.
Referring again to
Referring to
Referring to
Referring to
Although the fluid pump 100 of
Furthermore, embodiments of bellows plungers as described hereinabove may be used in all reciprocating or oscillating fluid handling devices, including, but not limited to, pumps, valves, and pulsation dampeners.
Thus, while certain embodiments have been described and shown in the accompanying drawings, such embodiments are merely illustrative and not restrictive of the scope of the invention, and this invention is not limited to the specific constructions and arrangements shown and described, since various other additions and modifications to, and deletions from, the described embodiments will be apparent to one of ordinary skill in the art. The scope of the invention, therefore, is only limited by the literal language, and legal equivalents, of the claims which follow.
This application is a continuation-in-part of, and claims priority to, co-pending U.S. patent application Ser. No. 12/351,516, which was filed Jan. 9, 2009 and entitled “Helical Bellows, Pump Including Same and Method of Bellows Fabrication,” the disclosure of which is incorporated herein in its entirety by this reference.
Number | Date | Country | |
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Parent | 12351516 | Jan 2009 | US |
Child | 12684528 | US |