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Title:
PUMP WITH FLOATING CYLINDERS
Document Type and Number:
WIPO Patent Application WO/2019/148004
Kind Code:
A1
Abstract:
A pump includes a housing assembly having a frame with a support floor, a motor supported by the frame within the housing assembly, and a head assembly coupled to the housing assembly and including a plate. The pump also includes a first sleeve extending between the support floor and the plate, a second sleeve extending between the support floor and the plate, a first piston configured to be driven by the motor to reciprocate within the first sleeve, and a second piston configured to be driven by the motor to reciprocate within the second sleeve.

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Inventors:
SUPPIGER, Robert, Joseph (2108 Willow Pond Way, Grafton, WI, 53024, US)
Application Number:
US2019/015246
Publication Date:
August 01, 2019
Filing Date:
January 25, 2019
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
GARDNER DENVER THOMAS, INC. (1419 Illinois Avenue, Sheboygan, WI, 53081, US)
International Classes:
F04B39/12; F04B39/14; F04B43/02; F04B53/00; F04B53/16
Foreign References:
US20010009646A12001-07-26
US20150147202A12015-05-28
US20060275160A12006-12-07
US6443713B12002-09-03
US20100158708A12010-06-24
Attorney, Agent or Firm:
MUTH, Jason, P. (Michael Best & Friedrich LLP, 100 E. Wisconsin Avenue Suite 330, Milwaukee WI, 53202, US)
Download PDF:
Claims:
CLAIMS

What is claimed is:

1. A pump comprising:

a housing assembly including a frame with a support floor;

a motor supported by the frame within the housing assembly;

a head assembly coupled to the housing assembly and including a plate;

a first sleeve extending between the support floor and the plate;

a second sleeve extending between the support floor and the plate;

a first piston configured to be driven by the motor to reciprocate within the first sleeve; and

a second piston configured to be driven by the motor to reciprocate within the second sleeve.

2. The pump of claim 1, further comprising a plurality of fasteners coupling the head assembly to the housing assembly, wherein the first sleeve and the second sleeve are movable along the support floor when the plurality of fasteners is in a loosened state, and wherein the first sleeve and the second sleeve are clamped between the support floor and the plate to inhibit movement of the first and second sleeves when the plurality of fasteners is in a tightened state.

3. The pump of claim 2, wherein the motor includes a shaft defining a rotational axis, and wherein the pump further comprises an alignment element configured to inhibit movement of the first sleeve in a direction perpendicular to the rotational axis.

4. The pump of claim 1, further comprising a diaphragm spanning across an end of the first sleeve, wherein the first piston is coupled to the diaphragm such that the diaphragm is configured to flex in response to reciprocation of the first piston.

5. The pump of claim 1, wherein one or both of the first sleeve and the second sleeve has a non-circular cross-sectional shape.

6. The pump of claim 1, wherein the first sleeve and the second sleeve have different geometries.

7. The pump of claim 1, wherein the plate includes a first inlet aperture and a first outlet aperture in fluid communication with an interior of the first sleeve.

8. The pump of claim 7, wherein the plate includes a second inlet aperture and a second outlet aperture in fluid communication with an interior of the second sleeve.

9. The pump of claim 8, further comprising:

a first inlet valve coupled to the plate, the first inlet valve configured to permit fluid flow through the first inlet aperture in response to movement of the first piston away from the plate and to inhibit fluid flow through the first inlet aperture in response to movement of the first piston toward the plate; and

a first outlet valve coupled to the plate, the first outlet valve configured to permit fluid flow through the first outlet aperture in response to movement of the first piston toward the plate and to inhibit fluid flow through the first outlet aperture in response to movement of the first piston away from the plate.

10. The pump of claim 9, further comprising:

a second inlet valve coupled to the plate, the second inlet valve configured to permit fluid flow through the second inlet aperture in response to movement of the second piston away from the plate and to inhibit fluid flow through the second inlet aperture in response to movement of the second piston toward the plate; and

a second outlet valve coupled to the plate, the second outlet valve configured to permit fluid flow through the second outlet aperture in response to movement of the second piston toward the plate and to inhibit fluid flow through the second outlet aperture in response to movement of the second piston away from the plate.

11. The pump of claim 8, wherein the head assembly includes a head cover coupled to the plate, the head cover including an intake passage in fluid communication with the first inlet aperture and the second inlet aperture, an exhaust passage in fluid communication with the first outlet aperture and the second outlet aperture, and a wall separating the intake passage from the exhaust passage.

12. A pump comprising:

a housing assembly including a frame;

a head assembly including a plate;

a first sleeve extending between the frame and the plate;

a second sleeve extending between the frame and the plate;

a first piston configured to reciprocate within the first sleeve;

a second piston configured to reciprocate within the second sleeve; and

a plurality of fasteners coupling the head assembly to the housing assembly, wherein the first sleeve and the second sleeve are movable along the frame in a loosened state of the plurality of fasteners, and

wherein the first sleeve and the second sleeve are clamped between the frame and the plate to inhibit movement of the first sleeve and the second sleeve in a tightened state of the plurality of fasteners.

13. The pump of claim 12, further comprising:

a first rod coupled to the first piston; and

a second rod coupled to the second piston,

wherein the first rod and the second rod are pivotable about an axis.

14. The pump of claim 13, further comprising an alignment element configured to inhibit movement of the first sleeve in a direction perpendicular to the axis.

15. The pump of claim 12, wherein the plate include a first inlet aperture and a first outlet aperture in fluid communication with an interior of the first sleeve, and wherein the plate includes a second inlet aperture and a second outlet aperture in fluid communication with an interior of the second sleeve.

16. The pump of claim 15, wherein the head assembly includes a head cover coupled to the plate, the head cover including an intake passage in fluid communication with the first inlet aperture and the second inlet aperture, an exhaust passage in fluid communication with the first outlet aperture and the second outlet aperture, and a wall separating the intake passage from the exhaust passage.

17. A method of assembling a pump, the method comprising:

positioning a first sleeve and a second sleeve on a support floor of a frame;

aligning the first sleeve with a first piston configured to reciprocate within the first sleeve;

aligning the second sleeve with a second piston configured to reciprocate within the second sleeve;

positioning a head assembly over the first sleeve and the second sleeve;

tightening a plurality of fasteners to clamp the first sleeve and the second sleeve between the support floor and a bottom surface of the head assembly that opposes the support floor.

18. The method of claim 17, wherein prior to tightening the plurality of fasteners, the first sleeve and the second sleeve are movable along support floor.

19. The method of claim 17, wherein the pump includes a motor having a shaft configured to rotate about an axis, and wherein prior to tightening the plurality of fasteners, the first sleeve and the second sleeve are movable along the support floor in a direction parallel to the axis and inhibited from moving along the support floor in a direction perpendicular to the axis.

20. The method of claim 17, wherein tightening the plurality of fasteners creates a seal between the bottom surface of the head assembly and each of the first and second sleeves.

21. The method of claim 17, wherein the first sleeve has a different geometry than the second sleeve.

22. The method of claim 21, wherein the first sleeve has a greater volume than the second sleeve.

23. The method of claim 17, wherein the first piston has a different geometry than the second piston.

Description:
PUMP WITH FLOATING CYLINDERS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to co-pending U.S. Provisional Patent Application No. 62/622,338, filed on January 26, 2018, the entire content of which is incorporated herein by reference.

FIELD

[0002] The present disclosure relates to compressors and pumps.

BACKGROUND

[0003] Reciprocating compressors and pumps typically have at least one piston and cylinder that must be precisely aligned to minimize wear. Such precise alignment typically requires tight tolerances and associated increases in manufacturing cost and complexity.

SUMMARY

[0004] The disclosure provides, in one aspect, a pump including a housing assembly having a frame with a support floor, a motor supported by the frame within the housing assembly, and a head assembly coupled to the housing assembly and including a plate. The pump also includes a first sleeve extending between the support floor and the plate, a second sleeve extending between the support floor and the plate, a first piston configured to be driven by the motor to reciprocate within the first sleeve, and a second piston configured to be driven by the motor to reciprocate within the second sleeve.

[0005] In some embodiments, the pump includes a plurality of fasteners coupling the head assembly to the housing assembly. The first sleeve and the second sleeve are movable along the support floor when the plurality of fasteners is in a loosened state, and the first sleeve and the second sleeve are clamped between the support floor and the plate to inhibit movement of the first and second sleeves when the plurality of fasteners is in a tightened state. [0006] In some embodiments, the motor includes a shaft defining a rotational axis, and the pump further includes an alignment element configured to inhibit movement of one or both of the first sleeve and the second sleeve in a direction perpendicular to the rotational axis.

[0007] In some embodiments, the pump includes a diaphragm spanning across an end of the first sleeve. The first piston is coupled to the diaphragm such that the diaphragm is configured to flex in response to reciprocation of the first piston.

[0008] In some embodiments, one or both of the first sleeve and the second sleeve has a non circular cross-sectional shape.

[0009] In some embodiments, one or both of the first sleeve and the second sleeve has a circular cross-sectional shape.

[0010] In some embodiments, the first sleeve and the second sleeve have different geometries.

[0011] In some embodiments, the plate includes a first inlet aperture and a first outlet aperture in fluid communication with an interior of the first sleeve.

[0012] In some embodiments, the plate includes a second inlet aperture and a second outlet aperture in fluid communication with an interior of the second sleeve.

[0013] In some embodiments, the pump includes a first inlet valve coupled to the plate to permit fluid flow through the first inlet aperture in response to movement of the first piston away from the plate and to inhibit fluid flow through the first inlet aperture in response to movement of the first piston toward the plate. The pump also includes a first outlet valve coupled to the plate to permit fluid flow through the first outlet aperture in response to movement of the first piston toward the plate and to inhibit fluid flow through the first outlet aperture in response to movement of the first piston away from the plate.

[0014] In some embodiments, the pump includes a second inlet valve coupled to the plate to permit fluid flow through the second inlet aperture in response to movement of the second piston away from the plate and to inhibit fluid flow through the second inlet aperture in response to movement of the second piston toward the plate. The pump also includes a second outlet valve coupled the plate to permit fluid flow through the second outlet aperture in response to movement of the second piston toward the plate and to inhibit fluid flow through the second outlet aperture in response to movement of the second piston away from the plate.

[0015] In some embodiments, the head assembly includes a head cover coupled to the plate, the head cover including an intake passage in fluid communication with the first inlet aperture and the second inlet aperture, an exhaust passage in fluid communication with the first outlet aperture and the second outlet aperture, and a wall separating the intake passage from the exhaust passage.

[0016] The disclosure provides, in another aspect, a pump including a housing assembly with a frame, a head assembly with a plate, a first sleeve extending between the frame and the plate, and a second sleeve extending between the frame and the plate. The pump also includes a first piston configured to reciprocate within the first sleeve, a second piston configured to reciprocate within the second sleeve, and a plurality of fasteners coupling the head assembly to the housing assembly. The first sleeve and the second sleeve are movable along the frame in a loosened state of the plurality of fasteners, and the first sleeve and the second sleeve are clamped between the frame and the plate to inhibit movement of the first sleeve and the second sleeve in a tightened state of the plurality of fasteners.

[0017] In some embodiments, the pump includes a first rod coupled to the first piston and a second rod coupled to the second piston. The first rod and the second rod are pivotable about an axis.

[0018] In some embodiments, the pump includes an alignment element configured to inhibit movement of one or both of the first sleeve and the second sleeve in a direction perpendicular to the axis.

[0019] In some embodiments, the plate include a first inlet aperture and a first outlet aperture in fluid communication with an interior of the first sleeve, and the plate includes a second inlet aperture and a second outlet aperture in fluid communication with an interior of the second sleeve. [0020] In some embodiments, the head assembly includes a head cover coupled to the plate, the head cover including an intake passage in fluid communication with the first inlet aperture and the second inlet aperture, an exhaust passage in fluid communication with the first outlet aperture and the second outlet aperture, and a wall separating the intake passage from the exhaust passage.

[0021] The disclosure provides, in another aspect, a method of assembling a pump, including positioning a first sleeve and a second sleeve on a support floor of a frame, aligning the first sleeve with a first piston configured to reciprocate within the first sleeve, aligning the second sleeve with a second piston configured to reciprocate within the second sleeve, positioning a head assembly over the first sleeve and the second sleeve, and tightening a plurality of fasteners to clamp the first sleeve and the second sleeve between the support floor and a bottom surface of the head assembly that opposes the support floor.

[0022] In some embodiments, prior to tightening the plurality of fasteners, the first sleeve and the second sleeve are movable along support floor.

[0023] In some embodiments, the pump includes a motor having a shaft configured to rotate about an axis, and prior to tightening the plurality of fasteners, the first sleeve and the second sleeve are movable along the support floor in a direction parallel to the axis and inhibited from moving along the support floor in a direction perpendicular to the axis.

[0024] In some embodiments, tightening the plurality of fasteners creates a seal between the bottom surface of the head assembly and each of the first and second sleeves.

[0025] In some embodiments, the first sleeve has a different geometry than the second sleeve.

[0026] In some embodiments, the first sleeve has a greater volume than the second sleeve.

[0027] In some embodiments, the first piston has a different geometry than the second piston. [0028] Other features and aspects of the disclosure will become apparent by consideration of the following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. l is a perspective view of a pump according to an embodiment of the disclosure.

[0030] FIG. 2 is a cross-sectional view of the pump of FIG. 1 taken along line 2— 2.

[0031] FIG. 3 is a partially exploded view of the pump of FIG. 1.

[0032] FIG. 4 is a top view of end housings and sleeves of the pump of FIG. 1.

[0033] FIG. 5 is an exploded view of a head assembly of the pump of FIG. 1.

[0034] FIG. 6 is a bottom view of a valve plate of the head assembly of FIG. 5.

[0035] Before any embodiments of the disclosure are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The disclosure is capable of supporting other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the

phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

DETAILED DESCRIPTION

[0036] FIG. 1 illustrates a multi-cylinder air compressor or pump 10 including a housing assembly 14, a head assembly 18, and first and second cylinders 20, 22 extending between the housing assembly 14 and the head assembly 18. The illustrated housing assembly 14 includes two end frames 26 and two end caps 30 coupled to the respective end frames 26. The head assembly 18 includes a valve plate 50 and a head manifold or head cover 54. In some embodiments, the head assembly 18 may further include a pair of pressure swing absorption oxygen concentrators (not shown) for separating oxygen and nitrogen from compressed air. [0037] Referring to FIG. 2, the pump 10 further includes a prime mover, which is an electric motor 62 in the illustrated embodiment. The motor 62 has a rotor or drive shaft 66 encircled by a motor housing 70. In the illustrated embodiment, the motor 62 is generally centered between the cylinders 20, 22. The drive shaft 66 is rotatable about an axis 74 and is supported by a pair of bearings 78 (e.g., ball bearings) fixed within bearing seats 82 formed by the end frames 26. Each of the end frames 26 includes a plurality of openings or windows 86 that allow air to circulate around the motor 62 (FIG. 1). The motor housing 70 includes a central circumferential flange 90 having reliefs 94 that receive opposing ends 98 of the end frames 26 to join the end frames 26 to the motor housing 70 (FIG. 2). In the illustrated embodiment, fasteners 102 (e.g., bolts) extend between the end frames 26 in a direction parallel to the axis 74 and clamp the motor housing 70 between the end frames 26 (FIG. 1). In other embodiments, the end frames 26 and the motor housing 70 may be integrally formed together as a single piece or may be joined in other ways (e.g., via welding, brazing, etc.).

[0038] With reference to FIG. 3, each of the end frames 26 includes a cylinder extension 106 associated with one of the respective cylinders 20, 22 of the pump 10. Each cylinder extension 106 presents a planar support floor 110. The illustrated support floors 110 are generally C- shaped, and each includes a central opening 114. In other embodiments, the support floors 110 may have different shapes (e.g., annular, elliptical, etc.). Sidewalls of the cylinder extensions 106 are provided with bosses 122 that receive fasteners 126 (e.g., bolts) to couple the head assembly 18 to the end frames 26.

[0039] With reference to FIGS. 3 and 4, the pump 10 further includes first and second sleeves 130, 134. Each of the sleeves 130, 134 includes a top end 135, a bottom end 136, and a bore 137 that extends through the top and bottom ends 135, 136. The sleeves 130, 134 are supported on the respective support floors 110, with their bottom ends 136 in abutting contact with the support floors 110. The sleeves 130, 134 may have a variety of cross-sectional shapes such that the sleeves 130, 134 may or may not be cylindrical. For example, in the illustrated embodiment, the first sleeve 130 has an elliptical or elongated cross-sectional shape, and the second sleeve 134 has a circular cross-sectional shape. [0040] The support floors 110 each define a maximum diameter Dl, and each of the sleeves 130, 134 defines a maximum outer diameter D2, D3 (FIG. 4). The support floors 110 and sleeves 130, 134 may not be round in some embodiments. Accordingly, it should be understood that the maximum diameter Dl of each support floor 110 is the maximum linear distance between outermost points of the support floor 110 that passes through the center of the support floor 110, and likewise the maximum diameter D2, D3 of each sleeve 130, 134 is the maximum linear distance between outermost points of the sleeve 130, 134 that passes through the center of the sleeve 130, 134. In some embodiments, the maximum diameter D2, D3 of each sleeve 130, 134 is less than or equal to the maximum diameter Dl of the support floors 110. Alternatively, if the sleeves 130, 134 have an elongated shape, the maximum diameter D2, D3 of each sleeve 130, 134 may also be greater than the maximum diameter Dl of the support floors 110. In such embodiments, a portion of the bottom end 136 of each sleeve 130, 134 may extend beyond (i.e. overhang) the outer extent of the support floors 110.

[0041] Referring to FIG. 2, a first piston 138 is associated with the first cylinder 20, and a second piston 142 is associated with the second cylinder 22. A rod 146 extends from each piston 138, 142. The rods 146 are mounted on bearings 150, which are supported by eccentrics 154.

The eccentrics 154 are mounted adjacent opposite distal ends 158 of the drive shaft 66. In the illustrated embodiment, each eccentric 154 includes a counterweight 162 for balance.

[0042] The pistons 138, 142 are reciprocable within the bores 137 of the respective sleeves 130, 134, with the rods 146 extending through the openings 114 in the support floors 110. In the illustrated embodiment, the first piston 138 is coupled to a flexible diaphragm 166 that spans the top end 135 of the first sleeve 130 and oscillates in response to reciprocation of the first piston 138. The second piston 142 includes a peripheral seal 170 that engages and seals against an inner wall 174 of the second sleeve 134. Either or both of the pistons 138, 142 may reciprocate linearly or may be configured as WOB-L pistons that tilt within the sleeves 130, 134 as they reciprocate.

[0043] The sleeves 130, 134 may be identical for a particular pump 10 but differ in the illustrated embodiment to show that a variety of differently sized and shaped sleeves 130, 134 can be accommodated on the support floors 110 without requiring any modification of the housing assembly 14 or the head assembly 18. Likewise, the pistons 138, 142 may be identical but differ in the illustrated embodiment to show that the pump 10 can include a variety of different piston configurations without requiring any modification of the housing assembly 14 or the head assembly 18. The housing assembly 14 and head assembly 18 of the pump 10 also allow the pump 10 to be assembled with sleeves 130, 134 and pistons 138, 142 of differing geometries (e.g., diameters, shapes, volumes, etc.). For example, in some embodiments, the sleeve 134 may have a smaller volume and greater wall thickness than the sleeve 130. Such a configuration may be particularly advantageous if the pump 10 is a two-stage pump, with the first cylinder 20 configured to compress air or other fluid for discharge into the second cylinder 22, which further compresses the air or other fluid.

[0044] With reference to FIGS. 3, 5, and 6, the valve plate 50 includes a first cylinder portion 178 that overlies the first cylinder 20, a second cylinder portion 182 that overlies the second cylinder 22, and a middle portion 186 that spans between the cylinder portions 178, 182. A top surface 190 (FIG. 5) and a bottom surface 194 (FIG. 6) of the valve plate 50 extend across the first and second cylinder portions 178, 182 and the middle portion 186. The head cover 54 includes a first portion 198 that overlies the first cylinder portion 178 of the valve plate 50, a second portion 202 that overlies the second cylinder portion 182 of the valve plate 50, and a middle portion 206 the spans between the two portions 198, 202 (FIG. 5).

[0045] The head cover 54 includes an outer wall 210 extending around the perimeter of the head cover 54 and a center wall 214 within the perimeter of the outer wall 210 and bisecting the first portion 198, the middle portion 206, and the second portion 202 to form an intake channel 218 and an exhaust channel 222. Accordingly, the intake channel 218 and the exhaust channel 222 are on opposite sides of the center wall 214. A plurality of intake ports 226 communicates with the intake channel 218, and a plurality of exhaust ports 230 communicates with the exhaust channel 222. The intake ports 226 may communicate with the environment to allow ambient air to be drawn into the intake channel 218, or the intake ports 226 may communicate with another system or reservoir. Likewise the exhaust ports 230 may communicate with the environment or may communicate with another system or reservoir. [0046] In the illustrated embodiment, the outer wall 210 of the head cover 54 defines an outer groove 234, and the center wall 214 defines an inner groove 238 that connects to and bisects the outer groove 234. The grooves 234, 238 support a circuitous gasket 242 made of rubber or another suitable sealing material. The gasket 242 seals against the top surface 190 of the valve plate 50 to define an intake section 246 and an exhaust section 250. The intake section 246 of the valve plate 50 includes an inlet aperture 254 defined in and extending through each of the first and second cylinder portions 178, 182 corresponding to each of the cylinders 20, 22. Each of the inlet apertures 254 has a corresponding inlet flapper valve 258 to allow intake air to enter but not exit the cylinder bores 137 through the inlet apertures 254. The exhaust section 250 of the valve plate 50 includes an outlet aperture 262 defined in and extending through each of the first and second cylinder portions 178, 182 corresponding to each of the cylinders 20, 22. Each of the outlet apertures 262 has a corresponding outlet flapper valve 266 to allow exhaust air to exit but not enter the cylinder bores 137 through the outlet apertures 262. In other embodiments, other types of one-way valves may be used.

[0047] The bottom surface 194 of the valve plate 50 is recessed relative to an outer wall 270 that forms a perimeter of the valve plate 50 (FIG. 6). The bottom surface 194 is planar and engages the top ends 135 of the sleeves 130, 134 (FIG. 2). More specifically, the bottom surface 194 abuts the top end 135 of the first sleeve 130 in the first cylinder portion 178 and abuts the top end 135 of the second sleeve 134 in the second cylinder portion 182. In the illustrated embodiment, an o-ring 274 is provided in a groove 278 formed in the top end 135 of the second sleeve 134, and an outer periphery of the diaphragm 166 overlays at least a portion of the top end 135 of the first sleeve 130. The diaphragm 166 and the o-ring 274 provide air-tight seals between the respective sleeves 130, 134 and the bottom surface 194 of the valve plate 50. The sleeves 130, 134 may have identical sealing arrangements, but they differ in the illustrated embodiment to show that the sleeves 130, 134 can be sealed against the bottom surface 194 of the valve plate 50 in a variety of ways, without requiring any modification of the valve plate 50.

[0048] Referring to FIG. 3, the fasteners 126 extend through bosses 286 disposed about the perimeter of the head cover 54 and through corresponding bosses 290 disposed about the perimeter of the valve plate 50. The distal ends of the fasteners 126 are threaded into the bosses 122 of the end housings 26 to secure the head assembly 18 to the housing assembly 14 and thereby clamp the sleeves 130, 134 between the support floors 110 and the bottom surface 194 of the valve plate 50. In the illustrated embodiment, both the head cover 54 and the valve plate 50 are unitary structural members that span across and interconnect the cylinders 20, 22. In other embodiments, one of the head cover 54 and the valve plate 50 may include a plurality of separate segments (e.g., two segments) coupled to the other of the head cover 54 and the valve plate 50. For example, in one embodiment, the head assembly 18 may include independent valve plates associated with each of the cylinders 20, 22 and a unitary head cover that spans across and interconnects the valve plates and the cylinders 20, 22. In an alternative embodiment, the head assembly 18 may include independent head covers associated with each of the cylinders 20, 22 and a unitary valve plate that spans across and interconnects the head covers and the cylinders 20, 22.

[0049] During assembly of the pump 10, the sleeves 130, 134 are set upon the support floors 110 of the cylinder extensions 106 and aligned with the respective pistons 138, 142. (FIG. 3). The head assembly 18 is then set upon the sleeves 130, 134, and the fasteners 126 are tightened to clamp the sleeves 130, 134 between the support floors 110 and the bottom surface 194 of the valve plate 50 (FIG. 2). At least one of the head cover 54 and the valve plate 50 spans continuously across both cylinders 20, 24 to provide structural support for the top ends 135 of the sleeves 130, 134.

[0050] The sleeves 130, 134 are able to“float” during assembly. In other words, because the sleeves 130, 134 are secured between two parallel planar surfaces 110, 194, they can be moved in any direction (to an extent permitted by the maximum diameters D2, D3 of the sleeves 130,

134 and the maximum diameter Dl of the support floors 110) before the fasteners 126 are tightened. This allows the sleeves 130, 134 to be easily and precisely aligned with the pistons 138, 142 during assembly, which advantageously negates the impact of tolerance stacking that may occur with conventional multi-cylinder pumps or compressors. Accordingly, tolerances for the housing assembly 14, the pistons 138, 142, and other associated components of the pump 10 may be relaxed without adversely affecting the alignment of the pistons 138, 142 with the sleeves 130, 134. [0051] In addition, a variety of differently sized and shaped sleeves 130, 134 may be used interchangeably, without modifying the housing assembly 14 or the head assembly 18. This allows many variants of the pump 10 to be produced with a minimal amount of additional tooling. For example, the same housing assembly 14 and head assembly 18 could be used to assemble the pump 10 as a diaphragm pump with elliptical sleeves (e.g., 130) or as a WOB-L piston pump with cylindrical sleeves (e.g., 134). In addition, the same housing assembly 14 and head assembly 18 could be used to assemble the pump 10 as a low pressure/high volume pump with relatively large diameter sleeves or as a high pressure/low volume pump with relatively small diameter sleeves.

[0052] In some embodiments, one or more alignment elements 293 (FIG. 4) constrain lateral movement of one or both of the sleeves 130, 134 in at least one direction. In FIG. 4, exemplary alignment elements 293 are illustrated on only one of the support floors 110; however, alignment elements 293 may be provided on both of the support floors 110, on the bottom surface 194 of the valve plate 50, or both. The alignment elements 293 may include, for example, one or more grooves, walls, posts, or the like.

[0053] The sleeve(s) 130, 134 are movable along the associated alignment elements 293 in a direction parallel to the axis 74 of the drive shaft 66, but the alignment elements 293 prevent movement of the associated sleeve(s) 130, 134 in a direction perpendicular to the axis 74 (i.e. normal to the viewing plane of FIG. 2). The alignment elements 293 thus facilitate assembly of the pump 10 in some embodiments because the pistons 138, 142 and rods 146 tend to tilt under the influence of gravity, in directions perpendicular to the axis 74. The alignment features 293 advantageously center the sleeve(s) 130, 134 in this direction, while permitting adjustment of the sleeves 130, 134 parallel to the axis 74.

[0054] In operation, the motor 62 rotationally drives the drive shaft 66, causing the pistons 138, 142 to reciprocate within the bores 137 of each of the sleeves 130, 134. During a downstroke of each of the pistons 138, 142, air is drawn in through the intake ports 226 and alternatively drawn into the cylinders 20, 22 through the corresponding inlet apertures 254. The flapper valves 258 allow intake air to enter but not exit the bores 137 through the inlet apertures 254. The air is thereafter compressed by the upstroke of the pistons 138, 142 and forced out the respective outlet apertures 262 through the outlet flapper valves 266 at an increased pressure.

The outlet flapper valves 266 prevent the compressed air from reentering the bores 137. The compressed air leaves the outlet aperture 262 of each of the first and second cylinders 20, 22 and enters the exhaust channel 222. The compressed air may then be discharged through the exhaust ports 230. In some embodiments, the pump 10 can be configured as a two-stage pump. In such embodiments, the head assembly 18 routes compressed air discharged from one of the cylinders 20, 22 into the intake of the other one of the cylinders 20, 22 to further compress the air.

[0055] Although the pump 10 illustrated and described herein is a two-cylinder pump, in alternate embodiments the pump 10 may include any number of cylinders. In addition, one of ordinary skill in the art would recognize that the disclosure also equally applies to pumps and other similar devices that include cylinders and head assemblies.

[0056] Various features of the disclosure are set forth in the following claims.