Compressor and valve assembly

Abstract

A compressor may include a scroll and a discharge valve assembly. The scroll may include an end plate and a spiral wrap extending from the end plate. The end plate may include a discharge passage. The discharge valve assembly may be mounted to the scroll and may be configured to control fluid flow through the discharge passage within the discharge passage. The discharge valve assembly may include a base and a valve member. The base may be fixed relative to the end and may include a discharge opening in communication with the discharge passage. The valve member may be mounted to the base. The valve member may be deflectable relative to the base between a closed position and an open position. The discharge opening may include at least one radially extending lobe.

Claims

1. A compressor comprising: a scroll including an end plate and a spiral wrap extending from the end plate, the end plate including a discharge passage; and a discharge valve assembly mounted to the scroll and configured to control fluid flow through the discharge passage, the discharge valve assembly including a base and a valve member, wherein the base is fixed relative to the end plate and includes a discharge opening in communication with the discharge passage, wherein the valve member is mounted to the base, wherein the valve member is deflectable relative to the base between a closed position in which the valve member restricts fluid flow through the discharge opening and an open position in which the valve member allows fluid flow through the discharge opening, and wherein the discharge opening includes at least one radially extending lobe.

2. The compressor of claim 1, wherein the discharge valve assembly includes a backer fixed relative to the base, wherein the valve member is disposed between the backer and the base, and wherein the backer defines a range of motion of the valve member.

3. The compressor of claim 2, wherein the backer is configured to allow a maximum deflection of a distal tip of a movable end of the valve member of about 6.7 millimeters to about 13.5 millimeters.

4. The compressor of claim 1, wherein the discharge opening of the base includes four radially extending lobes.

5. The compressor of claim 4, wherein the four radially extending lobes are evenly spaced around a circle defined by radially inner portions of a surface that defines a periphery of the discharge opening.

6. The compressor of claim 1, wherein the scroll is a non-orbiting scroll.

7. The compressor of claim 1, wherein the discharge valve assembly includes a spacer disposed between the base and the valve member.

8. The compressor of claim 1, wherein a first side of the base includes a first seat surface and a second seat surface that is recessed from the first seat surface.

9. The compressor of claim 8, wherein the discharge opening extends through the first and second seat surfaces.

10. The compressor of claim 9, wherein a movable end of the valve member contacts the first seat surface when the valve member is in the closed position and is spaced apart from the first seat surface when the valve member is in the open position.

11. The compressor of claim 10, wherein the movable end of the valve member contacts the second seat surface when the valve member is in the closed position and is spaced apart from the second seat surface when the valve member is in the open position.

12. A compressor comprising: a scroll including an end plate and a spiral wrap extending from the end plate, the end plate including a discharge passage; and a discharge valve assembly mounted to the scroll and configured to control fluid flow through the discharge passage, the discharge valve assembly including a base and a valve member, wherein the base is fixed relative to the end plate and includes a discharge opening in communication with the discharge passage, wherein the valve member is mounted to the base, wherein the valve member is deflectable relative to the base between a closed position in which the valve member restricts fluid flow through the discharge opening and an open position in which the valve member allows fluid flow through the discharge opening, wherein a first side of the base includes a first seat surface and a second seat surface that is recessed from the first seat surface, wherein the discharge opening extends through the first and second seat surfaces, wherein a movable end of the valve member contacts the first seat surface when the valve member is in the closed position and is spaced apart from the first seat surface when the valve member is in the open position, and wherein the movable end of the valve member contacts the second seat surface when the valve member is in the closed position and is spaced apart from the second seat surface when the valve member is in the open position.

13. The compressor of claim 12, wherein the discharge valve assembly includes a backer fixed relative to the base, wherein the valve member is disposed between the backer and the base, and wherein the backer defines a range of motion of the valve member.

14. The compressor of claim 13, wherein the backer is configured to allow a maximum deflection of a distal tip of a movable end of the valve member of about 6.7 millimeters to about 13.5 millimeters.

15. The compressor of claim 12, wherein the discharge opening includes a plurality of radially extending lobes.

16. The compressor of claim 15, radially extending lobes are evenly spaced around a circle defined by radially inner portions of a surface that defines a periphery of the discharge opening.

17. The compressor of claim 12, wherein the scroll is a non-orbiting scroll.

Description

DRAWINGS

(1) The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations and are not intended to limit the scope of the present disclosure.

(2) FIG. 1 is a cross-sectional view of a compressor according to the principles of the present disclosure;

(3) FIG. 2 is a partial cross-sectional view of a compression mechanism of the compressor of FIG. 1 with a discharge valve assembly in a closed position;

(4) FIG. 3 is another partial cross-sectional view of the compression mechanism with the discharge valve assembly in an open position;

(5) FIG. 4 is a plan view of a non-orbiting scroll of the compressor of FIG. 1;

(6) FIG. 5 is perspective view of the discharge valve assembly according to the principles of the present disclosure;

(7) FIG. 6 is an exploded perspective view of the discharge valve assembly of FIG. 5;

(8) FIG. 7 is a plan view of a base of the discharge valve assembly of FIG. 5;

(9) FIG. 8 is a cross-sectional view of the base, a spacer, and a reed valve member of the discharge valve assembly in a closed position;

(10) FIG. 9 is a plan view of the base, the spacer, and the reed valve member of the discharge valve assembly in a closed position; and

(11) FIG. 10 is a graph of the opening distances of an exemplary reed valve member.

(12) Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

(13) Example embodiments will now be described more fully with reference to the accompanying drawings.

(14) Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

(15) The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms a, an, and the may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms comprises, comprising, including, and having, are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

(16) When an element or layer is referred to as being on, engaged to, connected to, or coupled to another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being directly on, directly engaged to, directly connected to, or directly coupled to another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., between versus directly between, adjacent versus directly adjacent, etc.). As used herein, the term and/or includes any and all combinations of one or more of the associated listed items.

(17) Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as first, second, and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

(18) Spatially relative terms, such as inner, outer, beneath, below, lower, above, upper, and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as below or beneath other elements or features would then be oriented above the other elements or features. Thus, the example term below can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

(19) With reference to FIG. 1, a scroll compressor 10 is provided that may include a shell assembly 12, a discharge fitting 14, a suction inlet fitting 16, a motor assembly 18, a bearing housing assembly 20, a compression mechanism 22, a floating seal assembly 26, and a discharge valve assembly 28. As will be described in more detail below, the discharge valve assembly 28 is movable between a closed position (FIG. 2) in which the discharge valve assembly 28 restricts a flow of discharge-pressure working fluid and an open position (FIG. 3) in which the discharge valve assembly 28 allows discharge-pressure working fluid to be discharged from the compression mechanism 22.

(20) The shell assembly 12 may house the motor assembly 18, the bearing housing assembly 20, the compression mechanism 22, the floating seal assembly 26, and the discharge valve assembly 28. The shell assembly 12 may include a generally cylindrical shell 34, an end cap 36, a transversely extending partition 37, and a base 38. The end cap 36 may be fixed to an upper end of the shell 34. The base 38 may be fixed to a lower end of shell 34. The end cap 36 and partition 37 may define a discharge chamber 42 therebetween that receives compressed working fluid from the compression mechanism 22. The partition 37 may include an aperture 39 providing communication between the compression mechanism 22 and the discharge chamber 42. The discharge chamber 42 may generally form a discharge muffler for the compressor 10.

(21) The discharge fitting 14 may be attached to the end cap 36 and is in fluid communication with the discharge chamber 42. The suction inlet fitting 16 may be attached to the shell 34 and may be in fluid communication with a suction chamber 43. While the compressor 10 is shown in FIG. 1 as including the discharge chamber 42 and suction chamber 43, it will be appreciated that the present disclosure is not limited to compressors having discharge chambers and/or suction chambers and applies equally to direct discharge configurations and/or direct or directed suction configurations.

(22) The motor assembly 18 may include a motor stator 44, a rotor 46, and a drive shaft 48. The stator 44 may be press fit into the shell 34. The drive shaft 48 may be rotatably driven by the rotor 46 and supported by the bearing housing assembly 20. The drive shaft 48 may include an eccentric crank pin 52 having a flat thereon for driving engagement with the compression mechanism 22. The rotor 46 may be press fit on the drive shaft 48. The bearing housing assembly 20 may include a main bearing housing 54 and a lower bearing housing 56 fixed within the shell 34. The bearing housings 54, 56 may be fixed relative to the shell assembly 12 and may house bearings that rotatably support the drive shaft 48. The main bearing housing 54 may include an annular flat thrust bearing surface 58 that supports the compression mechanism 22 thereon.

(23) The compression mechanism 22 may be driven by the motor assembly 18 and may generally include an orbiting scroll 60 and a non-orbiting scroll 62. The orbiting scroll 60 may include an end plate 64 having a spiral vane or wrap 66 on the upper surface thereof and an annular flat thrust surface 68 on the lower surface. The thrust surface 68 may interface with an annular flat thrust bearing surface 58 on the main bearing housing 54. A cylindrical hub 70 may project downwardly from the thrust surface 68 and may have a drive bushing 72 disposed therein. The drive bushing 72 may include an inner bore in which the crank pin 52 is drivingly disposed. The crank pin 52 may drivingly engage a flat surface in a portion of the inner bore of the drive bushing 72 to provide a radially compliant driving arrangement.

(24) As shown in FIGS. 2-4, the non-orbiting scroll 62 may include an end plate 78 and a spiral wrap 80 extending from a first side 82 of the end plate 78. A second side 84 of the end plate 78 may include a first annular wall 86 and a second annular wall 90. The first and second annular walls 86, 90 cooperate to define an annular recess 88. The second annular wall 90 may be disposed radially inward relative to the first annular wall 86 and may define a discharge recess 92. The annular recess 88 may encircle the discharge recess 92 and may be substantially concentric therewith. As shown in FIGS. 2 and 3, a discharge passage 94 may extend through the end plate 78 from the first side 82 to the discharge recess 92.

(25) As shown in FIG. 4, the end plate 78 may include a pair of bores 116. In some embodiments, the bores 116 may be blind, non-threaded holes formed in the discharge recess 92 that extend only partially through the end plate 78. In some embodiments, the bores 116 may be threaded holes formed in the discharge recess 92 that extend only partially through the end plate 78.

(26) Returning to FIG. 1, the non-orbiting scroll 62 may be rotationally secured to the main bearing housing 54 by a retaining assembly 120. The retaining assembly 120 allows for limited axial displacement of the non-orbiting scroll 62 relative to the orbiting scroll 60 and the main bearing housing 54 based on pressurized gas from biasing passage 100. The retaining assembly 120 may include a plurality of fasteners 122 and bushings 124 extending through apertures in the non-orbiting scroll 62. The fasteners 122 may fixedly engage the main bearing housing 54. The non-orbiting scroll 62 may be axially moveable along the bushings 124 relative to the fasteners 122.

(27) The spiral wrap 80 of the non-orbiting scroll 62 may meshingly engage the spiral wrap 66 of the orbiting scroll 60, thereby creating a series of pockets therebetween. The fluid pockets defined by the spiral wraps 66, 80 may decrease in volume as they move from a radially outer position (at a suction pressure) to a radially intermediate position (at an intermediate pressure) to a radially inner position (at a discharge pressure) throughout a compression cycle of the compression mechanism 22. The discharge passage 94 may be in fluid communication with the fluid pocket 123 at the radially inner position. When the discharge valve assembly 28 is in the open position (FIG. 2), working fluid from the fluid pocket 123 at the radially inner position (discharge-pressure working fluid) may flow through the discharge passage 94, through the discharge valve assembly 28, through the discharge recess 92 and into the discharge chamber 42. The biasing passage 100 in the end plate 78 may be in fluid communication with the fluid pocket 125 at the radially intermediate position.

(28) The floating seal assembly 26 may be disposed within the annular recess 88 and may sealingly engage the first annular wall 86, second annular wall 90, and the partition 37 to form an annular biasing chamber 148. The annular biasing chamber 148 is isolated from the suction and discharge chambers 43, 42 and is in communication with the fluid pocket 125 at the radially intermediate position via the biasing passage 100. During operation of the compressor 10, the biasing chamber 148 may be filled with intermediate-pressure working fluid from the fluid pocket 125 at the radially intermediate position, which biases the non-orbiting scroll 62 in an axial direction toward the orbiting scroll 60.

(29) The discharge valve assembly 28 may be received in the discharge recess 92 of the non-orbiting scroll 62 and may control fluid flow through the discharge passage 94. As shown in FIGS. 5 and 6, the discharge valve assembly 28 may include a base 149, a reed valve member 150, a spacer 151, and a backer 152.

(30) As shown in FIGS. 5-7, the base 149 may be a disk-shaped member having a discharge opening 154 and a pair of bores 155 extending therethrough. The bores 155 may be coaxially aligned with the bores 116 of the end plate 78. The base 149 may be seated against the end plate 78 such that the discharge opening 154 is generally aligned with the discharge passage 94, as shown in FIGS. 2 and 3.

(31) A surface 156 defining a periphery of the discharge opening 154 may include one or more extensions 157 (or lobes) extending radially outward from radially inner portions 169 of the surface 156 that define an inner circle 158 (shown in dashed lines in FIG. 7). The one or more extensions 157 may be generally curved such that the surface 156 of the discharge opening 154 is curved. The extensions 157 may extend radially outward from the inner circle 158 to form a generally flower shape of the discharge opening 154. In some embodiments, the extensions 157 are evenly spaced around the discharge opening 154. In other embodiments, one or pairs of adjacent extensions 157 may be spaced further apart from each other than one or more other pairs of adjacent extensions 157. In some embodiments, such as the embodiment shown in FIGS. 5-7, the discharge opening 154 includes four extensions 157. However, in some embodiments there may be as few as one extension or as many as six extensions. In some embodiments, one or more of the extensions 157 may have a different size and/or shape than one or more other extensions 157. The discharge opening 154 having one or more of the extensions 157 may improve the flow of compressed working fluid from the discharge passage 94 to the discharge chamber 42. In some embodiments, the positioning of the extensions 157 around the inner circle 158 may be different from the positioning shown in the figures (e.g., to optimize load distribution, for example).

(32) The base 149 may include a first seat surface (or upper seat surface) 163 and a second seat surface (or recessed seat surface) 159 on a first side 160 of the base 149. The first seat surface 163 may surround the second seat surface 159. The spacer 151 may be mounted to the first seat surface 163. The first side 160 of the base 149 may be the side adjacent to the reed valve member 150 when the discharge valve assembly 28 is assembled. The second seat surface 159 may be recessed from the first seat surface 163 of the base 149. In other words, the second seat surface 159 may be a counterbore in the first side 160 of the base 149 surrounding the discharge opening 154. A thickness 161 of the base 149 at the second seat surface 159 may be less than a thickness 162 of the base 149 at the first seat surface 163 surrounding the second seat surface 159. In some configurations, the thickness 161 at the second seat surface 159 may be between 0.02 millimeters and 0.1 millimeters thinner than the thickness 162 at the first seat surface 163. The second seat surface 159 may have a circular outer periphery 166. The second seat surface 159 may extend between the extensions 157 of the discharge opening 154. In some embodiments, the second seat surface 159 may surround the entirety of the discharge opening 154. In other embodiments, the outer periphery 166 of the second seat surface 159 may be at least partially defined by radially outer portions 167 of the surface 156 of the extensions 157 of the discharge opening 154.

(33) In some configurations, the base 149 could include another recessed surface (similar to the second seat surface 159) on the side of the base 149 opposite the side 160. Such a recessed surface may at least partially surround the opening 154 in the same or similar manner as the second seat surface 159.

(34) As shown in FIGS. 5 and 6, the reed valve member 150 may be a thin, resiliently flexible member having a fixed end 170 and a movable end 171. A pair of arms 172 may extend from the fixed end 170 and may each include a bore 173. The reed valve member 150 may be seated against the spacer 151, which in turn, may be seated against the base 149 such that the bores 173 are coaxially aligned with the bores 155 in the base 149. The movable end 171 of the reed valve member 150 is deflectable relative to the fixed end 170 between the closed position (FIG. 2) in which the movable end 171 sealingly seats against the base 149 to restrict or prevent fluid flow through the discharge opening 154 (thereby preventing fluid flow through the discharge passage 94) and the open position (FIG. 3) in which the movable end 171 is deflected upward away from the base 149 and toward the backer 152 to allow fluid flow through the discharge passage 94 and the discharge opening 154.

(35) The reed valve member 150 may be moved to the open position due to a pressure differential on opposing sides of the reed valve member 150, such as when the pressure within the discharge passage 94 (and fluid pocket 123) exceeds the pressure within the discharge chamber 42. An amount of deflection of the movable end 171 of the reed valve member 150 may vary based on a distance from the fixed end 170. For example, the amount of deflection may be larger in portions of the movable end 171 of the reed valve member 150 which are farther away from the fixed end 170. The fixed end 170 may be fixed by the backer 152 being coupled to the base 149 (i.e., the fixed end 170 is sandwiched between the backer 152 and the base 149). A maximum amount of deflection of the movable end 171 may occur at a portion 175 of the movable end 171 of the reed valve member 150 furthest from the fixed end 170. In some embodiments, the portion 175 of the movable end 171 of the reed valve member 150 furthest from the fixed end 170 may be about 30 millimeters from the fixed end 170.

(36) The movable end 171 of the reed valve member 150 may move to the closed position by moving in a downward direction toward the first and second seat surfaces 163, 159 due to the pressure in the discharge chamber 42 increasing relative to the pressure within the discharge passage 94 and/or due to pressure within the discharge passage 94 decreasing relative to the pressure in the discharge chamber 42, which allows the spring force of the resiliently flexible reed valve member 150 to force the movable end 171 toward the closed position. In the closed position, the reed valve member 150 restricts or prevents fluid flow between the discharge chamber 42 and the discharge passage 94.

(37) As shown in FIGS. 8 and 9, the movable end 171 of the reed valve member 150 may seal against the first seat surface 163 of the base 149 adjacent to the outer periphery 166 of the second seat surface 159 when in the closed position. Under some operating conditions, the movable end 171 of the reed valve member 150 may also seal against the second seat surface 159 as the movable end 171 deforms into the discharge opening 154 due to the pressure differential between the discharge chamber 42 and the discharge passage 94. Dashed lines in FIG. 9 show locations on which the reed valve member 150 may seal against the first seat surface 163 and the second seat surface 159, respectively, when in the closed position. The movable end 171 of the reed valve member 150 sealing against the first seat surface 163 and against the second seat surface 159 may provide an improved seal when the movable end 171 of the reed valve member 150 is in the closed position. This improved seal may reduce or eliminate leakage of working fluid through the discharge valve assembly 28 when the movable end 171 of the reed valve member 150 is in the closed position, thus improving efficiency of the discharge valve assembly 28 and the compressor 10.

(38) The combination of the shape of the discharge opening 154 and the recessed second seat surface 159 may result in significant performance improvements relative to prior-art discharge valves (e.g., better sealing in the closed position and better fluid flow in the open position). For example, the extensions 157 increase the flow area (or port area) of the discharge opening 154 without increasing an unsupported span distance of the reed valve member 150 (i.e., the diameter of the inner circle 158 or a maximum distance over which the reed valve member 150 spans the discharge opening 154 between points of contact between the reed valve member 150 and the second seat surface 159). In the particular example shown in the figures, the flow area of the discharge opening 154 is approximately 106 mm.sup.2 (106 square millimeters) and the unsupported span distance is about 8.58 mm. By contrast, a similarly sized discharge opening (i.e., with unsupported span distance of 8.58 mm) that does not have the extensions 157 would have a flow area of approximately 57.8 mm.sup.2 (57.8 square millimeters). Therefore, the discharge opening 154 with the extensions 157 significantly increases the flow area (which improves fluid flow when the reed valve member 150 is in the open position) without increasing the unsupported span distance (which allows for better sealing and reduces stresses when the reed valve member 150 is in the closed position). Such performance improvements increase the overall efficiency of the compressor 10, which reduces energy consumption and improves operation of the climate-control system in which the compressor 10 is installed.

(39) Returning to FIG. 6, the spacer 151 may include a pair of arms 177 shaped to correspond to the arms 172 of the reed valve member 150. Each of the arms 177 may include a bore 178 coaxially aligned with corresponding ones of the bores 173, 155. The spacer 151 may be disposed between the base 149 and the reed valve member 150 to create a space between the movable end 171 and the discharge opening 154. The movable end 171 of the reed valve member 151 may move into this space when entering the closed position to seal the discharge opening 154.

(40) The backer 152 may include a body 179 having a pair of bores 180 extending therethrough. The body 179 may include a lobe portion 181 shaped to correspond to the shape of the movable end 171 of the reed valve member 150. The lobe portion 181 may include an inclined surface 182 that faces the reed valve member 150 and forms a valve stop that defines a maximum amount of deflection of the movable end 171 of the reed valve member 150. The inclined surface 182 may be shaped to allow the reed valve member 150 to open to a greater extent than traditional discharge valve assemblies while limiting stress in the reed valve member 151. Such an expanded opening may allow for increased flow of the working fluid through the discharge passage 94 and through the discharge valve assembly 28. Such increased fluid flow improves the efficiency of the compressor 10, which reduces energy consumption and improves operation of the climate-control system in which the compressor 10 is installed.

(41) FIG. 10 provides a graph showing ranges to which the movable end 171 of the reed valve member 150 may move between the closed position and the open position. These ranges may be determined by the shape of the lobe portion 181 of the backer 152. In some embodiments, the inclined surface 182 of the lobe portion 181 may be configured to allow the movable end 171 of the reed valve member 150 to deflect to a maximum deflection between 6.7 millimeters and 13.5 millimeters (at a distal tip of the movable end 171). In some embodiments, the inclined surface 182 of the lobe portion 181 may be configured to allow a point on the reed valve member 150 which is about 25 millimeters from the fixed end 170 to deflect between about 5.3 millimeters and about 10.6 millimeters from the closed position.

(42) In some embodiments, the inclined surface 182 of the lobe portion 181 may be configured to allow a point on the reed valve member 150 which is about 20 millimeters from the pivot point 174 to deflect between about 3.6 millimeters and about 7.7 millimeters from the closed position. In some embodiments, the inclined surface 182 of the lobe portion 181 may be configured to allow a point on the reed valve member 150 which is about 15 millimeters from the pivot point 174 to deflect between about 2 millimeters and about 4.8 millimeters from the closed position. In some embodiments, the inclined surface 182 of the lobe portion 181 may be configured to allow a point on the reed valve member 150 which is about 10 millimeters from the pivot point 174 to deflect between about 0.9 millimeters and about 2.1 millimeters from the closed position.

(43) Fasteners may pass through the bores 116, 155, 173, 178, 180 to secure the discharge valve assembly 28 to the end plate 78. In some embodiments, the fasteners may be threaded. In some embodiments, the fasteners may be spiral pins having resiliently contractable diameters to facilitate insertion into the bores 116, 155, 173, 178, 180. In some embodiments, pins may be press fit in the non-threaded bores 116, 155, 173, 178, 180 to secure the discharge valve assembly 28 to the end plate 78.

(44) The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.