RECIPROCATING COMPRESSOR AND FLUID INJECTION SYSTEM

Abstract

A compressor includes a housing, a first compression mechanism and a second compression mechanism disposed in the housing, and a housing cover fixed to the housing. Both the first compression mechanism and the second compression mechanism are configured to compress a working fluid from a suction pressure to a discharge pressure. The first compression mechanism includes a first cylinder housing having a first fluid storage plenum. The second compression mechanism includes a second cylinder housing having a second fluid storage plenum. The housing cover defines an intermediate-fluid port in fluid communication with the first fluid storage plenum via a first intermediate-fluid passage and the second fluid storage plenum via a second intermediate-fluid passage. Working fluid at an intermediate pressure enters the intermediate-fluid port. The intermediate pressure is greater than the suction pressure and less than the discharge pressure.

Claims

1. A compressor comprising: a housing; a first compression mechanism disposed in the housing and configured to compress a working fluid from a suction pressure to a discharge pressure, the first compression mechanism including a first cylinder housing having a first cylinder, a second cylinder, and a first fluid storage plenum; a second compression mechanism disposed in the housing and configured to compress the working fluid from the suction pressure to the discharge pressure, the second compression mechanism including a second cylinder housing having a third cylinder, a fourth cylinder, and a second fluid storage plenum; and a housing cover fixed to the housing and defining an intermediate-fluid port therein, the intermediate-fluid port being in fluid communication with the first fluid storage plenum via a first intermediate-fluid passage and the second fluid storage plenum via a second intermediate-fluid passage, wherein: working fluid at an intermediate pressure enters the intermediate-fluid port, the intermediate pressure is greater than the suction pressure and less than the discharge pressure, the first fluid storage plenum and the second fluid storage plenum are configured to store the fluid at the intermediate pressure therein.

2. The compressor of claim 1, wherein the housing cover further includes: a body defining an outer diameter and an inner diameter spaced radially inward from the outer diameter, a first surface and a second surface opposite the first surface, the first surface and the second surface defining a thickness therebetween, and a third surface protruding axially from the second surface, wherein the second surface and the third surface cooperate to define a cavity therebetween.

3. The compressor of claim 2, wherein the cavity is in fluid communication with the intermediate-fluid port.

4. The compressor of claim 3, wherein the second surface of the housing cover defines a plurality of apertures positioned between the outer diameter and the inner diameter, each of the plurality of apertures extending partially through the body to a depth that is less than the thickness.

5. The compressor of claim 4, wherein a channel extends radially inward from each of the plurality of apertures to the inner diameter, each of the channels being in fluid communication with the cavity.

6. The compressor of claim 5, wherein each of the channels includes an intermediate-fluid inlet proximate to the inner diameter and an intermediate-fluid outlet proximate to one of the plurality of apertures, wherein the fluid at the intermediate pressure flows through the channel from the intermediate-fluid inlet to the intermediate-fluid outlet.

7. (canceled)

8. The compressor of claim 6, wherein each of the plurality of apertures are in fluid communication with the cavity via the channel.

9. The compressor of claim 8, wherein the plurality of apertures includes a first aperture in fluid communication with the first intermediate-fluid passage and a second aperture in fluid communication with the second intermediate-fluid passage.

10. The compressor of claim 8, wherein the fluid at the intermediate pressure flows from the intermediate-fluid port, through the cavity, through the plurality of apertures, and through the first intermediate-fluid passage and the second intermediate-fluid passage to the respective first storage plenum and second storage plenum.

11. The compressor of claim 10, wherein the first fluid storage plenum is in selective fluid communication with the first cylinder and the second cylinder, and the second fluid storage plenum is in selective fluid communication with the third cylinder and the fourth cylinder.

12. The compressor of claim 11, wherein each of the first cylinder, second cylinder, third cylinder, and fourth cylinder include a sleeve assembly disposed therein, the sleeve assembly including a sleeve and a collar.

13. The compressor of claim 12, wherein the sleeve includes: a hollow body including an annular wall extending between a first end and a second end, the hollow body including an inner surface and an outer surface opposite the inner surface, a flange extending radially outward from the first end of the annular wall, a step positioned between a first portion of the hollow body and a second portion of the hollow body, wherein a diameter of the outer surface of the first portion is greater than a diameter of the outer surface of the second portion, a plurality of recesses defined in the first portion, and a plurality of apertures defined in the second portion.

14. The compressor of claim 13, wherein the collar includes: an annular member extending between a first end and a second end and including an outer surface and an inner surface opposite the outer surface, a first plurality of protrusions extending axially from the second end, a second plurality of protrusions extending axially from the first end, and a plurality of depressions defined in the inner surface, each of the plurality of depressions positioned between each of the first plurality of protrusions.

15. The compressor of claim 14, wherein: the first end of the collar is in contact with the step of the sleeve, the second plurality of protrusions of the collar are received in the plurality of recesses of the sleeve, and the plurality of depressions of the collar are aligned with and spaced apart from the plurality of apertures of the sleeve.

16. The compressor of claim 15, wherein the plurality of depressions of the collar and the plurality of apertures of the sleeve cooperate to define a plurality of ports therebetween.

17. The compressor of claim 16, wherein each of the first cylinder, the second cylinder, the third cylinder, and the fourth cylinder receive a piston therein, the piston movable between a first position and a second position, wherein the piston and the sleeve assembly cooperate to selectively permit the fluid at the intermediate pressure to enter the respective cylinder.

18. The compressor of claim 17, wherein when the piston is in the first position, the fluid at the intermediate pressure enters the cylinder through the plurality of ports.

19. The compressor of claim 17, wherein when the piston is in the second position, the fluid at the intermediate pressure is restricted from entering the cylinder.

20. A compressor comprising: a housing; a compression mechanism disposed in the housing and configured to compress a working fluid from a suction pressure to a discharge pressure; and a housing cover attached to the housing, the housing cover comprising: a circular body defining an outer diameter and an inner diameter spaced radially inward from the outer diameter, the circular body including a first surface and a second surface opposite the first surface; a third surface protruding axially from the second surface along at least a portion of the inner diameter, the second surface and the third surface cooperating to define a cavity therebetween; and a fluid port extending between the first surface and the second surface, wherein the fluid port is configured to receive working fluid at an intermediate pressure and to provide the fluid at the intermediate pressure to the compression mechanism, wherein the intermediate pressure is greater than the suction pressure and less than the discharge pressure.

21. The compressor of claim 20, wherein the second surface defines a plurality of apertures positioned between the outer diameter and the inner diameter, each of the plurality of apertures extending partially through the circular body.

22. The compressor of claim 21, wherein a channel extends radially inward from each of the plurality of apertures to the inner diameter, the channel being in fluid communication with the cavity.

23. The compressor of claim 22, wherein the channel includes an intermediate-fluid inlet proximate to the inner diameter and an intermediate-fluid outlet proximate to one of the plurality of apertures, wherein the fluid at the intermediate pressure flows through the channel from the intermediate-fluid inlet to the intermediate-fluid outlet.

24. The compressor of claim 22, wherein at least one of the plurality of apertures is in fluid communication with the compression mechanism via an intermediate-fluid passage.

25.-50. (canceled)

Description

DRAWINGS

[0057] 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.

[0058] FIG. 1 is a perspective view of a compressor according to the principles of the present disclosure;

[0059] FIG. 2 is an exploded view of the compressor of FIG. 1;

[0060] FIG. 3A is a perspective view of a sleeve assembly of the compressor of FIGS. 1-2;

[0061] FIG. 3B is an exploded view of the sleeve assembly of FIG. 3A;

[0062] FIG. 3C is a cross-sectional view of the sleeve assembly of

[0063] FIG. 3A taken along line 3C-3C of FIG. 1;

[0064] FIG. 3D is a bottom view of a collar of the sleeve assembly of FIGS. 3A-3C;

[0065] FIG. 3E is a partial cross-sectional view of the collar of FIG. 3D taken along line 3E-3E of FIG. 3D;

[0066] FIG. 4A is a perspective view of a piston of the compressor of FIG. 1-2;

[0067] FIG. 4B is a top view of the piston of FIG. 4A;

[0068] FIG. 4C is a cross-sectional view of the piston of FIG. 4A;

[0069] FIG. 5A is a partial cross-sectional view of the piston, sleeve assembly, and a cylinder of the compressor of FIGS. 1-2 when the piston is in a first position;

[0070] FIG. 5B is a partial cross-sectional view of the piston, sleeve assembly, and cylinder of FIG. 5A when the piston is in a second position;

[0071] FIG. 6 is a schematic showing of a fluid flow path of a fluid injection system of the compressor of FIGS. 1-2 according to principles of the present disclosure;

[0072] FIGS. 7A-7G are views of a housing cover of the compressor of FIGS. 1-2;

[0073] FIG. 8A is a schematic cross-sectional view of the piston, sleeve assembly, and cylinder of FIGS. 1-2 when the piston is in the first position;

[0074] FIG. 8B is a schematic cross-sectional view of the piston, sleeve assembly, and cylinder of FIG. 8A when the piston is in the second position;

[0075] FIG. 9 is a perspective view of another compressor according to the principles of the present disclosure;

[0076] FIG. 10 is an exploded view of the compressor of FIG. 9; and

[0077] FIG. 11 is a cross-sectional view of a portion of a fluid injection system of the compressor of FIG. 9, taken along line 11-11 of FIG. 9, according to the principles of the present disclosure.

[0078] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION

[0079] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] With reference to FIGS. 1-2, a reciprocating compressor assembly 10 (the compressor 10) is provided that may include a compressor housing 12, a housing cover 14, an end cap 15, an inlet port 16, and a discharge port 18. The housing cover 14 and the end cap 15 may be fixed to the compressor housing 12 (e.g., via fasteners). The end cap 15 defines the inlet port 16.

[0086] The compressor 10 further includes a first cylinder housing or deck 22 (FIG. 2) and a second cylinder housing or deck 24 positioned within the compressor housing 12. The compressor housing 12 and decks 22, 24 cooperate to contain a first compression mechanism 30 (FIG. 1) and a second compression mechanism 31, respectively. The first and second compression mechanisms 30, 31 selectively compress a working fluid (e.g., refrigerant, carbon dioxide, oil, etc.) from a suction pressure to a discharge pressure. Specifically, the first compression mechanism 30 and the second compression mechanism 31 cooperate to receive a working fluid from the inlet port 16 at a suction pressure and may increase the pressure of the working fluid from the suction pressure to a discharge pressure.

[0087] A first cylinder head 32 (FIG. 2), one or more cylinder head gaskets 34, a first valve plate 36, a first deck plate 38 and one or more deck gaskets 40 may be fixed to the first deck 22 and cooperate to seal the first compression mechanism 30 and the compressor housing 12 from outside contaminants. The first deck plate 38 may include two recessed apertures 42. A first fluid inlet 42 (FIG. 6), a first fluid-storage plenum 44 (FIG. 2 and FIG. 6) (e.g., a vapor-storage plenum) (hereafter the first storage plenum 44), a first cylinder 46 and a second cylinder 48 are defined in the compressor housing 12 adjacent to the first deck 22. The first cylinder 46 and the second cylinder 48 may be aligned with the recessed apertures 42 of the deck plate 38.

[0088] Similarly, a second cylinder head 52, one or more second cylinder plate gaskets, a second valve plate, a second deck plate and second deck plate gaskets (not shown, see, e.g., first cylinder plate gaskets 34, first valve plate 36, first deck plate 38, and first deck plate gaskets 40) cooperate to seal the second compression mechanism 31 and the compressor housing 12 from outside contaminants. A second fluid inlet 56 (FIG. 6), a second fluid-storage plenum 58 (hereafter the second storage plenum 58) (FIG. 6), a third cylinder 66 and a fourth cylinder 68, are defined in the compressor housing 12 adjacent to the second deck 24. A sleeve assembly 69 is received in each of the cylinders 46, 48, 66, 68. Specifically the sleeve assembly 69 is seated in one of the recessed apertures 42 of the first deck plate 38 and the second deck plate. The sleeve assembly 69 will be described in greater detail below in the discussion accompanying FIGS. 3A-3E.

[0089] A first and second piston 74, 75, of the first compression mechanism 30 and a third and fourth piston 76, 77 of the second compression mechanism 31 are located within the compressor housing 12 and are reciprocally movable in linear directions by respective connecting rods 78. The first piston 74 is seated in the sleeve assembly 69 of the first cylinder 46, the second piston 75 is seated in the sleeve assembly 69 of the second cylinder 48, the third piston 76 is seated in the sleeve assembly 69 of the third cylinder 66, and the fourth piston 77 is seated in the sleeve assembly 69 of the fourth cylinder 68. The connecting rods 78 are disposed between the respective pistons 74, 75, 76, 77 and a crankshaft 79 to allow a rotational force applied to the crankshaft 79 to be transmitted to pistons 74, 75, 76, 77. While compressor 10 shown in the figures includes two compression mechanisms 30, 31 and four pistons 74, 75, 76, 77, it is contemplated that the compressor 10 could include any number of compression mechanisms and pistons.

[0090] With reference to FIGS. 3A-3E, the sleeve assembly 69 includes a sleeve 80 and a collar 82. The sleeve 80 includes an annular wall 84 extending between a first end 85 and a second end 86. The annular wall 84 may have an outer surface 88 and an inner surface 90 opposite the outer surface 88. A step 91 (FIGS. 3B and 3C) extends around periphery of the annular wall 84 and separates a first or upper portion 92 of the annular wall 84 from a second or lower portion 94 of the annular wall 84. A first thickness 96 of the first portion 92 is greater than a second thickness 98 of the second portion 94. It follows that a first diameter of the outer surface 88 of the first portion 92 is greater than a second diameter of the outer surface 88 of the second portion 94. A flange 102 extends radially outward from the first end 85. As shown in FIGS. 5A-5B, a surface 103 of the flange 102 may be configured to be seated in or contact a surface 104 of the recessed apertures 42 of the deck plate 38. In this way, the annular wall 84 of the sleeve 80 is received in one of the cylinders 46, 48, 66, 68. The outer surface 88 of the sleeve 80 may contact or be slightly spaced apart from the respective cylinder 46, 48, 66, 68.

[0091] The first portion 92 of the annular wall 84 may define one or more recesses 105 (e.g., notches) (FIG. 3B) proximate to the step 91. The recesses 105 may include a first recess and a second recess opposite the first recess (neither shown). The recesses 105 may have a generally rectangular shape, although other shapes and configurations are contemplated.

[0092] One or more apertures 110 (FIGS. 3B and 3C) may be defined in the second portion 94. The one or more apertures 110 may be positioned proximate to the step 91. The one or more apertures 110 may extend longitudinally from a first end 111 (FIG. 3C) to a second end 112. In the configuration of FIGS. 3A-3C, six apertures 110 are evenly spaced around the periphery of the annular wall 84. However, it is contemplated that there may be more or fewer apertures 110 and/or apertures with varied (e.g., non-uniform) spacing defined in the annular wall 84.

[0093] The sleeve assembly 69 may further include a seal 142 circumscribing the sleeve 80. The seal 142 may be disposed within a groove 144 defined in the second portion 94 of the sleeve 80. The seal 142 may be positioned between the second end 86 and the plurality of apertures 110.

[0094] The collar 82 is an annular member 120. The annular member 120 extends axially between a first end 122 and a second end 124 opposite the first end 122. The annular member 120 has an outer surface 126 and an inner surface 128 opposite the outer surface 126. A first plurality of protrusions 130 extend axially from the second end 124. The first plurality of protrusions 130 have a generally rectangular shape, although other shapes and configurations are possible. In the configuration of FIGS. 3A-3E, the first plurality of protrusions 130 includes six protrusions. However, it is contemplated that there may be more or fewer first plurality of protrusions 130.

[0095] The inner surface 128 defines a plurality of depressions or recesses 131 positioned between each of the first plurality of protrusions 130. As will be described in greater detail below, each of the plurality of depressions 131 are configured to be aligned with the one or more apertures 110 of the sleeve 80. In the configuration of FIGS. 3A-3E, the first plurality of depressions 131 includes six depressions corresponding to the six apertures 110. A dimension 132 of each of the plurality of depressions 131 may be greater than a dimension 133 of the apertures 110 such that when the plurality of depressions 131 and the apertures 110 are aligned the plurality of depressions 131 covers substantially all of the respective aperture 110.

[0096] A second plurality of protrusions 134 may extend axially from the first end 122. The second plurality of protrusions 134 may include a first protrusion 136 and a second protrusion 138 positioned opposite the first protrusion. As will be described in greater detail below, the second plurality of protrusions 134 are configured to be received in the recesses 105 of the sleeve 80. The shape or profile of the second plurality of protrusions 134 may be complimentary to the shape of the recesses 105 of the sleeve 80.

[0097] The collar 82 is configured to engage the sleeve 80 (e.g., via a snap-fit). As best shown in FIG. 3A, the second plurality of protrusions 134 of the collar 82 are received in the plurality of recesses 105 of the sleeve 80. The first end 122 of the collar 82 contacts the step 91 of the sleeve 80 (FIG. 3C). In this way, the inner surface 128 of the collar 82 contacts the outer surface 88 of the second portion 94 of the sleeve 80.

[0098] The plurality of depressions 131 of the collar 82 are aligned with the apertures 110 of the sleeve 80. The inner surface 128 of the collar 82 at the plurality of depressions 131 is spaced apart from the outer surface 88 of the sleeve 80. The plurality of depressions 131 and the apertures 110 cooperate to define a plurality of ports 140 (e.g., intermediate-fluid ports). As will be described in the discussion accompanying FIGS. 5A-5B, the intermediate-fluid ports 140 are configured to selectively permit fluid at an intermediate pressure to flow into the cylinders 46, 48, 66, 68 during operation of the compressor 10. The plurality of intermediate-fluid ports 140 may include six ports corresponding to the six apertures 110 and six depressions 131.

[0099] With reference to FIGS. 4A-4C, the piston 74 (which is the same as pistons 75, 76, 77) may include a hollow cylindrical body 150 including a top wall 152 and a side wall 154 extending perpendicularly from the top wall 152. The side wall 154 includes an outer surface 156 and an inner surface 158 (FIG. 4C) opposite the outer surface 156. The side wall 154 defines a first aperture 160 and a second aperture 162 opposite the first aperture 160. The first and second apertures 160, 162 may be generally circular in shape although other shapes and configurations are possible. A plurality of grooves 164 may be defined in the side wall 154 proximate to the top wall 152. A distal groove 177 may be defined in the side wall 154 proximate to an annular end 165 of the side wall 154. The piston may further include a seal 176 circumscribing the side wall 154 and disposed within the distal groove 177. One or more additional seals (not shown) may be disposed in the plurality of grooves 164. The seal 176 and the one or more additional seals may be formed of a metallic material. While the seal 176 shown in FIGS. 4A-4C has a generally circular cross-section, other shapes are contemplated (e.g., seals with rectangular cross-sections).

[0100] The top wall 152 may define one or more ports 166 (e.g., valving clearance reliefs) extending from a first side of the top wall 152 to an opposite side of the top wall 152. The top wall 152 defines a plurality of chamfered recesses 168 spaced apart around the perimeter of the top wall 152 (e.g., at the intersection of the top wall 152 and side wall 154). In the configuration of FIGS. 4A-4C there are six chamfered recesses 168 to correspond to the six plurality of intermediate-fluid ports 140 of the sleeve assembly 69. Each of the chamfered recesses 168 extend between a first end 173 and a second end 174. The chamfered recesses define a first angle 172 (FIG. 4B) relative to a perimeter of the top wall 152. The first angle 172 may correlate to the dimension 133 of the apertures 110 of the sleeve 80. For example, the first angle 172 may be relatively larger when the dimension 133 of the apertures 110 is larger. Conversely, the first angle 172 may be relatively smaller when the dimension 133 of the apertures 110 is smaller. In the configuration of FIGS. 4A-4C, the first angle 172 may be greater than or equal to about 20 degrees to less than or equal to about 60 degrees (e.g., optionally greater than or equal to about 25 degrees, optionally greater than or equal to about 30 degrees, optionally greater than or equal to about 35 degrees, optionally greater than or equal to about 40 degrees, optionally greater than or equal to about 45 degrees, optionally greater than or equal to about 50 degrees, optionally greater than or equal to about 55 degrees). In one example, the first angle 172 may be about 30 degrees.

[0101] Each of the chamfered recesses 168 extend radially inward from side wall 154 at a second angle 170 (FIG. 4C). The second angle 170 is large enough to enable fluid at the intermediate pressure to flow through the intermediate-fluid ports 140 when the piston 74 is proximate to a bottom dead center (BDC) position (see, e.g., FIG. 5A and 8A). In other words, the second angle 170 of the piston 74 enables fluid at the intermediate pressure to flow through the intermediate-fluid ports 140 when the piston 74 is approaching the BDC position. The second angle 170 may be tailored to meet the desired fluid flow characteristics of the fluid at the intermediate pressure. The second angle 170 may be greater than or equal to about 10 degrees to less than or equal to about 45 degrees (e.g., greater than or equal to about 15 degrees, optionally greater than or equal to about 20 degrees, optionally greater than or equal to about 25 degrees, optionally greater than or equal to about 30 degrees, optionally greater than or equal to about 35 degrees, or optionally greater than or equal to about 40 degrees). In one example, the second angle 170 may be about 25 degrees.

[0102] A dimension 175 of the side wall 154 between one of the grooves 164 and each of the chamfered recesses 168 may be greater than or equal to about 0.1 millimeters (mm) to less than or equal to about 0.5 mm. In one example, the dimension 175 may be about 0.25 mm.

[0103] With renewed reference to FIGS. 1-2 and 5-6, in operation, the working fluid is compressed in the compressor 10 from the suction pressure to the discharge pressure. The working fluid passes through the inlet port 16 and enters the compressor housing 12 in a low-pressure, gaseous form (i.e., at the suction pressure). The working fluid fills an inner volume of the compressor housing 12 and is drawn into the first and second compression mechanisms 30, 31 for compression. That is, the working fluid at the suction pressure moves into each of the cylinders 46, 48, 66, 68. The pistons 74, 75, 76, and 77 are cycled within the respective cylinders 46, 48, 66, 68 due to rotation of the crankshaft 79 relative to the compressor housing 12. During the cycling, the working fluid is compressed from the suction pressure to the discharge pressure as the pistons 74, 75, 76, 77 are moved within and relative to each cylinder 46, 48, 66, 68.

[0104] Working fluid enters the cylinders 46, 48, 66, 68 during a suction stroke of each of the pistons 74, 75, 76, 77 when the piston 74, 75, 76, 77 is moving from a top dead center (TDC) position (see, e.g., the position of piston 74 in FIG. 5B) to the BDC position (see, e.g., the position of piston 74 in FIG. 5A). When the piston 74, 75, 76, 77 is at the TDC position, the crankshaft 79 rotates approximately 180 degrees to move the particular piston 74, 75, 76, 77 into the BDC position, thereby causing the piston 74, 75, 76, 77 to move from a location proximate to a top portion of the particular cylinder 46, 48, 66, 68 (FIG. 5B) to a location proximate to a bottom portion of the cylinder 46, 48, 66, 68 (FIG. 5A). When the pistons 74, 75, 76, 77 are moved toward the BDC position from the TDC position, the pressure within the particular cylinder 46, 48, 66, 68 becomes lower than suction pressure, which causes the working fluid at the suction pressure to be drawn into the cylinder 46, 48, 66, 68.

[0105] The pistons 74, 75, 76, 77 reciprocate linearly as the crankshaft 79 is driven by a motor (not shown). Specifically, the first piston 74 and the second piston 75 of the first compression mechanism 30 move in alternating directions relative to each other during operation of the compressor 10. The third piston 76 and the fourth piston 77 of the second compression mechanism 31 likewise move in alternating directions during operation.

[0106] With reference to FIGS. 5A-5B, the movement of the first piston 74 between the BDC (FIG. 5A) and the TDC (FIG. 5B) positions is shown. The movement of second, third, and fourth pistons 75, 76, and 77 are the same as the movement of first piston 74. As the crankshaft 79 rotates, the first piston 74 is driven in an upward direction, compressing the working fluid disposed within the first cylinder 46. When the first piston 74 travels to the TDC position (FIG. 5B), the effective volume of the first cylinder 46 is reduced, thereby compressing the working fluid disposed within the first cylinder 46. The compressed working fluid is elevated from suction pressure to discharge pressure. After being compressed to the discharge pressure, the fluid may exit the first cylinder 46 and enter a discharge chamber (not shown).

[0107] Following compression, the first piston 74 returns to BDC and working fluid at the suction pressure is once again drawn into the first cylinder 46. While the pistons 74, 75, 76, 77 are concurrently driven by the crankshaft 79, the first and second pistons 74, 75 and the third and fourth pistons 76, 77, are out of phase with one another. In this way, when one of the first and second pistons 74, 75 is in the TDC position, the other of the first and second pistons 74, 75 is in the BDC position. When one of the third and fourth pistons 76, 77 is in the TDC position, the other of the third and forth pistons 76, 77 is in the BDC position. Further when one of the first and second or third and fourth pistons 74, 75, 76, 77 is moving from the BDC position to the TDC position, the other of the first and second or third and fourth pistons 74, 75, 76, 77 is moving from the TDC position to the BDC position. Accordingly, for each pair of pistons (e.g., first and second piston 74, 75 an/or third and fourth piston 76, 77), one of the pistons 74, 75, 76, 77 is increasing cylinder volume to facilitate drawing working fluid into the cylinders 46, 48, 66, 68 at the suction pressure while the other is compressing the working fluid to the discharge pressure in the other of the cylinders 46, 48, 66, 68.

[0108] Referring back to FIGS. 1-2, after compression, the working fluid at the discharge pressure is expelled from the compressor housing 12 through the discharge port 18. The fluid at discharge pressure may then be communicated to a heat exchanger of an external refrigeration system (not shown). For example, the working fluid at the discharge pressure may be communicated to a condenser (not shown) of a refrigeration system.

[0109] Compressor 10 further includes a fluid injection system 180 that is configured to selectively inject fluid at an intermediate pressure (the intermediate fluid) into the compressor 10 to increase performance and/or efficiency of compressor 10. Specifically, the fluid injection system 180 is configured to selectively inject fluid at the intermediate pressure into the first and second compression mechanisms 30, 31. The compressor 10 including the fluid injection system 180 may improve efficiency of the refrigeration system during operation. A compressor including the fluid injection system 180 may require less work to increase pressure of fluid at the intermediate pressure to the discharge pressure as compared to a refrigeration system that is free of a fluid injection system (e.g., a compressor that throttles fluid at the intermediate pressure into the fluid at the suction pressure).

[0110] The fluid injection system 180 includes the housing cover 14 defining an intermediate-fluid port 200, a first intermediate-fluid passage 202 in fluid communication with the intermediate-fluid port 200 and the first storage plenum 44, a second intermediate-fluid passage 203 in fluid communication with the intermediate-fluid port 200 and the second storage plenum 58. The fluid injection system 180 cooperates with the sleeve assembly 69 and the pistons 74, 75, 76, 77 of each of the respective cylinders 46, 48, 66, 68 to selectively permit fluid at an intermediate pressure to enter the cylinders 46, 48, 66, 68 during operation of the compressor 10. The fluid injection system 180 may receive the intermediate fluid from an external source 205 (FIG. 1) such as a flash tank or heat exchanger. The intermediate pressure of the intermediate fluid is higher than the suction pressure and lower than the discharge pressure. Selectively injecting intermediate fluid into the compressor 10 may reduce the work required by compressor 10 to increase the working fluid pressure from the suction pressure to the discharge pressure. As a result, the energy consumed by the compressor 10 is reduced, thereby increasing compressor capacity and efficiency.

[0111] As best shown FIG. 6 and FIGS. 7A-7G, the housing cover 14 may define the intermediate-fluid port 200. Intermediate fluid enters the compressor housing 12 at the intermediate-fluid port 200, travels through the first intermediate-fluid passage 202 and the second intermediate-fluid passage 203 in fluid communication with the intermediate-fluid port 200 and is stored in the first and second storage plenums 44, 58 of the first compression mechanism 30 and the second compression mechanism 31, respectively. In this way, the housing cover 14 cooperates with the intermediate-fluid passages 202, 203, the first storage plenum 44 and the second storage plenum 58 to fluidly connect the external source of intermediate fluid to the cylinders 46, 48, 66, 48 of first and second compression mechanisms 30, 31. The intermediate fluid flows from the intermediate-fluid port 200 through the first and second fluid inlets 36, 56 of the first storage plenum 44 and the second storage plenum 58, respectively, due to a pressure difference between the suction pressure of the compressor housing 12 and the intermediate pressure of the intermediate fluid. Pistons 74, 75, 76, 77 selectively restrict flow of the intermediate fluid into the respective cylinders 46, 48, 66, 68 through the plurality of intermediate-fluid ports 140.

[0112] With reference to FIGS. 7A-7G, the housing cover 14 including the intermediate-fluid port 200 is shown. The housing cover includes a body 204, a first surface 206 (FIG. 7A) and an opposite second surface 208 (FIG. 7D). As shown in the configuration of FIGS. 7A-7G, the body 204 is generally circular in shape, although other shapes and configurations are possible. The body defines an outer diameter 209 and an inner diameter 210 positioned radially inward from the outer diameter 209. As shown in FIG. 7D, a third or cavity surface 212 protrudes axially outward from second surface along at least a portion of inner diameter 210. In the configuration of FIGS. 7A-7G, the cavity surface 212 is integrally formed with housing cover 14. However, in alternate embodiments, cavity surface 212 may be formed of one or more distinct components fixed to housing cover 14 (e.g., by welding, adhesive, fasteners, etc.).

[0113] At least one cavity 214 is defined between the cavity surface 212 and the second surface 208. The cavity 214 is in fluid communication with the intermediate-fluid port 200. That is, intermediate fluid enters the compressor 10 through intermediate-fluid port 200 and flows into cavity 214. One or more protrusions 216 (FIG. 7B) may extend from the second surface 208 between the second surface 208 and the cavity surface 212 to form one or more sub-cavities in fluid communication with intermediate-fluid port 200.

[0114] The body 204 defines a bore 220 extending therethrough between the first surface 206 and the cavity surface 212. A portion 222 of the bore 220 projects axially from the cavity surface 212. The portion 222 of the bore 220 is positioned within the compressor housing 12 and is configured to engage the crankshaft 79 (e.g., via a snap-fit) (i.e., at least a portion of the crankshaft 79 is received in the portion 222 of the bore 220).

[0115] A first plurality of apertures 224 are positioned about the perimeter of the body 204 between the outer diameter 209 and the inner diameter 210. The first plurality of apertures 224 extend between the first surface 206 and the second surface 208. The first plurality of apertures 224 are configured to receive a plurality of fasteners 225 (FIG. 1) (e.g., nuts, bolts, screws, studs, etc.) therethrough to fix the housing cover 14 to the compressor housing 12.

[0116] The body 204 may define a second plurality of apertures 226 positioned between the outer diameter 209 and the inner diameter 210. The second plurality of apertures 226 may only partially extend through the body 204. For example, the second plurality of apertures 226 may be defined in the second surface 208 and extend axially into body 204 to a depth 232 (FIG. 7G). The depth 232 may be less than a dimension or thickness 230 (FIG. 7G) of the body 204 between the first surface 206 and the second surface 208. Each of the second plurality of apertures 226 is connected to a channel 234 that extends radially inward from the respective second plurality of apertures 226 to the inner diameter 210. Each of the channels 234 may have a length 236 and a diameter 238 (FIG. 7G). In the configuration of FIGS. 7A-7G, the diameter 238 is less than the length 236, although other shapes and configurations are possible. Each of the channels 234 includes an intermediate-fluid inlet 240 proximate to the inner diameter 210 and an intermediate-fluid outlet 242 proximate to the second surface 208 (FIGS. 7B, and 7F-7G).

[0117] With renewed reference to FIG. 6, the plurality of channels 234 are fluidly connected to the cavity 214 and the intermediate-fluid passages 202, 203. In other words, the intermediate-fluid passages 202, 203 are in fluid communication with the cavity 214 via the plurality of channels 234. The second plurality of apertures 126 are positioned to align with the intermediate-fluid passages 202. Specifically, the second plurality of apertures 126 includes a first aperture in fluid communication with the first intermediate-fluid passage 202 and a second aperture in fluid-communication with the second intermediate-fluid passage 203. Intermediate fluid enters the housing cover 14 at the intermediate-fluid port 200, flows through the cavity 214, flows through the channels 234, the second plurality of apertures 126, and through the intermediate-fluid passages 202, 203 into the respective first and second storage plenums 44, 58. In this way, one source of fluid at the intermediate pressure is supplied to both the first compression mechanism 30 and the second compression mechanism 31.

[0118] Movement of pistons 74, 75, 76, 77 within respective cylinders 46, 48, 66, 68, selectively permits fluid communication of the fluid at the intermediate pressure into the cylinders 46, 48, 66, 68 through the intermediate-fluid ports 140 of the sleeve assembly 69. FIGS. 8A and 8B show a schematic of the fluid flow paths A and B of the fluid at the intermediate pressure when the piston 74 is moving towards the BDC position (FIG. 8A) and towards the TDC position (FIG. 8B). When the piston 74 is moving towards the BDC position, the pressure of the working fluid in the cylinder 46 is initially at or near the suction pressure, which is a lower pressure than the intermediate pressure. Fluid at the intermediate pressure enters the cylinder 46 when the piston 74 is approaching the BDC position due to the pressure differential between the working fluid in the cylinder 46 and the intermediate fluid in the first storage plenum 44. Approaching or at the BDC position, the seal 176 of the piston 74 is at least partially below the plurality of intermediate-fluid ports 140, enabling intermediate fluid in the first storage plenum 44 to pass through the plurality of intermediate-fluid ports 140 (see, e.g., fluid path A of the intermediate fluid shown in FIG. 8A). The second angle 170 of each of the recessed chamfers 168 provides an opening to permit the intermediate fluid to flow from the respective intermediate-fluid port 140 into the volume of the cylinder 46.

[0119] When the intermediate fluid enters the cylinder 46 via the plurality of intermediate-fluid ports 140, the pressure within the cylinder 46 increases, thereby reducing the work required to raise the pressure of the intermediate fluid within the cylinder 46 to the discharge pressure. Initially, the pressure differential between the working fluid in the cylinder 46 and the intermediate fluid in the first storage plenum 44 is substantial, resulting in a rapidly accelerating fluid flow of the intermediate fluid into the cylinder 46 along fluid path A. As the pressure of the fluid in the cylinder 46 increases, a velocity of the intermediate fluid along path A decreases. When the pressure of working fluid in the cylinder 46 approaches the pressure of the intermediate fluid in the first fluid storage plenum 44, the velocity of the intermediate fluid along path A will continue to decrease to approach zero.

[0120] When the pressure of the working fluid in the cylinder 46 is greater than the pressure of the intermediate fluid in the first storage plenum 44, the flow of the fluid through the plurality of intermediate-fluid ports 140 is reversed (see, e.g., fluid path B of the intermediate fluid shown in FIG. 8B). Because the reversed fluid path B at least partially intersects fluid path A, the backflow of working fluid from the cylinder 46 to the first storage plenum 44 is reduced or inhibited. This thereby reduces the loss of working fluid mass in compressor 10 as compared to a compressor that is free from the sleeve assembly 69 and fluid injection system 180.

[0121] As the piston 74 moves towards the TDC position, the seal 176 of the piston 74 blocks the intermediate-fluid ports 140, thus preventing intermediate fluid from flowing into the cylinder 46 and backflowing into the first fluid storage plenum 44. The seal 142 (FIGS. 3A-3C and 5A-5B) of the sleeve assembly 69 also cooperates to reduce or prevent the intermediate fluid from entering the cylinder 46 beneath the piston 74.

[0122] Accordingly, the fluid injection system 180 improves the efficiency of compressor 10. By providing fluid at an intermediate pressure to the first and second compression mechanisms 30, 31, less work is required to compress working fluid from the suction pressure to the discharge pressure. Additionally, less working fluid mass is lost during operation of the compressor 10. Intermediate fluid is routed from an external source to both the first and second compression mechanisms 30, 31 via a singular intermediate-fluid port 200.

[0123] With reference to FIGS. 9-11, a reciprocating compressor assembly 300 (the compressor 300) is provided. The compressor 300 may be the same as or similar to the compressor 10 of FIGS. 1-8, except as otherwise described below. The compressor 300 may include a compressor housing 312, a housing cover 314, an end cap 315, an inlet port 316, one or more discharge ports 318, and an intermediate-fluid port 321. The compressor 300 may also include a valve 320 in selective fluid communication with the intermediate-fluid port 321.

[0124] The compressor 300 may include a first cylinder housing or deck 322 (FIG. 11) and a second cylinder housing or deck 324 positioned within the compressor housing 312. The decks 322, 324 may be the same as the decks 22, 24 of FIGS. 1-2. A first storage plenum 323 (FIG. 11) and a first cylinder and a second cylinder (neither shown) (see, e.g., first cylinder 46 and second cylinder 48 of FIG. 2) are defined in the compressor housing 312 adjacent to the first deck 322. A second storage plenum 325 (FIG. 11) a third and fourth cylinder (neither shown) (see, e.g., third cylinder 66 and fourth cylinder 68 of FIG. 2) are defined in the cylinder housing 312 adjacent to the second deck 324. A first cylinder head 350 and a second cylinder head 352 are fixed to the first deck 322 and the second deck 324, respectively. Each of the first cylinder head 350 and the second cylinder head 352 may cooperate with one or more cylinder head gaskets, valve plates, deck plates, and one or more deck gaskets (not shown, see, e.g., cylinder head gaskets 34, valve plate 36, deck plate 38 and one or more deck gaskets 40 of FIG. 2) to seal the compressor housing 312 from outside contaminants. To

[0125] A sleeve assembly 370 is received in each of the cylinders. The sleeve assembly 370 includes a sleeve 372 and a collar 374. The sleeve assembly 370 may be the same as the sleeve assembly 69 of FIGS. 1-2 and 3A-3E.

[0126] The compressor housing 312 and decks 322, 324 contain a first compression mechanism 381 in the first deck 322 and a second compression mechanism 382 in the second deck 324. The first compression mechanism 381 and the second compression mechanism 382 selectively compresses a fluid from a suction pressure to a discharge pressure.

[0127] A first and second piston 384, 385, of the first compression mechanism 381 and a third and fourth piston 386, 387 of the second compression mechanism 382 are located within the compressor housing 312 and are reciprocally movable in linear directions by respective connecting rods 388. The first piston 384 is seated in the sleeve assembly 370 of the first cylinder, the second piston 385 is seated in the sleeve assembly 370 of the second cylinder, the third piston 386 is seated in the sleeve assembly 370 of the third cylinder, and the fourth piston 387 is seated in the sleeve assembly 370 of the fourth cylinder. The connecting rods 388 are disposed between the respective pistons 384, 385, 386, 387 and a crankshaft 392 to allow a rotational force applied to the crankshaft 392 to be transmitted to pistons 384, 385, 386, 387.

[0128] As best shown in FIG. 11, compressor 300 further includes a fluid injection system 400 that is configured to selectively inject intermediate fluid into the compressor 300 to increase performance and/or efficiency of compressor 300 during operation. Fluid injection system 400 includes the valve 320, the intermediate-fluid port 321, a first fluid intermediate-fluid passage 394 in fluid communication with the intermediate-fluid port 321 and the first fluid storage plenum 323, and a second intermediate-fluid passage 395 in fluid communication with the intermediate-fluid port 321 and the second fluid storage plenum 325. The fluid injection system 400 cooperates with the sleeve assembly 370 and the pistons 384, 385, 386, 387 of each of the respective first, second, third, and fourth cylinders to selectively permit fluid at an intermediate pressure to enter the cylinders during operation of the compressor 300. Similar to the fluid injection system 180 of FIGS. 1-8, the fluid injection system 400 may receive intermediate fluid from an external source 402 such as a flash tank or heat exchanger. The intermediate-fluid port 321 receives intermediate fluid from the external source (e.g., via the intermediate-fluid valve 320). The intermediate-fluid port 321 is fluidly connected to the first storage plenum 323 of the first cylinder housing 322 and the second storage plenum 325 of the second cylinder housing 324. Specifically, the intermediate-fluid port 320 is fluidly connected to the first storage plenum 323 via the first intermediate-fluid passage 394 and the second storage plenum 325 via the second intermediate-fluid passage 395. In this way, as shown in fluid path A of FIG. 12, intermediate fluid enters the compressor housing 312 at the intermediate-fluid valve 320, travels through the intermediate-fluid port 321, through the intermediate-fluid passages 394, 395, and is stored in the respective first and second vapor storage plenums 323, 325 of the first and second compression mechanisms 381, 382, respectively.

[0129] During operation of the compressor 300, the pistons 384, 385, 386, 387 cooperate with the sleeve assembly 370 to selectively restrict flow of the intermediate fluid into the respective cylinders. When the intermediate fluid enters the cylinders, the work required to compress the working fluid from the suction pressure to the discharge pressure is reduced.

[0130] 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.