Patent Publication Number: US-10323639-B2

Title: Variable volume ratio compressor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 14/663,073 filed on Mar. 19, 2015. The entire disclosure of the above application is incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to a variable volume ratio compressor. 
     BACKGROUND 
     This section provides background information related to the present disclosure and is not necessarily prior art. 
     A climate-control system such as, for example, a heat-pump system, a refrigeration system, or an air conditioning system, may include a fluid circuit having an outdoor heat exchanger, an indoor heat exchanger, an expansion device disposed between the indoor and outdoor heat exchangers, and one or more compressors circulating a working fluid (e.g., refrigerant or carbon dioxide) between the indoor and outdoor heat exchangers. Efficient and reliable operation of the one or more compressors is desirable to ensure that the climate-control system in which the one or more compressors are installed is capable of effectively and efficiently providing a cooling and/or heating effect on demand. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     In one form, the present disclosure provides a compressor that may include a shell, first and second scroll members, a partition plate, a bypass valve retainer and a bypass valve member. The shell may define a discharge-pressure region and a suction-pressure region. The first scroll member is disposed within the shell and includes a first end plate and a first spiral wrap extending from a first side of the first end plate. The first end plate may include a discharge passage, a first bypass passage and a second bypass passage extending through the first side and a second side of the first end plate. The second scroll member includes a second spiral wrap cooperating with the first spiral wrap to define first and second fluid pockets therebetween. The first and second fluid pockets may be in communication with the first and second bypass passages, respectively. The partition plate is disposed within the shell and separates the discharge-pressure region from the suction-pressure region. The partition plate may include a first opening in communication with the discharge-pressure region. The bypass valve retainer may be attached to the partition plate and may include a second opening in communication with the first opening, the discharge passage and the discharge-pressure region. The bypass valve member may be disposed around the discharge passage within the first opening and may be movable between a first position in which the bypass valve member contacts the first end plate and restricts fluid flow through at least one of the first and second bypass passages and a second position in which the bypass valve member allows fluid flow through the at least one of the first and second bypass passages and through the second opening. 
     In some configurations, the compressor includes a spring member disposed between the bypass valve retainer and the bypass valve member and biasing the bypass valve member toward the first position. 
     In some configurations, the spring member is integral with the bypass valve member. 
     In some configurations, the compressor includes a discharge valve member movable relative to the bypass valve retainer between a first position in which the discharge valve member contacts the bypass valve retainer and restricts communication between the second opening and the discharge-pressure region and a second position in which the discharge valve member is spaced apart from the bypass valve retainer and allows communication between the second opening and the discharge-pressure region. 
     In some configurations, the compressor includes a discharge valve retainer attached to the bypass valve retainer and defining a cavity in which the discharge valve member is movable between the first and second positions. The cavity may be in communication with the discharge-pressure region. 
     In some configurations, the discharge valve retainer, the bypass valve retainer and the partition plate are separate components that are fixed relative to each other. 
     In some configurations, the first end plate cooperates with the partition plate to define an annular biasing chamber therebetween that extends around the discharge passage and the first and second bypass passages. The first end plate may include a bleed hole extending therethrough and in communication with the biasing chamber. 
     In some configurations, the compressor includes first and second seal members sealing contacting the first end plate and the partition plate and defining the biasing chamber. 
     In some configurations, the first end plate includes first and second annular grooves. The first and second seal members may each include an L-shaped cross section having a first leg and a second leg. The first legs of the first and second seal members may be received in the first and second annular grooves, respectively. The second legs of the first and second seal members may extend parallel to the partition plate and sealingly contact the first end plate and the partition plate. 
     In another form, the present disclosure provides a compressor that may include a shell, first and second scroll members, a partition plate and a bypass valve member. The shell may define a discharge-pressure region and a suction-pressure region. The first scroll member is disposed within the shell and includes a first end plate and a first spiral wrap extending from a first side of the first end plate. The first end plate may include a discharge passage, a first bypass passage and a second bypass passage extending through the first side and a second side of the first end plate. The second scroll member includes a second spiral wrap cooperating with the first spiral wrap to define first and second fluid pockets therebetween. The first and second fluid pockets may be in communication with the first and second bypass passages, respectively. The partition plate is disposed within the shell and separates the discharge-pressure region from the suction-pressure region. The partition plate may include an opening in communication with the discharge-pressure region. The first scroll member may include a hub through which the discharge passage may extend. The bypass valve member may be disposed around the hub and may be movable between a first position in which the bypass valve member restricts fluid flow through at least one of the first and second bypass passages and a second position in which the bypass valve member allows fluid flow through the at least one of the first and second bypass passages and into the discharge-pressure region. 
     In some configurations, the compressor includes a bypass valve retainer and a spring member. The bypass valve retainer may be attached to an outer diametrical surface of the hub. The spring member may be disposed between the bypass valve retainer and the bypass valve member and may bias the bypass valve member toward the first position. 
     In some configurations, the spring member is integral with the bypass valve member. 
     In some configurations, the compressor includes a retaining ring partially received in an annular groove formed in the hub and extending radially outward from the hub. The spring member may bias the bypass valve retainer into contact with the retaining ring. 
     In some configurations, the compressor includes a discharge valve member movable relative to the hub between a first position in which the discharge valve member contacts the hub and restricts communication between the discharge passage and the discharge-pressure region and a second position in which the discharge valve member is spaced apart from the hub and allows communication between the discharge passage and the discharge-pressure region. 
     In some configurations, the hub extends at least partially through the opening in the partition plate and includes a diametrical surface cooperating with a diametrical surface of the opening to define an annular chamber therebetween. The annular chamber may receive fluid from the first and second bypass passages when the bypass valve member is in the second position. 
     In some configurations, the bypass valve retainer is disposed within the annular chamber. 
     In some configurations, the compressor includes a discharge valve retainer attached to the partition plate and defining a discharge cavity in communication with the discharge-pressure region. A discharge valve member may be disposed within the discharge cavity and may be movable therein between a first position in which the discharge valve member restricts communication between the discharge passage and the discharge cavity and restricts communication between the annular chamber and the discharge cavity and a second position in which the discharge valve member allows communication between the discharge passage and the discharge cavity and allows communication between the annular chamber and the discharge cavity. 
     In some configurations, the discharge valve retainer includes a diametrical surface defining the discharge cavity and including a plurality of openings providing communication between the discharge-pressure region and the discharge cavity. 
     In some configurations, the first end plate cooperates with the partition plate to define an annular biasing chamber therebetween that extends around the discharge passage and the first and second bypass passages. The first end plate may include a bleed hole extending therethrough and communicating with the biasing chamber. 
     In some configurations, the compressor includes first and second seal members sealing contacting the first end plate and the partition plate and defining the biasing chamber. 
     In some configurations, the first end plate includes first and second annular grooves. The first and second seal members may each include an L-shaped cross section having a first leg and a second leg. The first legs of the first and second seal members may be received in the first and second annular grooves, respectively. The second legs of the first and second seal members may extend parallel to the partition plate and sealingly contact the first end plate and the partition plate. 
     In another form, the present disclosure provides a compressor that may include a shell, first and second scroll members, a partition plate, a valve housing and a bypass valve member. The shell may define a discharge-pressure region and a suction-pressure region. The first scroll member is disposed within the shell and includes a first end plate and a first spiral wrap extending from a first side of the first end plate. The first end plate may include a discharge recess, a discharge passage, a first bypass passage and a second bypass passage. The discharge recess may be in communication with the discharge passage and the discharge-pressure region. The first and second bypass passages may extending through the first side and a second side of the first end plate. The second scroll member includes a second spiral wrap cooperating with the first spiral wrap to define first and second fluid pockets therebetween. The first and second fluid pockets may be in communication with the first and second bypass passages, respectively. The partition plate is disposed within the shell and separates the discharge-pressure region from the suction-pressure region. The valve housing may extend at least partially through the partition plate and may be partially received in the discharge recess. The valve housing may include a first passage extending therethrough and communicating with the discharge-pressure region and the discharge recess. The bypass valve member may be disposed between the first end plate and a flange of the valve housing and may be movable between a first position in which the bypass valve member restricts fluid flow through at least one of the first and second bypass passages and a second position in which the bypass valve member allows fluid flow through the at least one of the first and second bypass passages and into the first passage in the valve housing. 
     In some configurations, the valve housing includes a second passage having a first portion with a first diameter and a second portion with a second diameter that is larger than the first diameter to form a first annular ledge. 
     In some configurations, the compressor includes a discharge valve disposed within the discharge recess and including a stem portion that is slidably received in the second portion of the second passage of the valve housing. The discharge valve may be movable relative to the valve housing and the first end plate between a first position in which the discharge valve contacts a second annular ledge defining the discharge recess and restricts communication between the discharge passage and the first passage and a second position in which the discharge valve is spaced apart from the second annular ledge and allows communication between the discharge passage and the first passage. 
     In some configurations, the first portion of the second passage in the valve housing allows high-pressure fluid in the discharge-pressure region to bias the discharge valve toward the first position. 
     In some configurations, the compressor includes a floating seal slidably received in an annular recess formed in the first end plate. The floating seal may cooperate with the first end plate to define a biasing chamber therebetween. The first end plate may include a bleed hole extending therethrough and communicating with the biasing chamber. The floating seal contacts the valve housing and defines an annular chamber in which the bypass valve member is disposed. 
     In some configurations, the first and second bypass passages are disposed between the discharge recess and the annular recess. 
     In some configurations, the compressor includes a retaining ring engaging the valve housing and disposed within the discharge recess. The retaining ring may extend radially between the valve housing and a diametrical surface of the discharge recess. 
     In some configurations, the bypass valve member is an annular member that slidably engages the valve housing. 
     In some configurations, the compressor includes a spring member disposed between the valve housing and the bypass valve member and biasing the bypass valve member toward the first position. 
     In some configurations, the spring member is integral with the bypass valve member. 
     In another form, the present disclosure provides a compressor that may include a shell, first and second scroll members, a partition plate and first and second bypass valve members. The shell may define a discharge-pressure region and a suction-pressure region. The first scroll member is disposed within the shell and includes a first end plate and a first spiral wrap extending from a first side of the first end plate. The first end plate may include a discharge passage, a first bypass passage and a second bypass passage extending through the first side and a second side of the first end plate. The second scroll member includes a second spiral wrap cooperating with the first spiral wrap to define first and second fluid pockets therebetween. The first and second fluid pockets may be in communication with the first and second bypass passages, respectively. The partition plate is disposed within the shell and separates the discharge-pressure region from the suction-pressure region. The partition plate may include first and second openings in communication with the first and second bypass passages. The first and second bypass valve members may be movable between first positions restricting fluid flow through the first and second openings and second positions allowing fluid flow through the first and second openings. 
     In some configurations, the compressor includes a first annular seal fluidly coupling the first bypass passage and the first opening and a second annular seal fluidly coupling the second bypass passage and the second opening. 
     In some configurations, the partition plate and the first end plate cooperate to define a biasing chamber therebetween, and wherein the first and second annular seals extend axially through the biasing chamber. 
     In some configurations, the first and second bypass valve members are disposed within the discharge-pressure region and mounted to the partition plate. 
     In some configurations, the first and second bypass valve members are reed valves that flex between the open and closed positions. 
     In some configurations, the compressor includes first and second rigid valve retainers that clamp the first and second bypass valve members against the partition plate and define a range of flexing movement of the first and second bypass valve members. 
     In some configurations, the compressor includes third and fourth annular seals that contact the partition plate and the end plate and cooperate to define the biasing chamber therebetween. 
     In some configurations, the first end plate includes first and second annular grooves. The third and fourth annular seals may each include an L-shaped cross section having a first leg and a second leg. The first legs of the third and fourth annular seals may be received in the first and second annular grooves, respectively. The second legs of the third and fourth annular seals may extend parallel to the partition plate and sealingly contacting the first end plate and the partition plate. 
     In some configurations, the first end plate includes a hub that extends axially through a third opening in the partition plate between the first and second openings. 
     In some configurations, the discharge passage extends through the hub. 
     In some configurations, the compressor includes a discharge valve disposed within the discharge-pressure region and movable between a first position restricting communication between the discharge passage and the discharge-pressure region and a second position allowing communication between the discharge passage and the discharge-pressure region. 
     In some configurations, the discharge valve contacts the hub in the first position. 
     In some configurations, the compressor includes a discharge valve retainer attached to the partition plate and defining a discharge cavity in communication with the discharge-pressure region. The discharge valve may be disposed within the discharge cavity and may be movable therein between the first and second positions. The discharge valve retainer may include a diametrical surface defining the discharge cavity and including a plurality of openings providing communication between the discharge-pressure region and the discharge cavity. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       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. 
         FIG. 1  is a cross-sectional view of a compressor having a variable volume ratio valve system according to the principles of the present disclosure; 
         FIG. 2  is a partial cross-sectional view of the compressor of  FIG. 1  with a bypass valve in a closed position; 
         FIG. 3  is a partial cross-sectional view of the compressor of  FIG. 1  with a bypass valve in an open position; 
         FIG. 4  is a partial cross-sectional view of another compressor of with a bypass valve in a closed position; 
         FIG. 5  is a partial cross-sectional view of the compressor of  FIG. 4  with a bypass valve in an open position; 
         FIG. 6  is a partial cross-sectional view of another compressor of with a bypass valve in a closed position; 
         FIG. 7  is a partial cross-sectional view of the compressor of  FIG. 6  with a bypass valve in an open position; 
         FIG. 8  is a partial cross-sectional view of another compressor of with a bypass valve in an open position; 
         FIG. 9  is a partial cross-sectional view of the compressor of  FIG. 8  with a bypass valve in a closed position; 
         FIG. 10  is a perspective view of a valve and spring assembly according to the principles of the present disclosure; 
         FIG. 11  is a perspective view of another valve and spring assembly according to the principles of the present disclosure; and 
         FIG. 12  is a perspective view of yet another valve and spring assembly according to the principles of the present disclosure. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
     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. 
     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. 
     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. 
     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. 
     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&#39;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. 
     With reference to  FIGS. 1-3 , a 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 , and a variable volume ratio assembly  24 . 
     The shell assembly  12  may house the motor assembly  18 , the bearing housing assembly  20 , the compression mechanism  22 , and the variable volume ratio assembly  24 . The shell assembly  12  may include a generally cylindrical shell  34 , an end cap  36 , a transversely extending partition plate  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 plate  37  may define a discharge chamber  42  (i.e., a discharge-pressure region) therebetween that receives compressed working fluid from the compression mechanism  22 . The partition plate  37  may include an opening  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 . 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  (i.e., a suction-pressure region). The partition plate  37  separates the discharge chamber  42  from the suction chamber  43 . 
     The motor assembly  18  may include a motor stator  44 , a rotor  46 , and a driveshaft  48 . The stator  44  may be press fit into the shell  34 . The driveshaft  48  may be rotatably driven by the rotor  46  and supported by the bearing housing assembly  20 . The driveshaft  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 driveshaft  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 main bearing housing  54  may include an annular flat thrust bearing surface  58  that supports the compression mechanism  22  thereon. 
     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. 
     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 . The spiral wraps  66 ,  80  cooperate to form a plurality of fluid pockets  83  therebetween. A second side  84  of the end plate  78  may include a hub  86  and inner and outer annular grooves  88 ,  90  ( FIGS. 2 and 3 ). The hub  86  can be generally axially aligned with the rotational axis of the driveshaft  48 . The annular grooves  88 ,  90  may be substantially concentric with each other and the hub  86  and may surround the hub  86 . 
     Inner and outer annular seals  91 ,  92  may be partially received in the annular grooves  88 ,  90 , respectively, and may sealingly contact the partition plate  37  and the end plate  78  to form an annular biasing chamber  97  therebetween. The annular seals  91 ,  92  may have generally L-shaped cross sections having first and second legs  93 ,  94  ( FIGS. 2 and 3 ). The first legs  93  may be received in the corresponding annular grooves  88 ,  90 , and the second legs  94  may extend generally parallel to the partition plate  37  and the end plate  78  and sealingly contact the partition plate  37  and the end plate  78 . 
     As shown in  FIGS. 2 and 3 , the non-orbiting scroll  62  may also include a discharge passage  95 , first and second bypass passages  96 ,  98  and a bleed hole  100  that extend through the end plate  78 . The discharge passage  95  may extend axially through the hub  86  and may be in fluid communication with a central fluid pocket  83  defined by the spiral wraps  66 ,  80 . The first and second bypass passages  96 ,  98  are variable volume ratio passages disposed radially outward relative to the discharge passage  95  and are in fluid communication with respective ones of the fluid pockets  83 . The first and second bypass passages  96 ,  98  may extend through the hub  86  and may be disposed radially between the discharge passage  95  and the inner annular groove  88 . The bleed hole  100  may be disposed radially between the inner and outer annular grooves  88 ,  90  and may be in communication with an intermediate-pressure (higher than suction pressure and less than discharge pressure) fluid pocket  83 . The bleed hole  100  is in fluid communication with the annular biasing chamber  97  and provides intermediate-pressure working fluid to the annular biasing chamber  97 . In this manner, the working fluid in the annular biasing chamber  97  biases the non-orbiting scroll  62  in an axial direction (i.e., in a direction parallel to the axis of rotation of the driveshaft  48 ) into engagement with the orbiting scroll  60 . 
     As shown in  FIGS. 2 and 3 , the variable volume ratio assembly  24  may include a bypass valve retainer  102 , a bypass valve member  104 , a spring member  106 , a discharge valve retainer  108  and a discharge valve member  110 . The bypass valve retainer  102  may be fixedly attached to the partition plate  37  and may be an annular member having a first side  112  with a first annular ridge  114  extending therefrom and a second side  116  opposite the first side  112  with a second ridge  118  extending therefrom. The first annular ridge  114  may extend into the opening  39  of the partition plate  37  and an outer diametrical surface  120  of the first annular ridge  114  may engage an inner diametrical surface  122  of the opening  39  by a press-fit, for example. The second annular ridge  118  can be concentric with the first annular ridge  114  and may define an opening  124  in fluid communication with the discharge passage  95 , the opening  39  and the discharge chamber  42 . 
     The bypass valve member  104  can be a generally flat, annular member and may be disposed within the opening  39  of the partition plate  37  between the hub  86  of the non-orbiting scroll  62  and bypass valve retainer  102 . The bypass valve member  104  may surround the discharge passage  95  and may be movable between a closed position ( FIG. 2 ) and an open position ( FIG. 3 ). In the closed position, the bypass valve member  104  is in contact with the hub  86  and restricts or prevents fluid flow through the first and second bypass passages  96 ,  98  (i.e., restricting or preventing fluid communication between the bypass passages  96 ,  98  and the discharge chamber  42 ). In the open position, the bypass valve member  104  is spaced apart from the hub  86  and allows fluid flow through the first and second bypass passages  96 ,  98  (i.e., allowing fluid communication between the bypass passages  96 ,  98  and the discharge chamber  42 ). The spring member  106  may be disposed between and in contact with the bypass valve member  104  and the bypass valve retainer  102  such that the spring member  106  biases the bypass valve member  104  toward the closed position. 
     In some configurations, the partition plate  37  may include an annular ledge  125  that extends radially into the opening  39  of the partition plate  37 . The bypass valve member  104  may be disposed axially between the annular ledge  125  and the bypass valve retainer  102 . In this manner, the annular ledge  125  and the bypass valve retainer  102  cooperate to keep the bypass valve member  104  captive within the opening  39 . Therefore, the partition plate  37  and the variable volume ratio assembly  24  can be assembled as a unit separately from the non-orbiting scroll  62 . 
     The discharge valve retainer  108  may be fixedly attached to the bypass valve retainer  102  and may include a central hub  126  and a flange  128  extending radially outward from the central hub  126 . The central hub  126  may define a cavity  130  in fluid communication with the discharge chamber  42  via a plurality of apertures  132  that extend through inner and outer diametrical surfaces of the central hub  126 . The second annular ridge  118  of the bypass valve retainer  102  may be received in the cavity  130  and may act as a valve stop for the discharge valve member  110 . In some configurations, a tube  134  may extend through an axial end  136  of the central hub  126  and may direct a portion of the fluid in the cavity  130  directly to the discharge fitting  14 . 
     The discharge valve member  110  may be a generally flat disk and may be movably received in the cavity  130  of the discharge valve retainer  108 . The discharge valve member  110  may be movable relative to the discharge valve retainer  108  and the bypass valve retainer  102  between a closed position in which the discharge valve member  110  is seated against the second annular ridge  118  and an open position in which the discharge valve member  110  is spaced apart from the second annular ridge  118 . In the closed position, the discharge valve member  110  restricts or prevents fluid communication between the discharge chamber  42  and the opening  124  of the bypass valve retainer  102  (thereby restricting or preventing fluid communication between the discharge passage  95  and the discharge chamber  42 ). In the open position, the discharge valve member  110  allows fluid communication between the discharge chamber  42  and the opening  124  of the bypass valve retainer  102  (thereby allowing fluid communication between the discharge passage  95  and the discharge chamber  42 ). 
     During operation of the compressor  10 , working fluid in the pockets  83  between the wraps  66 ,  80  of the orbiting and non-orbiting scrolls  60 ,  62  increase in pressure as the pockets  83  move from a radially outer position (e.g., at suction pressure) toward a radially inner position (e.g., at discharge pressure). The bypass valve member  104  and spring member  106  may be configured so that the bypass valve member  104  will move into the open position when exposed to pockets  83  having working fluid at or above a predetermined pressure. The predetermined pressure can be selected to prevent the compressor  10  from over-compressing working fluid when the compressor  10  is operating under lighter load conditions, for example, such as during operation in a cooling mode of a reversible heat-pump system. A system pressure ratio of a heat-pump system in the cooling mode may be lower than the system pressure ratio of the heat-pump system in a heating mode. 
     If, for example, the compressor  10  is operating under lighter load conditions and working fluid is being compressed to a pressure equal to or greater than the predetermined pressure by the time the pockets  83  containing the working fluid reaches the first and/or second bypass passages  96 ,  98 , the bypass valve member  104  will move into the open position to allow the working fluid to flow through the bypass passages  96 ,  98 , through the openings  39 ,  124  and into the discharge chamber  42  and/or the tube  134  (after forcing the discharge valve member  110  toward the open position). In this manner, the first and second bypass passages  96 ,  98  may act as discharge passages when the bypass valve member  104  is in the open position. 
     If working fluid is not compressed to a level at least equal to the predetermined pressure by the time the pocket  83  containing the working fluid reaches the bypass passages  96 ,  98 , the bypass valve member  104  will stay closed, and the working fluid will continue to be compressed until the pocket  83  is exposed to the discharge passage  95 . Thereafter, the working fluid will force the discharge valve member  110  into the open position and the working fluid will flow into the cavity  130  and into the discharge chamber  42  and/or the tube  134 . 
     It will be appreciated that the non-orbiting scroll  62  could include one or more other bypass passages in addition to the first and second bypass passages  96 ,  98 . In other configurations, the non-orbiting scroll  62  could include only one of the bypass passages  96 ,  98 . 
     With reference to  FIGS. 4 and 5 , another compressor  210  is provided that may have similar or identical structure and functions as the compressor  10  described above, apart from exceptions described below. Like the compressor  10 , the compressor  210  may include a partition plate  237 , an orbiting scroll  260 , a non-orbiting scroll  262  and a variable volume ratio assembly  224 . The partition plate  237  may separate a discharge chamber  242  and a suction chamber (like the suction chamber  43 ). The partition plate  237  includes an opening  239  in fluid communication with the discharge chamber  242 . 
     The non-orbiting scroll  262  includes an end plate  278  and a spiral wrap  280  extending from a first side  282  of the end plate  278 . A second side  284  of the end plate  278  may include a hub  286  and inner and outer annular grooves  288 ,  290 . The hub  286  may extend axially through the opening  239  in the partition plate  237 . The hub  286  may include an outer diametrical surface  287  that cooperates with a diametrical surface  289  of the opening  239  to define an annular chamber  285  therebetween. The annular grooves  288 ,  290  may be substantially concentric with each other and the hub  286  and may surround the hub  286 . Inner and outer annular seals  291 ,  292  (similar or identical to the seals  91 ,  92 ) may be partially received in the annular grooves  288 ,  290 , respectively, and may sealingly contact the partition plate  237  and the end plate  278  to form an annular biasing chamber  297  therebetween, as described above. 
     The non-orbiting scroll  262  may also include a discharge passage  295 , first and second bypass passages  296 ,  298  and a bleed hole  300  that extend through the end plate  278 . The discharge passage  295  may extend axially through the hub  286  and may be in fluid communication with a central fluid pocket  283  defined by spiral wraps  266 ,  280  of the orbiting and non-orbiting scrolls  260 ,  262 . The first and second bypass passages  296 ,  298  are variable volume ratio passages disposed radially outward relative to the discharge passage  295  and the hub  286  and are in fluid communication with respective ones of the fluid pockets  283 . The first and second bypass passages  296 ,  298  may be disposed radially between the hub  286  and the inner annular groove  288 . The bleed hole  300  may be disposed radially between the inner and outer annular grooves  288 ,  290  and may be in communication with an intermediate-pressure (higher than suction pressure and less than discharge pressure) fluid pocket  283 . The bleed hole  300  is in fluid communication with the annular biasing chamber  297  and provides intermediate-pressure working fluid to the annular biasing chamber  297 . In this manner, the working fluid in the annular biasing chamber  297  biases the non-orbiting scroll  262  in an axial direction into engagement with the orbiting scroll  260 . 
     The variable volume ratio assembly  224  may include a bypass valve retainer  302 , a retaining ring  303 , a bypass valve member  304 , a spring member  306 , a discharge valve retainer  308  and a discharge valve member  310 . The bypass valve retainer  302  can be an annular member that receives the hub  286  (i.e., the bypass valve retainer  302  extends around the hub  286 ). In some configurations, the bypass valve retainer  302  may be press-fit onto the outer diametrical surface  287 . In some configurations, the bypass valve retainer  302  may include a generally L-shaped cross section. In some configurations, the retaining ring  303  may be partially received in an annular groove  311  formed in the outer diametrical surface  287  of the hub  286 . In some configurations, the spring member  306  may bias the bypass valve retainer  302  into contact with the retaining ring  303 . 
     The bypass valve member  304  can be a generally flat, annular member and may extend around the hub  286  and may be disposed axially between a portion of the end plate  278  and the bypass valve retainer  302 . The bypass valve member  304  may surround the discharge passage  95  and may be movable between a closed position ( FIG. 4 ) and an open position ( FIG. 5 ). In the closed position, the bypass valve member  304  is in contact with the end plate  278  and restricts or prevents fluid flow through the first and second bypass passages  296 ,  298  (i.e., restricting or preventing fluid communication between the bypass passages  296 ,  298  and the discharge chamber  242 ). In the open position, the bypass valve member  304  is spaced apart from the end plate  278  and allows fluid flow through the first and second bypass passages  296 ,  298  (i.e., allowing fluid communication between the bypass passages  296 ,  298  and the discharge chamber  242 ). The spring member  306  may be disposed between and in contact with the bypass valve member  304  and the bypass valve retainer  302  such that the spring member  306  biases the bypass valve member  304  toward the closed position. 
     The discharge valve retainer  308  and the discharge valve member  310  can have similar or identical structure and function as the discharge valve retainer  108  and the discharge valve member  110 . The discharge valve retainer  308  can be mounted directly to the partition plate  237 . As described above with respect to the discharge valve retainer  108 , the discharge valve retainer  308  may include a central hub  326  defining a cavity  330 . The hub  286  of the non-orbiting scroll  262  may extend into the cavity  330  and an axial end of the hub  286  may define a valve seat  331  for the discharge valve member  310 . That is, the discharge valve member  310  contacts the valve seat  331  when the discharge valve member  310  is in the closed position to restrict or prevent fluid communication between the discharge passage  295  and the discharge chamber  242 . In the closed position, the discharge valve member  310  may also restrict or prevent fluid communication between the annular chamber  285  and the discharge chamber  242 . 
     Operation of the variable volume ratio assembly  224  may be similar or identical to that of the variable volume ratio assembly  24  described above. That is, the bypass valve member  304  may open to prevent an over-compression condition. When working fluid is being compressed by the scrolls  260 ,  262  to a pressure equal to or greater than the predetermined pressure by the time the pockets  283  containing the working fluid reaches the first and/or second bypass passages  296 ,  298 , the bypass valve member  304  will move into the open position to discharge the working fluid to the discharge chamber  242 , as described above. 
     It will be appreciated that the non-orbiting scroll  262  could include one or more other bypass passages in addition to the first and second bypass passages  296 ,  298 . In other configurations, the non-orbiting scroll  262  could include only one of the bypass passages  296 ,  298 . 
     With reference to  FIGS. 6 and 7 , another compressor  410  is provided that may have similar or identical structure and functions as the compressors  10 ,  210  described above, apart from exceptions described below. Like the compressors  10 ,  210 , the compressor  410  may include a partition plate  437 , an orbiting scroll  460 , a non-orbiting scroll  462  and a variable volume ratio assembly  424 . The partition plate  437  may separate a discharge chamber  442  and a suction chamber  443 . The partition plate  437  includes an opening  439  through which fluid is provided to the discharge chamber  442 . 
     The non-orbiting scroll  462  may include an end plate  478  and a spiral wrap  480  extending therefrom. The end plate  478  may include a hub  486  and an annular recess  488 . The annular recess  488  may at least partially receive a floating seal assembly  490  therein. The recess  488  and the seal assembly  490  may cooperate to define an axial biasing chamber  492  therebetween. 
     The non-orbiting scroll  462  may also include a discharge recess  493 , a discharge passage  495 , first and second bypass passages  496 ,  498  and a bleed hole  500  that extend through the end plate  478 . The discharge recess  493  may extend axially through the hub  486  and may be in fluid communication with a central fluid pocket  483  (defined by the scrolls  460 ,  462 ) via the discharge passage  495 . The first and second bypass passages  496 ,  498  are variable volume ratio passages disposed radially outward relative to the discharge passage  495  and are in fluid communication with respective ones of the fluid pockets  483 . The first and second bypass passages  496 ,  498  may extend through the hub  486  and may be disposed radially between the discharge passage  495  and the annular recess  488 . The bleed hole  500  may be in communication with an intermediate-pressure (higher than suction pressure and less than discharge pressure) fluid pocket  483  and the annular biasing chamber  492  and provides intermediate-pressure working fluid to the annular biasing chamber  492 . In this manner, the working fluid in the annular biasing chamber  492  biases the non-orbiting scroll  462  in an axial direction into engagement with the orbiting scroll  460 . 
     The variable volume ratio assembly  424  may include a valve housing  502 , a retaining ring  503 , a bypass valve member  504 , a spring member  506 , and a discharge valve member  510 . The valve housing  502  may act as a valve guide and valve stop for the bypass valve member  504  and the discharge valve member  510 . The valve housing  502  may be partially received in the opening  439  in the partition plate  437  and may extend into the discharge recess  493 . In some embodiments, the valve housing  502  can be press-fit into the opening  439 . A radially outwardly extending flange  511  of the valve housing  502  can be disposed within the suction chamber  443  and may contact the floating seal assembly  490 . 
     The valve housing  502  may include a first passage  512  extending therethrough and in fluid communication with the discharge recess  493  and the discharge chamber  442 . The valve housing  502  may include a second passage  514  in fluid communication with the discharge chamber  442  and disposed radially inward relative to the first passage  512 . The second passage  514  may include a first portion  515  and a second portion  517 . The second portion  517  may include a larger diameter than a diameter of the first portion  515  such that the second portion  517  defines an annular ledge  519 . The retaining ring  503  may be disposed within the discharge recess  493  and may engage the valve housing  502 . The retaining ring  503  may retain the bypass valve member  54  and the spring member  506  relative to the valve housing  502 , particularly during assembly of the compressor  410 . 
     The bypass valve member  504  may be a generally flat, annular member surrounding a portion of the valve housing  502  between the flange  511  and an axial end of the hub  486 . The bypass valve member  504  may be movable between a closed position ( FIG. 6 ) and an open position ( FIG. 7 ). In the closed position, the bypass valve member  504  is in contact with the end plate hub  486  and restricts or prevents fluid flow through the first and second bypass passages  496 ,  498  (i.e., restricting or preventing fluid communication between the bypass passages  496 ,  498  and the discharge chamber  442 ). In the open position, the bypass valve member  504  is spaced apart from the hub  486  and allows fluid flow through the first and second bypass passages  496 ,  498  (i.e., allowing fluid communication between the bypass passages  496 ,  498  and the discharge chamber  442  via the first passage  512  of the valve housing  502 ). The spring member  506  may be disposed between and in contact with the bypass valve member  504  and the flange  511  of the valve housing  502  such that the spring member  506  biases the bypass valve member  504  toward the closed position. 
     The discharge valve member  510  may be disposed within the discharge recess  493  and may include a stem portion  518  and a flange portion  520 . The stem portion  518  may be slidably received in the second portion  517  of the second passage  514  of the valve housing  502 . The discharge valve member  510  is movable between a closed position ( FIG. 6 ) and an open position ( FIG. 7 ). When the discharge valve member  510  is in the closed position, the flange portion  520  of the discharge valve member  510  is in contact with an annular ledge  522  defining a lower axial end of the discharge recess  493  to restrict or prevent fluid communication between the discharge recess  493  and the discharge passage  495  (thereby restricting or preventing fluid communication between the discharge passage  495  and the first passage  512  in the valve housing  502 ). When the discharge valve member  510  is in the open position, the flange portion  520  is spaced apart from the annular ledge  522  so that the discharge passage  495  is allowed to fluidly communicate with the discharge recess  493  and the first passage  512  of the valve housing  502 . The annular ledge  519  in the first passage  512  of the valve housing  502  may contact the stem portion  518  of the discharge valve member  510  in the fully open position (as shown in  FIG. 7 ). The first portion  515  of the second passage  514  of the valve housing  502  allows high-pressure fluid in the discharge chamber  442  to bias the discharge valve member  510  toward the closed position. 
     Operation of the variable volume ratio assembly  424  may be similar or identical to that of the variable volume ratio assembly  24 ,  224  described above. That is, the bypass valve member  504  may open to prevent an over-compression condition. When working fluid is being compressed by the scrolls  460 ,  462  to a pressure equal to or greater than the predetermined pressure by the time the pockets  483  containing the working fluid reaches the first and/or second bypass passages  496 ,  498 , the bypass valve member  504  will move into the open position to discharge the working fluid to the discharge chamber  442 , as described above. 
     It will be appreciated that the non-orbiting scroll  462  could include one or more other bypass passages in addition to the first and second bypass passages  496 ,  498 . In other configurations, the non-orbiting scroll  462  could include only one of the bypass passages  496 ,  498 . 
     With reference to  FIGS. 8 and 9 , another compressor  610  is provided that may have similar or identical structure and functions as the compressors  10 ,  210 ,  410  described above, apart from exceptions described below. Like the compressors  10 ,  210 , 410 , the compressor  610  may include a partition plate  637 , an orbiting scroll  660 , a non-orbiting scroll  662  and a variable volume ratio assembly  624 . The partition plate  637  may separate a discharge chamber  642  and a suction chamber  643 . The partition plate  637  includes a central opening  639  through which fluid is provided to the discharge chamber  642 . The partition plate  637  may also include first and second bypass openings  645 ,  647  that extend through the partition plate  637  and fluidly communicate with the discharge chamber  642 . 
     The non-orbiting scroll  662  includes an end plate  678  having a hub  686  and inner and outer annular grooves  688 ,  690 . The hub  686  may extend axially through the opening  639  in the partition plate  637 . The annular grooves  688 ,  690  may be substantially concentric with each other and the hub  686  and may surround the hub  686 . Inner and outer annular seals  691 ,  692  (similar or identical to the seals  91 ,  92 ,  291 ,  292 ) may be partially received in the annular grooves  688 ,  690 , respectively, and may sealingly contact the partition plate  637  and the end plate  678  to form an annular biasing chamber  697  therebetween, as described above. 
     The non-orbiting scroll  662  may also include a discharge passage  695 , first and second bypass passages  696 ,  698  and a bleed hole (not shown; similar to the bleed hole  100 ,  300  described above) that extend through the end plate  678 . The discharge passage  695  may extend axially through the hub  686  and may be in fluid communication with a central fluid pocket  683  defined by the scrolls  660 ,  662 . The bleed hole may also be disposed radially between the inner and outer annular grooves  688 ,  690  and may be in communication with an intermediate-pressure (higher than suction pressure and less than discharge pressure) fluid pocket  683  and the annular biasing chamber  697  to provide intermediate-pressure working fluid to the annular biasing chamber  697 . The bleed hole may be disposed radially outward relative to the first and second bypass passages  696 ,  698 . 
     The first and second bypass passages  696 ,  698  are variable volume ratio passages disposed radially outward relative to the discharge passage  695  and the hub  686  and are in fluid communication with respective ones of the fluid pockets  683 . The first and second bypass passages  696 ,  698  may be disposed radially between the inner annular groove  688  and the outer annular groove  690 , but are fluidly isolated from the annular biasing chamber  697 . The first and second bypass passages  696 ,  698  may be axially aligned with the first and second bypass openings  645 ,  647 , respectively, of the partition plate  637 . A first annular seal  649  is partially received in a recess  651  of the first bypass passage  696  and sealingly engages the end plate  678  and the partition plate  637  to fluidly isolate the first bypass passage  696  and the first bypass opening  645  from the annular biasing chamber  697 . A second annular seal  653  is partially received in a recess  655  of the second bypass passage  698  and sealingly engages the end plate  678  and the partition plate  637  to fluidly isolate the second bypass passage  698  and the second bypass opening  647  from the annular biasing chamber  697 . 
     The variable volume ratio assembly  624  may include first and second bypass valve retainers  702 ,  703 , first and second bypass valve members  704 ,  705 , a discharge valve retainer  708  and a discharge valve member  710 . The bypass valve retainers  702 ,  703  and the bypass valve members  704 ,  705  can be mounted to the partition plate  637  within the discharge chamber  642  such that the bypass valve members  704 ,  705  are clamped between the respective bypass valve retainers  702 ,  703  and the partition plate  637 . 
     The bypass valve members  704 ,  705  may be reed valves that are flexible between open positions ( FIG. 8 ) in which the bypass valve members  704 ,  705  allow fluid communication between the first and second bypass passages  696 ,  698  and the discharge chamber  642  and closed positions ( FIG. 9 ) in which the bypass valve members  704 ,  705  restrict or prevent fluid communication between the first and second bypass passages  696 ,  698  and the discharge chamber  642 . The bypass valve retainers  702 ,  703  may be rigid members that define a range of flexing movement of the bypass valve members  704 ,  705 . 
     The discharge valve retainer  708  and the discharge valve member  710  can have similar or identical structure and function as the discharge valve retainer  108 ,  308  and the discharge valve member  110 ,  310 . The discharge valve retainer  708  can be mounted directly to the partition plate  637 . As described above with respect to the discharge valve retainer  108 , the discharge valve retainer  708  may include a central hub  726  defining a cavity  730 . The hub  686  of the non-orbiting scroll  662  may extend into the cavity  730  and an axial end of the hub  686  may define a valve seat  731  for the discharge valve member  710 . That is, the discharge valve member  710  contacts the valve seat  731  when the discharge valve member  710  is in the closed position to restrict or prevent fluid communication between the discharge passage  695  and the discharge chamber  642 . 
     Operation of the variable volume ratio assembly  624  may be similar or identical to that of the variable volume ratio assembly  24 ,  224 ,  424  described above. That is, the bypass valve members  704 ,  705  may open to prevent an over-compression condition. When working fluid is being compressed by the scrolls  660 ,  662  to a pressure equal to or greater than the predetermined pressure by the time the pockets  683  containing the working fluid reaches the first and/or second bypass passages  696 ,  698 , the bypass valve members  704 ,  705  will move into the open position to discharge the working fluid to the discharge chamber  642 , as described above. 
     It will be appreciated that the non-orbiting scroll  662  could include one or more other bypass passages in addition to the first and second bypass passages  696 ,  698 . In other configurations, the non-orbiting scroll  662  could include only one of the bypass passages  696 ,  698 . 
     With reference to  FIGS. 10-12 , various alternative configurations of the bypass valve member  104 ,  304 ,  504  and the spring member  106 ,  306 ,  506  will be described. As described above, the bypass valve member  104 ,  304 ,  504  may be flat, annular members. The spring member  106 ,  306 ,  506  can be fixedly attached to the bypass valve member  104 ,  304 ,  504  or integrally formed therewith. For example, the spring member  106 ,  306 ,  506  can be welded, cinched or otherwise fixed to the bypass valve member  104 ,  304 ,  504 . As shown in  FIG. 10 , the spring member  106 ,  306 ,  506  can be a single, continuous wave ring that is resiliently compressible. As shown in  FIG. 11 , the spring member  106 ,  306 ,  506  can include a plurality of resiliently flexible arcuate fingers. As shown in  FIG. 12 , the spring member  106 ,  306 ,  506  can include a plurality of resiliently compressible helical coil springs. It will be appreciated that the spring member  106 ,  306 ,  506  could be otherwise shaped and/or configured. 
     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.