Patent Publication Number: US-2023147568-A1

Title: Co-Rotating Compressor

Description:
FIELD 
     The present disclosure relates to a compressor in a refrigeration system and, more particularly, to a co-rotating compressor. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     Cooling systems, refrigeration systems, heat-pump systems, and other climate-control systems include a fluid circuit having a condenser, an evaporator, an expansion device disposed between the condenser and evaporator, and a compressor circulating a working fluid between the condenser and the evaporator. Efficient and reliable operation of the compressor is desirable to ensure that the cooling, refrigeration, or heat pump system in which the compressor is incorporated is capable of effectively and efficiently providing a cooling and/or heating effect on demand. 
     The compressor takes working fluid from a suction end, compresses the fluid, and discharges the working fluid through a discharge outlet. The compression process generates heat within the compressor. Additionally, the motor generates its own heat. In some cases, the heat may be dissipated naturally. However, in some cases, additional cooling may be necessary to dissipate heat and reduce motor temperatures. Reduction in motor temperatures results in lower potential for motor overheating and failure. 
     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. 
     An example compressor according to the present disclosure includes a compression mechanism, a driveshaft, and a motor. The compression mechanism may be configured to compress a fluid to a discharge pressure. The motor may be configured to rotate the driveshaft. The driveshaft may be engaged with the compression mechanism and may be fixed to rotate with at least a portion of the compression mechanism. The driveshaft may include a longitudinal aperture configured to receive the fluid at a suction pressure, and includes a flange that receives at least a portion of the compression mechanism. The flange and the compression mechanism may define a fluid passage therebetween. The fluid at suction pressure may be received within the fluid passage from the longitudinal aperture in the driveshaft. 
     The example compressor may further include a shell defining an internal space. The compression mechanism, the driveshaft, and the motor may be disposed within the shell. The fluid at suction pressure or the fluid at discharge pressure may circulate through the internal space and the motor is configured to transfer heat away from the motor. 
     The shell may include a body, an endcap, and a partition. The body may define the internal space. The endcap and the partition may define a discharge-pressure chamber. The internal space may be a suction-pressure chamber. 
     The shell may include a body, an endcap, and a partition. The body may define the internal space. The endcap and the partition may define a suction-pressure chamber. The internal space may be a discharge-pressure chamber. 
     The example compressor may further include a shaft engaged with the compression mechanism and fixed in a stationary position. The shaft may include a longitudinal discharge aperture. The longitudinal discharge aperture may be in fluid communication with a discharge port of the compression mechanism. 
     The example compressor may further include a bearing housing fixed to rotate with at least a portion of the compression mechanism. The shaft may be supported within the bearing housing by a first bearing. The shaft may be supported within the compression mechanism by a second bearing. 
     The example compressor may further include a first seal engaged with the shaft and the bearing housing. The first seal may be configured to prevent flow of fluid from the compression mechanism or an interface between the discharge port and the longitudinal discharge aperture. 
     The motor may be fixed radially outside of the bearing housing. 
     The example compressor may further include a shell configured to house the compression mechanism, the driveshaft, and the motor. The shell may include a body, an endcap, and a partition. The shaft may be fixed to or integral with the endcap. 
     The example compressor may further include a shell configured to house the compression mechanism, the driveshaft, and the motor. The shell may include a body, an endcap, and a partition. The shaft may be fixed to or integral with the partition. 
     The compression mechanism may include an orbiting scroll and a non-orbiting scroll. The orbiting scroll may be fixed for rotation with the flange and may include an axial passage in fluid communication with the fluid passage between the compression mechanism and the flange. 
     The driveshaft may be supported by a bearing on a proximal end and engaged with the compression mechanism on a distal end. 
     The example compressor may include a seal engaged with the driveshaft and the bearing. The seal may be configured to prevent flow of fluid from a suction-pressure inlet or an interface between the suction pressure inlet and the driveshaft. 
     The example compressor may include an impeller disposed between the compression mechanism and the flange. The impeller may define the fluid passage. 
     The impeller may be formed with an end plate of the compression mechanism as a single, monolithic part. 
     An example compressor according to the present disclosure includes a shell, a compression mechanism, a driveshaft, and a motor. The shell may have a body, an end cap, and a partition. The compression mechanism may be housed within the shell and may be configured to compress a fluid to a discharge pressure. The driveshaft may be housed within the shell, engaged with the compression mechanism, and fixed to rotate with at least a portion of the compression mechanism. The motor may be housed within the shell and configured to rotate the driveshaft. The driveshaft may include a longitudinal aperture configured to receive the fluid at a suction pressure. The body, the end cap, and the partition defining one of a discharge-pressure chamber and a suction-pressure chamber. The compression mechanism and the motor may be housed in the one of the discharge-pressure chamber and the suction-pressure chamber. 
     The body, the end cap, and the partition may define the discharge-pressure chamber. 
     The body, the end cap, and the partition may define the suction-pressure chamber. 
     An example compressor according to the present disclosure includes a shell, a compression mechanism, a driveshaft, and a motor. The shell may include a body, an end cap, and a partition. The compression mechanism may be housed within the shell and configured to compress a fluid to a discharge pressure. The driveshaft may be housed within the shell, engaged with the compression mechanism, and fixed to rotate with at least a portion of the compression mechanism. The motor may be housed within the shell and configured to rotate the driveshaft. The fluid passage may extend from a fluid inlet to a fluid outlet, and the fluid passage may extend through a longitudinal aperture in the driveshaft and the compression mechanism. The fluid passage may extend into the shell and through the motor to transfer heat away from the motor. 
     The body, the end cap, and the partition may define one of a discharge-pressure chamber and a suction-pressure chamber. The motor may be housed in the one of the discharge-pressure chamber and the suction-pressure chamber. 
     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 an example compressor according to the present disclosure. 
         FIG.  2    is another cross-sectional view of the compressor of  FIG.  1   . 
         FIG.  3    is an exploded view of the compressor of  FIG.  1   . 
         FIG.  4    is a cross-sectional view of another example compressor according to the present disclosure. 
         FIG.  5    is an exploded view of the compressor of  FIG.  4   . 
         FIG.  6    is a cross-sectional view of another example compressor according to the present disclosure. 
         FIG.  7    is an exploded view of the compressor of  FIG.  6   . 
         FIG.  8    is another exploded view of the compressor of  FIG.  6   . 
         FIG.  9    is a cross-sectional view of another example compressor according to the present disclosure. 
         FIG.  10    is an exploded view of the compressor of  FIG.  9   . 
         FIG.  11    is a cross-sectional view of another example compressor according to the present disclosure. 
         FIG.  12    is an exploded view of the compressor of  FIG.  11   . 
         FIG.  13    is a cross-sectional view of another example compressor according to the present disclosure. 
         FIG.  14    is an exploded view of the compressor of  FIG.  13   . 
     
    
    
     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. 
     The present disclosure relates to refrigerant flow through a sumpless co-rotating scroll compressor. Co-rotating compressor technology allows for a reduction in size due to the absence of counterweights and reduction of flank forces. 
     With reference to  FIG.  1   , a compressor  10  is provided that may include a hermetic shell assembly  12 , a bearing housing assembly  14 , a motor assembly  16 , and a compression mechanism  18 . 
     The shell assembly  12  may generally form a compressor housing and may include a cylindrical shell  22 , a first end cap  24  at one end of the shell  22 , a partition  25  and a second end cap  26  at another end of the shell  22 . The shell  22  and the first end cap  24  may cooperate to define a suction-pressure chamber  30 . A suction gas inlet fitting  32  may be attached to the shell assembly  12  at an opening in the first end cap  24 . Suction-pressure working fluid (i.e., low-pressure working fluid) may be drawn into the compression mechanism  18  via the suction gas inlet fitting  32  for compression therein. 
     As shown in  FIGS.  1  and  2   , the partition  25  and the second end cap  26  may cooperate to define a discharge-pressure chamber  33 . The partition  25  may separate the discharge-pressure chamber  33  from the suction-pressure chamber  30 . A discharge gas outlet fitting  34  may be attached to the shell assembly  12  at another opening in the second end cap  26  and may communicate with the discharge-pressure chamber  33 . Discharge-pressure working fluid (i.e., working fluid at a higher pressure than suction pressure) may be discharged by the compression mechanism  18  and may flow into the discharge-pressure chamber  33 . The discharge-pressure working fluid in the discharge-pressure chamber  33  may exit the compressor  10  through the discharge-gas-outlet fitting  34 . In some configurations, a discharge valve (e.g., a check valve) may be disposed within or adjacent the discharge-gas-outlet fitting  34  and may allow fluid to exit the discharge-pressure chamber  33  through the discharge-gas-outlet fitting  34  and prevent fluid from entering the discharge-pressure chamber  33  through the discharge-gas-outlet fitting  34 . 
     The bearing housing assembly  14  may be disposed within the suction-pressure chamber  30  and may include a main bearing housing  38  and a bearing  40 . The main bearing housing  38  may house the bearing  40  therein. The bearing  40  may be a rolling element bearing or any other suitable type of bearing. The main bearing housing  38  may include a plurality of cylindrically-shaped fasteners, such as pins or bolts,  41  ( FIG.  3   ) extending in an axial direction from an axial end surface  42  of the main bearing housing  38 . The fasteners  41  may be spaced apart from each other and may be disposed circumferentially around the axial end surface  42  of the main bearing housing  38 . Each fastener  41  may have a proximate end  43  and a distal end  44 . The proximate end  43  may extend from the axial end surface  42  of the main bearing housing  38 . The distal end  44  may be coupled to a hub  50  engaged with the driveshaft  46  such that the bearing housing  38  is coupled to the driveshaft  46 . In some configurations, the fasteners  41  may be separate components that are attached to the axial end surface  42  of the main bearing housing  38  through threads or a press-fit instead of being integrally formed with the axial end surface  42  of the main bearing housing  38 . 
     The motor assembly  16  may be disposed within the suction-pressure chamber  30  and may include a motor stator  52  and a rotor  54 . The motor stator  52  may be attached to the shell  22  (e.g., via press fit, staking, and/or welding). The rotor  54  may be attached to the driveshaft  46  (e.g., via press fit, staking, and/or welding). The driveshaft  46  may be driven by the rotor  54  and may be supported by bearing  59  for rotation relative to the shell assembly  12 . The bearing  59  may be fixed to the first end cap  24  of the shell assembly  12 . In some configurations, the motor assembly  16  is a variable-speed motor. In other configurations, the motor assembly  16  could be a multi-speed motor or a fixed-speed motor. 
     The driveshaft  46  may include a driveshaft section  56  and the hub  50 . The driveshaft section  56  may include a suction passage  62 . The suction passage  62  provides fluid communication between the suction gas inlet fitting  32  and the compression mechanism  18 . An inlet  64  of the suction passage  62  may be disposed at or near a first end  65  of the driveshaft section  56  adjacent the suction gas inlet fitting  32 . An outlet  66  of the suction passage  62  may be disposed at or near a second end  67  of the driveshaft section  56  adjacent to the compression mechanism  18 . The second end  67  of the driveshaft section  56  may include a flange  68  for engaging the driveshaft section  56  with the hub  50 . The suction passage  62  may be coated in a thermal insulation coating to prevent preheat of the working fluid. For example, the thermal insulation coating may include, but is not limited to, ceramics, silicone or thermal insulating sprays. 
     A first axial portion  58  of the hub  50  may engage with the second end  67  of the driveshaft section  56 . More particularly, the flange  68  on the second end  67  of the driveshaft section  56  may be fixed to the first axial portion  58  of the hub  50 . The hub  50  may further include a radial portion  70 , a second axial portion  72 , and a flange  74 . The radial portion  70  extends in a radial direction from the first axial portion  58  of the hub  50  (in a direction perpendicular to a rotational axis A 1  of driveshaft  46 ) and the second axial portion  72  extends in an axial direction from a periphery of the radial portion  70  (in a direction parallel to a rotational axis A 1  of driveshaft  46 ). The flange  74  extends in a radial direction from an end of the second axial portion  72  and includes a plurality of fastener housings  75 . As shown in  FIG.  3   , the fastener housings  75  are spaced apart from each other and are circumferentially disposed around the flange  74 . Each fastener  41  extending from the main bearing housing  38  is received in a respective fastener housing  75 , thereby coupling the main bearing housing  38  and the hub  50  to each other. In this manner, rotation of the driveshaft  46  causes corresponding rotation of the main bearing housing  38  about the rotational axis A 1  of the driveshaft  46 . 
     The compression mechanism  18  may be disposed within the suction-pressure chamber  30 . The compression mechanism  18  may include a first compression member and a second compression member that cooperate to define fluid pockets (i.e., compression pockets) therebetween. For example, the compression mechanism  18  may be a co-rotating scroll compression mechanism in which the first compression member is a first scroll member (i.e., a driver scroll member)  76  and the second compression member is a second scroll member (i.e., a driven scroll member)  78 . 
     The first scroll member  76  may include a first end plate  80  and a first spiral wrap  82  extending from the first end plate  80 . The first end plate  80  is disposed within and fixed to the flange  50  of the driveshaft  46  such that the flange  50  surrounds the first spiral wrap  82 . In some configurations, the first scroll member  76  and the driveshaft  46  may be a single component as opposed two separate components fixed to each other. The first end plate  80  may include an axially extending passage  83 . A radially extending passage  84  is formed between the first end plate  80  and the flange  50  and extends from a central area of the first end plate  80  to the axially extending passage  83 . The axially extending passage  83  extends from an end of the radially extending passage  84  to a suction inlet  85  of the first scroll member  76 . In this way, suction gas flowing through the suction passage  62  may flow through the passages  83 ,  84  and into an outermost pocket of the fluid pockets via the suction inlet  85 . A portion of the suction gas flowing through the passages  83 ,  84  may exit into the suction pressure-chamber  30 . 
     The second scroll member  78  defines a second rotational axis A 2  that is parallel to the rotational axis A 1  and offset from the rotational axis A 1 . The second scroll member  78  may include a second end plate  86 , a cylindrical hub  88  extending from one side of the second end plate  86 , and a second spiral wrap  90  extending from the opposite side of the second end plate  86 . A stationary crank  92  with discharge passage  93  is coupled to the partition  25  and includes a first end  94  extending at least partially into the discharge-pressure chamber  33  and a second end  96  extending through the bearing  40  and into the hub  88  (the bearing  40  is disposed within the suction-pressure chamber  30 ). The passage  93  extends axially through the stationary crank  92  (i.e., through the first and second ends  94 ,  96 ) and provides fluid communication between the compression mechanism  18  and the discharge-pressure chamber  33 . The discharge passage  93  may be coated with a thermal insulation coating to prevent heat transfer from the compressed working fluid to the compressor parts. For example, the thermal insulation coating may include, but is not limited to, ceramics, silicone or thermal insulating sprays. The hub  88  of the second scroll member  78  is rotatably supported by a bearing  98  (e.g., a needle bearing) that is positioned between the hub  88  and the stationary crank  92 . Oldham coupling  95  may provide synchronized rotational motion of the driven scroll  78  from the housing  38 . 
     A sealing assembly  102  is disposed within the main bearing housing  38  and includes a housing  104  and a sealing member  106 . The housing  104  is press-fitted within the main bearing housing  38  such that an outer diametrical surface  107  of the housing  104  is sealingly engaged with an inner diametrical surface  108  of the main bearing housing  38 . The sealing member  106  is disposed within the housing  104  and is sealingly engaged with an outer diametrical surface  109  of the stationary crank  92 . In this way, fluid discharged from the fluid pockets of the compression mechanism  18  is prevented from flowing to the bearing  40  and to the suction chamber  30 . 
     The first and second spiral wraps  82 ,  90  are intermeshed with each other and cooperate to form a plurality of fluid pockets (i.e., compression pockets) therebetween. Synchronized rotation of the first scroll member  76  about the rotational axis A 1  and rotation of the second scroll member  78  about the second rotational axis A 2  causes the fluid pockets to decrease in size as they move from a radially outer position to a radially inner position, thereby compressing the working fluid therein from the suction pressure to the discharge pressure. 
     The second end plate  86  may be disposed axially between the first end plate  80  and the main bearing housing  38 . Annular seals  110  may be disposed within a groove  111  formed in an axial surface  113  of the main bearing housing  38  and may sealingly and slidably engage the end of hub  88  to form an annular biasing chamber  112 . The annular seals  110  keeps the biasing chamber  112  sealed off from the suction-pressure chamber  30  and the discharge gas while still allowing relative movement between the main bearing housing  38  and the second scroll member  78 . The second end plate  86  may include a biasing passage  115  that provides fluid communication between an intermediate-pressure compression pocket and the biasing chamber  112 . 
     The second end plate  86  may include a discharge passage  114 . The discharge passage  114  extends through the second end plate  86  and provides fluid communication between a radially innermost one of the fluid pockets and the discharge-gas-outlet fitting  34  (via the passage  93  in the stationary crank  92 ). A discharge valve (e.g., a reed valve or other check valve) may be disposed within or adjacent the discharge passage  114  or at the end  94  of the stationary crank  92 . The discharge valve allows working fluid to be discharged from the compression mechanism  18  through the discharge passage  114  and into the stationary crank  92  and prevents working fluid in the stationary crank  92  from flowing back into to the compression mechanism  18 . The discharge gas flowing out of the discharge passage  114  may flow through the passage  93  of the stationary crank  92 , into the discharge-pressure chamber  33  and out of the compressor  10  through the discharge-gas-outlet fitting  34 . 
     Following the arrows in  FIGS.  1  and  2   , during use, a working fluid enters the inlet  65  of the compressor  10  through the suction inlet fitting  32  on the first end  67  of the compressor  10  (Arrow A). The working fluid may include both a refrigerant and an oil (for example, an oil mist). Since the compressor  10  is a sumpless compressor, the oil for heat transfer and lubrication of moving parts travels with the working fluid through the compressor  10 . For example, the refrigerant may include, but is not limited to, one or more of R410a, R290, R744, R32 R454b, R134a, 404A, 407A/C/F, 507, and R717. For example, the oil may include, but is not limited to, one or more of Mineral Oil, Alkyl Benzene, Polyol Ester, and Polyalkylene glycol, as a few examples. 
     The working fluid, at suction pressure, is pulled into the suction passage  62  within the driveshaft  56 . The working fluid moves through the driveshaft  56  towards the compression mechanism  18  (Arrow A). The working fluid travels through the output  66  of the suction passage  62  and into the radially extending passage  84  defined by the space between the hub  50  and the first end plate  80  (Arrow B). A portion of the suction gas flowing through the passages  83 ,  84  may exit into the suction pressure-chamber  30 . 
     The portion of the working fluid pulled into the suction pressure chamber  30  is circulated through the motor assembly  16  to cool and lubricate the motor assembly  16  (Arrows C). For example, the working fluid is circulated through the stator  52  and rotor  54  to absorb heat generated by operation of the rotor  54  and cool the motor assembly  16 . 
     The main portion of the working fluid is received in the axially extending passage  83  (Arrow D) from the radially extending passage  84  (Arrow B). The axially extending passage  83  provides an entrance into the suction inlet  85  in the compression mechanism  18 . The working fluid is compressed within the pockets defined by the first spiral wrap  82  of the first, driving scroll  76  and the second spiral wrap  90  of the second, driven scroll  78  (Arrow E). 
     The compressed working fluid is discharged through the discharge passage  114  in the second end plate  86  of the second, driven scroll  78  (Arrow F). The compressed working fluid is at a high-pressure (i.e., compression pressure) and flows through the discharge passage  93  in the stationary crank  92 . The sealing assembly  102  isolates the compressed, high-pressure working fluid from the low-pressure suction pressure chamber  30 . The compressed working fluid enters the discharge pressure chamber  33  (Arrow G) and exits the compressor  10  through the discharge outlet fitting  34  (Arrow H). 
     Now referring to  FIG.  4   , an example compressor  200  is illustrated. Compressor  200  may be the same as compressor  10 , except that compressor  200  may include an impeller  204  disposed between the hub  50  and the first end plate  80  of the first scroll  76 , which defines the suction plenum. Like parts between compressors  10  and  200  are shown using the same reference numbers. 
     As illustrated in  FIGS.  4  and  5   , the impeller  204  defines a passage  208  extending from the outlet  66  of the suction passage  62  to the axially extending passage  83  to streamline the gas flow from the suction passage  62  to the scroll suction port  85 . The streamlined flow may reduce pressure drops between the suction passage  62  and the compression mechanism  18 . Additionally, the streamlined flow may, in certain conditions, provide a supercharging effect. 
     Additionally, the impeller  204  provides pre-compression of the working fluid. The working fluid is dynamically compressed prior to the compression mechanism  18  utilizing a centrifugal effect. 
     The surface forming impeller cavity shape  204  may be formed of a thermally insulated material. For example, the thermally insulated material may include, but is not limited to, ceramics, silicone thermal insulating sprays, plastics, ceramics, or graphite. The thermally insulating impeller  204  may reduce the heat transfer into the refrigerant flowing through the passage  208  toward the suction inlet  85 . Reduction in the heat transfer may improve the volumetric efficiency of the refrigerant. 
     The impeller  204  may be formed integrally with the first end plate  80  of the first scroll member  76  to create a single, monolithic piece. Accordingly, the position of the impeller  204  relative to the first scroll member  76  may be fixed. Further, forming the impeller  204  with the first end plate  80  creates easier and more reliable assembly of the compressor  200 . 
     Alternatively, the impeller  204  may fit within a recessed portion in the first end plate  80  of the first scroll member  76 . The recessed portion may locate and fix the position of the impeller  204  relative to the hub  50  and the first scroll member  76 . 
     Alternatively, the impeller  204  may be formed integrally with the hub  50  or with the driveshaft  56 . 
     Following the arrows in  FIG.  4   , during use, a working fluid enters the inlet, or suction passage,  62  of the compressor  200  (Arrow A). The working fluid may include both a refrigerant and an oil (for example, an oil mist). Since the compressor  10  is a sumpless compressor, the oil for heat transfer and lubrication of moving parts travels with the working fluid through the compressor  10 . For example, the refrigerant may include, but is not limited to, one or more of R410a, R290, R744, R32 R454b, R134a, 404A, 407A/C/F, 507, and R717. For example, the oil may include, but is not limited to, one or more of Mineral Oil, Alkyl Benzene, Polyol Ester, and Polyalkylene glycol, as a few examples. 
     The working fluid, at suction pressure, is pulled into the suction passage  62  within the driveshaft  56 . The working fluid moves through the driveshaft  56  towards the compression mechanism  18  (Arrow A). The working fluid travels through the outlet  66  of the suction passage  62  and into the passage  208  defined by the impeller  204  (Arrow B). A portion of the suction gas flowing through the passage  208  may exit into the suction pressure-chamber  30 . 
     The portion of the working fluid pulled into the suction pressure chamber  30  is circulated through the motor assembly  16  to cool the motor assembly  16  (Arrows C). For example, the working fluid is circulated through the stator  52  and rotor  54  to absorb heat generated by operation of the rotor  54  and cool the motor assembly  16 . 
     The main portion of the working fluid is received in the axially extending passage  83  from the passage  208  (Arrow D). The axially extending passage  83  provides an entrance into the suction inlet  85  in the compression mechanism  18 . The working fluid is compressed within the pockets defined by the first spiral wrap  82  of the first, driving scroll  76  and the second spiral wrap  90  of the second, driven scroll  78  (Arrow E). 
     The compressed working fluid is discharged through the discharge passage  114  in the second end plate  86  of the second, driven scroll  78  (Arrow F). The compressed working fluid is at a high-pressure (i.e., compression pressure) and flows through the discharge passage  93  in the stationary crank  92 . The sealing assembly  102  isolates the compressed, high-pressure working fluid from the low-pressure suction pressure chamber  30 . The compressed working fluid enters the discharge pressure chamber  33  (Arrow G) and exits the compressor  10  through the discharge outlet fitting  34  (Arrow H). 
     Now referring to  FIGS.  6 - 8   , an example compressor  300  is provided that may include a shell assembly  312 , a first bearing housing  314 , a second bearing housing  316 , a compression mechanism  318 , and a motor assembly  320 . The shell assembly  312  may include a shell body  322 , a first end cap  323 , and a second end cap  324 . The shell body  322  may be generally cylindrical. The first and second end caps  323 ,  324  may be fixedly attached to opposing axial ends of the shell body  322 . 
     The first end cap  323 , the shell body  322 , and the second end cap  324  may cooperate to define a suction chamber  328 . The first and second bearing housings  314 ,  316 , the compression mechanism  318 , and the motor assembly  320  may be disposed within the suction chamber  328 . The suction chamber  328  may receive suction-pressure working fluid from a suction inlet fitting  330  attached to the second end cap  324  or shell body  322 . That is, suction-pressure working fluid (i.e., low-pressure working fluid) may enter the suction chamber  328  through the suction inlet fitting  330  and may be drawn into the compression mechanism  318  for compression therein. The compression mechanism  318  discharges compressed working fluid (i.e., discharge-pressure working fluid at a higher pressure than suction pressure) from the compressor  310  through a discharge outlet fitting  332  attached to the second end cap  324 . For example, the compression mechanism  318  is in direct communication with the discharge outlet fitting, or compressor output,  332 , without use of a discharge chamber. In some configurations, a discharge valve (for example, a check valve) may be disposed within the discharge outlet fitting that allows fluid to exit the discharge outlet fitting  332  and prevents fluid from entering the compressor  310  through the discharge outlet fitting  332 . 
     The compressor  300  shown in the figures is a low-side compressor (i.e., the motor assembly  320  and at least a majority of the compression mechanism  318  are disposed in the suction chamber  328 ). It will be appreciated, however, that the principles of the present disclosure are applicable to high-side compressors (i.e., compressors having the compression mechanism  318  disposed in a discharge chamber). 
     The first bearing housing  314  may include a first bearing support member  338  and a second bearing support member  340 . The first bearing support member  338  may be a generally cylindrical shaft or body having a discharge passage  342  extending axially therethrough. The first bearing support member  338  may be fixed relative to the shell assembly  312 , forming a stationary shaft. For example, the first bearing support member  338  may be, monolithically formed with, or fixedly attached to, the discharge outlet fitting  332  and may extend through an opening  344  in the second end cap  324 . In other configurations, the first bearing support member  338  may be attached to or integrally formed with the second end cap  324 . The discharge passage  342  is in fluid communication with the discharge outlet fitting  332  and the compression mechanism  318  such that compressed working fluid discharged from the compression mechanism  318  flows through the discharge passage  342  into the discharge outlet fitting  332  and exits the compressor  300 . 
     The first bearing support member  338  includes a first cylindrical surface  346  and a second cylindrical surface  348 . The first cylindrical surface  346  may support a first bearing  350  and may define a first rotational axis A 1 . The second cylindrical surface  348  is eccentric relative to the first cylindrical surface  346  and defines a second rotational axis A 2  that is parallel to and laterally offset from the first rotational axis A 1 . The second cylindrical surface  348  supports a second bearing  352 . 
     The first and second bearings  350 ,  352  may be rolling element bearings that each may include an outer ring  354 , an inner ring  356 , and a plurality of rolling elements (e.g., spheres or cylinders)  358  disposed between the outer and inner rings  354 ,  356 . The inner ring  356  of the first bearing  350  may be fixedly attached to the first cylindrical surface  346  of the first bearing support member  338 . The outer ring  354  of the first bearing  350  may be attached to the second bearing support member  340 . The inner ring  356  of the second bearing  352  may be fixedly attached to the second cylindrical surface  348  of the first bearing support member  338 . Alternatively, a clearance between the inner ring  356  of the second bearing  352  and the second cylindrical surface  348  may achieve radial compliancy. The outer ring  354  of the second bearing  352  may be attached to the compression mechanism  318  (as will be described in more detail below). Alternatively, the second bearing  352  may be attached to the first bearing support member  338  or the compression mechanism  318  to provide radial compliance. Radial compliance would allow the second bearing  352  to separate sideways from the first bearing support member  338  or the compression mechanism  318 , which may allow debris to pass through and improve durability and reliability. 
     The second bearing support member  340  may be an annular member having a first cavity  341  and a second cavity  343 . The first cavity  341  may receive the first bearing  350 . The second cavity  343  may receive a portion of the compression mechanism  318 . The second bearing support member  340  may include a plurality of slots  361  ( FIG.  8   ). For example, the slots  361  may be formed in an axially facing surface  363  (i.e., a surface that faces a direction parallel to the direction in which axes A 1 , A 2  extend) of the second bearing support member  340 . A plurality of radial drillings  367  may be disposed between the outer and inner surfaces of the bearing housing  316  to feed the excess oil accumulated at the cavity  328  into the suction stream A. 
     An annular seal  365  may be disposed within the second bearing support member  340  (e.g., axially between the first and second cavities  341 ,  343 ). The seal  365  may sealingly engage the second bearing support member  340  and the first bearing support member  338 . Another annular seal  366  sealingly engages the second bearing support member  340  and a second scroll member  372 . The seals  365 ,  366  prevent compressed working fluid (i.e., working fluid discharged from the compression mechanism  318 ) from flowing into the suction chamber  328  and intermediate pressure cavity  343 , respectively. 
     The second bearing housing  316  may include an annular central hub  360 . The hub  360  receives a third bearing  362 . The hub  360  may also include a central aperture  364 . The hub  360  may also include at least one radial drilling  363  to bring oil accumulated at the bottom of the cavity  328  into the suction passage  384 . 
     The compression mechanism  318  may include a driveshaft  368 , a first scroll member  370 , the second scroll member  372 , and an Oldham coupling (or Oldham ring)  376 . The first and second scroll members  370 ,  372  cooperate to define fluid pockets (i.e., compression pockets) therebetween. The compression mechanism  318  is a co-rotating scroll compression mechanism in which the first scroll member  370  is a driving scroll member and the second scroll member  372  is a driven scroll member. 
     The driveshaft  368  may include a shaft portion  378  and a hub  380 . The shaft portion  378  is rotatably supported by the third bearing  362  and extends through the motor assembly  320 . The hub  380  extends radially outward from an axial end of the shaft portion  378 . Fasteners  382  may extend through apertures in the hub  380 , the first scroll member  370 , and the second bearing support member  340  to rotationally fix the first scroll member  370  and the second bearing support member  340  relative to the driveshaft  368  (i.e., so that the first scroll member  370  and second bearing support member  340  rotate with the driveshaft  368  about the first rotational axis A 1 ). The driveshaft  368  may include one or more apertures  384  through which suction-pressure working fluid from the suction inlet fitting  330  as well as from the suction chamber  328  can flow into a suction inlet opening  386  ( FIG.  7   ) in the first scroll member  370 . The suction inlet opening  386  may be an axially extending passage that terminates in a suction inlet in the first scroll member  370 . The one or more apertures  384  define a suction passage in the driveshaft  368 . 
     The first scroll member  370  may include a first end plate  388  and a first spiral wrap  390  extending from the first end plate  388 . The suction inlet opening  386  may be disposed in the first end plate  388 . The suction inlet opening  386  may be in fluid communication with the aperture  384  through a passage  391  defined by a space between the first end plate  388  and the hub  380 . The passage  391  may be a radially extending passage that extends perpendicular to the aperture  384 . 
     The second scroll member  372  may include a second end plate  392 , a second spiral wrap  394  extending from one side of the second end plate  392 , and a hub  396  extending from the opposite side of the second end plate  392 . The second end plate  392  may include a discharge passage  398  that is in fluid communication with the discharge passage  342  in the first bearing support member  338 . 
     The second scroll member  372  may be disposed within the second cavity  343  of the second bearing support member  340 . The eccentric second cylindrical surface  348  of the first bearing support member  338  may be received within the hub  396  of the second scroll member  372 . The hub  396  of the second scroll member  372  may be rotatably supported by the second bearing  352  and the eccentric second cylindrical surface  348  of the first bearing support member  338 . In this manner, the second scroll member  372  is rotatable about the second rotational axis A 2 . As shown in  FIG.  7   , the second end plate  392  of the second scroll member  372  includes a plurality of slots  400 . 
     The Oldham coupling  376  may be keyed to the second bearing support member  340  and the second scroll member  372 . The Oldham coupling  376  may include an annular body  402  and keys  404 . The keys  404  may be rectangular protrusions (i.e., rectangular prisms). The keys  404  on the same side of the annular body  402  may be disposed approximately 180 degrees apart from each other. The keys  404  extend axially from both opposing sides of the annular body  402 . The keys  404  are slidably received in respective slots  361 ,  400  of the second bearing support member  340  and second scroll member  372 . 
     The Oldham coupling  376  transmits rotational energy of the driveshaft  368 , through the second bearing support member  340  to the second scroll member  372  such that the driveshaft  368 , first scroll member  370  and second bearing support member  340  rotate about the first rotational axis A 1  causing synchronized rotation of the second scroll member  372  about the second rotational axis A 2 . The first and second spiral wraps  390 ,  394  are intermeshed with each other and cooperate to form a plurality of fluid pockets (i.e., compression pockets) therebetween. Rotation of the first scroll member  370  about the first rotational axis A 1  and rotation of the second scroll member  372  about the second rotational axis A 2  causes the fluid pockets to decrease in size as they move from a radially outer position to a radially inner position, thereby compressing the working fluid therein from the suction pressure to the discharge pressure. 
     The motor assembly  320  may be disposed within the suction chamber  328  and may include a motor stator  408  and a rotor  412 . The motor stator  408  may be attached to the shell body  322  (e.g., via press fit, staking, and/or welding). The rotor  412  may be attached to the shaft portion  378  of the driveshaft  368  (e.g., via press fit, staking, and/or welding). The driveshaft  368  may be driven by the rotor  412  for rotation relative to the shell assembly  312  about the first rotational axis A 1 . The motor assembly  320  could be a fixed-speed motor, a multi-speed motor or a variable-speed motor. 
     Referring to  FIG.  6   , during compressor operation, a working fluid enters the inlet of the compressor  300  through the suction inlet fitting  330  (Arrow A). The working fluid may include both a refrigerant and an oil (for example, an oil mist). Since the compressor  300  is a sumpless compressor, the oil for lubrication of moving parts travels with the working fluid through the compressor  300 . For example, the refrigerant may include, but is not limited to, one or more of R410a, R290, R744, R32 R454b, R134a, 404A, 407A/C/F, 507, and R717. For example, the oil may include, but is not limited to, one or more of Mineral Oil, Alkyl Benzene, Polyol Ester, and Polyalkylene glycol, as a few examples. 
     The working fluid, at suction pressure, is pulled into the one or more apertures  384  defining a suction passage within the driveshaft  368 . The working fluid moves through the driveshaft  368  towards the compression mechanism  318  (Arrow A). The working fluid travels through an output  416  of the aperture  384  and into the passage  391  defined by the space between the hub  380  and the first end plate  388  of the first scroll member  370  (Arrow B). A portion of the suction gas flowing through the passage  391  may exit into the suction pressure-chamber  328 . 
     The portion of the working fluid pulled into the suction pressure chamber  328  is circulated through the motor assembly  320  to cool the motor assembly  320  (Arrows C). For example, the working fluid is circulated through the stator  408  and rotor  412  to absorb heat generated by operation of the rotor  412  and cool the motor assembly  320 . 
     The main portion of the working fluid is received in the suction inlet opening  386  from the passage  391  (Arrow D). The suction inlet opening  386  in the compression mechanism  318  is an axially extending passage that extends perpendicularly from the passage  391 . The working fluid is compressed within the pockets defined by the first spiral wrap  390  of the first, driving scroll  370  and the second spiral wrap  394  of the second, driven scroll  372  (Arrow E). 
     The compressed working fluid is discharged through the discharge passage  398  in the second end plate  392  of the second, driven scroll  372  (Arrow F). The compressed working fluid is at a high-pressure (i.e., compression pressure) and flows through the discharge passage  398  in the stationary bearing support member  338 . The sealing assembly  365  isolates the compressed, high-pressure working fluid from the low-pressure suction pressure chamber  328 . The compressed working fluid exits the compressor  300  through the discharge outlet fitting  332  (Arrow G). 
     In an alternative example, the compressor  300  may include an impeller (not shown), similar to impeller  204  in compressor  200 , disposed between the hub  380  and the first end plate  388  of the first scroll  370 , which defines the suction plenum. The impeller may define a passage, similar to the passage  391 , that extends from the aperture  384  to the suction inlet opening  386  to streamline the gas flow from the aperture  384  to the suction inlet opening  386 . The streamlined flow may reduce pressure drops between the aperture  384  and the compression mechanism  318 . Additionally, the impeller provides pre-compression of the working fluid, where the working fluid is dynamically compressed prior to the compression mechanism  318  utilizing a centrifugal effect. The streamlined flow may, in certain conditions, provide a supercharging effect. 
     As described with respect to impeller  204 , the impeller may be formed of a thermally insulated material. For example, the thermally insulated material may include, but is not limited to, ceramics, silicone, thermal insulating sprays, plastics, ceramics, or graphite. The thermally insulating impeller may reduce the heat transfer into the refrigerant flowing through the passage  391  toward the suction inlet opening  386 . Reduction in the heat transfer may improve the volumetric efficiency of the refrigerant. 
     The impeller may be formed integrally with the first end plate  388  of the first scroll member  370  to create a single, monolithic piece. Accordingly, the position of the impeller relative to the first scroll member  370  may be fixed. Further, forming the impeller with the first end plate  388  creates easier and more reliable assembly of the compressor  300 . Alternatively, the impeller may fit within a recessed portion in the first end plate  388  of the first scroll member  370 . The recessed portion may locate and fix the position of the impeller relative to the hub  380  and the first scroll member  370 . 
     Alternatively, the impeller may be formed integrally with the hub  380  or with the driveshaft  368 . 
     During compressor  300  operation, the working fluid, at suction pressure, moves through the driveshaft  368  towards the compression mechanism  318 . The working fluid travels through an output  416  of the suction passage  384  and into the passage defined by the impeller. A portion of the suction gas flowing through the passage may exit into the suction pressure-chamber  328 . The main portion of the working fluid is received in the suction inlet opening  386  from the passage defined by the impeller. The working fluid is compressed within the pockets defined by the first spiral wrap  390  of the first, driving scroll  370  and the second spiral wrap  394  of the second, driven scroll  372 . 
     Referring now to  FIGS.  9  and  10   , an example compressor  500  is provided that may include a shell assembly  512 , a first bearing housing  514 , a second bearing housing  516 , a compression mechanism  518 , and a motor assembly  520 . The shell assembly  512  may include a shell body  522 , a first end cap  523 , and a second end cap  524 . The shell body  522  may be generally cylindrical. The first and second end caps  523 ,  524  may be fixedly attached to opposing axial ends of the shell body  522 . 
     The first end cap  523 , the shell body  522 , and the second end cap  524  may cooperate to define a discharge chamber  528 . The first and second bearing housings  514 ,  516 , the compression mechanism  518 , and the motor assembly  520  may be disposed within the discharge chamber  528 . The discharge chamber  528  may receive discharge-pressure working fluid from compression mechanism  518 . That is, discharge-pressure working fluid (i.e., high-pressure working fluid) may enter the discharge chamber  528  from the compression mechanism  518 . The compression mechanism  518  receives suction working fluid (i.e., suction-pressure working fluid at a lower pressure than discharge pressure) from a suction fitting  532  attached to the first end cap  523 . For example, the compression mechanism  518  is in direct communication with the suction fitting  532 , or compressor inlet, without use of a suction chamber. The discharge chamber  528  releases fluid from the compressor  500  through a discharge fitting  526  attached to the first end cap  523 . 
     The compressor  500  shown in the figures is a high-side compressor (i.e., the motor assembly  520  and at least a majority of the compression mechanism  518  are disposed in the discharge chamber  528 ). It will be appreciated, however, that the principles of the present disclosure are applicable to low-side compressors (i.e., compressors having the compression mechanism  518  disposed in a suction chamber). 
     The first bearing housing  514  may include a first bearing support member  538  and a second bearing support member  540 . The first bearing support member  538  may be a generally cylindrical shaft or body having a discharge passage  542  extending axially therethrough. The first bearing support member  538  may be fixed relative to the shell assembly  512 , forming a stationary shaft. For example, the first bearing support member  538  may be fixedly attached to the second end cap  524 . In other configurations, the first bearing support member  538  could be integrally formed with the second end cap  524 . The discharge passage  542  is in fluid communication with the discharge outlet fitting  526  and the compression mechanism  518  such that compressed working fluid discharged from the compression mechanism  518  flows through the discharge passage  542  and exits the discharge passage  542  through a first series of apertures, or slots,  544  at a proximal end of the discharge passage  542 , near the compression mechanism  518  and through a second series of apertures, or slots,  545  at a distal end of the discharge passage  542 , near the second end cap  524 . 
     The first bearing support member  538  includes a first cylindrical surface  546  and a second cylindrical surface  548 . The first cylindrical surface  546  may support a first bearing  550  and may define a first rotational axis A 1 . The second cylindrical surface  548  is eccentric relative to the first cylindrical surface  546  and defines a second rotational axis A 2  that is parallel to and laterally offset from the first rotational axis A 1 . The second cylindrical surface  548  supports a second bearing  552 . 
     The first and second bearings  550 ,  552  may be rolling element bearings that each may include an outer ring  554 , an inner ring  556 , and a plurality of rolling elements (e.g., spheres or cylinders)  558  disposed between the outer and inner rings  554 ,  556 . The inner ring  556  of the first bearing  550  may be fixedly attached to the first cylindrical surface  546  of the first bearing support member  538 . The outer ring  554  of the first bearing  550  may be attached to the second bearing support member  540 . The inner ring  556  of the second bearing  552  may be fixedly attached to the second cylindrical surface  548  of the first bearing support member  538 . The outer ring  554  of the second bearing  552  may be attached to the compression mechanism  518  (as will be described in more detail below). 
     Alternatively, the second bearing  552  may be attached to the first bearing support member  538  or the compression mechanism  518  to provide radial compliance. Radial compliance would allow the second bearing  552  to separate sideways from the first bearing support member  538  or the compression mechanism  518 , which may allow debris to pass through and improve durability and reliability. For example, the second bearing  552  may be arranged to provide radial compliance similarly or identically to the bearing disclosed in Assignee&#39;s commonly owned U.S. Publication No. 2021/0148362, the disclosure of which is incorporated by reference. 
     The second bearing support member  540  may be an annular member having a first cavity  541  and a second cavity  543 . The first cavity  541  may receive the first bearing  550 . The second cavity  543  may receive a portion of the compression mechanism  518 . The second bearing support member  540  may include a plurality of slots (not shown). For example, the slots may be formed in an axially facing surface  563  (i.e., a surface that faces a direction parallel to the direction in which axes A 1 , A 2  extend) of the second bearing support member  540 . 
     Counter to the compressor  300  including the annular seal  365  that sealingly engages the second bearing support member  340  and the first bearing support member  338 , the compressor  500  may not include seals along the first bearing support member  338  such that compressed working fluid (i.e., working fluid discharged from the compression mechanism  518 ) may flow from the discharge passage  542 , through the first series of apertures  544  and the second series of apertures  545 , and into the discharge chamber  528 . 
     The second bearing housing  516  may include an annular central hub  560 . The hub  560  receives a third bearing  562 . The hub  560  may also include a central aperture  564 . An annular seal  566  may be disposed within the hub  560  to prevent suction-pressure working fluid (i.e., working fluid from the suction inlet) from flowing into the discharge chamber  528 . For example, the annular seal  566  may be pressed into the hub  560  of the second bearing housing  516  and may separate the third bearing  562  from the discharge chamber  528 . 
     The compression mechanism  518  may include a driveshaft  568 , a first scroll member  570 , the second scroll member  572 , and an Oldham coupling (or Oldham ring)  576 . The first and second scroll members  570 ,  572  cooperate to define fluid pockets (i.e., compression pockets) therebetween. The compression mechanism  518  is a co-rotating scroll compression mechanism in which the first scroll member  570  is a driven scroll member and the second scroll member  572  is an idler scroll member. 
     The driveshaft  568  may include a shaft portion  578  and a hub  580 . The shaft portion  578  is rotatably supported by the third bearing  562  and extends through the motor assembly  520 . For example, the annular seal  566  may seal against shaft  578  and be press fit within the hub  560 . The hub  580  extends radially outward from an axial end of the shaft portion  578 . Fasteners  582  may extend through apertures in the hub  580 , the first scroll member  570 , and the second bearing support member  540  to rotationally fix the first scroll member  570  and the second bearing support member  540  relative to the driveshaft  568  (i.e., so that the first scroll member  570  and second bearing support member  540  rotate with the driveshaft  568  about the first rotational axis A 1 ). The driveshaft  568  may include one or more apertures  584  through which suction-pressure working fluid can flow into a suction inlet opening  586  in the first scroll member  570 . The suction inlet opening  586  may be an axially extending passage that terminates in a suction inlet  587  in the first scroll member  570 . The one or more apertures  584  define a suction passage in the driveshaft  568 . 
     The first scroll member  570  may include a first end plate  588  and a first spiral wrap  590  extending from the first end plate  588 . The suction inlet opening  586  may be disposed in the first end plate  588 . The suction inlet opening  586  may be in fluid communication with the aperture  584  through a passage  591  defined by a space between the first end plate  588  and the hub  580 . The passage  591  may be a radially extending passage that extends perpendicular to the aperture  584 . 
     The second scroll member  572  may include a second end plate  592 , a second spiral wrap  594  extending from one side of the second end plate  592 , and a hub  596  extending from the opposite side of the second end plate  592 . The second end plate  592  may include a discharge passage  598  that is in fluid communication with the discharge passage  542  in the first bearing support member  538 . 
     The second scroll member  572  may be disposed within the second cavity  543  of the second bearing support member  540 . The eccentric second cylindrical surface  548  of the first bearing support member  538  may be received within the hub  596  of the second scroll member  572 . The hub  596  of the second scroll member  572  may be rotatably supported by the second bearing  552  and the eccentric second cylindrical surface  548  of the first bearing support member  538 . In this manner, the second scroll member  572  is rotatable about the second rotational axis A 2 . As shown in  FIG.  10   , the second end plate  592  of the second scroll member  572  includes a plurality of slots  600 . 
     As will be described in more detail below, the Oldham coupling  576  may be keyed to the second bearing support member  540  and the second scroll member  572 . The Oldham coupling  576  transmits rotational energy of the driveshaft  568 , first scroll member  570  and second bearing support member  540  to the second scroll member  572  such that rotation of the driveshaft  568 , first scroll member  570  and second bearing support member  540  about the first rotational axis A 1  causes corresponding rotation of the second scroll member  572  about the second rotational axis A 2 . The first and second spiral wraps  590 ,  594  are intermeshed with each other and cooperate to form a plurality of fluid pockets (i.e., compression pockets) therebetween. Rotation of the first scroll member  570  about the first rotational axis A 1  and rotation of the second scroll member  572  about the second rotational axis A 2  causes the fluid pockets to decrease in size as they move from a radially outer position to a radially inner position, thereby compressing the working fluid therein from the suction pressure to the discharge pressure. 
     The motor assembly  520  may be disposed within the discharge chamber  528  and may include a motor stator  602  and a rotor  604 . The motor stator  602  may be attached to the shell body  522  (e.g., via press fit, staking, and/or welding). The rotor  604  may be attached to the shaft portion  578  of the driveshaft  568  (e.g., via press fit, staking, and/or welding). The driveshaft  568  may be driven by the rotor  604  for rotation relative to the shell assembly  512  about the first rotational axis A 1 . The motor assembly  520  could be a fixed-speed motor, a multi-speed motor or a variable-speed motor. 
     Referring to  FIG.  9   , during compressor operation, a working fluid enters an inlet  608  of the compressor  500  through the suction inlet fitting  532  (Arrow A). The working fluid may include both a refrigerant and an oil (for example, an oil mist). Since the compressor  500  is a sumpless compressor, the oil for heat transfer and lubrication of moving parts travels with the working fluid through the compressor  500 . For example, the refrigerant may include, but is not limited to, one or more of R410a, R290, R744, R32 R454b, R134a, 404A, 407A/C/F, 507, and R717. For example, the oil may include, but is not limited to, one or more of Mineral Oil, Alkyl Benzene, Polyol Ester, and Polyalkylene glycol, as a few examples. 
     The working fluid, at suction pressure, is pulled into the one or more apertures  584  defining a suction passage within the driveshaft  568 . Because the annular seal  566  is provided in the hub  560  of the second bearing housing  516 , the discharge-pressure working fluid does not leak into the suction stream at arrow A. Instead, the suction-pressure working fluid travels from the suction inlet fitting  532  directly through the aperture  584  in the driveshaft  568 . The working fluid moves through the driveshaft  568  towards the compression mechanism  518  (Arrow A). The working fluid travels through an output  612  of the aperture  584  and into the passage  591  defined by the space between the hub  580  and the first end plate  588  of the first scroll member  570  (Arrow B). Unlike the compressor  300 , a portion of the suction gas flowing through the passage  584  does not exit into the discharge pressure-chamber  528 . Instead, in compressor  500 , all of the suction gas flowing through the passage  584  is directed into the compression mechanism  518 . 
     The working fluid is received in the suction inlet opening  586  from the passage  591  (Arrow C). The suction inlet opening  586  in the compression mechanism  518  is an axially extending passage that extends perpendicularly from the passage  591 . The suction inlet opening  586  terminates at the suction inlet  587  in the first scroll member  570 . The working fluid is compressed within the pockets defined by the first spiral wrap  590  of the first, driving scroll member  570  and the second spiral wrap  594  of the second, driven scroll member  572  (Arrow D). 
     The compressed working fluid is discharged through the discharge passage  598  in the second end plate  592  of the second, driven scroll  572  (Arrow E). A portion of the compressed working fluid exits into the discharge pressure chamber  528  before entering the discharge passage  542  in the stationary bearing support member  538  (Arrow F). The exiting portion of the compressed working fluid passes through the second bearing  552  and the first bearing  550 , in that order. 
     The main portion of the compressed working fluid is at a high-pressure (i.e., compression pressure) and flows through the discharge passage  542  in the stationary bearing support member  538  (Arrow G). The compressed working fluid exits into the discharge pressure chamber  528  through at least one aperture  545  in a distal end of the stationary bearing support member  538  (Arrow H). 
     A portion of the working fluid in the discharge pressure chamber  528  is circulated through the motor assembly  520  to cool the motor assembly  520  (Arrows J). For example, the working fluid is circulated through the stator  602  and rotor  604  to absorb heat generated by operation of the stator  602  and rotor  604  and cool the motor assembly  520 . 
     Another portion of the working fluid in the discharge pressure chamber  528  may bypass the motor assembly  520 , passing between the motor assembly  520  and the shell  512  (Arrow K). The compressed working fluid exits the compressor  500  through the discharge outlet fitting  526  (Arrow L). 
     In an alternative example, the compressor  500  may include an impeller (not shown), similar to impeller  204  in compressor  200 , disposed between the hub  580  and the first end plate  588  of the first scroll  570 , which defines the suction plenum. The impeller may define a passage, similar to the passage  591 , that extends from the aperture  584  to the suction inlet opening  586  to streamline the gas flow from the aperture  584  to the suction inlet opening  586 . The streamlined flow may reduce pressure drops between the aperture  584  and the compression mechanism  518 . Additionally, the impeller provides pre-compression of the working fluid, where the working fluid is dynamically compressed prior to the compression mechanism  518  utilizing a centrifugal effect. The streamlined flow may, in certain conditions, provide a supercharging effect. 
     As described with respect to impeller  204 , the impeller may be formed of a thermally insulated material. For example, the thermally insulated material may include, but is not limited to, ceramics, silicone, thermal insulating sprays, plastics, ceramics, or graphite. The thermally insulating impeller may reduce the heat transfer into the refrigerant flowing through the passage toward the suction inlet opening  586 . Reduction in the heat transfer may improve the volumetric efficiency of the refrigerant. 
     The impeller may be formed integrally with the first end plate  588  of the first scroll member  570  to create a single, monolithic piece. Accordingly, the position of the impeller relative to the first scroll member  570  may be fixed. Further, forming the impeller with the first end plate  588  creates easier and more reliable assembly of the compressor  500 . Alternatively, the impeller may fit within a recessed portion in the first end plate  588  of the first scroll member  570 . The recessed portion may locate and fix the position of the impeller relative to the hub  580  and the first scroll member  570 . Alternatively, the impeller may be formed integrally with the hub  580  or with the driveshaft  568 . 
     During compressor  500  operation, the working fluid, at suction pressure, moves through the driveshaft  568  towards the compression mechanism  518 . The working fluid travels through the output  612  of the suction passage  584  and into the passage defined by the impeller. The working fluid is received in the suction inlet opening  586  from the passage defined by the impeller. The working fluid is compressed within the pockets defined by the first spiral wrap  590  of the first, driving scroll  570  and the second spiral wrap  594  of the second, driven scroll  572 . 
     Now referring to  FIGS.  11  and  12   , a compressor  700  is provided that may include a hermetic shell assembly  712 , a bearing housing assembly  714 , a motor assembly  716 , and a compression mechanism  718 . 
     The shell assembly  712  may generally form a compressor housing and may include a cylindrical shell  722 , a first end cap  724  at one end of the shell  722 , a partition  725 , and a second end cap  726  at another end of the shell  722 . The first end cap  724 , the shell  722 , and the partition  725  may cooperate to define a suction-pressure chamber  730 . A suction gas inlet fitting  732  may be attached to the shell assembly  712  at an opening in the first end cap  724 . Suction-pressure working fluid (i.e., low-pressure working fluid) may be drawn into the compression mechanism  718  via the suction gas inlet fitting  732  for compression therein. 
     As shown in  FIGS.  11  and  12   , the partition  725  and the second end cap  726  may cooperate to define a discharge-pressure chamber  734 . The partition  725  may separate the discharge-pressure chamber  734  from the suction pressure chamber  730 . A discharge gas outlet fitting  735  may be attached to the shell assembly  712  at another opening in the second end cap  726  and may communicate with the discharge-pressure chamber  734 . Discharge-pressure working fluid (i.e., working fluid at a higher pressure than suction pressure) may be discharged by the compression mechanism  718  and may flow into the discharge-pressure chamber  734 . The discharge-pressure working fluid in the discharge-pressure chamber  734  may exit the compressor  700  through the discharge-gas-outlet fitting  735 . In some configurations, a discharge valve (e.g., a check valve) may be disposed within or adjacent the discharge-gas-outlet fitting  735  and may allow fluid to exit the discharge-pressure chamber  734  through the discharge-gas-outlet fitting  735  and prevent fluid from entering the discharge-pressure chamber  734  through the discharge-gas-outlet fitting  735 . 
     The compressor  700  shown in the figures is a co-rotating, low-side scroll compressor with integrated motor (i.e., the motor assembly  716  and at least a majority of the compression mechanism  718  are at suction pressure). It will be appreciated, however, that the principles of the present disclosure are applicable to high-side compressors (i.e., compressors having the compression mechanism  718  disposed at discharge pressure). 
     The bearing housing assembly  714  may be disposed within the suction pressure chamber  730  and may include a main bearing housing  738 . The main bearing housing  738  may include a first bearing support member  748  and a second bearing support member  752 . The first bearing support member  748  may be a generally cylindrical shaft or body having a discharge passage  756  extending axially therethrough. The first bearing support member  748  may be fixed relative to the shell assembly  712 , forming a stationary shaft. For example, the first bearing support member  748  may be fixedly attached to the partition  725  and may be in fluid communication with the discharge chamber  734 . In other configurations, the first bearing support member  748  could be integrally formed with the partition  725 . The discharge passage  756  is in fluid communication with the discharge chamber  734  and the compression mechanism  718  such that compressed working fluid discharged from the compression mechanism  718  flows through the discharge passage  756  and exits the discharge passage  756  at a distal end of the discharge passage  756 , near the partition  725 . 
     The first bearing support member  748  includes a first cylindrical surface  768  and a second cylindrical surface  772 . The first cylindrical surface  768  may support a first bearing  776  and may define a first rotational axis A 1 . The second cylindrical surface  772  is eccentric relative to the first cylindrical surface  768  and defines a second rotational axis A 2  that is parallel to and laterally offset from (i.e., non-collinear with) the first rotational axis A 1 . The second cylindrical surface  772  supports a second bearing  780 . 
     The first and second bearings  776 ,  780  may be rolling element bearings that each may include an outer ring  784 , an inner ring  788 , and a plurality of rolling elements (e.g., spheres or cylinders)  792  disposed between the outer and inner rings  784 ,  788 . The inner ring  788  of the first bearing  776  may be fixedly attached to the first cylindrical surface  768  of the first bearing support member  748 . The outer ring  784  of the first bearing  776  may be attached to the second bearing support member  752 . The inner ring  788  of the second bearing  780  may be fixedly attached to the second cylindrical surface  772  of the first bearing support member  748  or alternatively, positioned over the second cylindrical surface  772  with a radial clearance to achieve radial compliance. The outer ring  784  of the second bearing  780  may be attached to the compression mechanism  718  (as will be described in more detail below). Alternatively, the second bearing  780  may be attached to the first bearing support member  748  or the compression mechanism  718  to provide radial compliance. Radial compliance would allow the second bearing  780  to separate sideways from the first bearing support member  748  or the compression mechanism  718 , which may allow debris to pass through and improve durability and reliability. 
     The second bearing support member  752  may be an annular member having a first cavity  796  and a second cavity  800 . The first cavity  796  may receive the first bearing  776 . The second cavity  800  may receive a portion of the compression mechanism  718  and the second bearing  780 . The second bearing support member  752  may include a plurality of slots  804  ( FIG.  12   ). For example, the slots  804  may be formed in an axially facing surface  808  (i.e., a surface that faces a direction parallel to the direction in which axes A 1 , A 2  extend) of the second bearing support member  752 . An annular seal  812  may be disposed within the second bearing support member  752  (e.g., axially between the first and second cavities  796 ,  800 ). The seal  812  may sealingly engage the second bearing support member  752  and the first bearing support member  748 . The seal  812  may include a housing  813  and a sealing member  814 . The housing  813  is press-fitted within the second bearing support member  752  such that an outer diametrical surface of the housing  813  is sealingly engaged with an inner diametrical surface of the second bearing support member  752 . The sealing member  814  is disposed within the housing  813  and is sealingly engaged with an outer diametrical surface of the first bearing support member  748 . In this way, fluid discharged from the fluid pockets of the compression mechanism  718  is prevented from flowing to the bearing  776  and to the suction pressure chamber  730 . 
     Another annular seal  816  sealingly engages the second bearing support member  752  and a second scroll member  820 . Seal  816  may be disposed within a groove  817  formed in the second bearing support member  752  and may sealingly and slidably engage the second scroll member  820  to form an annular biasing chamber  731 . The seal  816  keeps the biasing chamber  731  sealed off from discharge fluid while still allowing relative movement between the second bearing support member  752  and the second scroll member  820 . 
     The first end cap  724  may include a second bearing housing  824 . The second bearing housing  824  may be fixed to the first end cap  724 . Alternatively, the second bearing housing  824  may be formed integrally and monolithically with the end cap  724 . The second bearing housing  824  may include an annular central hub  828 . The hub  828  may project from an internal surface  832  of the first end cap  724 . The hub  828  receives a third bearing  836 . 
     The third bearing  836  may be a rolling element bearing that may include an outer ring  848 , an inner ring  852 , and a plurality of rolling elements (e.g., spheres or cylinders)  856  disposed between the outer and inner rings  848 ,  852 . The inner ring  848  may be fixedly attached to a cylindrical surface  860  of a driveshaft  864 . The outer ring  848  may be attached to the hub  828 . 
     The compression mechanism  718  may include the driveshaft  864 . The compression mechanism  718  may be disposed within the suction pressure chamber  730 . The compression mechanism  718  may include a first compression member and a second compression member that cooperate to define fluid pockets (i.e., compression pockets) therebetween. For example, the compression mechanism  718  may be a co-rotating scroll compression mechanism in which the first compression member is a first scroll member (i.e., a driver scroll member)  868  and the second compression member is the second scroll member (i.e., a driven scroll member)  820 . 
     The driveshaft  864  may include a shaft section  872  and a hub  876 . The shaft section  872  may include a suction passage  880 . The suction passage  880  provides fluid communication between the suction gas inlet fitting  732  and the compression mechanism  718 . An inlet  884  of the suction passage  880  may be disposed at or near a first end  888  of the shaft section  872  adjacent the suction gas inlet fitting  732  or the suction-pressure chamber  730 . An outlet  892  of the suction passage  880  may be disposed at or near a second end  896  of the shaft section  872  adjacent to the compression mechanism  718 . The second end  896  of the shaft section  872  may include a flange  900  for engaging the shaft section  872  with the hub  876 . The suction passage  880  may be coated in a thermal insulation coating to prevent preheat of the working fluid. For example, the thermal insulation coating may include, but is not limited to, ceramics, silicone or thermal insulating sprays. 
     A radial portion  904  of the hub  876  may engage with the second end  896  of the shaft section  872 . The hub  876  may further include an axial portion  908  and a flange  916 . The radial portion  904  extends in a radial direction from the second end  896  of the shaft section  872  (in a direction perpendicular to a rotational axis A 1  of driveshaft  864 ) and the axial portion  908  extends in an axial direction from a periphery of the radial portion  904  (in a direction parallel to a rotational axis A 1  of driveshaft  864 ). The flange  916  extends in a radial direction from an end of the axial portion  908  and includes a plurality of pin housings  920 . As shown in  FIG.  12   , the pin housings  920  are spaced apart from each other and are circumferentially disposed around the flange  916 . Each pin  924  extending from the main bearing housing  738  is received in a respective pin housing  920 , thereby coupling the main bearing housing  738  and the hub  876  to each other. In this manner, rotation of the main bearing housing  738  causes corresponding rotation of the driveshaft  864  about the rotational axis A 1  of the driveshaft  864 . 
     The first scroll member  868  may include a first end plate  928  and a first spiral wrap  932  extending from the first end plate  928 . The first end plate  928  is disposed within and fixed to the flange  916  of the driveshaft  864  such that the flange  916  surrounds the first spiral wrap  928 . In some configurations, the first scroll member  868  and the driveshaft  864  may be a single component as opposed to two separate components fixed to each other. The first end plate  928  may include an axially extending passage  936 . A radially extending passage  940  is formed between the first end plate  928  and the hub  876  and extends from the outlet  892  of the suction passage  880  to the axially extending passage  936 . The axially extending passage  936  extends from an end of the radially extending passage  940  to a suction inlet  944  of the first scroll member  868 . In this way, suction gas flowing through the suction passage  880  may flow through the passages  936 ,  940  and into an outermost pocket of the fluid pockets via the suction inlet  944 . A portion of the suction gas flowing through the passages  936 ,  940  may exit into the suction pressure chamber  730 . 
     The second scroll member  820  defines a second rotational axis A 2  that is parallel to the rotational axis A 1  and offset from the rotational axis A 1 . The second scroll member  820  may include a second end plate  948 , a cylindrical hub  952  extending from one side of the second end plate  948 , and a second spiral wrap  956  extending from the opposite side of the second end plate  948 . 
     The first bearing support member  748  may form a stationary crank having the discharge passage  756 . The proximal end of the first bearing support member  748  may extend through the bearing  780  and into the hub  952 . The passage  756  provides fluid communication between the compression mechanism  718  and the discharge-pressure chamber  734 . The discharge passage  756  may be coated with a thermal insulation coating to prevent heat transfer from the compressed working fluid to the compressor parts. For example, the thermal insulation coating may include, but is not limited to, ceramics, silicone or thermal insulating sprays. 
     The first and second spiral wraps  932 ,  956  are intermeshed with each other and cooperate to form a plurality of fluid pockets (i.e., compression pockets) therebetween. Rotation of the first scroll member  868  about the rotational axis A 1  and rotation of the second scroll member  820  about the second rotational axis A 2  causes the fluid pockets to decrease in size as they move from a radially outer position to a radially inner position, thereby compressing the working fluid therein from the suction pressure to the discharge pressure. 
     The second end plate  948  may be disposed axially between the first end plate  928  and the main bearing housing  738 . The second end plate  948  may include a biasing passage (not shown) that provides fluid communication between an intermediate-pressure compression pocket and the biasing chamber. 
     The second end plate  948  may include a discharge passage  960 . The discharge passage  960  extends through the second end plate  948  and provides fluid communication between a radially innermost one of the fluid pockets and the discharge-gas-outlet fitting  735  (via the passage  756  in the first bearing support member  748 ). A discharge valve (e.g., a reed valve or other check valve) may be disposed within or adjacent the discharge passage  960  or at the proximal end of the first bearing support member  748 . The discharge valve allows working fluid to be discharged from the compression mechanism  718  through the discharge passage  960  and into the first bearing support member  748  and prevents working fluid in the first bearing support member  748  from flowing back into to the compression mechanism  718 . The discharge gas flowing out of the discharge passage  960  may flow through the passage  756  of the first bearing support member  748 , into the discharge-pressure chamber  734  and out of the compressor  700  through the discharge-gas-outlet fitting  735 . 
     The motor assembly  716  may be disposed within the suction pressure chamber  730  and may include a motor stator  964  and a rotor  968 . The motor stator  964  may be attached to the shell  722  (e.g., via press fit, staking, and/or welding). The rotor  968  may be attached to the second bearing support member  752  (e.g., via press fit, staking, epoxy, glue, adhesive, and/or welding). The second bearing support member  752  may be driven by the rotor  968  and may be supported by bearings  776  and  836  for rotation relative to the shell assembly  712 . The bearing  776  may be fixed to the first bearing support member  748  and the second bearing support member  752 . The bearing  836  may be fixed to the second bearing housing  824  and the driveshaft  864 . In some configurations, the motor assembly  716  is a variable-speed motor. In other configurations, the motor assembly  716  could be a multi-speed motor or a fixed-speed motor. 
     Attaching the motor stator  964  to the shell  722  and the rotor  968  to the second bearing support member  752  positions the motor assembly  716  about the second bearing support member  752 , instead of about the driveshaft  864 . Placement of the motor assembly  716  about the second bearing support member  752  reduces the compressor  700  footprint. The shaft section  872  of the driveshaft  864  may be reduced in length, reducing an overall length of the compressor  700 . A reduction in the footprint of the compressor  700  reduces the thermal communication of the suction gas with other parts of the compressor  700 , reducing pre-heat. 
     Following the arrows in  FIG.  11   , during use, a working fluid enters the compressor  700  through the suction gas inlet fitting  732  in the first end cap  724  of the compressor  700  (Arrow A). The working fluid may include both a refrigerant and an oil (for example, an oil mist). Since the compressor  700  is a sumpless compressor, the oil for heat transfer and lubrication of moving parts travels with the working fluid through the compressor  700 . For example, the refrigerant may include, but is not limited to, one or more of R410a, R290, R744, R32 R454b, R134a, 404A, 407A/C/F, 507, and R717. For example, the oil may include, but is not limited to, one or more of Mineral Oil, Alkyl Benzene, Polyol Ester, and Polyalkylene glycol, as a few examples. 
     The working fluid, at suction pressure, enters the suction passage  880  within the driveshaft  864 . A portion of the working fluid, at suction pressure enters the suction pressure chamber  730  through the bearing  836  in the second bearing housing  824 . The portion of the working fluid in the suction pressure chamber  730  may circulate through the motor assembly  716  to transfer heat away from the motor assembly  716  and cool the rotor  968  and stator  964  (Arrow B). 
     A main portion of the working fluid, at suction pressure, is pulled through the suction passage  880  within the driveshaft  864  (Arrow A). The working fluid moves through the driveshaft  864  towards the compression mechanism  718 . The working fluid travels through the output  892  of the suction passage  880  and into the radially extending passage  940  defined by the space between the hub  876  and the first end plate  928  (Arrow C). A portion of the suction gas flowing through the passages  880 ,  940  may exit into the suction pressure chamber  730 . 
     The working fluid is received in the axially extending passage  936  from the radially extending passage  940  (Arrow D). The axially extending passage  936  provides an entrance into the suction inlet  944  in the compression mechanism  718 . The working fluid is compressed within the pockets defined by the first spiral wrap  932  of the first, driving scroll  868  and the second spiral wrap  956  of the second, driven scroll  820  (Arrow E). 
     The compressed working fluid is discharged through the discharge passage  960  in the second end plate  948  of the second, driven scroll  820  (Arrow F). The compressed working fluid is at a high-pressure (i.e., discharge pressure) and flows through the discharge passage  756  in the first bearing support member  748 . The annular seals  812 ,  816  isolate the compressed, high-pressure working fluid from the suction pressure chamber  730  and intermediate chamber  731 . The compressed working fluid enters the discharge-pressure chamber  734  (Arrow G). The compressed working fluid exits the compressor  700  through the discharge gas outlet fitting  735  (Arrow H). 
     In an alternative example, the compressor  700  may include an impeller (not shown), similar to impeller  204  in compressor  200 , disposed between the flange  900  and the first end plate  928  of the first scroll member  868 , which defines the suction plenum. The impeller may define a passage, similar to the passage  940 , which extends from the output  892  to the axially extending passage  936 , to streamline the gas flow from the output  892  to the axially extending passage  936 . The streamlined flow may reduce pressure drops between the output  892  and the compression mechanism  718 . Additionally, the impeller provides pre-compression of the working fluid, where the working fluid is dynamically compressed prior to the compression mechanism  718  utilizing a centrifugal effect. The streamlined flow may, in certain conditions, provide a supercharging effect. 
     As described with respect to impeller  204 , the impeller may be formed of a thermally insulated material. For example, the thermally insulated material may include, but is not limited to, ceramics, silicone, thermal insulating sprays, plastics, ceramics, or graphite. The thermally insulating impeller may reduce the heat transfer into the refrigerant flowing through the passage in the impeller toward the axially extending passage  936  and compression mechanism  718 . Reduction in the heat transfer may improve the volumetric efficiency of the refrigerant. 
     The impeller may be formed integrally with the first end plate  928  of the first scroll member  868  to create a single, monolithic piece. Accordingly, the position of the impeller relative to the first scroll member  868  may be fixed. Further, forming the impeller with the first end plate  928  creates easier and more reliable assembly of the compressor  700 . Alternatively, the impeller may fit within a recessed portion in the first end plate  928  of the first scroll member  868 . The recessed portion may locate and fix the position of the impeller relative to the flange  900  and the first scroll member  868 . Alternatively, the impeller may be formed integrally with the hub  876  or with the driveshaft  864 . 
     During compressor  700  operation, the working fluid, at suction pressure, moves through the driveshaft  864  towards the compression mechanism  718 . The working fluid travels through an output  892  of the suction passage  880  and into the passage defined by the impeller. The working fluid is received in the axially extending passage  936  from the passage defined by the impeller. The working fluid is compressed within the pockets defined by the first spiral wrap  932  of the first, driving scroll  868  and the second spiral wrap  956  of the second, driven scroll  820 . 
     Now referring to  FIGS.  13  and  14   , a compressor  1000  is provided that may include a hermetic shell assembly  1012 , a bearing housing assembly  1014 , a motor assembly  1016 , and a compression mechanism  1018 . 
     The shell assembly  1012  may generally form a compressor housing and may include a cylindrical shell  1022 , a first end cap  1024  at one end of the shell  1022 , a partition  1025 , and a second end cap  1026  at another end of the shell  1022 . A suction gas inlet fitting  1032  may be attached to the shell assembly  1012  at an opening in the first end cap  1024 . Suction-pressure working fluid (i.e., low-pressure working fluid) may be drawn into the compression mechanism  1018  via the suction gas inlet fitting  1032  for compression therein. 
     As shown in  FIGS.  13  and  14   , the partition  1025 , the shell  1022 , and the first end cap  1024  may cooperate to define an internal space  1033 . The partition  1025  and the second end cap  1026  may cooperate to define a discharge-pressure chamber  1034 . The partition  1025  may include apertures  1031  ( FIG.  14   ) that fluidly connect the discharge-pressure chamber  1034  with the internal space  1033 . A discharge gas outlet fitting  1035  may be attached to the shell assembly  1012  at an opening in the second end cap  1026  and may communicate with the discharge-pressure chamber  1034 . Discharge-pressure working fluid (i.e. working fluid at a higher pressure than suction pressure) may be discharged by the compression mechanism  1018  and may flow into the discharge-pressure chamber  1034 . The discharge-pressure working fluid may flow into the internal space  1033  through the apertures  1031 , such that the internal space  1033  is at discharge pressure. The main portion of the discharge-pressure working fluid in the discharge-pressure chamber  1034  may exit the compressor  1000  through the discharge-gas-outlet fitting  1035 . 
     In some configurations, a discharge valve (e.g., a check valve) may be disposed within or adjacent the discharge-gas-outlet fitting  1035  and may allow fluid to exit the discharge-pressure chamber  1034  through the discharge-gas-outlet fitting  1035  and prevent fluid from entering the discharge-pressure chamber  1034  through the discharge-gas-outlet fitting  1035 . 
     The compressor  1000  shown in the figures is a co-rotating, high-side, integrated-scroll compressor (i.e., the motor assembly  1016  and at least a majority of the compression mechanism  1018  are at discharge pressure). It will be appreciated, however, that the principles of the present disclosure are applicable to low-side compressors (i.e., compressors having the compression mechanism  1018  disposed at suction pressure). 
     The bearing housing assembly  1014  may be disposed within the internal space  1033  (at discharge pressure) and may include a main bearing housing  1038 . The main bearing housing  1038  may include a first bearing support member  1048  and a second bearing support member  1052 . The first bearing support member  1048  may be a generally cylindrical shaft or body having a discharge passage  1056  extending axially therethrough. The first bearing support member  1048  may be fixed relative to the shell assembly  1012 , forming a stationary shaft. For example, the first bearing support member  1048  may be fixedly attached to the partition  1025  and may be in fluid communication with the discharge chamber  1034 . In other configurations, the first bearing support member  1048  could be integrally formed with the partition  1025 . The discharge passage  1056  is in fluid communication with the discharge chamber  1034 , the internal space  1033 , and the compression mechanism  1018  such that compressed working fluid discharged from the compression mechanism  1018  flows through the discharge passage  1056  and exits the discharge passage  1056  through a series of apertures, or slots,  1060  at a proximal end of the discharge passage  1056 , near the compression mechanism  1018  and through an aperture at a distal end of the discharge passage  1056 , near the partition  1025 . 
     The first bearing support member  1048  includes a first cylindrical surface  1068  and a second cylindrical surface  1072 . The first cylindrical surface  1068  may support a first bearing  1076  and may define a first rotational axis A 1 . The second cylindrical surface  1072  is eccentric relative to the first cylindrical surface  1068  and defines a second rotational axis A 2  that is parallel to and laterally offset from (i.e., non-collinear with) the first rotational axis A 1 . The second cylindrical surface  1072  supports a second bearing  1080 . 
     The first and second bearings  1076 ,  1080  may be rolling element bearings that each may include an outer ring  1084 , an inner ring  1088 , and a plurality of rolling elements (e.g., spheres or cylinders)  1092  disposed between the outer and inner rings  1084 ,  1088 . The inner ring  1088  of the first bearing  1076  may be fixedly attached to the first cylindrical surface  1068  of the first bearing support member  1048 . The outer ring  1084  of the first bearing  1076  may be attached to the second bearing support member  1052 . The inner ring  1088  of the second bearing  1080  may be fixedly attached to the second cylindrical surface  1072  of the first bearing support member  1048 . The outer ring  1084  of the second bearing  1080  may be attached to the compression mechanism  1018  (as will be described in more detail below). Alternatively, the second bearing  1080  may be attached to the first bearing support member  1048  or the compression mechanism  1018  to provide radial compliance. Radial compliance would allow the second bearing  1080  to separate sideways from the first bearing support member  1048  or the compression mechanism  1018 , which may allow debris to pass through and improve durability and reliability. 
     The second bearing support member  1052  may be an annular member having a first cavity  1096  and a second cavity  1100 . The first cavity  1096  may receive the first bearing  1076 . The second cavity  1100  may receive a portion of the compression mechanism  1018  and the second bearing  1080 . The second bearing support member  1052  may include a plurality of slots  1104  ( FIG.  14   ). For example, the slots  1104  may be formed in an axially facing surface  1108  (i.e., a surface that faces a direction parallel to the direction in which axes A 1 , A 2  extend) of the second bearing support member  1052 . 
     An annular seal  1116  sealingly engages the second bearing support member  1052  and a second scroll member  1120 . Seal  1116  may be disposed within a groove  1117  formed in the second bearing support member  1052  and may sealingly and slidably engage the second scroll member  1120  to form an annular biasing chamber  1118 . The seal  1116  keeps the biasing chamber  1118  sealed off from the internal space  1033  (at discharge pressure) and the discharge fluid while still allowing relative movement between the second bearing support member  1052  and the second scroll member  1120 . 
     The first end cap  1024  may include a second bearing housing  1124  formed integrally and monolithically therewith. The second bearing housing  1124  may include an annular central hub  1128 . The hub  1128  may project from an internal surface  1132  of the first end cap  1024 . The hub  1128  may define a suction-pressure chamber  1134 . The hub  1128  receives a third bearing  1136 . The hub  1128  may also include a central aperture  1140 . The hub  1128  may separate the suction-pressure chamber  1134  from an internal space  1033  defined by the shell  1022 . 
     The third bearing  1136  may be a rolling element bearing that may include an outer ring  1148 , an inner ring  1152 , and a plurality of rolling elements (e.g., spheres or cylinders)  1156  disposed between the outer and inner rings  1148 ,  1152 . The inner ring  1148  may be fixedly attached to a cylindrical surface  1160  of a driveshaft  1164 . The outer ring  1148  may be attached to the hub  1128 . 
     An annular seal  1166  may be disposed within the hub  1128 . The seal  1166  may sealingly engage the cylindrical surface  1160  and the hub  1128 . The seal  1166  is press-fitted within the hub  1128 . In this way, fluid is prevented from flowing to internal space  1033  (at discharge pressure). 
     The compression mechanism  1018  may include the driveshaft  1164 . The compression mechanism  1018  may be disposed within the internal space  1033  in fluid communication with the suction-pressure chamber  1134 . The compression mechanism  1018  may include a first compression member and a second compression member that cooperate to define fluid pockets (i.e., compression pockets) therebetween. For example, the compression mechanism  1018  may be a co-rotating scroll compression mechanism in which the first compression member is a first scroll member (i.e., a driver scroll member)  1168  and the second compression member is the second scroll member (i.e., a driven scroll member)  1120 . 
     The driveshaft  1164  may include a shaft section  1172  and a hub  1176 . The shaft section  1172  may include a suction passage  1180 . The suction passage  1180  provides fluid communication between the suction gas inlet fitting  1032  and the compression mechanism  1018 . An inlet  1184  of the suction passage  1180  may be disposed at or near a first end  1188  of the shaft section  1172  adjacent the suction gas inlet fitting  1032  or the suction-pressure chamber  1134 . An outlet  1192  of the suction passage  1180  may be disposed at or near a second end  1196  of the shaft section  1172  adjacent to the compression mechanism  1018 . The second end  1196  of the shaft section  1172  may include a flange  1200  for engaging the shaft section  1172  with the hub  1176 . The suction passage  1180  may be coated in a thermal insulation coating to prevent preheat of the working fluid. For example, the thermal insulation coating may include, but is not limited to, ceramics, silicone or thermal insulating sprays. 
     A radial portion  1204  of the hub  1176  may engage with the second end  1196  of the shaft section  1172 . More particularly, the flange  1200  on the second end  1196  of the shaft section  1172  may be fixed to the radial portion  1204  of the hub  1176 . The hub  1176  may further include an axial portion  1212  and a flange  1216 . The radial portion  1204  extends in a radial direction from the second end  1196  of the shaft section  1172  (in a direction perpendicular to a rotational axis A 1  of driveshaft  1164 ) and the axial portion  1212  extends in an axial direction from a periphery of the radial portion  1204  (in a direction parallel to a rotational axis A 1  of driveshaft  1164 ). The flange  1216  extends in a radial direction from an end of the axial portion  1212  and includes a plurality of pin housings  1220 . As shown in  FIG.  14   , the pin housings  1220  are spaced apart from each other and are circumferentially disposed around the flange  1216 . Each pin  1224  extends from a respective pin housing  1220  to the main bearing housing  1038 , thereby coupling the main bearing housing  1038  and the hub  1176  to each other. In this manner, rotation of the main bearing housing  1038  causes corresponding rotation of the driveshaft  1164  about the rotational axis A 1  of the driveshaft  1164 . 
     The first scroll member  1168  may include a first end plate  1228  and a first spiral wrap  1232  extending from the first end plate  1228 . The first end plate  1228  is disposed within and fixed to the flange  1216  of the driveshaft  1164  such that the flange  1216  surrounds the first spiral wrap  1232 . In some configurations, the first scroll member  1168  and the driveshaft  1164  may be a single component as opposed to two separate components fixed to each other. The first end plate  1228  may include an axially extending passage  1236  ( FIG.  14   ). A radially extending passage  1240  is formed between the first end plate  1228  and the hub  1176  and extends from the outlet  1192  of the suction passage  1180  to the axially extending passage  1236 . The axially extending passage  1236  extends from an end of the radially extending passage  1240  to a suction inlet  1244  of the first scroll member  1168 . In this way, suction gas flowing through the suction passage  1180  may flow through the passages  1236 ,  1240  and into an outermost pocket of the fluid pockets via the suction inlet  1244 . 
     The second scroll member  1120  defines a second rotational axis A 2  that is parallel to the rotational axis A 1  and offset from the rotational axis A 1 . The second scroll member  1120  may include a second end plate  1248 , a cylindrical hub  1252  extending from one side of the second end plate  1248 , and a second spiral wrap  1256  extending from the opposite side of the second end plate  1248 . 
     The first bearing support member  1048  may form a stationary crank shaft having the discharge passage  1056 . The proximal end of the first bearing support member  1048  may extend through the bearing  1080  and into the hub  1252 . The passage  1056  provides fluid communication between the compression mechanism  1018  and the discharge-pressure chamber  1034 . The discharge passage  1056  may be coated with a thermal insulation coating to prevent heat transfer from the compressed working fluid to the compressor parts. For example, the thermal insulation coating may include, but is not limited to, ceramics, silicone or thermal insulating sprays. 
     The first and second spiral wraps  1232 ,  1256  are intermeshed with each other and cooperate to form a plurality of fluid pockets (i.e., compression pockets) therebetween. Rotation of the first scroll member  1168  about the rotational axis A 1  and rotation of the second scroll member  1120  about the second rotational axis A 2  causes the fluid pockets to decrease in size as they move from a radially outer position to a radially inner position, thereby compressing the working fluid therein from the suction pressure to the discharge pressure. 
     The second end plate  1248  may be disposed axially between the first end plate  1228  and the main bearing housing  1038 . The second end plate  1248  may include a biasing passage  1258  that provides fluid communication between an intermediate-pressure compression pocket and the biasing chamber  1118 . 
     The second end plate  1248  may include a discharge passage  1260 . The discharge passage  1260  extends through the second end plate  1248  and provides fluid communication between a radially innermost one of the fluid pockets and the discharge-gas-outlet fitting  1035  (via the passage  1056  in the first bearing support member  1048 ). A discharge valve (e.g., a reed valve or other check valve) may be disposed within or adjacent the discharge passage  1260  or at the proximal end of the first bearing support member  1048 . The discharge valve allows working fluid to be discharged from the compression mechanism  1018  through the discharge passage  1260  and into the first bearing support member  1048  and prevents working fluid in the first bearing support member  1048  from flowing back into to the compression mechanism  1018 . A main portion of the discharge gas flowing out of the discharge passage  1260  may flow through the passage  1056  of the first bearing support member  1048 , into the discharge-pressure chamber  1034  and out of the compressor  1000  through the discharge-gas-outlet fitting  1035 . 
     A portion of the discharge gas flowing out of the discharge passage  1260  may flow through the second bearing  1080 , between the first bearing support member  1048  and the second bearing support member  1052 , through the first bearing  1076 , and into the internal space  1033 . The discharge gas in the internal space  1033  may circulate through the motor assembly  1016  to cool the motor assembly  1016 . 
     The motor assembly  1016  may be disposed within the internal space  1033  (at discharge pressure) and may include a motor stator  1264  and a rotor  1268 . The motor stator  1264  may be attached to the shell  1022  (e.g., via press fit, staking, epoxy, glue, adhesive, and/or welding). The rotor  1268  may be attached to the second bearing support member  1052  (e.g., via press fit, staking, and/or welding). The second bearing support member  1052  may be driven by the rotor  1268  and may be supported by bearings  1076  and  1136  for rotation relative to the shell assembly  1012 . The bearing  1076  may be fixed to the first bearing support member  1048  and the second bearing support member  1052 . The third bearing  1136  may be fixed to the central hub  1128  and the driveshaft  1164 . In some configurations, the motor assembly  1016  is a variable-speed motor. In other configurations, the motor assembly  1016  could be a multi-speed motor or a fixed-speed motor. 
     Attaching the motor stator  1264  to the shell  1022  and the rotor  1268  to the second bearing support member  1052  positions the motor assembly  1016  about the second bearing support member  1052 , instead of about the driveshaft  1164 . Placement of the motor assembly  1016  about the second bearing support member  1052  reduces the compressor  1000  footprint. The shaft section  1172  of the driveshaft  1164  may be reduced in length, reducing an overall length of the compressor  1000 . A reduction in the footprint of the compressor  1000  reduces the thermal communication of the suction gas with other parts of the compressor  1000 , reducing pre-heat. 
     Following the arrows in  FIG.  13   , during use, a working fluid enters the compressor  1000  through the suction gas inlet fitting  1032  in the first end cap  1024  of the compressor  1000  (Arrow A). The working fluid may include both a refrigerant and an oil (for example, an oil mist). Since the compressor  1000  is a sumpless compressor, the oil for heat transfer and lubrication of moving parts travels with the working fluid through the compressor  1000 . For example, the refrigerant may include, but is not limited to, one or more of R410a, R290, R744, R32 R454b, R134a, 404A, 407A/C/F, 507, and R717. For example, the oil may include, but is not limited to, one or more of Mineral Oil, Alkyl Benzene, Polyol Ester, and Polyalkylene glycol, as a few examples. 
     The working fluid, at suction pressure, enters the suction-pressure chamber  1134  from the suction gas inlet fitting  1032 . The suction-pressure working fluid is pulled into the suction passage  1180  within the driveshaft  1164  (Arrow B). The working fluid moves through the driveshaft  1164  towards the compression mechanism  1018 . The working fluid travels through the output  1192  of the suction passage  1180  and into the radially extending passage  1240  defined by the space between the hub  1176  and the first end plate  1228  (Arrow C). 
     The working fluid is received in the axially extending passage  1236  from the radially extending passage  1240  (Arrow D). The axially extending passage  1236  provides an entrance into the suction inlet  1244  in the compression mechanism  1018 . The working fluid is compressed within the pockets defined by the first spiral wrap  1232  of the first, driving scroll  1168  and the second spiral wrap  1256  of the second, driven scroll  1120  (Arrow E). 
     The compressed working fluid is discharged through the discharge passage  1260  in the second end plate  1248  of the second, driven scroll  1120  (Arrow F). The compressed working fluid is at a high-pressure (i.e., compression pressure, or a pressure higher than the suction pressure) and flows through the discharge passage  1056  in the first bearing support member  1048 . A portion of the working fluid exits the discharge passage  1056  through the first series of apertures  1060  at the proximal end of the discharge passage  1056 . 
     The portion of working fluid may travel through the second bearing  1080 , between the first bearing support member  1048  and the second bearing support member  1052 , and the first bearing  1076  and into the interior space  1033  (Arrow G). The portion of the working fluid in the internal space  1033  may circulate through the motor assembly  1016  to transfer heat away from the motor assembly  1016  and cool the rotor  1268  and stator  1264  (Arrow H). 
     The compressed working fluid in the discharge passage  1056  enters the discharge-pressure chamber  1034  (Arrow J). The compressed fluid circulates within the discharge-pressure chamber  1034  (Arrow K). Apertures  1031  in the partition  1025  provide fluid communication between the discharge-pressure chamber  1034  and the interior space  1033  (Arrow L). Compressed working fluid may flow from the discharge-pressure chamber  1034  to circulate through the motor assembly  1016 , as previously described. Compressed working fluid from the motor assembly  1016  in the interior space  1033  may flow into the discharge-pressure chamber  1034  to exit the compressor  1000  through the discharge gas outlet fitting  1035  (Arrow M). 
     In an alternative example, the compressor  1000  may include an impeller (not shown), similar to impeller  204  in compressor  200 , disposed between the flange  1216  and the first end plate  1228  of the first scroll member  1168 , which defines the suction plenum. The impeller may define a passage, similar to the radially extending passage  1240 , which extends from the output  1192  to the axially extending passage  1236 , to streamline the gas flow from the output  1192  to the axially extending passage  1236 . The streamlined flow may reduce pressure drops between the output  1192  and the compression mechanism  1018 . Additionally, the impeller provides pre-compression of the working fluid, where the working fluid is dynamically compressed prior to the compression mechanism  1018  utilizing a centrifugal effect. The streamlined flow may, in certain conditions, provide a supercharging effect. 
     As described with respect to impeller  204 , the impeller may be formed of a thermally insulated material. For example, the thermally insulated material may include, but is not limited to, ceramics, silicone, thermal insulating sprays, plastics, ceramics, or graphite. The thermally insulating impeller may reduce the heat transfer into the refrigerant flowing through the passage in the impeller toward the axially extending passage  1236  and compression mechanism  1018 . Reduction in the heat transfer may improve the volumetric efficiency of the refrigerant. 
     The impeller may be formed integrally with the first end plate  1228  of the first scroll member  1168  to create a single, monolithic piece. Accordingly, the position of the impeller relative to the first scroll member  1168  may be fixed. Further, forming the impeller with the first end plate  1228  creates easier and more reliable assembly of the compressor  1000 . Alternatively, the impeller may fit within a recessed portion in the first end plate  1228  of the first scroll member  1168 . The recessed portion may locate and fix the position of the impeller relative to the flange  1216  and the first scroll member  1168 . Alternatively, the impeller may be formed integrally with the hub  1176  or with the driveshaft  1164 . 
     During compressor  1000  operation, the working fluid, at suction pressure, moves through the driveshaft  1164  towards the compression mechanism  1018 . The working fluid travels through an output  1192  of the suction passage  1180  and into the passage defined by the impeller. The working fluid is received in the axially extending passage  1236  from the passage defined by the impeller. The working fluid is compressed within the pockets defined by the first spiral wrap  1232  of the first driving scroll  1168  and the second spiral wrap  1256  of the second, driven scroll  1120 . 
     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.