Abstract:
Disclosed is a compressor ( 12 ) for a refrigeration system ( 10 ) including a housing ( 30 ) and at least one compressor impeller ( 24, 26 ) located in the housing ( 30 ) capable of compressing a refrigerant flow ( 14 ) through the compressor ( 12 ). At least one refrigerant pathway ( 44, 62 ) is located inboard of an outer surface ( 48 ) of the housing ( 30 ) and extends from a first compressor impeller ( 24 ). Further disclosed is a refrigeration system ( 10 ) including a compressor ( 12 ) having at least one refrigerant pathway ( 44, 62 ) located inboard of an outer surface ( 48 ) of the housing ( 36 ) and extending from a first compressor impeller ( 24 ) of at least one compressor impeller ( 24, 26 ). Further disclosed is a method of flowing refrigerant through a compressor ( 12 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The subject matter disclosed herein relates to compressors. More specifically, the subject disclosure relates to fluid flow in a compressor. 
         [0002]    Compressors are utilized in many different applications, for example, in vapor cycle refrigeration systems. In a typical vapor cycle refrigeration system, a circulating refrigerant flows through four components: a compressor, a condenser, an expansion valve and an evaporator. The refrigerant, in a vapor state, is compressed and heated in the compressor, then is condensed into a liquid in the condenser by a heat sink. The liquid refrigerant then undergoes a rapid reduction in pressure when routed through the expansion valve. The rapid expansion causes an evaporation of at least a portion of the refrigerant resulting in a lowering of the temperature of the refrigerant. The liquid portion of the refrigerant is then evaporated in the evaporator and heat is absorbed from a fluid, typically air for example, flowing thru the evaporator. Compressor power is typically provided by an electric motor. 
         [0003]    The compressor portion, powered by an electrical motor, typically includes one or more compressor impellers rotatably located about a rotor shaft in a compressor housing assembly. The refrigerant passes through the impellers in succession, increasing the pressure and the temperature of the refrigerant. In many compressors, impellers are located at opposing ends of the compressor to improve rotor dynamics conditions. To convey the refrigerant between the impellers, one or more conduits are provided external to the housing assembly and connected at one or more ports. The refrigerant passes through a first impeller and exits the housing through the one or more ports into a first end of the one or more conduits and reenters the housing via ports near a second impeller and passes through the second impeller. In some systems, during the flow along the one or more conduits, the refrigerant is passed through a heat exchanger to remove heat generated from the compression via the first impeller. Additionally, a motor stator portion is located between the first and second impeller and is subjected to the heat due to the inefficiency in converting electric power to mechanical power. To cool the stator, cooling jackets are often added around the exterior of the stator portion. 
         [0004]    The porting and connections to external conduits introduce additional components to the system and add weight. Further, the connections introduce a potential source of leakage which negatively impacts the performance and efficiency of the compressor and the refrigeration system. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0005]    According to one aspect of the invention, a compressor for a refrigeration system includes a housing and at least two compressor impellers capable of compressing a refrigerant flow through the compressor. At least one refrigerant pathway is located inboard of an outer surface of the housing and extends from a first impeller of at least one impeller. 
         [0006]    According to another aspect of the invention, a refrigeration system includes a condenser, an expansion valve in fluid communication with the condenser and an evaporator in fluid communication with the expansion valve. The system further includes a compressor in fluid communication with the condenser and the evaporator. The compressor includes a housing and at least one compressor impeller located in the housing capable of compressing a refrigerant flow through the compressor. At least one refrigerant pathway is located inboard of an outer surface of the housing and extends from a first impeller of the at least one impeller. 
         [0007]    According to yet another aspect of the invention, a method of flowing refrigerant through a compressor includes urging a refrigerant flow past a first compressor impeller of at one compressor impeller located in a compressor housing and urging the refrigerant flow through at least one refrigerant pathway extending from the first impeller. The at least one refrigerant pathway is located inboard of an outer surface of the compressor housing. 
         [0008]    These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0010]      FIG. 1  is a schematic view of an embodiment of a vapor cycle refrigeration system; 
           [0011]      FIG. 2  is a cross-sectional view of an embodiment of a compressor; 
           [0012]      FIG. 3  is a perspective view of an embodiment of a stator section for a compressor; and 
           [0013]      FIG. 4  is a cross-sectional view of another embodiment of a compressor. 
       
    
    
       [0014]    The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0015]    Shown in  FIG. 1  is schematic view of an embodiment of a vapor cycle refrigeration system  10 . The system  10  includes a compressor  12  in which a circulating refrigerant flow  14  in a vapor state is compressed and heated. The refrigerant flow  14  is urged to a condenser  16  where the refrigerant flow  14  is condensed into a liquid state. The refrigerant flow  14  is rapidly depressurized in an expansion valve  18  which reduces the temperature of the refrigerant flow  14 . The cooled refrigerant flow  14  is then routed to an evaporator  20  where it is evaporated and absorbs heat from a fluid flowing across the evaporator  20  by, for example, air as propelled by a fan  22 . 
         [0016]      FIG. 2  illustrates an embodiment of the compressor  12 . The compressor  12  includes two compressor impellers, a first impeller  24  and a second impeller  26  axially secured to a shaft  28 . In some embodiments, the first compressor impeller  24  and/or the second compressor impeller  26  are centrifugal rotors. In the embodiment of  FIG. 2 , the first compressor impeller  24  and the second compressor impeller  26  are disposed at substantially opposing ends of the shaft  28  for improved rotor dynamic characteristics. It is to be appreciated that other configurations, for example, ones where the first impeller  24  and second impeller  26  are disposed substantially adjacent on the shaft  28 , are contemplated within the scope of the present disclosure. Further, while the quantity of compressor impellers illustrated in  FIG. 2  is two, it is merely used as an example, and other quantities of compressor impellers, for example, 1, 3 or 4 or more compressor impellers, may be utilized. The compressor impellers  24  and  26  are disposed in a housing set  30 , which in some embodiments comprises a first housing portion  32  and a second housing portion  34 . In some embodiments, the first compressor impeller  24  is disposed in the first housing portion  32  and the second compressor impeller  26  is disposed in the second housing portion  34 . Between the first compressor impeller  24  and the second compressor impeller  26 , at least one motor stator section  36  is disposed in the housing  30 . 
         [0017]    The first housing portion  32  includes at least one input port  38  for input of the refrigerant flow  14  from the evaporator  20 . The refrigerant flow  14  is urged to the first compressor impeller  24  by rotation of the first compressor impeller  24 . The first compressor impeller  24  accelerates the refrigerant flow  14  through a first rotor channel  40  between the first compressor impeller  24  and a first housing member  42 . The first rotor channel  40  gets progressively narrower along its length to increase the pressure of the refrigerant flow  14 . The refrigerant flow  14  in some embodiments is urged substantially radially outwardly toward at least one first housing passage  44  disposed between an inner surface  46  and an outer surface  48  of the first housing portion  32 . The at least one first housing passage  44  extends through the first housing portion  32  from the first rotor channel  40  to the motor stator section  36 . The refrigerant flow  14  is urged therethrough toward the motor stator section  36 . 
         [0018]    Referring now to  FIG. 3 , the motor stator section  36  includes a plurality of motor stator members  50 , extending substantially from a first motor stator end  52  to a second motor stator end  54  of the motor stator section  36 . At least one stator slot  56  is disposed between adjacent motor stator members  50  of the plurality of motor stator members  50 . A plurality of stator passages  58  are formed between the at least one stator slot  56 , at an outer surface  60  of the motor stator section  36  and the inner surface  46  of the housing  30 . The plurality of stator passages  58  are disposed and configured to be in connected to the at least one first housing passage  44  so that the refrigerant flow  14  is urged from the at least one first housing passage  44  through the plurality of stator passages  58  from the first motor stator end  52  to the second motor stator end  54  of the motor stator section  36  toward the second housing section  34 . Flowing the refrigerant flow  14  through the plurality of stator passages  58  provides cooling to the motor stator section  36  so that, in some embodiments, additional cooling of the motor stator section  36  via, for example, cooling jackets, is not needed. 
         [0019]    Referring again to  FIG. 2 , the second housing section  34  includes at least one second housing passage  62 . The at least one second housing passage  62  is disposed internal to the second housing section  34  between the inner surface  46  and the outer surface  48  of the second housing section  34 , and is configured such that the refrigerant flow  14  is urged from the plurality of stator passages  58  into the at least one second housing passage  62 . The refrigerant flow  14  flows through the at least one second housing passage  62  toward the second compressor impeller  26 . The second compressor impeller  26  accelerates the refrigerant flow  14  through a second rotor channel  64  between the second compressor impeller  26  and a second housing member  66 . The second rotor channel  64  gets progressively narrower along its length to increase the pressure of the refrigerant flow  14 . In some embodiments, after being urged past the second compressor impeller  26 , the refrigerant flow  14  exits the compressor  12  and flows toward the condenser  16 . It is to be appreciated, however, that in other embodiments in which the compressor  12  comprises additional compressor impellers, the flow of refrigerant  14  continues to subsequent impellers in the compressor  12  in a substantially similar manner to that described above. As shown in  FIG. 2 , in some embodiments the second housing passage  62  carries the refrigerant flow  14  to be urged past the second compressor impeller  26  at a first side  68  of the second compressor impeller  26  disposed closest to the first compressor impeller  24 . In other embodiments as, for example, shown in  FIG. 4 , the second compressor impeller  26  is disposed such that the first side  68  is disposed farthest from the first compressor impeller  24 . In this embodiment, the second housing passage  62  is configured and disposed such that the refrigerant flow  14  flows past the second compressor impeller  26  beginning at the first side  68 , located farthest from the first compressor impeller  24 . 
         [0020]    Flowing the refrigerant flow  14  internally through the compressor  12  from compressor impeller to compressor impeller, as opposed to externally, eliminates external hardware and connectors which provide opportunities for leakage of the refrigerant flow  14  from the compressor  12 . Further, elimination of parts reduces weight of the compressor  12 . A direct means of cooling the motor stator section  36  is provided, and heat from the motor stator section  36  eliminates liquid-state refrigerant from the refrigerant flow  14 , so that the entire flow through the compressor  12  is in a vapor state. The entirely vapor state improves operational efficiency of any subsequent compressor rotors and of fluid film bearings which are utilized in some embodiments to support the rotating elements. 
         [0021]    While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.