Abstract:
A hermetic scroll-type compressor including a housing having a motor mounted therein. A compression mechanism is also mounted in the housing and is operatively coupled to the motor. The compression mechanism is secured to a crankcase having a shield surface integrally formed thereon. A suction tube is provided having an outlet end mounted in the housing. At least a portion of the shield surface is substantially aligned with the outlet end such that an oil and refrigerant gas mixture entering the housing via the suction tube impinges upon the shield surface, whereby oil separates from the mixture.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to scroll compressors, and more particularly to an oil shield for directing and separating oil from suction pressure fluid entering the compressor.  
           [0002]    In general, a scroll compressor includes a compressor housing having a suction gas tube with an outlet end mounted in the housing. The suction pressure fluid entering the compressor is an oil and refrigerant mixture which passes through the suction gas tube outlet end into the compressor housing. The suction gas tube is commonly spaced from the suction inlet of the compression mechanism to prevent the substantial amount of oil entrained in the incoming refrigerant from being drawn into the compression mechanism.  
           [0003]    In some compressors, the oil and refrigerant gas mixture disperses throughout the housing if it is not directed toward a particular portion of the compressor upon entering the compressor housing. The oil and refrigerant mixture then comes into contact with several of the compressor components including the crankcase, counterweight, and motor.  
           [0004]    A problem with allowing the oil and refrigerant mixture to disperse once it enters the compressor housing is that the fluid flowing over the motor may be insufficient to cool the motor. Further, a portion of the oil entrained in the refrigerant needs to be separated therefrom to prevent substantial amounts of oil from entering the compression mechanism with the suction pressure refrigerant gas. The entrained oil clings to the compressor components as it comes into contact therewith, and eventually drips into the oil sump formed in the bottom of the housing. However, rotation of the crankshaft, counterweight, and motor causes the oil collected thereon to be thrown therefrom toward the inside of the compressor housing. This further delays the collection of oil as it takes time for the oil to collect and drip into the oil sump.  
           [0005]    Conventionally, a baffle or oil shield may be mounted to the interior of the compressor housing, being located over and extending substantially above the suction gas tube. One example of a baffle or oil shield is described in U.S. Pat. No. 5,055,010 to Logan. The shield is attached to the inner surface of the housing by projection welding, for example. As the refrigerant and oil mixture enters the compressor housing, it comes into contact with the oil shield. The oil in the mixture clings to the shield and collects thereon. The collection of oil then drips down into the oil sump in the compressor housing. A substantial portion of the refrigerant, now substantially void of entrained oil, is directed toward the suction inlet of the compression mechanism. A smaller portion of the refrigerant is directed downwardly over the motor to cool the motor.  
           [0006]    A problem with the previously used oil shields is that the shield is a separate compressor component, thus increasing the cost of the compressor. Further, the cost of assembly increases as the oil shield has to be secured to the inner surface of the housing.  
           [0007]    It is desired to provide a cost effective oil shield for directing incoming suction pressure fluid and separating oil from the fluid.  
         SUMMARY OF THE INVENTION  
         [0008]    The present invention relates to a hermetic scroll compressor having an oil shield surface integrally formed with the compressor crankcase. The oil shield surface is positioned above the outlet of the suction gas tube mounted in, and opening into, the compressor housing. A mixture of oil and suction pressure refrigerant gas enters the compressor housing through the suction gas tube and contacts the oil shield surface. A substantial portion of the oil in the mixture clings to the oil shield surface and is separated from the gas. The oil collecting on the oil shield surface drips down to an oil sump formed in the lower portion of the compressor housing. A portion of the refrigerant, being substantially free of oil, is directed by the oil shield surface into the inlet of the compression mechanism and over the motor to cool the motor.  
           [0009]    The present invention provides a hermetic compressor including a housing having a motor and a compression mechanism mounted therein. The motor and compression mechanism are operatively coupled. The compression mechanism is secured to a crankcase having a shield surface integrally formed thereon. A suction tube is provided having an outlet end mounted in the housing with at least a portion of the shield surface being substantially aligned with the outlet end. An oil and refrigerant gas mixture enters the housing via the suction tube and impinges upon the shield surface, whereby oil separates from the mixture.  
           [0010]    The present invention also provides a hermetic compressor including a housing having a motor and a compression mechanism mounted therein. The motor and the compression mechanism are operatively coupled. A crankcase is mounted in the housing and is located between the compression mechanism and the motor. A shield surface is integrally formed on the crankcase, wherein an oil and refrigerant gas mixture being introduced into the housing impinges upon the shield surface and the oil is thereby separated from the mixture.  
           [0011]    The present invention provides a method of separating an oil and refrigerant gas mixture entering a hermetic compressor having a housing with a motor mounted therein, a crankcase mounted atop the motor, and a compression mechanism operatively associated with the motor. The method includes drawing refrigerant gas entrained with oil into the compressor through a suction gas tube mounted in the housing; and directing the refrigerant gas entrained with oil into contact with a shield surface integrally formed with the crankcase, the oil clinging to the shield surface and the refrigerant being directed over the motor mounted in the compressor housing and into the compression mechanism.  
           [0012]    One advantage of the present invention is that the oil shield surface is integrally molded with the crankcase, thus reducing the number of compressor components.  
           [0013]    A further advantage of the present invention is that the assembly step of welding the shield to the inner surface of the compressor housing is eliminated, thus reducing the cost of assembly. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    The above-mentioned and other features and objects of this invention, and the manner of attaining them, will become more apparent when the invention itself will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:  
         [0015]    [0015]FIG. 1 is a sectional view of a compressor assembly in accordance with the present invention;  
         [0016]    [0016]FIG. 2 is a perspective view of a crankcase of the compressor assembly shown in FIG. 1; and  
         [0017]    [0017]FIG. 3 is a top plan view of a crankcase of FIG. 2 shown mounted in the compressor housing. 
     
    
       [0018]    Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent an embodiment of the present invention, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the present invention.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0019]    Referring to FIG. 1, hermetic scroll compressor  10  includes housing  12  formed from main shell  14 , top end cap  16 , bottom end cap  17 , and base plate  18 . End cap  16  is welded at  15  to the upper end of main shell  14  and separator plate  21 . Base plate  18  is provided with annular support  19  for supporting compressor  10  in a substantially vertical orientation. Base plate  18  is welded at  15  to the lower end of bottom end cap  17  which is in turn welded to main shell  14 .  
         [0020]    Separator plate  21  divides housing  12  into discharge chamber  90  and suction pressure chamber  94  in which motor  20  is mounted to main housing shell  14  by being, e.g., interference or shrink fitted therein. Motor  20  includes stator  24  located in surrounding relationship of rotor  26 . Rotor  26  is provided with central aperture  28  in which drive shaft  30  is interference fitted for rotation with rotor  26 . The lower end of drive shaft  30  is rotatably supported in outboard bearing  36  secured to the lower end of main shell  14  by interference fit. The upper end of drive shaft  30  is rotatably supported in aperture  34  formed in crankcase  32  which is fixedly mounted onto upper surface  23  of stator  24 . The upper end of drive shaft  30  engages compression mechanism  22  which is mounted atop crankcase  32  by screws  40 . Drive shaft  30  rotates with rotor  26  to drive compression mechanism  22  which in turn compresses refrigerant fluid located in the compression mechanism.  
         [0021]    Compressor  10  is a scroll-type compressor with compression mechanism  22  including fixed scroll member  42  and orbiting scroll member  44 . Fixed scroll member  42  and orbiting scroll member  44  includes flat plates  46 ,  50 , respectively, having scroll wraps  48 ,  52  extending therefrom. When fixed member  42  and orbiting member  44  are assembled, scroll wraps  48  and  52  intermesh, creating a plurality of compression chambers  54  therebetween. Orbiting scroll member  44  is positioned between crankcase  32  and fixed scroll member  42  such that back surface  56  of orbiting scroll member plate  50  is in contact with thrust surface  58  of crankcase  32 . Annular hub  60  extends from back surface  56  of plate  50  having cavity  62  formed therein in which bearing  64  and roller  66  are located. Hub  60 , bearing  64 , and roller  66  are received in cavity  65  formed in crankcase  32 . Bearing  64  surrounds roller  66  which is provided with aperture  67  to receive eccentric  68  integrally formed at the end of drive shaft  30  to drivingly couple compression mechanism  22  and drive shaft  30 .  
         [0022]    The operation of compressor  10  includes motor  20  being electrically energized in a conventional manner, thus inducing rotation of rotor  26  and in turn drive shaft  30 . Suction pressure refrigerant gas is drawn into suction pressure chamber  94  defined by separator plate  21  and compressor housing  12  to supply compression mechanism  22  as will be discussed further below. As drive shaft  30  rotates, orbiting scroll member  44  orbits relative to fixed scroll member  42 . The orbital movement of orbiting scroll member  44  causes compression chambers  54  to vary in size, thus compressing the suction pressure gas refrigerant to a higher, discharge pressure. The discharge pressure gas is exhausted from compression mechanism  22  through port  88  formed in flat plate  46  of fixed scroll member  42 . The discharge pressure gas enters discharge chamber  90  defined by end cap  16  and exits compressor  10  through discharge gas tube  92  to enter the remainder of a refrigeration system (not shown).  
         [0023]    Referring to FIGS. 2 and 3, crankcase  32  includes main body portion  69  in which aperture  34  and cavity  65  are formed. A plurality of legs  70  are circumferentially spaced about the periphery of main body portion  69  extending downwardly therefrom. Legs  70  are connected to main body portion  69  by webs  71  which radially extend from main body portion  69 . Upper portion  73  of legs  70  extends slightly above thrust surface  58  of main body portion  69  and has flat surfaces  72  with aperture  74  formed therein. When compressor  10  is assembled, fixed scroll member  42  of compression mechanism  22  is in contact with flat surfaces  72 . Screws  40  are then used to engage both fixed member  42  and apertures  74  of crankcase  32 , encasing orbiting scroll member  44  between the crankcase and fixed member, and securing compression mechanism  22  to crankcase  32 . Lower portion  75  of legs  70  extend downwardly past the lower end of main bearing portion  69  of crankcase  32  and are provided with flat surfaces  76  (FIG. 1) which are in contact with upper surface  23  of stator  24 . Legs  70  are secured to stator  24  using any suitable method. One such method may include using threaded fasteners that pass upwardly through the entire length of stator  24  and engage legs  70 . Legs  70  are elongated to space compression mechanism  22  above motor  20 .  
         [0024]    Referring to the Figures, integrally formed with crankcase  32 , between a pair of adjacent legs  70  is oil shield surface  78 . The upper edge of oil shield surface  78  is substantially flush with flat surfaces  72  of the adjacent legs  70  between which shield  78  is formed. Oil shield surface  78  extends downwardly a predetermined distance so as to be positioned over outlet end  82  of suction gas tube  80  (FIG. 3) mounted in compressor housing  12 . An oil and refrigerant mixture passes through outlet end  82  as it enters compressor  10  and comes into contact with surface  84  of oil shield surface  78 . When the mixture hits surface  84 , oil entrained in the refrigerant clings to oil shield surface  78 . The oil collects on surface  84  and eventually drips onto motor  20 . The oil flows downwardly around motor  20  to sump  86  (FIG. 1) formed in the lower end of housing  12 . A small portion of the suction pressure refrigerant, substantially free from oil, is directed downwardly over motor  20  to cool motor. The remainder of the suction pressure refrigerant gas is directed upwardly into compression chambers  54  in compression mechanism  22  where it is compressed to discharge pressure.  
         [0025]    While this invention has been described as having an exemplary design, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains.