Abstract:
A compressor assembly including a housing having an oil sump containing a liquid lubricant, a compressor mechanism disposed within the housing, a vertical, rotatable shaft associated with the compressor mechanism and provided with a conduit having a downwardly directed open end extending beneath the surface level of the lubricant and through which oil is conveyed to the compressor mechanism, whereby the lubricant is drawn into the conduit open end, and a guard in surrounding relationship with, and having an aperture disposed beneath and proximate to, the conduit open end, the guard fixed relative to the housing, the sump in fluid communication with the conduit through the aperture.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to lubrication systems for hermetic compressors and in particular vertically oriented hermetic compressors having a pick-up tube or shaft end which extends into the oil contained in a sump. 
     Hermetic compressors having hollow shafts or pick-up tubes which extend into the oil contained in a sump are used for drawing lubricant from the sump and providing it to moving parts of the compressor assembly. Often these tubes or shafts are provided with a paddle for pumping the oil through the shaft or tube. A problem experienced with pick-up tubes or shafts is that on their rotation they tend to create vortices around the end of the shaft or tube which extends into the oil. These vortices hinder the performance of oil delivery into the tube or shaft. A way of preventing the formation of these vortices is desirable. 
     SUMMARY OF THE INVENTION 
     The present invention provides an oil inlet guard disposed about the end of a rotating oil pickup tube or shaft provided with an oil passage opening. The guard is fixed such that it does not rotate and is provided with a central oil aperture through which oil flows from the sump into the rotating shaft or pick-up tube. The guard smooths the oil which flows into the pickup tube or shaft, eliminating flow-disrupting vortices and increasing the oil pick-up performance of the shaft or tube. 
     The present invention provides a compressor assembly including a housing having an oil sump in which is contained a liquid lubricant, a compressor mechanism disposed within the housing, a vertical, rotatable shaft associated with the compressor mechanism and provided with a conduit having an downwardly directed open end which extends beneath the surface level of the lubricant in the sump and through which oil is conveyed to the compressor mechanism, and a guard in surrounding relationship with the conduit open end and having an aperture disposed beneath and proximal to it, the guard fixed relative to the housing, the sump in fluid communication with the conduit through the guard aperture. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of the embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a sectional side view of a hermetic compressor according to a first embodiment of the present invention; 
     FIG. 2 is an enlarged fragmentary sectional side view of a portion of the compressor shown in FIG. 1, showing the pick-up tube and guard in greater detail; 
     FIG. 3 is a fragmentary sectional side view of a portion of a compressor according to a second embodiment of the present invention, showing the pick-up tube and guard; 
     FIG. 4 is a fragmentary sectional perspective view of the compressor portion shown in FIG. 2, also showing an alternative vent configuration; and 
     FIG. 5 is a fragmentary sectional perspective view of the compressor portion shown in FIG. 3, also showing an alternative vent configuration. 
     Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments 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. The exemplification set out herein illustrates one embodiment of the invention, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The embodiment disclosed below is not intended to be exhaustive or limit the invention to the precise form disclosed in the following detailed description. 
     Referring to FIG. 1, there is shown a first embodiment of a compressor according to the present invention. Vertically-oriented compressor assembly  20  is of the rotary type, although it is to be understood that the present invention is adaptable to other types of vertical compressors such as, for example, scroll compressors, rotary vane compressors and reciprocating piston compressors. Compressor assembly  20  comprises outer shell  22  and has, disposed within shell  22 , motor assembly  24  having stator  26  and rotor  28 . Rotor  28  is provided with shaft  30  having axial bore  32  extending therethrough. Shaft  30  is jounalled in main bearing  34  which comprises in part compressor mechanism  36 . 
     Compressor mechanism  36  is of the rotary type having cylinder block  38  disposed between axial surface  40  of bearing  34  and axial surface  42  of outboard bearing  44 . Cylinder block  38  is provided with cylindrical cavity  46  in which is disposed eccentric  48  attached to or integral with shaft  30 . Disposed about and rotatable relative to eccentric  48  is cylindrical piston  50  which moves about cavity  46  in an epicyclic fashion. A vane (not shown) is biased by a spring (not shown) against the outer surface of piston  50 , the vane reciprocating in a slot (not shown) provided therefor in cylinder block  38 . Discharge and suction ports (not shown) are disposed on opposite sides of the vane and allow refrigerant to enter and exit a compression chamber of compressor mechanism  36  in the known way. Refrigerant enters compressor mechanism  36  through via a suction tube (not shown) and exits compressor assembly  20  through discharge tube  52 , compressor assembly  20  being of the type in which the entire interior of shell  22  is at discharge pressure. 
     Disposed in the bottommost portion of shell  22  is lubricant sump  54  containing a quantity of oil having surface level  56 . As best seen in FIG. 2, shaft  30  has portion  58  radially supported in journal  60  of outboard bearing  44  and provided with pick-up tube  62  which is interference-fitted into a pump receiving portion  64  of shaft bore  32 . Within bore portion  64  is disposed helical paddle  66  which serves as a pump for helping to convey lubricant from sump  54  through shaft bore  32 . Paddle  66  may be retained in bore portion  64  by means of clip  65 . Pick-up tube  62  extends below surface level  56  of the lubricant in sump  54  and its tip  68  is provided with axial opening  69  (FIG. 2) through which oil is received into shaft bore  32 . 
     Alternatively, as shown in the second embodiment of FIG. 3, shaft portion  58 ′ itself extends below oil surface level  56 , with shaft  30 ′ not provided with a pick-up tube such as pick-up tube  62 . As seen in FIG. 3, paddle  66  is provided in shaft bore portion  64 ′, and may be retained therein by means of clip  65  or, as shown, by snap ring  67 . Further, shaft  30  or  30 ′ may not be provided with paddle  66  at all, instead relying on alternative pump means (not shown) for helping to convey lubricant from sump  54  through shaft bore  32 . 
     Affixed to the bottommost end of outboard bearing  44  is guard  70  which encloses oil pick up tube tip  68  and, as shown, may be somewhat hemispherically or domed shaped. Guard  70  is provided with aperture  72  which is downwardly directed and in close proximity with tip  68  of pick-up tube  62 . The inside surface of guard  70  near its aperture  72  is contoured such that it surrounds the open end of tip  68 . The vertical clearance between the bottommost portion of tip  68 , in which oil inlet aperture  69  is provided, and the inside surface of guard  70  therebeneath is preferably approximately 0.020 to 0.030 inch, indicated as distance A in FIG.  2 . Guard  70  is provided with cylindrical portion  74  which is interference-fitted into counterbore  76  provided in outboard bearing  44 . Provided in guard  70  near cylindrical portion  74  and below counterbore  76  is at least one vent  78  which allows air and oil to escape the interior of guard  70  during oil filling. As shown in FIG. 2, vent  78  may be formed by providing hole  80  in the surface of guard  70  or, as shown in FIG. 4, vent  78  may be formed by providing axially elongate notch  82  in cylindrical portion  74  of guard  70 . 
     Similarly, as shown in FIG. 3, the second embodiment of the present invention has, affixed to the bottommost end of outboard bearing  44 ′, guard  70 ′ which encloses tip  73  of shaft  30 ′ and may also be somewhat hemispherically or domed shaped and provided with downwardly directed aperture  72 ′. The inside surface of guard  70 ′ near its aperture  72 ′ is contoured such that it surrounds shaft tip  73 . The vertical clearance between tip  73  the inside surface of guard  70 ′ therebeneath is preferably approximately 0.020 to 0.030 inch, indicated as distance A in FIG.  3 . Aperture  72 ′ is in close proximity to tip  73  of shaft  30 , which may be contoured to approximate the inner surface configuration of guard  70 ′. The clearance between shaft tip  73  and the inside, adjacent surface of guard  70 ′ is likewise preferably approximately 0.020 to 0.030 inch. Guard  70 ′ is provided with cylindrical portion  74 ′ which is interference-fitted to annular shoulder  75  provided in outboard bearing  44 ′. To allow air and oil to escape the interior of guard  70 ′ during oil filling, at least one vent  78 ′ is provided in guard  70 ′ near cylindrical portion  74 ′ and below shoulder  75 . As shown in FIG. 3, vent  78 ′ may be formed by providing hole  80 ′ in the surface of guard  70 ′ or, as shown in FIG. 5, vent  78 ′ may be formed by providing axially elongate notch  82 ′ in cylindrical portion  74 ′ of guard  70 ′. 
     Guard  70 ,  70 ′ may be made of plastic or stamped sheet metal. As indicated above, in the shown embodiments guards  70 ,  70 ′ are interference-fitted to bearings  44 ,  44 ′, but may alternatively be adhered, welded or brazed thereto. Apertures  72 ,  72 ′ (FIGS. 2,  3 ) axial pickup tube opening  69  (FIG. 2) and/or shaft bore portion diameter  64 ′ (FIG. 3) are appropriately sized to accommodate the compressor size and type, and the amount of oil required for proper lubrication. 
     Referring to the first embodiment of FIGS. 1,  2  and  4 , in operation, as shaft  30  and pick-up tube  62  rotate within fixed outboard bearing  44  and guard  70  affixed thereto, oil from sump  54  enters guard aperture  72  and flows immediately into pick-up tube guard opening  69 . The oil outside of guard  70  is generally still, and does not have vortices which may disrupt the flow of lubricant through guard opening  72 , and thus into pick-up tube opening  69 . It is expected that vortices are created adjacent the outer surfaces of pick-up tube  62  inside of guard  70 , these vortices, however, do not appreciably adversely affect the flow of oil from sump  54  through openings  72 ,  69  into shaft bore  32 . As can be readily visualized with reference to FIGS. 3 and 5, the second embodiment of the present invention operates in the same way to prevent the formation of vortices within the oil sump which disrupt the flow of lubricant into the shaft bore. 
     While this invention has been described as having exemplary designs, the present invention may be further modified within the spirit and scope of this disclosure. Therefore, this application is intended to cover any variations, uses, or adaptations of the invention using its general principles. For example, aspects of the present invention may be applied to compressors other than rotary compressors, or may be adapted to compressors having the compressor mechanism located in the upper portion of the compressor shell, the depending end of the shaft immersed in the sump, its conduit opening within the inventive guard as described above. 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.