Patent Publication Number: US-9835156-B2

Title: Sealing arrangement for semi-hermetic compressor

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to compressors and, more particularly, to sealing the casing end cover(s) to the body casing of a semi-hermetic compressor. 
     Semi-hermetic compressors are commonly used in many air conditioning and refrigeration applications to compress a refrigerant fluid for circulation through a refrigerant circuit wherein the compressor, a refrigerant heat rejection exchanger, an expansion device and a refrigerant heat absorption heat exchanger are arranged in serial refrigerant flow relationship. Semi-hermetic compressors include a casing main body housing a compression mechanism and a motor for driving the compression mechanism. A casing end cover(s) mounted to the casing main body by bolts closes the open end(s) of the casing main body. 
     For example, co-pending U.S. patent application publication number US 2011/0171044 A1, assigned to the common assignee to which this application is subject to assignment, discloses a semi-hermetic reciprocating compressor having a casing main body having a first open end and a second open end. A first end cover is mounted by bolts to the first open end of the casing main body and a second end cover is mounted by bolts to the second open end of the casing main body. To seal the respective interfaces between the casing main body and the casing end covers, a face seal gasket in disposed between each casing end cover and a flange on the end of the casing main body to which the casing end cover is mounted. To ensure that the face seal gasket forms a tight seal, a plurality of bolts disposed at spaced intervals around the flanges must be used to mount the casing end covers to the respective ends of the casing main body. In the reciprocating compressor illustrated in FIG. 1 of the aforementioned U.S. patent application publication number US 2011/0171044 A1, ten bolts are used to mount the casing end cover to the main bearing end of the casing main body and eighteen bolts are used to mount the casing end cover to the motor end of the casing main body. 
     SUMMARY OF THE INVENTION 
     A semi-hermetic compressor includes a casing main body having an end with an end opening, a casing end cover interfacing with the casing end over the end opening, and a sealing arrangement for sealing the interface between the casing main body and the casing end cover. A circumferential lip on the casing main body surrounds the end opening and defines a first radially facing circumferential surface. The end cover has a circumferential lip defining a second radially facing circumferential surface. The first circumferential surface and the second circumferential surface interface along an endless circumferential interface. A sealing arrangement is provided for sealing the interface. The sealing arrangement includes a first circumferentially extending groove formed in one of the first and second circumferential surfaces and a sealing member disposed within the first groove in sealing contact with the first groove and in sealing contact with the other one of the first and second circumferentially extending surfaces. The circumferential lip on the casing end cover may be circumscribed by the circumferential lip on the casing main body or the circumferential lip on the casing end cover may circumscribe the circumferential lip on the casing main body. 
     In an embodiment of the sealing arrangement, the first groove is formed in the second circumferential surface. In an embodiment of the sealing arrangement, first groove is formed in the first circumferential surface. In an embodiment of the sealing arrangement, a first circumferentially extending groove is formed in one of the first and second circumferentially extending surfaces, a second circumferentially extending groove is formed in the other of the first and second circumferential surfaces opposite the first groove, and the sealing member is disposed within a pocket formed by alignment of the first and second grooves when the first and second circumferentially extending surfaces are disposed in interfacing relationship. The sealing member is disposed in sealing contact with a base of the first groove and with a base of the second groove. In an embodiment, the first circumferential surface circumscribes the second circumferential surface. In an embodiment, the second circumferential surface circumscribes the first circumferential surface. 
     In an aspect, a sealing arrangement is provided for sealing an interface between a circumscribing surface and a circumscribed surface. The sealing arrangement includes a first circumferentially extending groove formed in one of the circumscribed and the circumscribing surfaces, and a sealing member disposed within the first circumferentially extending groove in sealing contact with a base of the first groove and in sealing contact with the other one of the circumscribed surface and the circumscribing surface. In an embodiment, the first circumferentially extending groove is formed in the circumscribing surface and the sealing member is in sealing contact with a face of the circumscribed surface. In an embodiment, the first circumferentially extending groove is formed in the circumscribed surface and the sealing member is in sealing contact with a face of the circumscribing surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a further understanding of the disclosure, reference will be made to the following detailed description which is to be read in connection with the accompanying drawing, wherein: 
         FIG. 1  is a side elevation view of an embodiment of an open drive semi-hermetic reciprocating compressor; 
         FIG. 2  is a side elevation view, mainly in section, of the compressor of  FIG. 1 ; 
         FIG. 3  is a side elevation view of an embodiment of a closed drive semi-hermetic reciprocating compressor; 
         FIG. 4  is a side elevation view, mainly in section, of the compressor of  FIG. 3 ; 
         FIG. 5  is a side elevation view of the region  5 - 5  of each of  FIGS. 2 and 4  showing an embodiment of a sealing arrangement as disclosed herein; 
         FIG. 6  is a side elevation view of the region  5 - 5  of each of  FIGS. 2 and 4  showing an alternate embodiment of a sealing arrangement as disclosed herein; 
         FIG. 7  is a side elevation view of the region  7 - 7  of each of  FIGS. 2 and 4  showing an embodiment of a sealing arrangement as disclosed herein; 
         FIG. 8  is a side elevation view showing another embodiment of a sealing arrangement as disclosed herein; 
         FIG. 9  is a side elevation view showing another embodiment of a sealing arrangement as disclosed herein in an embodiment of the compressor wherein the casing end cover circumscribes the open end of the compressor; 
         FIG. 10  is a side elevation view showing another embodiment of the sealing arrangement as disclosed herein in an embodiment of the compressor wherein the casing end cover circumscribes the open end of the compressor; and 
         FIG. 11  is a side elevation view showing another embodiment of the sealing arrangement as disclosed herein in an embodiment of the compressor wherein the casing end cover circumscribes the open end of the compressor. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     There is depicted in  FIGS. 1 and 2  an open drive embodiment of a semi-hermetic reciprocating compressor  10  embodying a sealing arrangement as disclosed herein. There is depicted in  FIGS. 3 and 4  a closed drive embodiment of a semi-hermetic reciprocating compressor  10  embodying a sealing arrangement as disclosed herein. In each embodiment, the reciprocating compressor  10  includes a casing main body  12 , a base  14 , a first casing end cover  16  and a second casing end cover  18 . The casing main body  12  extends generally along a longitudinal axis  20  from an open first end  22  that receives the first casing end cover  16  to an open second end  24  that receives the second casing end cover  18 . 
     The reciprocating compressor  10  includes a crankshaft  26  disposed for rotation about the axis  20 . A plurality of pistons  36  are connected by piston rods to the crankshaft  26  in a conventional manner for linear translation motion within respective cylinders  38  within the crankcase  32 . In operation, the crankshaft  26  is driven in rotation about the axis  20  which translates into reciprocating linear movement of the pistons  36  within their respective cylinders  38 . A gaseous fluid, such as for example refrigerant vapor, is drawn into the chamber  35  of a cylinder  38  during an intake stoke as the piston  36  disposed therein is moving away from the cylinder head. The gaseous fluid drawn into the cylinder chamber  35  is compressed during a compression stroke as the piston  36  moves toward the cylinder head, and the compressed gaseous fluid is discharged from the cylinder chamber  35  through an outlet  39  during a discharge stroke. 
     In the open-drive embodiment of the reciprocating compressor  10  as depicted in  FIG. 2 , the crankshaft  26  extends longitudinally from an end  27  disposed outside the casing main body  12  of the compressor  10 , through a central bore in the first casing end cover  16 , through a first end bearing  30 , thence through the crankcase  32  and into a second end bearing  33  supported by the second end cover  18 . In operation, the crankshaft  26  is driven in rotation by an external driver (not shown), such as for example a motor or an engine, connected to the end  27  of the crankshaft  26  outside the first casing end cover  16 . 
     In the closed drive embodiment of the reciprocating compressor  10  as depicted in  FIG. 4 , the crankshaft  26  is housed entirely within the compressor  10 . The crankshaft  26  extends longitudinally from a first end disposed within a drive motor  28  mounted about the crankshaft  26 , through a main bearing  34 , thence through the crankcase  32  and into an end bearing  33  supported by the second end cover  18 . In operation, the crankshaft  26  is driven in rotation by the motor  28 , which is powered by electric current supplied from an external source. 
     To prevent leakage of the higher pressure interior of the main casing  12 , it is necessary to seal the respective interfaces between the open ends  22 ,  24  of the casing main body  12  and the respective first and second casing end covers  16 ,  18 . The semi-hermetic reciprocating compressor  10  embodies an improved sealing arrangement as disclosed herein, generally designated  40 , at both ends of the casing main body  12  for sealing the interface between the first end cover  16  and the first open end  22  of the casing main body  12  and for sealing the interface between the second end cover  18  and the second open end  24  of the casing main body  12 . Rather than relying on a face gasket seal between the respective ends of the casing main body  12  and the respective first and second casing end covers  16 ,  18  as in conventional practice, the sealing arrangement  40  provides a more robust circumferential seal between the respective ends of the casing main body  12  and the respective first and second casing end covers  16 ,  18 . 
     Referring now to  FIGS. 5 and 6 , there are depicted embodiments of the sealing arrangement  40  employed for sealing the interface between the first open end  22  of the casing main body  12  and the first end cover  16  of the reciprocating compressors  10  shown in  FIGS. 1-4 . A circumferential lip  42  on the first open end  22  of the casing main body  12  surrounds the end opening and defines a first radially facing circumferential surface  46 . The first end cover  16  has a circumferential lip  50  defining a second radially facing circumferential surface  52 . The first circumferential surface  46  and the second circumferential surface  52  interface along an endless circumferential interface. The sealing arrangement  40  includes a circumferentially extending groove  55 , having a base  54  and a side wall  57 , formed in one of the first and second radially extending circumferential surfaces  46 ,  52  and a sealing member  56  disposed within the circumferentially extending groove  55  in sealing contact with the base  54  thereof and in sealing contact with the other one of the first and second radially extending circumferentially extending surfaces  46 ,  52 . Additionally, the pressure within the interior of the compressor  10  acts to force the sealing member  56  in sealing contact with the side wall  57  of the circumferentially extending groove  55 . 
     In the embodiment of the sealing arrangement  40  depicted in  FIG. 5 , the circumferentially extending groove  55  is formed in the second radially facing surface  52  on the circumferential lip  50  of the first end cover  16 , and the sealing member  56  is disposed in the groove  55  in sealing contact with both the base  54  and the side wall  57  of the groove  55  and with the first radially facing circumferentially extending surface  46 . In the embodiment of the sealing arrangement  40  depicted in  FIG. 6 , the circumferentially extending groove  55  is formed in the first radially facing surface  46  on the circumferential lip  42  of the first open end  22  of the casing main body  12 , and the sealing member  56  is disposed in the groove  55  in sealing contact with both the base  54  and the side wall  57  of the groove  55  and with the second radially facing circumferentially extending surface  52 . 
     Referring now to  FIG. 7 , there is depicted an embodiment of the sealing arrangement  40  employed for sealing the interface between the second open end  24  of the casing main body  12  and the second end cover  18  of the reciprocating compressors  10  shown in  FIGS. 1-4 . A circumferential lip  44  on the second open end  24  of the casing main body  12  surrounds the end opening and defines a first radially facing circumferential surface  48 . The second end cover  18  has a circumferential lip  60  defining a second radially facing circumferential surface  62 . The first circumferential surface  48  and the second circumferential surface  62  interface along an endless circumferential interface. The sealing arrangement  40  includes a circumferentially extending groove  65 , having a base  64  and a side wall  67 , formed in one of the first and second radially extending circumferential surfaces  48 ,  62  and a sealing member  66  disposed within the circumferentially extending groove  65  in sealing contact with the base  64  thereof and in sealing contact with the other one of the first and second radially extending circumferentially extending surfaces  48 ,  62 . Additionally, the pressure within the interior of the compressor  10  acts to force the sealing member  56  in sealing contact with the side wall  57  of the circumferentially extending groove  55 . 
     In the embodiment of the sealing arrangement  40  depicted in  FIG. 7 , the circumferentially extending groove  65  is, as described above, formed in the second radially facing surface  62  on the circumferential lip  60  of the second casing end cover  18 , and the sealing member  66  is disposed in the groove  65  in sealing contact with both the base  64  and the side wall  67  of the groove  65  and with the first radially facing circumferentially extending surface  48  on the circumferential lip  44  on the second end  24  of the casing main body  12 . However, in alternative embodiment of the sealing arrangement  40  (not depicted in  FIG. 7 ), the circumferentially extending groove  65  could be formed in the first radially facing surface  48  on the circumferential lip  44  of the second end  24  of the casing main body  12 , and the sealing member  66  disposed in the groove  65  in sealing contact with both the base  64  and the side wall  67  of the groove  65  and with the second radially facing circumferentially extending surface  62 . 
     Referring now to  FIG. 8 , another embodiment of the sealing arrangement  40  is depicted wherein the sealing member is disposed in an endless circumferentially extending pocket established by overlapping circumferentially extending recesses, one of the recesses formed in one of the first and second radially facing circumferentially extending surfaces and the other of the recesses formed in the other of the first and second radially facing circumferentially extending surfaces. For example, as illustrated in  FIG. 8 , a first circumferentially extending recess  70 , having a radially facing base surface  72 , is formed in the second radially facing circumferentially extending surface  62  of the circumferential lip  60  on the second casing end cover  18  and a second circumferentially extending recess  74 , having a radially facing base surface  78 , is formed in the first radially facing circumferentially extending surface  48  on the circumferential lip  44  on the second open end  24  of the main casing  12 . 
     Each of the first and second recesses  70 ,  74  are in effect grooves having an open side and one side wall. The first recess  70  is open at the axial end surface of the circumferential lip  60  and the second recess  74  is open at the axial end surface of the circumferential lip  44 . When the second casing end cover  18  is mated to the second open end  24  of the casing main body  12 , the first and second recesses  70 ,  74  overlap to form an endless circumferentially extending pocket  75 . To seal the interface between the first radially facing circumferentially extending surface  48  and the second radially facing circumferentially extending surface  62 , a sealing member  76  is disposed within the pocket  75 . When disposed in the pocket  75 , the sealing member  76  is in sealing contact with both the base surface  72  of the first recess  70  and the base surface  76  of the second recess  74 . Additionally, the pressure within the interior of the compressor  10  acts to force the sealing member  76  in sealing contact with the side wall  77  of the circumferentially extending recess  70 . 
     In the embodiments depicted in  FIGS. 5 and 6 , the circumferential lip  42  of the first open end  22  of the main casing  12  circumscribes the circumferential lip  50  on the first casing end cover  16 . However, in  FIGS. 9-11 , embodiments of the sealing arrangement  40  as disclosed herein are shown installed on a semi-hermetic compressor  10  wherein the first casing end cover  16  has a circumferential lip  50  that circumscribes the circumferential lip  42  on the first open end  22  of the casing main body  12   
     In the embodiment depicted in  FIG. 9 , the circumferentially extending groove  55  is formed in the second radially facing surface  52  on the circumferential lip  50  of the first casing end cover  16 , and the sealing member  56  is disposed in the groove  55  in sealing contact with both the base  54  of the groove  55  and the first radially facing circumferentially extending surface  46  on the circumferential lip  42  of the first open end  22  of the casing main body  12 . Additionally, the pressure within the interior of the compressor  10  acts to force the sealing member  56  in sealing contact with the side wall of the circumferentially extending groove  55 . 
     In the embodiment depicted in  FIG. 10 , the circumferentially extending groove  50  is formed in the first radially facing surface  46  on the circumferential lip  42  of the first open end  22  of the casing main body  12 , and the sealing member  56  is disposed in the grove  55  in sealing contact with both the base  54  of the groove  55  and the second radially facing circumferentially extending surface  52  on the circumferential lip  50  of the first casing end cover  16 . Additionally, the pressure within the interior of the compressor  10  acts to force the sealing member  56  in sealing contact with the side wall of the circumferentially extending groove  55 . 
     In the embodiment depicted in  FIG. 11 , a circumferentially extending recess  70  is formed the radially outward facing surface of the distal end of the circumferential lip  42  on the first open end  22  of the casing main body  12  whereby the recess  70  has an open end side. When the casing end cover  16  is placed over the open end of the first open end  22  of the casing main body  12 , the circumferential lip  50  on the first casing end cover  16  circumscribes and interfaces with the circumferential lip  42  of the casing main body  12 , whereby a pocket  75  is formed by the recess  70  and the radially inwardly facing surface  72  and axially inwardly facing surface  79  on the casing end cover  16 . To seal the interface, the sealing member  76  is disposed within the pocket  75  in sealing contact with the base of the recess  70  and the radially inwardly facing surface  72  on the casing end cover  16 . Additionally, the pressure within the interior of the compressor  10  acts to force the sealing member  76  in sealing contact with the axially inwardly facing surface  79  on the casing end cover  16 . 
     In the embodiment depicted in  FIG. 11 , the pocket  75  is established by a single recess  70  interfacing with the radially inwardly facing surface on the circumferential lip  50  on the casing end cover  16 . However, it is to be understood, that the pocket  75  could also be establishing by interfacing a first recess having an open end side formed in the radially outwardly facing surface of the circumferential lip  42  on the casing main body  12  in alignment with a second recess having an open end side formed in the radially inwardly facing surface of the circumferential lip  50  on the casing end cover  16 , similarly to the arrangement depicted in  FIG. 8 . 
     The sealing arrangement  40 , discussed hereinbefore with respect to the various embodiments shown in  FIGS. 5-11 , provides a seal for sealing the interface between the first and second open ends  22 ,  24  of the casing main body  12  and the first and second casing end covers  16 ,  18 , respectively, that is more robust than a conventional face seal gasket disposed between two opposed axially facing surfaces. The seal arrangement  40  disclosed herein establishes a seal between two radially facing circumferentially extending surfaces that overlap axially along an endless circumferentially extending interface, one of the radially facing circumferentially extending surfaces being a circumscribing surface and the other of the radially facing circumferentially extending surfaces being a circumscribed surface. 
     The seal is provided by a sealing member captured in an endless circumferentially extending groove formed in one of the radially facing circumferentially extending surfaces, or captured within each of a pair of opposed endless circumferentially extending grooves, one groove formed in each of the radially facing circumferentially extending grooves, or captured in a pocket formed by overlapping recesses formed in the respective first and second circumferentially extending surfaces. Therefore, the area of machined and polished surfaces required for contacting the sealing member is much smaller than the contact area that must be provide, machined and polished on both the end faces of the first and second ends  22 ,  24  of the casing main body  12  and also on the faces of first and second casing end covers  16 ,  18  to establish an effective gasket face seal, thereby simplifying the manufacturing of the compressor  10 . 
     Additionally, the sealing arrangement  40  simplifies the mounting of the casing end covers  16 ,  18  to the respective open ends  22 ,  24  of the casing main body  12 . Only four bolts are required to mount each casing end cap to a respective open end of casing main body when the sealing arrangement  40  is employed, as compared to a conventional semi-hermetic compressor wherein ten to eighteen bolts may be required to mount a casing end cover to an end of the casing main body in such manner as to establish a tight gasket seal therebetween. Further, the need for a large flange on each of the casing end covers and each of the casing main body to support such a large number of mounting bolts is avoided, thereby permitting the designer to reduce the overall foot print of the compressor. 
     The sealing members  56 ,  66 ,  76  may comprise any sealing material suitable for deposition in an endless circumferentially extending groove to establish an effective seal of the interface between two opposed radially facing circumferentially extending surfaces. For example, in an embodiment, the sealing member  56 ,  66 ,  76  may comprise an elastomeric material, and in an embodiment comprises an elastomeric O-ring seal. The axial dimension of the groove(s)/pocket may be wider than the sealing member  56 ,  66 ,  76  thereby allowing for some flex between the casing end cover and the casing main body. 
     The terminology used herein is for the purpose of description, not limitation. Specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as basis for teaching one skilled in the art to employ the present invention. Those skilled in the art will also recognize the equivalents that may be substituted for elements described with reference to the exemplary embodiments disclosed herein without departing from the scope of the present invention. 
     While the present invention has been particularly shown and described with reference to the exemplary embodiments as illustrated in the drawing, it will be recognized by those skilled in the art that various modifications may be made without departing from the spirit and scope of the invention. Therefore, it is intended that the present disclosure not be limited to the particular embodiment(s) disclosed as, but that the disclosure will include all embodiments falling within the scope of the appended claims.