Patent Publication Number: US-2013228982-A1

Title: Sealing structure for compressor

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a sealing structure for a compressor. 
     2. Description of Related Art 
     As disclosed in a Japanese Patent Application Laid-Open No. 2007-92710 (Patent Document 1), a general compressor includes a cylindrical housing whose one end is opened so as to form an opening and a header which is fixed to the housing so as to close the opening of the housing. Main components (e.g. a compression unit) of the compressor are accommodated in the housing. 
     The opening of the housing is sealed by fixing the header to the housing using bolts aligned along a circumferential direction of the housing at even intervals. In addition, an O-ring is installed between the housing and the header to securely seal the opening of the housing. 
     A gland (groove) into which the O-ring is installed is formed on an end face around the opening of the housing. The end face is separated, by the gland, into an outer face on an outer circumferential side and an inner face on an inner circumferential side. In a prior-art sealing structure for a compressor, both of the outer face and the inner face are included in a single plane. 
     SUMMARY OF THE INVENTION 
     However, according to the above prior-art sealing structure, a fastening force by the bolts is strong near the bolts, but becomes weak at a middle of each two contiguous bolts. Therefore, the fastening force is not even along the circumferential direction of the housing. As a result, refrigerant with which an inside of the housing is filled may undesirably leak out from portions where the fastening force is weak. 
     In addition, the end face around the opening of the housing is not worked with a flattening process, so that the end face may not be finely flat but slightly rough. The slight roughness may reduce sealing performance between the housing and the header, so that refrigerant may undesirably leak out from the inside of the housing. 
     An object of the present invention is to provide a sealing structure that can improve sealing performance between a housing and a header of a compressor. 
     An aspect of the present invention provides a sealing structure for a compressor that includes a cylindrical housing in which a compression unit is accommodated, one end of the housing being opened so as to form an opening, a header fixed to the housing to close the opening of the housing, a ring-shaped gland formed on an end face any one of the housing and the header, an O-ring installed in the gland to seal between the housing and the header, and a fastening mechanism for fixing the header to the housing, wherein the end face is separated, by the gland, into an outer face on an outer circumferential side and an inner face on an inner circumferential side, and a step is formed between the outer face and the inner face. 
     According to the aspect, in a case where the gland is formed on the housing, only one of the outer face and the inner face is contacted with the end face of the header due to the step. On the other hand, in another case where the gland is formed on the header, only one of the outer face and the inner face is contacted with the end face of the housing due to the step. In both cases, a contacting area between the end face of the housing and the end face of the header is reduced. A fastening force by the fastening mechanism can be applied only to the contacting area, so that the fastening force (a pressing force per unit area) for fixing the header to the housing can be enhanced. As a result, a refrigerant leakage from a contacted plane between the housing and the header can be prevented securely. 
     It is preferable that one of the outer face and the inner face on a side of which the fastening mechanism is provided is protruded from a plane of another of the outer face and the inner face so as to form the step. 
     According to this configuration, in a case where the fastening mechanism is provided on a side of the outer face, the outer face is protruded from a plane of the inner face so as to form the step. On the other hand, in another case where the fastening mechanism is provided on a side of the inner face, the inner face is protruded from a plane of the outer face so as to form the step. In both cases, advantages according to the above-explained aspect of the present invention can be brought by a simple structure. 
     Here, it is preferable that the fastening mechanism is provided on a side of the outer face. 
     According to this configuration, the fastening mechanism is provided on the side of the outer face, so that the outer face is protruded from a plane of the inner face so as to form the step. Therefore, the O-ring is sealed within the compressor and not exposed to an environment outside the compressor. As a result, durability of the O-ring can be improved. 
     It is preferable that a suction port for suctioning refrigerant into an inside of the housing or a discharge port for discharging refrigerant from an inside of the housing is provided nearby the opening on the inner face of the housing, and the O-ring includes an expanded portion for surrounding the suction port or the discharge port. 
     According to this configuration, the suction port or the discharge port can be also sealed by the sealing structure in addition to the opening of the housing. Note that, as adopted in this configuration, the O-ring can take a modified shape other than a precise circular shape. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of a compressor including a sealing structure according to an embodiment (a cross-sectional view taken along a line I-I shown in  FIG. 2 ); 
         FIG. 2  is a front view of an end face of a housing of the compressor; and 
         FIG. 3  is a partially enlarged cross-sectional view of the housing; 
         FIG. 4  is a further enlarged cross-sectional view of the housing; and 
         FIG. 5  is an enlarged cross-sectional view showing a state where a header is fixed to the housing. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENT 
     Hereinafter, a sealing structure according to an embodiment will be explained with reference to the drawings. 
     As shown in  FIGS. 1 to 4 , a compressor  1  is provided with a sealing structure according to the present embodiment. The sealing structure includes a cylindrical housing  2 , a header  3 , an O-ring  5 , and a fastening mechanism (bolts  7 , through holes  10  and bolt holes  11 ). One end of the housing  2  is opened so as to form an opening  6 , and another end of the housing  2  is bottomed (closed). A compression unit  4  for compressing refrigerant is accommodated in an inside of the housing  2 . The header  3  closes the opening  6  of the housing  2 . The O-ring  5  is installed between the housing  2  and the header  3 . The bolts  7  are served as the fastening mechanism for fixing the header  3  to the housing  2 . 
     A gland  19  is formed on an end face  17  of the housing  2 . The O-ring  5  is installed within the gland  19 . The gland  19  has a ring-shaped path associated with a circumferential shape of the end face  17 . The end face  17  is separated, by the gland  19 , into an outer face  21  on an outer circumferential side and an inner face  23  on an inner circumferential side. A suction port  15  for suctioning refrigerant into the housing  2  is also formed on the end face  17  (the inner face  23 ). Note that a depth of the gland  19  is determined in view of a deformation (compression) of the O-ring  5  to be installed in the gland  19 . 
     Bolt holes  11  are formed on the outer face  21 . The bolt holes  11  are also served as the fastening mechanism. The six bolt holes  11  are formed along a circumferential direction of the housing at even intervals. Note that, although the six bolt holes  11  are formed in the present embodiment, less-than or more-than six bolt holes  11  may be formed as long as the header  3  can be fixed to the housing  2  firmly. 
     A portion of the inner face  23  on an inner side of the gland  19  is enlarged outward so as to form an enlarged portion  25 , and the above-mentioned suction port  15  is formed on the enlarged portion  25 . The suction port  15  communicating with the inside of the housing  2  is opened at the inner face  23 . Refrigerant (not shown) circulating in a refrigeration cycle is suctioned into the housing  2  through the suction port  15 . 
     The header  3  fixed to the housing  2  by the fastening mechanism is formed so as to have an outline shape almost identical to an outline shape of the end face  17  of the housing  2  in order to close the opening  6  of the housing  2 . The header  3  is fixed to the housing  2  in a state where the outer face  21  is being contacted with an end face  9  of the header  3 . In the state, the O-ring  5  is deformed between a bottom of the gland  19  and the end face  9  of the header  3  (see  FIG. 5 ). Through holes  10  are also formed on the header  3 . The through holes  10  are also served as the above-mentioned fastening mechanism. Namely, the fastening mechanism in the present embodiment includes the bolts  7 , the bolt holes  11  on the housing  2 , and the through holes  10  on the header  3 . 
     The O-ring  5  installed between the housing  2  and the header  3  is made of elastic material such as rubber, and formed so as to have a shape identical to the gland  19 . Similarly to the gland  19 , a portion of the O-ring  5  is expanded outward so as to form an expanded portion  13 . The expanded portion  13  is matched with the enlarged portion  25  to seal the suction port  15 . 
     As shown in  FIGS. 3 to 5 , a minute step is provided between the outer face  21  and the inner face  23  so that the outer face  21  slightly protrudes toward the header  3  from a plane of the inner face  23 . In other words, a minute gap is formed between the inner face  23  of the housing  2  and the end face  9  of the header  3  when the header  3  is fixed to the housing  2 . A height H of the step (a width H of the gap) is preferably set to 0.2 mm in order to ensure a sealing performance (an adequate deformation) of the O-ring  5 . 
     Next, processes for assembling the header  3  with the housing  2  will be explained. 
     First, the O-ring  5  is installed in the gland  19  on the housing  2 . The end face  9  of the header  3  is approached toward the end face  17  of the housing  2 , so that the O-ring  5  is firstly contacted with the end face  9  of the header  3 . The header  3  is further approached toward the housing  2 , so that the outer face  21  of the housing  2  is contacted with the end face  9  of the header  3  with the O-ring  5  being deformed. In a state where the outer face  21  is being contacted with the end face  9 , the bolts  7  are inserted through the through holes  10  and fixed to the bolt holes  11 , respectively. Namely, the header  3  is fixed to the housing  2  by the fastening mechanism. 
     Sealing performance can be secured by a first contact between the outer face  21  of the housing  2  and the end face  9  of the header  3  and a second contact between the deformed (compressed) O-ring  5  and the end face  9  of the header  3 . 
     According to the present embodiment, the step is formed between the outer face  21  and the inner face  23  so as to protrude the outer face  21  toward the header  3  (the gap is formed between the inner face  23  and the end face  9 ), so that only the outer face  21  contacts with the header  3 . Therefore, a contacting area between the end face  17  of the housing  2  and the end face  9  of the header  3  is reduced. A fastening force by the fastening mechanism can be applied only to the contacting area, so that the fastening force (a pressing force per unit area) for fixing the header  3  to the housing  2  can be enhanced. As a result, a refrigerant leakage from a contacted plane between the housing  2  and the header  3  can be prevented securely. 
     In the above embodiment, the fastening mechanism is constructed on a side of the outer face  21  instead of the inner face  23  and the outer face  21  is protruded toward the header  3 . Therefore, the fastening force by the fastening mechanism can be improved more securely and thereby sealing characteristics by the sealing structure can be secured. 
     In addition, the contacting face between the outer face  21  and the end face  9  can be ensured due to the improved fastening force. Therefore, the fastening force by the fastening mechanism can be applied only to the contacting area between the housing  2  and the header  3  to secure the sealing performance by the sealing structure. Further, the O-ring is sealed within the compressor and not exposed to an environment outside the compressor. As a result, durability of the O-ring can be improved. 
     Furthermore, the suction port  15  is provided on the enlarged portion  25  nearby the opening  6  of the housing  2 , and the O-ring  5  has the expanded portion  13  for surrounding the suction port  15 . Therefore, the suction port  15  can be also sealed by the sealing structure in addition to the opening  6 . Note that, as shown in the above embodiment, the O-ring  5  can take a modified shape other than a precise circular shape. 
     Note that the present invention is not limited to the above embodiment and can take various modification within a technical scope of the present invention. For example, the suction port  15  is formed nearby the opening  6  of the housing  2  in the above embodiment, but the present invention may be applied to a sealing structure for sealing a discharge port formed nearby the opening  6 . 
     In addition, the outer face  21  is protruded toward the header  3  instead of the inner face  23  in the above embodiment. However, the inner face  23  may be protruded toward the header  3  rather than the outer face  21 . Further, the fastening mechanism may be constructed on a side of the inner face  23 . 
     Further, in the above embodiment, the O-ring  5  is installed in the gland  19  formed on the housing  2 . However, the gland  19  may be formed on the header  3 . In this case, the step (i.e. the outer face and the inner face) may be formed on the header  3 . Namely, in this case, one of the outer face and the inner face of the header  3  may be protruded toward the housing  2  so as to form the step.