Patent Publication Number: US-8535029-B2

Title: Scroll type compressor having reinforced fixed scroll

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a scroll type compressor. 
     In general, a scroll type compressor includes a fixed scroll member having a fixed end plate and a fixed scroll wall and a movable scroll member having a movable end plate and a movable scroll wall. The fixed and the movable scroll members are disposed in a housing of the compressor with the scroll walls thereof engaged with each other. The movable scroll member orbits around the axis of the fixed scroll member and refrigerant gas drawn into a compression chamber formed between the fixed and the movable scroll walls of the scroll members is compressed with a decrease in the volume of the compression chamber in accordance with the orbital motion of the movable scroll member relative to the fixed scroll member. 
     Japanese Patent Application Publications H9-273488 and H11-148470 disclose a scroll type compressor that has a rib provided on the side of the fixed end plate that is opposite from the side thereof where the fixed scroll wall is formed. Japanese Patent Application Publication H9-273488 disclose a scroll type compressor having a first rib provided at the center on one side of the fixed end plate, a plurality of second ribs provided on the same side of the fixed end plate and extending radially from the first rib and a third rib provided adjacently to the outer periphery of the fixed end plate and connected with the second ribs. Japanese Patent Application Publication H11-148470 disclose a scroll type compressor having a first rib provided on one side of the fixed end plate so as to surround the discharge port and a plurality of second ribs extending radially from the first rib. 
     In the scroll type compressors of the above Publications, the compression chamber formed between the fixed and the movable scroll walls of the scroll members is moved toward the center while reducing its volume in accordance with the orbital motion of the movable scroll member. Refrigerant in the compression chamber is compressed and discharged out therefrom through the discharge port into a discharge chamber. The compressed and hence high-pressure refrigerant is used in the refrigerant circuit for the air conditioning. The ribs in the scroll type compressors disclosed in the above-cited Publications prevent the fixed scroll member from being deformed by the compressed high-pressure refrigerant. 
     Japanese Patent Application Publication 2006-118511 discloses a scroll type compressor that has the discharge chamber and an oil storage chamber between the housing and the fixed scroll member. In this scroll type compressor, the discharge chamber and the oil storage chamber are separated from each other by a separation wall formed behind the fixed end plate and a separation wall formed in the front of the housing. 
     In a scroll type compressor, it is difficult to strike a balance between increasing the amount of the refrigerant discharged per one orbital motion of the movable scroll member and the on-board capability. 
     If the winding angle of the fixed scroll wall and the movable scroll wall is increased with an attempt to increase the amount of the refrigerant discharged per one orbital motion of the movable scroll member, the size of the compressor is enlarged only for the sacrifice of the on-board capability. Meanwhile, if the height of the fixed scroll wall and the movable scroll wall is enlarged with an attempt to increase the amount of the refrigerant discharged per one orbital motion of the movable scroll member, there is a fear that the strength of the center portion of the movable scroll member and fixed scroll member may be impaired. If the thickness of the fixed end plate and the movable end plate is enlarged for the increasing the strength of the center portion of the movable scroll member and fixed scroll member, the size of the compressor is enlarged and, therefore, the on-board capability is impaired. 
     In the scroll type compressor of the above Publication, the rib or the separation wall of the fixed end plate is provided irrespective of the inner end of the fixed scroll wall. Therefore, there has been a problem in that the size of the compressor is enlarged and the on-board capability is decreased. 
     The present invention is directed to providing a scroll type compressor that can strike a balance between increasing the amount of refrigerant discharged per one orbital motion of the movable scroll member and the on-board capability. 
     SUMMARY OF THE INVENTION 
     A scroll type compressor has a rotary shaft, a fixed scroll member, a movable scroll member and a rib. The fixed scroll member has a fixed end plate and a fixed scroll wall. The fixed end plate has first and second sides. The fixed scroll wall is formed on the first side. The movable scroll member has a movable end plate and a movable scroll wall. The movable scroll wall is formed on the movable end plate. The movable scroll member is adapted to make an orbital motion in accordance with the rotation of the rotary shaft whereby a compression chamber to decrease the volume of the compression chamber with the orbital motion of the movable scroll member is formed between the fixed scroll member and the movable scroll member. The rib is provided on the second side at an opposite area where the inner end of the fixed scroll wall is located. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features of the present invention that are believed to be novel are set forth with particularity in the appended claims. The invention together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which; 
         FIG. 1  is a longitudinal sectional view of a scroll type compressor according to a first embodiment of the present invention; 
         FIG. 2  is a rear view of a fixed scroll member of the scroll type compressor of  FIG. 1 ; 
         FIG. 3  is a rear view of a fixed scroll member of a scroll type compressor according to a second embodiment of the present invention; 
         FIG. 4  is a rear view of a fixed scroll member of a scroll type compressor according to a third embodiment of the present invention; 
         FIG. 5  is a rear view of a fixed scroll member of a scroll type compressor according to a fourth embodiment of the present invention; 
         FIG. 6  is a rear view of a fixed scroll member of a scroll type compressor according to a fifth embodiment of the present invention; 
         FIG. 7  is a rear view of a fixed scroll member of a scroll type compressor according to a sixth embodiment of the present invention; and 
         FIG. 8  is a rear view of a fixed scroll member of a scroll type compressor according to a seventh embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following will describe the first embodiment of a scroll type compressor used for a vehicle air conditioner according to the present invention with reference to  FIGS. 1 and 2 . In the following description, the references to directions of front and rear are indicated by double-head arrow T 1  in  FIG. 1 . 
     Referring to  FIG. 1 , the scroll type compressor  10  (hereinafter simply referred to simply as compressor) includes a front housing  5 , a fixed scroll member  1  and a rear housing  7 . The front housing  5 , the fixed scroll member  1  and the rear housing  7  are fixed to each other by a plurality of bolts (not shown). An O-ring  9  is disposed between the front housing  5  and the fixed scroll member  1 . A gasket  11  is arranged between the rear housing  7  and the fixed scroll member  1 . 
     The front housing  5  has formed therethrough a shaft hole  5 A. A rotary shaft  21  is rotatably mounted in the shaft hole  5 A of the front housing  5  through a seal device  17  and a bearing  19 . The seal device  17  and the bearing  19  are retained by snap rings  18 ,  20  in the shaft hole  5 A, respectively. The rotary shaft  21  has an eccentric key  21 A that is offset from the center axis O of the rotary shaft  21 . The eccentric key  21 A is fitted in a bush  25  and retained by a circlip  23 . The bush  25  is formed integrally with a counterweight  25 A. A movable scroll member  3  is rotatably supported by the bush  25  through a bearing  27 . 
     The fixed scroll member  1  includes a disk-shaped fixed end plate  13  disposed perpendicularly to the center axis O and having the front side  13 B as a first side of the fixed end plate  13 , a fixed scroll wall  15  extending frontward from the front side  13 B and a fixed peripheral wall  14  extending frontward from the periphery of the front side  13 B of the fixed end plate  13 . As shown in  FIG. 2 , the fixed scroll wall  15  is formed extending spirally from the inner end  15 A to the outer end  15 B on the fixed scroll wall  15 , e.g., along an involute curve. The inner end  15 A is the initial part of the spiral curve of the fixed scroll wall  15 . The fluid pressure adjacent to the inner end  15 A is highest, so that the inner end  15 A of the fixed scroll wall  15  is formed thicker than the outer end  15 B. The surface of the inner end  15 A is rounded, as shown in  FIG. 2 . As shown in  FIG. 1 , a tip seal  15 C is provided in the tip of the fixed scroll wall  15 . 
     The movable scroll member  3  includes a disk-shaped movable end plate  29  extending perpendicularly to the center axis O, a movable scroll wall  31  extending rearward from the rear side  29 A of the movable end plate  29  and having an outer end  31 B. The movable scroll wall  31  is formed extending spirally from the inner end  31 A to the outer end  31 B on the movable scroll wall  31 , e.g., along an involute curve. The fluid pressure adjacent to the inner end  31 A is highest, so that the inner end  31 A of the movable scroll wall  31  is formed thicker than the outer end  31 B. A tip seal  31 C is provided in the tip of the movable scroll wall  31 . The movable scroll wall  31  of the movable scroll member  3  engages with the fixed scroll wall  15  of the fixed scroll member  1 , thus a compression chamber  2  being defined by the fixed end plate  13 , the fixed scroll wall  15 , the movable end plate  29  and the movable scroll wall  31 . 
     A plurality of stationary pins  37  is fixed in the rear end of the front housing  5  in parallel relation to the center axis O. The same number of movable pins  35  as the stationary pins  37  is fixed in the movable end plate  29  in parallel relation to the center axis O. The same number of rings  33  as the stationary pins  37  is provided between the front housing  5  and the movable end plate  29 . Each stationary pin  37  is disposed with one end thereof inserted in the front housing  5  and the other end thereof inserted through its corresponding ring  33 . Each movable pin  35  disposed with one end thereof inserted in the movable end plate  29  and the other end thereof inserted through its corresponding ring  33 . The stationary pins  37 , the movable pins  35 , and the rings  33  cooperate to form a rotation preventing mechanism that prevents the rotation of the movable scroll member  3  on its axis and allows the movable scroll member  3  to orbit around the center axis O. 
     The fixed scroll member  1  and the rear housing  7  define therebetween a discharge chamber  41  and an oil storage chamber  43 . An oil separation chamber  42  is formed in the rear housing  7 . The fixed end plate  13  has formed therethrough at a position adjacent to the inner end  15 A of the fixed scroll wall  15  a discharge port  13 A. The discharge chamber  41  is communicable through the discharge port  13 A with the innermost compression chamber  2 . The discharge port  13 A has an opening  40  in a rear side  13 C as a second side of the fixed end plate  13 . The discharge port  13 A is opened and closed by a discharge valve  16 A which is fixed to the rear side  13 C of the fixed end plate  13  by a pin  16 C. Opening of the discharge valve  16 A is regulated by a retainer  16 B fixed to the rear side  13 C by the pin  16 C. 
     The oil separation chamber  42  is formed cylindrical, and an oil separator  44  is provided in the oil separation chamber  42 . The discharge chamber  41  communicates with the oil separation chamber  42  through a communication hole  7 A. The communication hole  7 A is formed in facing relation to the oil separator  44 . An outlet port  44 A is provided to the upper end of the oil separator  44 . The oil separation chamber  42  communicates with an external refrigerant circuit (not shown) through the outlet port  44 A. The external refrigerant circuit includes a condenser, an expansion valve, and an evaporator and communicates with an inlet port (not shown) of the compressor  10 . 
     The oil separation chamber  42  is in communication with the oil storage chamber  43  through a communication hole  7 B. It is so arranged that oil in the oil storage chamber  43  is supplied to the sliding surfaces between the fixed scroll wall  15  and the movable end plate  29  and also between the movable scroll wall  31  and the fixed end plate  13  through an oil supply passage (not shown). 
     As shown in  FIG. 2 , the fixed end plate  13  is formed integrally therewith on the rear side  13 C thereof with a rib  39 A that projects rearward from the fixed end plate  13  and extends substantially radially to the outer periphery of the fixed end plate  13  and also behind the inner end  15 A of the fixed scroll wall  15  without surrounding the discharge port  13 A. The opening  40  is arranged between an end portion  50  of the rib  39 A and the compression chamber  2 . As shown in  FIG. 1 , the rear housing  7  is formed integrally therewith an auxiliary rib  7 C so as to support the rib  39 A from behind through the gasket  11 . The oil storage chamber  43  is separated from the discharge chamber  41  by the rib  39 A and the auxiliary rib  7 C. Illustration of the discharge valve  16 A, the retainer  16 B, and the pin  16 C is omitted in  FIG. 2 . The same holds true of  FIGS. 3-8  which will be described hereinafter. 
     The rotary shaft  21  is driven by a pulley (not shown) through an electromagnetic clutch (not shown). When the rotary shaft  21  is rotated, the movable scroll member  3  orbits around the center axis O through the eccentric key  21 A, the bush  25 , and the rotation preventing mechanism. Refrigerant gas is introduced into a compression chamber  2  through a suction port (not shown), and compressed with a decrease in the volume of the compression chamber  2  in accordance with the orbital motion of the movable scroll member  3 . After being compressed to the desired pressure in the center of the compression chamber  2 , the refrigerant gas is discharged into the discharge chamber  41  through the discharge port  13 A. The refrigerant gas in the discharge chamber  41  is flowed into the oil separation chamber  42  through the communication hole  7 A. The oil contained in the refrigerant gas is separated therefrom in the oil separation chamber  42  and flowed into the oil storage chamber  43  through the communication hole  7 B. The refrigerant gas having separated the oil therefrom is supplied to the refrigerant circuit to be used for air conditioning the vehicle. 
     The inner end  15 A and the rib  39 A provided on the rear side  13 C of the fixed end plate  13  so as to extend behind the inner end  15 A of the fixed scroll wall  15 , as shown in  FIG. 2 , cooperate to reinforce the fixed end plate  13  with the inner end  15 A. Therefore, the fixed end plate  13  can be formed less thick than in the prior art and the compressor  10  can be made smaller in the axial length, accordingly. 
     Consequently, the dimensions of the fixed scroll wall  15  and the movable scroll wall  31  as measured in axial direction of the compressor may be increased without enlarging the winding angle of the fixed scroll wall  15  and the movable scroll wall  31 , as shown in  FIG. 1 , the amount of the refrigerant discharged per one orbital motion of the movable scroll member  3  can be increased. It is also possible to prevent the compressor on-board capability from being decreased due to an increased axial length of the fixed end plate  13 . 
     The arrangement of the rib  39 A that extends around the discharge port  13 A helps to prevent an increase of the axial length of the discharge port  13 A. The dead volume of the compression chamber  2  is reduced, thus further improving the efficiency of the compressor. 
     The rib  39 A extending to the outer periphery of the fixed end plate  13  serves to additionally reinforce the end plate  13 . Furthermore, the thickness of the fixed end plate  13  can be additionally reduced, so that the axial length of the compressor  10  can be additionally reduced. 
     The auxiliary rib  7 C provided on the rear housing  7  to support the rib  39 A through the gasket  11  cooperate with the rib  39 A to additionally reinforce the end plate  13 . Furthermore, the thickness of the fixed end plate  13  can be additionally reduced and the axial length of the compressor  10  can be additionally reduced, accordingly. 
     The oil storage chamber  43  is separated from the discharge chamber  41  by the rib  39 A and the auxiliary rib  7 C, so that the rib  39 A functions as a separation wall separating the oil storage chamber  43  from the discharge chamber  41 . It is not necessary to provide a separation wall in addition to the rib  39 A. 
     The following will describe the second embodiment according to the present invention with reference to  FIG. 3 . The following description will use the same reference numerals for the common elements or components in the first and the second embodiments, and the description of such elements and components in  FIG. 3  for the second embodiment will be omitted. As shown in  FIG. 3 , the scroll type compressor of the second embodiment differs from the counterpart of the first embodiment in that the fixed end plate  13  is formed integrally therewith on the rear side  13 C thereof with an island shaped rib  39 B. Only the discharge chamber  41  is formed in the surroundings of the rib  39 B. The rib  39 B is formed with a thickness in the radial direction that is larger than the thickness of the inner end  15 A in the radial direction. 
     Unlike the rib  39 A in the first embodiment, the rib  39 B does not extend to the outer periphery of the fixed end plate  13 . The rib  39 B of the second embodiment is formed thick enough to reinforce the fixed end plate  13 . The rest of the effects according to the second embodiment are same as those according to the first embodiment. 
     The following will describe the third embodiment according to the present invention with reference to  FIG. 4 . The following description will use the same reference numerals for the common elements or components in the first and the third embodiments, and the description of such elements and components in  FIG. 4  for the third embodiment will be omitted. As shown in  FIG. 4 , the fixed end plate  13  is formed integrally therewith on the rear side  13 C thereof with a rib  39 C. One end of the rib  39 C is formed arcuate and arranged along the inner end  15 A of the fixed scroll wall  15 . The other end of the rib  39 C extends to the outer periphery of the fixed end plate  13 . Only the discharge chamber  41  is formed in the surroundings of the rib  39 C. 
     The rib  39 C having the other end thereof extending to the outer periphery of the fixed end plate  13  is strong enough to reinforce the fixed end plate  13 . Furthermore, the rib  39 C having the one end thereof arranged along the inner end  15 A has a strength that is enough to reinforce the fixed end plate  13 . The rest of the effects according to the third embodiment are same as those according to the first embodiment. 
     The following will describe the fourth embodiment according to the present invention with reference to  FIG. 5 . The following description will use the same reference numerals for the common elements or components in the first and fourth embodiments, and the description of such elements and components in  FIG. 5  for the fourth embodiment will be omitted. As shown in  FIG. 5 , the fixed end plate  13  is formed integrally therewith on the rear side  13 C thereof with a rib  39 D. The rib  39 D includes a center portion that is substantially formed arcuate and arranged along the inner end  15 A of the fixed scroll wall  15  and substantially straight portions that extend in opposite directions from the center portion to the outer periphery of the fixed end plate  13 . The oil storage chamber  43  is separated from the discharge chamber  41  by the rib  39 D. The fixed end plate  13  is reinforced enough by the rib  39 D. The rest of the effects according to the fourth embodiment are same as those according to the first and third embodiments. 
     The following will describe the fifth embodiment according to the present invention with reference to  FIG. 6 . The following description will use the same reference numerals for the common elements or components in the first and fifth embodiments, and the description of such elements and components in  FIG. 6  for the fifth embodiment will be omitted. As shown in  FIG. 6 , the shape of a rib  39 E of the fifth embodiment is different from that of the rib  39 D of the fourth embodiment. Specifically, the rib  39 E has a center portion that is formed arcuate and arranged along the inner end  15 A of the fixed scroll wall  15  and substantially straight portions extending from the opposite ends of the arcuate center portion of the rib  39 E to the outer periphery of the fixed end plate  13 . The oil storage chamber  43  is separated from the discharge chamber  41  by the rib  39 E. 
     The rib  39 E having the opposite ends thereof connected to the outer periphery of the fixed end plate  13  reduces the load at the ends as compared with the rib  39 D of the fourth embodiment and reinforces the fixed end plate  13 , accordingly. The rest of the effects according to the fourth embodiment are same as those according to the first and third embodiments. 
     The following will describe the sixth embodiment according to the present invention with reference to  FIG. 7 . The following description will use the same reference numerals for the common elements or components in the first and sixth embodiments, and the description of such elements and components in  FIG. 7  for the sixth embodiment will be omitted. As shown in  FIG. 7 , the fixed end plate  13  is formed integrally therewith on the rear side  13 C thereof with a rib  39 F. Specifically, the rib  39 F has a center portion that is formed arcuate and arranged along the inner end  15 A of the fixed scroll wall  15  and a straight portion that extends from the center arcuate portion to the outer periphery of the fixed end plate  13 . Only the discharge chamber  41  is formed in the surroundings of the rib  39 F. The fixed end plate  13  is reinforced enough by the rib  39 F. The rest of the effects according to the fourth embodiment are same as those according to the first and third embodiments. 
     The following will describe the seventh embodiment according to the present invention with reference to  FIG. 8 . The following description will use the same reference numerals for the common elements or components in the first and seventh embodiments, and the description of such elements and components in  FIG. 8  for the seventh embodiment will be omitted. As shown in  FIG. 8 , the shape of a rib  39 G is different from the shape of the rib  39 F. Specifically, the rib  39 G has a center portion that is formed arcuate and arranged along the inner end  15 A and two straight portions extending from the arcuate center portion to the outer periphery of the fixed end plate  13 , respectively. The two straight portions of the rib  39 G extend in perpendicular relation to each other. The oil storage chamber  43  is separated from the discharge chamber  41  by the rib  39 G The fixed end plate  13  is reinforced enough by the rib  39 G. The rest of the effects according to the fourth embodiment are same as those according to the first and third embodiments. 
     The above embodiments may be modified in various ways as exemplified below. 
     In the above-described embodiments, the rotary shaft  21  is driven by the pulley through the electromagnetic clutch. Alternatively, the rotary shaft  21  may be driven by an electric motor provided in the compressor. 
     In the above-described embodiments, the inner ends  15 A,  31 A of the fixed scroll wall  15  and the movable scroll wall  31  are formed thicker than the outer ends  15 B,  31 B. Alternatively, the inner ends  15 A,  31 A may be formed otherwise. 
     Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein but may be modified within the scope of the appended claims.