Patent Publication Number: US-2007101859-A1

Title: Compressor

Description:
CROSS REFERENCE TO RELATED APPLICATIONS AND INCORPORATION BY REFERENCE  
      This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2005-0321101, filed on Nov. 4, 2005; the entire contents of which are incorporated herein by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a compressor, and, more particularly, to a compressor useable in a refrigeration cycle of a vehicular air conditioner or the like to compress refrigerant.  
      2. Description of the Related Art  
      As a conventional compressor, for example, there is a wobble plate type variable displacement compressor disclosed in Japanese Patent Application Laid-Open No. 2000-320455. The wobble plate type variable displacement compressor includes a shaft, a rotating base for integral rotation with the shaft, a wobble plate that is rotatably attached to the rotating base via a radial bearing and a thrust bearing, and pistons connected to an outer region of the wobble plate via pairs of hemispherical-shaped shoes. When the rotating base integrally rotates with the shaft, the wobble plate wobbles in a manner corresponding to the inclination angle of the rotating base, so that the pistons reciprocate.  
      The wobble plate does not rotate rapidly due to the friction with the shoes. Accordingly, the wobble plate type compressor has an advantage that the rotation moment (the torque) is small and the friction between the shoes and the wobble plate is low, compared to a swash plate type compressor in which a swash plate integrally rotates with a shaft.  
     SUMMARY OF THE INVENTION  
      In the wobble plate type compressor, a compression reaction force from the pistons is applied to an area around the upper dead center of the wobble plate. The compression reaction force is set off from the center of the shaft (the center of the wobble plate) so that the wobble plate is pressed in such a manner that the wobble plate inclines with respect to the rotating base. Accordingly, the strong force is applied to an outer region of the thrust bearing located between the wobble plate and the rotating base. This force causes the outer region of rolling elements of the thrust baring to be subjected to excessive wear.  
      Japanese Patent Application Laid-Open No. 2003-328931 suggests locating a thrust bearing on an axial line of the pistons to receive the compression reaction force from the pistons. This location requires a large thrust bearing so that a flange formed on the rotating base and a flange formed on the wobble plate that sandwich the larger thrust bearing also have a large size.  
      The present invention was developed based on such a problem of the related art and provides a compressor in which damage of an outer region of a thrust bearing, caused by a compression reaction force, can be prevented without enlarging the size.  
      The first aspect of the present invention is a compressor including a thrust bearing having a pair of races; a first member and a second member sandwiching the thrust bearing therebetween; and a release portion that allows flexing of an outer region of one of races of the thrust bearing.  
      The second aspect of the present invention is a compressor including a thrust bearing; a first member and a second member sandwiching the thrust bearing therebetween; a first thrust receiving face formed on the first member and receiving the thrust bearing; and a second thrust receiving face formed on the second member and receiving the thrust bearing, at least one of the first thrust receiving face and second thrust receiving face being out of contact with an outer region of the thrust bearing.  
      The third aspect of the present invention is a compressor including a shaft; a rotating base configured to rotate with the shaft and having a first thrust receiving face; a wobble plate having a second thrust receiving face; a thrust bearing sandwiched between the first thrust receiving face and the second thrust receiving face such that the wobble plate is rotatable relative to the rotating base; and a piston engaged with the wobble plate for reciprocation corresponding to wobble movement of the wobble plate. One of the first thrust receiving face and the second thrust receiving face is out of contact with an outer region of the thrust bearing.  
      The fourth aspect of the present invention is a compressor including a compressor housing having a first thrust receiving face; a shaft rotatably supported by the housing; a rotor fixed to the shaft to rotate with the shaft and having a second thrust receiving face; a piston configured to reciprocate corresponding to rotation of the rotor; and a thrust bearing sandwiched between the first thrust receiving face and the second thrust receiving face. One of the first thrust receiving face and the second thrust receiving face is out of contact with an outer region of the thrust bearing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a cross-sectional view showing a compressor according to a first embodiment of the present invention;  
       FIG. 2  is an enlarged sectional view showing a connecting structure between a wobble plate and a rotating base of the compressor;  
       FIG. 3  is an enlarged sectional view showing a connecting structure between a wobble plate and a rotating base of a compressor according to a second embodiment;  
       FIG. 4  is an enlarged sectional view showing a connecting structure between a wobble plate and a rotating base of a compressor according to a third embodiment;  
       FIG. 5  is an enlarged sectional view showing a connecting structure between a wobble plate and a rotating base of a compressor according to a fourth embodiment;  
       FIG. 6  is an enlarged sectional view showing a connecting structure between a wobble plate and a rotating base of a compressor according to a fifth embodiment; and  
       FIG. 7  is an enlarged sectional view showing a connecting structure between a housing and a rotor of a compressor according to a sixth embodiment. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      A compressor according to embodiments of the present invention will be described with reference to the drawings.  
     First Embodiment  
       FIG. 1  is an overall cross-sectional view showing a compressor according to the first embodiment. As shown in  FIG. 1 , the compressor  1  of the first embodiment is a wobble plate type variable displacement compressor. The compressor  1  includes a cylinder block  2  having a plurality of cylinder bores  3  located evenly spaced apart in a circumferential direction, a front head  4  attached to a front end of the cylinder block  2  and having a crank chamber  5  therein, and a rear head  6  attached to a rear end of the cylinder block  2  via a valve plate  9  and having a suction chamber  7  and a discharge chamber  8  therein. The cylinder block  2 , the front head  4 , and the rear head  6  are fixed to each other by a plurality of bolts  13  so as to compose a housing of the compressor.  
      The valve plate  9  has suction ports (not shown) that allow the cylinder bores  3  to communicate with the suction chamber  7  and discharge ports  12  that allow the cylinder bores  3  to communicate with the discharge chamber  8 .  
      A valve system (not shown) adapted to open and close the suction ports is provided on the valve plate  9  at the cylinder block side. A valve system (not shown) adapted to open and close the discharge ports  12  is provided on the valve plate  9  at the rear head side.  
      A drive shaft  10  is supported by radial bearings  17 ,  18  in support bores or holes  19 ,  20  that are formed at central portions of the cylinder block  2  and the front head  4  so that the drive shaft  10  is rotatable in the crank chamber  5 . A thrust bearing  16  is interposed between a thrust receiving face  83  of a rotor  21 , fixed to the shaft  10 , and a thrust receiving face  81  of the front head  4 . A thrust bearing  15  is interposed between a step (thrust receiving face) formed on the support bore  19  of the cylinder block  2  and a step (thrust receiving face) formed on the shaft  10 .  
      The crank chamber  5  accommodates the rotor  21  fixed to the shaft  10 , a sleeve  22  attached to the shaft  10  slidable in the axial direction, a rotating base  25  connected to the sleeve  22 , such a ball joint structure, so as to be tiltable with respect to the axis of the shaft  10 , a wobble plate  26  attached to the rotating base  25  via a radial bearing  63  and a thrust bearing  61  so as to be rotatable in a circumferential direction with respect to he rotating base  25 , and a linkage mechanism  40  linking the rotor  21  and the rotating base  25  to transfer the rotation of the rotor  21  to the rotating base  25  as allowing changes of the inclination angle of the rotating base  25 .  
      Pistons  29  are reciprocatably disposed in the cylinder bores  3 . Each piston  29  is connected to the outer region of the wobble plate  26  via a pair of hemispherical-shaped piston shoes  30 .  
      With this structure, when the rotor  21  rotates with the shaft  10 , the rotation of the rotor  21  is transferred to the rotating base  25  via the linkage mechanism  40  so that the rotating base  25  rotates with the rotor  21 . When the rotating base  25  rotates, the wobble plate  26  wobbles corresponding to the inclination angle of a flange  25   b  of the rotating base  25 , but dose not rotate due to a sliding friction contact with the piston shoes  30 . The wobble of the wobble plate  26  is converted into reciprocation of the pistons  29 . By the reciprocation of the pistons  29 , refrigerant is sucked from the suction chamber  7  into the cylinder bores  3  through the suction ports of the valve plate  9 , and compressed in the cylinder bore  3 , and discharged to the discharge chamber  8  through the discharge ports  12  of the valve plate  9 .  
      The compressor  1  of the present embodiment is not a double-ended wobble plate type variable displacement compressor in which the pistons  29  are provided on both sides of the wobble plate  26 . The present compressor is a single-ended wobble plate type variable displacement compressor on which the pistons  29  are provided in one side of the wobble plate  26 .  
      Control of Variable Capacity  
      The inclination angle of the wobble plate  26  is changeable. When the wobble plate  26  is moved toward the cylinder block  2  against the return spring  52 , the inclination angle of the wobble plate  26  decreases. On the other hand, when the wobble plate  26  is moved away from the cylinder block  2  against the return spring  51 , the inclination angle of the wobble plate  26  increases.  
      The inclination angle of the wobble plate  26  corresponds to the piston strokes and the discharging amount of the compressor  1 . A pressure difference (pressure balance) between the crank chamber pressure Pc, in back of the pistons  29 , and the suction chamber pressure Ps, in front of the pistons  29 , makes a change in the inclination angle of the wobble plate  26  to change piston strokes. Accordingly, the compressor  1  has a pressure control mechanism. The pressure control mechanism includes a gas extraction passage (not shown) that allows the crank chamber  5  to communicate with the suction chamber  7 , a gas supply passage (not shown) that allows the crank chamber  5  to communicate with the discharge chamber  8 , and a control valve  33  that is provided in the midstream of the gas supply passage to open and close the gas supply passage.  
      Connecting Structure Between Wobble Plate and Rotating Base  
      A connecting structure between the wobble plate and the rotating base will be described with reference to  FIGS. 1 and 2 .  
      As shown in  FIGS. 1 and 2 , the rotating base  25  is formed with a substantially disk-like shaped flange  25   b  and a substantially tubular shaped boss  25   a . The wobble plate  26  is connected to the flange  25   b  via the thrust bearing  61  and to the boss  25   a  via the radial baring  63 . The wobble plate  26  is attached to the rotating base  25  under a precompression provided in a direction of the thrust load by a washer  65  and an adjusting screw  67 .  
      The radial bearing  63  includes a pair of races  63   a ,  63   b , balls  63   c  as rolling elements for rolling between the pair of races  63   a ,  63   b , and a retainer  63   d  for retaining the balls  63   c  between the pair of races  63   a ,  63   b . The thrust bearing  61  includes a pair of races  61   a ,  61   b , a plurality of column shaped needles  61   c  as rolling elements for rolling between the pair of races  61   a ,  61   b , and a retainer  61   d  retaining the needles  61   d  between the pair of races  61   a ,  61   b.    
      The compression reaction force Fp applied to the upper dead center of the wobble plate  26  or the area around the upper dead center is set off from the axis of the shaft  10 , so that a thrust load between the rotating base  25  and the wobble plate  26  is off center from the axis of them. In other words, the rotating base  25  and the wobble plate  26  relatively rotate in a condition in which the wobble plate  26  is pressed in an inclined manner with respect to the rotating base  25 . Therefore, outer regions of the needles  61   c  of the thrust bearing  61  are strongly pressed between the races  61   a ,  61   b . As a result, the needles  61   c  may be subjected to excessive wear.  
      In order to prevent such damage of the needles  61   c , an outer region of the race  61   a  is made so as to not contact with a thrust receiving face  71 . In other words, the trust receiving face  71  of the rotating base  25  has a slot or release portion  75  which allows flexure of the outer region of the race  61   a . The release portion  75  is defined by a recess  76  (a stepped portion  76  in this embodiment) which is formed on the thrust receiving face  71  of the rotating base  25  at an area corresponding to the outer region of the race  61   a . The recess  76  is recessed from the other parts of the thrust receiving face  71 . The recess  76  is formed in an annular shape along the outer region of the thrust bearing  61  and located at an inner side from outer ends of the needles  61   c.    
      Effect  
      With the above described structure, the first embodiment achieves about the following effects.  
      (1) According to the present embodiment, the outer region of the race  61   a  of the thrust bearing  61  does not contact the thrust receiving face  71 . In other words, the compressor  1  of the present embodiment includes the release portion  75  that allows elastic deformation of the outer region of the race  61   a  of the thrust bearing  61 .  
      Such a structure prevents the outer regions of the needles  61   c  from being damaged by pressure from the races  61   a ,  61   b  since the end of the thrust bearing  61  is deformable even when the rotating base  25  and the wobble plate  26  relatively rotate in such a manner that the wobble plate  26  inclines relative to the rotating base  25  by the compression reaction force Fp applied around the upper dead center of the wobble plate  26 .  
      (2) According to the present embodiment, the release portion  75  is defined by the recess (the stepped portion  76  in this embodiment) which is recessed from the thrust receiving face  71  of the rotating base  25  at an area corresponding to the outer region of the race  61   a . Accordingly, the release portion  75  can comprise a simple structure.  
     Second Embodiment  
      In the first embodiment, a release portion  75  is defined by a recess (a stepped portion  76 ) which is formed on the thrust receiving face  71  of the rotating base  25  at an area corresponding to the outer region of the race  61   a . However, for example, as shown in the second embodiment in  FIG. 3 , a recess may be provided as a linear slope  76 B.  
     Third Embodiment  
      As shown in the third embodiment in  FIG. 4 , a recess may be provided as a curved slope  76 C.  
     Fourth Embodiment  
      In the first embodiment, a release portion  75  is formed on only a thrust receiving face  71  of a rotating base  25 . However, for example, as shown in the fourth embodiment in  FIG. 5 , a release portion  77  may be formed, as a stepped portion  78  or the like, on a thrust receiving face  73  of a wobble plate  26  in addition to the release portion  75  formed on the thrust receiving face  71  of the rotating base  25 .  
     Fifth Embodiment  
      As shown in the fifth embodiment in  FIG. 6 , for example, release portions  79 ,  80  may be defined by forming outer ends of at least one of the races  61   a ,  61   b  and needles  61   c  to project from thrust receiving faces  71 ,  73 . In this case, the release portions can also comprise a simple structure.  
     Sixth Embodiment  
      In the above embodiments, the present invention is applied to a structure between the rotating base  25  and the wobble plate  26 , which relatively rotate while sandwiching a thrust bearing  61  therebetween. However, as shown in the sixth embodiment in  FIG. 7 , the present invention may be applied to a structure between a housing  4  of the compressor  1  and a rotor  21 , which relatively rotate while sandwiching a thrust bearing  16  therebetween. According to the sixth embodiment in  FIG. 7 , a recess (a stepped portion  86  in this embodiment) is formed on a thrust receiving face  81  of the housing  4 , not on a thrust receiving face  83  of a rotor  21 , so as to form a release portion  85 . With this structure, an outer region of a race  16 a, which contacts the thrust receiving face  81 , can be deformable.  
      As described above, a compressor according to the present invention includes a first member and a second member that are relatively rotate while sandwiching a thrust bearing therebetween and a release portion that allows deformation of an outer region of one of the races of the thrust bearing. In other words, one of a thrust receiving face of the first member and a thrust receiving face of the second member is not in contact with the outer region of the thrust bearing. This structure prevents a rotating element in the thrust bearing from being excessively worn, since the outer region of one of the races of the thrust bearing is allowed to be deformed even when the first member and the second member relatively rotate when a heavy load is applied to the outer region of the thrust races due to a pressure.  
      Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Modification and variation of the embodiments can be made without departing from sprit or scope of the appended claims. Therefore, the embodiments are only for illustrative purpose and not limit the invention.