Patent Publication Number: US-2016237994-A1

Title: Variable displacement swash-plate compressor

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a variable displacement swash-plate compressor. 
     Japanese Laid-Open Patent Publication No. 52-131204 discloses a variable displacement swash-plate compressor (hereinafter referred to as a compressor). This type of compressor includes a housing, a drive shaft, a swash plate, a link mechanism, single-headed pistons, a link mechanism, and a control mechanism. 
     The housing has a swash plate chamber, cylinder bores, and a discharge chamber. The drive shaft is rotationally supported by the housing. The swash plate is accommodated in the swash plate chamber to be rotational with the drive shaft. The link mechanism is located between the drive shaft and the swash plate. The link mechanism allows the inclination angle of the swash plate to be changed. The inclination angle is the angle of the swash plate in relation to a direction perpendicular to the axis of the drive shaft. The pistons are reciprocally accommodated in the cylinder bores. The conversion mechanism uses rotation of the swash plate to reciprocate the pistons in the cylinder bores by a stroke corresponding to the inclination angle. The inclination angle of the swash plate is changed by an actuator. The actuator is controlled by the control mechanism. 
     More specifically, the link mechanism includes a lug member, a hinge ball, and a link. The lug member is located in the swash plate chamber and is fixed to the drive shaft. The hinge ball is fitted about the drive shaft to be arranged between the swash plate and the drive shaft. The hinge ball includes a spherical portion, which slidably contacts the swash plate, and a receiving portion, which is located in the vicinity of the actuator. The receiving portion is an annular and flat surface arranged to be coaxial with the drive shaft. The link is provided between the lug member and the swash plate. The swash plate is pivotally connected to the lug member via the link. 
     The actuator includes the lug member, a movable body, and a control pressure chamber. The movable body has a cylindrical shape that is coaxial with and is fitted about the drive shaft. The movable body has an acting portion at a position in the vicinity of the hinge ball. The acting portion is an annular and flat surface coaxial with the drive shaft. The acting portion and the receiving portion contact each other in an area about the drive shaft. The movable body is thus engaged with the swash plate via the hinge ball. The control pressure chamber is defined by the lug member and the movable body. The pressure in the control pressure chamber moves the movable body along the axis of the drive shaft. The control mechanism uses a pressure regulation valve to regulate connection between the discharge chamber and the control pressure chamber, thereby increasing or decreasing the pressure in the control pressure chamber. 
     In this type of compressor, when the control mechanism controls and increases the pressure in the control pressure chamber, the movable body is moved along the axis so that the acting portion pushes the receiving portion along the axis. This moves the hinge ball along the axis so that the swash plate slides on the hinge ball in a direction for reducing the inclination angle. In contrast, when the control mechanism controls and decreases the pressure in the control pressure chamber, the movable body and the hinge ball are moved in a direction opposite to the above mentioned direction, so that the swash plate slides on the hinge ball in a direction for increasing the inclination angle. In this manner, by moving the movable body along the axis, the inclination angle of the swash plate is changed and the displacement per rotation of the drive shaft is increased or decreased. 
     In this type of compressor, the swash plate has a top dead center associated part for positioning each piston at the top dead center and a bottom dead center associated part for positioning each piston at the bottom dead center. The inclination angle of the swash plate is changed by pivoting the swash plate about the top dead center associated part without changing the top clearance of the pistons. The position at which the acting portion and the receiving portion contact each other has a structure described below. For example, the acting portion and the receiving portion contact each other in an area about the drive shaft as described above. In another structure, the acting portion and the receiving portion contact each other at a position that is closer to the top dead center associated part than the drive shaft in a direction perpendicular to the axis of the drive shaft. In this case, however, the contact position at which the acting portion and the receiving portion contact each other is close to the center of moment of the load acting on the swash plate. The contact position is also close to the top dead center associated part, at which the compression reaction force applied to the swash plate, for example, by the pistons is great. As a result, the load acting on the movable body is increased when the inclination angle is decreased. In this case, the inclination angle cannot be quickly changed in response to changes in the driving state, for example, of the vehicle, and high controllability cannot be achieved. 
     Thus, to increase the thrust of the movable body to act against such load, the pressure receiving area of the movable body may be increased. However, an increased pressure receiving area of the movable body increases the diameter of the actuator, which prevents the entire device from being reduced in size. 
     The contact position of the acting portion and the receiving portion may be changed to a position between the drive shaft and the bottom dead center associated part in the direction perpendicular to the axis of the drive shaft. In this case, the contact position is distant from the center of moment of the load acting on the swash plate, and the movable body receives little influence from the compression reaction force. As a result, the load acting on the movable body is decreased when the inclination angle is decreased. Thus, the inclination angle can be quickly changed in response to changes in the driving state, for example, of a vehicle, and high controllability is achieved. This, however, increases the stroke of the movable body when the inclination angle is changed. As a result, the axial dimension of the actuator is increased, hindering the entire device from being reduced in size. 
     SUMMARY OF THE INVENTION 
     An objective of the present invention is to provide a variable displacement swash-plate compressor that achieves high controllability and is reduced in size. 
     In accordance with one aspect of the present invention, and in accordance with one aspect of the present invention, a variable displacement swash-plate compressor is provided that includes a housing, in which a swash plate chamber and a cylinder bore are defined, a drive shaft rotationally supported by the housing, a swash plate rotational in the swash plate chamber by rotation of the drive shaft, a link mechanism, a piston, a conversion mechanism, an actuator, and a control mechanism. The link mechanism is arranged between the drive shaft and the swash plate. The link mechanism allows change of an inclination angle of the swash plate with respect to a direction perpendicular to an axis of the drive shaft. The piston is reciprocally received in the cylinder bore. The conversion mechanism causes the piston to reciprocate in the cylinder bore by a stroke corresponding to the inclination angle of the swash plate through rotation of the swash plate. The actuator is configured to change the inclination angle of the swash plate. The control mechanism controls the actuator. The link mechanism includes a lug member, which is located in the swash plate chamber and is fixed to the drive shaft, and a transmitting member, which transmits rotation of the lug member to the swash plate. The actuator includes the lug member, a movable body, and a control pressure chamber. The movable body is rotational integrally with the swash plate. The movable body is configured to change the inclination angle of the swash plate by moving along the axis of the drive shaft. The control pressure chamber is defined by the lug member and the movable body. The movable body is moved by changing a pressure in the control pressure chamber. The movable body has a primary acting portion and a secondary acting portion, which are configured to push the swash plate with the pressure in the control pressure chamber. The swash plate has a primary receiving portion and a secondary receiving portion, which are pushed by the primary acting portion and the secondary acting portion. A top dead center associated part for positioning the piston at a top dead center and a bottom dead center associated part for positioning the piston at the bottom dead center are defined on the swash plate. The primary acting portion is configured to contact the primary receiving portion to push the swash plate when the inclination angle of the swash plate is maximized. The secondary acting portion is configured to contact the secondary receiving portion to push the swash plate when the inclination angle of the swash plate is minimized. The secondary acting portion is located between the primary acting portion and the bottom dead center associated part. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of a compressor according to one embodiment, illustrating a state of the maximum displacement; 
         FIG. 2  is a block diagram showing the control mechanism of the compressor; 
         FIG. 3  is a front view of the swash plate of the compressor; 
         FIG. 4  is a rear view of the lug plate of the compressor; 
         FIG. 5  is a cross sectional side view showing the lug plate and the movable body assembled to the drive shaft of the compressor; 
         FIG. 6  is a cross sectional side view showing the movable body assembled to the drive shaft; 
         FIG. 7  is a rear view of the movable body; 
         FIG. 8  is an enlarged partial cross-sectional view showing the area including the movable body and the swash plate when the displacement is maximized; 
         FIG. 9  is an enlarged partial cross-sectional view showing the area including the movable body and the swash plate in a first inclination range; 
         FIG. 10  is an enlarged partial cross-sectional view showing the area including the movable body and the swash plate at the boundary between the first inclination range and a second inclination range; 
         FIG. 11  is an enlarged partial cross-sectional view showing the area including the movable body and the swash plate in the second inclination range; 
         FIG. 12  is an enlarged partial cross-sectional view showing the area including the movable body and the swash plate when the displacement is minimized; 
         FIG. 13  is an enlarged partial cross-sectional view showing the area including the movable body and the swash plate when displacement is maximized in a compressor of a comparison example; and 
         FIG. 14  is an enlarged partial cross-sectional view showing the area including the movable body and the swash plate when displacement is minimized in the compressor of the comparison example. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     One embodiment of the present invention will now be described with reference to the drawings. The compressor of the embodiment is a variable displacement swash-plate compressor with single-headed pistons. This compressor is installed in a vehicle and each included in the refrigeration circuit in the air conditioner of the vehicle. 
     As shown in  FIG. 1 , the compressor includes a housing  1 , a drive shaft  3 , a swash plate  5 , a link mechanism  7 , pistons  9 , pairs of shoes  11   a ,  11   b , an actuator  13 , and a control mechanism  15 , which is illustrated in  FIG. 2 . 
     As shown in  FIG. 1 , the housing  1  has a first housing member  17 , a second housing member  19 , a cylinder block  21 , and a valve assembly plate  23 . In the present embodiment, the front-rear direction is defined as shown in  FIG. 1 . 
     The first housing member  17  has a front wall  17   a , which extends radially, and a circumferential wall  17   b , which is integrated with the front wall  17   a  and extends rearward. A part of the first housing member  17  that is constituted by the front wall  17   a  and the circumferential wall  17   b  has a cylindrical shape with a closed end. The front wall  17   a  and the circumferential wall  17   b  define a swash plate chamber  25  in the first housing member  17 . 
     The front wall  17   a  has a boss  17   c , which projects forward. The boss  17   c  accommodates a shaft sealing device  27 . The boss  17   c  has a first shaft hole  17   d , which extends in the front-rear direction. The first shaft hole  17   d  accommodates a first plain bearing  29   a.    
     The circumferential wall  17   b  has an inlet  250 , which communicates with the swash plate chamber  25 . An evaporator  103  is connected to the inlet  250  via a pipe  203 . This allows low-pressure refrigerant gas delivered by the evaporator  103  to flow into the swash plate chamber  25  via the inlet  250 . Thus, the pressure in the swash plate chamber  25  is lower than that in a discharge chamber  35 , which will be discussed below. 
     A part of the control mechanism  15  is arranged in the second housing member  19 . The second housing member  19  has a first pressure regulation section  31   a , a suction chamber  33 , the discharge chamber  35 , a discharge passage  36 , and an outlet  360 . The first pressure regulation section  31   a  is located in the central part of the second housing member  19 . The discharge chamber  35  has an annular shape and is located in a radially outer part of the rear housing member  19 . The suction chamber  33  has an annular shape and is located between the first pressure regulation section  31   a  and the discharge chamber  35  in the second housing member  19 . 
     The discharge chamber  35  communicates with the outlet  360  via the discharge passage  36 . A condenser  101  is connected to the outlet  360  via a pipe  201 . A check valve  38  is provided in the discharge passage  36 . The check valve  38  is switchable between an open state and a closed state. Specifically, the check valve  38  is switched to the open state when the differential pressure of the discharge chamber  35  relative to the condenser  101  is greater than or equal to a predetermined value. In contrast, the check valve  38  is switched to the closed state when the differential pressure of the discharge chamber  35  relative to the condenser  101  is less than the predetermined value. When the check valve  38  is switched to the open state, the refrigerant gas in the discharge chamber  35  flows to the condenser  101  via the discharge passage  36 , the outlet  360 , and the pipe  201 . When the check valve  38  is switched to the closed state, refrigerant gas is prevented from flowing back from the condenser  101  to the discharge chamber  35 . 
     The cylinder block  21  includes cylinder bores  21   a , the number of which is the same as that of the pistons  9 . The cylinder bores  21   a  are arranged at equal angular intervals in the circumferential direction. The front end of the each cylinder bore  21   a  communicates with the swash plate chamber  25 . The cylinder block  21  also has retainer grooves  21   b , which limit the maximum opening degree of suction reed valves  41   a , which will be discussed below. 
     The cylinder block  21  further has a second shaft hole  21   c , which communicates with the swash plate chamber  25  and extends in the front-rear direction of the compressor. The second shaft hole  21   c  accommodates a second plain bearing  29   b . The first plain bearing  29   a  and the second plain bearing  29   b  may be replaced by rolling-element bearings. 
     The cylinder block  21  further has a spring chamber  21   d . The spring chamber  21   d  is located between the swash plate chamber  25  and the second shaft hole  21   c . The spring chamber  21   d  accommodates a restoration spring  37 . The restoration spring  37  urges the swash plate  5  forward when the inclination angle of the swash plate  5  is minimized. The cylinder block  21  also includes a suction passage  39 , which communicates with the swash plate chamber  25 . 
     The valve assembly plate  23  is located between the second housing member  19  and the cylinder block  21 . The valve assembly plate  23  includes a valve base plate  40 , a suction valve plate  41 , a discharge valve plate  43 , and a retainer plate  45 . 
     The valve base plate  40 , the discharge valve plate  43 , and the retainer plate  45  include suction ports  40   a , the number of which is equal to that of the cylinder bores  21   a . The valve base plate  40  and the suction valve plate  41  include discharge ports  40   b , the number of which is equal to that of the cylinder bores  21   a . The cylinder bores  21   a  communicate with the suction chamber  33  through the suction ports  40   a  and communicate with the discharge chamber  35  through the discharge ports  40   b . Furthermore, the valve base plate  40 , the suction valve plate  41 , the discharge valve plate  43 , and the retainer plate  45  include a first communication hole  40   c  and a second communication hole  40   d . The first communication hole  40   c  connects the suction chamber  33  to the suction passage  39 . This connects the swash plate chamber  25  to the suction chamber  33 . 
     The suction valve plate  41  is provided on the front surface of the valve base plate  40 . The suction valve plate  41  includes suction reed valves  41   a , which are allowed to selectively open and close the suction ports  40   a  by elastic deformation. The discharge valve plate  43  is located on the rear surface of the valve base plate  40 . The discharge valve plate  43  includes discharge reed valves  43   a , which are allowed to selectively open and close the discharge ports  40   b  by elastic deformation. The retainer plate  45  is provided on the rear surface of the discharge valve plate  43 . The retainer plate  45  limits the maximum opening degree of the discharge reed valves  43   a.    
     The drive shaft  3  has a cylindrical outer circumferential surface  30 . The drive shaft  3  is inserted in the boss  17   c  toward the rear of the housing  1 . The front end of the drive shaft  3  is supported by the shaft sealing device  27  in the boss  17   c  and is supported by the first plain bearing  29   a  in the first shaft hole  17   d . The rear end of the drive shaft  3  is supported by the second plain bearing  29   b  in the second shaft hole  21   c . In this manner, the drive shaft  3  is supported by the housing  1  to be rotational about the axis O. A second pressure regulation section  31   b  is defined in the second shaft hole  21   c  in a part rearward of the rear end of the drive shaft  3 . The second pressure regulation section  31   b  communicates with the first pressure regulation section  31   a  through the second communication hole  40   d . The first and second pressure regulation sections  31   a ,  31   b  constitute a pressure regulation chamber  31 . 
     O-rings  49   a ,  49   b  are provided on the rear end of the drive shaft  3 . The O-rings  49   a ,  49   b  are located between the drive shaft  3  and the circumferential wall of the second shaft hole  21   c  to seal off the swash plate chamber  25  and the pressure regulation chamber  31  from each other. 
     The link mechanism  7 , the swash plate  5 , and the actuator  13  are mounted to the drive shaft  3 . The link mechanism  7  includes first and second swash plate arms  5   e ,  5   f  provided on the swash plate  5  shown in  FIG. 3 , a lug plate  51  shown in  FIG. 4 , and first and second lug arms  53   a ,  53   b  provided on the lug plate  51 . The first and second swash plate arms  5   e ,  5   f  correspond to transmitting members of the present invention. The lug plate  51  corresponds to a lug member of the present invention. For illustrative purposes, part of the first swash plate arm  5   e  is omitted by using a break line in  FIG. 1 . The same applies to  FIGS. 8 to 14 , which will be discussed below. 
     As shown in  FIG. 3 , the swash plate  5  has a swash plate main portion  50 , a weight  5   c , and the first and second swash plate arms  5   e ,  5   f . The swash plate main portion  50  has an annular flat-plate like shape. As shown in  FIG. 1 , the swash plate main portion  50  has a front surface  5   a , which faces forward in the swash plate chamber  25 , and a rear surface  5   b , which faces rearward in the swash plate chamber  25 . As shown in  FIG. 3 , a top dead center associated part T for positioning each piston  9  at the top dead center and a bottom dead center associated part U for positioning each piston  9  at the bottom dead center are defined on the swash plate main portion  50 . Also, a bottom dead center plane D is defined in the swash plate main portion  50 . The bottom dead center plane D includes the top dead center associated part T, the bottom dead center associated part U, and the drive shaft axis O. Further, a first direction A 1  is defined in the swash plate main portion  50  as indicated by the solid arrow. The first direction A 1  is perpendicular to the axis O of the drive shaft  3  and is directed from the top dead center associated part T toward the bottom dead center associated part U. 
     As viewed in  FIG. 3 , the right side of the bottom dead center plane D is defined as a first side, and the left side of the bottom dead center plane D is defined as a second side. 
     The swash plate main portion  50  includes a through-hole  5   d . The drive shaft  3  is inserted in the through-hole  5   d . Two flat guide surfaces  52   a ,  52   b  are provided in the through-hole  5   d . The guide surfaces  52   a ,  52   b  contact the outer circumferential surface  30  of the drive shaft  3 , which is inserted in the through-hole  5   d.    
     The swash plate main portion  50  has, on the front surface  5   a , a first-side primary receiving portion  60   a  and a second-side primary receiving portion  60   b . The first-side primary receiving portion  60   a  and the second-side primary receiving portion  60   b  are each formed to be flat. The first-side primary receiving portion  60   a  and the second-side primary receiving portion  60   b  are located between the weight  5   c  and the first and second swash plate arms  5   e ,  5   f . The first-side primary receiving portion  60   a  and the second-side primary receiving portion  60   b  are located on opposite sides of the bottom dead center plane D and have symmetrical shapes with respect to the bottom dead center plane D. 
     The weight  5   c  is located on the front surface  5   a  of the swash plate main portion  50  and is located between the drive shaft axis O and the bottom dead center associated part U. The weight  5   c  has a substantially semi-circular cylindrical shape. As shown in  FIG. 1 , the weight  5   c  extends from the front surface  5   a  of the swash plate main portion  50  toward a movable body  13   a . The weight  5   c  regulates the balance of weight of the swash plate  5 . 
     As shown in  FIG. 3 , a first-side secondary receiving portion  61   a  and a second-side secondary receiving portion  61   b  are provided on the distal end of the weight  5   c . The first-side secondary receiving portion  61   a  and the second-side secondary receiving portion  61   b  are located on opposite sides of the bottom dead center plane D at positions in the vicinity of the distal end of the weight  5   c  and have symmetrical shapes with respect to the bottom dead center plane D. Being located in the vicinity of the distal end of the weight  5   c , the first-side secondary receiving portion  61   a  and the second-side secondary receiving portion  61   b  are located closer to the bottom dead center associated part U than the first-side primary receiving portion  60   a  and the second-side primary receiving portion  60   b  in the first direction A 1 . 
     The weight  5   c  has a first-side recess  62   a , which is continuous with the first-side secondary receiving portion  61   a , and a second-side recess  62   b , which is continuous with the second-side secondary receiving portion  61   b . As shown in  FIG. 1 , the first-side recess  62   a  is recessed from the first-side secondary receiving portion  61   a  toward the front surface  5   a . Although not illustrated, the second-side recess  62   b  is also recessed from the second-side secondary receiving portion  61   b  toward the front surface  5   a . As shown in  FIG. 3 , the first-side recess  62   a  and the second-side recess  62   b  are also located on opposite sides of the bottom dead center plane D and have symmetrical shapes with respect to the bottom dead center plane D. 
     The first and second swash plate arms  5   e ,  5   f  are located on the front surface  5   a  of the swash plate main portion  50  and between the axis O of the drive shaft  3  and the top dead center associated part T. The first swash plate arm  5   e  and the second swash plate arm  5   f  are arranged on opposite sides of the bottom dead center plane D. As shown in  FIG. 1 , the first and second swash plate arms  5   e ,  5   f  extend from the front surface  5   a  of the swash plate main portion  50  toward the lug plate  51 . 
     As shown in  FIG. 4 , the lug plate  51  has a substantially annular shape with a through-hole  510 . The drive shaft  3  is press fitted into the through-hole  510  of the lug plate  51 . This allows the lug plate  51  to rotate integrally with the drive shaft  3 . As shown in  FIG. 1 , a thrust bearing  55  is located between the lug plate  51  and the front wall  17   a.    
     As shown in  FIG. 5 , the lug plate  51  has a cylinder chamber  51   a . The cylinder chamber  51   a  is located on the same axis as the axis O of the drive shaft  3 . The chamber  51   a  has a cylindrical shape that extends forward from the rear end of the lug plate  51 . The rear end of the cylinder chamber  51   a  communicates with the swash plate chamber  25 . 
     As shown in  FIG. 4 , the first lug arm  53   a  and the second lug arm  53   b  are provided on the lug plate  51  at positions on opposite sides of the bottom dead center plane D. The first and second lug arms  53   a ,  53   b  are closer to the top dead center associated part T on the swash plate main portion  50  than the axis O of the drive shaft  3  and extend from the lug plate  51  toward the swash plate  5 . 
     The lug plate  51  has first and second guide surfaces  57   a ,  57   b  between the first and second lug arms  53   a ,  53   b . The first guide surface  57   a  and the second guide surface  57   b  are also located on opposite sides of the bottom dead center plane D. As shown in  FIG. 1 , the second guide surface  57   b  is inclined such that the distance from the swash plate  5  gradually decreases from the outer circumference of the lug plate  51  toward the cylinder chamber  51   a . The same applies to the first guide surface  57   a.    
     The first and second swash plate arms  5   e ,  5   f  are inserted between the first and second lug arms  53   a ,  53   b  to mount the swash plate  5  to the drive shaft  3 . The lug plate  51  and the swash plate  5  are thus coupled to each other with the first and second swash plate arms  5   e ,  5   f  located between the first and second lug arms  53   a ,  53   b . When rotation of the lug plate  51  is transmitted from the first and second lug arms  53   a ,  53   b  to the first and second swash plate arms  5   e ,  5   f , the swash plate  5  rotates with the lug plate  51  in the swash plate chamber  25 . 
     With the first and second swash plate arms  5   e ,  5   f  located between the first and second lug arms  53   a ,  53   b , the distal end of the first swash plate arm  5   e  contacts the first guide surface  57   a , and the distal end of the second swash plate arm  5   f  contacts the second guide surface  57   b . The first and second swash plate arms  5   e ,  5   f  slide on the first and second guide surfaces  57   a ,  57   b , respectively. Accordingly, the inclination angle of the swash plate  5  is allowed to change from the maximum inclination angle shown in  FIGS. 1 and 8  to the minimum inclination angle shown in  FIG. 12 , while substantially maintaining the position of the top dead center associated part T. 
     A first inclination range and a second inclination range are defined between the maximum inclination angle and the minimum inclination angle. The first inclination range is a range from an inclination angle close to the maximum inclination angle to the maximum inclination angle and includes the maximum inclination angle. On the other hand, the second inclination range is a range from the maximum inclination angle to the first inclination range and includes the minimum inclination angle. Specifically, the inclination angle of the swash plate  5  shown in  FIGS. 8 and 9  is in the first inclination range, and the inclination angle of the swash plate  5  shown in  FIGS. 11 and 12  is in the second inclination range. The inclination angle of the swash plate  5  shown in  FIG. 10  is at the boundary between the first inclination range and the second inclination range. 
     As shown in  FIG. 5 , the actuator  13  includes the lug plate  51 , the movable body  13   a , and a control pressure chamber  13   b.    
     As shown in  FIG. 6 , the movable body  13   a  is fitted about the drive shaft  3 . The movable body  13   a  is thus located between the lug plate  51  and the swash plate  5  to move along the drive shaft axis O while sliding on the drive shaft  3 . The movable body  13   a  has a substantially cylindrical shape coaxial with the drive shaft  3 . Specifically, as shown in  FIG. 7 , the movable body  13   a  includes a movable body main portion  130 , a first-side primary acting portion  70   a , a second-side primary acting portion  70   b , a first-side secondary acting portion  71   a , a second-side secondary acting portion  71   b , and a rotation stopper  134 . 
     As shown in  FIG. 6 , the movable body main portion  130  includes a first cylindrical portion  131 , a second cylindrical portion  132 , and a coupling portion  133 . The first cylindrical portion  131  is located at a position in the vicinity of the swash plate  5  in the movable body  13   a  and extends along the axis O of the drive shaft  3 . The first cylindrical portion  131  has the smallest diameter in the movable body main portion  130 . The first cylindrical portion  131  has a rear end face  131   a , the diameter of which gradually decreases toward the rear end. As shown in  FIG. 5 , a ring groove  131   b  is provided in the inner circumferential surface of the first cylindrical portion  131 . An O-ring  49   c  is fitted in the ring groove  131   b.    
     The second cylindrical portion  132  is located at a position on the movable body main portion  130  that is in the vicinity of the lug plate  51 , that is, at the front end of the movable body  13   a . The outer diameter of the second cylindrical portion  132  is greater than that of the first cylindrical portion  131  and is greatest in the movable body main portion  130 . The second cylindrical portion  132  has a flat front end face  132   a  and a flat rear end face  132   b . With the drive shaft  3  inserted in the movable body  13   a , the front end face  132   a  and the rear end face  132   b  of the movable body  13   a  are perpendicular to the axis O of the drive shaft  3 . The second cylindrical portion  132  has a ring groove  132   c  in the outer circumferential surface. An O-ring  49   d  is fitted in the ring groove  132   c.    
     The coupling portion  133  is formed to have a diameter that is gradually increased from the first cylindrical portion  131  toward the second cylindrical portion  132 . The coupling portion  133  couples the first cylindrical portion  131  to the rear end face  132   b  of the second cylindrical portion  132 . 
     As shown in  FIG. 7 , the first-side primary acting portion  70   a  and the second-side primary acting portion  70   b  are located on opposite sides of the bottom dead center plane D and at the rear end of a first cylindrical portion  131 . The first-side primary acting portion  70   a  and the second-side primary acting portion  70   b  have symmetrical shapes with respect to the bottom dead center plane D. The first-side primary acting portion  70   a  extends from the rear end of the first cylindrical portion  131  and toward the radially outer edge of the movable body  13   a . As shown in  FIG. 6 , the first-side primary acting portion  70   a  extends further rearward than the rear end face  131   a  of the first cylindrical portion  131 . As shown in  FIG. 7 , the rear end face of the first-side primary acting portion  70   a  is shaped as a cylinder with a generatrix extending in a direction perpendicular to the bottom dead center plane D. 
     The first-side secondary acting portion  71   a  and the second-side secondary acting portion  71   b  are formed on opposite sides of the bottom dead center plane D to extend over the rear end face  132   b  of the second cylindrical portion  132  and the coupling portion  133 . The first-side secondary acting portion  71   a  and the second-side secondary acting portion  71   b  have symmetrical shapes with respect to the bottom dead center plane D. As shown in  FIG. 6 , the first-side secondary acting portion  71   a  protrudes rearward from the rear end face  132   b  of the second cylindrical portion  132  and the coupling portion  133 . As shown in  FIG. 7 , the first-side secondary acting portion  71   a  extends further radially outward than the first-side primary acting portion  70   a  and the second-side primary acting portion  70   b . The rear end face of the second-side secondary acting portion  71   a  is shaped as a cylinder with a generatrix extending in a direction perpendicular to the bottom dead center plane D. 
     The first-side primary acting portion  70   a  and the second-side primary acting portion  70   b  are closer to the top dead center associated part T of the swash plate main portion  50  than the axis O of the drive shaft  3 . On the other hand, the first-side secondary acting portion  71   a  and the second-side secondary acting portion  71   b  are closer to the bottom dead center associated part U of the swash plate main portion  50  than the axis O of the drive shaft  3 . Accordingly, the first-side secondary acting portion  71   a  and the second-side secondary acting portion  71   b  are closer to the bottom dead center associated part U than the first-side primary acting portion  70   a  and the second-side primary acting portion  70   b  in the first direction A 1 . 
     The movable body  13   a  is located between the lug plate  51  and the swash plate  5  and moves along the axis O of the drive shaft  3 . This causes the first-side primary acting portion  70   a  and the second-side primary acting portion  70   b  to contact the first-side primary receiving portion  60   a  and the second-side primary receiving portion  60   b  shown in  FIG. 3 , respectively. Also, the first-side secondary acting portion  71   a  and the second-side secondary acting portion  71   b  shown in  FIG. 7  are brought into contact with the first-side secondary receiving portion  61   a  and the second-side secondary receiving portion  61   b , respectively. These contacting actions will be described below. 
     As shown in  FIG. 6 , the rotation stopper  134  is formed at the rear end of the first cylindrical portion  131 . The rotation stopper  134  has a rectangular shape as shown in  FIG. 7  and extends vertically from the first cylindrical portion  131  toward the top dead center associated part T of the swash plate main portion  50 . The rotation stopper  134  is located between the first swash plate arm  5   e  and the second swash plate arm  5   f , which are shown in  FIG. 3 . As the swash plate  5  rotates, the rotation stopper  134  contacts the first swash plate arm  5   e  or the second swash plate arm  5   f . That is, the rotation stopper  134  restricts pivoting motion of the movable body  13   a  about the axis O. This allows the movable body  13   a  to be rotated integrally with the lug plate  51  and the swash plate  5  by rotation of the drive shaft  3 . 
     As shown in  FIG. 5 , the control pressure chamber  13   b  is defined by the second cylindrical portion  132 , the coupling portion  133 , the cylinder chamber  51   a , and the drive shaft  3 . The control pressure chamber  13   b  and the swash plate chamber  25  are sealed off from each other by the O-rings  49   c ,  49   d.    
     The drive shaft  3  has an axial passage  3   a  and a radial passage  3   b . The axial passage  3   a  extends from the rear end of the drive shaft  3  toward the front end along the drive shaft axis O. The radial passage  3   b  extends in a radial direction from the front end of the axial passage  3   a  and opens in the outer circumferential surface  30  of the drive shaft  3 . As shown in  FIG. 1 , the rear end of the axial passage  3   a  communicates with the pressure regulation chamber  31 . The radial passage  3   b  communicates with control pressure chamber  13   b  as shown in  FIG. 5 . The axial passage  3   a  and the radial passage  3   b  connect the pressure regulation chamber  31  to the control pressure chamber  13   b.    
     As shown in  FIG. 1 , the drive shaft  3  has a threaded portion  3   c  at the front end. The drive shaft  3  is connected to a pulley (not shown) via the threaded portion  3   c.    
     The pistons  9  are single-headed pistons each having a head  90  only at the rear end. Each piston  9  is accommodated in the corresponding one of the cylinder bores  21   a  and is allowed to reciprocate in the cylinder bore  21   a . The head  90  of each piston  9  and the valve assembly plate  23  define a compression chamber  57  in the corresponding cylinder bore  21   a.    
     Each piston  9  has an engaging portion  9   a . Each engaging portion  9   a  accommodates a pair of hemispherical shoes  11   a ,  11   b . The shoes  11   a ,  11   b  correspond to a conversion mechanism of the present invention. Each shoe  11   a  slides on the front surface  5   a  of the swash plate main portion  50 . In contrast, each shoe  11   b  slides on the rear surface  5   b  of the swash plate main portion  50 . In this manner, the swash plate main portion  50  causes the shoes  11   a ,  11   b  to move along the front surface  5   a  and the rear surface  5   b . Accordingly, the shoes  11   a ,  11   b  convert rotation of the swash plate  5  into reciprocation of the pistons  9 , and the pistons  9  reciprocate in the cylinder bores  21   a  by a stroke corresponding to the inclination angle of the swash plate  5 . Instead of providing the shoes  11   a ,  11   b , a wobble plate type conversion mechanism may be employed, in which a wobble plate is provided on the rear surface  5   b  of the swash plate main portion  50  via a thrust bearing, and the wobble plate and the pistons  9  are connected to each other with connecting rods. 
     As shown in  FIG. 2 , the control mechanism  15  includes a low-pressure passage  15   a , a high-pressure passage  15   b , a control valve  15   c , an orifice  15   d , the axial passage  3   a , and the radial passage  3   b.    
     The low-pressure passage  15   a  is connected to the pressure regulation chamber  31  and the suction chamber  33 . The low-pressure passage  15   a , the axial passage  3   a , and the radial passage  3   b  connect the control pressure chamber  13   b , the pressure regulation chamber  31 , and the suction chamber  33  to one another. The high-pressure passage  15   b  is connected to the pressure regulation chamber  31  and the discharge chamber  35 . The high-pressure passage  15   b , the axial passage  3   a , and the radial passage  3   b  connect the control pressure chamber  13   b , the pressure regulation chamber  31 , and the discharge chamber  35  to one another. 
     The control valve  15   c  is arranged in the low-pressure passage  15   a . The low-pressure control valve  15   c  is configured to adjust the opening degree of the low-pressure passage  15   a  based on the pressure in the suction chamber  33 . The high-pressure passage  15   b  also has the orifice  15   d.    
     The inlet  250  shown in  FIG. 1  is connected to the pipe  203 , which is connected to the evaporator  103 , and the outlet  360  is connected to the pipe  201 , which is connected to the condenser  101 . The condenser  101  is connected to the evaporator  103  through a pipe  202  and an expansion valve  102 . The refrigeration circuit in the vehicle air conditioner is configured as described above. 
     When the drive shaft  3  rotates to rotate the swash plate  5 , the pistons  9  are reciprocated in the cylinder bores  21   a . Accordingly, the volume of each compression chamber  57  changes in accordance with the stroke of the pistons  9 . Thus, refrigerant gas is drawn into the swash plate chamber  25  from the evaporator  103  via the inlet  250  and then into the compression chambers  57  from the suction passage  39  via the suction chamber  33 . The refrigerant gas is then compressed in each compression chamber  57 . The refrigerant that is compressed in the compression chambers  57  is discharged to the discharge chamber  35  and is delivered to the condenser  101  through the outlet  360 . 
     The actuator  13  changes the inclination angle of the swash plate  5  to increase or decrease the stroke of the pistons  9 , thereby varying the displacement. 
     When changing the inclination angle of the swash plate  5  from the minimum inclination angle shown in  FIG. 12  to the maximum inclination angle shown in  FIG. 8 , that is, when increasing the stroke of the pistons  9  to increase the displacement, the control valve  15   c  of the control mechanism  15  shown in  FIG. 2  increases the opening degree of the low-pressure passage  15   a . This substantially equalizes the pressure in the pressure regulation chamber  31  and thus the pressure in the control pressure chamber  13   b  with the pressure in the suction chamber  33 . Thus, compression reaction force that acts on the swash plate  5  from the pistons  9  causes the movable body  13   a  to move along the axis O of the drive shaft  3  toward the lug plate  51  as shown in  FIG. 9 . 
     The compression reaction force acting on the swash plate  5  and the urging force of the restoration spring  37  cause the first and second swash plate arms  5   e ,  5   f  to slide on the first and second guide surfaces  57   a ,  57   b , respectively, to move away from the axis O of the drive shaft  3 . 
     The swash plate  5  thus increases the inclination angle by pivoting to bring the bottom dead center associated part U closer to the lug plate  51 , while substantially maintaining the position of the top dead center associated part T. As a result, the stroke of the pistons  9  is increased, so that the displacement of the compressor per rotation of the drive shaft  3  is increased. When the inclination angle of the swash plate  5  is maximized as shown in  FIG. 8 , the displacement of the compressor per rotation of the drive shaft  3  is maximized. In this state, the movable body  13   a  is at the deepest position in the cylinder chamber  51   a.    
     When the displacement is large as described above, the pressure in the discharge chamber  35  is high, and the differential pressure of the discharge chamber  35  relative to the condenser  101  becomes greater than or equal to the predetermined value. In this case, since the check valve  38  shown in  FIG. 1  is switched to the open state, the refrigerant gas in the discharge chamber  35  flows into the condenser  101 . 
     To reduce the displacement, the control valve  15   c  of the control mechanism  15  shown in  FIG. 2  reduces the opening degree of the low-pressure passage  15   a . This increases the pressure in the pressure regulation chamber  31 , so that the pressure in the control pressure chamber  13   b  is increased. Hereinafter, an example will be described with reference to  FIGS. 8 to 12 , in which the inclination angle of the swash plate  5  is changed from the maximum inclination angle to the minimum inclination angle. 
     When the inclination angle of the swash plate  5  is within the first inclination range, which includes the maximum inclination angle as shown in  FIGS. 8 and 9 , the first-side primary acting portion  70   a  contacts the first-side primary receiving portion  60   a . Likewise, the second-side primary acting portion  70   b  shown in  FIG. 7  contacts the second-side primary receiving portion  60   b  shown in  FIG. 3 . On the other hand, when the inclination angle of the swash plate  5  is in the first inclination range as shown in  FIGS. 8 and 9 , the first-side secondary acting portion  71   a  is located in the first-side recess  62   a  of the weight  5   c  and is distant from the first-side secondary receiving portion  61   a . The first-side secondary acting portion  71   a  does not contact the first-side secondary receiving portion  61   a . Likewise, the second-side secondary acting portion  71   b  shown in  FIG. 7  is located in the second-side recess  62   b  shown in  FIG. 3  and is distant from the second-side secondary receiving portion  61   b  shown in  FIG. 3 . The second-side secondary acting portion  71   b  does not contact the second-side secondary receiving portion  61   b . Hereinafter, the state will be referred to as a first contact state. 
     When the pressure in the control pressure chamber  13   b  is increased, the movable body  13   a , which is at the deepest position in the cylinder chamber  51   a  as shown in  FIG. 8 , is moved toward the swash plate  5  along the axis O in the cylinder chamber  51   a  as shown in  FIG. 9 . This causes the first-side primary acting portion  70   a  and the second-side primary acting portion  70   b  to push the first-side primary receiving portion  60   a  and the second-side primary receiving portion  60   b  rearward along the axis O, respectively. That is, the movable body  13   a  pushes the swash plate  5  in the swash plate chamber  25  rearward along the axis O via the first-side primary acting portion  70   a  and the second-side primary acting portion  70   b.    
     The swash plate  5  thus decreases the inclination angle by pivoting to moving the bottom dead center associated part U away from the lug plate  51 , while substantially maintaining the position of the top dead center associated part T as shown in  FIG. 9 . As a result, the stroke of the pistons  9  is decreased, so that the displacement of the compressor per rotation of the drive shaft  3  is decreased. 
     When the pressure in the control pressure chamber  13   b  is further increased, and the movable body  13   a  further pushes the swash plate  5  via the first-side primary acting portion  70   a  and the second-side primary acting portion  70   b , the swash plate  5  is displaced to the inclination angle that corresponds to the boundary between the first inclination range and the second inclination range as shown in  FIG. 10 . In other words, the inclination angle of the swash plate  5  is reduced to the inclination angle that corresponds to the boundary between the first inclination range and the second inclination range, so that the displacement of the compressor is further reduced. 
     When the inclination angle of the swash plate  5  reaches the boundary between the first inclination range and the second inclination range, the first-side primary acting portion  70   a  contacts the first-side primary receiving portion  60   a , and the first-side secondary acting portion  71   a  contacts the first-side secondary receiving portion  61   a . Likewise, the second-side primary acting portion  70   b  shown in  FIG. 7  contacts the second-side primary receiving portion  60   b  shown in  FIG. 3 , and the second-side secondary acting portion  71   b  contacts the second-side secondary receiving portion  61   b.    
     Also, when the inclination angle of the swash plate  5  is reduced to the inclination angle that corresponds to the boundary between the first inclination range and the second inclination range, so that the displacement of the compressor is reduced, the pressure in the discharge chamber  35  is lowered, and the differential pressure of the discharge chamber  35  relative to the condenser  101  falls below the predetermined value. This switches the check valve  38  shown in  FIG. 1  from the open state to the closed state to prevent the refrigerant gas in the discharge chamber  35  from flowing back to the condenser  101 . 
     When the pressure in the control pressure chamber  13   b  is further increased, the movable body  13   a  is moved further toward the swash plate  5  along the axis O in the cylinder chamber  51   a  as shown in  FIG. 11 , so that the inclination angle of the swash plate  5  reaches the second inclination range. 
     When the inclination angle of the swash plate  5  is within the second inclination range, which includes the minimum inclination angle as shown in  FIGS. 11 and 12 , the first-side secondary acting portion  71   a  contacts the first-side secondary receiving portion  61   a . Likewise, the second-side secondary acting portion  71   b  shown in  FIG. 7  contacts the second-side secondary receiving portion  61   b  shown in  FIG. 3 . On the other hand, when the inclination angle of the swash plate  5  is in the second inclination range as shown in  FIGS. 11 and 12 , the first-side primary acting portion  70   a  is distant from the first-side primary receiving portion  60   a . The first-side primary acting portion  70   a  thus does not contact the first-side primary receiving portion  60   a . Likewise, the second-side primary acting portion  70   b  shown in  FIG. 7  is distant from the second-side primary receiving portion  60   b  shown in  FIG. 3  and does not contact the second-side primary receiving portion  60   b . Hereinafter, the state will be referred to as a second contact state. 
     When the inclination angle of the swash plate  5  is within the second inclination range, the first-side secondary acting portion  71   a  and the second-side secondary acting portion  71   a  push the first-side secondary receiving portion  61   a  and the second-side secondary receiving portion  61   a  rearward along the axis O, respectively. This changes the inclination angle of the swash plate  5  to the minimum inclination angle as shown in  FIG. 12 . When the swash plate  5  is at the minimum inclination angle, the displacement of the compressor per rotation of the drive shaft  3  is minimized. In this state, the movable body  13   a  is at the rearmost position in the cylinder chamber  51   a.    
     As described above, in the first inclination range, the first-side primary acting portion  70   a  and the second-side primary acting portion  70   b  of the movable body  13   a  contact the first-side primary receiving portion  60   a  and the second-side primary receiving portion  60   h  of the swash plate main portion  50 , respectively. Also, in the second inclination range, the first-side secondary acting portion  71   a  and the second-side secondary acting portion  71   b  contact the first-side secondary receiving portion  61   a  and the second-side secondary receiving portion  61   b  of the weight  5   c , respectively. 
     The first-side secondary acting portion  71   a  and the second-side secondary acting portion  71   b  are located between the bottom dead center associated part U and the first-side and second-side primary acting portions  70   a ,  70   b  in the first direction A 1 . The positions at which the first-side secondary acting portion  71   a  and the second-side secondary acting portion  71   b  respectively contact the first-side secondary receiving portion  61   a  and the second-side secondary receiving portion  61   b  are distant from the center of moment of the load acting on the swash plate  5  and distant from the top dead center associated part T, at which the compression reaction force is great. On the other hand, the positions at which the first-side primary acting portion  70   a  and the second-side primary acting portion  70   b  respectively contact the first-side primary receiving portion  60   a  and the second-side primary receiving portion  60   b  are closer to the center of moment of the load acting on the swash plate  5  and closer to the top dead center associated part T, at which the compression reaction force is great, than the positions at which the first-side secondary acting portion  71   a  and the second-side secondary acting portion  71   b  respectively contact the first-side secondary receiving portion  61   a  and the second-side secondary receiving portion  61   b.    
     The first inclination range includes the maximum inclination angle and is close to the maximum inclination angle in the range of change of the inclination angle of the swash plate  5 . The closer to the maximum inclination angle the swash plate  5  is, the greater the displacement becomes. Accordingly, it becomes easier to increase the pressure in the control pressure chamber  13   b , and as a result, it becomes easier to increase the thrust of the movable body  13   a . The second inclination range includes the minimum inclination angle and is close to the minimum inclination angle in the range of change of the inclination angle of the swash plate  5 . The closer to the minimum inclination angle the swash plate  5  is, the smaller the displacement becomes. Accordingly, it becomes more difficult to increase the pressure in the control pressure chamber  13   b , and as a result, it becomes more difficult to increase the thrust of the movable body  13   a.    
     That is, in the first inclination range, in which it is easy to increase the thrust of the movable body  13   a , the first-side primary acting portion  70   a  and the second-side primary acting portion  70   b  respectively contact the first-side primary receiving portion  60   a  and the second-side primary receiving portion  60   b  at positions close to the center of moment of the load acting on the swash plate  5  and at positions close to the top dead center associated part T, at which the compression reaction force is great, so that the movable body  13   a  pushes the swash plate  5 . Thus, even if the load acting on the movable body  13   a  is increased when the inclination angle is reduced, an increase in the thrust of the movable body  13   a  allows the inclination angle to be quickly changed in response to changes in the driving state of the vehicle, so that a high controllability is achieved. In this case, the stroke of the movable body  13   a  when changing the inclination angle is reduced. This allows the axial dimension of the actuator  13  to be reduced. 
     This operation will be described based on a comparison example. As shown in  FIGS. 13 and 14 , a compressor of the comparison example does not have the first-side primary acting portion  70   a  or the second-side primary acting portion  70   b  on the movable body  13   a . Also, the weight  5   c  of the swash plate  5  does not have the first-side recess  62   a  or the second-side recess  62   b . Accordingly, in the compressor of the comparison example, the first-side secondary acting portion  71   a  and the second-side secondary acting portion  71   b  always contact the weight  5   c  regardless of the inclination angle of the swash plate  5 . 
     In the compressor of the comparison example, when the inclination angle of the swash plate  5  is changed from the maximum inclination angle to the minimum inclination angle, the movable body  13   a  always pushes the swash plate  5  via the first-side secondary acting portion  71   a  and the second-side secondary acting portion  71   b . Thus, in the compressor of the comparison example, the positions at which the first-side secondary acting portion  71   a  and the second-side secondary acting portion  71   b  contact the weight  5   c  are distant from the center of moment of the load acting on the swash plate  5 , and the movable body  13   a  is likely to be influenced by the compression reaction force. In contrast, when the inclination angle of the swash plate  5  is changed from the maximum inclination angle to the minimum inclination angle as shown in  FIG. 14 , the stroke of the movable body  13   a  is a length S 2 . To ensure the stroke of the movable body  13   a , the swash plate arms  5   e ,  5   f  need to be extended along the axis O to widen the space between the lug plate  51  and the swash plate  5 . Also, to ensure the stroke of the movable body  13   a , the cylinder chamber  51   a  needs to be enlarged in the direction of the axis O together with the lug plate  51 , which consequently increases the size of the actuator  13  in the direction of the axis O. 
     In the compressor of the comparison example, the first-side secondary acting portion  71   a  and the second-side secondary acting portion  71   b  respectively contact the first-side secondary receiving portion  61   a  and the second-side secondary receiving portion  61   b , so that the movable body  13   a  pushes the swash plate  5 . 
     In the first cylindrical portion  131  of the movable body  13   a , the first-side primary acting portion  70   a  and the second-side primary acting portion  70   b  are located between the axis O of the drive shaft  3  and the top dead center associated part T. This sufficiently reduces the stroke of the movable body  13   a  required for changing the inclination angle of the swash plate  5  in the first inclination range. 
     Thus, as shown in  FIG. 12 , the stroke of the movable body  13   a  required for changing the inclination angle of the swash plate  5  from the maximum inclination angle to the minimum inclination angle is a length S 1 , which is shorter than the length S 2  of the stroke in the comparison example shown in  FIG. 14 . Thus, the lug plate  51  and the swash plate  5  can be brought closer to each other along the axis O as shown in  FIG. 12 , so that the actuator  13  can be reduced in size in the direction of the axis O. 
     Also, in the second inclination range, in which it is difficult to increase the thrust of the movable body  13   a , the first-side secondary acting portion  71   a  and the second-side secondary acting portion  71   b  respectively contact the first-side secondary receiving portion  61   a  and the second-side secondary receiving portion  61   b  to push the swash plate  5  at positions distant from the center of moment of the load acting on the swash plate  5  and at positions distant from the top dead center associated part T, at which the compression reaction force is great. 
     In the movable body  13   a , the first-side secondary acting portion  71   a  and the second-side secondary acting portion  71   b  are located between the axis O and the bottom dead center associated part U of the swash plate main portion  50 . Thus, when changing the inclination angle of the swash plate  5  within the second inclination range, the influence of the load such as the compression reaction force acting on the movable body  13   a  is further effectively reduced. 
     Thus, even if the load acting on the movable body  13   a  is decreased when the inclination angle is reduced, the inclination angle can be quickly changed in response to changes in the driving state of the vehicle without increasing the thrust of the movable body  13   a , so that a high controllability is achieved. In this case, the pressure receiving area of the movable body  13   a  does not need to be increased. Thus, the size of the movable body  13   a  and that of the actuator  13  can be reduced. 
     Particularly, when the inclination angle of the swash plate  5  is changed to the inclination angle that corresponds to the boundary between the first inclination range and the second inclination range, the contact state is switched between the first contact state and the second contact state. Thus, the first-side primary acting portion  70   a  and the second-side primary acting portion  70   b , the first-side primary receiving portion  60   a  and the second-side primary receiving portion  60   b , the first-side secondary acting portion  71   a  and the second-side secondary acting portion  71   b , and the first-side secondary receiving portion  61   a  and the second-side secondary receiving portion  61   b  do not interfere with each other. Therefore, the above described operations can be effectively performed. 
     Accordingly, the compressor of the embodiment achieves high controllability while reducing the size. 
     The check valve  38  is switched between the open state and the closed state at the boundary between the second inclination range and the first inclination range. Thus, even if the drive shaft  3  is rotating, the check valve  38  in the closed state prevents the refrigerant gas from flowing back from the condenser  101  to the discharge chamber  35  as long as the inclination angle of the swash plate  5  is in the second inclination range, which includes the minimum inclination angle, and the check valve  38  is switched to the OFF state. On the other hand, the check valve  38  in the open state allows refrigerant gas to flow from the discharge chamber  35  to the condenser  101  as long as the inclination angle of the swash plate  5  is in the first inclination range, which includes the maximum inclination angle, and the check valve  38  is switched to the ON state. In this manner, a clutchless compressor is obtained, in which the drive shaft  3  is not disconnected from the power source by an electromagnetic clutch. 
     The movable body  13   a  has the first-side primary acting portion  70   a , the second-side primary acting portion  70   b , the first-side secondary acting portion  71   a , and the second-side secondary acting portion  71   b , but has no other acting portions. The movable body  13   a  is thus easy to manufacture. 
     The first-side primary acting portion  70   a  and the second-side primary acting portion  70   b  are located on opposite sides of the bottom dead center plane D to form a pair, and the first-side secondary acting portion  71   a  and the second-side secondary acting portion  71   b  are located on opposite sides of the bottom dead center plane D to form a pair. In accordance with these, the first-side primary receiving portion  60   a  and the second-side primary receiving portion  60   b  are located on opposite sides of the bottom dead center plane D to form pair, and the first-side secondary receiving portion  61   a  and the second-side secondary receiving portion  61   b  are located on opposite sides of the bottom dead center plane D to form a pair. 
     With this configuration, the swash plate  5  is unlikely to be inclined in direction other than inclination angle changing directions eve if the movable body  13   a  is pushed in the above described manners. This allows the movable body  13   a  to properly change the inclination angle of the swash plate  5 . 
     Since the swash plate main portion  50  of the swash plate  5  has the weight  5   c , the balance of weight of the swash plate  5  is properly adjusted during rotation, allowing the swash plate  5  to rotate properly. Since the weight  5   c  has the first-side secondary receiving portion  61   a  and the second-side secondary receiving portion  61   b , the first-side secondary acting portion  71   a  and the second-side secondary acting portion  71   b  are allowed to properly contact the first-side secondary receiving portion  61   a  and the second-side secondary receiving portion  61   b , while simplifying the shape of the swash plate  5 . 
     Although the invention has been described with reference to the embodiment, the invention is not limited to the embodiment but may be modified within the scope of the invention. 
     For example, in the range in change the inclination angle of the swash plate  5  from the maximum inclination angle to the minimum inclination angle, a range may be defined in which the first-side primary acting portion  70   a  and the second-side primary acting portion  70   b  respectively push the first-side primary receiving portion  60   a  and the second-side primary receiving portion  60   b , and the first-side secondary acting portion  71   a  and the second-side secondary acting portion  71   b  respectively push the first-side secondary receiving portion  61   a  and the second-side secondary receiving portion  61   b.    
     Also, the first cylindrical portion  131  may be formed without the first-side primary acting portion  70   a  or the second-side primary acting portion  70   b . Instead, the first-side primary receiving portion  60   a  and the second-side primary receiving portion  60   b  may have projecting shapes that are contactable with the rear end face  131   a  of the first cylindrical portion  131 . That is, the rear end face  131   a  of the first cylindrical portion  131  may function as a primary acting portion. The movable body  13   a  may be formed without the first-side secondary acting portion  71   a  or the second-side secondary acting portion  71   b . Instead may have an annular secondary acting portion that is contactable with the first-side secondary receiving portion  61   a  and the second-side secondary receiving portion  61   b . These configurations achieve the same advantages as the compressor of the above illustrated embodiment. With this configuration, the movable body  13   a  does not need to have the rotation stopper  134 , which simplifies the manufacture of the movable body  13   a.    
     Further, in addition to the first-side primary acting portion  70   a , the second-side primary acting portion  70   b , the first-side secondary acting portion  71   a , and the second-side secondary acting portion  71   b , the movable body  13   a  may have an additional acting portion, and the swash plate  5  may have receiving portions that corresponds to the above acting portions. 
     The movable body  13   a  may have only one of the first-side primary acting portion  70   a  and the second-side primary acting portion  70   b  and one of the first-side secondary acting portion  71   a  and the second-side secondary acting portion  71   b . In this case, the swash plate  5  is only required to have one of the first-side primary receiving portion  60   a  and the second-side primary receiving portion  60   b  and one of the first-side secondary receiving portion  61   a  and the second-side secondary receiving portion  61   b . This facilitates the manufacture of the movable body  13   a  and the swash plate  5 . 
     Further, the control valve  15   c  may be provided in the high-pressure passage  15   b  of the control mechanism  15 , and the orifice  15   d  may be provided in the low-pressure passage  15   a . In this case, the control valve  15   c  is allowed to adjust the flow rate of high-pressure refrigerant flowing through the high-pressure passage  15   b . This allows the high-pressure in the discharge chamber  35  to promptly increase the pressure in the control pressure chamber  13   b  and to promptly reduce the displacement. Also, the control valve  15   c  may be replaced by a three-way valve connected to the low-pressure passage  15   a  and the high-pressure passage  15   b . In this case, the opening degree of the three-way valve is adjusted to regulate the flow rate of refrigerant flowing through the low-pressure passage  15   a  and the high-pressure passage  15   b.