Patent Publication Number: US-2016222952-A1

Title: Variable displacement swash plate type compressor

Description:
TECHNICAL FIELD 
     The present invention relates to a variable displacement swash plate type compressor. 
     BACKGROUND ART 
     Patent Literature 1 discloses a conventional variable displacement swash plate type compressor (hereinafter referred to as a compressor). This compressor comprises a housing, a drive shaft, a swash plate, a link mechanism, a plurality of pistons, a conversion mechanism, and a capacity control mechanism. 
     In the housing, a suction chamber, a discharge chamber, a swash plate chamber and a plurality of cylinder bores are formed. The drive shaft is rotatably supported by the housing. The swash plate is rotatable in the swash plate chamber by rotation of the drive shaft. The link mechanism is provided between the drive shaft and the swash plate and permits change of an inclination angle of the swash plate with respect to a direction perpendicular to a driving axis of the drive shaft. The link mechanism has a lug member and a transmission member. The lug member is fixed to the drive shaft in the swash plate chamber. The transmission member is provided integrally with the swash plate in the swash plate chamber, and transmits rotation of the lug member to the swash plate. The pistons are reciprocally accommodated in respective cylinder bores. The conversion mechanism reciprocates the pistons in the cylinder bores at a stroke corresponding to the inclination angle by rotation of the swash plate. The capacity control mechanism has a supply passage, a bleed passage and a control valve. The supply passage provides communication between the discharge chamber and the swash plate chamber. The bleed passage provides communication between the swash plate chamber and the suction chamber. The control valve is capable of changing the pressure in the swash plate chamber by regulating an opening degree of the supply passage. 
     In the compressor, when the control valve increases the pressure in the swash plate chamber, the inclination angle becomes small and the stroke of the pistons decreases. Therefore, a compression capacity per rotation of the drive shaft becomes small. On the other hand, when the control valve decreases the pressure in the swash plate chamber, the inclination angle of the swash plate becomes large, and the stroke of the pistons increases. Therefore, the compression capacity per rotation of the drive shaft becomes large. In this manner, in this compressor, the discharge capacity of refrigerant is changeable in response to the driving conditions of a vehicle or the like on which the compressor is mounted. 
     However, in the case of changing the inclination angle by changing the pressure in the swash plate chamber like this compressor, it is necessary to provide a sufficient amount of refrigerant in the swash plate chamber in order to change the inclination angle. Therefore, the size of the compressor tends to be increased due to a large swash plate chamber. 
     Furthermore, in this compressor, it is inevitable that blow-by gas having a high pressure flows into the swash plate chamber. Furthermore, in this compressor, when the outside air temperature drops, the refrigerant in the swash plate chamber is likely to condense and liquid accumulation occurs in the swash plate chamber. For these reasons, in this compressor, it is difficult to change the inclination angle suitably. 
     Therefore, a compressor as disclosed in Patent Literature 2 has also been proposed. This compressor includes an actuator that is capable of changing an inclination angle, and a control mechanism that controls the actuator. 
     Specifically, the actuator has a lug member, a movable body that engages with a swash plate so as to be rotatable integrally therewith and is movable in the direction of a driving axis to change the inclination angle, and a control pressure chamber that is defined by the lug member and the movable body and moves the movable body by its internal pressure. The control mechanism has a control passage and a control valve. The control passage has a variable pressure passage that communicates with the control pressure chamber, a low pressure passage that communicates with a suction chamber and a swash plate chamber, and a high pressure passage that communicates with a discharge chamber. A part of the variable pressure passage is formed in a drive shaft. The control valve regulates an opening degree of the variable pressure passage, the low pressure passage and the high pressure passage. In other words, the control valve allows the variable pressure passage to communicate with the low pressure passage or the high pressure passage. 
     In this compressor, when the control valve allows the variable pressure passage to communicate with the high pressure passage, the pressure in the control pressure chamber becomes higher than that of the swash plate chamber. Thereby, the movable body of the actuator moves away from the lug member, and the inclination angle decreases. Therefore, the stroke of the pistons decreases and the discharge capacity becomes small. On the other hand, when the control valve allows the variable pressure passage to communicate with the low pressure passage, the pressure in the control pressure chamber becomes as low as that of the swash plate chamber. Thereby, the movable body of the actuator approaches the lug member, and the inclination angle increases. Therefore, the stroke of the pistons increases and the discharge capacity becomes large. 
     Since this compressor is configured to change the pressure in the control pressure chamber, which has a smaller volume than the swash plate chamber, the amount of the refrigerant required to change the inclination angle can be reduced as compared to the compressor configured to change the pressure in the swash plate chamber, and thereby downsizing can be realized. 
     Furthermore, since this compressor is configured to change the inclination angle by changing the pressure in the control pressure chamber, the blow-by gas flowing into the swash plate chamber and the liquid accumulation in the swash plate chamber are less likely to exert an adverse effect on the change of the inclination angle. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Japanese Patent Laid-Open No. 2002-213350 
     Patent Literature 2: Japanese Patent Laid-Open No. 52-131204 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, in the compressor described in Patent Literature 2 described above, a spherical hinge ball, the center of which is disposed on the driving axis, is provided in an insertion hole of the swash plate, and the outer circumferential surface of the hinge ball is slidable with respect to the swash plate. The movable body of the actuator engages with the swash plate via the hinge ball. Therefore, in this compressor, the diameter of the movable body is difficult to increase unless the entire size of the compressor is increased, and it is thus difficult to move the movable body by a larger thrust force. 
     Furthermore, in this compressor, the movable body presses the swash plate via the hinge ball in order to decrease the inclination angle of the swash plate. Here, in this compressor, the position where the outer circumferential surface of the hinge ball contacts with the swash plate is likely to vary due to manufacturing tolerances etc., and for this reason, the direction of the load which acts on the swash plate when the movable body presses the hinge ball is likely to vary. Therefore, in this compressor, it is difficult for the movable body to press the hinge ball in the direction of the driving axis, and it is difficult to stably decrease the inclination angle of the swash plate by the movable body. Furthermore, in this compressor, because the posture of the movable body is unstable, there is a risk that leakage of the pressure from the control pressure chamber occurs. For these reasons, in this compressor, it is difficult to quickly change the discharge capacity in response to the driving conditions of a vehicle or the like, and therefore, sufficient controllability is less likely to be exhibited. 
     The present invention has been made in the light of the conventional circumstances described above, and an object of the invention is to provide a variable displacement swash plate type compressor capable of exhibiting sufficient controllability while realizing downsizing as much as possible. 
     Solution to Problem 
     A variable displacement swash plate type compressor of the present invention comprises: a housing in which a swash plate chamber and a cylinder bore are formed; a drive shaft that is rotatably supported by the housing; a swash plate that is rotatable in the swash plate chamber by rotation of the drive shaft; a link mechanism that is provided between the drive shaft and the swash plate and permits change of an inclination angle of the swash plate with respect to a direction perpendicular to a driving axis of the drive shaft; a piston that is reciprocally accommodated in the cylinder bore; a conversion mechanism that reciprocates the piston in the cylinder bore at a stroke corresponding to the inclination angle by rotation of the swash plate; an actuator capable of changing the inclination angle; and a control mechanism that controls the actuator, wherein the link mechanism has a lug member that is fixed to the drive shaft in the swash plate chamber and a transmission member that transmits rotation of the lug member to the swash plate, an insertion hole that slides on an outer circumference of the drive shaft in accordance with the change of the inclination angle is formed through the swash plate, the swash plate is guided by the link mechanism and the insertion hole in a direction of the driving axis and in a direction of the inclination angle to thereby change the inclination angle, the actuator has the lug member, a movable body that is rotatable integrally with the swash plate and is capable of changing the inclination angle by moving in the direction of the driving axis, and a control pressure chamber that is defined by the lug member and the movable body and moves the movable body by changing its internal pressure by the control mechanism, an acting portion that is capable of pressing the swash plate by the pressure in the control pressure chamber is formed at the movable body, and an acted portion that abuts on and is pressed by the acting portion is formed at the swash plate. 
     In the compressor of the present invention, the transmission member of the link mechanism transmits rotation of the lug member to the swash plate. Subsequently, the acted portion formed at the swash plate abuts on and is pressed by the acting portion formed at the movable body, whereby the inclination angle changes. That is, in this compressor, in order to change the inclination angle, the movable body directly abuts on and presses the swash plate. Because of this, a sleeve such as the hinge ball in the conventional art is not provided between the movable body and the swash plate in this compressor, and therefore, downsizing can be realized by the volume corresponding to such a sleeve. In other words, it is possible to increase the diameter of the movable body so that the movable body moves by a larger thrust force without increasing the size of the entire compressor. 
     Furthermore, in this compressor, since the movable body directly abuts on and presses the swash plate, the direction of the load which acts on the swash plate is less likely to vary. Therefore, in this compressor, the movable body easily presses the swash plate in the direction of the driving axis, and the inclination angle of the swash plate can be stably changed by the movable body. Furthermore, in this compressor, because the posture of the movable body is stable, leakage of the pressure from the control pressure chamber is less likely to occur. For these reasons, in this compressor, it is possible to quickly change the discharge capacity in response to the driving conditions of a vehicle or the like. 
     Accordingly, the compressor of the present invention is capable of exhibiting sufficient controllability while realizing downsizing as much as possible. 
     However, in the swash plate type compressor like this, due to a compression reaction force etc. at the time of operation, a moment to rotate in the direction perpendicular to the driving axis acts on the swash plate. In this regard, in this compressor, the insertion hole formed through the swash plate slides on the outer circumference of the drive shaft in accordance with the change of the inclination angle. Then, the swash plate is guided by the link mechanism and the insertion hole in the direction of the driving axis and in the direction of the inclination angle to thereby change the inclination angle. Consequently, in this compressor, even if the inclination of the swash plate in the direction perpendicular to the driving axis at the time of operation is not prevented by a sleeve, such inclination can be suitably prevented. Due to the elimination of such a sleeve, it is possible to reduce the number of components and thereby realize reduction in manufacturing cost. 
     It is not impossible to employ such a configuration that, for example, the acting portion is connected to the acted portion with a connection pin etc. However, in this case, there is a risk that the configuration of a connection portion changes the posture of the movable body. In addition, because the number of components increases, the configuration of the compressor is complicated and manufacturing cost increases. In contrast, in the compressor of the present invention, the movable body merely abuts directly on and presses the swash plate to change the inclination angle of the swash plate, and therefore, the posture of the movable body is less likely to change. In addition, in this compressor, it is possible to suppress complication of the configuration, and reduction in manufacturing cost can be realized. 
     The control mechanism may have a control passage and a control valve. The control passage may have a variable pressure passage that communicates with the control pressure chamber, a low pressure passage that communicates with a suction chamber or a swash plate chamber, and a high pressure passage that communicates with a discharge chamber. 
     It is preferable that the drive shaft is inserted through the movable body, and the movable body is capable of being fitted to the lug member. In this case, a space for allowing the movable body to move in the direction of the driving axis can be suitably provided between the lug member and the swash plate. 
     Furthermore, the movable body may have a movable cylindrical portion that is formed into a cylindrical shape and coaxial with the driving axis. It is preferable that the lug member has a fixed cylindrical portion that is formed into a cylindrical shape and is coaxial with the driving axis at an outer circumferential side of the movable cylindrical portion to thereby provide the control pressure chamber in the movable cylindrical portion. In this case, by fitting the movable cylindrical portion into the fixed cylindrical portion, the movable body can be fitted to the lug member. Furthermore, since the control pressure chamber is provided in the movable cylindrical portion by the fixed cylindrical portion, the control pressure chamber can be suitably formed between the lug member and the movable body. 
     Furthermore, in this case, a first seal member that seals the control pressure chamber may be provided between the movable cylindrical portion and the drive shaft. In addition, it is preferable that a second seal member that seals the control pressure chamber is provided between the movable cylindrical portion and the fixed cylindrical portion. Thereby, hermeticity of the control pressure chamber can be suitably ensured. Here, as the first seal member and the second seal member, various seals can be employed besides O-rings etc. The first seal member and the second seal member may be of the same kind or different kinds. 
     A thrust bearing that receives a thrust force which acts on the piston may be provided between the housing and the lug member. In addition, it is preferable that the movable cylindrical portion is smaller in diameter than the thrust bearing and capable of advancing to an inner side of the thrust bearing. 
     In this case, it is possible for the thrust bearing to suitably receive a suction reaction force which acts on the piston during a suction phase and a compression reaction force which acts on the piston during a compression phase. Furthermore, by allowing the movable cylindrical portion to advance to the inner side of the thrust bearing, even if the axial length of the compressor is short, the space for allowing the movable body to move in the direction of the driving axis can be sufficiently ensured. 
     In the compressor of the present invention, the position in the movable body where the acting portion is formed and the position in the swash plate where the acted portion is formed can be designed as appropriate. In particular, a top-dead-center corresponding portion for positioning the piston at its top dead center may be defined in the swash plate. In addition, it is preferable that the acting portion and the acted portion are located eccentrically toward the top-dead-center corresponding portion from the driving axis. In this case, the stroke of the movable body in the direction of the driving axis can be reduced as compared with the case where, for example, the acting portion abuts on the acted portion so that the acted portion is pressed by the acting portion on the driving axis, provided that the range of their inclination angle is the same. Therefore, it is possible to suppress enlargement of the compressor in the axial length, and mountability on a vehicle etc. can be improved. 
     In the compressor of the present invention, the acting portion and the acted portion may come into point-contact or line-contact with each other at the operative position. It is preferable that the operative position moves toward the driving axis as the inclination angle decreases. In this case, it is possible to reduce the load exerted on the movable body when the inclination angle decreases. Consequently, in this compressor, controllability can be more enhanced. Here, a straight line on which the operative position and the acted portion are brought into line-contact is perpendicular to a first imaginary plane determined by the top-dead-center corresponding portion of the swash plate and the driving axis. Furthermore, when bringing the acting portion into point-contact or line-contact with the acted portion at the operative position, it is preferable that either one of a portion in the acting portion where it abuts on the acted portion and a portion in the acted portion where it abuts on the acting portion is formed into a curved shape. 
     The acting portion may have an acting surface that extends in the direction perpendicular to the driving axis. It is preferable that the acted portion has a protrusion that protrudes from the swash plate and abuts on the acting surface. In this case, the acting portion and the acted portion can be suitably brought into point-contact or line-contact with each other. 
     It is preferable that the acting portion protrudes from the movable cylindrical portion toward the top-dead-center corresponding portion. In this case, the acting portion easily abuts on the acted portion. 
     It is preferable that the swash plate has a swash plate main body that is formed with the insertion hole and the acted portion that is integrally formed with the swash plate main body. In this case, it is possible to reduce the number of components in the compressor, facilitate manufacturing, and reduce manufacturing cost. 
     It is also preferable that the swash plate has a swash plate main body that is formed with the insertion hole and the acted portion that is fixed to the swash plate main body. In this case, it is possible to improve the flexibility of design with respect to the swash plate main body and the acted portion. 
     In the compressor of the present invention, a suction chamber and a discharge chamber may be formed in the housing. It is preferable that the suction chamber and the swash plate chamber communicate with each other. In this case, the pressure in the swash plate chamber can be made low as well as the suction chamber. 
     Furthermore, the control mechanism may have a control passage that provides communication between the control pressure chamber and the suction chamber and/or the discharge chamber, and a control valve that is capable of regulating an opening degree of the control passage. It is preferable that at least a part of the control passage is formed in the drive shaft. In this case, it is possible to suitably change the pressure in the control pressure chamber and suitably move the movable body while downsizing the control mechanism. 
     A pressure regulation chamber that communicates with the control pressure chamber through the control passage and allows a pressure therein to be changed by the control valve may be formed between the housing and one end of the drive shaft. It is preferable that a third seal member that seals the pressure regulation chamber is provided between the housing and the drive shaft. 
     In this case, when the pressure in the pressure regulation chamber is changed by the control valve, the control pressure chamber moves the movable body. By the third seal member, hermeticity of the pressure regulation chamber can be suitably ensured. Here, as the third seal member, various seals can be employed besides O-rings etc. as in the case of the first and second seal members described above. Furthermore, the third seal member may be of the same kind as or a different kind from the first and second seal members. 
     Advantageous Effects of Invention 
     The compressor of the present invention is capable of exhibiting sufficient controllability while realizing downsizing as much as possible. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a sectional view of a compressor according to Embodiment 1 at the time of maximum displacement. 
         FIG. 2  is a schematic diagram showing a control mechanism of the compressor according to Embodiment 1. 
         FIG. 3  is an enlarged sectional view of an essential part of the compressor according to Embodiment 1, showing a rear end portion of a drive shaft. 
         FIG. 4  is an enlarged sectional view of an essential part of the compressor according to Embodiment 1, showing an actuator. 
         FIG. 5  is a front perspective view showing a swash plate of the compressor according to Embodiment 1. 
         FIG. 6  is a schematic front view showing the swash plate of the compressor according to Embodiment 1. 
         FIG. 7  is a sectional view of the compressor according to Embodiment 1 at the time of minimum displacement. 
         FIG. 8A  is an enlarged sectional view of an essential part of the compressor according to Embodiment 1, showing an operative position where an acting portion abuts on an acted portion when an inclination angle of the swash plate is maximum. 
         FIG. 8B  is an enlarged sectional view of an essential part of the compressor according to Embodiment 1, showing the operative position when the inclination angle is minimum. 
         FIG. 9  is a schematic view of the compressor according to Embodiment 1 and a compressor of a comparative example, showing a difference in strokes of movable bodies. 
         FIG. 10  is a graph showing a relation of the inclination angle and a variable differential pressure. 
         FIG. 11  is a sectional view of a compressor according to Embodiment 2 at the time of maximum displacement. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, Embodiments 1 and 2, which embody the present invention, will be described with reference to the drawings. The compressors of Embodiments 1 and 2 are variable displacement single-head swash plate type compressors. These compressors are both mounted on vehicles and constitute refrigeration circuits of vehicle air-conditioning apparatus. 
     Embodiment 1 
     As shown in  FIG. 1 , the compressor of Embodiment 1 includes a housing  1 , a drive shaft  3 , a swash plate  5 , a link mechanism  7 , a plurality of pistons  9 , a plurality of pairs of shoes  11   a  and  11   b,  an actuator  13 , and a control mechanism  15 , which is shown in  FIG. 2 . In  FIG. 1 , the illustration of the swash plate  5  is partially simplified for ease of explanation. The same applies to  FIGS. 7 and 10 , which will be described later. 
     As shown in  FIG. 1 , the housing  1  has a front housing  17  that is located at a front side in the compressor, a rear housing  19  that is located at a rear side in the compressor, a cylinder block  21  that is located between the front housing  17  and the rear housing  19 , and a valve unit  23 . 
     The front housing  17  has a front wall  17   a  that extends in the up-down direction of the compressor at the front side, and a circumferential wall  17   b  that is integrated with the front wall  17   a  and extends rearward from the front side of the compressor. By the front wall  17   a  and the circumferential wall  17   b,  the front housing  17  is formed into a substantially cylindrical shape with a bottom. Furthermore, by the front wall  17   a  and the circumferential wall  17   b,  a swash plate chamber  25  is formed in the front housing  17 . 
     A boss  17   c  that protrudes frontward is formed on the front wall  17   a.  A shaft seal device  27  is provided in the boss  17   c.  Furthermore, a first shaft hole  17   d  that extends in the front-rear direction of the compressor is formed in the boss  17   c.  A first sliding bearing  29   a  is provided in the first shaft hole  17   d.    
     An inlet port  250  that communicates with the swash plate chamber  25  is formed through the circumferential wall  17   b.  Through the inlet port  250 , the swash plate chamber  25  is connected to an evaporator, which is not illustrated. 
     A part of the control mechanism  15  is provided in the rear housing  19 . In addition, a first pressure regulation chamber  31   a,  a suction chamber  33  and a discharge chamber  35  are formed in the rear housing  19 . The first pressure regulation chamber  31   a  is disposed at the center of the rear housing  19 . The discharge chamber  35  is disposed annularly at an outer circumferential side in the rear housing  19 . Furthermore, the suction chamber  33  is formed annularly between the first pressure regulation chamber  31   a  and the discharge chamber  35  in the rear housing  19 . The discharge chamber  35  is connected to an outlet port, which is not illustrated. 
     Cylinder bores  21   a,  the number of which is the same as that of the pistons  9 , are formed in the cylinder block  21  at equiangular intervals in a circumferential direction. Front end sides of the respective cylinder bores  21   a  communicate with the swash plate chamber  25 . Furthermore, a retainer groove  21   b  that restricts a lift amount of suction reed valves  41   a,  which will be described later, is formed in the cylinder block  21 . 
     Furthermore, a second shaft hole  21   c  that extends in the front-rear direction of the compressor and communicates with the swash plate chamber  25  is formed through the cylinder block  21 . A second sliding bearing  29   b  is provided in the second shaft hole  21   c.  Furthermore, a spring chamber  21   d  is formed in the cylinder block  21 . The spring chamber  21   d  is located between the swash plate chamber  25  and the second shaft hole  21   c.  A return spring  37  is disposed in the spring chamber  21   d.  The return spring  37  urges the swash plate  5  frontward in the swash plate chamber  25  when the inclination angle becomes minimum. Furthermore, a suction passage  39  that communicates with the swash plate chamber  25  is formed in the cylinder block  21 . 
     The valve unit  23  is provided between the rear housing  19  and the cylinder block  21 . The valve unit  23  includes a valve plate  40 , a suction valve plate  41 , a discharge valve plate  43  and a retainer plate  45 . 
     Suction ports  40   a,  the number of which is the same as that of the cylinder bores  21   a,  are formed in the valve plate  40 , the discharge valve plate  43  and the retainer plate  45 . Furthermore, discharge ports  40   b,  the number of which is the same as that of the cylinder bores  21   a,  are formed in the valve plate  40  and the suction valve plate  41 . The respective cylinder bores  21   a  communicate with the suction chamber  33  through the respective suction ports  40   a,  and communicate with the discharge chamber  35  through the respective discharge ports  40   b.  Furthermore, a first communication hole  40   c  and a second communication hole  40   d  are formed in the valve plate  40 , the suction valve plate  41 , the discharge valve plate  43  and the retainer plate  45 . Through the first communication hole  40   c,  the suction chamber  33  and the suction passage  39  communicate with each other. 
     The suction valve plate  41  is provided on the front surface of the valve plate  40 . A plurality of suction reed valves  41   a  that are capable of opening and closing the respective suction ports  40   a  by elastic deformation are formed in the suction valve plate  41 . Furthermore, the discharge valve plate  43  is provided on the rear surface of the valve plate  40 . A plurality of discharge reed valves  43   a  that are capable of opening and closing the respective discharge ports  40   b  by elastic deformation are formed in the discharge valve plate  43 . The retainer plate  45  is provided on the rear surface of the discharge valve plate  43 . The retainer plate  45  restricts a lift amount of the discharge reed valves  43   a.    
     The drive shaft  3  has an outer circumferential surface  30  that is formed into a cylindrical shape. The drive shaft  3  is inserted from the boss  17   c  to the rear side of the housing  1 . The front end side of the drive shaft  3  is supported by the shaft seal device  27  in the boss  17   c  and supported by the first sliding bearing  29   a  in the first shaft hole  17   d.  The rear end side of the drive shaft  3  is supported by the second sliding bearing  29   b  in the second shaft hole  21   c.  In this manner, the drive shaft  3  is rotatably supported around a driving axis O with respect to the housing  1 . A second pressure regulation chamber  31   b  is defined by the rear end of the drive shaft  3  in the second shaft hole  21   c.  The second pressure regulation chamber  31   b  communicates with the first pressure regulation chamber  31   a  through the second communication hole  40   d.  A pressure regulation chamber  31  is formed by the first and the second pressure regulation chambers  31   a  and  31   b.    
     As shown in  FIG. 3 , ring grooves  3   c  and  3   d  are formed at the rear end of the drive shaft  3 . O-rings  49   a  and  49   b  are provided in the ring grooves  3   c  and  3   d,  respectively. The pressure regulation chamber  31  is sealed with the O-rings  49   a  and  49   b,  whereby the swash plate chamber  25  does not communicate with the pressure regulation chamber  31 . The O-rings  49   a  and  49   b  correspond to the third seal member in the present invention. 
     As shown in  FIG. 1 , the link mechanism  7 , the swash plate  5  and the actuator  13  are attached to the drive shaft  3 . The link mechanism  7  includes a lug plate  51 , a pair of lug arms  53  that are formed at the lug plate  51 , and a pair of swash plate arms  5   e  and  5   f .  The lug plate  51  corresponds to the lug member in the present invention. Furthermore, the swash plate arms  5   e  and  5   f  correspond to the transmission member in the present invention. 
     The lug plate  51  is formed into a substantially annular shape. The lug plate  51  is press-fitted to the drive shaft  3  and rotatable integrally with the drive shaft  3 . The lug plate  51  is located at the front end side in the swash plate chamber  25  and disposed in front of the swash plate  5 . Furthermore, a thrust bearing  55  is provided between the lug plate  51  and the front wall  17   a.    
     As shown in  FIG. 4 , a fixed cylindrical portion  51   a  that is formed into a cylindrical shape and extends in the front-rear direction of the lug plate  51  is provided in a recessed manner in the lug plate  51 . As shown in  FIG. 1 , the fixed cylindrical portion  51   a  extends from the rear end surface of the lug plate  51  to a position on an inner side of the thrust bearing  55  in the lug plate  51 . 
     The lug arms  53  extend rearward from the lug plate  51 . Furthermore, a cam surface  51   b  is formed at the lug plate  51  at a position between the lug arms  53 . In  FIG. 1  etc., only one of the lug arms  53  is illustrated for ease of explanation. 
     As shown in  FIG. 5 , the swash plate  5  has a swash plate main body  50 , the swash plate arms  5   e  and  5   f,  and a protrusion  5   g.  The protrusion  5   g  corresponds to the acted portion in the present invention. 
     The swash plate main body  50  is formed into an annular flat-plate shape and has a front surface  5   a  and a rear surface  5   b;  in addition, a top-dead-center corresponding portion T for positioning the respective pistons  9  at their top dead center is defined therein. A restriction portion  5   c  that protrudes frontward from the swash plate  5  is formed on the front surface  5   a.  As shown in  FIG. 1 , the restriction portion  5   c  abuts on the lug plate  51  when the inclination angle of the swash plate  5  becomes maximum. Furthermore, the swash plate main body  50  is formed with an insertion hole  5   d.  The drive shaft  3  is inserted through the insertion hole  5   d.    
     As shown in  FIG. 6 , a pair of guide surfaces  52   a  and  52   b  having a flat-plate shape is formed in the insertion hole  5   d.  The guide surfaces  52   a  and  52   b  abut on the outer circumferential surface  30  of the drive shaft  3  when the drive shaft  3  has been inserted through the insertion hole  5   d.  In  FIG. 6 , illustration of the swash plate arms  5   e  and  5   f,  the protrusion  5   g  etc. is simplified for ease of explanation. 
     As shown in  FIG. 5 , the swash plate arms  5   e  and  5   f  are formed on the front surface  5   a  of the swash plate main body  50  at positions eccentric toward the top-dead-center corresponding portion T of the swash plate  5  from the driving axis O. The swash plate arms  5   e  and  5   f  extend frontward from the front surface  5   a.    
     The protrusion  5   g  protrudes frontward from the front surface  5   a  and is integrated with the swash plate main body  50 . The protrusion  5   g  is formed into a substantially hemispherical shape, and located eccentrically toward the top-dead-center corresponding portion T of the swash plate  5  from the driving axis O so as to be disposed between the swash plate arm  5   e  and the swash plate arm  5   f.    
     As shown in  FIG. 1 , by inserting the swash plate arms  5   e  and  5   f  between the lug arms  53 , the lug plate  51  is connected to the swash plate  5 . Thereby, the swash plate  5  is rotatable along with the lug plate  51  in the swash plate chamber  25 . The tip ends of the swash plate arms  5   e  and  5   f  abut on the cam surface  51   b.    
     By connecting the lug plate  51  to the swash plate  5 , the swash plate arms  5   e  and  5   f  and the protrusion  5   g  are located eccentrically toward the top-dead-center corresponding portion T of the swash plate  5  from the driving axis O. In addition, the swash plate arms  5   e  and  5   f  slide on the cam surface  51   b,  whereby the swash plate  5  is able to change its inclination angle with respect to the direction perpendicular to the driving axis O from the maximum inclination angle shown in  FIG. 1  to the minimum inclination angle shown in  FIG. 7  while substantially maintaining the position of the top-dead-center corresponding portion T. At this time, in accordance with the change of the inclination angle of the swash plate  5 , the guide surfaces  52   a  and  52   b  shown in  FIG. 6  slide on the outer circumferential surface  30  of the drive shaft  3 . In this manner, the swash plate  5  is guided by the link mechanism  7  and the drive shaft  3  in the direction of the driving axis O and in the direction of the inclination angle, whereby the inclination angle changes as described above. 
     As shown in  FIG. 4 , the actuator  13  includes the lug plate  51 , a movable body  13   a  and a control pressure chamber  13   b.    
     The movable body  13   a,  through which the drive shaft  3  is inserted, is slidable in contact with the drive shaft  3  to move in the direction of the driving axis O. The movable body  13   a  is formed into a cylindrical shape and coaxial with the drive shaft  3 , and the diameter thereof is smaller than that of the thrust bearing  55  shown in  FIG. 1 . As shown in  FIG. 4 , the movable body  13   a  has a first movable cylindrical portion  131 , a second movable cylindrical portion  132  and a third movable cylindrical portion  133 . The first movable cylindrical portion  131  is located at a rear end side in the movable body  13   a  and has the smallest diameter in the movable body  13   a.  The second movable cylindrical portion  132  continues from the front end of the first movable cylindrical portion  131  and is formed such that its diameter increases gradually toward the front side of the movable body  13   a.  The third movable cylindrical portion  133  continues from the front end of the second movable cylindrical portion  132  and extends toward the front side of the movable body  13   a.  The third movable cylindrical portion  133  has the largest diameter in the movable body  13   a.    
     Furthermore, an acting portion  134  is integrally formed at the rear end of the first movable cylindrical portion  131 . As shown in  FIG. 1 , the acting portion  134  extends vertically from a position near the driving axis O toward the top-dead-center corresponding portion T of the swash plate  5 , and is located eccentrically toward the top-dead-center corresponding portion T of the swash plate  5  from the driving axis O. The acting portion  134  has an acting surface  134   a  which is formed into a flat shape. As shown in  FIG. 8 , the acting surface  134   a  comes into point-contact with the protrusion  5   g  at an operative position F. Thereby, the movable body  13   a  is rotatable integrally with the lug plate  51  and the swash plate  5 . Here, since the protrusion  5   g  and the acting portion  134  are located eccentrically toward the top-dead-center corresponding portion T of the swash plate  5  from the driving axis O, the operative position F is also located eccentrically toward the top-dead-center corresponding portion T of the swash plate  5  from the driving axis O as shown in  FIG. 1 . 
     The movable body  13   a  is capable of being fitted to the lug plate  51  by allowing the second movable cylindrical portion  132  and the third movable cylindrical portion  133  shown in  FIG. 4  to advance into the fixed cylindrical portion  51   a  (see  FIG. 1 ). When the second movable cylindrical portion  132  and the third movable cylindrical portion  133  has advanced farthest into the fixed cylindrical portion  51   a,  the third movable cylindrical portion  133  reaches a position on an inner side of the thrust bearing  55  in the fixed cylindrical portion  51   a.    
     As shown in  FIG. 4 , the control pressure chamber  13   b  is formed by the second movable cylindrical portion  132 , the third movable cylindrical portion  133 , the fixed cylindrical portion  51   a  and the drive shaft  3 . Furthermore, a ring groove  131   a  is formed in the inner circumferential surface of the first movable cylindrical portion  131 , and a ring groove  133   a  is formed in the outer circumferential surface of the third movable cylindrical portion  133 . O-rings  49   c  and  49   d  are provided in the ring grooves  131   a  and  133   a,  respectively. The O-ring  49   c  corresponds to the first seal member in the present invention, and the O-ring  49   d  corresponds to the second seal member in the present invention. The control pressure chamber  13   b  is sealed with the O-rings  49   c  and  49   d,  whereby the hermeticity of the control pressure chamber  13   b  is ensured. 
     As shown in  FIG. 1 , an axial path  3   a  that extends in the direction of the driving axis O from the rear end of the drive shaft  3  toward the front end thereof and a radial path  3   b  that extends radially from the front end of the axial path  3   a  and opens at the outer circumferential surface  30  of the drive shaft  3  are formed in the drive shaft  3 . The rear end of the axial path  3   a  opens to the pressure regulation chamber  31 . The radial path  3   b  opens to the control pressure chamber  13   b.  Through the axial path  3   a  and the radial path  3   b,  the pressure regulation chamber  31  and the control pressure chamber  13   b  communicate with each other. 
     The drive shaft  3  is connected to a pulley or an electromagnetic clutch, which are not illustrated, via a screw portion  3   e  which is formed at the tip end thereof. 
     The pistons  9  are respectively accommodated in the respective cylinder bores  21   a  and capable of reciprocating in the respective cylinder bores  21   a.  Compression chambers  57  are defined in the respective cylinder bores  21   a  by the respective pistons  9  and the valve unit  23 . 
     Furthermore, an engaging portion  9   a  is formed in a recessed manner in each of the pistons  9 . The shoes  11   a  and  11   b  formed into a hemispherical shape are provided in the respective engaging portions  9   a.  The shoes  11   a  and  11   b  convert the rotation of the swash plate  5  into reciprocal movement of the pistons  9 . The shoes  11   a  and  11   b  correspond to the conversion mechanism in the present invention. In this manner, the pistons  9  are able to reciprocate in the cylinder bores  21   a  at a stroke corresponding to the inclination angle of the swash plate  5 . Alternatively, instead of the shoes  11   a  and  11   b,  it is also possible to employ a wobble type conversion mechanism, in which a wobble plate is supported at the side of the rear surface  5   b  of the swash plate main body  50  via a thrust bearing and the wobble plate is connected to the respective pistons  9  via connecting rods. 
     As shown in  FIG. 2 , the control mechanism  15  has a low pressure passage  15   a,  a high pressure passage  15   b,  a control valve  15   c,  an orifice  15   d,  the axial path  3   a  and the radial path  3   b.  A control passage in the present invention is formed by the low pressure passage  15   a,  the high pressure passage  15   b,  the axial path  3   a  and the radial path  3   b.  Furthermore, the axial path  3   a  and the radial path  3   b  serve as variable pressure passages. 
     The low pressure passage  15   a  is connected to the pressure regulation chamber  31  and the suction chamber  33 . Thereby, the control pressure chamber  13   b,  the pressure regulation chamber  31  and the suction chamber  33  communicate with one another through the low pressure passage  15   a,  the axial path  3   a  and the radial path  3   b.  The high pressure passage  15   b  is connected to the pressure regulation chamber  31  and the discharge chamber  35 . The control pressure chamber  13   b,  the pressure regulation chamber  31  and the discharge chamber  35  communicate with one another through the high pressure passage  15   b,  the axial path  3   a  and the radial path  3   b.  Furthermore, the high pressure passage  15   b  is provided with the orifice  15   d,  whereby the flow rate of the refrigerant flowing through the high pressure passage  15   b  is reduced. 
     The control valve  15   c  is provided at the low pressure passage  15   a.  The control valve  15   c  is capable of regulating the flow rate of the refrigerant flowing through the low pressure passage  15   a  based on the pressure in the suction chamber  33 . 
     In this compressor, a pipe that leads to the evaporator is connected to the inlet port  250  shown in  FIG. 1 , and a pipe that leads to a condenser is connected to the outlet port. The condenser is connected to the evaporator via pipes and an expansion valve. The refrigeration circuit of vehicle air-conditioning apparatus is constituted by the compressor, the evaporator, the expansion valve, the condenser and the like. Illustration of the evaporator, the expansion valve, the condenser and the pipes is omitted. 
     In the compressor configured as above, by rotation of the drive shaft  3 , the swash plate  5  rotates and the pistons  9  reciprocate in the respective cylinder bores  21   a.  The volume of the compression chambers  57  thus changes in response to the stroke of the pistons  9 . The refrigerant introduced from the evaporator into the swash plate chamber  25  through the inlet port  250  thus passes the suction chamber  33  through the suction passage  39  and then is compressed in the compression chambers  57 . Subsequently, the refrigerant compressed in the compression chambers  57  is discharged to the discharge chamber  35  and then discharged to the condenser from the outlet port. 
     During this time, in this compressor, a piston compression force that reduces the inclination angle of the swash plate  5  acts on the swash plate  5 , the lug plate  51  and the like. By changing the inclination angle of the swash plate  5  to increase or decrease the stroke of the pistons  9 , it is possible to perform capacity control in this compressor. 
     Specifically, in the control mechanism  15 , when the control valve  15   c  shown in  FIG. 2  increases the flow rate of the refrigerant flowing through the low pressure passage  15   a,  the refrigerant in the discharge chamber  35  is less likely to pass the high pressure passage  15   b  and the orifice  15   d  and be stored in the pressure regulation chamber  31 . Therefore, the pressure in the control pressure chamber  13   b  becomes substantially equal to that in the suction chamber  33 . As a result, as shown in  FIG. 1 , due to the piston compression force acting on the swash plate  5 , in the actuator  13 , the volume of the control pressure chamber  13   b  decreases and the movable body  13   a  moves from the side of the swash plate  5  toward the lug plate  51  in the direction of the driving axis O. Then, in the movable body  13   a,  the second movable cylindrical portion  132  and the third movable cylindrical portion  133  advance into the fixed cylindrical portion  51   a.    
     At the same time, in this compressor, due to the piston compression force and the urging force of the return spring  37  acting on the swash plate  5 , the swash plate arms  5   e  and  5   f  slide on the cam surface  51   b  so as to move away from the driving axis O. Therefore, a bottom dead center side of the swash plate  5  pivots in a clockwise direction while substantially maintaining the position of the top-dead-center corresponding portion T. In this manner, in this compressor, the inclination angle of the swash plate  5  with respect to the direction perpendicular to the driving axis O of the drive shaft  3  increases. Thereby, in this compressor, the stroke of the pistons  9  increases and the discharge capacity per rotation of the drive shaft  3  becomes large. Here, the inclination angle of the swash plate  5  shown in  FIG. 1  is the maximum inclination angle in this compressor. When the swash plate  5  is at the maximum inclination angle, the swash plate arms  5   e  and  5   f  abut on the cam surface  51   b  at a first position P 1 . 
     On the other hand, when the control valve  15   c  shown in  FIG. 2  decreases the flow rate of the refrigerant flowing through the low pressure passage  15   a,  the refrigerant in the discharge chamber  35  is more likely to pass the high pressure passage  15   b  and the orifice  15   d  and be stored in the pressure regulation chamber  31 . Therefore, the pressure in the control pressure chamber  13   b  becomes substantially equal to that of the discharge chamber  35 , and the pressure in the control pressure chamber  13   b  becomes higher than that of the swash plate chamber  25 . As a result, as shown in  FIG. 7 , in the actuator  13 , the volume of the control pressure chamber  13   b  increases and the movable body  13   a  moves away from the lug plate  51  toward the swash plate  5  in the direction of the driving axis O. 
     Thereby, in this compressor, at the operative position F, the acting surface  134   a  of the acting portion  134  presses the protrusion  5   g  rearward in the swash plate chamber  25 . Therefore, the swash plate arms  5   e  and  5   f  slide on the cam surface  51   b  so as to approach the driving axis O, and the bottom dead center side of the swash plate  5  pivots in a counterclockwise direction while substantially maintaining the position of the top-dead-center corresponding portion T. In this manner, in this compressor, the inclination angle of the swash plate  5  with respect to the direction perpendicular to the driving axis O of the drive shaft  3  decreases. Thereby, in this compressor, the stroke of the pistons  9  decreases and the discharge capacity per rotation of the drive shaft  3  becomes small. Furthermore, when the inclination angle decreases, the swash plate  5  abuts on the return spring  37 . Here, the inclination angle of the swash plate  5  shown in  FIG. 7  is the minimum inclination angle in this compressor. When the swash plate  5  is at the minimum inclination angle, the swash plate arms  5   e  and  5   f  abut on the cam surface  51   b  at a second position P 2 . 
     As described above, this compressor employs the actuator  13  so as to change the inclination angle of the swash plate  5  by changing the pressure in the control pressure chamber  13   b,  which has a smaller volume than the swash plate chamber  25 . Therefore, in this compressor, the amount of the refrigerant required to change the inclination angle can be reduced as compared to the compressor configured to change the inclination angle by changing the pressure in the swash plate chamber  25 . As a result, this compressor is capable of suppressing enlargement of the swash plate chamber  25  and the housing  1 . 
     Furthermore, in this compressor, the swash plate arms  5   e  and  5   f  of the link mechanism  7  transmit the rotation of the lug plate  51  to the swash plate  5  and permit change of the inclination angle while substantially maintaining the position of the top-dead-center corresponding portion T of the swash plate  5 . The protrusion  5   g  formed at the swash plate main body  50  abuts on and is pressed by the acting portion  134  formed at the movable body  13   a,  and thereby the inclination angle of the swash plate  5  changes. That is, in this compressor, in order to change the inclination angle of the swash plate  5 , the movable body  13   a  directly abuts on and presses the swash plate  5 . Because of this, a sleeve such as the hinge ball in the conventional art is not provided between the movable body  13   a  and the swash plate  5  in this compressor, and therefore, downsizing can be realized by the volume corresponding to such a sleeve. 
     Furthermore, in this compressor, since the movable body  13   a  directly abuts on and presses the swash plate  5 , the direction of the load which acts on the swash plate  5  is less likely to vary. Consequently, in this compressor, the movable body  13   a  easily presses the swash plate  5  in the direction of the driving axis O, and the movable body  13   a  is able to stably change the inclination angle of the swash plate  5 . Furthermore, in this compressor, because the posture of the movable body  13   a  is stable, leakage of the pressure from the control pressure chamber  13   b  is less likely to occur. 
     In this compressor, the acting portion  134  of the movable body  13   a  and the protrusion  5   g  formed at the swash plate main body are located eccentrically toward the top-dead-center corresponding portion T of the swash plate  5  from the driving axis O. Therefore, in this compressor, a space for allowing the movable body  13   a  to move in the direction of the driving axis O is easily provided between the lug plate  51  and the swash plate  5  without disrupting the change of the inclination angle. Therefore, in this compressor, it is possible to increase the diameter of the actuator  13  and move the movable body  13   a  by a sufficient thrust force. As a result, this compressor is capable of quickly changing the inclination angle in response to the driving conditions of a vehicle. 
     Furthermore, in this compressor, the swash plate arms  5   e  and  5   f  substantially maintains the position of the top-dead-center corresponding portion T and the acting surface  134   a  abuts on the protrusion  5   g,  whereby the movable body  13   a  presses the swash plate  5  at a position near the top-dead-center corresponding portion T. Therefore, in this compressor, the stroke of the movable body  13   a  in the direction of the driving axis O can be reduced as compared to the compressor in which the protrusion  5   g  is not provided, provided that the range of their inclination angle is the same. As a result, enlargement of the compressor in the axial length is suppressed. Specific explanation will be provided below by comparison with a comparative example. 
     The compressor of the comparative example is configured by partially changing the compressor of Embodiment 1 such that the protrusion  5   g  and the acting portion  134  are not provided in the swash plate  5  and the movable body  13   a.  Thereby, in the compressor of the comparative example, the rear end of the first movable cylindrical portion  131  of the movable body  13   a  comes into contact with the front surface  5   a  at a position around the insertion hole  5   d.  Therefore, in the compressor of the comparative example, the movable body  13   a  abuts on the swash plate  5  at a position almost on the driving axis O. 
     In the compressor of the comparative example like this, in order to displace the swash plate  5  at the maximum inclination angle in  FIG. 9  (see the double-dashed chain line) until it reaches the minimum inclination angle, the movable body  13   a  needs to move by a distance S 2  in the direction of the driving axis O. 
     In contrast, in the compressor of Embodiment 1, it is sufficient if the movable body  13   a  moves by a distance S 1  in the direction of the driving axis O in order to displace the swash plate  5  at the maximum inclination angle until it reaches the minimum inclination angle. That is, in the compressor of Embodiment 1, the stroke of the movable body  13   a  in the direction of the driving axis O is shorter than that of the compressor in the comparative example. 
     Furthermore, as shown  FIG. 8A , in the compressor of Embodiment 1, when the inclination angle is maximum, the acting surface  134   a  comes into point-contact with the protrusion  5   g  at the operative position F which is distant from the driving axis O. Then, as the inclination angle decreases, the position where the swash plate arms  5   e  and  5   f  abut on the cam surface  51   b  moves toward the second position P 2 . Thereby, in this compressor, as shown by the white arrow in  FIG. 8B , the operative position F moves toward the driving axis O as the inclination angle decreases. Here, in this compressor, even when the inclination angle becomes minimum, the operative position F does not move to the opposite side of the top-dead-center corresponding portion T across the driving axis O. In contrast, in the compressor of the comparative example, the operative position between the movable body  13   a  and the swash plate  5  is almost unchanged even when the inclination angle changes. 
     Therefore, as the graph in  FIG. 10  shows, in the compressor of Embodiment 1, the load exerted on the movable body  13   a  at the time of decreasing the inclination angle can be reduced. Thereby, in this compressor, the difference in pressure between the swash plate chamber  25  and the control pressure chamber  13   b  (hereinafter referred to as a variable differential pressure) at the time of changing the inclination angle can be made small and almost uniform as a whole. 
     In contrast, in the compressor of the comparative example, since the operative position is almost unchanged, a large load is exerted on the movable body  13   a  when decreasing the inclination angle. Therefore, in the compressor of the comparative example, the variable differential pressure needs to be increased as the inclination angle decreases. 
     Accordingly, the compressor of Embodiment 1 is capable of exhibiting sufficient controllability while realizing downsizing as much as possible. 
     Furthermore, in this compressor, due to the compression reaction force etc. at the time of operation, a moment to rotate in the direction perpendicular to the driving axis O acts on the swash plate  5 . In this regard, in this compressor, the guide surfaces  52   a  and  52   b  formed in the insertion hole  5   d  slide on the outer circumferential surface  30  of the drive shaft  3  in accordance with the change of the inclination angle of the swash plate  5 . Then, the swash plate  5  changes its inclination angle while being guided by the link mechanism  7  and the drive shaft  3  in the direction of the driving axis O and in the direction of the inclination angle. Consequently, in this compressor, even if the inclination of the swash plate  5  in the direction perpendicular to the driving axis O at the time of operation is not prevented by a sleeve, such inclination can be suitably prevented. In this compressor, due to the elimination of such a sleeve, it is possible to reduce the number of components and thereby realize reduction in manufacturing cost. 
     Furthermore, in this compressor, in order to change the inclination angle of the swash plate  5 , the movable body  13   a  merely abuts directly on and presses the swash plate  5 , and the acting portion  134  is not connected to the protrusion  5   g  with a connection pin or the like. Consequently, in this compressor, there is no risk that the configuration of a connecting portion changes the posture of the movable body  13   a,  and thus, the posture of the movable body  13   a  is less likely to change at the time of changing the inclination angle. Furthermore, in this compressor, it is possible to suppress complication of the configuration and realize reduction in manufacturing cost also in this aspect. 
     Furthermore, in this compressor, the drive shaft  3  is inserted through the movable body  13   a,  and the movable body  13   a  is capable of being fitted to the lug plate  51  by accommodating the movable body  13   a  in the fixed cylindrical portion  51   a.  Here, in this compressor, the third movable cylindrical portion  133  of the movable body  13   a  advances to the position on the inner side of the thrust bearing  55  in the fixed cylindrical portion  51   a.  Therefore, in this compressor, the space for allowing the movable body  13   a  to move in the direction of the driving axis O can be suitably provided between the lug plate  51  and the swash plate  5  while making the axial length short. Furthermore, the thrust bearing  55  provided in the compressor can suitably receive the suction reaction force and the compression reaction force which act on the pistons  9 . 
     Furthermore, in this compressor, the control pressure chamber  13   b  can be suitably formed between the lug plate  51  and the movable body  13   a  by the fixed cylindrical portion  51   a.  In this compressor, the hermeticity of the control pressure chamber  13   b  is suitably ensured by the O-rings  49   c  and  49   d  which are provided at the first and the third movable cylindrical portions  131  and  133  respectively. 
     In this compressor, the acting portion  134  protrudes from the first movable cylindrical portion  131  toward the top-dead-center corresponding portion T of the swash plate  5  and is integrated with the movable body  13   a.  Furthermore, the acting surface  134   a  is formed at the acting portion  134 . Thereby, in this compressor, the acting surface  134   a  can easily abut on the protrusion  5   g  at the position eccentric toward the top-dead-center corresponding portion T from the driving axis O. Here, since the protrusion  5   g  is formed to protrude in a substantially hemispherical manner, the acting surface  134   a  can be suitably brought into point-contact with the protrusion  5   g,  and thereby the swash plate  5  can easily change its inclination angle. 
     Furthermore, the protrusion  5   g  is integrally formed with the front surface  5   a  of the swash plate main body  50 . Therefore, in this compressor, it is possible to reduce the number of components, facilitate manufacturing, and reduce manufacturing cost. 
     Furthermore, in this compressor, the swash plate chamber  25  and the suction chamber  33  communicate with each other through the suction passage  39 . Thereby, in this compressor, the pressure in the swash plate chamber  25  can be made low as well as the suction chamber  33 . 
     Furthermore, the control mechanism  15  adjusts the pressure in the pressure regulation chamber  31  and thus the pressure in the control pressure chamber  13   b  by regulating the opening degree of the control valve  15   c.  In addition, the axial path  3   a  and the radial path  3   b  are formed in the drive shaft  3 . Consequently, in this compressor, it is possible to suitably change the pressure in the control pressure chamber  13   b  and suitably move the movable body  13   a  while downsizing the control mechanism  15 . 
     Furthermore, in this compressor, the hermeticity of the pressure regulation chamber  31  is suitably ensured by the O-rings  49   a  and  49   b  which are provided at the rear end of the drive shaft  3 . 
     Embodiment 2 
     As shown in  FIG. 11 , in a compressor of Embodiment 2, the swash plate  5  has the swash plate main body  50 , the swash plate arms  5   e  and  5   f  and a contact member  59 . The contact member  59  also corresponds to the acted portion in the present invention. 
     The contact member  59  is formed to be a separate body from the swash plate main body  50 . The contact member  59  is attached to the front surface  5   a  of the swash plate main body  50  at a position between the swash plate arms  5   e  and  5   f,  and located eccentrically toward the top-dead-center corresponding portion T of the swash plate  5  from the driving axis O. 
     A protrusion  59   a  that protrudes frontward is formed at the contact member  59 . The protrusion  59   a  is formed into a substantially hemispherical shape. The protrusion  59   a  comes into point-contact with the acting surface  134   a  of the acting portion  134  at the operative position F. In this manner, in this compressor, via the acting surface  134   a  and the protrusion  59   a,  the acting portion  134  abuts on the contact member  59  at a position eccentric toward the top-dead-center corresponding portion T of the swash plate  5  from the driving axis O. The other components of this compressor are the same as those of the compressor of Embodiment 1, and, where the components are the same, same reference numerals are used and detailed explanation thereof is omitted. 
     In this compressor, since the swash plate  5  and the contact member  59  are separate bodies, it is possible to improve the flexibility of design with respect to the swash plate main body  50  and the contact member  59 . The other operations of this compressor are the same as those of the compressor of Embodiment 1. 
     Although the present invention has been described above in line with Embodiments 1 and 2, it is needless to say that the present invention is not limited to Embodiments 1 and 2 described above and may be modified and applied as appropriate without departing from the gist of the invention. 
     For example, the compressors of Embodiments 1 and 2 may be configured such that the operative position F moves toward the driving axis O while the inclination angle of the swash plate  5  decreases to a predetermined angle from the maximum state, and the operative position F does not move while the inclination angle of the swash plate  5  reaches its minimum inclination angle from the predetermined angle. 
     Furthermore, the protrusion  5   g  and the protrusion  59   a  may be formed into a flat-plate shape, and the acting surface  134   a  of the acting portion  134  may be formed into a curved shape. This enables the protrusion  5   g  and the protrusion  59   a  to come into line-contact with the acting portion  134  at the operative position F. 
     Furthermore, the control mechanism  15  may be configured such that the control valve  15   c  is provided at the high pressure passage  15   b  and the orifice  15   d  is provided at the low pressure passage  15   a.  In this case, the flow rate of the high-pressure refrigerant flowing through the high pressure passage  15   b  can be regulated by the control valve  15   c.  Therefore, due to the high pressure in the discharge chamber  35 , the pressure in the control pressure chamber  13   b  can be increased quickly and the compression capacity can be decreased quickly. Furthermore, instead of the control valve  15   c,  a three-way valve that is connected to the low pressure passage  15   a  and the high pressure passage  15   b  may be provided so that the flow rate of the refrigerant flowing through the low pressure passage  15   a  and the high pressure passage  15   b  is adjusted by regulating an opening degree of the three-way valve. 
     INDUSTRIAL APPLICABILITY 
     The present invention is applicable to air-conditioning apparatus and the like. 
     REFERENCE SIGNS LIST 
     
         
           1  HOUSING 
           3  DRIVE SHAFT 
           3   a  AXIAL PATH (CONTROL PASSAGE) 
           3   b  RADIAL PATH (CONTROL PASSAGE) 
           5  SWASH PLATE 
           5   d  INSERTION HOLE 
           5   e,    5   f  SWASH PLATE ARM (TRANSMISSION MEMBER) 
           5   g  PROTRUSION (ACTED PORTION) 
           7  LINK MECHANISM 
           9  PISTON 
           11   a,    11   b  SHOE (CONVERSION MECHANISM) 
           13  ACTUATOR 
           13   a  MOVABLE BODY 
           13   b  CONTROL PRESSURE CHAMBER (CONTROL PASSAGE) 
           15  CONTROL MECHANISM 
           15   a  LOW PRESSURE PASSAGE (CONTROL PASSAGE) 
           15   b  HIGH PRESSURE PASSAGE (CONTROL PASSAGE) 
           15   c  CONTROL VALVE 
           25  SWASH PLATE CHAMBER 
           30  OUTER CIRCUMFERENTIAL SURFACE 
           31  PRESSURE REGULATION CHAMBER 
           33  SUCTION CHAMBER 
           35  DISCHARGE CHAMBER 
           21   a  CYLINDER BORE 
           49   a,    49   b  O-RING (THIRD SEAL MEMBER) 
           49   c  O-RING (FIRST SEAL MEMBER) 
           49   d  O-RING (SECOND SEAL MEMBER) 
           50  SWASH PLATE MAIN BODY 
           51  LUG PLATE (LUG MEMBER) 
           51   a  FIXED CYLINDRICAL PORTION 
           55  THRUST BEARING 
           59  CONTACT MEMBER (ACTED PORTION) 
           59   a  PROTRUSION 
           131  FIRST MOVABLE CYLINDRICAL PORTION (MOVABLE CYLINDRICAL PORTION) 
           132  SECOND MOVABLE CYLINDRICAL PORTION (MOVABLE CYLINDRICAL PORTION) 
           133  THIRD MOVABLE CYLINDRICAL PORTION (MOVABLE CYLINDRICAL PORTION) 
           134  ACTING PORTION 
         F OPERATIVE POSITION 
         O DRIVING AXIS 
         T TOP-DEAD-CENTER CORRESPONDING PORTION