Patent Publication Number: US-2009220355-A1

Title: Swash plate compressor

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority to Japanese Patent Application No. 2008-25757, filed on Feb. 5, 2008, No. 2008-38686, filed on Feb. 20, 2008, and No. 2008-52548, filed on Mar. 3, 2008, the contents of which are hereby incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a swash plate compressor. 
     JP-A-8-284816 discloses a conventional swash plate compressor. The swash plate compressor includes a housing composed of a front housing, a cylinder block and a rear housing, and the housing defines a plurality of cylinder bores, a suction chamber, a discharge chamber and a crank chamber therein. The front housing rotatably supports a drive shaft, one end of which is exposed from the front housing. In the crank chamber, a swash plate is supported by the drive shaft so as to vary its inclination angle. Pistons are reciprocatingly received in the respective cylinder bores. Pairs of front and rear shoes are provided between the swash plate and the respective pistons for converting wobbling motions of the swash plate into reciprocation of the respective pistons. A supply passage provides communication between the discharge chamber and the crank chamber and a capacity control valve is provided on the supply passage to regulate pressure in the crank chamber. 
     Also, the swash plate compressor is formed with a release passage, which communicates the crank chamber to the suction chamber. With the swash plate compressor disclosed in the aforementioned patent application publication, the release passage includes a first radial hole formed to extend radially of the drive shaft, and an outflow hole which communicates the first radial hole to the suction chamber. A lug plate is fixed to the drive shaft in a manner to rotate together therewith and an oil supply passage is formed on the lug plate to extend toward a center from an outer peripheral region of the crank chamber. Also, a shaft seal device is provided to seal between the front housing and the drive shaft, and a lubrication passage is formed on the front housing to communicate the oil supply passage to the first radial hole at a location where the shaft seal device is provided. 
     The swash plate compressor together with a condenser, an expansion valve, and an evaporator constitutes a refrigerating circuit, and the refrigerating circuit is used air-conditioning apparatus for a vehicle. With the swash plate compressor, the capacity control valve adjusts pressure in the crank chamber on the basis of pressure in the suction chamber or a flow rate of refrigerating gas to change an angle of the swash plate with respect to the drive shaft to thereby change a discharge capacity thereof. 
     Also, with the swash plate compressor, in an outer peripheral region of the crank chamber, lubricating oil is present in abundance in the crank chamber, and the release passage composed of the oil supply passage, the lubrication passage, the first radial hole and the outflow hole is communicated to that region, in which the lubricating oil is present in abundance, so that it is possible to supply the lubricating oil in the crank chamber to the shaft seal device, thus enabling improving durability of a rubber material for the shaft seal device. 
     With a swash plate compressor, when a drive shaft is rotated at high speed, an improvement in sliding characteristic is demanded between cylinder bores and pistons, and between a swash plate and respective shoes, and so on. Also, when a drive shaft is rotated at low speed, lubricating oil in refrigerating gas discharged to an external refrigerating circuit outside a swash plate compressor is demanded of reduction in quantity to demonstrate a high refrigerating capacity. 
     In this respect, with the swash plate compressor disclosed in the aforementioned patent application publication, the release passage communicates an oil rich region, in which lubricating oil is present in abundance in the crank chamber, in a predetermined cross sectional area with the suction chamber at all times, so that the lubricating oil in the crank chamber is made excessively small or large in quantity irrespective of the rotating speed of the drive shaft. When the lubricating oil in the crank chamber is excessively large in quantity while the drive shaft is increased in rotating speed, the swash plate agitates the lubricating oil excessively, so that the lubricating oil is liable to generate heat due to shearing and to decrease in viscosity. In this case, there is a fear in lubrication of sliding portions. Also, when the lubricating oil in the crank chamber is excessively small in quantity while the drive shaft is decreased in rotating speed, the lubricating oil in refrigerating gas discharged to a refrigerating circuit outside the swash plate compressor is increased in quantity and so the refrigerating capacity becomes insufficient. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide a swash plate compressor capable of realizing an excellent sliding characteristic when a drive shaft is rotated at high speed, and a high refrigerating capacity when the drive shaft is rotated at low speed. 
     Refrigerating gas mixed with lubricating oil is adopted in a swash plate compressor. According to experiments conducted by the inventors of the present invention, there are present an oil rich region, in which the lubricating oil is large in quantity, and an oil poor region, in which the lubricating oil is small in quantity, in a crank chamber of a swash plate compressor. For example, the oil rich region is present in an outer peripheral region of the crank chamber, and the oil poor region is present in an inner peripheral region of the crank chamber, that is, a region away from a wall surface of the crank chamber. This is because a swash plate rotates together with a drive shaft in the crank chamber and the lubricating oil is forced out into the outer peripheral region of the crank chamber by centrifugal force. Also, the lubricating oil is present in abundance on a peripheral surface of a cylinder bore. The invention has been accomplished based on these ascertainments. 
     The invention provides a swash plate compressor comprising: a housing including a cylinder bore, a suction chamber, a discharge chamber and a crank chamber, a drive shaft rotatably supported by the housing, a swash plate supported on the drive shaft in the crank chamber, a piston reciprocatingly accommodated in the cylinder bore, a motion conversion mechanism provided between the swash plate and the piston to convert a wobbling motion of the swash plate into reciprocation of the piston, and a release passage for communication of the crank chamber to the suction chamber, the compressor being characterized in that the release passage includes a first passage communicated to an oil rich region, in which lubricating oil is large in quantity in the crank chamber, a valve mechanism is provided to increase opening degree of the first passage as the drive shaft is increased in rotating speed, and the valve mechanism is provided on the first passage to be displaced by centrifugal force. 
     With the swash plate compressor of the invention, when the drive shaft is rotated at high speed, the valve mechanism increases opening degree of the first passage. Therefore, refrigerating gas containing a large quantity of the lubricating oil in the crank chamber is moved to the suction chamber by the first passage, opening degree of which is increased. Therefore, the lubricating oil in the crank chamber becomes moderate in quantity and so the swash plate does not agitate the lubricating oil so much, so that the lubricating oil is hard to generate heat due to shearing and hard to decrease in viscosity. Therefore, sliding portions are favorably lubricated. Also, refrigerating gas sucked from the suction chamber contains a large quantity of the lubricating oil and sliding portions between the cylinder bore and the piston are favorably lubricated. In addition, while the lubricating oil contained in refrigerating gas discharged to a refrigerating circuit outside the swash plate compressor are increased in quantity at this time, no problem is caused in refrigerating capacity since the piston reciprocates at high speed. 
     In addition, with the swash plate compressor, while the lubricating oil in the crank chamber is increased in quantity when the drive shaft is rotated at low speed, the swash plate or the like only agitates the lubricating oil at low speed, so that the lubricating oil is not decreased so much in viscosity and the lubricating oil is little raised in temperature. Therefore, sliding portions are still lubricated favorably. 
     The valve mechanism is provided on the first passage to be displaced by the centrifugal force. A mechanical valve mechanism is adopted, in which a mass body is displaced by the centrifugal force and a valve body is actuated. Therefore, an increase in the centrifugal force causes a displacement in a direction, in which the first passage is increased in opening degree, and a decrease in the centrifugal force causes a displacement in a direction, in which the first passage is decreased in opening degree. 
     Accordingly, with the swash plate compressor of the invention, it is possible to realize an excellent sliding characteristic when a drive shaft is rotated at high speed, and a high refrigerating capacity when the drive shaft is rotated at low speed. 
     Other aspects and advantages of the invention will be apparent from embodiments disclosed in the attached drawings, illustrations exemplified therein, and the concept of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described in more detail along with the concept and advantages thereof by referring to the attached drawings and the detailed description of the preferred embodiments below. 
         FIG. 1  is a cross sectional view showing a swash plate compressor according to EMBODIMENT 1. 
         FIG. 2  relates to the swash plate compressor according to EMBODIMENT 1 and is a cross sectional view showing an essential part thereof. 
         FIG. 3  relates to the swash plate compressor according to EMBODIMENT 1 and is a cross sectional view showing, in enlarged scale, an essential part thereof while a drive shaft is rotated at low speed. 
         FIG. 4  relates to the swash plate compressor according to EMBODIMENT 1 and is a cross sectional view showing, in enlarged scale, an essential part thereof while the drive shaft is rotated at high speed. 
         FIG. 5  relates to the swash plate compressor according to EMBODIMENT 1 and is a graph illustrating the relationship between the rotating speed of the drive shaft and a throttle area. 
         FIG. 6  is a cross sectional view showing a swash plate compressor according to EMBODIMENT 2. 
         FIG. 7  is a cross sectional view showing a swash plate compressor of a modified example. 
         FIG. 8  is a cross sectional view showing a swash plate compressor of a further modified example. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     Embodiments 1 and 2, in which the invention is embodied, will be described below with reference to the drawings. 
     Embodiment 1 
     A swash plate compressor according to EMBODIMENT 1 is of a variable displacement type used for air-conditioning of a vehicle. As shown in  FIG. 1 , the compressor includes a housing composed of a cylinder block  1 , a front housing  3  and a rear housing  5 , and a plurality of cylinder bores  1   a  extending in parallel to an axis of a drive shaft  7  are provided on the cylinder block  1  to extend therethrough. In addition, the left in  FIG. 1  indicates the front of the compressor and the right indicates the rear of the compressor. 
     Formed on the rear housing  5  are a suction chamber  11  and a discharge chamber  13 , which are communicated to the respective cylinder bores  1   a  through a valve unit  9 . Also, the front housing  3  and the cylinder block  1  define a crank chamber  15  and axial holes  3   a,    1   b  are formed on the front housing  3  and the cylinder block  1 . A shaft seal device  17  is provided in the axial hole  3   a.  A rubber material is used for the shaft seal device  17 . Also, a plain bearing  19  is provided in the axial hole  1   b.  A receiving chamber  1   c  communicated to the axial hole  1   b  is formed centrally of a rear end of the cylinder block  1 , the receiving chamber  1   c  is opposed to the valve unit  9 . 
     The drive shaft  7  is supported to be able to rotate by the shaft seal device  17 , etc. in a state, in which one end thereof is exposed from the front housing  3  and a central portion thereof faces into the crank chamber  15 . A pulley and an electromagnetic clutch, both of which are not shown, are connected to the drive shaft  7 , and the drive shaft  7  is rotationally driven by a drive source, such as an engine, etc. through a belt stretched round the pulley and the electromagnetic clutch. Also, pistons  21 , respectively, are received in the respective cylinder bores  1   a  to be able to reciprocate, the respective pistons  21 , respectively, defining compression chambers in the cylinder bores  1   a.    
     A lug plate  23  receiving compressive reaction force is fixed to the drive shaft  7  in the crank chamber  15 , and a thrust bearing  25  and a plain bearing  27  are provided between the lug plate  23  and the front housing  3 . Also, the drive shaft  7  is inserted through a swash plate  29 , of which inclination to an imaginary plane perpendicular to the drive shaft  7  is variable. A hinge portion  23   a  is formed on the lug plate  23  to be directed toward the swash plate  29 , a hinge portion  29   a  is provided on the swash plate  29  to be directed toward the lug plate  23 , and the hinge portions  23   a,    29   a  constitute a linkage  31 . Also, a push spring  33  is provided between the lug plate  23  and the swash plate  29  to bias the both in a direction, in which the both separate from each other. 
     Also, pairs of front and rear shoes  35  are provided between the swash plate  29  and the respective pistons  21 . The shoe  35  on a front side is provided between a front surface of the swash plate  29  and a front seat surface of the piston  21 , and the shoe  35  on a rear side is provided between a rear surface of the swash plate  29  and a rear seat surface of the piston  21 . The respective shoes  35  are substantially semi-spherical in shape. The respective shoes  35  serve as a motion conversion mechanism. 
     Formed on the drive shaft  7  are a first hole  37  extending in a radial direction, an outflow hole  39  communicated to the first hole  37  to extend coaxially with an axis in an axial direction to extend to a rear end of the drive shaft  7 , and a valve hole  41  communicated to the outflow hole  39  to extend in a radial direction. 
     As shown in  FIG. 2 , the first hole  37  is disposed between the lug plate  23  and the front housing  3  and formed over an extent of a radius of the drive shaft  7  from an axis of the drive shaft  7  to an outer periphery thereof. An oil guide groove  3   b  is formed on the front housing  3  to extend between the front housing  3  and the lug plate  23  from an outer peripheral region of the crank chamber  15  to face the thrust bearing  25 . Also, an oil guide hole  3   c  is formed on the front housing  3  to be communicated to the oil guide groove  3   b  to face the plain bearing  27  and the shaft seal device  17 . The oil guide hole  3   c  faces the shaft seal device  17  in the axial hole  3   a  to be communicated to the first hole  37 . The oil guide groove  3   b  and the oil guide hole  3   c  serve as an oil guide path. 
     As shown in  FIG. 1 , the rear end of the drive shaft  7  projects into the receiving chamber  1   c  and a rear end of the outflow hole  39  is closed by a plug member  43 . The valve hole is formed a little ahead of the plug member  43 . As shown in  FIGS. 3 and 4 , the valve hole  41  is provided through the drive shaft  7  to communicate the outflow hole  39  to the receiving chamber  1   c.    
     A valve mechanism  45  is provided round the valve hole  41 . The valve mechanism  45  includes a spherical-shape valve body  47  that can be seated on one opening  41   a  of the valve hole  41 , and a case  49  fixed to the drive shaft  7  around the valve hole  41 . The valve body  47  serves also as a mass body. The case  49  includes a valve chamber  49   a  on a side toward the opening  41   a.  Provided in the valve chamber  49   a  are a first spring  51  that biases the valve body  47  in a direction away from the opening  41   a,  and a second spring  53  having a bias that biases the valve body  47  in a direction toward the opening  41   a.  The valve chamber  49   a  is communicated to the receiving chamber  1   c  through a communication port  49   b  formed on the case  49 . 
     As shown in  FIG. 1 , a throttle hole  9   a  for communication of the receiving chamber  1   c  with the suction chamber  11  is provided on the valve unit  9  to extend therethrough. Also, a second hole  55  is formed on the cylinder block  1  and the valve unit  9  to provide communication between the suction chamber  11  and an inner peripheral region of the crank chamber  15 , that is, a region close to the drive shaft  7 . A throttle  55   a  is formed on the second hole  55  in the valve unit  9 . The oil guide groove  3   b,  the oil guide hole  3   c,  the first hole  37 , the outflow hole  39 , the valve hole  41 , the communication port  49   b,  the receiving chamber  1   c,  the throttle hole  9   a,  and the second hole  55  constitute a release passage. The oil guide groove  3   b,  the oil guide hole  3   c,  the first hole  37 , the outflow hole  39 , the valve hole  41 , the communication port  49   b,  the receiving chamber  1   c,  and the throttle hole  9   a  constitute a first passage. Also, the second hole  55  constitutes a second passage. In addition, the communication port  49   b  and the throttle hole  9   a  are set to be equal to or larger in opened cross sectional area than the opening  41   a  of the valve hole  41 . 
     Also, a capacity control valve  57  is received in the rear housing  5 . The capacity control valve  57  is communicated to the suction chamber  11  through a detection passage  59  and provides communication between the discharge chamber  13  and the crank chamber  15  through the detection passage  59 . The capacity control valve  57  detects pressure in the suction chamber  11  to change opening degree of a supply passage  61  to change the discharge capacity of a compressor. 
     A pipe  63  is connected to the discharge chamber  13 , the pipe  63  being connected to the suction chamber  11  through a check valve  65 , a condenser  67 , an expansion valve  69 , and an evaporator  71 . The compressor, the check valve  65 , the condenser  67 , the expansion valve  69 , the evaporator  71 , and the pipe  63  constitute a refrigerating circuit. Refrigerating gas mixed with lubricating oil is charged in the refrigerating circuit. 
     With the compressor thus constructed, the capacity control valve  57  adjusts pressure in the crank chamber  15  on the basis of pressure in the suction chamber  11  and a flow rate of refrigerating gas to change an angle of the swash plate  29  to the drive shaft  7  to change a discharge capacity thereof. 
     Also, with the compressor, when the drive shaft  7  is rotated at high speed while a vehicle is running at high speed, the valve body  47  of the valve mechanism  45  is caused by large centrifugal force and the bias of the first spring  51  to move away from the axis of the drive shaft  7  against the bias of the second spring  53 , whereby the valve body  47  increases opening degree of the opening  41   a  as shown in  FIG. 4 . 
     Therefore, opening degree, at which the valve hole  41  is communicated to the communication port  49   b,  increases and opening degree, at which the first hole  37  shown in  FIG. 2  is communicated to the communication port  49   b,  increases. At this time, the second hole  55  provides communication in a predetermined cross sectional area between the crank chamber  15  and the suction chamber  11 . Therefore, as shown in  FIG. 5 , a throttle area, in which the crank chamber  15  and the suction chamber  11  are communicated to each other, becomes large. That is, the single valve mechanism  45  increases a ratio, at which the first hole  37  occupies the release passage, and decreases a ratio, at which the second hole  55  occupies the release passage. 
     In an outer peripheral region of the crank chamber  15  shown in  FIG. 2 , the lubricating oil is present in abundance and the lubricating oil is led to the first hole  37  through the oil guide groove  3   b  and the oil guide hole  3   c.  At this time, the lubricating oil is led to the first hole  37  through the shaft seal device  17 , so that a large quantity of the lubricating oil is supplied to the shaft seal device  17  to heighten the shaft seal device  17  in durability. 
     Owing to the first hole  37  increased in that ratio, at which it occupies the release passage, refrigerating gas disposed in the crank chamber  15  and containing a large quantity of the lubricating oil is led to the receiving chamber  1   c  through the outflow hole  39 , the valve hole  41 , and the communication port  49   b  and further moved to the suction chamber via the throttle hole  9   a.  Therefore, the lubricating oil in the crank chamber  15  becomes moderate in quantity and so the swash plate  29  does not agitate the lubricating oil so much, so that the lubricating oil is hard to generate heat due to shearing and hard to decrease in viscosity. Therefore, sliding portions between the swash plate  29  and the respective shoes  35  are favorably lubricated. Also, refrigerating gas sucked from the suction chamber  11  contains a large quantity of the lubricating oil and sliding portions between the cylinder bores  1   a  and the pistons  21  are favorably lubricated. Thereby, an excellent durability exhibits itself at high speed. 
     In addition, while the lubricating oil contained in refrigerating gas discharged to the refrigerating circuit outside the compressor are increased in quantity at this time, no problem is caused in refrigerating capacity since the pistons  21  reciprocate at high speed. 
     Also, when the drive shaft  7  is rotated at low speed while a vehicle is running at low speed, the valve body  47  of the valve mechanism  45  resists the bias of the first spring  51  because of small centrifugal force and yields to the bias of the second spring  53  to approach the axis of the drive shaft  7  as shown in  FIG. 3 , and thus the valve body  47  decreases opening degree of the opening  41   a.  When the drive shaft  7  is rotated at a further low speed, the valve body  47  is seated on the opening  41   a  to close the valve hole  41 . 
     Therefore, opening degree, at which the valve hole  41  is communicated to the communication port  49   b,  decreases and opening degree, at which the first hole  37  shown in  FIG. 2  is communicated to the communication port  49   b,  decreases. Also, at this time, the second hole  55  provides communication in a predetermined cross sectional area between the crank chamber  15  and the suction chamber  11 . Therefore, as shown in  FIG. 5 , a throttle area, in which the crank chamber  15  and the suction chamber  11  are communicated to each other, becomes small. That is, the single valve mechanism  45  decreases a ratio, at which the first hole  37  occupies the release passage, and increases a ratio, at which the second hole  55  occupies the release passage. 
     The lubricating oil is small in quantity in an inner peripheral region of the crank chamber  15  shown in  FIG. 2 , that is, a region close to the drive shaft  7 , and refrigerating gas not containing much of the lubricating oil is led into the second hole  55  from there. 
     Owing to the second hole  55  increased in that ratio, at which it occupies the release passage, refrigerating gas not containing much of the lubricating oil within the crank chamber  15  is moved to the suction chamber  11  via the throttle  55   a.  Therefore, the lubricating oil contained in refrigerating gas discharged to the refrigerating circuit outside the compressor is decreased in quantity, so that a high refrigerating capacity exhibits itself. 
     Further, with the swash plate compressor, the first hole  37  is closed when the drive shaft  7  is rotated at low speed. Accordingly, the sum of the cross sectional area of the opening of the release passage decreases whereby refrigerating gas moving to the suction chamber  11  from the crank chamber  15  is decreased in quantity, and refrigerating gas circulated within the swash plate compressor is decreased in quantity whereby refrigerating gas used for the proper object is increased in quantity and the swash plate compressor is improved in performance. 
     In addition, while the lubricating oil in the crank chamber  15  is increased in quantity, the swash plate  29  only agitates the lubricating oil at low speed, so that the lubricating oil is little raised in temperature and the lubricating oil is not decreased so much in viscosity. Therefore, sliding portions are still lubricated favorably. 
     Accordingly, the compressor can demonstrate an excellent sliding characteristic when the drive shaft  7  is rotated at high speed, and can demonstrate a high refrigerating capacity when the drive shaft  7  is rotated at low speed. 
     Embodiment 2 
     With a swash plate compressor according to EMBODIMENT 2, a plurality of cylinder bores  2   a  extending in parallel to an axis of a drive shaft  8  are provided on a cylinder block  2  to extend therethrough as shown in  FIG. 6 . Formed on a rear housing  6  are a suction chamber  12  and a discharge chamber  14 , which are communicated to the respective cylinder bores  2   a  through a valve unit  10 . Also, a front housing  4  and the cylinder block  2  define a crank chamber  16  and axial holes  4   a,    2   b  are formed on the front housing  4  and the cylinder block  2 . A shaft seal device  18  and a plain bearing  20  are provided in the axial hole  4   a.  A rubber material is used for the shaft seal device  18 . Also, a plain bearing  22  is provided in the axial hole  2   b.  A receiving chamber  2   c  communicated to the axial hole  2   b  is formed centrally of a rear end of the cylinder block  2 , the receiving chamber  2   c  being opposed to the valve unit  10 . 
     The drive shaft  8  is supported by the shaft seal device  18 , etc. in a state to be able to rotate, in which one end thereof is exposed from the front housing  4  and a central portion thereof faces the crank chamber  16 . Also, pistons  24 , respectively, are received in the respective cylinder bores  2   a  to be able to reciprocate, the respective pistons  24  defining compression chambers in the cylinder bores  2   a.    
     A lug plate  26  receiving compressive reaction force is fixed to the drive shaft  8  in the crank chamber  16 , and a thrust bearing  28  is provided between the lug plate  26  and the front housing  4 . Also, the drive shaft  8  is inserted through a swash plate  30  to make the same variable in inclination angle. A linkage  32  is formed between the lug plate  26  and the swash plate  30 . Also, push springs  34 ,  36  are provided between the lug plate  26  and the swash plate  30  and between the swash plate and the drive shaft  8 . Also, pairs of front and rear shoes are provided between the swash plate  30  and the respective pistons  24 . 
     The drive shaft  8  comprises a body  8   a,  of which a rear end is formed to be cylindrical-shaped, and a tubular body  8   b  in the form of a cylinder inserted from the rear end of the body  8   a  to be fixed in the body  8   a.  A first hole  40  being annular and extending in an axial direction is defined between the body  8   a  and the tubular body  8   b.  A guide hole  26   a  formed midway thereof with a step is formed on the lug plate  26  to be perpendicular to an axis. The guide hole  26   a  is communicated at an inner end thereof to the first hole  40  and communicated at an outer end thereof to an outer peripheral region of the crank chamber  16 . A valve chamber  26   b  is defined midway the guide hole  26   a  in the lug plate  26  and a valve mechanism  42  is provided in the valve chamber  26   b.  The valve mechanism  42  comprises a valve body  42   a  that can be seated on an opening of the guide hole  26   a  on an inner end side, and a spring  42   b  that biases the valve body  42   a  in a direction of seating. The valve body  42   a  serves as a mass body. A cylindrical-shaped cover body  26   c  is press fitted into the guide hole  26   a  outside the valve chamber  26   b  to support one end of the spring  42   b.    
     Formed on the body  8   a  of the drive shaft  8  are a second hole  44  extending radially, and a communication hole  46  communicated to the second hole  44  to extend coaxially with an axis in an axial direction. Formed on the tubular body  8   b  is an outflow hole  48  communicated to the communication hole  46  to extend to a rear end of the drive shaft  8 . The second hole  44  is disposed between the shaft seal device  18  and the plain bearing  20  to be formed over an extent of a radius of the drive shaft  8  from an axis of the drive shaft  8  to an outer periphery thereof. An oil guide hole  4   b  is formed on the front housing  4  to open to an inner peripheral region of the crank chamber  16  between the front housing  4  and the lug plate  26 . The oil guide hole  4   b  faces the shaft seal device  18  in the axial hole  4   a  to be communicated to the second hole  44 . The rear end of the drive shaft  8  projects into the receiving chamber  2   c.    
     A throttle hole  10   a  for communication of the receiving chamber  2   c  with the suction chamber  12  is provided on the valve unit  10  to extend therethrough. The guide hole  26   a,  the valve chamber  26   b,  the first hole  40 , the oil guide hole  4   b,  the second hole  44 , the communication hole  46 , the outflow hole  48 , the receiving chamber  2   c,  and the throttle hole  10   a  constitute a release passage. The guide hole  26   a,  the valve chamber  26   b,  the first hole  40 , the receiving chamber  2   c,  and the throttle hole  10   a  constitute a first passage. Also, the oil guide hole  4   b,  the second hole  44 , the communication hole  46 , the outflow hole  48 , the receiving chamber  2   c,  and the throttle hole  10   a  constitute a second passage. The remaining construction is the same as that of EMBODIMENT 1. 
     With the compressor, when the drive shaft  8  is rotated at high speed while a vehicle is running at high speed, or the like, the valve body  42   a  of the valve mechanism  42  is caused by large centrifugal force to get away from the axis of the drive shaft  8  against the bias of the spring  42   b,  whereby the valve body  42   a  increases opening degree of the guide hole  26   a.  At this time, the second hole  44  provides communication in a predetermined cross sectional area between the crank chamber  16  and the suction chamber  12 . Therefore, a throttle area, in which the crank chamber  16  and the suction chamber  12  are communicated to each other, becomes large. Therefore, the single valve mechanism  42  is increased a ratio, at which the first hole  40  occupies the release passage, and decreased a ratio, at which the second hole  44  occupies the release passage. 
     Also, when the drive shaft  8  is rotated at low speed while a vehicle is running at low speed, or the like, the valve body  42   a  of the valve mechanism  42  is caused by the bias of the spring  42   b  to approach the axis of the drive shaft  8  against small centrifugal force, and thus the valve body  42   a  decreases opening degree of the guide hole  26   a.  When the drive shaft  8  is rotated at a further low speed, the valve body  42   a  is seated on the guide hole  26   a.  At this time, the second hole  44  provides communication in a predetermined cross sectional area between the crank chamber  16  and the suction chamber  12 . Therefore, a throttle area, in which the crank chamber  16  and the suction chamber  12  are communicated to each other, becomes small. Therefore, the single valve mechanism  42  is decreased a ratio, at which the first hole  40  occupies the release passage, and increased a ratio, at which the second hole  44  occupies the release passage. 
     Accordingly, with the compressor, the same function and effect as those of EMBODIMENT 1 can be produced. With the compressor, since the oil guide hole  4   b  is communicated to an inner peripheral region of the crank chamber  16  and only a small quantity of the lubricating oil is supplied to the oil guide hole  4   b  when the compressor is rotated at high speed, the compressor of EMBODIMENT 1 is excellent in terms of durability of the rubber material for the shaft seal device  18  when the compressor is rotated at high speed. However, the lubricating oil can be supplied to the shaft seal device  18  at all times. 
     While the invention has been described with respect to EMBODIMENT 1 and EMBODIMENT 2, it goes without saying that the invention is not limited to EMBODIMENT 1 and EMBODIMENT 2 but can be appropriately changed within a scope not departing from the gist thereof and applied. 
     For example, as shown in  FIG. 7 , it is possible in the compressor of EMBODIMENT 1 to remove the throttle  55  as a second passage and to form on the drive shaft  7  a throttle  55   b,  which provides communication between the outflow hole  39  and the receiving chamber  1   c  and is the same in diameter as the throttle  55   a,  as a second passage. 
     With such construction, a second passage is easy to form; the lubricating oil can be supplied to the shaft seal device  18  at all times, and the same effect as that of EMBODIMENT 2 can be produced. In addition, in this case, the throttle hole  9   b  is set to be equal to or larger in opened cross sectional area than the sun of the opened cross sectional areas of the opening  41   a  of the valve hole  41  and the throttle  55   b.    
     Also, as shown in  FIG. 8 , it is possible to remove the throttle  55  as a second passage and to provide a groove  55   c,  which bypasses the valve body  47 , as a second passage on the opening  41   a  of the valve hole  41 . With such construction, the same effect can be produced. 
     Also, with the compressor of EMBODIMENT 2, it is preferred that an opening of the guide hole  26   a  on an outer end side thereof be forward in a direction of rotation of the lug plate  26  to facilitate taking the lubricating oil in the crank chamber  16  into the guide hole  26   a.    
     Also, in the case where radial bearings using rollers are adopted in place of the plain bearings  19 ,  22  in the compressors of EMBODIMENT 1 and EMBODIMENT 2, a release passage may be provided between the respective rollers and ratios, at which the first passage and the second passage occupy the release passage, may be changed. Also, the linkages  31 ,  32  are not limited to those in the embodiments but various arrangements may be adopted. 
     The swash plate compressor of the invention may be of a fixed displacement type, in which a swash plate is invariable in inclination angle, or may be of a variable displacement type, in which a swash plate is variable in inclination angle. 
     Also, with the swash plate compressor of the invention, the release passage may be enough to communicate the crank chamber to the suction chamber, may be one for direct communication of the crank chamber to the suction chamber, or may be one for indirect communication of the crank chamber to the suction chamber through a suction passage, etc. communicated to the suction chamber. The release passage suffices to include the first passage, or may include another passage. 
     The first passage is communicated to any one of those regions, in which lubricating oil is present in abundance. Regions, in which the lubricating oil is present in abundance, are determined by intercomparison with other regions. 
     The release passage can include a second passage communicated to that region, in which lubricating oil is small in quantity in the crank chamber. The valve mechanism can increase a ratio, at which the first passage occupies the release passage, as the drive shaft is increased in rotating speed, and can decrease a ratio, at which the second passage occupies the release passage, as the drive shaft is decreased in rotating speed. 
     In this case, the release passage comprises the first passage and the second passage and refrigerating gas not containing much of the lubricating oil in the crank chamber can be moved to the suction chamber by the second passage. Therefore, the valve mechanism is liable to change a ratio, at which the first passage occupies the release passage, so that an improvement in responsibility relative to the rotating speed is achieved. 
     Also, with the swash plate compressor, when the drive shaft is rotated at low speed, the valve mechanism decreases a ratio, at which the first passage occupies the release passage. Therefore, refrigerating gas containing a large quantity of lubricating oil in the crank chamber is not moved so much to the suction chamber by the first passage decreased in that ratio, at which it occupies the release passage, but refrigerating gas not containing much of the lubricating oil in the crank chamber is moved to the suction chamber by the second passage. Therefore, the lubricating oil contained in refrigerating gas discharged to a refrigerating circuit outside the swash plate compressor are decreased in quantity, so that a high refrigerating capacity is demonstrated. 
     Further, with the swash plate compressor, when the drive shaft is rotated at low speed, the sum of the cross sectional area of the opening of the release passage decreases whereby refrigerating gas moving to the suction chamber from the crank chamber is decreased in outflow and refrigerating gas circulated within the compressor is decreased in quantity, so that refrigerating gas used for the proper object is increased in quantity and the compressor is improved in performance. In particular, with a clutchless type swash plate compressor, in which power is transmitted to a drive shaft of the swash plate compressor at all times in operation of a drive source, refrigerating gas is only circulated within the compressor when cooling is not needed, but refrigerating gas as circulated can be made minimum when the drive shaft is rotated at low speed, so that it is possible to realize demonstration of an excellent sliding characteristic when the drive shaft is rotated at high speed, and reduction in power for the compressor when the drive shaft is rotated at low speed. 
     The second passage is preferably formed with a throttle. 
     In this case, refrigerating gas not containing much of the lubricating oil in the crank chamber is made difficult to move to the suction chamber, so that the effect of the invention produced by the lubricating oil becomes conspicuous. 
     With the swash plate compressor of the invention, the swash plate can be supported to be variable in inclination angle. Also, a lug plate receiving compressive reaction force can be fixed to the drive shaft to be able to rotate integrally. Further, an oil guide path can be formed on the housing to extend between the housing and the lug plate from an outer peripheral region of the crank chamber. The first passage is preferably communicated to the oil guide path. 
     According to experiments conducted by the inventors of the present invention, an outer peripheral region of a crank chamber in a swash plate compressor is a region, in which lubricating oil is present in abundance, so that it is possible to readily lead the lubricating oil to a first passage via the oil guide path. 
     A shaft seal device can be provided between the housing and the drive shaft to seal the drive shaft exposed from the housing. The first passage is preferably communicated to the oil guide path via the shaft seal device. 
     In this case, by supplying a large quantity of lubricating oil to the shaft seal device, it is possible to improve durability of a rubber material for the shaft seal device. 
     With the swash plate compressor of the invention, the swash plate can be supported to be variable in inclination angle. Also, a lug plate receiving compressive reaction force can be fixed to the drive shaft to be able to rotate integrally. Further, the first passage can include a guide hole formed on the lug plate and opened to an outer peripheral region of the crank chamber. 
     According to results of tests made by inventors of the present application, an outer peripheral region of a crank chamber in a swash plate compressor is a region, in which lubricating oil is present in abundance, so that it is possible to readily lead the lubricating oil to a first passage via the oil guide hole. 
     With the swash plate compressor of the invention, a shaft seal device can be provided between the housing and the drive shaft to seal the drive shaft exposed from the housing. Also, the second passage is preferably opened to the crank chamber in the vicinity of the shaft seal device. 
     In this case, lubricating oil can be supplied to the shaft seal device at all times, so that the shaft seal device can be improved in durability. 
     EXPLANATION OF INDUSTRIAL APPLICATION OF INVENTION 
     The invention can be made use of in air-conditioning apparatuses for vehicles.