Patent Publication Number: US-2018038372-A1

Title: Rotating cylinder type compressor

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is based on Japanese Patent Application No. 2015-66056 filed on Mar. 27, 2015, the disclosure of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a rotating cylinder type compressor, in which a cylinder is rotated, and a compression chamber is defined in the cylinder. 
     BACKGROUND ART 
     A rotating cylinder type compressor is conventionally known, in which a cylinder is rotated and a compression chamber is defined in the cylinder. Specifically, a volume of the compression chamber is changed to compress and discharge fluid. 
     For example, Patent Literature 1 discloses a rotating cylinder type compressor including a cylinder, a rotor, and a vane. The cylinder is formed integrally with a rotor of an electric motor part (electric motor part). The rotor has a cylindrical shape and is arranged inside the cylinder. The vane has a tabular shape, and is slidably fitted to a groove portion (slit part) formed in the rotor to partition a compression chamber. 
     In this kind of rotating cylinder type compressor, the vane is displaced by rotating the cylinder and the rotor about rotation axes different from each other in the interlocked manner, so as to change the volume of the compression chamber. Furthermore, in the rotating cylinder type compressor of Patent Literature 1, a compression mechanism part is arranged on the inner circumference side of the electric motor part to downsize the compressor as a whole. 
     PRIOR ART LITERATURES 
     Patent Literature 
     Patent Literature 1: JP 2012-67735 A 
     SUMMARY OF INVENTION 
     In order to increase the discharge capability of the rotating cylinder type compressor of Patent Literature 1, the outer diameter of the compression chamber (the inner diameter of the cylinder) may be increased to increase the volume of the compression chamber (discharge capacity). 
     However, if the inner diameter of the cylinder is made larger to increase the discharge capability, the outer diameter of the electric motor part arranged on the outer circumference side of the cylinder is also made larger. In this case, it becomes difficult to acquire the above-mentioned downsizing effect as a whole compressor. Moreover, if the discharge capacity is increased, the torque fluctuations at a time of operating the compressor will also increase. As a result, noise and vibration may increase as the whole compressor. 
     The present disclosure is aimed to provide a rotating cylinder type compressor in which a volume of a compression chamber can be increased without size increase in the radial direction. 
     According to an aspect of the present disclosure, a rotating cylinder type compressor includes: a cylinder having a cylindrical shape and rotating about a central axis; a first rotor and a second rotor arranged inside the cylinder, each of the first rotor and the second rotor having a cylindrical shape and rotating about an eccentric axis eccentric to the central axis of the cylinder; a shaft that rotatably supports the first rotor and the second rotor; a first vane slidably fitted to a first groove portion defined in the first rotor to define a first compression chamber between an outer circumference surface of the first rotor and an inner circumference surface of the cylinder; and a second vane slidably fitted to a second groove portion defined in the second rotor to define a second compression chamber between an outer circumference surface of the second rotor and an inner circumference surface of the cylinder. The first rotor and the second rotor are arranged in an extending direction of the central axis of the cylinder. 
     Due to the first rotor and the second rotor, the first compression chamber and the second compression chamber can be formed. Therefore, the total volume of the first compression chamber and the second compression chamber (the sum of discharge capacities) can be easily increased. Furthermore, since the first rotor and the second rotor are arranged side by side in the center axial direction of the cylinder, the total discharge capacity can be increased without increase in the outer diameter of the cylinder. 
     As a result, a rotating cylinder type compressor can be provided, in which the capacity of the compression chamber can be increased without causing enlargement in the radial direction. 
     Moreover, the eccentric axis of the first rotor and the eccentric axis of the second rotor may be arranged on the same axis. In this case, the shaft can be formed easily, because it is not necessary to form portions corresponding to eccentric axes different from each other in the shaft. 
     Furthermore, a rotation angle of the cylinder where the fluid pressure of the first compression chamber reaches the maximum pressure and a rotation angle of the cylinder where the fluid pressure of the second compression chamber reaches the maximum pressure may be shifted from each other by 180 degrees. Accordingly, the torque fluctuations can be restricted from increasing, while the volume of the compression chamber is increased. Thus, noise and vibration can be effectively restricted from increasing as the whole compressor. 
     In addition, “shifted from each other by 180 degrees” does not only mean a shift by just 180 degrees, but also means a shift by 180 degrees with a slight tolerance in the manufacturing or the assembling. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. 
         FIG. 1  is an axial cross-sectional view illustrating a compressor of a first embodiment. 
         FIG. 2  is a sectional view taken along a line II-II of  FIG. 1 . 
         FIG. 3  is a sectional view taken along a line III-III of  FIG. 1 . 
         FIG. 4  is an exploded perspective view illustrating a compression mechanism part of the compressor of the first embodiment. 
         FIG. 5  is a diagram explaining operation states of the compressor of the first embodiment. 
         FIG. 6  is a graph illustrating torque fluctuations of the compressor of the first embodiment. 
         FIG. 7  is a sectional view illustrating a compressor of a second embodiment, and corresponds to  FIG. 3 . 
         FIG. 8  is a sectional view illustrating a compressor of a third embodiment, and corresponds to  FIG. 3 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
     Hereafter, a first embodiment is described with reference to the drawings. A rotating cylinder type compressor  1  of this embodiment (hereafter referred as the compressor  1 ) is applied to a vapor-compression refrigeration cycle apparatus which cools air to be sent to a cabin in an air-conditioner for a vehicle. The compressor  1  compresses and discharges refrigerant which is a fluid to be compressed in the refrigeration cycle apparatus. 
     The refrigeration cycle apparatus adopts HFC base refrigerant (specifically, R134a) as a refrigerant, and defines a sub-critical refrigeration cycle in which the high-pressure side refrigerant pressure does not exceed the critical pressure of refrigerant. Furthermore, the refrigerant slightly contains a lubricating oil lubricating the sliding part of the compressor  11 , and a part of the oil circulates through the cycle with the refrigerant. 
     As shown in  FIG. 1 , the compressor  1  is an electric compressor including a compression mechanism part  20  that compresses and discharges the refrigerant, and an electric motor part (electric motor part)  30  that drives the compression mechanism part  20 , which are housed in a housing  10  which forms the outer shape. In addition, each arrow of up and down in  FIG. 1  indicates each direction of up and down in the state where the compressor  1  is mounted in the air-conditioner for a vehicle. 
     The housing  10  is configured by combining plural metal components, and has a tightly-closed container structure in which an approximately pillar-shaped space is defined. 
     More specifically, as shown in  FIG. 1 , the housing  10  includes a main housing  11  having a based cylindrical shape (the shape of a cup), a sub housing  12  having a based cylindrical shape arranged to close the opening of the main housing  11 , and a disk-shaped lid component  13  arranged to close the opening of the sub housing  12 . 
     A non-illustrated seal component such as O ring is disposed at contact parts among the main housing  11 , the sub housing  12 , and the lid component  13 , such that refrigerant does not leak from each contact part. 
     A discharge port  11   a  is formed in the cylindrical side surface of the main housing  11  to discharge the high-pressure refrigerant pressurized by the compression mechanism part  20  to the exterior of the housing  10  (specifically to the refrigerant inlet side of a condenser of the refrigeration cycle apparatus). An inlet port  12   a  is formed in the cylindrical side surface of the sub housing  12  to draw low-pressure refrigerant (specifically, low-pressure refrigerant flowed out of an evaporator of the refrigeration cycle apparatus) from the exterior of the housing  10 . 
     A housing side inlet passage  13   a  is defined between the sub housing  12  and the lid component  13  to introduce the low-pressure refrigerant drawn from the inlet port  12   a  to a first compression chamber Va and a second compression chamber Vb of the compression mechanism part  20 . Furthermore, a drive circuit (inverter)  30   a  which supplies electric power to the electric motor part  30  is attached to a surface of the lid component  13  opposite from the sub housing  12 . 
     The electric motor part  30  has a stator  31 . The stator  31  includes a stator core  31   a  formed with a metal magnetic material, and a stator coil  31   b  wound around the stator core  31   a . The stator  31  is fixed to the inner circumference surface of the cylindrical portion of the main housing  11  by means such as press fitting, shrinkage fitting or bolt tightening. 
     When electric power is supplied to the stator coil  31   b  from the drive circuit  30   a  through a non-illustrated sealed terminal (hermetic seal terminal), a revolving magnetic field occurs to rotate the cylinder  21  arranged at the inner circumference side of the stator  31 . The cylinder  21  is formed of a cylindrical metal magnetic material, and defines the first and second compression chambers Va and Vb of the compression mechanism part  20  to be mentioned later. 
     As shown in the sectional view such as  FIG. 2  and  FIG. 3 , a magnet (permanent magnet)  32  is fixed to the cylinder  21 . Thereby, the cylinder  21  functions as a rotor of the electric motor part  30 . The cylinder  21  rotates about a central axis C 1  by the revolving magnetic field produced by the stator  31 . 
     That is, the rotor of the electric motor part  30  and the cylinder  21  of the compression mechanism part  20  are integrally formed with each other in the compressors  1  of this embodiment. The rotor of the electric motor part  30  and the cylinder  21  of the compression mechanism part  20  may be formed separately from each other, and are unified into one component by means of press fitting or the like. Furthermore, the stator (the stator core  31   a  and the stator coil  31   b ) of the electric motor part  30  is arranged at the outer circumference side of the cylinder  21 . 
     Next, the compression mechanism part  20  is explained. In this embodiment, a first compression mechanism part  20   a  and a second compression mechanism part  20   b  are provided as two of the compression mechanism parts  20 . The fundamental configuration is the same between the first and second compression mechanism parts  20   a  and  20   b . Moreover, the first and second compression mechanism parts  20   a  and  20   b  are connected in parallel to a flow of the refrigerant inside the housing  10 . 
     As shown in  FIG. 1 , the first and second compression mechanism parts  20   a  and  20   b  are arranged in the center axial direction of the cylinder  21 . In this embodiment, of the two compression mechanism parts, the first compression mechanism part  20   a  is arranged adjacent to the bottom of the main housing  11 , and the second compression mechanism part  20   b  is arranged adjacent to the sub housing  12 . 
     In  FIG. 1  and  FIG. 4 , the second compression mechanism part  20   b  has components corresponding to components of the first compression mechanism part  20   a , and the alphabet at the end of the reference number is changed from “a” to “b”. For example, the second compression mechanism part  20   b  has the second rotor “ 22   b ” that is a component corresponding to the first rotor  22   a  of the first compression mechanism part  20   a.    
     The first compression mechanism part  20   a  includes the cylinder  21 , the first rotor  22   a , the first vane  23   a , and the shaft  24 . The second compression mechanism part  20   b  includes the cylinder  21 , the second rotor  22   b , the second vane  23   b , and the shaft  24 . That is, as shown in  FIG. 1 , a part of the cylinder  21  and the shaft  24  adjacent to the bottom of the main housing  11  configures the first compression mechanism part  20   a , and another part of the cylinder  21  and the shaft  24  adjacent to the sub housing  12  configures the second compression mechanism part  20   b.    
     The cylinder  21  rotates about the central axis C 1  as a rotor of the electric motor part  30 , and is a cylindrical component which forms the first compression chamber Va of the first compression mechanism part  20   a  and the second compression chamber Vb of the second compression mechanism part  20   b  inside. A first side plate  25   a  which is a component for closing the open end of the cylinder  21  is fixed to one end of the cylinder  21  in the axial direction by means such as bolt tightening. Moreover, a second side plate  25   b  is similarly fixed to the other end of the cylinder  21  in the axial direction. 
     Each of the first and second side plates  25   a  and  25   b  has a disk-shaped part spreading in a direction approximately perpendicular to the rotational axis of the cylinder  21 , and a boss part projected in the axial direction at the central part of the disk-shaped part. Furthermore, the boss part has a through hole passing through the first and second side plates  25   a  and  25   b.    
     A non-illustrated bearing mechanism is arranged in the respective through hole. The shaft  24  is inserted in the bearing mechanism, and the cylinder  21  is supported to be rotatable relative to the shaft  24 . The both ends of the shaft  24  are fixed to the housing  10  (specifically, the main housing  11  and the sub housing  12 ). Therefore, the shaft  24  does not rotate relative to the housing  10 . 
     The cylinder  21  of this embodiment forms inside the first compression chamber Va and the second compression chamber Vb separated from each other. A middle side plate  25   c  having a disk shape is arranged between the first rotor  22   a  and the second rotor  22   b  inside the cylinder  21  to partition the first compression chamber Va and the second compression chamber Vb. The middle side plate  25   c  has the same function as the first and second side plates  25   a  and  25   b.    
     That is, in the cylinder  21  of this embodiment, the both ends of the first compression mechanism part  20   a  in the axial direction are closed with the first side plate  25   a  and the middle side plate  25   c . Moreover, in the cylinder  21 , the both ends of the second compression mechanism part  20   b  in the axial direction are closed with the second side plate  25   b  and the middle side plate  25   c.    
     In other words, the first compression chamber Va is defined by the first side plate  25   a , the middle side plate  25   c , and the first rotor  22   a , and the second compression chamber Vb is defined by the second side plate  25   b , the middle side plate  25   c , and the second rotor  22   b . Furthermore, the middle side plate  25   c  is arranged between the first rotor  22   a  and the second rotor  22   b  to define the first compression chamber Va and the second compression chamber Vb. 
     In this embodiment, the cylinder  21  and the middle side plate  25   c  are integrally formed as one-piece component. Alternatively, the cylinder  21  and the middle side plate  25   c  may be produced separately and connected by means of press fit. Moreover, in this embodiment, the axial length of the first rotor  22   a  and the axial length of the second rotor  22   b  are equal to each other, and the first compression chamber Va and the second compression chamber Vb are partitioned in a manner that the maximum capacity is approximately the same therebetween. 
     The shaft  24  is an approximately cylindrical component which rotatably supports the cylinder  21  (specifically, each side plate  25   a ,  25   b ,  25   c  fixed to the cylinder  21 ), the first rotor  22   a , and the second rotor  22   b.    
     An eccentric part  24   c  is defined at the central area of the shaft  24  in the axial direction, and the outer diameter of the eccentric part  24   c  is smaller than that of the end portion adjacent to the sub housing  12 . The central axis of the eccentric part  24   c  is an eccentric axis C 2  eccentric to the central axis C 1  of the cylinder  21 . Furthermore, the first and second rotors  22   a  and  22   b  are rotatably supported by the eccentric part  24   c  through non-illustrated bearing mechanism. 
     The first and second compression mechanism parts  20   a  and  20   b  of this embodiment are arranged in the central axial direction of the cylinder  21 . For this reason, as shown in  FIG. 1  and  FIG. 4 , the first rotor  22   a  and the second rotor  22   b  are arranged in the central axial direction of the cylinder  21 . Furthermore, the first and second rotors  22   a  and  22   b  rotate about the common eccentric axis C 2  eccentric to the central axis C 1  of the cylinder  21 . That is, in this embodiment, the eccentric axis of the first rotor  22   a  and the eccentric axis of the second rotor  22   b  are arranged on the same axis. 
     As shown in  FIG. 1 , a shaft side inlet passage  24   d  is defined in the shaft  24 , and is communicated to the housing side inlet passage  13   a , for leading the low-pressure refrigerant flowed from the outside toward the first and second compression chambers Va and Vb. Plural (four in this embodiment) first shaft side exit holes  240   a  and plural (four in this embodiment) second shaft side exit holes  240   b  are opened in the outer circumference surface of the shaft  24  to discharge the low-pressure refrigerant from the shaft side inlet passage  24   d.    
     As shown in  FIG. 1  and  FIG. 4 , a first shaft side concave portion  241   a  and a second shaft side concave portion  241   b  are formed on the outer circumference surface of the shaft  24 , and are recessed inward from the outer circumference surface of the shaft  24 . The first and second shaft side exit holes  240   a  and  240   b  are respectively communicated to the formation parts of the first and second shaft side concave portions  241   a  and  241   b . For this reason, the first and second shaft side exit holes  240   a  and  240   b  are communicated to circular first and second shaft side communication spaces  242   a  and  242   b  defined in the first and second shaft side concave portions  241   a  and  241   b , respectively. 
     The first rotor  22   a  is a cylindrical component arranged inside the cylinder  21  and extending in the central axial direction of the cylinder  21 . As shown in  FIG. 1 , the length of the first rotor  22   a  in the axial direction is approximately the same as the length of a portion of the shaft  24  and the cylinder  21  which defines the first compression mechanism part  20   a  in the axial direction. 
     Furthermore, the outer diameter of the first rotor  22   a  is smaller than the inside diameter of the cylindrical space formed inside of the cylinder  21 . In detail, as shown in  FIG. 2  and  FIG. 3 , the outer diameter of the first rotor  22   a  is set such that the outer circumference surface of the first rotor  22   a  and the inner circumference surface of the cylinder  21  are in contact with each other at one junction point C 3  when seen from the axial direction of the eccentric axis C 2 . 
     A motion transmitting mechanism is arranged between the first rotor  22   a  and the middle side plate  25   c  and between the first rotor  22   a  and the first side plate  25   a . The motion transmitting mechanism transmits the rotation power from the cylinder  21  (specifically, the middle side plate  25   c  and the first side plate  25   a  which rotate with the cylinder  21 ) to the first rotor  22   a , such that the first rotor  22   a  has synchronous rotation with the cylinder  21 . 
     The motion transmitting mechanism, which is arranged between the first rotor  22   a  and the middle side plate  25   c , is explained. As shown in  FIG. 2 , the motion transmitting mechanism includes plural (four in this embodiment) first hole parts  221   a  having round form and formed on a surface of the first rotor  22   a  adjacent to the middle side plate  25   c , and plural (four in this embodiment) drive pins  251   c  projected from the middle side plate  25   c  toward the first rotor  22   a  in the central axial direction. 
     The drive pin  251   c  has a diameter smaller than that of the first hole part  221   a , and is projected toward the rotor  22  in the axial direction and inserted in the first hole part  221   a . The drive pin  251   c  and the first hole part  221   a  define a mechanism equivalent to the so-called pin-hole type rotation prevention mechanism. The motion transmitting mechanism located between the first rotor  22   a  and the first side plate  25   a  has the similar structure as the above. 
     When the cylinder  21  rotates about the central axis C 1 , according to the motion transmitting mechanism of this embodiment, the relative position (relative distance) between the drive pin  251   c  and the eccentric part  24   c  of the shaft  24  changes. The side wall surface of the first hole part  221   a  of the first rotor  22   a  receives a load from the drive pin  251   c  in the rotational direction, which is caused by the change in the relative position (relative distance). As a result, the first rotor  22   a  rotates about the eccentric axis C 2 , synchronizing with rotation of the cylinder  21 . 
     The motion transmitting mechanism of this embodiment transmits the power to the rotor  22  sequentially through the drive pins  251   c  and the first hole parts  221   a . Therefore, it is desirable that the drive pins  251   c  and the first hole parts  221   a  are arranged around the eccentric axis C 2  at equal angle interval. Furthermore, a metal ring component  223   a  is inserted in each of the first hole parts  221   a  to restrict wear of the outer circumference surface to which the drive pin  251   c  contacts. 
     Moreover, as shown in a dashed line of  FIG. 1 , a first oil passage  225   a  is defined inside the first rotor  22  to extend in the axial direction of the eccentric axis C 2 . The first oil passage  225   a  penetrates the first rotor  22  from one end to the other end in the axial direction. 
     The first oil passage  225   a  is a lubricating oil passage for the lubricating oil supplied through a first oil return passage  11   b  defined in the bottom of the main housing  11  and an oil passage  252   a  defined by a clearance between the shaft  24  and the boss part of the first side plate  25   a . The first oil return passage  11   b  is a lubricating oil passage which introduces lubricating oil toward the first oil passage  225   a  from the lower side of the interior space of the housing  10 . 
     Furthermore, the first hole parts  221   a  of the motion transmitting mechanism between the first rotor  22   a  and the middle side plate  25   c  and between the first rotor  22   a  and the first side plate  25   a  are formed by ends of the first oil passage  225   a  in the axial direction. 
     In other words, at least one first hole part of the motion transmitting mechanism between the first rotor  22   a  and the first side plate  25   a , and at least one first hole part  221   a  of the motion transmitting mechanism between the first rotor  22   a  and the middle side plate  25   c  communicate mutually through the first oil passage  225   a.    
     Moreover, as shown in  FIG. 2  and  FIG. 3 , a first groove portion (a first slit part)  222   a  is formed in the outer circumference surface of the first rotor  22   a , and is recessed radially inward and extends within the all area in the axial direction. The first vane  23   a  to be mentioned later is slidably inserted in the first groove portion  222   a.    
     When seen from the axial direction of the eccentric axis C 2 , a surface of the first groove portion  222   a  on which the first vane  23   a  slides (the friction surface with the first vane  23   a ) is inclined relative to the radial direction of the first rotor  22   a . In detail, the surface of the first groove portion  222   a  on which the first vane  23   a  slides is inclined from the inner circumference side to the outer circumference side in the rotational direction. For this reason, the first vane  23   a  inserted in the first groove portion  222   a  is also displaced in the direction inclined to the radial direction of the first rotor  22   a.    
     As shown in  FIG. 3 , a first rotor side inlet passage  224   a  is formed inside of the first rotor  22   a , at the central part in the axial direction, similarly to the first groove portion  222   a , and extends in the inclined manner relative to the radial direction. The inner circumference side (adjacent to the first shaft side communication space  242   a ) and the outer circumference side (adjacent to the first compression chamber Va) of the first rotor  22   a  are communicated with each other by the first rotor side inlet passage  224   a . Thereby, the refrigerant flowing in the shaft side inlet passage  24   d  from the exterior is led toward the first rotor side inlet passage  224   a.    
     Furthermore, as shown in  FIG. 3 , the exit of the first rotor side inlet passage  224   a  is opened in the outer circumference surface of the first rotor  22   a  on the rear side of the first groove portion  222   a  in the rotational direction. Moreover, the first rotor side inlet passage  224   a  and the first groove portion  222   a  are separated from each other, and formed not to communicate with each other. 
     The first vane  23   a  is a tabular partition component that defines the first compression chamber Va formed between the outer circumference surface of the first rotor  22   a  and the inner circumference surface of the cylinder  21 . The axial length of the first vane  23   a  is approximately the same as the axial length of the first rotor  22   a . Furthermore, the outer circumference side tip part of the first vane  23   a  is slidable on the inner circumference surface of the cylinder  21 . 
     Therefore, in the first compression mechanism part  20   a  of this embodiment, the first compression chamber Va is formed of a space surrounded by the inner wall surface of the cylinder  21 , the outer circumference surface of the first rotor  22   a , the board surface of the first vane  23   a , the first side plate  25   a , and the middle side plate  25   c . That is, the first vane  23   a  defines the first compression chamber Va formed between the inner circumference surface of the cylinder  21  and the outer circumference surface of the first rotor  22   a.    
     Moreover, the first side plate  25   a  has a first discharge hole  251   a  to discharge the refrigerant compressed by the first compression chamber Va to the interior space of the housing  10 . Furthermore, a first discharge valve such as a reed valve is arranged in the first side plate  25   a  to restrict the refrigerant flowing out of the first discharge hole  251   a  into the interior space of the housing  10  from flowing backwards to the first compression chamber Va through the first discharge hole  251   a.    
     Next, the second compression mechanism part  20  is explained. The fundamental configuration of the second compression mechanism part  20   b  is the same as that of the first compression mechanism part  20   a . As shown in  FIG. 1 , the second rotor  22   b  includes a cylindrical component with a dimension approximately equal to the axial length of a portion of the shaft  24  and the cylinder  21  which defines the second compression mechanism part  20   b.    
     Furthermore, since the eccentric axis C 2  of the second rotor  22   b  and the eccentric axis C 2  of the first rotor  22   a  are arranged on the same axis, when seen from the axial direction of the eccentric axis C 2 , the outer circumference surface of the second rotor  22   b  and the inner circumference surface of the cylinder  21  are in contact with each other, like the first rotor  22   a , at the junction point C 3  shown in  FIG. 2  and  FIG. 3 . 
     A motion transmitting mechanism is disposed between the second rotor  22   b  and the middle side plate  25   c  and between the second rotor  22   b  and the first side plate  25   a , similarly to the motion transmitting mechanism which transmits the rotation power to the first rotor  22   a . The second rotor  22   b  has plural second round hole parts into which the plural drive pins  251   c  are inserted. A ring component is inserted also in this second hole part, similarly to the first hole part  221   a.    
     Furthermore, the drive pin  251   c  projected from the middle side plate  25   c  toward the second rotor  22   b  is formed by the same component as the drive pin  251   c  projected from the middle side plate  25   c  toward the first rotor  22   b . That is, the drive pin  251   c  fixed to the middle side plate  25   c  is projected toward both of the first rotor  22   a  and the second rotor  22   b  in the central axial direction. 
     As shown in  FIG. 1 , a second oil passage  225   b  is formed in the second rotor  22   b , similarly to the first oil passage  225   a  of the first rotor  22   a , to extend in the axial direction of the eccentric axis C 2 , and penetrates the second rotor  22   b  from one end to the other end in the axial direction. 
     The second oil passage  225   b  is a lubricating oil passage for the lubricating oil supplied through a second oil return passage  12   b  defined in the sub housing  12  and an oil passage  252   b  formed by a clearance between the shaft  24  and the boss part of the second side plate  25   b . The second oil return passage  12   b  is a lubricating oil passage which introduces the lubricating oil collected on the lower side of the interior space of the housing  10  toward the second oil passage  225   b.    
     Furthermore, like the first oil passage  225   a , the both ends of the second oil passage  225   b  in the axial direction form the second hole parts of the motion transmitting mechanism. 
     Moreover, as shown in a dashed line of  FIG. 2  and  FIG. 3 , a second groove portion (a second slit part)  222   b  is formed in the outer circumference surface of the second rotor  22   b , and is recessed radially inward and extends in all the area in the axial direction. The second vane  23   b  is slidably inserted in the second groove portion  222   b , like the first vane  23   a  of the first groove portion  222   a.    
     As shown in a dashed line of  FIG. 3 , a second rotor side inlet passage  224   b  is defined inside the second rotor  22   b  at the central part in the axial direction, and extends in the inclined manner relative to the radial direction, like the second groove portion  222   b , to communicate the inner circumference side and the outer circumference side (adjacent to the second compression chamber Vb) of the second rotor  22   b  with each other. 
     Therefore, in the second compression mechanism part  20   b  of this embodiment, the second compression chamber Vb is formed of a space surrounded by the inner wall surface of the cylinder  21 , the outer circumference surface of the second rotor  22   b , the board surface of the second vane  23   b , the second side plate  25   b , and the middle side plate  25   c . That is, the second vane  23   b  defines the second compression chamber Vb formed between the inner circumference surface of the cylinder  21  and the outer circumference surface of the second rotor  22   b.    
     Moreover, a second discharge hole  251   b  is formed in the second side plate  25   b  to discharge the refrigerant compressed by the second compression chamber Vb to the interior space of the housing  10 . Furthermore, a second discharge valve such as a reed valve is arranged in the second side plate  25   b  to restrict the refrigerant flowing out of the second discharge hole  251   b  into the interior space of the housing  10  from flowing backwards to the second compression chamber Vb through the second discharge hole  251   b.    
     Furthermore, as shown in a dashed line of  FIG. 2  and  FIG. 3 , in the second compression mechanism part  20   b  of this embodiment, the second vane  23   b , the second rotor side inlet passage  224   b , the second discharge hole  251   b  of the second side plate  25   b , and the like are arranged at positions shifted by about 180 degrees in the phase, relative to the first vane  23   a , the first rotor side inlet passage  224   a , the first discharge hole  251   a  of the first side plate  25   a , and the like of the first compression mechanism part  20   a.    
     Next, the operations of the compressor  1  of this embodiment are explained with reference to  FIG. 5 .  FIG. 5  is a diagram showing sequential change of the first compression chamber Va in response to the rotation of the cylinder  21 , in order to explain the operation state of the compressor  1 . 
     In the sectional views of  FIG. 5 , in response to change in the rotation angle θ of the cylinder  21 , the solid line shows positions of the first rotor side inlet passage  224   a  and the first vane  23   a , similarly to  FIG. 3 . Moreover, in  FIG. 5 , the dashed line shows positions of the second rotor side inlet passage  224   b  and the second vane  23   b  in response to change in the rotation angle θ. Furthermore, in  FIG. 5 , the reference number is given only to the sectional view in which the rotation angle θ of the cylinder  21  is 0 degree, for clarification in the illustration. 
     First, when the rotation angle θ is 0 degree, the outer circumference side tip part of the first vane  23   a  overlaps with the junction point C 3 . In this state, the first compression chamber Va having the maximum capacity is formed on the front side of the first vane  23   a  in the rotational direction, and the first compression chamber Va having the minimum capacity (that is, capacity is zero) of an admission stroke is formed on the rear side of the first vane  23   a  in the rotational direction. 
     Here, the first compression chamber Va of an admission stroke means the first compression chamber Va in a stroke to increase the capacity, and the first compression chamber Va of a compression stroke means the first compression chamber Va in a process to reduce the capacity. 
     In response to an increase in the rotation angle θ from 0 degree, as shown from 45 degrees to 315 degrees in the rotation angle θ of  FIG. 5 , the cylinder  21 , the first rotor  22   a , and the first vane  23   a  are displaced, such that the capacity of the first compression chamber Va of an admission stroke formed on the rear side of the first vane  23   a  in the rotational direction increases. 
     Thereby, the low-pressure refrigerant drawn from the inlet port  12   a  of the sub housing  12  flows in order of the housing side inlet passage  13   a , the first shaft side exit hole  240   a  of the shaft side inlet passages  24   d , and the first rotor side inlet passage  224   a  into the first compression chamber Va of an admission stroke. 
     At this time, since the centrifugal force acts on the first vane  23   a  in response to the rotation of the rotor  22 , the outer circumference side tip part of the first vane  23   a  is forced onto the inner circumference surface of the cylinder  21 . Thereby, the first vane  23   a  divides the first compression chamber Va of an admission stroke and the first compression chamber Va of a compression stroke from each other. 
     When the rotation angle θ becomes 360 degrees (namely, when the rotation angle θ returns to 0 degree), the first compression chamber Va of an admission stroke has the maximum capacity. Furthermore, when the rotation angle θ increases from 360 degrees, the communication between the first compression chamber Va of an admission stroke where the capacity is increased when the rotation angle θ increases from 0 degree to 360 degrees and the first rotor side inlet passage  224   a  is intercepted. Thereby, the first compression chamber Va of a compression stroke is formed on the front side of the first vane  23   a  in the rotational direction. 
     Furthermore, while the rotation angle θ increases from 360 degrees, as shown in point hatching of  FIG. 5  where the rotation angle θ increases from 405 degrees to 675 degrees, the capacity of the first compression chamber Va of a compression stroke formed on the front side of the first vane  23   a  in the rotational direction reduces. 
     Thereby, the refrigerant pressure in the first compression chamber Va of a compression stroke rises. When the refrigerant pressure in the first compression chamber Va exceeds a valve open pressure of the first discharge valve (namely, the maximum pressure of the first compression chamber Va) determined based on the refrigerant pressure in the interior space of the housing  10 , the refrigerant in the first compression chamber Va is discharged to the interior space of the housing  10  through the first discharge hole  251   a.    
     The change in the first compression chamber Va is explained, in response to the change in the rotation angle θ from 0 degree to 720 degrees, for clarifying the operation mode of the first compression mechanism part  20   a . However, in actual, an admission stroke of the refrigerant explained when the rotation angle θ changes from 0 degree to 360 degrees, and a compression stroke of the refrigerant explained when the rotation angle θ changes from 360 degrees to 720 degrees are simultaneously carried out while the cylinder  21  has one rotation. 
     Moreover, the second compression mechanism part  20   b  operates similarly, and compression and admission of refrigerant are performed. At this time, in the second compression mechanism part  20   b , the second vane  23   b  is arranged at the position shifted by 180 degrees in phase relative to the first vane  23   a  of the first compression mechanism part  20   a . Therefore, in the second compression chamber Vb of a compression stroke, compression and admission of refrigerant are performed at the rotation angle shifted from the first compression chamber Va by 180 degrees in phase. 
     For this reason, in this embodiment, the rotation angle θ of the cylinder  21  where the refrigerant pressure in the first compression chamber Va reaches the maximum pressure, and the rotation angle θ of the cylinder  21  where the refrigerant pressure in the second compression chamber Vb reaches the maximum pressure are shifted from each other by 180 degrees. 
     When the refrigerant pressure in the second compression chamber Vb of a compression stroke rises, and when the refrigerant pressure in the second compression chamber Vb exceeds a valve open pressure of the second discharge valve arranged at the second side plate  25   b  (namely, the maximum pressure of the second compression chamber Vb), the refrigerant in the second compression chamber Vb is discharged through the second discharge hole  251   b  to the interior space of the housing  10 . The refrigerant discharged from the second compression mechanism part  20   b  to the interior space of the housing  10  joins the refrigerant discharged from the first compression mechanism part  20   a.    
     The refrigerant mixed of the high-pressure gas phase refrigerant discharged from the first compression mechanism part  20   a  and the high-pressure gas phase refrigerant discharged from the second compression mechanism part  20   b  reduces the flow velocity in the interior space of the housing  10 . Thereby, the lubricating oil discharged from the first and second discharge holes  251   a  and  251   b  with the high-pressure gas phase refrigerant is separated from the mixed refrigerant, due to the gravity, by falling downward. 
     The mixed refrigerant from which the lubricating oil is separated is discharged from the discharge port  11   a  of the housing  10 . Meanwhile, the lubricating oil separated from the refrigerant can be stored on the lower side of the interior space of the housing  10 . The lubricating oil stored on the lower side of the interior space of the housing  10  flows into the first and second oil passages  225   a  and  225   b  through the first and second oil return passages  11   b  and  12   b , so as to be supplied to each sliding part of the shaft  24 , the first and second rotors  22   a  and  22   b , and the side plates  25   a - 25   c.    
     Thus, the compressor  1  of this embodiment draws, compresses, and discharges the refrigerant (fluid) in the refrigeration cycle apparatus. Moreover, since the compression mechanism part  20  is arranged in the inner circumference side of the electric motor part  30 , the compressor  1  of this embodiment can be downsized as the whole. 
     Furthermore, since the compressor  1  of this embodiment has the first rotor  22   a  (the first compression mechanism part  20   a ) and the second rotor  22   b  (the second compression mechanism part  20   b ), the first compression chamber Va and the second compression chamber Vb can be formed. Therefore, the total discharge capacity of the first compression chamber Va and the second compression chamber Vb can be easily increased in accordance with the system (the refrigeration cycle apparatus in this embodiment) to which the compressor is applied. 
     Meanwhile, since the first rotor  22   a  and the second rotor  22   b  are arranged along the central axial direction of the cylinder  21 , the outer diameter of the cylinder  21  is not increased to increase the sum of the discharge capacity. Therefore, the outer diameter of the stator  31  of the electric motor part  30  is restricted from increasing, and the outer diameter of the main housing  11  which accommodates the stator  31  is restricted from increasing. 
     As a result, according to the compressor  1  of this embodiment, the capacity of the compression chamber (Va, Vb) can be increased without causing enlargement in the radial direction. 
     Moreover, since the eccentric axis C 2  of the first rotor  22   a  and the eccentric axis C 2  of the second rotor  22   b  are arranged on the same axis in the compressor  1  of this embodiment, it is not necessary to form portions corresponding to eccentric axes different from each other in the shaft  24 . Therefore, the shaft  24  can be formed easily. 
     Moreover, in the compressor  1  of this embodiment, the maximum capacity is approximately the same between the first compression chamber Va and the second compression chamber Vb. Furthermore, the rotation angle θ of the cylinder  21  where the refrigerant in the first compression chamber Va reaches the maximum pressure, and the rotation angle θ of the cylinder  21  where the refrigerant in the second compression chamber Vb reaches the maximum pressure are shifted from each other by 180 degrees. 
     Thereby, as shown in  FIG. 6 , the torque fluctuations caused by increase in the capacity of the compression chamber can be restricted from increasing. Therefore, the noise and vibration can be effectively restricted from increasing as the whole compressor. 
       FIG. 6  is a graph comparing the total torque fluctuation of the compressor  1  of this embodiment with torque fluctuation of a rotating cylinder type compressor (compressor with a single cylinder) having a single compression mechanism part similar to the first compression mechanism part  20   a . In addition, the total torque fluctuation is the sum of the torque fluctuations produced by the pressure fluctuation of the refrigerant in the first compression chamber Va of the first compression mechanism part  20   a  and the torque fluctuations produced by the pressure fluctuation of the refrigerant in the second compression chamber Vb of the second compression mechanism part  20   b.    
     Furthermore, the discharge capacity of the compressor with the single cylinder shown in  FIG. 6  is in agreement with the total discharge capacity of the first compression chamber Va and the second compression chamber Vb of the compressor  1  of this embodiment. Furthermore, the suction refrigerant pressure and the discharge refrigerant pressure of the compressor with the single cylinder shown in  FIG. 6  are respectively set similar with the suction refrigerant pressure and the discharge refrigerant pressure of the compressor  1  of this embodiment. 
     Moreover, since the first and second oil passages  225   a  and  225   b  are formed in the first and second rotors  22   a  and  22   b  in the compressor  1  of this embodiment, each sliding part of the shaft  24 , the first and second rotors  22   a  and  22   b , and the side plates  25   a - 25   c  can be lubricated. As a result, the durability of the compressor  1  can be raised as a whole. 
     The lubricating oil can be effectively introduced into the sliding part between the first and second rotors  22   a ,  22   b  and the middle side plate  25   c , positioned at the central part of the cylinder  21  in the central axial direction, due to the first and second oil passages  225   a  and  225   b.    
     Since a structure similar to the so-called pin-hole type rotation prevention mechanism is adopted as a motion transmitting mechanism in the compressor  1  of this embodiment, the motion transmitting mechanism can be realized with simple structure. Furthermore, since the ring component  223   a  is inserted in the hole part of the motion transmitting mechanism, the wear resistance of the hole part can be raised. As a result, the durability can be raised as the whole compressor  1 . 
     In addition, the first and second hole parts  221   a  are defined at the axial ends of the first and second oil passages  225   a  and  225   b . Therefore, a space for arranging the motion transmitting mechanism can be reduced. Thus, the compressor  1  can be further downsized as the whole. 
     According to the compressor  1  of this embodiment, the inlet passage introducing the refrigerant drawn from the outside to the first and second compression chambers Va and Va is defined by the shaft side inlet passage  24   d , the first and second rotor side inlet passages  224   a  and  224   b , and the like. Therefore, the passage structure and the sealing structure of the inlet passage are restricted from becoming complicated, compared with a case where a part of the inlet passage is formed in the first and second side plates  25   a  and  25   b  which rotate with the cylinder  21 . 
     Furthermore, since the first and second discharge holes  251   a  and  251   b  are respectively formed in the first and second side plates  25   a  and  25   b , the first and second compression mechanism parts  20   a  and  20   b  can be easily connected with each other in parallel to a flow of the refrigerant, inside the housing  10 . 
     Second Embodiment 
     As shown in  FIG. 7 , in the present embodiment, the compression mechanism part  20  is modified relative to the first embodiment. In addition,  FIG. 7  is a sectional view corresponding to  FIG. 3  which is explained in the first embodiment, and shows a sectional view of the first compression mechanism part  20   a  perpendicular to the axial direction. In  FIG. 7 , the same or equivalent portion as the first embodiment is attached with the same reference number. This is the same also in  FIG. 8  to be explained below. 
     More specifically, a first hinge part  231   a  is formed at the outer circumference side end portion of the first vane  23   a , in the first compression mechanism part  20   a  of this embodiment. The first hinge part  231   a  is supported by a groove portion formed in the inner circumference surface of the cylinder  21 , and is swingable in the circumferential direction. For this reason, the vane  23  does not separate from the cylinder  21 , and the inner circumference side of the first vane  23   a  is displaced inside of the first groove portion  222   a  in the sliding manner. 
     Furthermore, a circular part with a diameter equivalent to the width dimension of the first groove portion  222   a  is formed at the inner circumference side end portion of the first vane  23   a . Therefore, when the first vane  23   a  swings in response to rotation of the cylinder  21 , the inner circumference side end portion of the first vane  23   a  is securely made in contact with the inner wall surface of the first groove portion  222   a , namely, the sealing property between the inner circumference side end portion of the first vane  23   a  and the inner wall surface of the first groove portion  222   a  is raised. 
     The fundamental configuration of the second compression mechanism part  20   b  is the same as that of the first compression mechanism part  20   a . Therefore, as shown in a dashed line of  FIG. 7 , the outer circumference side end portion of the second vane  23   b  is also swingably supported by the cylinder. 
     The other configurations and operations are the same as those of the first embodiment. Therefore, when the compressor  1  of this embodiment is operated, the compressor operates similarly to the first embodiment. Specifically, refrigerant (fluid) can be drawn, compressed and discharged in the refrigeration cycle apparatus. Furthermore, like the first embodiment, the capacity of the compression chamber (Va, Vb) can be increased without causing enlargement in the radial direction, and noise and vibration can be restricted from increasing as the whole compressor. 
     Third Embodiment 
     As shown in  FIG. 8 , the compression mechanism part  20  is modified in this embodiment, relative to the second embodiment. More specifically, in the first compression mechanism part  20   a  of this embodiment, the inner circumference side of the first vane  23   a  on the radially inner side of the first hinge part  231   a  is formed into a plate shape. 
     Furthermore, a first shoe  232   a  is arranged in the first groove portion  222   a , and has a cross-sectional form (approximately semi-circle shape) in which a part of the circle is cut off, when seen from the axial direction of the central axis C 1 . The first vane  23   a  is interposed between the first shoes  232   a . The length of the first shoe  232   a  in the axial direction is approximately the same as the first rotor  22   a  and the first vane  23   a . The fundamental configuration of the second compression mechanism part  20   b  is the same as that of the first compression mechanism part  20   a.    
     The other configuration and operations are the same as those of the second embodiment. Therefore, when the compressor  1  of this embodiment is operated, the compressor operates like the second embodiment. Specifically, in the refrigeration cycle apparatus, the refrigerant (fluid) can be drawn, compressed and discharged. Furthermore, like the first embodiment, the capacity of the compression chamber (Va, Vb) can be increased without causing enlargement in the radial direction. The noise and vibration can be restricted from increasing as the whole compressor. 
     Furthermore, in the compressor  1  of this embodiment, the shoe  232   a  effectively raises the sealing property between the first and second vane  23   a ,  23   b  and the inner wall surface of the first and second groove portion  222   a ,  222   b . Thereby, the compression efficiency of the compressor  1  can be raised. 
     Other Embodiment 
     The contents of the present disclosure can variously be modified within the range not deviated from the scope of present disclosure without being limited to the above-mentioned embodiments. 
     In the above-mentioned embodiments, the rotating cylinder type compressor  1  is applied to the refrigeration cycle of the air-conditioner for a vehicle, but the rotating cylinder type compressor  1  is not limited to be applied to this. That is, the rotating cylinder type compressor  1  may be widely applied to a compressor which compresses various fluid. 
     In the above-mentioned embodiments, a structure similar to a pin-hole type rotation prevention mechanism is adopted as the power transmitting device of the rotating cylinder type compressor  1 , but is not limited to this. For example, a structure similar to an Oldham ring type rotation prevention mechanism may be adopted. 
     In the above-mentioned embodiments, the stator of the electric motor part  30  is arranged at the outer circumference side of the cylinder  21  formed integrally with the rotor, but the electric motor part  30  is not limited to this. For example, the electric motor part and the cylinder  21  may be arranged side by side in the extending direction of the central axis C 1  of the cylinder  21 , and the electric motor part and the cylinder  21  may be connected with each other. Moreover, the rotation power of the electric motor part may be transmitted to the cylinder  21  through a belt, without arranging the rotation center of the electric motor part and the central axis C 1  of the cylinder  21  on the same axis.