Patent Publication Number: US-2021164471-A1

Title: Compressor

Description:
TECHNICAL FIELD 
     The present invention relates to a compressor. 
     BACKGROUND ART 
     Patent Document 1 describes a compressor including a rotary shaft, rotors rotated with rotation of the rotary shaft, a vane moving in the axial direction of the rotary shaft with rotation of the rotors, and compression chambers. In this compressor, fluid is compressed in the compression chamber by rotating the rotors. 
     This document describes, as a third embodiment, a rotor surface formed by a curved surface in which the position of a straight line extending in the radial direction continuously becomes low from an initial angle to a first angular position of the rotor, and continuously becomes high from the first angular position to the initial angle, and a vane including an end contacting the rotor surface. 
     In the above-described configuration, the vane is easily oscillated in the circumferential direction of the rotor about the part at which the rotor surface contacts the end of the vane and that extends in the radial direction. 
     PRIOR ART DOCUMENT 
     Patent Document 
     Patent Document 1: Japanese Laid-Open Patent Publication No. 51-97006 
     SUMMARY OF THE INVENTION 
     Problems that the Invention is to Solve 
     An object of the present invention is to provide a compressor that can suppress the oscillation of a vane in the circumferential direction of a rotor. 
     Means for Solving the Problems 
     To achieve the foregoing objective and in accordance with a first aspect, a compressor is provided that includes a rotary shaft, a rotor including a rotor surface formed into a ring-shape, and rotated with rotation of the rotary shaft, a cylindrical portion including an inner circumferential surface opposed to an outer circumferential surface of the rotor in a radial direction of the rotary shaft, and housing the rotor, a wall portion including a wall surface opposed to the rotor surface in an axial direction of the rotary shaft, a vane inserted into a vane groove formed in the wall portion, and moved in the axial direction with rotation of the rotor, and a compression chamber defined by the rotor surface, the wall surface, and the inner circumferential surface of the cylindrical portion. A volume change of the compression chamber is caused by the vane with rotation of the rotor such that suction and compression of fluid are performed. The vane includes a vane end that is an end in the axial direction and contacts the rotor surface. The vane end is curved so as to be convex toward the rotor surface and extends in a direction perpendicular to the axial direction. The rotor surface includes a curving surface curved in the axial direction. The curving surface is curved so as to be displaced in the axial direction in accordance with its angular position. The curving surface includes a concave surface curved in the axial direction so as to be concave toward the wall surface, and a convex surface curved in the axial direction so as to be convex toward the wall surface. The concave surface includes a concave surface radially inner end and a concave surface radially outer end as opposite ends in the radial direction. In the concave surface, a radius of curvature of the concave surface radially inner end in the axial direction is smaller than a radius of curvature of the concave surface radially outer end. The convex surface includes a convex surface radially inner end and a convex surface radially outer end as opposite ends in the radial direction. In the convex surface, a radius of curvature of the convex surface radially inner end in the axial direction is smaller than a radius of curvature of the convex surface radially outer end. 
     To achieve the foregoing objective and in accordance with a second aspect, a compressor is provided that includes a rotary shaft, a rotor including a rotor surface formed into a ring-shape and rotated with rotation of the rotary shaft, a cylindrical portion including an inner circumferential surface opposed to an outer circumferential surface of the rotor in a radial direction of the rotary shaft, and housing the rotor, a wall portion including a wall surface opposed to the rotor surface in an axial direction of the rotary shaft, a vane that is inserted into a vane groove formed in the wall portion, and is moved in the axial direction with rotation of the rotor, and a compression chamber defined by the rotor surface, the wall surface, and the inner circumferential surface of the cylindrical portion. Volume change of the compression chamber is caused by the vane with rotation of the rotor such that suction and compression of fluid are performed. The vane includes a vane end that is an end in the axial direction and contacts the rotor surface. The vane end is curved so as to be convex toward the rotor surface and extends in a direction perpendicular to the axial direction. The rotor surface includes a curving surface curved in the axial direction. The curving surface is curved so as to be displaced in the axial direction in accordance with its angular position. The curving surface includes a part in which a radius of curvature with respect to the axial direction differs in accordance with a position in the radial direction such that at least a part of a contact line between the curving surface and the vane end is curved in a circumferential direction of the rotor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view showing an outline of a compressor. 
         FIG. 2  is an exploded perspective view of a main configuration. 
         FIG. 3  is an exploded perspective view of the main configuration seen from the opposite side from  FIG. 2 . 
         FIG. 4  is a partial enlarged view of  FIG. 1 . 
         FIG. 5  is a cross-sectional view taken along line  5 - 5  in  FIG. 4  in a non-communicating state. 
         FIG. 6  is a cross-sectional view taken along line  5 - 5  in  FIG. 4  in a communicating state. 
         FIG. 7  is a cross-sectional view schematically showing the contacting manner between the vane and the curving surfaces. 
         FIG. 8  is a graph showing the displacement in the axial direction in accordance with the angular position on the rotor surface. 
         FIG. 9  is a front view of the front rotor. 
         FIG. 10  is a front view of the rear rotor. 
         FIG. 11  is a cross-sectional view showing the peripheral structure of the rotors and the vane in a case where they are cut near an inflection point. 
         FIG. 12  is a schematic diagram showing a front contact line seen from the axial direction. 
         FIG. 13  is a schematic diagram showing a rear contact line seen from the axial direction. 
         FIG. 14A  is a cross-sectional view showing the rotors and their surroundings. 
         FIG. 14B  is a cross-sectional view showing the situation of the rotors and the vane in the state of  FIG. 14A . 
         FIG. 15A  is a cross-sectional view showing the rotors and their surroundings. 
         FIG. 15B  is a cross-sectional view showing the situation of the rotors and the vane in the state of  FIG. 15A . 
         FIG. 16  is a graph showing the volume change. 
         FIG. 17  is a schematic diagram showing a modification of a communication mechanism. 
         FIG. 18  is a schematic diagram showing the modification of the communication mechanism. 
         FIG. 19  is a cross-sectional view schematically showing a compressor of a modification. 
         FIG. 20  is a cross-sectional view schematically showing a vane of a modification. 
         FIG. 21  is a partially enlarged view of  FIG. 20 . 
         FIG. 22  is a cross-sectional view schematically showing a vane of a modification. 
     
    
    
     MODES FOR CARRYING OUT THE INVENTION 
     A compressor according to an embodiment will now be described with reference to the drawings. The compressor of the embodiment is mounted on and used in a vehicle. The compressor is used for a vehicle air-conditioner. The fluid to be compressed by the compressor is refrigerant including oil.  FIGS. 1 and 4  show side views of a rotary shaft  12  and the rotors  60  and  80 . 
     As shown in  FIG. 1 , a compressor  10  includes a housing  11 , a rotary shaft  12 , an electric motor  13 , an inverter  14 , a front cylinder  40 , a rear cylinder  50 , a front rotor  60  as a first rotor, and rear rotor  80  as a second rotor. The housing  11  has a generally tubular shape, and includes an inlet  11   a  through which a suction fluid is drawn in from the outside, and an outlet  11   b  from which the fluid is discharged. The rotary shaft  12 , the electric motor  13 , the inverter  14 , the cylinders  40  and  50 , and the rotors  60  and  80  are housed in the housing  11 . 
     The housing  11  includes a front housing member  21 , a rear housing member  22 , and an inverter cover  23 . The front housing member  21  has a tubular shape with a closed end, and is opened toward the rear housing member  22 . The inlet  11   a  is provided at a position between an open end and the bottom in a side wall portion of the front housing member  21 . However, the position of the inlet  11   a  is arbitrary. The rear housing member  22  has a tubular shape with a closed end, and is opened toward the front housing member  21 . The outlet  11   b  is provided in a side surface of the bottom of the rear housing member  22 . The position of the outlet  11   b  is arbitrary. 
     The front housing member  21  and the rear housing member  22  are unitized with their openings opposed to each other. The inverter cover  23  is arranged in the bottom of the front housing member  21 , which is the opposite side from the rear housing member  22 . The inverter cover  23  is fixed to the front housing member  21  with being butted to the bottom of the front housing member  21 . 
     The inverter  14  is housed in the inverter cover  23 . The inverter  14  drives the electric motor  13 . The rotary shaft  12  is supported by the housing  11  in a rotatable state. A ring-shaped first bearing holding part  31  protruding from the bottom is provided in the bottom of the front housing member  21 . A first radial bearing  32 , which rotationally supports a first end of the rotary shaft  12 , is provided inside in the radial direction of the first bearing holding part  31 . A ring-shaped second bearing holding part  33  protruding from the bottom is provided in the bottom of the rear housing member  22 . A second radial bearing  34  is also provided inside the radial direction of the second bearing holding part  33 . The second radial bearing  34  rotationally supports the second end of the rotary shaft  12 , which is on the opposite side from the first end. The axial direction Z of the rotary shaft  12  matches the axial direction of the housing  11 . 
     As shown in  FIGS. 1 to 4 , the front cylinder  40  houses the front rotor  60 . The front cylinder  40  has a tubular shape with a closed end formed to be somewhat smaller than the rear housing member  22 . The front cylinder  40  is opened toward the bottom of the rear housing member  22 . The front cylinder  40  includes a front cylinder bottom  41 , and a front cylinder side wall portion  42  extending from the front cylinder bottom  41  toward the rear housing member  22 . The front cylinder side wall portion  42  is a first cylindrical portion, and enters inside the rear housing member  22 . 
     As shown in  FIGS. 3 and 4 , the front cylinder  40  includes a front cylinder inner circumferential surface  43  as a first inner circumferential surface. The front cylinder inner circumferential surface  43  is a cylindrical surface extending in an axial direction Z. The front cylinder  40  further includes a front large diameter surface  44  whose diameter is larger than the front cylinder inner circumferential surface  43 . The front large diameter surface  44  is provided in a tip part (open end) of the front cylinder side wall portion  42 . A front stepped surface  45  is formed between the front cylinder inner circumferential surface  43  and the front large diameter surface  44 . 
     A bulged part  46  projecting to the radially outside of the rotary shaft  12  is provided in the front cylinder side wall portion  42 . The bulged part  46  is provided in the base end of the front cylinder side wall portion  42 , that is, near the front cylinder bottom  41 . The front housing member  21  and the rear housing member  22  are formed with the bulged part  46  being inserted therebetween. The housings  21  and  22  regulate the position gap in the axial direction Z of the front cylinder  40 . 
     As shown in  FIG. 4 , the front cylinder bottom  41  has a stepped shape in the axial direction Z. The front cylinder bottom  41  includes a first bottom  41   a  arranged on the central side, and a second bottom  41   b  arranged radially outside of the first bottom  41   a,  and closer to the rear housing member  22  than the first bottom  41   a.  A front insertion hole  41   c,  to which the rotary shaft  12  can be inserted, is formed in the first bottom  41   a.  The rotary shaft  12  is inserted into the front insertion hole  41   c.    
     As shown in  FIG. 1 , the front housing member  21  and the front cylinder bottom  41  form a motor chamber A 1 , and house the electric motor  13  in the motor chamber A 1 . The electric motor  13  rotates the rotary shaft  12  in the direction indicated by an arrow M when driving power is supplied from the inverter  14 . The inlet  11   a  is provided in the front housing member  21  that forms the motor chamber A 1 . Therefore, the suction fluid drawn in from the inlet  11   a  is introduced into the motor chamber A 1 . That is, the suction fluid exists in the motor chamber A 1 . 
     Within the compressor  10 , the inverter  14 , the electric motor  13 , and the rotors  60  and  80  are arranged in order in the axial direction Z. The position of each of these parts is arbitrary, and the inverter  14  may be arranged radially outside of the electric motor  13 . 
     As shown in  FIGS. 2 to 4 , the rear cylinder  50  has a tubular shape with a closed end. The rear cylinder  50  is opened toward the bottom of the rear housing member  22 . The rear cylinder  50  is formed to be somewhat smaller than the front cylinder  40 , and is housed in the rear housing member  22 . The rear cylinder  50  is fitted to the front cylinder  40  with the open end of the rear cylinder  50  being butted to the bottom of the rear housing member  22 . 
     The rear cylinder  50  includes an intermediate wall portion  51  forming the bottom of the rear cylinder  50 , and a rear cylinder side wall portion  55  extending in the axial direction Z toward the rear housing member  22  from the intermediate wall portion  51 . The rear cylinder side wall portion  55  and the intermediate wall portion  51  correspond to a second cylindrical portion and a wall portion, respectively. 
     As shown in  FIG. 4 , the intermediate wall portion  51  is arranged so that its wall thickness direction matches the axial direction Z. Therefore, the intermediate wall portion  51  includes a first wall surface  52  and a second wall surface  53  that are perpendicular to the axial direction Z. The intermediate wall portion  51  has a ring shape, and is fitted to the front cylinder  40 . A wall through-hole  54  extending through the axial direction Z is formed in the intermediate wall portion  51 . The wall through-hole  54  is a through-hole having a larger diameter than the rotary shaft  12 . The rotary shaft  12  is inserted into the wall through-hole  54 . 
     The rear cylinder side wall portion  55  has a cylindrical shape extending in the axial direction Z, and includes a rear cylinder inner circumferential surface  56  as a second inner circumferential surface, and a rear cylinder outer circumferential surface  57 . The rear cylinder inner circumferential surface  56  is a cylindrical surface having a smaller diameter than the front cylinder inner circumferential surface  43 . Therefore, the rear cylinder inner circumferential surface  56  is arranged inside in the radial direction of the front cylinder inner circumferential surface  43 . The rear cylinder outer circumferential surface  57  includes several cylindrical surfaces having different diameters, and thus has a stepped shape. The rear cylinder outer circumferential surface  57  includes a first part surface  57   a,  a second part surface  57   b  whose diameter is larger than the first part surface  57   a,  and a third part surface  57   c  whose diameter is larger than the second part surface  57   b.    
     The first part surface  57   a  contacts the front cylinder inner circumferential surface  43 . The second part surface  57   b  contacts the front large diameter surface  44 . The third part surface  57   c  is flush with the outer circumferential surface of the front cylinder side wall portion  42 . A first rear stepped surface  58  formed between the part surfaces  57   a  and  57   b  contacts a front stepped surface  45 , and a second rear stepped surface  59  formed between the part surfaces  57   b  and  57   c  contacts the open end of the front cylinder  40 . 
     As shown in  FIG. 4 , the front cylinder bottom  41 , the front cylinder inner circumferential surface  43 , and the first wall surface  52  form a front housing chamber A 2  that houses the front rotor  60 . The front housing chamber A 2  has a generally cylindrical shape. The inside bottom surface of the rear housing member  22 , the rear cylinder inner circumferential surface  56 , and the second wall surface  53  form a rear housing chamber A 3  that houses the rear rotor  80 . The rear housing chamber A 3  has a generally cylindrical shape. 
     Since the diameter of the rear cylinder inner circumferential surface  56  is smaller than the diameter of the front cylinder inner circumferential surface  43 , the rear housing chamber A 3  is smaller than the front housing chamber A 2 , and the volume of the rear housing chamber A 3  is smaller than the volume of the front housing chamber A 2 . The housing chambers A 2  and A 3  are divided by the intermediate wall portion  51 . The rotors  60  and  80  are arranged to be opposed to each other in the axial direction Z, with the intermediate wall portion  51  being arranged therebetween. 
     The rotary shaft  12  and the rotors  60  and  80  have the same axis. That is, the compressor  10  has the structure for axial center movement, instead of eccentric movement. The circumferential directions of the rotors  60  and  80  match the circumferential direction of the rotary shaft  12 , the radial directions of the rotors  60  and  80  match the radial direction R of the rotary shaft  12 , and the axial directions of the rotors  60  and  80  match the axial direction Z of the rotary shaft  12 . Therefore, the circumferential direction, the radial direction R, and the axial direction Z of the rotary shaft  12  may be properly read as the circumferential direction, the radial direction, and the axial direction of the rotors  60  and  80 . 
     As shown in  FIGS. 2 to 4 , the front rotor  60  has a ring shape, and includes a front through-hole  61  into which the rotary shaft  12  can be inserted. The front through-hole  61  has the same diameter as the rotary shaft  12 . The front rotor  60  is attached to the rotary shaft  12  with the rotary shaft  12  being inserted into the front through-hole  61 . 
     The front rotor  60  rotates with the rotation of the rotary shaft  12 . That is, the front rotor  60  integrally rotates with the rotary shaft  12 . The configuration for the front rotor  60  to integrally rotate with the rotary shaft  12  is arbitrary, and there are, for example, a configuration in which the front rotor  60  is fixed to the rotary shaft  12 , and a configuration in which the front rotor  60  is engaged with the outer circumference of the rotary shaft  12 . 
     A front rotor outer circumferential surface  62 , which is an outer circumferential surface of the front rotor  60 , is a cylindrical surface having the same axis as the rotary shaft  12 . The diameter of the front rotor outer circumferential surface  62  is the same as that of the front cylinder inner circumferential surface  43 . There may be a slight gap between the front rotor outer circumferential surface  62  and the front cylinder inner circumferential surface  43 . 
     The front rotor  60  includes a front rotor surface  70  as a first rotor surface opposed to first wall surface  52 . The front rotor surface  70  has a ring shape. The front rotor surface  70  includes a first front flat surface  71  and a second front flat surface  72  that are perpendicular to the axial direction Z, and a pair of front curving surfaces  73  connecting the front flat surfaces  71  and  72 . The first and second front flat surfaces  71  and  72  correspond to first and second flat surfaces, respectively. 
     As shown in  FIG. 4 , the front flat surfaces  71  and  72  are shifted to the axial direction Z. The second front flat surface  72  is arranged closer to the first wall surface  52  than the first front flat surface  71 . The second front flat surface  72  contacts the first wall surface  52 . Additionally, the front flat surfaces  71  and  72  are separated in the circumferential direction of the front rotor  60 , and are shifted  180  degrees. The front flat surfaces  71  and  72  have sectoral shapes. In the following description, the circumferential direction positions of the rotors  60  and  80  are called the angular positions. 
     Each of the pair of front curving surfaces  73  has a sectoral shape. As shown in  FIG. 3 , the pair of front curving surfaces  73  are opposed to the direction perpendicular to the axial direction Z and the direction along which the front flat surfaces  71  and  72  are arranged. Both of the front curving surfaces  73  have an identical shape. Each of the pair of front curving surfaces  73  connects the front flat surfaces  71  and  72 . One of the pair of front curving surfaces  73  connects one ends in the circumferential directions of the front flat surfaces  71  and  72 , and the other connects the other ends of in the circumferential directions of the front flat surfaces  71  and  72 . 
     As shown in  FIG. 3 , the angular position of the boundary part between the front curving surface  73  and the first front flat surface  71  is a first angular position θ 1 , and the angular position of the boundary part between the front curving surface  73  and the second front flat surface  72  is a second angular position θ 2 . In  FIG. 3 , each of the angular positions θ 1  and θ 2  are indicated by broken lines. However, actually, the boundary parts are continued smoothly. 
     The front curving surface  73  is a curving surface displaced in the axial direction Z in accordance with the angular position of the front rotor  60 . The front curving surface  73  is curved in the axial direction Z so as to be gradually closer to the first wall surface  52  from the first angular position θ 1  to the second angular position θ 2 . Two front curving surfaces  73  are provided on the opposite sides in the circumferential direction of the second front flat surface  72 . The front curving surfaces  73  are each curved so as to be gradually separated from the first wall surface  52  as the front curving surfaces  73  are separated from the second front flat surface  72  in the circumferential direction. The front curving surface  73  is curved in the axial direction Z so as to be gradually closer to or distant from the first wall surface  52  between two arbitrary angular positions that are mutually separated in the circumferential direction, which are not limited to the first angular position θ 1  and the second angular position θ 2 . 
     As shown in  FIGS. 2 to 4 , the rear rotor  80  has a ring shape, and includes a rear through-hole  81  into which the rotary shaft  12  can be inserted. The rear through-hole  81  has the same diameter as the rotary shaft  12 . The rotary shaft  12  is inserted into the rear through-hole  81 , and the rear rotor  80  is engaged with the front rotor  60 . The engagement of the front rotor  60  and the rear rotor  80  will be described later. The rear rotor  80  rotates with the rotation of the rotary shaft  12 . That is, the rear rotor  80  integrally rotates with the rotary shaft  12 . The configuration for the rear rotor  80  to integrally rotate with the rotary shaft  12  is arbitrary, and there are, for example, a configuration in which the rear rotor  80  is fixed to the rotary shaft  12 , and a configuration in which the rear rotor  80  is engaged with the outer circumference of the rotary shaft  12 . 
     The rear rotor  80  is formed to be smaller than the front rotor  60 . The diameter of the rear rotor  80  is smaller than the diameter of the front rotor  60 . A rear rotor outer circumferential surface  82 , which is an outer circumferential surface of the rear rotor  80 , is a cylindrical surface having a smaller diameter than the front rotor outer circumferential surface  62 . The diameter of the rear rotor outer circumferential surface  82  is the same as that of the rear cylinder inner circumferential surface  56 . There may be a slight gap between the rear rotor outer circumferential surface  82  and the rear cylinder inner circumferential surface  56 . 
     As shown in  FIGS. 2 and 4 , the rear rotor  80  includes a rear rotor surface  90  as a second rotor surface opposed to the second wall surface  53 . The rear rotor surface  90  has a ring shape. The rear rotor surface  90  includes a first rear flat surface  91  and a second rear flat surface  92  that are perpendicular to the axial direction Z, and a pair of rear curving surfaces  93  that connect the rear flat surfaces  91  and  92 . The first and second front flat surfaces  91  and  92  correspond to first and second flat surfaces, respectively. 
     As shown in  FIG. 5 , the rear flat surfaces  91  and  92  are shifted in the axial direction Z. The second rear flat surface  92  is arranged closer to the second wall surface  53  than the first rear flat surface  91 . The second rear flat surface  92  contacts the second wall surface  53 . The rear flat surfaces  91  and  92  are separated in the circumferential direction of the rear rotor  80 , and are shifted 180 degrees. The rear flat surfaces  91  and  92  have sectoral shapes. 
     Each of the pair of rear curving surfaces  93  has a sectoral shape. The pair of rear curving surfaces  93  are opposed to the direction perpendicular to the axial direction Z and the direction along which the rear flat surfaces  91  and  92  are arranged. One of the pair of the rear curving surfaces  93  connects one of the ends in the circumferential direction of the rear flat surfaces  91  and  92 , and the other connects the other of the ends in the circumferential direction of the rear flat surfaces  91  and  92 . 
     The rotor surfaces  70  and  90  are arranged to be opposed to each other in the axial direction Z with the intermediate wall portion  51  therebetween. The distance between the rotor surfaces  70  and  90  is constant irrespective of the angular positions and the circumferential direction positions of the rotor surfaces  70  and  90 . As shown in  FIG. 5 , the first front flat surface  71  and the second rear flat surface  92  are opposed to each other in the axial direction Z, and the second front flat surface  72  and the first rear flat surface  91  are opposed to each other in the axial direction Z, respectively. The shift amount in the axial direction Z between the front flat surfaces  71  and  72  is the same as the shift amount between the rear flat surfaces  91  and  92 . The shift amount in the axial direction Z between the front flat surfaces  71  and  72 , and the shift amount between the rear flat surfaces  91  and  92  are called the shift amount L 1 . 
     As shown in  FIG. 4 , the degree of curvature of the front curving surface  73  is the same as the degree of curvature of the rear curving surface  93 . That is, the front curving surface  73  and the rear curving surface  93  are curved in the same direction, so that the separation distance is not changed in accordance with the angular positions. Accordingly, the separation distance between the rotor surfaces  70  and  90  is constant irrespective of the angular positions. The rotor surfaces  70  and  90  have an identical shape except that they have different diameters. Since the shapes of the first rear flat surface  91 , the second rear flat surface  92 , and the rear curving surface  93  are the same as those of the first front flat surface  71 , the second front flat surface  72 , and the front curving surface  73 , a detailed description is omitted. 
     As shown in  FIGS. 2 to 4 , the compressor  10  includes a vane  100 , and a vane groove  110  into which the vane  100  is inserted. The vane  100  contacts the rotors  60  and  80 , and thus moves in the axial direction Z with the rotation of the rotors  60  and  80 . The vane  100  is arranged between the rotors  60  and  80 , that is, between the rotor surfaces  70  and  90 , with the surface of the vane  100  being perpendicular to the circumferential direction of the rotary shaft  12 . The vane  100  has a tabular shape having the thickness in the direction perpendicular to the axial direction Z. 
     The vane  100  has a first vane end  101  and a second vane end  102  as the opposite ends in the axial direction Z. The first vane end  101  contacts the front rotor surface  70 , and the second vane end  102  contacts the rear rotor surface  90 . 
     As shown in  FIG. 2 , the vane groove  110  is formed in the rear cylinder  50 . The vane groove  110  is formed over both of the intermediate wall portion  51  and the rear cylinder side wall portion  55 . The vane groove  110  is a slit extending through the rear cylinder  50  in a radial direction R. The opposite ends of the vane groove  110  in the radial direction R are opened. The vane groove  110  extends through the intermediate wall portion  51 . The end on the front rotor  60  side of the opposite ends of the vane groove  110  in the axial direction Z is opened. The opposite side surfaces of the vane groove  110  are opposed to corresponding surfaces of the opposite surfaces of the vane  100 . The width of the vane groove  110 , that is, the distance between the side surfaces of the vane groove  110 , is the same as or slightly larger than the thickness of the vane  100 . 
     As shown in  FIG. 4 , the vane groove  110  extends in the axial direction Z from the intermediate wall portion  51  to the middle of the rear cylinder side wall portion  55 . The vane groove  110  also exists radially outside of the rear rotor  80 . The length in the axial direction Z of the vane groove  110  is the same as or longer than the length in the axial direction Z of the vane  100 . By inserting the vane  100  into the vane groove  110 , the movement of the vane  100  in the circumferential direction is restricted. In contrast, it is permitted for the vane  100  to move in the axial direction Z along the vane groove  110 . 
     According to this configuration, when the rotors  60  and  80  rotate, the vane  100  moves in the axial direction Z while sliding on the rotor surfaces  70  and  90 . Accordingly, the first vane end  101  of the vane  100  enters into the front housing chamber A 2 , or the second vane end  102  enters into the rear housing chamber A 3 . In contrast, the vane  100  contacts both side surfaces of the vane groove  110 , and thus the movement in the circumferential direction is restricted. Therefore, even if the rotors  60  and  80  are rotated, the vane  100  is not rotated. 
     The vane groove  110  allows the arrangement of the vane  100  over the housing chambers A 2  and A 3  and restricts the rotation of the vane  100 , even if the rotors  60  and  80  are rotated. The movement distance of the vane  100  is the displacement amount (the shift amount L 1 ) in the axial direction Z between the front flat surfaces  71  and  72  (or between the rear flat surfaces  91  and  92 ). During the rotation of the rotors  60  and  80 , the vane  100  continues to contact the rotor surfaces  70  and  90 . That is, the vane  100  does not intermittently contact the rotor surfaces  70  and  90 , and does not periodically repeat separation from and contact with the rotor surfaces  70  and  90 . 
     As shown in  FIG. 4 , a front compression chamber A 4  is formed in the front housing chamber A 2  by the front rotor  60  (the front rotor surface  70 ), the front cylinder inner circumferential surface  43 , and the first wall surface  52 . 
     A rear compression chamber A 5  is formed in the rear housing chamber A 3  by the rear rotor  80  (the rear rotor surface  90 ), the rear cylinder inner circumferential surface  56 , and the second wall surface  53 . In the compression chambers A 4  and A 5 , with the rotation of the rotary shaft  12 , their volumes are periodically changed, and suction/compression of fluid are performed by the vane  100 . That is, the vane  100  produces a volume change in the compression chambers A 4  and A 5 . This point will be described later. 
     Since the front rotor  60  is formed to be larger than the rear rotor  80 , the front compression chamber A 4  is larger than the rear compression chamber A 5 . That is, the maximum volume of the front compression chamber A 4  is larger than the maximum volume of the rear compression chamber A 5 . 
     As shown in  FIGS. 2 and 3 , an introduction port  111  for introducing the suction fluid in the motor chamber A 1  into the front compression chamber A 4  is formed in the front rotor  60 . The introduction port  111  has an oval shape that is long in the radial direction R. The shape of the introduction port  111  is not limited to this, and is arbitrary. 
     The introduction port  111  extends through the front rotor  60  in the axial direction Z. The introduction port  111  is arranged near the radially outer end of the front rotor  60 . The introduction port  111  is arranged at a position where the introduction port  111  communicates with the front compression chamber A 4  at the phase at which the volume of the front compression chamber A 4  becomes large, and does not communicate with the front compression chamber A 4  at the phase at which the volume of the front compression chamber A 4  becomes small. 
     The introduction port  111  is provided near the boundary between the second front flat surface  72  and the front curving surface  73 , specifically, near the end in the circumferential direction of the front curving surface  73  close to the second front flat surface  72 . Further, the introduction port  111  is formed in the front curving surface  73  on the trailing side in the rotation direction with respect to the second front flat surface  72 . 
     As shown in  FIGS. 2 and 3 , communication holes  112  communicating with the introduction port  111  are formed in the front cylinder  40 . The communication holes  112  are provided at the positions corresponding to the introduction port  111 . When seen from the axial direction Z, the communication holes  112  are formed at the positions that overlap with the trajectory of the introduction port  111  when the front rotor  60  is rotated. The communication holes  112  extend in the circumferential direction of the rotary shaft  12 , and four communication holes  112  are separated from each other in the circumferential direction. Accordingly, even if the position of the introduction port  111  changes with the rotation of the front rotor  60 , the communication between the introduction port  111  and the communication holes  112  is easily maintained. 
     A discharge port  113  that discharges the compression fluid compressed in the rear compression chamber A 5  is formed in the rear rotor  80 . The discharge port  113  extends through the rear rotor  80  in the axial direction Z. The discharge port  113  is formed to be smaller than the introduction port  111 . The discharge port  113  is circular. The shape of the discharge port  113  is not limited to this, and is arbitrary. 
     The discharge port  113  is arranged at a position where the discharge port  113  communicates with the rear compression chamber A 5  at the phase at which the volume of the rear compression chamber A 5  becomes small, and does not communicate with the rear compression chamber A 5  at the phase at which the volume of the rear compression chamber A 5  becomes large. The discharge port  113  is provided near the boundary between the second rear flat surface  92  and the rear curving surface  93 , specifically, at the end in the circumferential direction of the rear curving surface  93  close to the second rear flat surface  92 . Further, the discharge port  113  is formed in the rear curving surface  93  that is on the leading side in the rotation direction with respect to the second rear flat surface  92 . 
     When seen from the axial direction Z, the introduction port  111  is arranged on the same side as the discharge port  113 , instead of the opposite side from the discharge port  113 , on the basis of the center line passing through the centers of the rotors  60  and  80 , and extending in the direction along which the flat surfaces  71  and  72  are arranged. However, the positions of the introduction port  111  and the discharge port  113  are arbitrary. A discharge valve that closes the discharge port  113  and makes the discharge port  113  open based on application of a specified pressure may be provided. The discharge valve is not essential. 
     As shown in  FIG. 1 , the compressor  10  includes a discharge chamber A 6  into which the compression fluid discharged from the discharge port  113  flows, and a discharge passage  114  that connects the discharge chamber A 6  and the outlet  11   b.  The discharge chamber A 6  is formed by the rear cylinder  50  and the rear housing member  22 . The discharge chamber A 6  is arranged between the discharge port  113  and the rear housing member  22 . When seen from the axial direction Z, the discharge chamber A 6  is formed in a ring shape so as to overlap with the trajectory of the discharge port  113  accompanying the rotation of the rear rotor  80 . Accordingly, it is possible to limit the situation in which the discharge port  113  and the discharge chamber A 6  do not communicate with each other, depending on the angular position of the rear rotor  80 . According to this configuration, the fluid discharged from the discharge port  113  is discharged from the outlet  11   b  via the discharge chamber A 6  and the discharge passage  114 . 
     The compressor  10  includes a communication mechanism  120  that switches between a communicating state in which the compression chambers A 4  and A 5  communicate with each other, and a non-communicating state in which the compression chambers A 4  and A 5  are not communicating with each other. A detailed configuration of the communication mechanism  120  is described below. 
     As shown in  FIGS. 2 to 4 , the communication mechanism  120  includes a front boss portion  121  as a first boss portion provided in the front rotor  60 , a front rotary valve  122  as a first engagement portion, a rear boss portion  123  as a second boss portion provided in the rear rotor  80 , and a rear rotary valve  124  as a second engagement portion. 
     The front boss portion  121  protrudes toward the rear rotor  80  from the front rotor surface  70 . The front boss portion  121  protrudes further toward the rear rotor surface  90  than the second front flat surface  72 . The front boss portion  121  includes a cylinder provided in the radially inner end of the front rotor surface  70 . The rotary shaft  12  is inserted into the front boss portion  121 . The outer diameter of the front boss portion  121  is substantially the same as the diameter of the wall through-hole  54 . The front boss portion  121  is fitted to be slidable from the first wall surface  52  to the wall through-hole  54 . 
     As shown in  FIG. 3 , the front rotary valve  122  protrudes toward the rear rotor  80  from the tip surface of the front boss  121 . Two front rotary valves  122  are provided at the positions separated in the circumferential direction. 
     The front rotary valves  122  have sectoral shapes. The inner circumferential surfaces of the front rotary valves  122  are flush with the inner circumferential surface of the front boss portion  121 , and contact the outer circumferential surface of the rotary shaft  12 . The outer circumferential surfaces of the front rotary valves  122  are flush with the outer circumferential surface of the front boss portion  121 . 
     As shown in  FIGS. 2 and 4 , the rear boss portion  123  protrudes toward the front rotor  60  from the rear rotor surface  90 . The rear boss portion  123  protrudes further toward the front rotor surface  70  than the second rear flat surface  92 . The rear boss portion  123  includes a cylinder provided in the radially inner end of the rear rotor surface  90 . The rotary shaft  12  is inserted into the rear boss portion  123 . The outer diameter of the rear boss portion  123  is substantially the same as the diameter of the wall through-hole  54 . The rear boss portion  123  is fitted to be slidable from the second wall surface  53  to the wall through-hole  54 . 
     The rear rotary valve  124  protrudes toward the front rotor  60  from the tip surface of the rear boss  123 . The rear rotary valve  124  consists of a columnar body including a curved inner circumferential surface and an outer circumferential surface. The inner circumferential surface of the rear rotary valve  124  is flush with the inner circumferential surface of the rear boss portion  123 , and contacts the outer circumferential surface of the rotary shaft  12 . The outer circumferential surface of the rear rotary valve  124  is flush with the outer circumferential surface of the front rotary valves  122 . The length of the circumferential direction of rear rotary valve  124  is the same as the interval distance of the circumferential direction of the front rotary valves  122 . 
     As shown in  FIGS. 5 and 6 , the rear rotary valve  124  is engaged with the two front rotary valves  122  in the circumferential direction. The rear rotary valve  124  is fitted between the rotary valves  122  by being sandwiched by the two front rotary valves  122  from the circumferential direction. The relative positions in the circumferential direction of the rotors  60  and  80  are specified by fitting the rotary valves  122  and  124 . 
     One sectoral connecting valve  125  is formed by the front rotary valves  122  and the rear rotary valve  124 . The connecting valve  125  is arranged in the wall through-hole  54 . The rotary valves  122  and  124  are engaged with each other within the wall through-hole  54 . 
     The connecting valve  125  does not have a closed ring shape, and has a sectoral shape. Therefore, an open space  126  where fluid can move is formed in the wall through-hole  54 . The open space  126  is formed between the rotary shaft  12  and a wall inner circumferential surface  54   a,  which is the inner circumferential surfaces of the wall through-hole  54 . The open space  126  is formed by the end faces in the circumferential direction of the connecting valve  125 , the outer circumferential surface of the rotary shaft  12 , and the wall inner circumferential surface  54   a.    
     The connecting valve  125  includes a valve outer circumferential surface  125   a  having the same diameter as the diameter of the wall through-hole  54 . The valve outer circumferential surface  125   a  is configured by the outer circumferential surfaces of the rotary valves  122  and  124 . Since the outer circumferential surfaces of the rotary valves  122  and  124  are flush with each other, the valve outer circumferential surface  125   a  forms one continuous circumferential surface. The valve outer circumferential surface  125   a  contacts the wall inner circumferential surface  54   a  of the wall through-hole  54 . The wall inner circumferential surface  54   a  is also an inner circumferential surface of the intermediate wall portion  51  formed in ring shape. 
     The communication mechanism  120  includes a communication passage  130  that communicates between the compression chambers A 4  and A 5 . The communication passage  130  includes a front-side opening  131 , a rear side opening  132 , and a communication groove  133 . 
     As shown in  FIG. 5 , the front-side opening  131  and the rear side opening  132  are formed in the intermediate wall portion  51 . The openings  131  and  132  are separated in the circumferential directions of the rotors  60  and  80 . The front-side opening  131  and the rear side opening  132  are arranged at either side of the vane  100 . The front-side opening  131  is formed on one surface of the vane  100  located on the trailing side in the rotation direction of the rotors  60  and  80 , and the rear side opening  132  is formed on the other surface of the vane  100  located on the leading side in the rotation direction of the rotors  60  and  80 , respectively. The openings  131  and  132  communicate with the vane groove  110 . 
     As shown in  FIG. 3 , the front-side opening  131  is opened toward the front compression chamber A 4  and the wall through-hole  54 . The front-side opening  131  is formed in the both of the first wall surface  52  and the wall inner circumferential surface  54   a  in the intermediate wall portion  51 . The front-side opening  131  is configured so that the fluid in the front compression chamber A 4  can be made to flow into the wall through-hole  54 . 
     The front-side opening  131  is not formed in the second wall surface  53 . That is, the front-side opening  131  does not extend through the intermediate wall portion  51  in the axial direction Z, and does not directly communicate with the front compression chamber A 4  and the rear compression chamber A 5  to each other. 
     As shown in  FIG. 2 , the rear side opening  132  is opened toward the rear compression chamber A 5  and the wall through-hole  54 . The rear side opening  132  is formed in both of the second wall surface  53  and the wall inner circumferential surface  54   a  in the intermediate wall portion  51 . The rear side opening  132  is configured so that the fluid in the rear compression chamber A 5  can be made to flow into the wall through-hole  54 . In contrast, the rear side opening  132  is not formed in the first wall surface  52 . That is, the rear side opening  132  does not extend through the intermediate wall portion  51  in the axial direction Z, and does not directly communicate with the front compression chamber A 4  and the rear compression chamber A 5  to each other. 
     As shown in  FIG. 5 , the front-side opening  131  has a half-U shape, and extends in the radial direction R. The rear side opening  132  has a half-U shape that is symmetrical to the front-side opening  131 . The shapes of the openings  131  and  132  are not limited to these, and are arbitrary. The vane  100  divides the front-side opening  131  and the rear side opening  132 . The vane  100  restricts the fluid from directly flowing into the rear side opening  132  from the front-side opening  131 . 
     The communication groove  133  is a part that is recessed outward in the radial direction of the wall inner circumferential surface  54   a.  The communication groove  133  is arranged between the front-side opening  131  and the rear side opening  132  in the wall inner circumferential surface  54   a  so as to bypass the vane  100 . The communication groove  133  extends in the circumferential direction of the wall inner circumferential surface  54   a.  The communication groove  133  communicates with the rear side opening  132 , and communicates with the open space  126 . The circumferential direction of the wall inner circumferential surface  54   a  matches the circumferential directions of the rotors  60  and  80 . Therefore, the circumferential direction of the wall inner circumferential surface  54   a  can also be said to be the circumferential directions of the rotors  60  and  80 . 
     In contrast, the communication groove  133  does not directly communicate with the front-side opening  131 . The communication groove  133  and the front-side opening  131  are separated in the circumferential direction of the wall inner circumferential surface  54   a.  Therefore, the fluid does not directly flow into the communication groove  133  from the front-side opening  131 . The communication groove  133  is not formed, and a groove-less surface  54   aa  exists between the communication groove  133  and the front-side opening  131  in the wall inner circumferential surface  54   a.    
       FIG. 5  shows a case where the connecting valve  125  is arranged radially inside of the front-side opening  131 . In this case, the connecting valve  125  closes the opening part that is radially inside of the front-side opening  131 . Accordingly, the inflow of the fluid that goes to the communication groove  133  from the front-side opening  131  is restricted. Accordingly, the compression chambers A 4  and A 5  are in the non-communicating state in which they are not communicating with each other. Especially, when the connecting valve  125  is arranged radially inside with respect to the groove-less surface  54   aa,  the valve outer circumferential surface  125   a  of the connecting valve  125  contacts the groove-less surface  54   aa.  Accordingly, the leakage of the fluid that goes to the communication groove  133  from the front-side opening  131  is regulated. 
       FIG. 6  shows a case where the connecting valve  125  is moved in the circumferential direction of the rotors  60  and  80  with respect to the front-side opening  131 . In this case, the connecting valve  125  does not close the opening part that is radially inside of the front-side opening  131 . Accordingly, the inflow of the fluid that goes to the communication groove  133  from the front-side opening  131  via the open space  126  is permitted. Accordingly, the fluid in the front compression chamber A 4  passes through the front-side opening  131 →the open space  126 →the communication groove  133 →the rear side opening  132 , and moves to the rear compression chamber A 5 . Accordingly, the compression chambers A 4  and A 5  are in the communicating state, in which they are communicating with each other. 
     The connecting valve  125  moves between the closed position for closing the front-side opening  131 , and the open position for opening the front-side opening  131  in accordance with the angular positions of the rotors  60  and  80 . When the connecting valve  125  is moved to the open position, the front-side opening  131  and the communication groove  133  communicate with each other via the open space  126 . 
     In this configuration, the communication period of the front compression chamber A 4  and the rear compression chamber A 5  in one cycle of rotation of the rotors  60  and  80  is defined by the length in the circumferential direction of the valve outer circumferential surface  125   a  (the angle range occupied by the connecting valve  125 ). Additionally, the timing at which the compression chambers A 4  and A 5  communicate with each other in one cycle of rotation of the rotors  60  and  80  is defined by the angular position of the connecting valve  125 . Accordingly, when the angular position of the connecting valve  125 , or the length in the circumferential direction of the valve outer circumferential surface  125   a  is adjusted, the timing at which the compression chambers A 4  and A 5  communicate with each other and the communication period are adjusted. 
     As shown in  FIGS. 4 and 5 , the inner end face  103 , which is a radially inside end face of the vane  100 , contacts the outer circumferential surfaces of the boss portions  121  and  123 , and the valve outer circumferential surface  125   a.  The outer circumferential surfaces of the boss portions  121  and  123  are flush with each other, the outer circumferential surfaces of the boss portions  121  and  123  are flush with the valve outer circumferential surface  125   a,  and the outer circumferential surfaces of the rotary valves  122  and  124  are flush with each other. The inner end face  103  of the vane  100  is a concave surface that is curved with the same curvature as the outer circumferential surfaces of the boss portions  121  and  123 , and the valve outer circumferential surface  125   a.  Therefore, the inner end face  103  of the vane  100  comes into surface contact with the outer circumferential surfaces of the boss portions  121  and  123 , and the valve outer circumferential surface  125   a.    
     An outer end face  104 , which is a radially outside end face of the vane  100 , is flush with the first part surface  57   a  of the rear cylinder  50 . The outer end face  104  of the vane  100  contacts the front cylinder inner circumferential surface  43  of the front cylinder  40 . The vane  100  is sandwiched by the outer circumferential surfaces of the boss portions  121  and  123  and the valve outer circumferential surface  125   a,  and the front cylinder inner circumferential surface  43  from the radial direction R. Accordingly, it is possible to limit the position shift in the radial direction R of the vane  100 . Additionally, it is possible to limit the fluid from leaking from the boundary part between the vane  100  (the inner end face  103 ) and the outer circumferential surfaces of the boss portions  121  and  123  and the valve outer circumferential surface  125   a,  or from the boundary part between the vane  100  (the outer end face  104 ) and the front cylinder inner circumferential surface  43 . 
     Using  FIGS. 7 to 13  in addition to  FIGS. 2 to 4 , a detailed description is given of the vane ends  101  and  102  and the curving surfaces  73  and  93 .  FIGS. 8, 12, and 13  schematically show the curvature change and the degree of curvature of a contact line. 
       FIG. 8  is a graph showing the displacement in the axial direction Z in accordance with the angular position on the rotor surface  70 . The continuous line in  FIG. 8  shows the displacement in the axial direction Z of the radially inner end of the front rotor surface  70 . The long dashed short dashed line in  FIG. 8  shows the displacement in the axial direction Z of the radially outer end of the front rotor surface  70 . The vertical axis of the graph in  FIG. 8  shows the displacement amount in the axial direction Z on the basis of the first front flat surface  71 . In  FIG. 8 , it is shown that the more distant from 0 the displacement in the axial direction Z becomes, the closer to the first wall surface  52  the front rotor surface  70  becomes. 
       FIG. 8  can also be said to be the graph showing the displacement in the axial direction Z of the rear rotor surface  90 . In this case, the continuous line in  FIG. 8  shows the displacement in the axial direction Z of the radially inner end of the rear rotor surface  90 . The long dashed short dashed line in  FIG. 8  shows the displacement in the axial direction Z of the radially outer end of the rear rotor surface  90 . The vertical axis of the graph in  FIG. 8  shows the displacement amount in the axial direction Z on the basis of the first rear flat surface  91 . In  FIG. 8 , it is shown that the more distant from 0 the displacement in the axial direction Z becomes, the closer to the second wall surface  53  the rear rotor surface  90  becomes. 
     As shown in  FIG. 7 , the vane ends  101  and  102  have curved shapes that are convex in the direction in which the vane ends  101  and  102  are separated from each other. The first vane end  101  is curved so as to be convex toward the front rotor surface  70 , and the second vane end  102  is curved so as to be convex toward the rear rotor surface  90 . The vane ends  101  and  102  extend in the vertical direction perpendicular to the axial direction Z, and are not inclined in the axial direction Z. 
     The vane ends  101  and  102  contact the curving surfaces  73  and  93 , which are curved in the axial direction Z, in a linear manner. The contacting part between the vane ends  101  and  102  and the curving surfaces  73  and  93  are shifted in accordance with the degrees of curvature in the axial direction Z of the curving surfaces  73  and  93 , more particularly, in accordance with the curvatures of the curving surfaces  73  and  93 . 
     Next, the curving surfaces  73  and  93  are described. Hereinafter, though a description is given of the front rotor surface  70 , the same applies to the rear rotor surface  90 . 
     The front flat surfaces  71  and  72  are flat surfaces that are perpendicular to the axial direction Z. Therefore, the radially inner ends and the radially outer ends of the front flat surfaces  71  and  72  are not displaced irrespective of the angular positions. In  FIG. 8 , the vicinity of 0 degrees corresponds to the second front flat surface  72 , and the vicinity of 180 degrees corresponds to the first front flat surface  71 . 
     As shown in  FIGS. 4 and 8 , the front curving surface  73  includes a front concave surface  74  that is curved in the axial direction Z so as to be concave toward the first wall surface  52 , and a front convex surface  75  that is curved in the axial direction Z so as to be convex toward the first wall surface  52 . 
     The front concave surface  74  is arranged closer to the first front flat surface  71  than the second front flat surface  72 , and continues from the first front flat surface  71 . The front convex surface  75  is arranged closer to the second front flat surface  72  than the first front flat surface  71 , and continues from the second front flat surface  72 . The front concave surface  74  is connected to the front convex surface  75 . The front curving surface  73  has an inflection point (inflection angle position) θm. 
     The angular range occupied by the front concave surface  74  is the same as the angular range occupied by the front convex surface  75 , and the angular positions at 90 degrees and 270 degrees are equivalent to the inflection point θm, respectively. The angular ranges may be different from each other, and the inflection point θm is not limited to the above-described angular position, and is arbitrary. 
     As shown in  FIG. 9 , the front concave surface  74  includes a front concave surface radially inner end  74   a  and a front concave surface radially outer end  74   b  as the opposite ends in the radial direction R. Similarly, the front convex surface  75  includes a front convex surface radially inner end  75   a  and a front convex surface radially outer end  75   b  as the opposite ends in the radial direction R. The radially inner ends  74   a  and  75   a  and the radially outer ends  74   b  and  75   b  are both circular. 
     The radially inner ends  74   a  and  75   a  form the radially inner end of the front curving surface  73 . The diameters of the radially inner ends  74   a  and  75   a  are the same as the outer diameter of the front boss portion  121 . The radially inner ends  74   a  and  75   a  are connected to each other. The front concave surface radially inner end  74   a  is connected to the radially inner end of the first front flat surface  71 , and the front convex surface radially inner end  75   a  is connected to the radially inner end of the second front flat surface  72 . As indicated by the continuous line in  FIG. 8 , the displacement waveform in the axial direction Z of the radially inner end of the front rotor surface  70  becomes a smooth curved line. 
     The radially outer ends  74   b  and  75   b  form the radially outer end of the front curving surface  73 . The radially outer ends  74   b  and  75   b  are connected to each other. The front concave surface radially outer end  74   b  is connected to the radially outer end of the first front flat surface  71 , and the front convex surface radially outer end  75   b  is connected to the radially outer end of the second front flat surface  72 . As indicated by the long dashed short dashed line in  FIG. 8 , the displacement waveform in the axial direction Z of the radially outer end of the front rotor surface  70  becomes a smooth curved line. 
     The curvature indicating the displacement condition in the axial direction Z in accordance with the angular position is changed between the radially inner ends  74   a  and  75   a  and the radially outer end  74   b  and  75   b.  In the following description, the curvature means the curvature with respect to the axial direction Z, and the radius of curvature means the radius of curvature of the curvature with respect to the axial direction Z. That is, the curvature and the radius of curvature are parameters representing the displacement with respect to the axial direction Z, and do not represent the curvature and the radius of curvature of the arcs of the radially inner ends  74   a  and  75   a  and the radially outer ends  74   b  and  75   b  seen from the axial direction Z, for example. 
     Particularly, the radius of curvature of the front concave surface radially inner end  74   a  is smaller than the radius of curvature of the front concave surface radially outer end  74   b.  As shown in  FIG. 8 , the curvature of the displacement curve in the axial direction Z of the front concave surface radially inner end  74   a  with respect to the angular change (phase) is smaller than the curvature of the displacement curve in the axial direction Z of the front concave surface radially outer end  74   b  with respect to the angular change. Accordingly, in the front concave surface  74 , the difference in the axial direction Z between the front concave surface radially outer end  74   b  and the front concave surface radially inner end  74   a  becomes gradually larger from the first front flat surface  71  toward the inflection point θm. 
     Additionally, the radius of curvature of the front convex surface radially inner end  75   a  is smaller than the radius of curvature of the front convex surface radially outer end  75   b.  As shown in  FIG. 8 , the curvature of the displacement curve in the axial direction Z of the front convex surface radially inner end  75   a  with respect to the angular change (phase) is larger than the curvature of the displacement curve in the axial direction Z of the front convex surface radially outer end  75   b  with respect to the angular change. Accordingly, in the front convex surface  75 , the difference between the front convex surface radially outer end  75   b  and the front convex surface radially inner end  75   a  becomes gradually smaller from the inflection point θm toward the second front flat surface  72 . 
     That is, the front curving surface  73  is formed to be gradually inclined such that the radially inner end is more separated from the first wall surface  52  than the radially outer end from the first front flat surface  71  toward the inflection point θm, and such that the radially inner end and the radially outer end approach the same position in the axial direction Z from the inflection point θm toward the second front flat surface  72 . That is, at the inflection point θm, which is the boundary part between the front concave surface  74  and the front convex surface  75 , the difference in the axial direction Z between the radially outer end and the radially inner end in the front curving surface  73  is maximized. In contrast, in the opposite ends in the circumferential direction in the front curving surface  73 , there is no difference between the radially outer end and the radially inner end, and the both are arranged at the same position in the axial direction Z. 
     Similarly, as shown in  FIGS. 4 and 8 , the rear curving surface  93  includes a rear concave surface  94  that is curved in the axial direction Z so as to be concave toward the second wall surface  53 , and a rear convex surface  95  that is curved in the axial direction Z so as to be convex toward the second wall surface  53 . The rear curving surface  93  has the inflection point θm at the same angular position as the front curving surface  73 . The rear concave surface  94  is connected to the rear convex surface  95 . The front concave surface  74  and the rear convex surface  95  are opposed to each other in the axial direction Z, and the front convex surface  75  and the rear concave surface  94  are opposed to each other in the axial direction Z. 
     As shown in  FIG. 10 , the rear concave surface  94  includes a rear concave surface radially inner end  94   a  and a rear concave surface radially outer end  94   b.  The rear convex surface  95  includes a rear convex surface radially inner end  95   a  connected to the rear concave surface radially inner end  94   a,  and a rear convex surface radially outer end  95   b  connected to the rear concave surface radially outer end  94   b.    
     The degrees of curvature of the rear concave surface  94  and the rear convex surface  95  are the same as the degrees of curvature of the front concave surface  74  and the front convex surface  75 . The radius of curvature of the rear concave surface radially inner end  94   a  is smaller than the radius of curvature of the rear concave surface radially outer end  94   b,  and the radius of curvature of the rear convex surface radially inner end  95   a  is smaller than the radius of curvature of the rear convex surface radially outer end  95   b.    
     The front concave surface  74  is formed such that the radius of curvature becomes gradually smaller from the front concave surface radially outer end  74   b  toward the front concave surface radially inner end  74   a.  The front convex surface  75  is formed such that the radius of curvature becomes gradually smaller from the front convex surface radially outer end  75   b  toward the front convex surface radially inner end  75   a.  Accordingly, the curvature change in the radial direction R in the front concave surface  74  and the front convex surface  75  is continuous. 
     As shown in  FIG. 11 , the front curving surface  73  and the rear curving surface  93  are mutually inclined in the axial direction Z such that the radially inner ends are more separated from the second wall surface  53  than the radially outer ends at least at the inflection point θm (the boundary part between the concave surfaces  74  and  94  and the convex surfaces  75  and  95 ). Then, when the vane  100  is arranged at the angular position corresponding to the inflection point θm, the first vane end  101  contacts both of the radially inner end and radially outer end of the front curving surface  73 , and the second vane end  102  contacts both of the radially inner end and radially outer end of the rear curving surface  93 . 
     In other words, the front curving surface  73  and the rear curving surface  93  are gradually concaved from the radially outer end toward the radially inner end at least at the inflection point θm, and the concave from the radially outer end toward the radially inner end becomes gentle from the inflection point θm toward the angular positions θ 1  and θ 2 . 
     A detailed description is given of the contacting manner between the curving surfaces  73  and  93  configured as described above and the vane end  101  and  102 . 
     As shown in  FIG. 12 , the front curving surface  73  is in line contact with the first vane end  101 . The contact line (line of contact) between the front curving surface  73  and the first vane end  101  is called a front contact line (front line of contact) P 1 . 
     As described above, the first vane end  101  extends in the vertical direction perpendicular to the axial direction Z, and the position of the axial direction Z is not displaced. In contrast, in the front curving surface  73 , the radius of curvature is different between the radially inner end and the radially outer end, and the radially inner end and the radially outer end are displaced in the axial direction Z at least at the inflection point θm. Therefore, the angular position at which the front curving surface  73  contacts the first vane end  101  differs between the radially inner end and radially outer end of the front curving surface  73 . Accordingly, the front contact line P 1  becomes a curved line instead of a straight line extending in the radial direction R. 
     Similarly, as shown in  FIG. 13 , the rear curving surface  93  is in line contact with the second vane end  102 . The contact line (line of contact) between the rear curving surface  93  and the second vane end  102  is called a rear contact line (rear line of contact) P 2 . 
     As described above, the second vane end  102  extends in the vertical direction perpendicular to the axial direction Z, and the position of the axial direction Z is not displaced. In contrast, in the rear curving surface  93 , the radius of curvature is different between the radially inner end and the radially outer end, and the radially inner end and the radially outer end are displaced in the axial direction Z at least at the inflection point θm. Therefore, similar to the front contact line P 1 , the rear contact line P 2  becomes a curved line instead of a straight line extending in the radial direction R. 
     A vane thickness D, which is the thickness of the vane  100 , is set such that the vane ends  101  and  102  contact the curving surfaces  73  and  93  from the radially inner ends to the radially outer ends, irrespective of the angular positions of the curving surfaces  73  and  93 . Particularly, the vane thickness D is set such that the vane ends  101  and  102  contact the radially inner ends of the curving surfaces  73  and  93 , when the vane  100  is arranged at the angular position corresponding to the inflection point θm. It can be said that the vane thickness D is the length of the vane  100  in the direction perpendicular to both of the axial direction Z and the longitudinal direction of the vane ends  101  and  102 . Therefore, the thickness direction of the vane  100  is the direction that is perpendicular to both of the axial direction Z and the longitudinal direction of the vane ends  101  and  102 . 
     The radii of curvature of the vane ends  101  and  102 , which are curved so as to be convex toward the rotor surfaces  70  and  90 , is arbitrary, as long as the vane ends  101  and  102  can contact the curving surfaces  73  and  93  from the radially inner ends to the radially outer ends, irrespective of the angular positions of the rotors  60  and  80 . For example, the larger the radii of curvature of the vane ends  101  and  102  are, the larger the difference in the circumferential direction of the contact position between the radially inner end and the radially outer end of the curving surfaces  73  and  93  becomes. In consideration of this point, the radii of curvature of the vane ends  101  and  102  may be made larger than the radius of curvature in the case where the vane ends  101  and  102  have semicircle shapes. Accordingly, the contact lines P 1  and P 2  can be more curved. 
     When the front curving surface  73  is curved in the axial direction Z so as to be close to the first wall surface  52  from a first angular position θ 1  toward a second angular position θ 2 , the rear curving surface  93 , which is opposed to the front curving surface  73 , is curved in the axial direction Z so as to be distant from the second wall surface  53  such that the separation distance from the front curving surface  73  becomes constant. That is, when one of the curving surfaces  73  and  93  is upwardly inclined, the other is downwardly inclined. Accordingly, when seen in the axial direction Z, the front contact line P 1  is curved in the direction opposite to the rear contact line P 2 . 
     The separation distance between the curving surfaces  73  and  93  being constant may mean that the separation distance is constant at angular positions of the same radius. When the curving surfaces  73  and  93  have an identical shape except for different diameters, the separation distance at arbitrary radius positions of the curving surfaces  73  and  93  becomes constant, without being changed in accordance with the angular positions. Additionally, the separation distance being constant means that some errors are included if the rotors  60  and  80  can be rotated within a range in which the vane ends  101  and  102  are contacting the curving surfaces  73  and  93 . 
     Next, using  FIGS. 14 and 15 , a detailed description is given of the positional relationship among the introduction port  111 , the discharge port  113 , and the openings  131  and  132 , and the compression chambers A 4  and A 5 . 
       FIG. 14B  is a cross-sectional view showing the rotors  60  and  80  and the vane  100  in the state shown in  FIG. 14A , and  FIG. 15B  is a cross-sectional view showing the rotors  60  and  80  and the vane  100  in the state shown in  FIG. 15A .  FIGS. 14B and 15B  schematically show the openings  131  and  132  and the open space  126  provided in the intermediate wall portion  51 . The state in which the openings  131  and  132  are connected via the open space  126  corresponds to the state in which the compression chambers A 4  and A 5  are communicating with each other. 
     As shown in  FIGS. 14A and 14B , the vane  100  does not enter into the front housing chamber A 2  in the circumstance in which the vane  100  contacts the second front flat surface  72  and the first rear flat surface  91 . In this case, the number of the front compression chamber A 4  is one, the front compression chamber A 4  is filled with the suction fluid, and the front compression chamber A 4  reaches the maximum volume. 
     In contrast, since a part of the vane  100  enters into the rear housing chamber A 3 , in the rear housing chamber A 3 , two rear compression chambers A 5  (a first rear compression chamber A 5   a  and a second rear compression chamber A 5   b ) are formed at either side of the vane  100 . The first rear compression chamber A 5   a  and the second rear compression chamber A 5   b  are divided by the contacting part between the second rear flat surface  92  and the second wall surface  53  and the vane  100 , and adjacent to each other in the circumferential direction. 
     The first rear compression chamber A 5   a  communicates with the rear side opening  132 , and does not communicate with the discharge port  113 . The second rear compression chamber A 5   b  communicates with the discharge port  113 , and does not communicate with the rear side opening  132 . The vane  100  divides the first rear compression chamber A 5   a  communicating with the rear side opening  132  and the second rear compression chamber A 5   b  communicating with the discharge port  113 , so that the rear side opening  132  does not directly communicate with the discharge port  113 . 
     Thereafter, when the rotary shaft  12  is rotated by the electric motor  13 , the rotors  60  and  80  are rotated. Then, the vane  100  is moved in the axial direction Z (the left and right directions in  FIG. 14 ), and a part of the vane  100  enters into the front housing chamber A 2 . Accordingly, as shown in  FIG. 15B , two front compression chambers A 4  (a first front compression chamber A 4   a  and second front compression chamber A 4   b ) are formed in either side of the vane  100 . The first front compression chamber A 4   a  and the second front compression chamber A 4   b  are divided by the contacting part of the second front flat surface  72  and the first wall surface  52  and vane  100 , and adjacent to each other in the circumferential direction. 
     The first front compression chamber A 4   a  communicates with the introduction port  111 , and does not communicate with the front-side opening  131 . The second front compression chamber A 4   b  communicates with the front-side opening  131 , and does not communicates with the introduction port  111 . The vane  100  divides the first front compression chamber A 4   a  communicating with the introduction port  111 , and the second front compression chamber A 4   b  communicating with the front-side opening  131 , so that the introduction port  111  and the front-side opening  131  do not directly communicate with each other. 
     When the rotors  60  and  80  are rotated in this state, the volumes of the compression chambers A 4  and A 5  are changed. In the first front compression chamber A 4   a,  the volume is increased and the suction fluid is drawn in from the introduction port  111 , and, in the second front compression chamber A 4   b,  the volume is decreased and the suction fluid is compressed. Similarly, in the second rear compression chamber A 5   b,  the volume is decreased and the fluid is compressed. In contrast, in the first rear compression chamber A 5   a,  the space itself becomes large. However, since the communication mechanism  120  is in the non-communicating state, the fluid does not flow into the first rear compression chamber A 5   a.    
     Thereafter, as shown in  FIGS. 15A and 15B , after the vane  100  passes the first front flat surface  71  and the second rear flat surface  92 , the compression chambers A 4  and A 5  (the second front compression chamber A 4   b  and the first rear compression chamber A 5   a ) communicate with each other. Accordingly, an intermediate pressure fluid having a higher pressure than the suction fluid compressed in the second front compression chamber A 4   b  is introduced into the first rear compression chamber A 5   a.  That is, the communication passage  130  communicates between the second front compression chamber A 4   b  and the first rear compression chamber A 5   a.    
     Thereafter, when the rotors  60  and  80  are rotated to the position at which the vane  100  contacts the second front flat surface  72  and the first rear flat surface  91 , all the intermediate pressure fluid in the second front compression chamber A 4   b  is introduced into the first rear compression chamber A 5   a,  and the compression chambers A 4  and A 5  do not communicate with each other. In contrast, the introduced intermediate pressure fluid is compressed as the fluid of the second rear compression chamber A 5   b  at the time of next rotations of the rotors  60  and  80 , and is discharged from the discharge port  113 . In this case, since the intermediate pressure fluid is further compressed in the second rear compression chamber A 5   b,  the compressed fluid whose pressure is made higher than the intermediate pressure fluid is discharged from the discharge port  113 . 
     By rotating the rotors  60  and  80 , in the compression chambers A 4  and A 5 , the cycle movement of suction and compression having 720 degrees as one cycle (two rotations of the rotors  60  and  80 ) is repeated. A two stage compression is performed in which the intermediate pressure fluid compressed in the front compression chamber A 4  is compressed again in the rear compression chamber A 5 . 
     Although the description has been given by distinguishing between the front compression chambers A 4   a  and A 4   b,  when the fact that the cycle movement having 720 degrees as one cycle is performed in the front compression chamber A 4 , the first front compression chamber A 4   a  is the front compression chamber A 4  whose phase is 0 degrees to 360 degrees, the second front compression chamber A 4   b  is the front compression chamber A 4  whose phase is 360 degrees to 720 degrees. That is, the space formed by the front rotor surface  70 , the first wall surface  52 , and the front cylinder inner circumferential surface  43  is divided into the front compression chamber A 4  whose phase is 0 degrees to 360 degrees, and the front compression chamber A 4  whose phase is 360 degrees to 720 degrees by the vane  100 . In other words, the vane  100  generates volume changes of the first chamber and the second chamber (the volume of the first chamber is increased, and the volume of the second chamber is decreased) with the rotations of the rotors  60  and  80 , in the state where the above-described space is divided into the first chamber into which the fluid is drawn in, and the second chamber from which the fluid is discharged. The same also applies to the first rear compression chamber A 5   a  and the second rear compression chamber A 5   b.    
     The communication passage  130  is a passage that communicates between the front compression chamber A 4  having a phase of 360 degrees to 720 degrees (a compression stage) and the rear compression chamber A 5  having a phase of 0 degrees to 360 degrees (a suction stage). The communication mechanism  120  makes the front compression chamber A 4  having a phase of 360 degrees to 720 degrees, and the rear compression chamber A 5  having a phase of 0 degrees to 360 degrees communicate with each other and not to communicate with each other. 
     Next, the volume changes of the compression chambers A 4  and A 5  is described by using  FIG. 16 . In  FIG. 16 , the broken line indicates the volume change of the front compression chamber A 4 , the long dashed short dashed line indicates the volume change of the rear compression chamber A 5 , and the continuous line indicates the substantial volume change for the combination of the compression chambers A 4  and A 5 , that is., the volume change of the entire compressor  10 , respectively. The volume changes of the compression chambers A 4  and A 5  are accompanied by a phase difference. As for the phase difference, the rotor surfaces  70  and  90  are curved in the axial direction Z so as to make the separation distance between them constant, and the volume changes of the compression chambers A 4  and A 5  are realized by one vane  100 . Additionally, the phase difference is realized since the compression spaces A 4  and A 5  communicate with each other in the second half of the compression stage of the front compression spaces A 4 . 
     As shown in  FIG. 16 , the phase of the volume change of the rear compression chamber A 5  is advanced compared with the volume change of the front compression chamber A 4 . The compressor  10  is configured such that, in the second half stage of the compression operation of the suction fluid in the front compression chamber A 4 , the compression chambers A 4  and A 5  communicate with each other, the suction of the intermediate pressure fluid into the rear compression chamber A 5  is started, and the volume of the rear compression chamber A 5  is increased. Therefore, as indicated by the continuous line in  FIG. 16 , the volume change of the entire compressor  10  forms a graph connecting the volume change of the front compression chamber A 4  and the volume change of the rear compression chamber A 5  to each other. 
     The operation of the present embodiment will now be described. 
     As shown in  FIGS. 12 and 13 , the contact lines P 1  and P 2  are not straight lines extending in the radial direction R, but are curved lines that are slightly curved in the circumferential direction. Accordingly, it becomes difficult for the vane  100  to be oscillated in the circumferential direction about at least one of the contact lines P 1  and P 2 . 
     The above-described embodiment has the following advantages. 
     (1) The compressor  10  includes the rotary shaft  12 , the front rotor  60  that includes the front rotor surface  70  formed into a ring shape, and that is rotated with rotation of the rotary shaft  12 , and a front cylinder side wall portion  42  that includes the front cylinder inner circumferential surface  43  opposed to the front rotor outer circumferential surface  62  in the radial direction R, and that houses the front rotor  60 . The compressor  10  includes the intermediate wall portion  51  that includes the first wall surface  52  opposed to the front rotor surface  70  in the axial direction Z, and the vane  100  that is inserted into the vane groove  110  formed in the intermediate wall portion  51 , and that moves in the axial direction Z with rotation of the front rotor  60 . The compressor  10  includes the front compression chamber A 4  that is defined by the front rotor surface  70 , the first wall surface  52  and the front cylinder inner circumferential surface  43 , and in which the volume is changed by the vane  100  with rotation of the front rotor  60 , and the suction and compression of the fluid are performed. 
     The vane  100  includes the first vane end  101  that is an end in the axial direction Z and contacts the front rotor surface  70 . The first vane end  101  is curved so as to be convex toward the front rotor surface  70 , and extends in the direction perpendicular to the axial direction Z. The front rotor surface  70  includes the front curving surface  73  that is displaced and curved in the axial direction Z in accordance with its angular position. 
     The front curving surface  73  includes the front concave surface  74  that is curved in the axial direction Z so as to be concave toward the first wall surface  52 , and the front convex surface  75  that is curved in the axial direction Z so as to be convex toward the first wall surface  52 . The front concave surface  74  is formed such that the radius of curvature of the front concave surface radially inner ends  74   a,  which are the opposite ends in the radial direction R of the front concave surface  74 , becomes smaller than the radius of curvature of the front concave surface radially outer end  74   b.  The front convex surface  75  is formed such that the radius of curvature of the front convex surface radially inner ends  75   a,  which are the opposite ends in the radial direction R of the front convex surface  75 , becomes smaller than the radius of curvature of the front convex surface radially outer end  75   b.    
     With this configuration, the front contact line P 1 , which is the contact part between the first vane end  101  and the front rotor surface  70 , is easily made into a curved shape. Accordingly, compared with the configuration in which the front contact line P 1  has a linear shape, it becomes more difficult for the vane  100  to be oscillated about the front contact line P 1 . 
     More particularly, when the first vane end  101  of the vane  100  that is not rotated with rotation of the front rotor  60  is contacting the front rotor surface  70 , the vane  100  is likely to be oscillated about the front contact line P 1 . 
     In contrast, the radii of curvature of the front concave surface radially inner end  74   a  and the front concave surface radially outer end  74   b  are changed, and the radii of curvature of the front convex surface radially inner end  75   a  and the front convex surface radially outer end  75   b  are changed, so that the front contact line P 1  becomes a curved line. Accordingly, the posture of the vane  100  is more stabilized, and it becomes more difficult for the vane  100  to be oscillated than in the case where the front contact line P 1  is a straight line. Accordingly, it is possible to suppress the noise, the vibration, and the leakage of the fluid due to the oscillation of the vane  100 . 
     The leakage of the fluid due to the oscillation of the vane  100  is, for example, the leakage of the fluid from the boundary part between the first vane end  101  and the front rotor surface  70 . Particularly, via the above-described boundary part, the leakage of the fluid from the second chamber (the second front compression chamber A 4   b  or the second rear compression chamber A 5   b ) in which compression is performed to the first chamber (the first front compression chamber A 4   a  or the first rear compression chamber A 5   a ) in which suction is performed can be considered. 
     (2) The vane  100  is inserted into the vane groove  110 . Accordingly, it is possible to regulate the rotation in the circumferential direction of the vane  100  by the contact between the vane  100  and the vane groove  110 . The vane  100  is inserted into the vane groove  110  so as to be movable in the axial direction Z. In order to smoothly perform the movement of the vane  100  in the axial direction Z, a slight gap (clearance) is provided between the vane  100  and the vane groove  110 . Therefore, the vane  100  may be oscillated in the vane groove  110 . In this regard, according to the present embodiment, it is possible to suppress the oscillation of the vane  100  in the vane groove  110  by making the front contact line P 1  into a curved shape. Accordingly, it is possible to suppress the oscillation of the vane  100  in the vane groove  110 , while smoothly performing the movement of the vane  100  in the axial direction Z. 
     (3) The vane  100  has a plate-like shape having a thickness in the direction perpendicular to both of the axial direction Z and the longitudinal direction of the first vane end  101 . The vane thickness D is set such that the vane end  101  contacts the curving surface  73  from the radially inner end to the radially outer end irrespective of the angular position of the front rotor  60 . With this configuration, irrespective of the angular position of the front curving surface  73 , the state is maintained where the first vane end  101  is contacting from the radially inner end to the radially outer end of the front curving surface  73 . Accordingly, it becomes difficult for a part to be generated at which the first vane end  101  does not contact the front curving surface  73 , while making the front contact line P 1  into a curved shape. Therefore, it is possible to suppress the leakage of the fluid from the boundary part between the first vane end  101  and the front curving surface  73 . 
     As already described, the radially inner end of the front curving surface  73  is most concaved with respect to the radially outer end at the inflection point θm. In view of this point, the vane thickness D may be set such that the first vane end  101  contacts the radially inner end of the front curving surface  73 , when the vane  100  is arranged at the angular position corresponding to the inflection point θm. Accordingly, irrespective of the angular position of the front rotor  60 , it is expected that the first vane end  101  contacts the front curving surface  73  from the radially inner end to the radially outer end. 
     (4) The front rotor surface  70  includes the first front flat surface  71  that is separated from the first wall surface  52 , and the second front flat surface  72  that is separated in the circumferential direction from the first front flat surface  71 , and that contacts the first wall surface  52 . The front curving surface  73  connects the front flat surfaces  71  and  72  to each other, and is curved in the axial direction Z so as to be gradually closer to the first wall surface  52  from the first front flat surface  71  toward the second front flat surface  72 . The front concave surface  74  is arranged closer to the first front flat surface  71  than the second front flat surface  72 , and the front convex surface  75  is arranged closer to the second front flat surface  72  than the first front flat surface  71 . The front concave surface  74  is connected to the front convex surface  75 . 
     In accordance with this configuration, the difference between the radially inner end and radially outer end of the front curving surface  73  is maximized in the boundary part between the front concave surface  74  and the front convex surface  75 , and the difference gradually becomes smaller toward the front flat surfaces  71  and  72 . Accordingly, it is possible to make the connection position (near the angular positions θ 1 , θ 2 ) between the front curving surface  73  and the front flat surfaces  71  and  72  into a smooth curved surface. Accordingly, it is possible to smoothly slide the front rotor surface  70  and the first vane end  101  with rotation of the front rotor  60 . 
     (5) Especially, it is possible to divide, by the contact position between the second front flat surface  72  and the first wall surface  52 , and the vane  100 , the front compression chamber A 4  (the first front compression chamber A 4   a ) in which the suction is performed, from the front compression chamber A 4  (the second front compression chamber A 4   b ) in which the compression is performed. Accordingly, it is possible to suppress the leakage of the fluid between the first and second front compression chambers A 4   a  and A 4   b,  and the efficiency is improved. 
     (6) The compressor  10  includes the rear rotor  80  that is rotated with the rotation of rotary shaft  12 , and the rear cylinder side wall portion  55  that includes the rear cylinder inner circumferential surface  56  opposed to the rear rotor outer circumferential surface  82  in the radial direction R, and that houses the rear rotor  80 . The rear rotor  80  includes the rear rotor surface  90  that are opposed to the front rotor surface  70  in the axial direction Z, and that is formed into a ring shape. The intermediate wall portion  51  is arranged between the rotors  60  and  80 , and includes the second wall surface  53  opposed to the rear rotor surface  90  in the axial direction Z. The vane  100  includes the second vane end  102  contacting the rear rotor surface  90 . The compressor  10  includes the rear compression chamber A 5  that is defined by the rear rotor surface  90 , the second wall surface  53  and the rear cylinder inner circumferential surface  56 , and in which the volume is changed by the vane  100  with rotation of the rear rotor  80 , and the suction and compression of the fluid are performed. 
     The rear rotor surface  90  includes the rear curving surface  93  including the rear concave surface  94  and the rear convex surface  95  as the second concave surface and the second convex surface. The front concave surface  74  and the rear convex surface  95  are opposed to each other in the axial direction Z, and the front convex surface  75  and the rear concave surface  94  are opposed to each other in the axial direction Z. Additionally, the curving surfaces  73  and  93  have the inflection points θm at an identical angle position, and are inclined such that the radially inner ends of the curving surfaces  73  and  93  are more separated from each other than the radially outer ends at least at the inflection points θm. That is, at least at the inflection points θm, the distance between the radially inner ends of the curving surfaces  73  and  93  is larger than the distance between the radially outer ends. Then, when the vane  100  is arranged at the angular position corresponding to the inflection point θm, the vane ends  101  and  102  contact the radially inner ends of the curving surfaces  73  and  93 . 
     With this configuration, when the rotors  60  and  80  are rotated, the vane  100  is moved in the axial direction Z in the state where the vane ends  101  and  102  are contacting the rotor surfaces  70  and  90 , and the suction and compression of the fluid are performed in the compression chambers A 4  and A 5 . Accordingly, it is possible to perform the suction and compression of the fluid in the compression chambers A 4  and A 5 , without providing the vane  100  corresponding to each of the compression chambers A 4  and A 5 . 
     Additionally, with the present embodiment, in the concave surfaces  74  and  94 , the radius of curvature of the radially inner end is smaller than the radius of curvature of the radially outer end, and in the convex surfaces  75  and  95 , the radius of curvature of the radially inner end is smaller than the radius of curvature of the radially outer end. Accordingly, since both contact lines P 1  and P 2 , which are the contact lines between the curving surfaces  73  and  93  and the vane ends  101  and  102 , can be made into curved shapes, it is possible to more preferably suppress the oscillation of the vane  100 . 
     By configuring the curving surfaces  73  and  93  as described above, the radially inner ends of the curving surfaces  73  and  93  are more separated from each other than the radially outer ends at least at the inflection points θm. In this regard, with the present embodiment, when the vane  100  is arranged at the angular position corresponding to the inflection point θm, the vane ends  101  and  102  contact the radially inner ends of the curving surfaces  73  and  93 . Accordingly, it becomes difficult for a gap to be produced between the vane ends  101  and  102  and the curving surfaces  73  and  93 , while making both contact lines P 1  and P 2  into curved shapes. 
     (7) The rear rotor surface  90  includes the rear flat surfaces  91  and  92  arranged at positions mutually shifted in the axial direction Z. The second rear flat surface  92  contacts the second wall surface  53 . The rear curving surface  93  connects the rear flat surfaces  91  and  92 . The first front flat surface  71  and the second rear flat surface  92  are opposed to each other, and the second front flat surface  72  and the first rear flat surface  91  are opposed to each other. With this configuration, since the first rear flat surface  91  is arranged at the position opposed to the second front flat surface  72 , the separation distance between them becomes constant, and a trouble hardly occurs in the movement of the vane  100 , and a gap between the vane  100  and the rotor surfaces  70  and  90  is hardly generated. The same also applies to the rear compression chamber A 5 . 
     (8) The front rotor surface  70  includes the second front flat surface  72  as a contact surface that is contacting the first wall surface  52 . The pair of front curving surfaces  73  are provided on the opposite sides in the circumferential direction of the rotary shaft  12  with respect to the second front flat surface  72 . The pair of front curving surfaces  73  are each curved to the axial direction Z so as to be gradually separated from the second front flat surface  72 , as the front curving surfaces  73  are separated from the second front flat surface  72  in the circumferential direction. Also, the pair of front curving surfaces  73  are formed such that the front contact line P 1 , which is the contact line with the first vane end  101 , is bent in the circumferential direction. That is, the pair of front curving surfaces  73  are formed such that the curvature of the displacement curve in the axial direction Z with respect to the angular change differs in accordance with the position in the radial direction R. With this configuration, the advantage of (1) is produced. 
     The above-described embodiment may be modified as follows. The above-described embodiment and the following modifications can be combined as long as the combined modifications remain technically consistent with each other. 
     The rear rotor  80  may have a larger diameter than the front rotor  60 . 
     Although the rotors  60  and  80  have different diameters, this is not a limitation, and may have the same diameter. That is, the volumes of the compression chambers A 4  and A 5  may be the same. 
     The front flat surfaces  71  and  72  and the rear flat surfaces  91  and  92  may be omitted. That is, the entire rotor surfaces  70  and  90  may be curving surfaces. 
     The first vane end  101  and the front rotor surface  70  are not limited to the configuration in which they contact each other over the entire part from the radially inner end to the radially outer end, and may be configured to contact each other over a partial range in the radial direction. Additionally, the first vane end  101  and the front rotor surface  70  are not limited to the configuration in which they contact each other over the entire circumference, and may be configured to contact each other over a partial angular range. The same applies to the second vane end  102  and the rear rotor surface  90 . 
     The number of the vane  100  is arbitrary, and may be plural, for example. Additionally, the circumferential direction position of the vane  100  is arbitrary. 
     The shapes of the vane  100  and the vane groove  110  are not limited to those in each of the embodiments, as long as the shapes allow the movement of the vane  100  in the axial direction Z, while the movement in the circumferential direction is restricted. For example, the vane may have a sectoral shape. 
     Additionally, the vane may be configured to move in the axial direction Z like a pendulum that moves about a predetermined place. That is, the vane may be configured to move in the axial direction Z in accordance with rotational movement, and not limited to linear movement. 
     The specific shapes of the cylinders  40  and  50  are arbitrary. For example, the bulged part  46  may be omitted. Additionally, though the cylinders  40  and  50  are different bodies, they may be integrally formed. 
     Similarly, the specific shapes of the housings  21  and  22  are also arbitrary. 
     The cylinders  40  and  50  may be omitted. In this case, the inner circumferential surface of the housing  11  may form the compression chambers A 4  and A 5 . In this configuration, the housing  11  corresponds to the first cylindrical portion and the second cylindrical portion. 
     The electric motor  13  and the inverter  14  may be omitted. That is, the electric motor  13  and the inverter  14  are not essential in the compressor  10   
     The rotors  60  and  80  may be each fixed to the rotary shaft  12  so as to be integrally rotated with the rotary shaft  12 , or only one of the rotors  60  and  80  may be attached to the rotary shaft  12  to be integrally rotated with the rotary shaft  12 , and the other may be attached to the rotary shaft  12  to be rotatable with respect to the rotary shaft  12 . Even in this case, since the rotary valves  122  and  124  are engaged with each other in the circumferential direction, with the rotation of one of the rotors  60  and  80 , the other is also rotated. 
     The outer circumferential surfaces of the boss portions  121  and  123  are not flush, and may have stepped shapes. In this case, the inner end face  103  of the vane  100  may similarly have a stepped shape, so that a gap is not formed. 
     As shown in  FIGS. 17 and 18 , the communication mechanism  200  may be formed so as to bypass the intermediate wall portion  51 . For example, the communication mechanism  200  may communicate the front compression chamber A 4  with the rear compression chamber A 5  via the communication passage  201  formed in the cylinder side wall portions  42  and  55 . The communication passage  201  includes a front-side opening formed in the part that forms the second front compression chamber A 4   b  of the front cylinder inner circumferential surfaces  43 , and a rear side opening in the part that forms the first rear compression chamber A 5   a  of the rear cylinder inner circumferential surfaces  56 , and connects these openings to each other. In this case, the communication mechanism  200  is switched to the non-communicating state when the phase of the front compression chamber A 4  is 0 degrees to 360 degrees, and to the communicating state when the phase of the front compression chamber A 4  is 360 degrees to 720 degrees. 
     In this case, the boss portions  121  and  123  and the rotary valves  122  and  124  may be omitted. That is, it is not essential that the rotors  60  and  80  contact or engage with each other. 
     In this configuration, the diameter of the wall through-hole  54  may be reduced, so that the wall inner circumferential surface  54   a  and the rotary shaft  12  contact or are close to each other. Additionally, the inner end face  103  of the vane  100  may directly contact the rotary shaft  12 . 
     The communication groove  133  may communicate with both openings  131  and  132 . In this case, the connecting valve  125  may have a fully closed ring shape in which the open space  126  is not formed. That is, the configuration may be adopted in which the rotary valves  122  and  124  are formed in the entire circumference in the engaged state. Additionally, when the communication groove  133  communicates with both openings  131  and  132 , the configuration may be adopted in which the rotary valves  122  and  124  are omitted, and the boss tip surfaces  121   a  and  123   a  directly contact each other. That is, the rotary valves  122  and  124  are not essential. Even in this case, the communication mechanism  120  can be said to be in the non-communicating state when the phase of the front compression chamber A 4  is 0 to 360 degrees, and is switched to the communicating state when the phase is 360 to 720 degrees. 
     As long as the rotary valves  122  and  124  are engaged with each other in the circumferential direction, the specific engagement manner is arbitrary. For example, two rear rotary valves  124  may be provided, and the front rotary valve  122  may be arranged between the rear rotary valves  124 . 
     As long as the openings  131  and  132  are mutually separated in the circumferential direction, their specific positions are arbitrary. 
     Only one of the front concave surface  74  and the front convex surface  75 , and the rear concave surface  94  and the rear convex surface  95  may be configured to produce a curvature change. That is, at least one of the contact lines P 1  and P 2  may have a curved shape. 
     The compression chambers A 4  and A 5  do not necessarily need to communicate with each other. That is, the communication mechanism  120  may be omitted. In this case, the compressor  10  may be configured such that, in each of the compression chambers A 4  and A 5 , the suction fluid is drawn in, and the compressed fluid is discharged. For example, a discharge port may be provided in the front rotor  60 , and the compressed fluid may be discharged from the discharge port, or a suction port may be provided in the rear rotor  80 , and the suction fluid may be introduced from the suction port. 
     One of the rotors  60  and  80  may be omitted. For example, as shown in  FIG. 19 , the front rotor  60  may be omitted. In this case, the front compression chamber A 4  is also omitted. That is, the two rotors and the two compression chambers are not essential. 
     In this configuration, the suction port  211  may be formed in the intermediate wall portion  51  so that the suction fluid is introduced into the rear compression chamber A 5 . Additionally, an energizing part  212  for urging the vane  100  to the rear rotor surface  90  may be provided. With this configuration, the vane  100  is moved in the axial direction Z while sliding on the rear rotor surface  90  with rotation of the rear rotor  80 . Accordingly, the volume change is caused in the rear compression chamber A 5 , and the suction and compression of the suction fluid are performed in the rear compression chamber A 5 . 
     Further, when the front rotor  60  is omitted, the length in the radial direction R of the vane  100  may be the same as the length in the radial direction R of the rear rotor surface  90 . In this case, the vane groove  110  may be formed only in the intermediate wall portion  51 , and does not necessarily need to be formed in the rear cylinder side wall portion  55 . 
     Additionally, in this modification, the inner end face  103  of the vane  100  may contact the rotary shaft  12  (particularly, the outer circumferential surface of the rotary shaft  12 ). Additionally, when the front rotor  60  is omitted, the first rear flat surface  91  may be omitted. 
       FIGS. 20 and 21  shows the inner end face  103  of the vane  100  curved so as to be concave toward the outside in the radial direction R and the outer circumferential surface of the front boss portion  121  curved so as to be convex toward the outside in the radial direction R. As shown in  FIGS. 20 and 21 , the curvature of the inner end face  103  of the vane  100  may be smaller than the curvature of the outer circumferential surface of the front boss portion  121 . That is, the inner end face  103  of the vane  100  may be concave to the outside in the radial direction R, and may be more gently curved than the outer circumferential surface of the front boss portion  121 . 
     With this configuration, it is possible to prevent the curvature of the inner end face  103  of the vane  100  from becoming larger than the curvature of the outer circumferential surface of the front boss portion  121  due to a manufacturing error, and the like. Accordingly, it is possible to suppress the inconvenience caused by the curvature of the inner end face  103  of the vane  100  becoming larger than the curvature of the outer circumferential surface of the front boss portion  121 . 
     More particularly, if the curvature of the inner end face  103  of the vane  100  is made the same as the curvature of the outer circumferential surface of the front boss portion  121 , the curvature of the inner end face  103  of the vane  100  may become larger than the curvature of the outer circumferential surface of the front boss portion  121  because of a manufacturing error, and the like. In this case, when both ends of the inner end face  103  of the vane  100  are caught in the outer circumferential surface of the front boss portion  121 , hindering the movement in the axial direction Z of the vane  100  or wearing the inner end face  103  of the vane  100  from both ends. 
     In this regard, with this modification, by positively curving the inner end face  103  of the vane  100  more gently than the outer circumferential surface of the front boss portion  121 , even when a manufacturing error and the like occurs, it is possible to prevent the curvature of the inner end face  103  of the vane  100  from becoming larger than the curvature of the outer circumferential surface of the front boss portion  121 . Accordingly, it is possible to suppress the inconvenience caused by the curvature of the inner end face  103  of the vane  100  becoming larger than the curvature of the outer circumferential surface of the front boss portion  121 . 
     Additionally, since the inner end face  103  of the vane  100  is more gently curved than the outer circumferential surface of the front boss portion  121 , a gap is generated in the second front compression chamber A 4   b  between the inner end face  103  of the vane  100  and the outer circumferential surface of the front boss portion  121 . In the second front compression chamber A 4   b,  the compressed fluid flows into the gap between the inner end face  103  of the vane  100  and the outer circumferential surface of the front boss portion  121 . The compressed fluid presses the vane  100  toward the outer side in the radial direction R, so that the gap between the outer end face  104  of the vane  100  and the front cylinder inner circumferential surface  43  is sealed. 
     Incidentally, the outer circumferential surface of the front boss portion  121  is flush with the outer circumferential surface of the rear boss portion  123 . It thus can also be said that the curvature of the inner end face  103  of the vane  100  is smaller than the curvature of the outer circumferential surface of the rear boss portion  123 . Similarly, the outer circumferential surfaces of the boss portions  121  and  123  are flush with the valve outer circumferential surface  125   a.  It thus can also be said that the curvature of the inner end face  103  of the vane  100  is smaller than the curvature of the valve outer circumferential surface  125   a.    
     Since the rotary shaft  12  is inserted through (in other words, inserted into) the boss portions  121  and  123 , it can be said that the boss portions  121  and  123  (and the connecting valve  125 ) is a rotor cylindrical portion that is rotated with rotation of the rotary shaft  12 . In this case, it can also be said that the curvature of the inner end face  103  of the vane  100  is smaller than the curvature of the outer circumferential surface of the rotor cylindrical portion. 
     Further, as in the modification shown in  FIG. 19 , when the inner end face  103  of the vane  100  is caused to contact the outer circumferential surface of the rotary shaft  12 , the curvature of the inner end face  103  of the vane  100  is preferably smaller than the curvature of the outer circumferential surface of the rotary shaft  12  curved so as to be convex toward the outside in the radial direction R. 
       FIG. 20  shows the outer end face  104  of the vane  100  curved so as to be convex toward the outside in the radial direction R and the front cylinder inner circumferential surface  43  of the front cylinder  40  curved so as to be convex toward the outside in the radial direction R. As shown in  FIG. 20 , the curvature of the outer end face  104  of the vane  100  may be greater than the curvature of the front cylinder inner circumferential surface  43  of the front cylinder  40 . That is, the outer end face  104  of the vane  100  may be convex toward the outside in the radial direction R, and may be more greatly curved than the front cylinder inner circumferential surface  43 . 
     With this configuration, it is possible to prevent the curvature of the outer end face  104  of the vane  100  from becoming smaller than the curvature of the front cylinder inner circumferential surface  43  due to a manufacturing error, and the like. 
     More particularly, if the curvature of the outer end face  104  of the vane  100  is made the same as the curvature of the front cylinder inner circumferential surface  43 , the curvature of the outer end face  104  of the vane  100  may become smaller than the curvature of the front cylinder inner circumferential surface  43  because of a manufacturing error, and the like. In this case, when both ends of the outer end face  104  of the vane  100  are caught in the front cylinder inner circumferential surface  43 , hindering the movement in the axial direction Z of the vane  100  or wearing the outer end face  104  of the vane  100  from both ends. 
     In this regard, with this modification, by positively curving the outer end face  104  of the vane  100  more greatly than the front cylinder inner circumferential surface  43 , even when a manufacturing error and the like occurs, it is possible to prevent the curvature of the outer end face  104  of the vane  100  from becoming smaller than the curvature of the front cylinder inner circumferential surface  43 . Accordingly, it is possible to suppress the inconvenience caused by the curvature of the outer end face  104  of the vane  100  becoming smaller than the curvature of the front cylinder inner circumferential surface  43 . 
     Additionally, since the outer end face  104  of the vane  100  is more greatly curved than the front cylinder inner circumferential surface  43 , a gap is generated in the second front compression chamber A 4   b  between the outer end face  104  of the vane  100  and the front cylinder inner circumferential surface  43 . In the second front compression chamber A 4   b,  the compressed fluid flows into the gap between the outer end face  104  of the vane  100  and the front cylinder inner circumferential surface  43 . The compressed fluid presses the vane  100  toward the inner side in the radial direction R, so that the gap between the inner end face  103  of the vane  100  and the outer circumferential surface of the front boss portion  121  is sealed. 
     The curvature of the inner end face  103  of the vane  100  may be same as the curvature of the outer circumferential surface of the front boss portion  121 , and the curvature of the outer end face  104  of the vane  100  may be greater than the curvature of the front cylinder inner circumferential surface  43 . Also, the curvature of the inner end face  103  of the vane  100  may be smaller than the curvature of the outer circumferential surface of the front boss portion  121 , and the curvature of the outer end face  104  of the vane  100  may be the same as the curvature of the front cylinder inner circumferential surface  43 . 
     As shown in  FIG. 22 , in the outer end face  104  of the vane  100 , the curvatures are different between the part where the first front compression chamber A 4   a  is disposed and the part where the second front compression chamber A 4   b  is disposed. Particularly, the outer end face  104  of the vane  100  may include a first outer end face  221  that is provided on the first front compression chamber A 4   a  (leading side in the rotation direction) and has a curvature larger than the curvature of the front cylinder inner circumferential surface  43 , and a second outer end face  222  that is provided on the second front compression chamber A 4   b  (on the trailing side in the rotation direction) and has a curvature larger than the curvature of the first outer end face  221 . The first outer end face  221  is on the leading side in the rotation direction of the second outer end face  222 . This configuration improves the sealing property in addition to the above-described advantages. 
     More particularly, with this modification, the curvature of the first outer end face  221  is closer to the curvature of the front cylinder inner circumferential surface  43  than the curvature of the second outer end face  222 . Thus, the contact part between the first outer end face  221  and the front cylinder inner circumferential surface  43  is easily extended in the circumferential direction, increasing the contact area between the first outer end face  221  and the front cylinder inner circumferential surface  43 . This improves the sealing property between the outer end face  104  of the vane  100  and the front cylinder inner circumferential surface  43 . 
     In contrast, the second outer end face  222  in the second front compression chamber A 4   b  is more greatly curved than the first outer end face  221 . Thus, a gap is easily formed in the second front compression chamber A 4   b  between the second outer end face  222  and the front cylinder inner circumferential surface  43 . Accordingly, the compressed fluid easily enters between the second outer end face  222  and the front cylinder inner circumferential surface  43 . Since the compressed fluid presses the vane  100  toward the inner side in the radial direction R, the sealing property between the inner end face  103  of the vane  100  and the outer circumferential surface of the front boss portion  121  is improved. 
     The vane  100  may be formed by multiple components. For example, the vane  100  may include a vane body that is inserted into the vane groove  110  and a front tip seal that is provided between the vane body and the front rotor surface  70  and contacts the front rotor surface  70 . In this case, the front tip seal or an end of the front tip seal forms an end in the axial direction Z of the vane  100  and corresponds to a vane end. 
     Likewise, the vane  100  may include a rear tip seal that is provided between the vane body and the rear rotor surface  90  and contacts the rear rotor surface  90 . In this case, the rear tip seal or an end of the rear tip seal corresponds to a vane end. 
     The compressor  10  may be used for devices other than an air-conditioner. For example, the compressor  10  may be used to supply compressed air to a fuel cell mounted in a fuel cell vehicle. 
     The compressor  10  may be mounted on any structure other than a vehicle. 
     The fluid to be compressed by the compressor  10  is not limited to refrigerant including oil, and is arbitrary.