Patent Publication Number: US-9429123-B2

Title: Vane pump

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2013-260876 filed on Dec. 18, 2013, the entire content of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to a vane pump. 
     2. Related Art 
     A vane pump includes a rotating rotor, a cam ring that is arranged to surround the rotor, a plurality of vanes (wings) that are slidably held by a plurality of vane grooves which are disposed in a radiation direction of the rotor, and a plurality of pump chambers that are partitioned by the two vanes which are adjacent in the vicinity of the rotor. The volume of the pump chamber is repeatedly increased and decreased by the rotation of the rotor. A plurality of suction ports are disposed in a side plate or the like at a position that corresponds to the expansion process of the pump chamber and a plurality of discharge ports are disposed in the side plate or the like at a position that corresponds to the contraction process. The vane pump supplies, for example, a working oil to a target device that is a supply target (refer to, for example, JP-A-2007-162554). 
     SUMMARY OF THE INVENTION 
     The suction area where the working oil is suctioned increases when a position of an end portion of the rotor on the rotation shaft side becomes closer to the rotation shaft and an opening of a supply unit of the side plate is widened. In this manner, the amount of suction of the working oil is increased and the suction efficiency is improved. However, the area where the vanes are supported by the side plate or the like is decreased as the supply unit becomes closer to the rotation shaft. As a result, the vanes become unstable in posture and, for example, the vanes are inclined such that corners of the vanes come into contact with the side plate or the like. This may result in burning of the vanes and the side plate or an abnormal noise. 
     An illustrative aspect of the invention is to suppress instability of a posture of a vane and improve suction efficiency of a supply unit of a side plate. 
     According to an aspect of the invention, there is provided a vane pump including a rotor that is coupled with a rotation shaft to rotate, a plurality of vanes that are slidably held by a plurality of vane grooves which are disposed in a radiation direction in an outer circumferential portion of the rotor, a cam ring that is arranged to surround the rotor and the plurality of vanes, and a side plate that covers the cam ring and has a supply unit which supplies a working fluid into the cam ring between the cam ring, an outer circumference of the side plate being recessed to a radially inner side of the rotation shaft to form the supply unit, in which an outer circumference of the supply unit and an inner circumference of the cam ring are shaped along each other. 
     In the aspect, the vane pump may further include another side plate that is arranged on a side opposite to the side plate across the cam ring to cover the cam ring and has another supply unit which supplies the working fluid into the cam ring between the cam ring, an outer circumference of said another side plate being recessed to the radially inner side of the rotation shaft to form said another supply unit, in which an outer circumference of said another supply unit and the inner circumference of the cam ring are shaped along each other. 
     In the aspect, the side plate may have a through-hole, on the radially inner side of the rotation shaft compared to the supply unit, which supplies the working fluid pressing the plurality of vanes to allow the plurality of vanes to protrude from the rotor into the cam ring, and a radially outer side of the rotation shaft in the through-hole may be shaped along the inner circumference of the cam ring. 
     According to any aspect of the invention, instability of the posture of the vanes can be suppressed, and the suction efficiency of the supply unit of the side plate can be improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an overall view of a vane pump to which this configuration example is applied. 
         FIG. 2  is a cross-sectional view taken along line II-II of  FIG. 1 . 
         FIG. 3  is a cross-sectional view taken along line III-III of  FIG. 1 . 
         FIG. 4  is a view illustrating an inner portion of a pump unit. 
         FIG. 5  is an overall view of an inner side plate of this configuration example. 
         FIG. 6  is an overall view of an outer side plate of this configuration example. 
         FIGS. 7A to 7C  are views illustrating a cam ring of this configuration example in detail. 
         FIG. 8  is a view illustrating an operation of a vane in the vicinity of a suction port of this configuration example. 
         FIG. 9  is a view illustrating the operation of the vane in the vicinity of the suction port of this configuration example. 
         FIG. 10  is a view illustrating an inclination of the vane of this configuration example. 
         FIG. 11  is an overall view of an inner side plate of another configuration example. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, configuration examples of the invention will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is an overall view of a vane pump  1  to which this configuration example is applied.  FIG. 2  is a cross-sectional view taken along line II-II of  FIG. 1 .  FIG. 3  is a cross-sectional view taken along line of  FIG. 1 .  FIG. 4  is a view illustrating an inner portion of a pump unit  20 . 
     Description of Configuration and Function of Vane Pump  1   
     The vane pump  1  is driven by, for example, power of an internal combustion engine of a vehicle, and is used as an oil pump that supplies a working oil as an example of a working fluid to fluid equipment such as a hydraulic power steering and a hydraulic continuously variable transmission. 
     The vane pump  1  shown in  FIG. 1  is a fixed capacity type vane pump. The vane pump  1  of this configuration example includes a housing  11 , a cover plate  12  that covers an opening of the housing  11 , and the pump unit  20  that is accommodated inside the housing  11  and the cover plate  12 . 
     As shown in  FIG. 2 , the housing  11  has an accommodation unit  11 A that has a shape of a concave portion and accommodates the pump unit  20 . The housing  11  has a suction inlet  43  that suctions the working oil from outside the apparatus, and a suction passage  42  that forms a passage, in the housing  11 , for the working oil suctioned from the suction inlet  43 . The suction passage  42  is disposed to face one end side suction port  60  and the other end side suction port  80  (described later) of a cam ring  30  (refer to  FIG. 3  described later). 
     Further, the housing  11  forms a high-pressure chamber  54 , in an innermost portion of the accommodation unit  11 A of the housing  11 , which is partitioned by an inner side plate  31  (described later) as shown in  FIG. 3 . 
     The cover plate  12  covers the opening of the accommodation unit  11 A of the housing  11  as shown in  FIG. 2 . The cover plate  12  and the housing  11  are fastened by a plurality of bolts  14  and are fixed. A seal plate  13  is pinched between the cover plate  12  and the housing  11 . The seal plate  13  covers and seals a plurality of passage grooves and concave portions formed in the housing  11  and the cover plate  12 . 
     Positioning pins  33 A and  33 B respectively pass through the cover plate  12  and the pump unit  20  to be mounted thereon and relative positioning of each of the members is performed in a circumferential direction. 
     The pump unit  20  has a rotation shaft  21 , a rotor  22  that is fixed to the rotation shaft  21 , a plurality of vanes  24  (refer to  FIGS. 3 and 4 ) that are slidably disposed in the rotor  22 , the cam ring  30  that surrounds the rotor  22  and the vanes  24 , and a pair of the inner side plate  31  and an outer side plate  32  that pinches the rotor  22 , the vanes  24 , and the cam ring  30  on both sides of the rotation shaft  21  in an axial direction. 
     The rotation shaft  21  is rotatably supported by a first bearing  15  that is disposed in the housing  11  and a second bearing  16  that is disposed in the cover plate  12 . A serration (not shown) is formed in the rotation shaft  21 , and the rotation shaft  21  is fixedly coupled with the rotor  22  via the serration. The rotor  22  rotates when the rotation shaft  21  receives driving from a driving source out of the vane pump  1  such as the internal combustion engine. 
     As shown in  FIG. 4 , the rotation shaft  21  (rotor  22 ) is configured to rotate in a D direction in  FIG. 4  in this configuration example. 
     As shown in  FIG. 4 , the rotor  22  is a member that has a circular outline, and has a plurality of concavities and convexities disposed on an outer circumferential surface thereof in this configuration example. Vane grooves  23  are formed at a plurality of positions of the rotor  22  in the circumferential direction. Herein, the outer circumferential surface of the rotor  22  is shaped to protrude toward a radially outer side at parts in the circumferential direction where the vane grooves  23  are formed and to be recessed toward a radially inner side between the two vane grooves  23  adjacent to each other in the circumferential direction. 
     The plurality of vane grooves  23  are disposed along the circumferential direction in an outer circumferential portion of the rotor  22 . Each of the vane grooves  23  is disposed along a radiation direction (radial direction). The vane grooves  23  are grooves open to the outer circumferential surface and both side surfaces of the rotor  22 . The vane groove  23  accommodates each of the vanes  24  and holds the accommodated vane  24  to be slidable in the radial direction. The vane groove  23  has a bottom portion space  23 A, which is wide in the circumferential direction, in a bottom portion (center side of the rotor  22 ). 
     The vanes  24  are plate-shaped members, and are mounted on the respective vane grooves  23  of the rotor  22  as described above. 
     Leading ends of the vanes  24  are pressed to and abut against an inner circumferential surface  30 C (described later) of the cam ring  30  due to pressure of a high-pressure discharge oil that is introduced to the bottom portion spaces  23 A of the vane grooves  23 . A mechanism that allows the vanes  24  to abut against the inner circumferential surface  30 C by using the pressure of the high-pressure discharge oil will be described in detail later. 
     When the rotor  22  rotates, the vanes  24  slide in the radial direction in the vane grooves  23 , and is repeatedly moved to be pushed out of the vane grooves  23  or to be pushed into the vane grooves  23 . In this case, during a single rotation of the rotor  22 , the vanes  24  are pushed most deeply into the vane grooves  23  when the vanes  24  are at a rotation angle directed from a discharge area (described later) to a suction area (described later). When the vanes  24  are at a rotation angle directed from the suction area to the discharge area, the vanes  24  are pushed most out of the vane grooves  23 . 
     As shown in  FIG. 4 , the cam ring  30  has a tubular shape, and has the inner circumferential surface  30 C that forms a cam surface with a cam curve which approximates an ellipse, and a circular outer circumferential surface  30 S. The cam ring  30  is disposed at a position where the outer circumferential surface  30 S faces the suction passage  42  formed in the housing  11 . 
     The cam ring  30  accommodates the rotor  22  and the vanes  24  in a tubular inner portion, that is, an area surround by the inner circumferential surface  30 C. An oil chamber Y is formed between the inner circumferential surface  30 C and the rotor  22 . Herein, the inner circumferential surface  30 C of the cam ring  30  is a surface approximating an ellipse as described above, and the rotor  22  has a circular outline. Accordingly, the oil chamber Y has an area with a wide gap in the axial direction between the inner circumferential surface  30 C and the outer circumferential surface of the rotor  22  and an area with a narrow gap in the axial direction between the inner circumferential surface  30 C and the outer circumferential surface of the rotor  22 . 
     As described above, the cam ring  30 , the rotor  22 , and the vanes  24  are pinched by the inner side plate  31  and the outer side plate  32  on both end sides in the axial direction. Each pump chamber  40  is formed by the inner side plate  31 , the outer side plate  32 , the inner circumferential surface  30 C of the cam ring  30 , the outer circumferential surface of the rotor  22 , and the two vanes  24  adjacent to each other. 
     A configuration and a function of the cam ring  30  will be described in detail later. With Regard to Inner Side Plate  31   
       FIG. 5  is an overall view of the inner side plate  31  of this configuration example.  FIG. 5  shows the inner side plate  31  viewed from an arrow V shown in  FIG. 2 . 
     The inner side plate  31 , which is an example of a side plate, is a member that has a disk-shaped outline as shown in  FIG. 5 , and has a shaft hole  31 A, through which the rotation shaft  21  (refer to  FIG. 4 ) passes, in a central portion. In addition, the inner side plate  31  has a suction port  41  and a high-pressure oil supply port  55  in an outer circumferential portion. The inner side plate  31  further has a high-pressure oil introduction port  56 A and a groove  56 B on a radially inner side compared to the suction port  41  and the high-pressure oil supply port  55  and in the vicinity of the shaft hole  31 A. 
     The inner side plate  31  is disposed in the accommodation unit  11 A of the housing  11  and is mounted to face one side portion of the cam ring  30  in the axial direction (refer to  FIGS. 2 and 3 ). 
     The suction port  41 , which is an example of a supply unit, is formed as a concave portion that is recessed in the axial direction in the outer circumferential portion of the inner side plate  31 . In this configuration example, the suction port  41  is configured to have a pair of first suction port  41 A and a second suction port  41 B that are arranged at two positions facing each other in a diametrical direction. The suction inlet  43  (refer to  FIG. 4 ) is allowed to communicate with the first suction port  41 A and the second suction port  41 B via the suction passage  42  (refer to  FIG. 4 ) that is disposed in the housing  11 . The first suction port  41 A and the second suction port  41 B form a path for the working oil supplied to the pump chamber  40  (refer to  FIG. 4 ) when the rotor  22  rotates. 
     Herein, the first suction port  41 A and the second suction port  41 B can be considered as parts where the outer circumferential surface of the inner side plate  31  is recessed to the radially inner side. 
     An inner side end portion  41 C, which is an end portion of the first suction port  41 A on the radially inner side, is formed to have an arc shape. Specifically, the inner side end portion  41 C is shaped to have an arc, which is smaller in radius than an outer circumferential circle of the inner side plate  31 , about a center position C2, which is a position shifted to the first suction port  41 A side from a center position C1 (corresponding to a rotation center of the rotor  22 ) of the outer circumferential circle of the inner side plate  31 . 
     An inner side end portion  41 D, which is an end portion of the second suction port  41 B positioned on the radially inner side of the rotation shaft  21 , is formed to have an arc shape. Specifically, the inner side end portion  41 D is shaped to have an arc, which is smaller in radius than the outer circumferential circle of the inner side plate  31 , about a center position C3, which is a position shifted to the second suction port  41 B side from the center position C1 of the inner side plate  31 . 
     The shapes of the inner side end portion  41 C and the inner side end portion  41 D can be considered as a part of an elliptical shape. 
     In a state where the inner side plate  31  is mounted on the cam ring  30 , each of the inner side end portion  41 C of the first suction port  41 A and the inner side end portion  41 D of the second suction port  41 B, which are examples of an outer circumference of the supply unit, has a shape that has a part along the inner circumferential surface  30 C of the cam ring  30 . In other words, each of the inner side end portion  41 C of the first suction port  41 A and the inner side end portion  41 D of the second suction port  41 B has a shape similar to the offset of the inner circumferential surface  30 C of the cam ring  30 . A relationship between the inner side end portion  41 C of the first suction port  41 A or the inner side end portion  41 D of the second suction port  41 B and the inner circumferential surface  30 C of the cam ring  30  will be described in detail later. 
     The high-pressure oil supply port  55  allows a discharge port  51  (described later) that is disposed in the outer side plate  32  to communicate with the high-pressure chamber  54 . The high-pressure oil supply port  55  constitutes a passage through which the working oil, which is discharged from the discharge port  51  of the outer side plate  32  when the rotor  22  rotates, is supplied to the high-pressure chamber  54 . 
     The high-pressure oil introduction port  56 A, which is formed to pass through the inner side plate  31 , is an arc-shaped groove about the center position C1. In this configuration example, the high-pressure oil introduction port  56 A is disposed at two positions opposing each other around the shaft hole  31 A on the same diameter of the inner side plate  31 . The high-pressure oil introduction port  56 A introduces the high-pressure discharge oil in the high-pressure chamber  54  to the bottom portion space  23 A (refer to  FIG. 4 ) of the vane groove  23  (refer to  FIG. 4 ). The high-pressure oil introduction port  56 A is set to communicate with the bottom portion space  23 A of the vane groove  23  no matter which rotation position the rotor  22  has. 
     The groove  56 B is an arc-shaped groove that is formed in the inner side plate  31 . In this configuration example, the groove  56 B is disposed at two positions pinched by the two high-pressure oil introduction ports  56 A formed in the inner side plate  31 . The grooves  56 B communicate with the bottom portion spaces  23 A (refer to  FIG. 4 ) of some of the vane grooves  23  (refer to  FIG. 4 ) in the circumferential direction of the rotor  22 . The grooves  56 B are set to communicate with the bottom portion spaces  23 A of the vane grooves  23  no matter with rotation position the rotor  22  has. 
     With Regard to Outer Side Plate  32   
       FIG. 6  is an overall view of the outer side plate  32  of this configuration example.  FIG. 6  shows the outer side plate  32  viewed from an arrow VI shown in  FIG. 2 . 
     The outer side plate  32 , which is an example of another side plate, is a member having a disk-shaped outline as shown in  FIG. 6 , and has a shaft hole  32 A, through which the rotation shaft  21  (refer to  FIG. 4 ) passes, in a central portion. In addition, the outer side plate  32  has a suction port  44  and the discharge port  51  in an outer circumferential portion. In addition, the outer side plate  32  has a back pressure groove  57  in the vicinity of the shaft hole  32 A. The outer side plate  32  further has groove portions T that communicate with the discharge port  51 . 
     The outer side plate  32  is disposed in the accommodation unit  11 A of the housing  11 , and is mounted to face a side portion of the cam ring  30  on the side opposite to the inner side plate  31  in the axial direction (refer to  FIGS. 2 and 3 ). 
     The suction port  44 , which is an example of another supply unit, is formed as an opening portion that is recessed to the radially inner side in an outer circumferential portion of the outer side plate  32 . In this configuration example, the suction port  44  is configured to have a pair of a first suction port  44 A and a second suction port  44 B that are arranged at two positions facing each other in the diametrical direction. The suction inlet  43  (refer to  FIG. 4 ) is allowed to communicate with the first suction port  44 A and the second suction port  44 B via the suction passage  42  (refer to  FIG. 4 ) that is disposed in the housing  11 . The first suction port  44 A and the second suction port  44 B form a path for the working oil toward the pump chamber  40  (refer to  FIG. 4 ) when the rotor  22  rotates. 
     An inner side end portion  44 C, which is an end portion of the first suction port  44 A on the radially inner side of the rotation shaft  21 , is formed to have an arc shape. Specifically, the inner side end portion  44 C is shaped to have an arc, which is smaller in radius than an outer circumferential circle of the outer side plate  32 , about a center position C5, which is a position shifted to the first suction port  44 A side from a center position C4 (corresponding to the rotation center of the rotor  22 ) of the outer circumferential circle of the outer side plate  32 . 
     An inner side end portion  44 D, which is an end portion of the second suction port  44 B on the radially inner side of the rotation shaft  21 , is formed to have an arc shape. Specifically, the inner side end portion  44 D is shaped to have an arc, which is smaller in radius than the outer circumferential circle of the outer side plate  32 , about a center position C6, which is a position shifted to the second suction port  44 B side from the center position C4 of the outer side plate  32 . 
     In a state where the outer side plate  32  is mounted on the cam ring  30 , each of the inner side end portion  44 C of the first suction port  44 A and the inner side end portion  44 D of the second suction port  44 B, which are examples of an outer circumference of the other supply unit, has a shape that has a part along the inner circumferential surface  30 C of the cam ring  30 . In other words, each of the inner side end portion  44 C of the first suction port  44 A and the inner side end portion  44 D of the second suction port  44 B has a shape similar to the offset of the inner circumferential surface  30 C of the cam ring  30 . A relationship between the inner side end portion  44 C of the first suction port  44 A or the inner side end portion  44 D of the second suction port  44 B and the inner circumferential surface  30 C of the cam ring  30  will be described in detail later. 
     The discharge port  51  is configured to have an opening that is formed to pass through the outer side plate  32 . In this configuration example, the discharge port  51  is configured to have a first discharge port  51 A and a second discharge port  51 B. The first discharge port  51 A and the second discharge port  51 B are allowed to communicate with a discharge outlet  53  (refer to  FIG. 4 ) of the vane pump  1  via a discharge passage  52  (refer to  FIG. 4 ) that is disposed in the cover plate  12  such that a discharge path for the working oil from the pump chamber  40  (refer to  FIG. 4 ) is formed when the rotor  22  rotates. 
     The back pressure groove  57  is a groove with an annular shape as shown in  FIG. 6 . The back pressure groove  57  is disposed to communicate with the bottom portion space  23 A of the vane, groove  23  no matter which rotation position the rotor  22  has. The back pressure groove  57  communicates with the bottom portion spaces  23 A of the entire vane grooves  23  of the rotor  22  (refer to  FIG. 4 ). Furthermore, the back pressure groove  57  communicates also with the high-pressure chamber  54  via the high-pressure oil introduction port  56 A (refer to  FIG. 3 ) of the inner side plate  31 . 
     As shown in  FIG. 6 , the groove portions T are grooves that communicate with the discharge port  51  formed in the outer side plate  32 . The groove portions T are positioned on a front side (upstream side) compared to each discharge port  51  (first discharge port  51 A and second discharge port  51 B) in a direction of rotation of the rotor  22 . 
     In the vane pump  1  to which this configuration example is applied, the groove portion T is disposed in the outer side plate  32 , and thus the pump chamber  40  (refer to  FIG. 4 ) reaches the groove portion T before reaching the discharge port  51  when the pump chamber  40  moves to the discharge port  51 . Also, an initiation point of communication between the pump chamber  40  and the discharge port  51  is configured to be earlier than in a case where the groove portion T is not provided. As such, in the vane pump  1  of this configuration example, the length of time of the communication between the pump chamber  40  and the discharge port  51  is longer than in a configuration where the groove portion T is not provided. As a result, in the vane pump  1  of this configuration example, a surge pressure in the pump chamber  40  is alleviated and generation of an abnormal noise is reduced. 
     With Regard to Cam Ring  30   
       FIGS. 7A to 7C  are views illustrating the cam ring  30  of this configuration example in detail. 
       FIG. 7A  is a side view of the cam ring  30 .  FIG. 7B  is a cross-sectional view of the cam ring  30  taken along line VIIb-VIIb of  FIG. 7A , and  FIG. 7C  is a cross-sectional view of the cam ring  30  taken along line VIIc-VIIc of  FIG. 7A . 
     The cam ring  30  shown in  FIG. 7A , which has a tubular shape, has the inner circumferential surface  30 C that forms the cam surface with the cam curve which approximate an ellipse as described above, and the circular outer circumferential surface  30 S. In addition, the cam ring  30  has one end side portion  30 A that has an annular shape in one side portion of the rotor  22  in the axial direction, and the other end side portion  30 B (refer to  FIG. 7B ) that has an annular shape in the other side portion. The cam ring  30  further has pin holes  30 H, through which a positioning pin  33 A and a positioning pin  33 B (refer to  FIG. 4 ) pass respectively. 
     With Regard to One End Side Portion  30 A 
     As shown in  FIG. 7A , the one end side suction port  60  that constitutes a suction path for the working oil toward the pump chamber  40  (refer to  FIG. 4 ) from the outer circumferential surface  30 S into the inner circumferential surface  30 C, and one end side discharge port  70  that constitutes the suction path for the working oil from the pump chamber  40  are formed in the one end side portion  30 A. 
     In this configuration example, the one end side suction port  60  is configured to have a first suction port  61  and a second suction port  62 . In addition, in this configuration example, the one end side discharge port  70  is configured to have a pair of a first discharge port  71  and a second discharge port  72 . 
     The first suction port  61  and the first discharge port  71  are one set and the second suction port  62  and the second discharge port  72  are one set, respectively fulfilling a series of operations of the suction of the working oil toward the pump chamber  40  and the discharge of the working oil from the pump chamber  40 . 
     In the following description, the first suction port  61  and the second suction port  62  are collectively referred to as the “one end side suction port  60 ” when not particularly distinguished, and the first discharge port  71  and the second discharge port  72  are collectively referred to as the “one end side discharge port  70 ” when not particularly distinguished. 
     With Regard to the Other End Side Portion  30 B 
     As shown in  FIGS. 7B and 7C , the other end side suction port  80  that constitutes a suction path for the working oil toward the pump chamber  40  (refer to  FIG. 4 ), and the other end side discharge port  90  that constitutes the discharge path for the working oil from the pump chamber  40  are formed in the other end side portion  30 B. 
     In this configuration example, the other end side suction port  80  is configured to have a first suction port  81  and a second suction port  82 . In addition, in this configuration example, the other end side discharge port  90  is configured to have a pair of a first discharge port  91  and a second discharge port  92 . 
     The first suction port  81  and the first discharge port  91  are one set and the second suction port  82  and the second discharge port  92  are one set, respectively fulfilling a series of operations of the suction of the working oil toward the pump chamber  40  and the discharge of the working oil from the pump chamber  40 . 
     In the following description, the first suction port  81  and the second suction port  82  are collectively referred to as the “other end side suction port  80 ” when not particularly distinguished, and the first discharge port  91  and the second discharge port  92  are collectively referred to as “the other end side discharge port  90 ” when not particularly distinguished. 
     The other end side suction port  80  is arranged in the other end side portion  30 B with the one end side suction port  60 , which is formed in the one end side portion  30 A, at front and back positions. Specifically, the first suction port  81  and the first suction port  61  are arranged at the front and back positions as shown in  FIG. 7C . In addition, the second suction port  82  and the second suction port  62  are arranged at the front and back positions as shown in  FIG. 7B . 
     In detail, the first suction port  81  and the first suction port  44 A face each other and the first suction port  61  and the second suction port  41 B face each other in a state where the cam ring  30  is pinched by the inner side plate  31  and the outer side plate  32 . Accordingly, the first suction port  44 A, the first suction port  81 , the first suction port  61 , and the second suction port  41 B have an overlapping positional relationship in the circumferential direction. 
     Likewise, the second suction port  82  and the second suction port  44 B face each other and the second suction port  62  and the first suction port  41 A face each other. Accordingly, the second suction port  44 B, the second suction port  82 , the second suction port  62 , and the first suction port  41 A have an overlapping positional relationship in the circumferential direction. 
     The other end side discharge port  90  is arranged in the other end side portion  30 B with the one end side discharge port  70 , which is formed in the one end side portion  30 A, at front and back positions. Specifically, the first discharge port  91  and the first discharge port  71  are arranged at the front and back positions as shown in  FIG. 7C . In addition, the second discharge port  92  and the second discharge port  72  are arranged at the front and back positions as shown in  FIG. 7B . 
     The one end side suction port  60  and the other end side suction port  80 , and the one end side discharge port  70  and the other end side discharge port  90  have the same shape although respectively formed surfaces differ in the other end side portion  30 B and the one end side portion  30 A. Accordingly, in the following description, the one end side suction port  60  and the one end side discharge port  70  will be described as representative examples, and description of the other end side suction port  80  and the other end side discharge port  90  will be omitted. 
     With Regard to Configuration and Function of One End Side Suction Port  60   
     The one end side suction port  60  (first suction port  61  and second suction port  62 ) is formed as a groove that is disposed to be open in the radial direction from the inner circumferential surface  30 C to the outer circumferential surface  30 S. The one end side suction port  60  is configured to have a bottom surface portion  601  and an inclined portion  602 . 
     The bottom surface portion  601  is a flat surface that is recessed in a thickness direction when compared to the other surface (hereinafter, referred to as a principal surface) of the one end side portion  30 A. The bottom surface portion  601  is formed to have an increasing width in the circumferential direction from the inner circumferential surface  30 C to the outer circumferential surface  30 S. 
     The inclined portion  602  is a surface that is inclined from the principal surface of the one end side portion  30 A toward the bottom surface portion  601 , and is disposed to extend from the inner circumferential surface  30 C toward the outer circumferential surface  30 S. Two inclined portions  602  are arranged to face each other in the circumferential direction. The facing inclined portions  602  are formed to have an increasing gap from the inner circumferential surface  30 C toward the outer circumferential surface  30 S. 
     Furthermore, the first suction port  61  and the second suction port  62  are disposed at positions facing each other in the diametrical direction through a center position C7 (corresponding to the rotation center of the rotor  22 ) of the cam ring  30 . In other words, a pair of the first suction port  61  and the second suction port  62  are arranged on a straight line through the center position C7 of the cam ring  30 . 
     In this configuration example, the pair of the first suction port  61  and the second suction port  62  are arranged in the diametrical direction. As such, an eccentric load that is applied to, for example, the rotation shaft  21  of the rotor  22  can be reduced. 
     As shown in  FIG. 7A , suction initiation positions  60   s  are formed in respective end portions of the first suction port  61  and the second suction port  62  on the upstream side in the direction of rotation (D direction in the drawing) of the rotor  22  (refer to  FIG. 4 ). In addition, suction completion positions  60   e  are formed in respective end portions of the first suction port  61  and the second suction port  62  on the downstream side in the direction of rotation of the rotor  22 . 
     The pump chambers  40  (refer to  FIG. 4 ) that are formed by the adjacent vanes  24  (refer to  FIG. 4 ) move in the first suction port  61  and the second suction port  62 . The suction of the working oil toward the pump chamber  40  is initiated when the vanes  24  forming the pump chamber  40  reach the suction initiation position  60   s . The suction of the working oil is completed when the pump chamber  40  passes through the suction completion position  60   e . Configuration and Function of One End Side Discharge Port  70   
     As shown in  FIG. 7A , the one end side discharge port  70  is formed as a groove that is disposed to be open only to the inner circumferential surface  30 C side. The one end side discharge port  70  is configured to have a bottom surface portion  701 , an inclined portion  702 , and a through-hole  703 . 
     The bottom surface portion  701  is a flat surface that is recessed in the thickness direction when compared to the principal surface of the one end side portion  30 A. 
     The inclined portion  702  is a surface that is inclined from the principal surface of the one end side portion  30 A toward the bottom surface portion  701 , and is disposed to extend from the inner circumferential surface  30 C toward the outer circumferential surface  30 S. Two inclined portions  702  are arranged to face each other in the circumferential direction. 
     The through-hole  703  is formed in the bottom surface portion  701  and passes through to the other end side discharge port  90 . As such, the discharge oil is allowed to communicate with the one end side portion  30 A and the other end side portion  30 B of the cam ring  30  therebetween. 
     As shown in  FIG. 7A , in the first discharge port  71  and the second discharge port  72 , discharge initiation positions  70   s  are formed in respective end portions of the first discharge port  71  and the second discharge port  72  on the upstream side in the direction of rotation (D direction in the drawing) of the rotor  22  (refer to  FIG. 4 ). In addition, discharge completion positions  70   e  are formed in respective end portions of the first discharge port  71  and the second discharge port  72  on the downstream side in the direction of rotation of the rotor  22 . 
     The pump chambers  40  (refer to  FIG. 4 ) that are formed by the adjacent vanes  24  (refer to  FIG. 4 ) move in the first discharge port  71  and the second discharge port  72 . The discharge of the working oil from the pump chamber  40  is initiated when the vanes  24  forming the pump chamber  40  reach the discharge initiation positions  70   s . The discharge of the working oil is completed when the pump chamber  40  passes through the discharge completion positions  70   e.    
     The second suction port  62  of the one end side suction port  60  that has the above-described configuration is disposed along a flow path part of the suction passage  42  that extends toward the second suction port  62 . In other words, in this configuration example, the flow path part that extends from the suction passage  42  toward the second suction port  62  and the second suction port  62  are arranged to have a consistent main flow direction of the working oil and are arranged to have angles matching with each other. In this manner, in this configuration example, the working oil that flows through the suction passage  42  flows straightforwardly into the second suction port  62 . As such, in this configuration example, the working oil flows to the second suction port  62  efficiently. 
     Operation of Vane Pump  1   
     In the vane pump  1  that has the above-described configuration, the rotor  22  rotates when the rotation shaft  21  rotates by receiving the driving from, for example, the internal combustion engine (not shown) as shown in  FIG. 4 . When the rotor  22  rotates, the leading ends of the plurality of vanes  24  are in a rotating state while being pressed to the inner circumferential surface  30 C on an inner circumference of the cam ring  30 . 
     Herein, in the vane pump  1 , the working oil that is supplied from the suction inlet  43  is in a state of flowing into the one end side suction port  60  and the other end side suction port  80  of the cam ring  30  via the suction passage  42 . Then, in the suction area on the upstream side in the direction of rotation of the rotor  22 , the working oil from the suction port  41  of the inner side plate  31  and the suction port  44  of the outer side plate  32  is suctioned to the pump chamber  40  that expands when the rotor  22  rotates. The suction area refers to an area where the suction port  41  of the inner side plate  31  and the suction port  44  of the outer side plate  32  are disposed in the circumferential direction. 
     In the discharge area on the downstream side in the direction of rotation of the rotor  22 , the working oil from the pump chamber  40  that is compressed when the rotor  22  rotates is discharged to the discharge port  51 . The high-pressure discharge oil that is discharged to the discharge port  51  is discharged from the discharge outlet  53  through the discharge passage  52 . The discharge area refers to an area where the discharge port  51  of the outer side plate  32  is disposed in the circumferential direction. 
     The vane pump  1  to which this configuration example is applied fulfills a pump operation in the above-described manner such that the working oil suctioned by the suction inlet  43  is discharged from the discharge outlet  53 . 
     Next, an abutting operation of the inner circumferential surface  30 C of the vane  24  of the vane pump  1  according to this configuration example will be descried. 
     As shown in  FIG. 3 , the high-pressure discharge oil that is discharged from the discharge port  51  due to the rotation of the rotor  22  is supplied to the high-pressure chamber  54  through the bottom portion spaces  23 A of some of the vane grooves  23  of the rotor  22  and the high-pressure oil supply port  55 . Furthermore, the high-pressure discharge oil with which the high-pressure chamber  54  is filled is supplied to the annular back pressure groove  57  of the outer side plate  32  via the high-pressure oil introduction port  56 A of the inner side plate  31  and the bottom portion spaces  23 A of some of the vane grooves  23  of the rotor  22 . 
     The high-pressure discharge oil that is introduced to the bottom portion spaces  23 A of the vane grooves  23  which do not communicate with the high-pressure oil introduction port  56 A of the inner side plate  31  is pushed to fill the groove  56 B of the inner side plate  31 . 
     The high-pressure discharge oil that is supplied to the annular back pressure groove  57  is in a state of being introduced at the same time to the bottom portion spaces  23 A of the entire vane grooves  23  of the rotor  22  with which the back pressure groove  57  communicates. The leading ends of the vanes  24  are pressed to the inner circumferential surface  30 C of the cam ring  30  due to the pressure of the high-pressure discharge oil which is introduced to the bottom portion spaces  23 A of the vane grooves  23 . 
     Operation of Vane  24  in Vicinity of Suction Port  41   
       FIG. 8  is a view illustrating an operation of the vane  24  in the vicinity of the suction port  41  of this configuration example. 
     As described above, the first suction port  41 A and the second suction port  41 B of the suction port  41  of the inner side plate  31  have the same shape. In the following description, the operation of the vane  24  in the vicinity of the second suction port  41 B will be described as a representative example, and description of the operation of the vane  24  in the vicinity of the first suction port  41 A will be omitted. 
     As shown in  FIG. 8 , the inner side end portion  41 D of the second suction port  41 B is shaped along the inner circumferential surface  30 C of the cam ring  30 . Accordingly, the distance (length in the radial direction) between the inner side end portion  41 D of the second suction port  41 B and the inner circumferential surface  30 C of the cam ring  30  is constant in the suction area. In other words, an opening with a constant width in the radial direction is formed between the inner side end portion  41 D and the inner circumferential surface  30 C of the cam ring  30 . As such, a period when the length (refer to a length L1) of a part where the vane  24  protrudes from the inner side plate  31  (inner side end portion  41 D) to the radially outer side is constant is present when the vane  24  that rotates when the rotor  22  rotates passes through the suction area. Accordingly, inclination of the vane  24  with respect to the rotation shaft  21  of the rotor  22  is suppressed (described in detail later). 
     Herein, the second suction port  41 B of the example that is shown can be considered to have a shape in which the area where the length of the part where the vane  24  protrudes from the inner side plate  31  to the radially inner side is constant is formed. 
     In addition, the second suction port  41 B of the example that is shown can be considered that the upstream side part of the inner side end portion  41 D in the direction of the rotation (D direction in the drawing) of the rotor  22  (refer to  FIG. 4 ) is shaped along the inner circumferential surface  30 C of the cam ring  30 . 
     Furthermore, the second suction port  41 B of the example that is shown can be considered that the part of the inner side end portion  41 D that faces the first suction port  61  of the cam ring  30  is shaped along the inner circumferential surface  30 C of the cam ring  30 . In further detail, a part of the inner side end portion  41 D of the second suction port  41 B overlapping with the area where the bottom surface portion  601  of the first suction port  61  is formed in the circumferential direction can be considered to be shaped along the inner circumferential surface  30 C of the cam ring  30 . 
     Operation of Vane  24  in Vicinity of Suction Port  44   
       FIG. 9  is a view illustrating the operation of the vane  24  in the vicinity of the suction port  44  of this configuration example. 
     As described above, the first suction port  44 A and the second suction port  44 B of the suction port  44  of the outer side plate  32  have the same shape. In the following description, the operation of the vane  24  in the vicinity of the first suction port  44 A will be described as a representative example, and description of the operation of the vane  24  in the vicinity of the second suction port  44 B will be omitted. 
     As shown in  FIG. 9 , the inner side end portion  44 C of the first suction port  44 A is shaped along the inner circumferential surface  30 C of the cam ring  30 . Accordingly, the distance (length in the radial direction) between the inner side end portion  44 C of the first suction port  44 A and the inner circumferential surface  30 C of the cam ring  30  is constant in the suction area. In other words, an opening with a constant width in the radial direction is formed between the inner side end portion  44 C and the inner circumferential surface  30 C of the cam ring  30 . As such a period when the length (refer to a length L3) of a part where the vane  24  protrudes from the outer side plate  32  (inner side end portion  44 C) to the radially outer side is constant is present when the vane  24  that rotates when the rotor  22  rotates passes through the suction area. Accordingly, inclination of the vane  24  with respect to the rotation shaft  21  of the rotor  22  is suppressed (described in detail later). 
     Herein, the first suction port  44 A of the example that is shown can be considered to have a shape in which the area where the length of the part where the vane  24  protrudes from the outer side plate  32  to the radially outer side is constant is formed. 
     In addition, the first suction port  44 A of the example that is shown can be considered that the upstream side part of the inner side end portion  44 C in the direction of the rotation (D direction in the drawing) of the rotor  22  (refer to  FIG. 4 ) is shaped along the inner circumferential surface  30 C of the cam ring  30 . 
     Furthermore, the first suction port  44 A of the example that is shown can be considered that the part of the inner side end portion  44 C that faces the first suction port  81  of the cam ring  30  is shaped along the inner circumferential surface  30 C of the cam ring  30 . In further detail, a part of the inner side end portion  44 C of the first suction port  44 A overlapping with the area where a bottom surface portion  801  of the first suction port  81  is formed in the circumferential direction can be considered to be shaped along the inner circumferential surface  30 C of the cam ring  30 . 
     Inclination of Vane  24   
       FIG. 10  is a view illustrating the inclination of the vane  24  of this configuration example. In further detail,  FIG. 10  shows an area in the circle shown in  FIG. 3 . 
     A configuration in which the inner side end portion  41 D of the second suction port  41 B or the inner side end portion  44 C of the first suction port  44 A is placed closer to the rotation shaft  21  side of the rotor  22  to increase a suction area where the working oil is suctioned can be considered in a case where the efficiency of the suction of the working oil is to be increased in the vane pump  1 . However, when the inner side end portion  41 D of the second suction port  41 B or the inner side end portion  44 C of the first suction port  44 A is simply placed closer to the rotation shaft  21  side of the rotor  22 , the durability of the vane pump  1  may be deteriorated. Herein, the efficiency of the suction simply refers to the amount (volume) of the working oil that passes through the suction port  41  per hour. 
     Describing specifically with reference to  FIG. 10 , the suction area where the working oil is suctioned increases and the efficiency of the suction increases as the inner side end portion  41 D and the inner side end portion  44 C are moved to the rotation shaft  21  (refer to  FIG. 4 ) of the rotor  22 , that is, the lower side in  FIG. 10 . However, when the inner side end portion  41 D and the inner side end portion  44 C are moved to the lower side in the drawing, the length (refer to the length L1 in  FIG. 8  and the length L3 in  FIG. 9 ) of the part where the vane  24  protrudes from the inner side plate  31  or the outer side plate  32  to the radially outer side (upper side in the drawing) increases. As the length of the protruding part increases, the length (refer to a length L2 in  FIG. 8  and a length L4 in  FIG. 9 ) of the area where the vane  24  is supported by the inner side plate  31  or the outer side plate  32  decreases. As a result, the vane  24  is likely to be inclined with respect to the rotation shaft  21  of the rotor  22 . 
     Accordingly, a corner of the vane  24 , which is a plate-shaped member, is more likely to abut against the inner side plate  31  or the outer side plate  32  than in a case where, for example, radial positions of the inner side end portion  41 D and the inner side end portion  44 C are positioned outside (refer to an inner side end portion  410 D and an inner side end portion  440 C shown by the dashed lines in the drawing). This, for example, may result in damage (burning) to the inner side plate  31  or the outer side plate  32  and the generation of the abnormal noise. Alternatively, the inner side plate  31  or the outer side plate  32  is likely to be worn, and the durability of the vane pump  1  may be deteriorated. 
     In this configuration example, the positions of the inner side end portion  41 D and the inner side end portion  44 C are determined such that the vane  24  protrudes from the inner side plate  31  or the outer side plate  32  by less than half of the length in the radial direction. In detail, the length L1 in  FIG. 8  is smaller than the length L2, or the length L3 in  FIG. 9  is smaller than the length L4. More preferably, the positions of the inner side end portion  41 D and the inner side end portion  44 C are determined such that the vane  24  protrudes from the inner side plate  31  or the outer side plate  32  by less than four-tenths of the length in the radial direction. 
     In this configuration example described above, the length at which the vane  24  protrudes from the inner side plate  31  or the outer side plate  32  to the radially outer side is constant when the rotor  22  rotates to cause the vane  24  to pass through the suction area. In other words, the vane  24  and the inner side plate  31  or the outer side plate  32  have constant relative positions. As such, the position of the vane  24 , which is likely to have an unstable posture when passing through the suction area to suction the working oil, is not shifted with respect to the positions of the inner side plate  31  or the outer side plate  32 , and the inclination of the vane  24  in response to an external force from the inner side plate  31  or the outer side plate  32  is suppressed. 
     Another Configuration Example 
       FIG. 11  is an overall view of an inner side plate  310  of another configuration example. 
     In the following description, the same reference numerals are used in the parts that are identical to those of the inner side plate  31  shown in  FIG. 5 , and detailed description thereof will be omitted. 
     In the above description, the high-pressure oil introduction port  56 A is an arc-shaped groove about the center position C1 which is formed through the inner side plate  31 . 
     In contrast, according to a high-pressure oil introduction port (through-hole)  560 A shown in  FIG. 11 , a radially outer side end portion  560 B, which is an end portion of the rotation shaft  21  positioned on the radially outer side, is shaped along the inner side end portion  41 C of the first suction port  41 A (inner side end portion  41 D of the second suction port  41 B). In detail, the radially outer side end portion  560 B of the high-pressure oil introduction port  560 A is shaped along the inner circumferential surface  30 C of the cam ring  30 . In this manner, the distance (length in the radial direction, refer to the arrow in the drawing) between the radially outer side end portion  560 B and the inner side end portion  41 C of the first suction port  41 A (inner side end portion  41 D of the second suction port  41 B) is constant. 
     Herein, the pressure of the working oil in the high-pressure oil introduction port  560 A where the high-pressure discharge oil introduced is higher than the pressure of the working oil in the first suction port  41 A. Accordingly, when the distance between the radially outer side end portion  560 B and the inner side end portion  41 C of the first suction port  41 A (inner side end portion  41 D of the second suction port  41 B) decreases, the working oil may flow (leak) from the high-pressure oil introduction port  560 A toward the first suction port  41 A. 
     In this configuration example, the radially outer side end portion  560 B of the high-pressure oil introduction port  560 A is shaped along the inner side end portion  41 C of the first suction port  41 A (inner side end portion  41 D of the second suction port  41 B). Accordingly, when compared to a case in which this configuration is not adopted, the leak of the working oil from the high-pressure oil introduction port  560 A into the first suction port  41 A is suppressed. 
     In detail, in this configuration example, an area between the high-pressure oil introduction port  560 A and the inner side end portion  41 C of the first suction port  41 A (inner side end portion  41 D of the second suction port  41 B), that is, an area where the working oil is sealed between the high-pressure oil introduction port  560 A and the first suction port  41 A has a constant width. The amount of leak of the working oil can be adjusted by determining the width of the area, and the design of the inner side plate  310  is facilitated with the configuration of this configuration example. 
     Modification Example 
     In the above description, each of the inner side end portion  41 C and the inner side end portion  41 D of the inner side plate  31  and the inner side end portion  44 C and the inner side end portion  44 D of the outer side plate  32  are shaped along the inner circumferential surface  30 C of the cam ring  30 . However, any one of the inner side end portion  41 C, the inner side end portion  41 D, the inner side end portion  44 C, and the inner side end portion  44 D may be shaped along the inner circumferential surface  30 C of the cam ring  30 . 
     For example, the inner side end portion  41 C and the inner side end portion  41 D of the inner side plate  31  may be shaped along the inner circumferential surface  30 C of the cam ring  30  and the inner side end portion  44 C and the inner side end portion  44 D of the outer side plate  32  may be shaped along the arc about the center position C4 of the outer side plate  32 . 
     In addition, the inner side end portion  44 C and the inner side end portion  44 D of the outer side plate  32  may be shaped along the inner circumferential surface  30 C of the cam ring  30  and the inner side end portion  41 C and the inner side end portion  41 D of the inner side plate  31  may be shaped along the arc about the center position C1 of the inner side plate  31 . 
     In the above description, the groove portion T is disposed in the outer side plate  32 . However, the groove portion T may be disposed in the inner side plate  31 , and the groove portion T may be disposed in each of the inner side plate  31  and the outer side plate  32 .