Variable displacement vane pump

Abstract

A variable displacement vane pump, including a pump body, a driving shaft, a rotor, a cam ring swingable on a swing support surface, first and second plate members on opposite sides of the cam ring, a suction port and a discharge port on a side of at least one of the first and second plate members, a seal cooperating with the swing support surface to divide a space on an outer circumferential side of the cam ring into first and second fluid pressure chambers, a fluid pressure control valve, a stop disposed on the pump body on a side of the first fluid pressure chamber and restricting a swing movement of the cam ring, and a detent disposed between the cam ring and the pump body on a side of the second fluid pressure chamber and preventing a rotational movement of the cam ring around the driving shaft.

1 . A variable displacement vane pump, comprising:
 a pump body;   a driving shaft supported on the pump body;   a rotor which is disposed within the pump body and rotatably driven by the driving shaft, the rotor being formed with a plurality of slots which are spaced from each other in a circumferential direction of the rotor,   a plurality of vanes which are fitted into the slots so as to be moveable out from the slots and into the slots in a radial direction of the rotor;   an annular cam ring disposed within the pump body so as to be swingable on a swing support surface, the cam ring cooperating with the rotor and the vanes to define a plurality of pump chambers on an inner circumferential side of the cam ring;   a first plate member and a second plate member which are disposed on opposite sides of the cam ring in an axial direction of the cam ring, respectively;   a suction port and a discharge port which are disposed on a side of at least one of the first and second plate members, the suction port being opened to a suction region in which volumes of the pump chambers are increased with the rotation of the rotor, the discharge port being opened to a discharge region in which the volumes of the pump chambers are decreased with the rotation of the rotor;   a seal cooperating with the swing support surface to divide a space on an outer circumferential side of the cam ring into a first fluid pressure chamber and a second fluid pressure chamber which are disposed between the seal and the swing support surface, the first fluid pressure chamber being disposed in one swing direction of the cam ring in which the cam ring is swung to cause increase in a flow rate of a working fluid which is discharged from the discharge port, the second fluid pressure chamber being disposed in the other swing direction of the cam ring in which the cam ring is swung to cause decrease in the flow rate of the working fluid which is discharged from the discharge port;   a stop disposed on the pump body on a side of the first fluid pressure chamber, the stop restricting a swing movement of the cam ring in the one swing direction of the cam ring;   a control valve controlling a fluid pressure which is introduced into the first fluid pressure chamber or the second fluid pressure chamber; and   a detent disposed between the cam ring and the pump body on a side of the second fluid pressure chamber, the detent preventing a rotational movement of the cam ring around the driving shaft.   
   
   
       2 . The variable displacement vane pump as claimed in  claim 1 , wherein the detent comprises a recessed portion which is formed on an outer circumferential surface of the cam ring and a pin which is disposed between the recessed portion and the pump body so as to be engaged in the recessed portion. 
   
   
       3 . The variable displacement vane pump as claimed in  claim 2 , wherein the control valve controls the fluid pressure which is introduced into the first fluid pressure chamber, and the second fluid pressure chamber receives at least a suction pressure which is sucked from the suction port. 
   
   
       4 . The variable displacement vane pump as claimed in  claim 3 , wherein the second plate member is a pressure plate disposed between the pump body and the cam ring and biased toward the cam ring by a discharge pressure which is discharged from the discharge port, the pressure plate being formed with a pin holding hole which holds the pin and extends through the pressure plate in the axial direction of the cam ring. 
   
   
       5 . The variable displacement vane pump as claimed in  claim 4 , wherein the pump body is formed with a pin holding hole, the pin holding hole holding an axial end portion of the pin which penetrates through and projects from the pressure plate. 
   
   
       6 . The variable displacement vane pump as claimed in  claim 5 , wherein the pin holding hole of the pump body has an elliptic shape elongated in a radial direction of the pin. 
   
   
       7 . The variable displacement vane pump as claimed in  claim 3 , wherein the pin is disposed near the swing support surface. 
   
   
       8 . The variable displacement vane pump as claimed in  claim 7 , further comprising a low fluid pressure supply passage which is opened to the second fluid pressure chamber and introduces the suction pressure into the second fluid pressure chamber, the low fluid pressure supply passage being disposed on a side of the seal apart from the pin in a circumferential direction of the cam ring. 
   
   
       9 . The variable displacement vane pump as claimed in  claim 2 , wherein the cam ring comprises a pin holding groove which is formed on an outer circumferential surface of the cam ring and holds the pin, the pin holding groove being so arranged as to form a clearance between the pin holding groove and the pin when the cam ring is placed in a maximum eccentric position relative to the driving shaft in the one swing direction. 
   
   
       10 . The variable displacement vane pump as claimed in  claim 1 , wherein the control valve controls the fluid pressure to be introduced in the first fluid pressure chamber, and the second fluid pressure chamber receives at least a suction pressure which is sucked from the suction port. 
   
   
       11 . The variable displacement vane pump as claimed in  claim 10 , wherein the detent comprises a recessed portion which is formed on an outer circumferential surface of the cam ring, and a pin which is disposed between the recessed portion and the pump body so as to be engaged in the recessed portion. 
   
   
       12 . The variable displacement vane pump as claimed in  claim 1 , wherein the pump body comprises a plate member which forms the swing support surface, the plate member being made of a material which has a hardness higher than that of the pump body. 
   
   
       13 . The variable displacement vane pump as claimed in  claim 12 , wherein the detent comprises a pin holding groove which is formed on an inner circumferential surface of the pump body and a pin which is held in the pin holding groove, the plate member is held in a plate holding groove which is formed on the inner circumferential surface of the pump body, and the pin holding groove and the plate holding groove are spaced apart from each other in a circumferential direction of the pump body. 
   
   
       14 . The variable displacement vane pump as claimed in  claim 1 , wherein the seal and the swing support surface are disposed in substantially diametrically opposed relation to each other in a radial direction of the cam ring. 
   
   
       15 . The variable displacement vane pump as claimed in  claim 1 , wherein the detent comprises a projection which is disposed on an outer circumferential surface of the cam ring, and a recessed portion which is disposed on an inner circumferential surface of the pump body so as to be engaged with the projection. 
   
   
       16 . The variable displacement vane pump as claimed in  claim 1 , further comprising a plunger which is disposed on the pump body so as to be opposed to an outer circumferential surface of the cam ring on a side of the second fluid pressure chamber and moveable in a radial direction of the cam ring, and a biasing member which biases the plunger toward the cam ring, wherein the detent comprises a tip end portion of the plunger and a support portion which is disposed on the outer circumferential surface of the cam ring and supports the tip end portion of the plunger. 
   
   
       17 . A variable displacement vane pump, comprising:
 a pump body;   a driving shaft supported on the pump body;   a rotor disposed within the pump body and rotatably driven by the driving shaft, the rotor being formed with a plurality of slots which are spaced from each other in a circumferential direction of the rotor,   a plurality of vanes which are fitted into the slots so as to be moveable out from the slots and into the slots in a radial direction of the rotor;   an annular cam ring disposed within the pump body so as to be swingable on a swing support surface, the cam ring cooperating with the rotor and the vanes to define a plurality of pump chambers on an inner circumferential side of the cam ring;   a first plate member and a second plate member which are disposed on opposite sides of the cam ring in an axial direction of the cam ring, respectively;   a suction port and a discharge port which are disposed on a side of at least one of the first and second plate members, the suction port being opened to a suction region in which volumes of the pump chambers are increased with the rotation of the rotor, the discharge port being opened to a discharge region in which the volumes of the pump chambers are decreased with the rotation of the rotor;   a seal cooperating with the swing support surface to divide a space on an outer circumferential side of the cam ring into a first fluid pressure chamber and a second fluid pressure chamber which are disposed between the seal and the swing support surface, the first fluid pressure chamber being disposed in one swing direction of the cam ring in which the cam ring is swung to cause increase in a flow rate of a working fluid which is discharged from the discharge port, the second fluid pressure chamber being disposed in the other swing direction of the cam ring in which the cam ring is swung to cause decrease in the flow rate of the working fluid which is discharged from the discharge port;   a stop disposed on the pump body on a side of the first fluid pressure chamber, the stop restricting a swing movement of the cam ring in the one swing direction of the cam ring;   a control valve controlling a fluid pressure which is introduced into the first fluid pressure chamber or the second fluid pressure chamber; and   a detent including a projection which is disposed on an outer circumferential surface of the cam ring, and a recessed portion which is disposed on an inner circumferential surface of the pump body on a side of the first fluid pressure chamber so as to be engaged with the projection, the detent preventing a rotational movement of the cam ring around the driving shaft with engagement of the projection and the recessed portion.   
   
   
       18 . The variable displacement vane pump as claimed in  claim 17 , wherein the projection of the cam ring is integrally formed with the cam ring. 
   
   
       19 . A variable displacement vane pump, comprising:
 a pump body;   a driving shaft supported on the pump body;   a rotor disposed within the pump body and rotatably driven by the driving shaft, the rotor being formed with a plurality of slots which are spaced from each other in a circumferential direction of the rotor,   a plurality of vanes which are fitted into the slots so as to be moveable out from the slots and into the slots in a radial direction of the rotor;   an annular cam ring disposed within the pump body so as to be swingable on a swing support surface, the cam ring cooperating with the rotor and the vanes to define a plurality of pump chambers on an inner circumferential side of the cam ring;   a first plate member and a second plate member which are disposed on opposite sides of the cam ring in an axial direction of the cam ring, respectively;   a suction port and a discharge port which are disposed on a side of at least one of the first and second plate members, the suction port being opened to a suction region in which volumes of the pump chambers are increased with the rotation of the rotor, the discharge port being opened to a discharge region in which the volumes of the pump chambers are decreased with the rotation of the rotor;   a seal cooperating with the swing support surface to divide a space on an outer circumferential side the cam ring into a first fluid pressure chamber and a second fluid pressure chamber which are disposed between the seal and the swing support surface, the first fluid pressure chamber being disposed in one swing direction of the cam ring in which the cam ring is swung to cause increase in a flow rate of a working fluid which is discharged from the discharge port, the second fluid pressure chamber being disposed in the other swing direction of the cam ring in which the cam ring is swung to cause decrease in the flow rate of the working fluid which is discharged from the discharge port;   a stop disposed on the pump body on a side of the first fluid pressure chamber, the stop restricting a swing movement of the cam ring in the one swing direction of the cam ring;   a control valve controlling a fluid pressure which is introduced into the first fluid pressure chamber or the second fluid pressure chamber; and   a detent including a projection which is disposed on an end surface of the cam ring in an axial direction of the cam ring, and a recessed portion which is disposed on one of the first plate member and the second plate member so as to be engaged with the projection, the detent preventing a rotational movement of the cam ring around the driving shaft with engagement of the projection and the recessed portion.   
   
   
       20 . The variable displacement vane pump as claimed in  claim 19 , wherein the cam ring is formed with a through-hole which extends through the cam ring in an axial direction of the cam ring, and the projection of the cam ring is formed by an end portion of a pin that is inserted into the through-hole. 
   
   
       21 . The variable displacement vane pump as claimed in  claim 19 , wherein the projection of the cam ring is integrally formed with the cam ring. 
   
   
       22 . A variable displacement vane pump, comprising:
 a pump body;   a driving shaft supported on the pump body;   a rotor disposed within the pump body and rotatably driven by the driving shaft, the rotor being formed with a plurality of slots which are spaced from each other in a circumferential direction of the rotor,   a plurality of vanes which are fitted into the slots so as to be moveable out from the slots and into the slots in a radial direction of the rotor;   an annular cam ring disposed within the pump body so as to be swingable on a swing support surface, the cam ring cooperating with the rotor and the vanes to define a plurality of pump chambers on an inner circumferential side of the cam ring;   a first plate member and a second plate member which are disposed on opposite sides of the cam ring in an axial direction of the cam ring, respectively;   a suction port and a discharge port which are disposed on a side of at least one of the first and second plate members, the suction port being opened to a suction region in which volumes of the pump chambers are increased with the rotation of the rotor, the discharge port being opened to a discharge region in which the volumes of the pump chambers are decreased with the rotation of the rotor;   a seal cooperating with the swing support surface to divide a space on an outer circumferential side the cam ring into a first fluid pressure chamber and a second fluid pressure chamber which are disposed between the seal and the swing support surface, the first fluid pressure chamber being disposed in one swing direction of the cam ring in which the cam ring is swung to cause increase in a flow rate of a working fluid which is discharged from the discharge port, the second fluid pressure chamber being disposed in the other swing direction of the cam ring in which the cam ring is swung to cause decrease in the flow rate of the working fluid which is discharged from the discharge port;   a stop disposed on the pump body on a side of the first fluid pressure chamber, the stop restricting a swing movement of the cam ring in the one swing direction of the cam ring;   a control valve controlling a fluid pressure which is introduced into the first fluid pressure chamber or the second fluid pressure chamber; and   a detent including a first meshing portion which is disposed on an outer circumferential surface of the cam ring and a second meshing portion which is disposed on an inner circumferential surface of the pump body and always in meshing engagement with the first meshing portion, the first meshing portion and the second meshing portion being formed with a plurality of convexes and concaves, respectively, the detent preventing a rotational movement of the cam ring around the driving shaft by keeping the meshing engagement of the convexes and concaves of the first meshing portion and the convexes and concaves of the second meshing portion.   
   
   
       23 . A variable displacement vane pump, comprising:
 a pump body;   a driving shaft supported on the pump body;   a rotor disposed within the pump body and rotatably driven by the driving shaft, the rotor being formed with a plurality of slots which are spaced from each other in a circumferential direction of the rotor,   a plurality of vanes which are fitted into the slots so as to be moveable out from the slots and into the slots in a radial direction of the rotor;   an annular cam ring disposed within the pump body so as to be swingable on a swing support surface, the cam ring cooperating with the rotor and the vanes to define a plurality of pump chambers on an inner circumferential side of the cam ring;   a first plate member and a second plate member which are disposed on opposite sides of the cam ring in an axial direction of the cam ring, respectively;   a suction port and a discharge port which are disposed on a side of at least one of the first and second plate members, the suction port being opened to a suction region in which volumes of the pump chambers are increased with the rotation of the rotor, the discharge port being opened to a discharge region in which the volumes of the pump chambers are decreased with the rotation of the rotor;   a seal cooperating with the swing support surface to divide a space on an outer circumferential side the cam ring into a first fluid pressure chamber and a second fluid pressure chamber which are disposed between the seal and the swing support surface, the first fluid pressure chamber being disposed in one swing direction of the cam ring in which the cam ring is swung to cause increase in a flow rate of a working fluid which is discharged from the discharge port, the second fluid pressure chamber being disposed in the other swing direction of the cam ring in which the cam ring is swung to cause decrease in the flow rate of the working fluid which is discharged from the discharge port;   a stop disposed on the pump body on a side of the first fluid pressure chamber, the stop restricting a swing movement of the cam ring in the one swing direction of the cam ring;   a control valve controlling a fluid pressure which is introduced into the first fluid pressure chamber or the second fluid pressure chamber; and   a detent including a recessed portion which is disposed on an end surface of the cam ring in an axial direction of the cam ring and disposed on a side of the second fluid pressure chamber, and a projection which is disposed on one of the first plate member and the second plate member and engaged in the recessed portion, the detent preventing a rotational movement of the cam ring around the driving shaft with engagement of the recessed portion and the projection.