Variable capacity vane pump

Abstract

Variable capacity vane pump 1 supplying working fluid to power steering device of vehicle has pump housing 2 formed from bottomed cylindrical-shaped front housing 5 and rear housing 6 closing the front housing, pump element 3 accommodated in pump housing, communicating with inlet passage 23 and with outlet passage 30 and sucking and discharging working fluid, and flow amount control valve 33 controlling an amount of working fluid discharged by pump element. Pressure-sensitive valve 50, which changes a flow passage cross-sectional area of the outlet passage so that the discharge amount of the pump element is increased with increase in load pressure of power steering device, is set at some midpoint of the outlet passage and at bottom wall portion 5 b of front housing. It is therefore possible to suppress increase in size of device while reducing energy loss when variable capacity vane pump is mounted in power steering device.

1 . A variable capacity vane pump supplying working fluid to a power steering device of a vehicle, comprising:
 a pump housing formed from a first housing having a cylindrical portion and a bottom wall portion provided so as to close one end opening of the cylindrical portion and a second housing provided so as to close the other end opening of the cylindrical portion, the pump housing forming a pump element accommodation space inside the pump housing between the first and second housings;   a drive shaft inserted and rotatably supported in the pump housing;   a rotor accommodated in the pump element accommodation space and driven and rotated by the drive shaft, the rotor being provided with a plurality of slits in a radial direction of the rotor;   vanes provided in the slits so as to extend and retract;   a ring-shaped cam ring movably provided in the pump element accommodation space and forming a plurality of pump chambers together with the rotor and the vanes;   an inlet port provided in the pump housing and opening to a suction section where a volume of each of the pump chambers gradually increases with rotation of the rotor;   an outlet port provided in the pump housing and opening to a discharge section where the volume of each of the pump chambers gradually decreases with rotation of the rotor;   an inlet passage provided in the pump housing and introducing the working fluid stored in a reservoir tank to the inlet port;   an outlet passage provided in the pump housing and introducing the working fluid discharged from the outlet port to an outside of the pump housing;   a first fluid pressure chamber and a second fluid pressure chamber each provided at an outer peripheral side of the cam ring, the first fluid pressure chamber being located on a side where a volume of the fluid pressure chamber is decreased when the cam ring moves in a direction in which an eccentric amount of the cam ring with respect to the rotor is increased, and the second fluid pressure chamber being located on a side where the volume of the fluid pressure chamber is increased when the cam ring moves in the direction in which the eccentric amount of the cam ring with respect to the rotor is increased;   a first valve accommodation hole formed at the bottom wall portion of the first housing and at some midpoint of the outlet passage;   a first valve body movably provided in the first valve accommodation hole, the first valve body being configured so that movement of the first valve body is controlled by a pressure difference between a suction pressure acting on one end side of the first valve body and a discharge pressure introduced from the outlet passage and acting on the other end side of the first valve body, and the first valve body changes a flow passage cross-sectional area of the outlet passage according to the movement of the first valve body;   a second valve accommodation hole provided in the pump housing;   a high pressure chamber provided at one end side of the second valve accommodation hole and formed so as to communicate with the outlet port;   a control pressure chamber provided at the other end side of the second valve accommodation hole and formed so as to communicate with a downstream side, with respect to the first valve accommodation hole, of the outlet passage; and   a second valve body movably provided in the second valve accommodation hole and controlling a pressure in the first fluid pressure chamber by a pressure difference between a pressure in the high pressure chamber and a pressure in the control pressure chamber.   
     
     
         2 . The variable capacity vane pump as claimed in  claim 1 , wherein:
 the first valve body is provided so as to move along an axial direction of the drive shaft.   
     
     
         3 . The variable capacity vane pump as claimed in  claim 1 , wherein:
 the first valve accommodation hole is provided so that an opening side of the first valve accommodation hole communicates with the discharge section.   
     
     
         4 . The variable capacity vane pump as claimed in  claim 3 , wherein:
 the first valve accommodation hole is provided so as to overlap the discharge section in a circumferential direction of the drive shaft.   
     
     
         5 . The variable capacity vane pump as claimed in  claim 4 , wherein:
 the first valve body is inserted into the first valve accommodation hole from the opening side of the first valve accommodation hole.   
     
     
         6 . The variable capacity vane pump as claimed in  claim 4 , wherein:
 the pump housing has:
 a seal member accommodation space formed into a ring-shape on an outer circumferential side of the drive shaft and accommodating therein a seal member that seals a gap between the pump housing and the drive shaft; 
 a low pressure communication passage connecting the seal member accommodation space and the suction section; and 
 a low pressure introduction passage connecting one end side of the first valve accommodation hole and the seal member accommodation space. 
   
     
     
         7 . The variable capacity vane pump as claimed in  claim 1 , wherein:
 the first valve body is a spool valve that has a land portion and changes the flow passage cross-sectional area of the outlet passage by changing an overlap amount between the land portion and the outlet passage.   
     
     
         8 . The variable capacity vane pump as claimed in  claim 7 , wherein:
 a groove portion is formed at the other end side of the first valve body by cutting in a radial direction of the first valve body.   
     
     
         9 . The variable capacity vane pump as claimed in  claim 7 , further comprising:
 a spring member forcing the first valve body to the other end side of the first valve body, and wherein   the first valve body has, at one end portion thereof, a stopper that limits the movement of the first valve body to the one end side of the first valve body.   
     
     
         10 . The variable capacity vane pump as claimed in  claim 9 , wherein:
 the spring member is a coil spring, and   the first valve body has, at the one end side thereof, a spring retaining portion that accommodates and retains a part of the spring member.   
     
     
         11 . The variable capacity vane pump as claimed in  claim 9 , wherein:
 the first valve body is configured so that when the movement of the first valve body is limited by the stopper, the flow passage cross-sectional area of the outlet passage is a maximum.   
     
     
         12 . The variable capacity vane pump as claimed in  claim 7 , wherein:
 the outlet passage is configured so that rate of change of the flow passage cross-sectional area of the outlet passage is gradually decreased with increase of the discharge pressure acting on the other end side of the first valve body.   
     
     
         13 . The variable capacity vane pump as claimed in  claim 1 , further comprising:
 a spring member provided in the first valve accommodation hole and forcing the first valve body, and wherein   the spring member has a nonlinear spring constant.   
     
     
         14 . The variable capacity vane pump as claimed in  claim 1 , wherein:
 the first valve body directly introduces the working fluid acting on the other end side of the first valve body to the downstream side of the outlet passage.   
     
     
         15 . The variable capacity vane pump as claimed in  claim 1 , wherein:
 the first valve accommodation hole is provided so that a bottom side of the first valve accommodation hole communicates with the inlet passage.   
     
     
         16 . A variable capacity vane pump supplying working fluid to a power steering device of a vehicle, comprising:
 a pump housing formed from a first housing formed into a flat plate and a second housing having a cylindrical portion and a bottom wall portion provided so as to close one end opening of the cylindrical portion, the other end opening of the cylindrical portion being closed by the first housing, the pump housing forming a pump element accommodation space inside the pump housing between the first and second housings;   a drive shaft inserted and rotatably supported in the pump housing;   a drive shaft transmission unit provided at a protruding portion of the drive shaft which protrudes to an outside of the pump housing and transmitting external power to the drive shaft;   a rotor accommodated in the pump element accommodation space and driven and rotated by the drive shaft, the rotor being provided with a plurality of slits in a radial direction of the rotor;   vanes provided in the slits so as to extend and retract;   a ring-shaped cam ring movably provided in the pump element accommodation space and forming a plurality of pump chambers together with the rotor and the vanes;   an inlet port provided in the pump housing and opening to a suction section where a volume of each of the pump chambers gradually increases with rotation of the rotor;   an outlet port provided in the pump housing and opening to a discharge section where the volume of each of the pump chambers gradually decreases with rotation of the rotor;   an inlet passage provided in the pump housing and introducing the working fluid stored in a reservoir tank to the inlet port;   an outlet passage provided in the pump housing and introducing the working fluid discharged from the outlet port to an outside of the pump housing;   a first fluid pressure chamber and a second fluid pressure chamber each provided at an outer peripheral side of the cam ring, the first fluid pressure chamber being located on a side where a volume of the fluid pressure chamber is decreased when the cam ring moves in a direction in which an eccentric amount of the cam ring with respect to the rotor is increased, and the second fluid pressure chamber being located on a side where the volume of the fluid pressure chamber is increased when the cam ring moves in the direction in which the eccentric amount of the cam ring with respect to the rotor is increased;   a first valve accommodation hole formed in a position on a drive shaft transmission unit side of the first housing with respect to the rotor in an axial direction of the drive shaft and at some midpoint of the outlet passage;   a first valve body movably provided in the first valve accommodation hole, the first valve body being configured so that movement of the first valve body is controlled by a pressure difference between a suction pressure acting on one end side of the first valve body and a discharge pressure introduced from the outlet passage and acting on the other end side of the first valve body, and the first valve body changes a flow passage cross-sectional area of the outlet passage according to the movement of the first valve body;   a second valve accommodation hole provided in the pump housing;   a high pressure chamber provided at one end side of the second valve accommodation hole and formed so as to communicate with the outlet port;   a control pressure chamber provided at the other end side of the second valve accommodation hole and formed so as to communicate with a downstream side, with respect to the first valve accommodation hole, of the outlet passage; and   a second valve body movably provided in the second valve accommodation hole and controlling a pressure in the first fluid pressure chamber by a pressure difference between a pressure in the high pressure chamber and a pressure in the control pressure chamber.   
     
     
         17 . The variable capacity vane pump as claimed in  claim 16 , wherein:
 the first valve body is provided so as to move along an axial direction of the drive shaft.   
     
     
         18 . The variable capacity vane pump as claimed in  claim 16 , wherein:
 the first valve accommodation hole is provided so that an opening side of the first valve accommodation hole communicates with the discharge section.   
     
     
         19 . The variable capacity vane pump as claimed in  claim 18 , wherein:
 the first valve accommodation hole is provided so as to overlap the discharge section in a circumferential direction of the drive shaft.   
     
     
         20 . A variable capacity vane pump supplying working fluid to a power steering device of a vehicle, comprising:
 a pump housing formed from a first housing having a cylindrical portion and a bottom wall portion provided so as to close one end opening of the cylindrical portion and a second housing provided so as to close the other end opening of the cylindrical portion, the pump housing forming a pump element accommodation space inside the pump housing between the first and second housings;   a drive shaft inserted and rotatably supported in the pump housing;   a rotor accommodated in the pump element accommodation space and driven and rotated by the drive shaft, the rotor being provided with a plurality of slits in a radial direction of the rotor;   vanes provided in the slits so as to extend and retract;   a ring-shaped cam ring movably provided in the pump element accommodation space and forming a plurality of pump chambers together with the rotor and the vanes;   an inlet port provided in the pump housing and opening to a suction section where a volume of each of the pump chambers gradually increases with rotation of the rotor;   an outlet port provided in the pump housing and opening to a discharge section where the volume of each of the pump chambers gradually decreases with rotation of the rotor;   an inlet passage provided in the pump housing and introducing the working fluid stored in a reservoir tank to the inlet port;   an outlet passage provided in the pump housing and introducing the working fluid discharged from the outlet port to an outside of the pump housing;   a first fluid pressure chamber and a second fluid pressure chamber each provided at an outer peripheral side of the cam ring, the first fluid pressure chamber being located on a side where a volume of the fluid pressure chamber is decreased when the cam ring moves in a direction in which an eccentric amount of the cam ring with respect to the rotor is increased, and the second fluid pressure chamber being located on a side where the volume of the fluid pressure chamber is increased when the cam ring moves in the direction in which the eccentric amount of the cam ring with respect to the rotor is increased;   a first valve accommodation hole formed at the bottom wall portion of the first housing and at some midpoint of the outlet passage;   a first valve body movably provided in the first valve accommodation hole, the first valve body being configured so that movement of the first valve body is controlled by a pressure difference between a suction pressure acting on one end side of the first valve body and a discharge pressure introduced from the outlet passage and acting on the other end side of the first valve body, the first valve body changes a flow passage cross-sectional area of the outlet passage according to the movement of the first valve body, and the working fluid acting on the other end side of the first valve body flows out of the first valve body;   a second valve accommodation hole provided in the pump housing;   a high pressure chamber provided at one end side of the second valve accommodation hole and formed so as to communicate with the outlet port;   a control pressure chamber provided at the other end side of the second valve accommodation hole and formed so as to communicate with a downstream side, with respect to the first valve accommodation hole, of the outlet passage; and   a second valve body movably provided in the second valve accommodation hole and controlling a pressure in the first fluid pressure chamber by a pressure difference between a pressure in the high pressure chamber and a pressure in the control pressure chamber.