Pump apparatus

Abstract

A pump apparatus includes: a spool valve including a first land portion, a second land portion, and a third land portion; a first pressure chamber into which an upstream pressure of the metering orifice is introduce; a second pressure chamber into which a downstream pressure of the metering orifice is introduced; a third pressure chamber into which the pressure of the discharge passage is introduced; a fourth pressure chamber into which a low pressure is introduced; and a first fluid pressure chamber side communication passage which is formed in the pump housing which is arranged to selectively supply the pressure of the third pressure chamber and the pressure of the fourth pressure chamber to the first fluid pressure chamber in accordance with the movement of the spool valve.

What is claimed is: 
     
         1 . A pump apparatus comprising:
 a pump housing including a pump element receiving portion which is formed within the pump housing;   a drive shaft which is inserted within the pump element receiving portion, and which is rotatably supported by the pump housing;   a rotor which is provided within the pump element receiving portion, which is driven by the drive shaft to rotate, and which includes a plurality of slots in a circumferential direction;   a plurality of vanes which are provided in the slots of the rotor to be moved in a radially outward direction and in a radially inward direction;   a cam ring which is arranged to be moved within the pump element receiving portion, which has an annular shape, and which forms a plurality of pump chambers radially inside the cam ring, with the rotor and the vanes;   a suction opening which is formed in the pump housing, and which is opened in a suction region in which volumes of the plurality of the pump chambers are increased in accordance with the rotation of the rotor;   a discharge opening which is formed in the pump housing, and which is opened in a discharge region in which the volumes of the pump chambers are decreased in accordance with the rotation of the rotor;   a discharge passage connected with the discharge opening;   a metering orifice which is formed in the middle of the discharge passage;   a first fluid pressure chamber which is formed between the pump element receiving portion and the cam ring, and which is formed on a side on which a volume of the first fluid pressure chamber is decreased when the cam ring is moved on the side on which the eccentric amount of the cam ring with respect to the drive shaft is increased;   a second fluid pressure chamber which is formed between the pump element receiving portion and the cam ring, and which is formed on a side on which a volume of the second fluid pressure chamber is decreased when the cam ring is moved on the side on which the eccentric amount of the cam ring with respect to the drive shaft is increased;   a control valve receiving hole which is formed in the pump housing;   a spool valve which is arranged to be moved within the control valve receiving hole, the spool valve including;
 a first land portion which is provided on a first end side of the spool valve in a movement direction of the spool valve, 
 a second land portion which is provided on second end side of the spool valve in the movement direction of the spool valve, and 
 a third land portion which is provided between the first land portion and the second land portion in the movement direction of the spool valve; 
   a first pressure chamber which is formed within the control valve receiving hole, which is provided on the first end side of the first land portion in the movement direction of the spool valve, and into which an upstream pressure of the metering orifice is introduced;   a second pressure chamber which is formed within the control valve receiving hole, which is formed on second end side of the second land portion in the movement direction of the spool valve, and into which a downstream pressure of the metering orifice is introduced;   a third pressure chamber which is formed within the control valve receiving hole, which is provided between the first land portion and the third land portion in the movement direction of the spool valve, and into which the pressure of the discharge passage is introduced;   a fourth pressure chamber which is formed within the control valve receiving hole, which is provided between the second land portion and the third land portion in the movement direction of the spool valve, and into which a low pressure is introduced; and   a first fluid pressure chamber side communication passage which is formed in the pump housing, which includes a first end portion which is connected to the valve receiving hole, and a second end portion which is connected to the first fluid pressure chamber, and which is arranged to selectively supply the pressure of the third pressure chamber and the pressure of the fourth pressure chamber to the first fluid pressure chamber in accordance with the movement of the spool valve.   
     
     
         2 . The pump apparatus as claimed in  claim 1 , wherein the pump apparatus further comprises a fourth land portion which is provided between the second land portion and the third land portion in the movement direction of the spool valve, a fifth pressure chamber which is formed within the control valve receiving hole, which is formed between the second land portion and the fourth land portion in the movement direction of the spool valve, and into which the pressure of the discharge passage is introduced, and a second fluid pressure chamber side communication passage which is formed in the pump housing, which includes a first end portion connected to the valve receiving hole, and a second end portion connected to the second fluid pressure chamber, and which is arranged to selectively supply the pressure of the fifth pressure chamber and the pressure of the fourth pressure chamber to the second fluid pressure chamber in accordance with the movement of the spool valve; and the fourth pressure chamber is formed between the third land portion and the fourth land portion in the movement direction of the spool valve. 
     
     
         3 . The pump apparatus as claimed in  claim 1 , wherein the spool valve is formed so that clearances between an outer circumference surface of the first land portion and an outer circumference surface of the second land portion, and an inner circumference surface of the control valve receiving hole are smaller than clearances between an outer circumference surface of the third land portion and an outer circumference surface of the fourth land portion, and the inner circumference surface of the control valve receiving hole. 
     
     
         4 . The pump apparatus as claimed in  claim 3 , wherein the pump apparatus is connected through the discharge passage to a continuously variable transmission to supply the hydraulic fluid to the continuously variable transmission. 
     
     
         5 . The pump apparatus as claimed in  claim 2 , wherein the third pressure chamber and the fifth pressure chamber receive the pressure of the discharge passage on the same side of the upstream side or the downstream side of the metering orifice. 
     
     
         6 . The pump apparatus as claimed in  claim 5 , wherein the third pressure chamber and the fifth pressure chamber receive the pressure of the discharge passage on the upstream side of the metering orifice. 
     
     
         7 . The pump apparatus as claimed in  claim 5 , wherein the third pressure chamber and the fifth pressure chamber receive the pressure of the discharge passage on the downstream side of the metering orifice. 
     
     
         8 . The pump apparatus as claimed in  claim 2 , wherein the third pressure chamber receives the pressure of the discharge passage on an upstream side of the metering orifice; and the fifth pressure chamber receives the pressure of the discharge passage on a downstream side of the metering orifice. 
     
     
         9 . The pump apparatus as claimed in  claim 3 , wherein the pump apparatus further comprises a first cam passage throttling portion which is provided in a first cam control pressure introduction passage connecting the third pressure chamber and the discharge passage, and a second cam passage throttling portion provided in a second cam control pressure introduction passage connecting the fifth pressure chamber and the discharge passage. 
     
     
         10 . The pump apparatus as claimed in  claim 2 , wherein the pump apparatus further comprises a first spool passage throttling portion which is provided in a first spool control pressure introduction passage connecting the first pressure chamber and the discharge passage on an upstream side of the metering orifice, and a second spool passage throttling portion which is provided in a second spool control pressure introduction passage connecting the second pressure chamber and the discharge passage on a downstream side of the metering orifice. 
     
     
         11 . The pump apparatus as claimed in  claim 2 , wherein the pump apparatus further includes a first spool control pressure introduction passage connecting the first pressure chamber and the discharge passage on an upstream side of the metering orifice, a first cam control pressure introduction passage connecting the third pressure chamber and the discharge passage, a second cam control pressure introduction passage connecting the fifth pressure chamber and the discharge passage, and a second spool control pressure introduction passage connecting the second pressure chamber and the discharge passage on a downstream side of the metering orifice; and the first spool control pressure introduction passage and the first cam control pressure introduction passage, or the second cam control pressure introduction passage and the second spool control pressure introduction passage have throttling portions. 
     
     
         12 . The pump apparatus as claimed in  claim 2 , wherein the pump apparatus further includes a first spool control pressure introduction passage connecting the first pressure chamber and the discharge passage on an upstream side of the metering orifice, a first cam control pressure introduction passage connecting the third pressure chamber and the discharge passage, a second cam control pressure introduction passage connecting the fifth pressure chamber and the discharge passage, and a second spool control pressure introduction passage connecting the second pressure chamber and the discharge passage on a downstream side of the metering orifice; and each of the first spool control pressure introduction passage, the first cam control pressure introduction passage, the second cam control pressure introduction passage, and the second spool control pressure introduction passage has a throttling portion. 
     
     
         13 . The pump apparatus as claimed in  claim 1 , wherein the second fluid pressure chamber receives a suction pressure. 
     
     
         14 . The pump apparatus as claimed in  claim 1 , wherein the pump apparatus further comprises a solenoid which is controlled to be driven in accordance with a driving state of a vehicle, and which is arranged to push the first end side of the spool valve through a rod provided to extend within the first pressure chamber, and thereby to perform a position control of the spool valve. 
     
     
         15 . A pump apparatus comprising:
 a pump housing including a pump element receiving portion which is formed within the pump housing;   a drive shaft which is inserted within the pump element receiving portion, and which is rotatably supported by the pump housing;   a rotor which is provided within the pump element receiving portion, which is driven by the drive shaft to rotate, and which includes a plurality of slots in a circumferential direction;   a plurality of vanes which are provided in the slots of the rotor to be moved in a radially outward direction and in a radially inward direction;   a cam ring which is provided within the pump element receiving portion, which has an annular shape, and which forms a plurality of pump chambers radially inside the cam ring, with the rotor and the vanes;   a suction opening which is formed in the pump housing, and which is opened in a suction region in which volumes of the plurality of the pump chambers are increased in accordance with the rotation of the rotor;   a discharge opening which is formed in the pump housing, and which is opened in a discharge region in which the volumes of the pump chambers are decreased in accordance with the rotation of the rotor;   a discharge passage connected with the discharge opening;   a metering orifice which is formed in the middle of the discharge passage;   a control valve receiving hole which is formed in the pump housing;   a spool valve which is arranged to be moved within the control valve receiving hole, the spool valve including;
 a first land portion which is provided on a first end side of the spool valve in a movement direction of the spool valve, 
 a second land portion which is provided on second end side of the spool valve in the movement direction of the spool valve, and 
 a third land portion which is provided between the first land portion and the second land portion in the movement direction of the spool valve; 
   a first pressure chamber which is formed within the control valve receiving hole, which is provided on the first end side of the first land portion in the movement direction of the spool valve, and into which an upstream pressure of the metering orifice is introduced;   a second pressure chamber which is formed within the control valve receiving hole, which is formed on second end side of the second land portion in the movement direction of the spool valve, and into which a downstream pressure of the metering orifice is introduced;   a third pressure chamber which is formed within the control valve receiving hole, which is provided between the first land portion and the third land portion in the movement direction of the spool valve, and into which the pressure of the discharge passage is introduced;   a fourth pressure chamber which is formed within the control valve receiving hole, which is provided between the second land portion and the third land portion in the movement direction of the spool valve, and into which a low pressure is introduced; and   an outlet passage which is provided in the pump housing, which includes a first end portion connected to the valve receiving hole, and a second end portion connected to the suction opening, and which is arranged to discharge the hydraulic fluid within the third pressure chamber to the suction opening's side in accordance with the movement of the spool valve.   
     
     
         16 . The pump apparatus as claimed in  claim 15 , wherein the pump apparatus further comprises a solenoid which is controlled to be driven in accordance with a driving state of a vehicle, and which is arranged to push the first end side of the spool valve through a rod provided to extend within the first pressure chamber, and thereby to perform a position control of the spool valve.