Oil pump

Abstract

An oil pump includes: a pump housing having a rotor accommodation space in an inner portion of the pump housing; a rotor accommodated in the rotor accommodation space; a shaft portion disposed inside the rotor; and a passage which is provided to straddle at least one of the pump housing and the rotor and the shaft portion and which communicates a pump chamber which is formed by the rotor inside the pump housing with an outside of the pump housing.

What is claimed is: 
     
         1 . An oil pump comprising:
 a pump housing having a rotor accommodation space in an inner portion of the pump housing;   a rotor accommodated in the rotor accommodation space;   a shaft portion disposed inside the rotor; and   a passage which is provided to straddle at least one of the pump housing and the rotor and the shaft portion and which communicates a pump chamber which is formed by the rotor inside the pump housing with an outside of the pump housing.   
     
     
         2 . The oil pump according to  claim 1 ,
 wherein the passage includes a first passage portion which is provided to straddle at least one of the pump housing and the rotor and the shaft portion and extends in a direction intersecting an axial direction of the shaft portion, and a second passage portion which is provided in the shaft portion and extends in the axial direction.   
     
     
         3 . The oil pump according to  claim 1 ,
 wherein the shaft portion includes an opening/closing mechanism which opens and closes the passage.   
     
     
         4 . The oil pump according to  claim 2 ,
 wherein the shaft portion includes a rotary shaft which rotationally drives the rotor,   the rotary shaft includes an opening/closing mechanism which opens and closes the passage,   the opening/closing mechanism includes an opening/closing valve which includes a sealing wall and a communication bore which is disposed at a position deviated in the axial direction of the rotary shaft with respect to the sealing wall and is capable of moving in the axial direction of the rotary shaft, and   the opening/closing mechanism is configured to close the passage by moving to one side of the axial direction of the rotary shaft to dispose the sealing wall between the first passage portion and the second passage portion and to open the passage by moving to the other side of the axial direction of the rotary shaft to dispose, instead of the sealing wall, the communication bore between the first passage portion and the second passage portion.   
     
     
         5 . The oil pump according to  claim 4 ,
 wherein the opening/closing mechanism is configured to move the opening/closing valve according to an internal pressure of a discharging port and is configured to close the passage by disposing the sealing wall between the first passage portion and the second passage portion in a case in which the internal pressure of the discharging port is low and to open the passage by disposing, instead of the sealing wall, the communication bore between the first passage portion and the second passage portion in a case in which the internal pressure of the discharging port is high.   
     
     
         6 . The oil pump according to  claim 5 ,
 wherein the opening/closing mechanism includes
 a pressure chamber which is provided on one side in the axial direction of the rotary shaft of the opening/closing valve, communicates with the discharging port via a pressure passage, and pressurizes the opening/closing valve to move the opening/closing valve, 
 a biasing member which is provided on the other side in the axial direction of the rotary shaft of the opening/closing valve and biases the opening/closing valve toward the pressure chamber, and 
 a restriction portion which restricts movement of the opening/closing valve to the pressure chamber side, and 
   the opening/closing mechanism is configured
 to close the passage by disposing the sealing wall between the first passage portion and the second passage portion in a state in which the opening/closing valve and the restriction portion are caused to abut against each other by a biasing force of the biasing member in a case in which the internal pressure of the discharging port and the pressure chamber is low and 
 to open the passage by disposing, instead of the sealing wall, the communication bore between the first passage portion and the second passage portion in a state in which the opening/closing valve and the restriction portion are separated from each other against the biasing force of the biasing member by the internal pressure of the pressure chamber via the opening/closing valve in a case in which the internal pressure of the discharging port and the pressure chamber is high. 
   
     
     
         7 . The oil pump according to  claim 1 ,
 wherein the rotor is an inscribed gear rotor which includes an outer rotor including a plurality of internal teeth and an inner rotor including a plurality of external teeth which mesh with the internal teeth of the outer rotor, or the rotor is a vane rotor which includes a rotor main body and a plurality of vanes which are provided to protrude outward from the rotor main body and form the pump chamber.   
     
     
         8 . The oil pump according to  claim 1 ,
 wherein the shaft portion includes
 a rotary shaft which includes a recessed portion having a circular cross-section that is orthogonal to an axial direction of the shaft portion and extending in the axial direction and which rotates together with the rotor, and 
 a fixed shaft which includes a first member which is fixed to the pump housing and a second member which is inserted into the recessed portion and is connected to the first member in a state of being capable of moving in a direction orthogonal to the axial direction. 
   
     
     
         9 . The oil pump according to  claim 8 ,
 wherein the fixed shaft includes a turn-stopping portion which connects the first member and the second member to each other in a state in which the second member is capable of moving in the direction orthogonal to the axial direction relative to the first member.   
     
     
         10 . The oil pump according to  claim 7 ,
 wherein the passage includes a first passage portion which is provided to straddle at least one of the pump housing and the inner rotor and the shaft portion and extending in a direction intersecting an axial direction of the shaft portion, and a second passage portion which is provided in the shaft portion and extends in the axial direction,   the shaft portion includes
 a rotary shaft which includes a recessed portion having a circular cross-section that is orthogonal to the axial direction of the shaft portion and extends in the axial direction and which rotates together with the inner rotor, and 
 a fixed shaft which includes a first member which is fixed to the pump housing and a second member which is inserted into the recessed portion and is connected to the first member in a state of being capable of moving in a direction orthogonal to the axial direction, and 
   the first passage portion includes an outer passage portion which is provided to straddle the rotary shaft and the inner rotor and an inner passage portion which is provided in the fixed shaft and communicates with the outer passage portion at a predetermined rotational position of the rotary shaft.   
     
     
         11 . The oil pump according to  claim 7 ,
 wherein a tooth bottom of the inner rotor is provided with a bubble introduction portion which is disposed between the pump chamber and the passage, collects the bubbles inside the pump chamber and introduces the collected bubbles into the passage.   
     
     
         12 . The oil pump according to  claim 7 ,
 wherein the passage includes a first passage portion which is provided to straddle at least one of the pump housing and the inner rotor and the shaft portion and extends in a direction intersecting the axial direction of the shaft portion, and a second passage portion which is provided in the shaft portion and extends in the axial direction, and   one end of the first passage portion is connected to a tooth bottom of the inner rotor.   
     
     
         13 . The oil pump according to  claim 2 ,
 wherein the passage is provided to straddle the pump housing and the shaft portion and the passage on the pump housing side is formed in a groove shape which communicates the pump chamber and the passage on the shaft portion side with each other.