Oil pump

Abstract

An oil pump includes: an inner rotor including external teeth; an outer rotor including internal teeth; a housing configured to accommodate the inner and outer rotors; an inlet port formed in the housing and configured to guide oil into a pump chamber between the external and internal teeth; an outlet port formed in the housing and configured to guide the oil to the outside of the pump chamber; and a discharge hole formed in the housing and configured to guide bubbles in the oil to the outside of the pump chamber. The discharge hole communicates with the pump chamber earlier than a timing when the pump chamber and the outlet port communicate with each other. The outlet port communicates with the pump chamber later than a timing when the pump chamber has a maximum volume.

What is claimed is: 
     
         1 . An oil pump comprising:
 an inner rotor including external teeth;   an outer rotor including internal teeth that engage with the external teeth of the inner rotor;   a housing configured to accommodate the inner rotor and the outer rotor;   an inlet port formed in the housing and configured to guide oil into a pump chamber between the external teeth and the internal teeth;   an outlet port formed in the housing and configured to guide the oil to the outside of the pump chamber; and   a discharge hole formed in the housing and configured to guide bubbles contained in the oil to the outside of the pump chamber,   wherein the discharge hole is provided to communicate with the pump chamber earlier than a timing when the pump chamber and the outlet port communicate with each other, and   the outlet port is provided to communicate with the pump chamber later than a timing when the pump chamber has a maximum volume.   
     
     
         2 . The oil pump according to  claim 1 ,
 wherein the discharge hole is formed to be opened at a position between an opening of the inlet port and an opening of the outlet port, and closer to the opening of the outlet port than the opening of the inlet port.   
     
     
         3 . The oil pump according to  claim 1 ,
 wherein the inlet port is provided to be closed earlier than the timing when the pump chamber has the maximum volume.   
     
     
         4 . The oil pump according to  claim 1 ,
 wherein the discharge hole is formed to be opened at a position closer to a rotating shaft of the inner rotor than the opening of the outlet port in a radial direction of the inner rotor.   
     
     
         5 . The oil pump according to  claim 1 ,
 wherein the inner rotor has groove portions provided in tooth bottom portions of the external teeth.   
     
     
         6 . The oil pump according to  claim 5 ,
 wherein a groove portion of the inner rotor is formed in an arc shape when viewed in a direction of the rotating shaft of the inner rotor.   
     
     
         7 . The oil pump according to  claim 5 ,
 wherein the groove portion of the inner rotor is formed such that both ends of the groove portion in a rotation direction of the inner rotor are connected to the pump chamber.   
     
     
         8 . The oil pump according to  claim 5 ,
 wherein the discharge hole is opened at a position, in a radial direction of the inner rotor, which overlaps with the groove portion but does not overlap with the pump chamber.   
     
     
         9 . The oil pump according to  claim 3 ,
 wherein the inlet port is provided to be closed earlier than the timing when the pump chamber has the maximum volume so that the pressure in the pump chamber becomes a pressure that generates bubbles.