Oil pump

Abstract

An oil pump includes: an inner rotor having external teeth; an outer rotor having internal teeth engaging with the external teeth; a housing that houses the inner and outer rotors; a suction port formed in the housing and guiding oil into a pump chamber; a discharge port formed in the housing and guiding the oil to outside the pump chamber; and a discharge passage through which the pump chamber and an outside area communicate with each other and that discharges a bubble in the oil inside the pump chamber to the outside area. A bubble accommodation portion having a recess shape is formed in a side surface portion of each of the external teeth on a side opposite to a rotation direction of the inner rotor.

What is claimed is: 
     
         1 . An oil pump comprising:
 an inner rotor having a plurality of external teeth;   an outer rotor having a plurality of internal teeth that engage with the plurality of external teeth of the inner rotor;   a housing that houses the inner rotor and the outer rotor;   a suction port that is formed in the housing and guides oil into a pump chamber formed by the plurality of external teeth and the plurality of internal teeth;   a discharge port that is formed in the housing and guides the oil to outside the pump chamber; and   a discharge passage through which the pump chamber and an outside area of the housing communicate with each other and that discharges a bubble contained in the oil inside the pump chamber to the outside area of the housing, wherein   a bubble accommodation portion having a recess shape recessed to a side in a rotation direction of the inner rotor is formed in a side surface portion of each of the plurality of external teeth on a side in an opposite direction of the rotation direction of the inner rotor.   
     
     
         2 . The oil pump according to  claim 1 , wherein
 the discharge passage includes a discharge hole disposed in a tooth bottom portion between the external teeth of the inner rotor or in a portion of the housing which corresponds to the tooth bottom portion, and   the bubble accommodation portion is disposed to extend to a position at which the bubble accommodation portion communicates with the discharge hole in a radial direction of the inner rotor.   
     
     
         3 . The oil pump according to  claim 2 , wherein
 in an extending direction of a rotation axis of the inner rotor, a depth of the bubble accommodation portion on a discharge hole side is shallower than a depth of the bubble accommodation portion on a side opposite to the discharge hole.   
     
     
         4 . The oil pump according to  claim 2 , wherein
 the discharge hole is disposed in a portion of the housing which corresponds to the tooth bottom portion,   when viewed in the rotation direction of the inner rotor, the bubble accommodation portion is configured to close a portion of the side surface portion of the external teeth on a side opposite to the discharge hole, and open a portion of the side surface portion of the external teeth on a discharge hole side, and   the bubble accommodation portion and the discharge hole communicate with each other in an extending direction of a rotation axis of the inner rotor.   
     
     
         5 . The oil pump according to  claim 4 , wherein
 in the radial direction of the inner rotor, an end portion of the bubble accommodation portion on the discharge hole side is flush with an end portion of the discharge hole on the rotation axis side, or is located closer to the rotation axis side than the end portion of the discharge hole on the rotation axis side.   
     
     
         6 . The oil pump according to  claim 1 , wherein
 the bubble accommodation portion is disposed at a position of the side surface portion of each of the external teeth of the inner rotor, which is capable of accommodating the bubble flowing due to a flow of the oil leaking and flowing in the rotation direction from an inter-tooth space between the internal teeth of the outer rotor and the external teeth of the inner rotor.