Oil pump

Abstract

An oil pump includes: an outer rotor including internal teeth; an inner rotor including external teeth meshing with the internal teeth; a drive shaft connected to the inner rotor and configured to rotationally drive the inner rotor; and a housing including a pump chamber accommodating the inner and outer rotors. In the housing, a suction port and a discharge port are formed. The discharge port includes a first discharge port and a second discharge port. The suction port includes first and second suction ports respectively disposed on the same side as the first and second discharge ports. A pressure reducing oil passage communicating with the second discharge port and configured to reduce pressure of oil in the second discharge port is formed on the side of the second discharge port.

What is claimed is: 
     
         1 . An oil pump comprising:
 an outer rotor including internal teeth;   an inner rotor including external teeth meshing with the internal teeth;   a drive shaft connected to the inner rotor and configured to rotationally drive the inner rotor; and   a housing including a pump chamber accommodating the inner rotor and the outer rotor, wherein   in the housing, a suction port through which oil is suctioned into the pump chamber and a discharge port through which the oil in the pump chamber is discharged are formed,   the discharge port includes a first discharge port directly connected to a discharge oil passage and a second discharge port with the pump chamber sandwiched therebetween,   the suction port includes a first suction port disposed on the same side as the first discharge port and a second suction port disposed on the same side as the second discharge port with the pump chamber sandwiched therebetween, and   a pressure reducing oil passage communicating with the second discharge port and configured to reduce pressure of the oil in the second discharge port is formed on the side of the second discharge port of the discharge port.   
     
     
         2 . The oil pump according to  claim 1 , wherein
 the pressure reducing oil passage is formed from the second discharge port to an outside.   
     
     
         3 . The oil pump according to  claim 1 , wherein
 the pressure reducing oil passage is formed from the second discharge port to the second suction port.   
     
     
         4 . The oil pump according to  claim 3 , wherein
 the pressure reducing oil passage is formed outside the second discharge port and the second suction port with respect to the drive shaft, and an angle formed by two virtual straight lines on the side where the pressure reducing oil passage is formed when an axial center of the drive shaft is connected to both ends of the pressure reducing oil passage by the virtual straight lines is 180 degrees or more.   
     
     
         5 . The oil pump according to according to  claim 1 , wherein
 the second discharge port is formed in a crescent shape along a portion where the internal teeth of the outer rotor and the external teeth of the inner rotor mesh with each other as viewed in a direction along the drive shaft, and one end side of both ends in a longitudinal direction is formed to be wider than the other end side, and   the pressure reducing oil passage is formed so as to communicate with the other end side of the second discharge port.   
     
     
         6 . The oil pump according to  claim 1 , wherein
 the pressure reducing oil passage is formed of a groove formed in the housing.