Patent ID: 8920148

Claim:
An oil pump comprising: an inner rotor that has a plurality of external teeth; an outer rotor that is eccentrically provided and has a plurality of internal teeth that mesh with the external teeth of the inner rotor; and an oil pump body that accommodates the outer rotor and the inner rotor, wherein by rotationally driving the inner rotor to increase and decrease a space part between the internal teeth and the external teeth, an intake stroke that suctions hydraulic oil from an intake port formed in the oil pump body and a discharge stroke that discharges the suctioned hydraulic oil to a discharge port formed in the oil pump body are performed, the intake port communicates with the space part at an interval where the volume of the space part increased, and of which a finish end portion is formed so as to keep communication between the intake port and the space part at the time of the maximum volume of the space part, and between the intake stroke and the discharge stroke, a confinement stroke that cuts off the suctioned hydraulic oil from the intake port and confines the suctioned hydraulic oil in the space part and a compression stroke that reduces the space part and compresses the confined hydraulic oil are performed, and hydraulic oil is prevented from flowing out from the space formed by the internal teeth and the external teeth while the compression stroke is performed due to maintaining a pressure in the space part below a pressure in the discharge port during the compression stroke, and an interval is set between an end portion in a rotation direction side of the inner rotor in the intake port and an end portion in the rotation direction reverse side of the inner rotor in the discharge port such that a rotation angle of the inner rotor during the compression stroke is 21 to 27 degrees.