Patent ID: 7165955

Claim:
A trochoid type oil pump comprising: a rotor chamber comprising an intake port and a discharge port; outer and inner rotors; and shallow grooves formed on a side of an initial end portion of said discharge port on a circular circumference of a track of positions of bottom portions of teeth created by the rotation of said outer rotor, wherein, in a state in which sealed spaces formed by said outer rotor, said inner rotor and a partition part between a final end portion of said intake port and the initial end portion of said discharge port are decreased from a maximum value, said sealed spaces communicate with one of said shallow grooves in which the position of discharge initiation is separated from the position of the bottom portions of the teeth of the inner rotor and whose groove width is positioned on the circular circumference of the track of the positions of the bottom portions of the teeth of the outer rotor are established, and said sealed spaces are caused to continuously communicate with said shallow grooves in the direction of the circular circumference of the track.