Abstract: An oil pump has a pump body, an outer rotor, and an inner rotor. The pump body includes a rotor chamber, an inlet port and an outlet port formed in the rotor chamber, an inlet passage communicating with the inlet port, an outlet passage communicating with the outlet port, a relief valve, a relief chamber formed on a discharge side of the relief valve, and an oil return passage formed from the relief chamber to the inlet passage. The outer rotor is supported by the inner circumferential support wall of the rotor chamber. The oil return passage is formed in the inner circumferential support wall as a groove-like recess and opens along an outer circumferential surface of the outer rotor.

Abstract: An oil pump has a pump body, an outer rotor, and an inner rotor. The pump body includes a rotor chamber, an inlet port and an outlet port formed in the rotor chamber, an inlet passage communicating with the inlet port, an outlet passage communicating with the outlet port, a relief valve, a relief chamber formed on a discharge side of the relief valve, and an oil return passage formed from the relief chamber to the inlet passage. The outer rotor is supported by the inner circumferential support wall of the rotor chamber. The oil return passage is formed in the inner circumferential support wall as a groove-like recess and opens along an outer circumferential surface of the outer rotor.

Abstract: The present invention provides an oil pump in which eroding of the inside of the pump due to cavitation and erosion is prevented by minimizing the pressure change in a fluid when inter-tooth spaces formed by an inner rotor and an outer rotor transport the fluid from the intake port to the discharge port. The oil pump comprises: an inner rotor; an outer rotor; an intake port; a discharge port; a transfer side partition part formed between a terminal end of the intake port and a leading end of the discharge port; and a shallow groove which is formed in the transfer side partition part, and which communicates with the discharge port but does not communicate with the intake port. The shallow groove does not intersect with the cell on the transfer side partition part, and is positioned farther inward than the circular locus of the gear bottom parts of the inner rotor.

Abstract: The present invention provides an oil pump in which eroding of the inside of the pump due to cavitation and erosion is prevented by minimizing the pressure change in a fluid when inter-tooth spaces formed by an inner rotor and an outer rotor transport the fluid from the intake port to the discharge port. The oil pump comprises: an inner rotor; an outer rotor; an intake port; a discharge port; a transfer side partition part formed between a terminal end of the intake port and a leading end of the discharge port; and a shallow groove which is formed in the transfer side partition part, and which communicates with the discharge port but does not communicate with the intake port. The shallow groove does not intersect with the cell on the transfer side partition part, and is positioned farther inward than the circular locus of the gear bottom parts of the inner rotor.