US 7,455,507 B2
Structure for preventing cavitation erosion of oil pump
Miyuki Takahashi, Kanagawa-ken (Japan); Hidenori Egashira, Kanagawa-ken (Japan); and Ryou Abe, Kanagawa-ken (Japan)
Assigned to Misubishi Heavy Industries, Ltd., Tokyo (Japan)
Filed on Mar. 23, 2007, as Appl. No. 11/727,105.
Claims priority of application No. 2006-092124 (JP), filed on Mar. 29, 2006.
Prior Publication US 2007/0231179 A1, Oct. 04, 2007
Int. Cl. F03C 2/00 (2006.01); F04C 2/00 (2006.01)
U.S. Cl. 418—132  [418/131; 418/206.1; 418/206.6; 418/206.7] 3 Claims
OG exemplary drawing
 
1. A structure for preventing cavitation erosion of an oil pump, comprising:
pump gears engaging each other and driven by a pump drive gear, the pump gears being accommodated in a pump case such that small side gaps are defined between both side faces of the pump gears and a side wall face of a gear room of the pump case and a pump gear side end face of a pump cover and such that oil is discharged from the pump by rotation of the engaged pump gears,
wherein a side face of the pump gear is formed into a stepped face such that an annular region extending radially from a diameter of a shoulder at the stepped face, the diameter of the shoulder at the stepped face being smaller than a dedendum circle diameter of the pump gear and larger than an outer diameter of a pump gear bearing, to an addendum circle diameter of the pump gear is recessed by a certain depth to increase a size of a side gap in the recessed annular region so that the size of the side gap in the recessed annular region is larger than a size of a side gap in a region between the diameter of the shoulder at the stepped face to the outer diameter of the pump gear bearing.