OIL PUMP AND AUTOMATIC SPEED CHANGER WITH THE SAME

摘要

An oil pump where, even if a pump cover is formed of a light alloy without changing the material, occurrence of cavitation erosion is appropriately suppressed in high-speed rotation of a drive gear. Either a pump body (10) or a pump cover (15) is formed of cast iron and the other, of a light alloy, and the length of either a notch (26a) or a notch (26b) formed in the pump body (10) or pump cover (15) that is formed of the light alloy is set greater than the length of the notch formed in the pump body (10) or pump cover (15) that is formed of the cast iron. This enables bubbles produced in hydraulic oil in an operation chamber (R) in high-speed rotation of a drive gear (30) to be crushed by high-pressure hydraulic oil flowing back toward the operation chamber (R) through the longer notch, the crush occurring on the inner surface side, facing the operation chamber (R), of the pump body (10) or pump cover (15) that is formed of the cast iron.