Hydraulic Oil Pump for Transmission

Automatic Transmission Oil Pump

The automatic transmission oil pump, also known as the Gear Pump, plays a very important role in the automatic transmission and is one of the most important assemblies of the automatic transmission.

The oil pump is installed at the rear of the hydraulic torque converter and driven by the shaft sleeve at the rear of the hydraulic torque converter. In the oil supply system of automatic transmission, the commonly used oil pumps include internal gear oil pump, rotor oil pump, and vane oil pump.

The structure of the automatic transmission oil pump consists of an oil seal, an oil pump front end cover, an O-ring seal, a pinion, an internal gear, an oil pump rear end cover, and a seal ring.

Critical parameters:

Gerotor pump

As shown in Figure 3, a rotor pump consists of an inner and outer rotor, with the inner rotor having one tooth less than the outer rotor. There is no crescent shaped partition plate in the rotor pump. The shape of the convex surface of the rotor teeth keeps the teeth in tangential contact, and each inner tooth of the rotor pump continuously slides into contact with the outer tooth surface, which ensures the sealing of the working cavity between the inner and outer teeth (oil suction cavity and oil discharge cavity) and prevents the leakage of pressure oil.

The sliding speed between the inner and outer tooth contact surfaces of the rotor pump is relatively low, thereby reducing the wear of the contact surfaces. The shaft rotates 6-13 revolutions (depending on the number of teeth) and the contact point completes a cycle. The opening and closing of the interdental cavity is gradually accomplished through long oil suction and discharge ports, which minimizes oil pressure shocks and flow fluctuations.