Fluid Pump: Description and Operation

4. OIL PUMP





Construction
The vane pump is housed in the oil pump housing. It consists of a rotor, vanes, vane rings, cam ring, control piston, return spring, seal ring and oil pump cover.
Hydraulic pressure (feedback pressure) from the oil passage of the pressure regulator valve is applied to the back of the control piston.





Function
1. The Automatic Transmission Fluid (ATF) is drawn through the oil strainer mounted under the control valve ASSY, and is routed to the transmission case, to the oil pump housing, and to the oil pump cover. It then goes to the suction port of section A shown in the Figure.
2. The ATF sucked into section A rotates in the direction of the arrow (driven directly by engine), and is compressed at the delivery side of section B. It is then discharged.
3. The discharged ATF flows from the oil pump cover to the oil pump housing. It then goes to the transmission case, the control valve and to the regulator valve, thus serving as hydraulic oil and lubricating oil for the torque converter clutch, valves, clutch and brake.
4. As engine speed increases, the delivery rate of the vane pump also increases.
5. Feedback pressure from the regulator valve is applied to section C in the Figure. The cam ring position (the amount of eccentricity) is controlled by this pressure so that the pump delivery rate remains constant at speeds exceeding the preset pump speed.
6. As the cam ring position changes, the suction volume at section A varies. In this manner, the pump delivery volume is controlled.