Oil Pump: Description and Operation

Volume Rate Controlled Oil Pump

Low delivery rate







One measure to reduce the required drive power of the oil pump is the use of a flow rate control. As a result, a vane pump whose delivery characteristics can be changed using a rotatable adjusting ring is installed in the engine of the Cayenne S Hybrid. This adjusting ring can be loaded with oil pressure via the control surfaces 1 + 5 and pivoted against the force of the control spring. In the lower rpm range, the engine control unit connects the energized control valve to ground and opens the oil duct to the second control surface of the adjusting ring. Both oil flows then act on both control surfaces with the same pressure. The resultant forces are greater than the force of the control spring and pivot the adjusting ring in an counter-clockwise direction. The adjusting ring swivels into the center of the vane pump and reduces the delivery space between the pump cells. The lower pressure level is switched depending on the engine load, engine speed, oil temperature and other operating parameters, thereby reducing the drive power of the oil pump.







High delivery rate







As from an engine speed of 2,500 rpm or a torque of 300 Nm (full-throttle acceleration), the engine control unit isolates the solenoid valve from the ground connection so that the oil duct to control surface 2 is closed. The oil pressure present then acts only on control surface 1 and opposes the force of the control spring with a lower force. The control spring then pivots the adjusting ring around the support in a clockwise direction. The adjusting ring now swivels out of the centre position and increases the delivery space between the individual cells. A greater quantity of oil is delivered due to the larger spaces between the cells. The higher oil flow quantity is opposed by resistance from the oil bores and the bearing clearance of the crankshaft, which allows the oil pressure to increase. Realisation of a volume flow-controlled oil pump with two pressure stages was therefore possible.