Volume Rate Controlled Oil Pump

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.

Oil pressure monitoring

Two oil pressure switches are responsible for monitoring the oil pressure. Two switches are required to monitor the pressure in order to control changes to a high or a low oil pressure. The switches are not integrated in the instrument cluster. The engine control unit evaluates the signals from the oil pressure switches. If it becomes necessary to illuminate the warning lamp in the instrument cluster, a message is sent to the CAN data bus and the warning lamp in the instrument cluster is activated.

Oil pressure switch for reduced oil pressure







The switch for reducing the oil pressure closes when the oil pressure reaches 13 psi (0.9 bar). If the oil pressure falls below this range, the switch opens and the engine control module activates the warning lamp in the instrument cluster via the CAN bus. The oil pressure switch is installed in the main oil duct upstream of the oil filter module.

Oil pressure switch







The oil pressure switch operates within a pressure range that is higher than the switching threshold of the oil pressure control valve. The switch closes at an oil pressure of 36 psi (2.5 bar). The signal that the engine control module receives from the oil pressure switch indicates that the oil pump is generating the required oil pressure. The oil pressure switch is installed in the pressure oil duct downstream of the oil filter in the oil filter module.