VDOP System Description

The variable displacement oil pump consists of a control ring (3), a chamber A (4), a chamber B (5), a vane (6), a rotor (7), a chamber spring (8) and a case (9).

At engine stop, the control ring is positioned on the left in figure below. After the engine starts, oil pump capacity changes in accordance with movement of the control ring. When the eccentricity between the rotor and the control ring increases, the oil pump capacity increases, and when the eccentricity decreases, the oil pump capacity also decreases.

The relief valve or VDOP solenoid valve releases the pressure in the oil pressure chamber A (P2) to control the movement of the control ring.

Oil pressure P1 is applied to chamber B, while oil pressure P2 as well as the chamber spring force is applied to chamber A. In this condition, the control ring is positioned on the left.

When the output oil pressure P1 (1) exceeds a specified value, and exceeds the spring force of the relief valve spring (2), the relief valve (3) opens to release the oil pressure in chamber A (4). As the oil pressure in chamber A decreases and the pressure in chamber B (5) exceeds the chamber spring force (6) and pressure P2 (7), the control ring (8) moves to the right in figure below. Accordingly, the oil pump capacity decreases and the oil pressure increase is limited and controlled oil pressure remains HIGH.

When the ECM determines that high pressure is not required, it releases the pressure in chamber A (1) by opening the VDOP solenoid valve (2). As the oil pressure in chamber A decreases and the pressure in chamber B (3) exceeds the chamber spring force and pressure P2, the control ring (4) moves to the right. Accordingly, the oil pump capacity decreases and the oil pressure increase is limited and controlled oil pressure is LOW.

Oil pressure switch-1 turns the oil pressure warning light on and off in the combination meter. Switching pressure level of oil pressure switch-2 is set higher than that of oil pressure switch-1. The ECM monitors proper operation of the VDOP solenoid valve and the oil pump based on the signal from oil pressure switch-2.