Engine - System Operation and Component Description: Operation
| Item | Description |
|---|---|
| 1 | Oil pressure from the main oil gallery |
| 2 | Oil pump control solenoid |
| 3 | Leakage line |
| 4 | Oil sump |
| 5 | Pressure relief valve |
| 6 | Spring |
| 7 | Oil pressure to oil filter |
| 8 | Pressure port of the vane pump |
| 9 | Hydraulic control piston |
| 10 | Control chamber |
| 11 | Adjusting ring, vane pump |
The oil pressure is controlled via a hydraulically operated control piston integrated into the oil pump. The pressure on the control piston is determined by a solenoid valve which is activated by the PCM according to the requirements.
In the rest position, the solenoid valve is closed (see previous illustration). The engine oil supplied by the oil pump flows to the control chamber. Because the solenoid valve is closed, the oil flows through the control chamber and drains to the oil pan via a bypass in the solenoid valve. No pressure can therefore be built up in the control chamber.
The control piston is pushed to the left by the spring force. Because of this, the control piston closes the oil gallery to the vane-cell pump adjusting ring.
In this position, the pressure gallery of the transfer pump has the largest aperture cross-section . The maximum possible oil flow is thus available for engine lubrication.
| Item | Description |
|---|---|
| 1 | Oil pressure from the main channel |
| 2 | Oil pressure control solenoid valve |
| 3 | Leakage line |
| 4 | Oil sump |
| 5 | Pressure relief valve |
| 6 | Spring |
| 7 | Oil pressure to oil filter |
| 8 | Pressure channel of the transfer pump |
| 9 | Hydraulic control piston |
| 10 | Control chamber |
| 11 | Adjusting ring, vane pump |
When operating conditions permit the vehicle to be driven with a lower oil pressure, the PCM opens the solenoid valve .
The oil pressure supplied by the oil pump now acts directly and via the solenoid valve on the control chamber and with it pushes the control piston to the right against the spring force.
Because of this, the control piston opens the oil channel to the vane-cell pump adjusting ring. The pump pressure now acts on the adjusting ring and presses it towards the center of the pump.
In this position, the pressure channel of the transfer pump has only a small aperture cross-section . A lower oil pressure is thus available for engine lubrication.