Pressure Control: Notes

The oil pressure control valve in the oil pump has two functions:

1. Deactivates stage two oil pump circuit above 2 bar. Stage two is only active in the lower speed range. This is to ensure that there is always sufficient oil pressure for the VANOS units even at high oil temperatures and low speeds. The oil pump power consumption is reduced by deactivating stage two.
2. Monitoring the required oil pressure for the engine. The piston in the control valve is moved by a spring against the engine control pressure which is returning from the engine. This means that precise monitoring of the actual engine oil pressure is possible.

A separate pressure relief valve in the oil pump automatically opens at the maximum pressure of approximately 15 bar. This prevents damage in the oil pump especially at low oil temperatures  .