PRE-RELEASE
Camshaft control device system, description, E39
| Camshaft control device system, description, E39 |
| Camshaft position regulation (CMP) |
Regulation of the variable camshaft system takes place by means of an electrohydraulic device which is used to improve engine performance and properties over a broad range.
These improvements include lower exhaust emission thanks to dilution with exhaust gases in the combustion chamber charge (internal EGR), broader torque registers and improved fuel economy.
The control system achieves this by changing the angles of the camshafts or the camshaft setting in relation to the crankshaft position. Control devices quite simply permit earlier or later opening of intake and exhaust valves during the entire engine four-stroke cycle. On the other hand, the control devices are unable to change the opening durations of the valves or their cam lift.
With the engine off, idling or during the shutdown phase, the camshafts' control devices are locked in park mode. Inside the control device unit is a return spring and a locking pin. When the camshaft is not being actuated by the control device, the return spring turns the camshaft back to park mode and the locking pin holds the control device sprocket against the camshaft.
| Function, control device system |
The variable camshaft system's control device is controlled by the ECM, control module, E39 (590).
The ECM sends a signal to a solenoid valve to control the oil flow to the ducts of the camshaft control device. Engine oil under pressure is supplied in order to release the locking pin and on to the wing and rotor unit in the control device.
There are two ducts for the oil flow, one for moving the camshaft forwards and one for moving it back. The camshaft control device is fitted on the camshaft and is controlled hydraulically in order to change the angle of the camshaft in relation to the crankshaft position.
The pressure, viscosity and temperature of the engine oil, as well as the oil level, may have an adverse effect on the performance of the camshaft control device.
