P05.20-A049-79
Example illustration of engine 264 |
1 | Exhaust camshaft solenoid | 2 | Intake camshaft solenoid |
Overview
This document contains information on:
General
Function
General
The adjustment solenoids actuate the control pistons of the camshaft positioners, which then adjust the camshafts.
Function
The adjustment solenoids are actuated by the combustion engine control unit at the ground end with a pulse width modulated signal. The control plungers of the camshaft positioners are actuated via map-dependent duty cycle of the pulse width modulated signal.
For fast adjustment of the camshafts, the duty cycle of 100 % (maximum amperage) is briefly output. A hold-in winding voltage with a smaller duty cycle is then set (lower current strength).
Depending on the position of the control plungers, more or less engine oil flows out of the hollow camshafts into the pressure chambers of the camshaft positioners. This is achieved by bore holes located at various points on the control plungers and by oil ducts in the camshaft positioner.
The camshaft positioners adjust the camshafts according to their engine oil level. If the solenoids are no longer actuated, the camshaft positioner is reset using spring force. The camshaft adjustment range is mechanically restricted by the shape of the camshaft positioners.
The following positions of the control plunger are possible:
Fill pressure chambers
Engine oil flows from the hollow camshafts into the camshaft positioners. The camshafts adjust to the respective direction of rotation. The intake camshafts adjust to "advanced". The exhaust camshafts adjust due to their reverse direction of rotation to "retarded".
Close pressure chambers
A camshaft Hall sensor detects the camshaft positions of each camshaft. Once the required adjustments are reached, the respective solenoids are actuated such that the pressure chambers in the camshaft positioners are closed.
Empty pressure chambers
The camshafts adjust themselves through spring load against their direction of rotation.