Location
The hydraulic constant throttle solenoid valve is located on the left side of the engine.
Shown on engine 926.9 |
Y49 | Hydraulic constant throttle solenoid valve |
W01.50-1041-06
Task
The hydraulic constant throttle solenoid valve controls the hydraulic constant throttles in the cylinder head.
Function
The hydraulic constant throttle solenoid valve is designed as a 3/2-way valve and is connected via a bore on the oil circuit of the engine. In the rest position, it blocks the oil pressure to the constant throttles.
The engine management (MR) control unit (A6) actuates the hydraulic constant throttle solenoid valve directly. As soon as the hydraulic constant throttle solenoid valve is actuated, it opens a feed hole to the control line of the throttle valves (constant throttles), which are then opened by the oil pressure of the engine.
Because of the high compression of the 6-cylinder engines, pressure pulses are produced in the control line as a result of the cylinder backpressure on the open throttle valves (constant throttles). So that the throttle valves (constant throttles) remain open, a pressure regulating valve in the feed hole prevents oil from flowing back.
After the engine management (MR) control unit has ended the actuation of the hydraulic constant throttle solenoid valve, the hydraulic constant throttle solenoid valve closes and an integrated return channel opens as a result. The oil in the control line is forced back along the return hole into the crankcase as a result of the throttle valves (constant throttles) closing.
Effect
The constant throttles act to reduce the compression pressure in the power stroke (3rd cycle); essentially nothing is affected during compression (2nd cycle).