Pic. 2.209. Boost pressure control solenoid valve: 1 – pneumatic actuator; 2 - solenoid valve
The pneumatic actuator of the boost pressure regulator is controlled by a solenoid valve according to the commands of the injection computer (pic. 2.209).
The boost pressure regulator is controlled by a solenoid valve in response to commands from the injection computer.
In the initial position, the boost pressure regulator valve is closed and the solenoid valve is open.
In the open position, the solenoid valve connects the outlet of the turbocharger (boost pressure) pneumatically actuated, so the boost pressure acts directly on the pneumatic actuator and the pressure regulator valve opens.
When the solenoid valve is controlled, the boost pressure signal (measured at the outlet of the turbocharger) supplied to the turbocharger. Consequently, boost pressure is removed from the pneumatic actuator and the pressure regulator valve closes.
After starting the engine, the supply voltage is supplied to the solenoid valve, which is open in the initial position. However, for a certain period of time, the duration of which depends on the temperature of the coolant, the boost pressure is limited and the engine speed cannot exceed 2500 min–1.
This is necessary so that the oil has time to flow to the turbocharger bearings.
Pic. 2.210. Boost pressure control circuit