Turbo Control Valve, WASTEGATE

Courtesy of VOLVO CARS CORPORATION

Turbo control valve wastegate has the task of allowing a certain proportion of the exhaust gases past the turbocharger turbine, above a certain pressure which leads to the pressure being relieved and the boost pressure being limited to the desired boost pressure.

By controlling the valve the Engine Control Module (ECM) can choose when the valve opens, that is at what pressure, and in this way create boost pressure without being too limited by the actual flow of exhaust gases.

Turbo control valve wastegate creates a vacuum that is proportional to the size of its control signal. This variable vacuum is translated into mechanical motion via a vacuum tank.

The valve is split into a pneumatic and an electronic part. Both are linked through a double functioning valve.

By increasing the control current, the electromagnetic force also increases proportionally and the armature moves upwards and opens the inner valve. The amount of vacuum increases until the pneumatic force is as great as the electromagnetic force that is obtained when a neutral position for the valve is achieved. If the control current increase, the outgoing vacuum increases and the pneumatic unit opens.

If the control current is reduced, the pneumatic force dominates and while the armature moves in the opposite direction, the outer valve opens. The amount of vacuum reduces until a new balance is found and that the neutral position is achieved.

Turbo control valve is controlled by the Engine Control Module (ECM) via a Pulse Width Modulated (PWM) signal.

The valve is diagnosed by the Engine Control Module (ECM) and the requested position can be read off.