PRE-RELEASE
Turbo pressure control
| Turbo pressure control |
The wastegate is a flap valve which closes or opens the "bypass" channel at the side of the turbine.
The flap valve is actuated by a solenoid valve and a diaphragm box. The diaphragm box is actuated by the turbocharger pressure and a spring in it closes the flap valve via a rod.
The solenoid valve controls the flow of air past the wastegate, having regard to the air mass/combustion ratio, so that it is always in keeping with what is requested.
At low and normal loads the wastegate for turbo pressure is closed. When the load increases and turbo pressure approaches maximum, the spring force is overcome and the valve opens the "bypass" channel, thus reducing the pressure.
The pressure is monitored continuously by a pressure sensor connected to the intake manifold by a hose.
The light turbo variant (B204E) has a control valve that opens at a predetermined pressure (0,45 bar), without being controlled by Trionic.
For further information on turbo control and the solenoid valve, se group 2, Engine management system.
