P09.50-2115-79
Example illustration of engine 608 |
1 | Boost pressure positioner | 2 | Turbocharger |
Overview
This document contains information on:
General
Location
Function
General
The boost pressure regulator changes the boost pressure by altering the position of the guide vanes in the exhaust gas turbocharger with variable turbine geometry. The boost pressure regulator is actuated via a vacuum cell or an electric actuator motor.
Location
The boost pressure regulator is located directly on the exhaust gas turbocharger with variable turbine geometry.
Function
The vacuum unit or the electric actuator motor actuates an adjusting ring which adjusts the guide vanes mounted in the carrier ring. The guide vanes influence the exhaust flow that acts on the turbine wheel. At low rpms, the inlet cross-section is reduced. Reducing the inlet cross-section increases the exhaust gas speed and the turbine speed. This enables the required boost pressure to be achieved even at low rpms without any power dip. At high rpm, the inlet cross-section is increased so that the turbine wheel does not rotate too quickly and the boost pressure is not too large. The regulation ensures that maximum boost pressure is achieved quickly and is maintained over a wide rpm range.
If faults occur, e.g. a faulty pulse width modulated signal, the boost pressure regulator moves to the limp-home position. In the limp-home position, the boost pressure regulator opens the largest inlet cross-section. This restricts the amount of engine output available.
Boost pressure control of the exhaust gas turbocharger with variable turbine geometry improves the torque characteristics in full-load operation and under partial-load conditions. The specified value for the boost pressure depends on the following variables:
Rpm
Quantity injected
Coolant temperature
Intake air temperature
Atmospheric pressure