Function requirements for charging - general
Terminal 87 (engine management) ON
Engine runs
Forced induction, general
The cylinder charging efficiency is improved as a result of forced induction. This raises the engine torque and engine power output. The fuel quantity corresponding to the increased air mass is metered by the ME-SFI [ME] control unit (N3/10). During forced induction, the flow energy of the exhaust gases is used to drive the ATL.
The ATL draws in fresh air via the air filter at the compressor inlet and leads this via the charge air cooler into the compressor outlet to the charge air pipe.
The high rpm of the compressor impeller and the resulting high volumetric flow rate compresses the air in the charge air pipe.
Forced induction function sequence
The function sequence is divided into the following subfunctions:
Function sequence for boost pressure control
Function sequence for charge air cooling
Function sequence for boost pressure control
The boost pressure control occurs electropneumatically over the boost pressure control pressure transducer (Y31/4). The pressure transducer is actuated dependent on the characteristics map and the load by the ME-SFI [ME] control unit (N3/10) for the purposes of boost pressure control. To this end, the ME-SFI [ME] control (N3/10) analyses the signals from the following components:
Temperature sensor downstream of charge air cooler (B17/8), charge air temperature
Intake manifold pressure sensor (B28/15), intake pressure
Boost pressure sensor (B5/1), boost pressure
Accelerator pedal sensor (B37), load request made by driver
Crankshaft Hall sensor (B70), engine rpm
Actual value potentiometer 1 (M16/6r1) and actual value potentiometer 2 (M16/6r2), throttle valve position
In wide open throttle operation, maximum boost pressure builds up. To reduce the boost pressure, the exhaust gas flow for driving the turbine wheel is directed past the turbine wheel by opening a waste gate.
The boost pressure control flap vacuum cell has overpressure applied from the compressor side. The throttling at high rotational speeds takes place by means of the linkage at the boost pressure control flap vacuum cell.
Function sequence for charge air cooling
The compressed charge air flows via the charge air pipe to the charge air cooler. It cools the charge air heated by compression and directs it via the charge air pipe to the charge air distributor.
Referenced documents
- gf0770s9998d Overview of system components for gasoline injection and ignition system with direct injection