Charging, Function - GF09.00-P-2000KJ
ENGINE 281.910 in MODEL 453.0/3/4
Function requirements for charging - general
- Circuit 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 compressor outlet in the charge air pipe to the charge air cooler and then onto the charge air distributor.
The high rpm of the compressor impeller and the resulting high volumetric flow rate compresses the air in the charge air pipe.
View of engine from rear left
View of engine from the front
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 controlling the charge air cooler circulation pump
Function sequence for boost pressure control
The boost pressure control takes place electronically over the boost pressure control flap actuator (M16/7). The engine boost pressure control is actuated characteristics map and load-dependent by the ME-SFI [ME] control unit for boost pressure control. To do this the ME-SFI [ME] control unit evaluates the following sensor signals and functions of the engine management:
- Intake air temperature sensor (B17) (Charge air temperature upstream of throttle valve or charge air cooler)
- Charge air temperature sensor (B17/8) (Charge air temperature downstream of charge air cooler)
- Pressure sensor downstream of throttle valve (B28/7), boost pressure
- Accelerator pedal sensor (B37), load request made by driver
- Crankshaft position sensor (L5), engine speed
- Actual value potentiometer 1 (M16/6r1) and actual value potentiometer 2 (M16/6r2) on throttle valve actuator (M16/6)
In wide open throttle operation, maximum boost pressure builds up. In order to reduce the boost pressure, the exhaust flow for driving the turbine wheel is diverted via a bypass on the turbine wheel by opening the boost pressure control flap.
The boost pressure control flap actuator is controlled by the ME-SFI [ME] control unit. The throttling at high rotational speeds takes place by means of the linkage at the boost pressure control flap actuator.
Function sequence for charge air cooling
The compressed charge air flows over the charge air pipe and the throttle valve actuator to the charge air distributor. There is a charge air cooler cooled by coolant (water charge air cooler) integrated in the charge air distributor. This then cools the charge air heated up by the compression and routes it directly into the engine.
Function sequence for controlling the charge air cooler circulation pump
For cooling the charge air, the charge air cooler circulation pump (M44) delivers the coolant from the front cooler to the charge air cooler in the engine. As required the ME-SFI [ME] control unit switches the charge air cooler circulation pump on or off. As a reference for controlling the charge air cooler circulation pump, the ME-SFI [ME] control unit, amongst other things, reads in the signals of the intake air temperature sensor (charge air temperature upstream of throttle valve or charge air cooler) and the charge air temperature sensor (charge air temperature downstream of charge air cooler). Through controlling the charge air temperature it is possible, amongst other things, to reduce the exhaust emissions and the efficiency of the engine is increased.
Model 453.062/362/462 BRABUS
Vehicles with code ICBA (BRABUS) are fitted with a powerful charge air cooler circulation pump actuated over pulse width modulation (PWM). This can be actuated continuously rpm regulated by the ME-SFI [ME] control unit.
Vehicle view from the lower front (except model 453.062/362/462 BRABUS with code ICBA (BRABUS))
Vehicle view from the lower front (model 453.062/362/462 BRABUS with code ICBA (BRABUS))
| Electrical function schematic for charging | PE09.00-P-2050-97BBA | ||
| Overview of system components motor electronics (ME-SFI) fuel injection and ignition system | GF07.61-P-9997KJ |