Turbocharging, function

P09.00-2035-76

Recirculated air flap closed,

Compressor actuated

50 Compressor

110/2 Charge air cooler

B17/8 Charge air temperature sensor

B28 Pressure sensor (charge air)

M16/6 Throttle valve actuator

M16/7 Air recirculation flap actuator
(for model 230 at first from 07/2002)

Y2/1 Supercharger magnetic clutch

P09.00-2033-76

Recirculated air flap open,

Compressor not actuated

50 Compressor

110/2 Charge air cooler

B17/8 Charge air temperature sensor

B28 Pressure sensor (charge air)

M16/6 Throttle valve actuator

M16/7 Air recirculation flap actuator
(for model 230 at first from 07/2002)

Y2/1 Supercharger magnetic clutch

Charging increases the performance of the engine in the upper partial loading and full loading ranges.

The compressor (50) compresses the intake air and therefore increases the degree of filling of the cylinder.

The metered fuel quantity is increased as a result of the rise in the air quantity. This increases the torque produced and the engine performance.

The charge air cooler (110/2) lowers the charge air temperature and thus improves the degree of filling of the cylinder. This increases engine output, reduces fuel consumption and lowers the exhaust gas temperature. A low exhaust gas temperature means low NOX issues.

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Function

The drive power needed to drive the compressor is taken from the crankshaft over a separate belt drive.

The magnetic coupling of the mechanical supercharger (Y2/1) is responsible for switching the compressor on and off.

The magnetic clutch is actuated map-controlled by the ME-SFI [ME] control unit (N3/10) if a high engine torque is requested.

The compressor is always actuated for technical reasons from an engine speed of about 3500 rpm.

The charge air pressure is regulated by the recirculated air flap actuator (M16/7) which is directly controlled by the ME control unit in accordance with the performance map. In the case of a switched off supercharger the intake air can circumvent the compressor via the air recirculation flap. The air can be suctioned in directly in such a way that the supercharger does not have to turn. This means that the fuel consumption is reduced during idling and in the partial loading range.

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The opening angle of the recirculated air flap changes in the opposite direction to the opening angle of the throttle valve. This means: if the throttle valve open by 20° for example then the air recirculation flap closes by 20°. The recirculated air flap is completely closed at full load (maximum charge pressure) while the throttle valve is wide open (maximum intake air).

The charge air temperature and the charge air pressure are measured in the charge air distributor pipe and sent to the ME control unit in order to allow adjustment of the correct fuel quantity for the degree of filling of the cylinder.

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The compressor is switched on shortly when starting at external temperatures below 0°C in order to free up the compressor from any icing which may have occurred (through the presence of condensate in the compressor).