Component description for the turbocharger - GF09.40-P-4010P

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ENGINE 642 in MODEL 203.0 /2, 209.3 /4, 221.0 /1

ENGINE 642 up to 31.5.06 in MODEL 211.0 /2 /6, 219.3 up to 31.5.06

ENGINE 642 in MODEL 164.1 /8, 251.0 /1 except CODE (494) USA version

ENGINE 642 in MODEL 461.3, 463.3

Fig 1: Identifying Turbocharger

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Location

The turbocharger sits at the rear between the two cylinder heads.

Task

The turbocharger has the task of pre-compressing the suctioned in air depending on the operating condition of the engine.

Design

Fig 2: Identifying Turbocharger Components And Operation

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Function

The exhaust gases of the engine are directed through the exhaust manifold into the turbine housing onto the turbine wheel. The flow energy of the exhaust gases sets the turbine wheel in rotation. As a result, the compressor wheel, which is connected to the turbine wheel by the turbine shaft, is also driven at the same speed. The fresh air inducted by the compressor wheel is compressed and passed to the engine. The boost pressure is regulated by adjusting the guide vanes which means changing the turbine geometry. The pilot studs on the boost pressure positioner control rods (Y77/1) turn the adjusting ring in the turbine housing. As the pilot studs of the guide vanes also latch into the adjusting ring, all guide vanes are thus adjusted simultaneously.

At a lower engine speed the flow cross-section is downsized by closing the guide vanes. As a result, the flow rate of the exhaust gas at the turbine wheel is increased, which in turn increases the speed of the exhaust turbocharger and thus boosts the boost pressure.

At higher engine speeds, the guide vanes are opened increasingly and thus the flow cross-section increased. As a result, the flow rate of the exhaust gas at the turbine wheel is decreased, which in turn decreases the speed of the exhaust turbocharger and thus lowers the boost pressure.

Adjustment of the turbine geometry of the turbocharger takes place via the boost pressure positioner.