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23.9
Air/Fuel ratio control
The inlet air is compressed in the turbocharger, cooled to optimal level
in the charge air cooler and enters the charge air receiver in the engine
block. The air pressure in the receiver is controlled by a proportional
exhaust waste-gate valve located on the turbocharger support. The
valve reduces the turbocharger efficiency and controls thereby the air
pressure in the receiver. By adjusting this pressure, the
i.e. air/fuel
ratio in the cylinder is optimised.
The charge air pressure control is based on a PID-controller, which
compares the actual pressure with a mapped pressure reference table.
In this table, the reference is engine load dependent. The reference is
offset according to the charge air temperature.
If cylinder knock occurs in several cylinders simultaneously, another
offset will be added to the waste-gate reference, in order to achieve a
leaner air/fuel mixture in all cylinders. This process is continuous, and
the offset will be restored when the situation normalises.
Air/Fuel ratio control
Wastegate
valve
Engine
load
Receiver
temperature
I
t
MCU
- Engine speed
- Engine load
- Wastegate ref.
Profibus
P
I
kW
I
P
I
Receiver
pressure
Cylinder
knock
a
mV
Fig 23-16
3223030408
WECS 3000
34SG-200408-01
Содержание 41508
Страница 3: ......
Страница 12: ...Appendix B Welding Precautions 200147...
Страница 22: ...Fuel Lubricating Oil Cooling Water 34SG 200303 03...
Страница 29: ...A Ap pp pe en nd di ix x A A E En nv vi ir ro on nm me en nt ta al l H Ha az za ar rd ds s 2 20 00 03 32 21 1...
Страница 73: ...Maintenance Tools 32 9801...
Страница 115: ...Engine Block with Bearings Cylinder and Oil Sump 34SG 9701...