Functional Description of EGM
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Status September 2003 (EvoBus-Service / AFT)
Page: 17 of 83
2.2.1.3
Engine protection: turbocharger overpressure
The engine protection function turbocharger overpressure is used to protect the engine during operation
against impermissibly high boost pressures ("turbocharger overpressure"), e.g. in case of a defective
"wastegate".
•
Turbocharger overpressure detection
If the actual boost pressure is above the permissible value of 2.35 bar for longer than 15 seconds,
then the event "Boost pressure too high" is detected and the fault code 1820 is entered. This limit
pressure check takes place cyclically every 40 ms. An active overpressure fault is first reset in the
engine state "Engine stopped" with the engine stopped. If the boost-pressure only briefly exceeds the
currently permissible value, the fault debouncing begins again from the start the next time the limit is
exceeded.
•
Torque limitation
The full-load torque is limited by a factor dependent on the boost pressure to protect the turbocharger
and the engine.
Engine protection: turbocharger overpressure
Boost pressure
Torque limitation with
turbocharger overpressure
Engine protection: overpressure limitation
File: kd_mts_p2.vsd
Date: 29.09.2000
Boost pressure
Limitation torque
Characteristic curve
MOB - Torque limitation with charge-air overpressure
Max. target torque [Nm] = f(Boost pressure [bar])
Torque
Boost pressure
