GF30.35-W-3002A | Function of the specified engine torque calculation | 4.7.07 |
ENGINE 904.9 in MODEL 375.1 with BODY 375.830
ENGINE 904.9 in MODEL 970, 972, 975, 976 with BODY 972.899
ENGINE 906.9 in MODEL 970, 972, 974, 975, 976 with BODY 972.899
ENGINE 906.9 in MODEL 375.3 with BODY 375.810
ENGINE 906.9, 926.9 in MODEL 950, 952, 953, 954 with BODY 940.899
General information
The specified engine torque is a purely calculated value based on the driving requirements of the driver.
This value is primarily dependent upon the position of the gas pedal and mainly needed by the engine control (MR) for regulating the load while driving.
This specified engine torque can, however, be limited in the drive control (FR),
for example to maintain the legally prescribed maximum speed or for a regulating intervention by the Antilocking systems (ABS) or the Acceleration Slip Regulation (ASR), and in the engine control (MR), for example to protect the engine.
Function
The drive control (FR) first determines the gas pedal position. This occurs with the aid of an electronic foot throttle actuator which detects the position of the gas pedal and converts this into PWM (pulse-width-modulated) signals.
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These PWM signals are sent to the drive control (FR) control unit which derives the specified engine torque from them.
Further to the gas pedal position, the drive control (FR) also observes other peripheral conditions such as the legally prescribed maximum speed or a regulating intervention by the Antilocking systems (ABS) or the Acceleration Slip Regulation (ASR).
This means that the drive control (FR) can limit the specified engine torque according to the vehicle speed or according to the condition of the Antilocking System (ABS) or the Acceleration Slip Regulation (ASR).
The specified engine torque is also always selected within the scope of the maximum possible engine torque which is again determined by the engine control (MR) and sent via the engine CAN bus to the drive control (FR).
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the maximum possible engine torque is primarily dictated by the data set in the MR electronics and is thus dependent on the model of the engine. It can also be additionally limited, however, according to the operating conditions of the engine (engine temperature, speed etc.).
The specified engine torque, which has been calculated and then limited in this way, is finally sent via the engine CAN bus to the engine control (MR).
The specified engine torque is further limited in the engine control (MR) as required (for example to protect the engine) and corrected, while taking account of the actual mass of fuel which can be derived from the fuel temperature, before the feed or injection beginning point and the delivery end of the unit pumps are finally calculated.
The specified engine torque calculated by the drive control (FR) is not always positive:
If the gas pedal is in the idling position, the specified engine torque is "0".
It can even be negative during a thrust operation.