Input factors for injection control

Determination of the engine speed and the crankshaft angle
The engine speed and the crankshaft angle are taken at the flywheel (1). For this purpose, on the circumference of the flywheel (1), there are 58 grooves (2). These are located up to a gap of 18 ° at intervals of 6 °.
The 18 ° groove is located between the 63 ° groove before top dead center (TDC) and the 45 ° groove BTDC of cylinders 1 and 6. They are used to detect the TDC of cylinders 1 and 6 and the angle position of the crankshaft.
Each groove (2) triggers an impulse in the crankshaft position sensor. As soon as the engine management control unit receives an impulse from the crankshaft position sensor, it starts an internal counter. Calculations yield the crankshaft position and the engine speed.
By calculating intermediate values, it is possible for the engine management control unit to determine the start of injection and injection duration accurately to within a fraction of a degree.

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Determination of the compression stroke at cylinder 1
The camshaft sprocket located on the intake camshaft (5) has 12 grooves (3). They are each distributed at intervals of 30° across the entire circumference of the camshaft sprocket (5). On the camshaft sprocket (5), there is an additional groove (4) before top dead center (TDC) of cylinder 1.
As soon as the intake camshaft turns, the grooves (3) and the additional groove (4) in the camshaft position sensor generate magnetic field changes. These are converted into shift signals by an electronic analysis system and passed on to the engine management control unit.
If the engine is started, the engine management control unit, with the help of the additional groove (4), checks when cylinder 1 is in its compression stroke.
The engine management control unit determines the position of the crankshaft at the same time via the crankshaft position sensor. It compares the position of the additional groove (4) to the position of the gap on the flywheel (1). Then, the signals of the crankshaft position sensor are sufficient to define the compression stroke of cylinder 1 and thus the start of actuation of the fuel injectors for cylinders 1 to 6 (Y608 to Y613).

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Determination of the fuel temperature
The fuel temperature is determined by the engine management control unit via the fuel temperature sensor.
In the fuel temperature sensor, there is a temperature-dependent resistance with negative temperature coefficients (NTC).
If the fuel temperature sensor malfunctions, the engine management continues to work with substitute values.

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Determination of the coolant temperature
For the fan regulation, the engine management control unit uses the measurement values of the inlet coolant temperature sensor and the outlet coolant temperature sensor.
For determining the start of actuation and the actuation duration (injection quantity) of the fuel injectors, the engine management control unit uses exclusively the measurement values of the outlet coolant temperature sensor.
In both the inlet coolant temperature sensor and the outlet coolant temperature sensor, there is a temperature-dependent resistance with negative temperature coefficients (NTC).
If one of the sensors malfunctions, the engine management control unit continues to work with substitute values. This allows the engine to be started even under unfavorable conditions and for the vehicle to continue to be driven.
To protect the engine from overheating, the engine management control unit limits the specified engine torque if the coolant temperature increases to an impermissibly high value.

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Determination of the air mass
Determination of the air mass occurs via the engine management control unit. It uses the information of the following sensors:

 Charge air pressure and temperature sensor in charge air pipe

 Temperature sensor downstream of air filter (vehicles with Euro VI standard)

 Charge air temperature sensor in charge air distributor

 Exhaust gas recirculation (AGR) differential pressure sensorFrom these values, the engine management control unit derives the air mass of the actual intake and supercharged fresh air and the value of the actual recycled exhaust.

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