Crankshaft Sensor

Crankshaft Sensor

Crankshaft sensor
The crankshaft sensor is attached to the gearbox case.
The crankshaft sensor records the position of the crankshaft with the aid of an increment wheel screwed to the crankshaft. The engine control uses this to calculate the engine speed. The crankshaft sensor and camshaft sensor are necessary for the fully sequential fuel injection (fuel injection takes place individually for each cylinder at the specific ignition point).
The signal from the crankshaft sensor means that the engine control also evaluates the crankshaft acceleration.
The crankshaft acceleration provides an indication of the combustion quality of individual cylinders.

Functional description
The increment gear has 58 teeth as well as a reference gap of 2 teeth.
The reference gap enables detection of the upper dead centre of the 1st cylinder. By monitoring the individual teeth, the Hall effect sensor delivers a certain number of signal jumps to the engine control system.







The engine control unit uses the scanned tooth flanks to calculate the duration and length of a crankshaft revolution.
The time that the increment wheel requires to rotate past the hall effect sensor is referred to as the crankshaft revolution per time.

For starting the engine, the engine control unit checks the following preconditions:
- error-free signal from the crankshaft sensor and camshaft sensor
- both signals must be detected in a specific chronological sequence

This process is referred to as synchronization and is only performed when the engine is started. It is only the synchronization process that enables the engine control unit to activate fuel injection correctly. The engine will not start without synchronization.
If the crankshaft sensor signals fails (with the 1st crankshaft revolution) or an invalid synchronization is detected for the engine start, the diagnosis starts immediately. The camshaft sensor signals are read here. If 12 flanks on the camshaft are read and the fault is still there, a fault is stored.
As soon as no crankshaft sensor signals are received or there is no valid synchronization with the engine running, debouncing starts.

Structure and inner electrical connection
The measuring procedure is based on Hall IC. The hall effect sensor is magnetically pre-tensioned by means of a permanent magnet. The Hall integrated circuit supplies an output voltage that is proportional to the magnetic field.







Characteristic curve and setpoint values
The transition from a high phase to a low phase indicates a falling tooth flank. The engine control only counts the falling tooth flanks. The difference between 2 falling tooth flanks is a crank angle of 6°.







Observe the following setpoint values for the crankshaft sensor:

Size Value
Voltage range 6 to 16 Volts
Engine speed range up to 8000 rpm
Air gap range 0.1 to 1.8 mm
Maximum output current 20 mA
Ambient temperature -40 °C to 160 °C

Diagnosis instructions

Failure of the component
If the crankshaft sensor fails, the following behavior is to be expected:
- Fault entry in the engine control unit
- Emergency operation with substitute value

We can assume no liability for printing errors or inaccuracies in this document and reserve the right to introduce technical modifications at any time.