The electromagnetic induction crankshaft camshaft position sensor is mainly composed of rotor (namely trigger gear), permanent magnet, iron core and induction coil (as shown in Figure 2-25).

2. Hall crankshaft and camshaft position sensor

When a Hall semiconductor substrate with current (that is, a Hall element) is placed in a magnetic field perpendicular to the current direction, a tiny voltage will be generated in the direction perpendicular to the current and the magnetic field, which is called Hall voltage. Hall voltage UH is proportional to current I and the strength b of external magnetic field.

Where: RH- Hall coefficient;

D —— thickness of the d——Horky part.

Hall sensor has two outstanding advantages: first, the output voltage signal is similar to a square wave signal; Second, the output voltage has nothing to do with the rotational speed of the measured object. Hall effect sensor is different from electromagnetic induction sensor, which needs external power supply.

Some cars (such as Cherokee Jeep, etc. ) Use a differential Hall sensor. The differential Hall sensor, also known as the dual Hall sensor, has the same basic working principle as the Hall sensor, and the output voltage of the sensor is formed by superposition of two Hall signals.

3. Photoelectric crankshaft and camshaft position sensors

The photoelectric sensor is mainly composed of a signal rotor with blades and a signal generator, which includes a light emitting diode, a phototransistor and an amplification and shaping circuit.

Photoelectric sensor has the advantages of high indexing accuracy and digital pulse signal output, but it also has the disadvantage of high requirements for the use environment.