Crankshaft position sensor is usually installed on the distributor and is one of the most important sensors in the control system. Its function is to detect the engine speed, so it is also called speed sensor; It detects the top dead center position of the piston, so it is also called top dead center sensor, which includes detecting the top dead center signal of each cylinder for controlling ignition and detecting the top dead center signal of the first cylinder for controlling sequential fuel injection.

Crankshaft sensors mainly include magnetoelectric induction type, Hall effect type and photoelectric type.

1, magnetoelectric induction type:

Magnetoelectric induction speed sensor and crankshaft position sensor are installed on the upper and lower floors of the distributor. The sensor consists of permanent magnet induction detection coil and rotor (timing rotor and speed rotor), and the rotor rotates with the distributor shaft. The timing rotor has one, two or four teeth, while the speed rotor has 24 teeth. The permanent magnet induction detection coil is fixed on the distributor body. If we know the speed sensor signal, the crankshaft position sensor signal and the working sequence of each cylinder, we can know the crankshaft position of each cylinder. The rotor signal disk of the magnetoelectric induction speed sensor and the crankshaft position sensor can also be installed on the crankshaft or camshaft.

2. Hall effect formula:

Hall effect speed sensor and crankshaft position sensor are signal generators using Hall effect. Hall signal generator is installed in the distributor, coaxial with the distributor head, and fixed on the distributor through the packaged Hall chip and permanent magnet. The number of notches on the trigger impeller is the same as the number of engine cylinders. When the blade on the trigger impeller enters between the permanent magnet and the Hall element, the magnetic field of the Hall trigger is bypassed by the blade, so that Hall voltage is not generated and the sensor has no output signal. When the gap on the trigger impeller enters between the permanent magnet and the Hall element, the magnetic field lines enter the Hall element, the Hall voltage rises, and the sensor outputs a voltage signal.

3, photoelectric type:

The photoelectric crankshaft position sensor is generally installed in the distributor and consists of a signal generator and a signal disk with a light hole. The signal disk rotates with the distributor shaft, and the outer ring of the signal disk has a 360 photoetching gap, which generates a signal of1crank angle; There are six smooth holes evenly distributed at an interval of 60, which generate a crank angle signal of 120, in which 1 smooth hole is wider and is used to generate a signal relative to 1 cylinder top dead center. The signal generator is installed on the shell of the distributor and consists of two light-emitting diodes, two photosensitive diodes and a circuit. The light emitting diode is facing the photosensitive diode. The signal disk is located between the light emitting diode and the photosensitive diode. Because there are light holes on the signal plate, there is an alternating phenomenon of light transmission and shading. When the light beam of the light emitting diode hits the photosensitive diode, the photosensitive diode generates voltage; When the light beam of the LED is blocked, the voltage of the photodiode is 0. These voltage signals are shaped and amplified by the circuit and sent to the electronic control unit when the crank angle is 1 and 120. The electronic control unit calculates the engine speed and crankshaft position according to these signals.