There are three main types: magnetoelectric induction type, Hall effect type and photoelectric type. The working principles of the three types are:
1. Magnetoelectric induction type:
Magnetoelectric induction speed sensor and crankshaft position sensor are installed in the distributor in two layers. 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, and the speed rotor has 24 teeth. The permanent magnet induction detection coil is fixed on the distributor body. If the speed sensor signal, crankshaft position sensor signal and the working sequence of each cylinder are known, the crankshaft position of each cylinder can be known. 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 type:
Hall effect type speed sensor and crankshaft position sensor are signal generators using Hall effect. The Hall signal generator is installed in the distributor, coaxial with the distributor head, and fixed on the distributor disk by 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 notch 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 panel with light holes. The signal disk rotates with the distributor shaft photoelectrically, and there are 36 photoetching gaps in the outer ring of the signal disk, which generates the signal of crankshaft rotation angle of 1; There are six smooth holes evenly distributed at intervals of 6 in the slightly inner part, which generate signals of crankshaft rotation angle of 12, and one smooth hole is wide, which is used to generate signals relative to top dead center of cylinder 1. The signal generator is installed on the distributor shell 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 disk, the phenomenon of alternating light transmission and light shielding occurs. When the light beam of the light emitting diode hits the photosensitive diode, the photosensitive diode generates voltage; When the light-emitting diode beam is blocked, the photodiode voltage is . After being shaped and amplified by the circuit, these voltage signals are sent to the electronic control unit when the crankshaft angle is 1 and 12, and the electronic control unit calculates the engine speed and crankshaft position according to these signals.
The crankshaft position sensor is usually installed in the distributor and is one of the most important sensors in the control system. Its functions are: detecting engine speed, so it is also called speed sensor; It detects the top dead center position of the piston, so it is also called the top dead center sensor, including detecting the top dead center signal of each cylinder for controlling ignition and the top dead center signal of the first cylinder for controlling sequential fuel injection.