Classification of crankshaft position sensors
1. Inductive type
The magnetoelectric induction speed sensor and crankshaft position sensor are installed in two layers, upper and lower, inside the power distributor. The sensor consists of a permanent magnet induction detection coil and a combined rotor (timing rotor and speed rotor), which rotates together with the distributor shaft. The timing rotor has one, two, four or more teeth, while the speed rotor has 24 teeth. The permanent magnet induction detection coil is fixed on the distributor body. If the speed sensor signal and crankshaft position sensor signal, as well as the working sequence of each cylinder, are known, the crankshaft position of each cylinder can be determined. The rotor signal plate of the magneto electric induction speed sensor and crankshaft position sensor can also be installed on the crankshaft or camshaft.
2. Hall effect type
The Hall effect type speed sensor and crankshaft position sensor use the Hall effect to generate signals.
The Hall signal generator is installed inside the distributor, coaxial with the distributor head, and fixed as a whole on the distributor panel by encapsulated Hall chips and permanent magnets. The number of teeth on the trigger impeller is the same as the number of cylinders in the engine. When the tooth root on the impeller is triggered to enter between the permanent magnet and the Hall element, the magnetic field of the Hall trigger is bypassed by the tooth, and no Hall voltage is generated, causing no output signal in the sensor; when the tooth tip is triggered to enter between the permanent magnet and the Hall element, the magnetic field line enters the Hall element, and the Hall voltage increases, causing the sensor to output a voltage signal.
3. Photoelectric type
The photoelectric crankshaft position sensor is generally installed inside the power distributor and consists of a signal generator and a signal plate with a light hole.
The signal plate rotates together with the distributor shaft, and there are 360 photolithography gaps on the outer ring of the signal plate, generating a signal of a crankshaft angle of 1°; there are 6 light holes evenly spaced 60° apart slightly inside, generating a signal of a crankshaft angle of 120°. One of the light holes is wider, used to generate a signal corresponding to the top dead center of cylinder 1. The signal generator is installed on the distributor housing and consists of two light-emitting diodes, two photosensitive diodes, and a circuit. The light-emitting diode faces the photosensitive diode. The signal panel is located between the light-emitting diode and the photosensitive diode. Due to the presence of light holes on the signal panel, there is an alternating change in light transmission and blocking. When the beam of the light-emitting diode illuminates the photosensitive diode, the photosensitive diode generates a voltage; when the light emitting diode beam is blocked, the voltage of the photodiode is 0. These voltage signals, after being processed by the circuit, are transmitted to the electronic control unit with signals for crankshaft angles of 1° and 120°. The electronic control unit calculates the engine speed and crankshaft position based on these signals.
