There are three main types of crankshaft position sensors, namely, magnetoelectric induction type, Hall effect type and photoelectric type. The fault causes of crankshaft position sensors are different due to their types. ?
(1), magnetoelectric induction type
Advantages: simple structure, durability, high temperature resistance and low assembly requirements.
Disadvantages: the signal is easily disturbed, and ECU needs to design related signal processing circuits, which have low accuracy and are not suitable for VVT engines.
The fault of the magnetoelectric induction crankshaft position sensor is that the engine cannot be started. When checking the engine condition, it was found that the real reason why the engine could not be started was that the ignition was too late.
Solution: Reconnect the circuit, readjust the distributor and check the ignition timing.
(2) Hall effect formula
Advantages: the output is a high-precision digital signal.
Disadvantages: high assembly requirements, rotation sensitive installation, integrated electrical components, EMC requirements.
The Hall-effect crankshaft position sensor is used to control the sequential fuel injection, ignition timing and knocking of the engine, and the transmission signal is out of the normal range when there is a fault.
Solution: Check whether the permanent magnet, magnetic conduction plate and integrated circuit are normal.
(3), photoelectric type
The fault of photoelectric crankshaft sensor is that the engine does not accelerate well, it will automatically turn off when starting, and sometimes there will be high-voltage electric spark. The reason is that the ignition system is not working well, resulting in high pressure and weak fire.
Solution: Check the internal short circuit of low-voltage circuit, main relay, high-voltage ignition coil, engine control unit failure, and abnormal wear of some mechanical parts.
The above is the fault analysis of the crankshaft position sensor and the damage reason of the crankshaft position sensor.
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 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. Its signal disk and distributor shaft
Photoelectric type?
Rotating together, the outer ring of the signal disk has a 360-degree photoetching gap, generating a signal of crankshaft angle1; 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.
(Source: Baidu Encyclopedia: Crankshaft Position Sensor)