Wheel speed sensors are generally installed on the hub of each wheel and the position of the front wheel brake disc, but this is not necessarily the case for some imported cars.
In some rear-wheel drive cars, the main reducer or transmission has only one electromagnetic induction speed sensor. The sensor is installed on the main reducer housing or transmission housing, and the gear ring is installed on the main reducer input shaft or transmission output shaft. It provides signals to the anti-lock braking system to control the braking force. Installation position of front wheel speed sensor
Rear wheel speed sensor installation position Wheel speed sensor type
Magnetoelectric wheel speed sensor;
Magnetoelectric wheel speed sensor structure: mainly composed of permanent magnet, polar axis and induction coil, divided into chisel, column and diamond.
Its advantages are simple manufacturing cost, simple manufacturing structure and no fear of oil sludge. His disadvantage is that the frequency response is not very high. When the vehicle is driving at high speed, the response frequency will not keep up, resulting in signal error. The anti-electromagnetic interference ability is very poor, and the output signal amplitude is relatively small. Principle of magnetoelectric wheel speed sensor: it is mainly composed of permanent magnet iron core and coil. The magnetic field lines mainly come out through one pole of the magnetic core, pass through the gear ring and air body, and then return to the other pole. Whenever the wheel is running, the reluctance will be changed by the induced magnetic field in turn, which will lead to the corresponding change of potential. Each frequency and amplitude reflects the speed at which the wheel rotates.
Hall wheel speed sensor:
Hall wheel speed sensor consists of two parts: sensing head and gear ring. The sensor head also includes a permanent magnet, a Hall element and an electronic circuit.
This kind of sensor is mainly made by using the principle of Hall effect. Its advantages are that the voltage amplitude of the output signal is not affected by the rotating speed, the frequency response is high, and the electromagnetic interference resistance is strong.
Principle of Hall wheel speed sensor: The current is mainly controlled by both ends of the semiconductor. When the magnetic field is applied vertically to the chip, the chip will generate a potential to control the current and magnetic induction at both ends. The output of the signal mainly depends on the magnetic induction intensity, and the Hall potential pulse is generated by the change of the input intensity. It is mainly to amplify, shape and amplify the inside of the wheel, and reflect the speed of the wheel through the pulse frequency.
Function of wheel speed sensor
The wheel speed sensor is mainly used to test the speed of automobile wheels.
The wheel speed sensor detects the frequency signal (in fact, it can also be said to be the speed signal) of each wheel rotation, and then transmits this signal to the ABS computer. When the vehicle speed reaches 40KM/h (in fact, the wheel speed frequency detected by the wheel speed sensor is also 40KM/h), you suddenly brake and the ABS system starts to work. When the ABS computer controls the wheel braking release, the wheel speed sensor transmits the rotation distance signal of the tire from braking to rotation to the ABS computer, so that ABS controls the braking and achieves the optimal braking distance. Wheel speed sensor has become an indispensable sensor for modern cars. Vehicle dynamic control system (VDC), vehicle electronic stability program (ES P), anti-lock braking system and automatic transmission control system all need speed information.
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