What is the working principle of the car speed sensor?

Just as there are different types of car sensors, car speed sensors also have different kinds of functions. The principle of different car speed sensors is definitely different. The following ones are introduced for you.

(1) The magnetoelectric vehicle speed sensor simulates an AC signal generator to generate an alternating current signal, usually consisting of a magnetic core with two terminals and a coil. The gears on the magnetic wheel will produce a one-to-one series of pulses, the shape of which is the same. The amplitude of the output signal is proportional to the rotational speed of the magnetic group wheel (vehicle speed), and the frequency of the signal is expressed in the rotational speed of the magnetic group wheel. The engine control computer or ignition module relies on this sync pulse signal to determine the trigger spark time or fuel injection timing.

(2) Hall-type vehicle speed sensors They are mainly used in crank angle and camshaft position for switching ignition and fuel injection circuit triggering. They are also used in other position control and control circuit circuits that need to control rotating parts. Consisting of an almost completely closed magnetic circuit comprising a permanent magnet and a magnetic pole portion, a soft magnet blade rotor passes through the air gap between the magnet and the magnetic pole, and a window on the vane rotor allows the magnetic field to pass unimpeded and reaches Hall The effect sensor, while the portion without the window interrupts the magnetic field.

(3) Photoelectric speed sensor consists of a two-photoconductor fiber with a perforated turntable, a light-emitting diode, and a phototransistor as a light sensor. A phototransistor-based amplifier provides sufficient power for the engine control computer or ignition module, and the phototransistor and amplifier produce a digital output signal (switching pulse). The light-emitting diode transmits light to the photodiode through the hole in the turntable to realize light transmission and reception.

(4) Engine Speed ​​Sensor - Detects the engine speed, which is usually achieved by using the crankshaft position sensor to detect the engine speed and output. Used for fuel injection quantity, ignition advance angle, power transmission control, etc.

(5) Vehicle speed sensor - usually obtained by directly or indirectly detecting the speed of the car tire, mainly reflected in the fact that we can know the speed of our own form when the car is driving.

(6) Wheel speed sensor—detects the wheel speed and outputs the test result to the ECU. The main function is to control the vehicle brake and drive control.

(7) Deceleration sensor - The main purpose is to detect the deceleration speed of the car when decelerating, and also to pass this signal back to the ECU, the control and drive control of the car brake.