Automotive Sensor classification

- Mar 15, 2019-

1. Magnetically Electric speed sensor 

The Magnetoelectric speed sensor is an analog AC signal generator that produces alternating current signals, usually consisting of a core and coil with two terminal. The two coil terminal is the terminal of the sensor output, and when the annular wing wheel made of iron (sometimes called a magnetic group wheel) rotates through the sensor, an AC voltage signal is generated in the coil. The one-by-one gear on the magnetic group wheel will produce one by one corresponding series pulses, the shape of which is the same. The amplitude of the output signal (peak to peak voltage) is proportional to the speed of the magnetic Group Wheel (speed), and the frequency of the signal is reflected in the speed size of the magnetic group wheel. The air gap size between the sensor core and the magnetic group wheel has a great influence on the amplitude of the input signal of the sensor, and if one or more teeth are removed on the magnetic group wheel, a synchronous pulse can be generated to determine the position of the upper stop point.

This causes a change in the frequency of the output signal, and the amplitude of the output signal changes when the tooth decreases, and it is by this synchronous pulse signal that the engine control computer or ignition module determines the time of the trigger fire or the moment of fuel injection.

2. Hall Speed Sensor Hall effect 

Sensors (switches) are very special in automotive applications, mainly due to the conflict of space around the transmission, Hall effect sensors are solid sensors, which are mainly used in crankshaft corners and camshaft positions, for switching ignition and fuel injection circuit trigger, It is also used in other computer circuits that need to control the position and speed of the rotating parts. A Hall effect sensor or switch, consisting of an almost completely closed magnetic path containing a permanent magnet and a magnetic pole part, a soft magnet blade rotor passing through the air gap between the magnet and the magnetic pole, and the window on the blade rotor allows the magnetic field to pass through and reach the Hall effect sensor, while the part without the window interrupts the magnetic field and, therefore,

The role of the blade rotor window is to switch the magnetic field so that the Hall effect is turned on or off like a switch, which is why some automakers refer to Hall effect sensors and other similar electronic devices as Hall switches, which are actually a switchgear, and its key functional component is the Hall effect sensor.

3. Photoelectric Speed sensor 

The photoelectric speed sensor is a solid photoelectric semiconductor sensor, which consists of two optical conductor fibers with holes in the turntable, a light-emitting diode, and a photoelectric transistor as a light sensor. An amplifier based on photoelectric transistor provides a signal of sufficient power to the engine control computer or ignition module, and the photoelectric transistor and amplifier generate a digital output signal (switch pulse). Light emitting diodes pass through the shone on the turntable to the photodiode to achieve the transmission and reception. The discontinuous holes in the turntable can be opened and closed to the light source on the photoelectric transistor, which in turn triggers the photoelectric transistor and amplifier to turn the output signal on or off like a switch. The method of observing the output waveform of the photoelectric speed sensor from the oscilloscope is exactly the same as the Hall speed sensor, except that the photoelectric sensor has a weakness that they are sensitive to the interference of oil or booty in light passing through the turntable, so the functional elements of the photoelectric sensor are usually designed to be well sealed and

However, damaged sub-appliances or gasket containers in use will cause oil or stolen goods into sensitive areas, which can cause driving performance problems and generate fault codes.