The structure and working principle of the knock sensor

Knock sensor is an important component of engine electronic control system, its function is to detect whether the engine detonation, and the signal sent to ECU engine. Knock sensor common has two kinds, one is the magnetostrictive knock sensor, a piezoelectric type knock sensor. Magnetostriction type knock Engine Water Temperature Sensor in which a permanent magnet, permanent magnet excitation by around the magnetic core and the iron core coil. Its working principle is: when the engine cylinder block vibration,Car Temperature Sensoris about 7kHz and the engine to produce resonance, strong magnetic material core permeability changes, resulting in a permanent magnet flux density through the core also change, so as to generate the induced electromotive force in winding around the core, and the electrical signal input ECU. Piezoelectric type knock sensor using the effect of piezoelectric crystal or ceramic polycrystals and work, but also the use of piezo resistance effect of the doped silicon. The sensor housing is provided with a piezoelectric element, counterweight block and wire etc.. Its working principle is: when the engine cylinder block vibration and vibration transmitted to the casing of the sensor, relative movement between the shell and the counterweight, variation of piezoelectric element is clamped in between the pressure occurs, resulting in voltage. ECU detects the voltage, and according to the size of its value judgment of knock intensity.