What is the function of a knock sensor?

[Jonathan]

The functions of a knock sensor are: 1. To measure engine vibration and adjust the ignition timing when engine knocking occurs; 2. It serves as an AC signal generator to detect the speed and position of the crankshaft. The knock sensor consists of: a magnetic core, permanent magnet, and induction coil. The working principle of the knock sensor is: when vibration or knocking occurs, it generates a small voltage peak. The more severe the knocking or vibration, the higher the voltage peak produced by the knock sensor. A certain high frequency indicates knocking or vibration. Knock sensors are typically designed to measure frequencies in the range of 5 to 15 kHz. When the control unit receives these frequencies, the computer readjusts the ignition timing to prevent further knocking.