What is the Function of a Knock Sensor?

[EmeryLee]

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 rotating shaft. A knock sensor consists of: a magnetic core, permanent magnet, and induction coil. The working principle of a knock sensor is: when vibration or knocking occurs, it generates a voltage peak. The greater the knocking or vibration, the higher the peak voltage produced by the knock sensor. A certain high frequency indicates knocking or vibration. The knock sensor can measure frequencies in the range of 5 to 15 kHz. When the control unit receives these frequencies, the computer recalibrates the ignition timing to prevent further knocking.