Knock Sensor-piezoelectric ceramic sensor

Knock sensor installed in the middle of the engine cylinder to four-cylinder machine as an example installed in the 2-cylinder and 3-cylinder, or 1, 2 cylinder in the middle of a 3,4-cylinder middle one. Its role is used to determine the engine jitter, when the engine is used to adjust the ignition when the advance angle.

Piezoelectric sensor is generally installed in the upper part of the engine body, the use of piezoelectric effect to knock the mechanical vibration generated when the signal voltage. When the vibration frequency (about 6000 Hz) when the knock is generated coincides with the natural frequency of the piezoelectric effect sensor itself, resonance occurs. At this time the sensor will output a very high knock signal voltage sent to the ECU, ECU timely correction of ignition time, to avoid the occurrence of knock.

The effect of the knock sensor is to transmit the engine knock in the form of an electrical signal to the electronic control module as an important basis for the control module to adjust the ignition timing to prevent further knocking. The knock sensors are generally of the piezoelectric ceramic type, and when the engine has jitter, the ceramic inside is squeezed to produce an electrical signal.