Tuesday, May 24, 2011

Sensors - Knock sensor

Knock Sensor
The knock sensor is sense the knock from the engine, create its own voltage and sent it to ECU.
Connect the knock sensor up to an oscilloscope, tap the end of the sensor and observe the waveform:

Explain why we are reading a voltage from the sensor when we are not supplying a voltage to it:
The knock sensor uses crystals or polycrystalline ceramic piezoelectric effect. When the engine cylinder block vibration, the piezoelectric elements inside the sensor press together and create voltage.

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