1. Classification of the knock sensor
There are also various types of knock sensor. Common are piezoelectric ceramic and telescopic types. Wherein the piezoelectric resonator sensors most applications, it is generally installed in an upper portion of the engine block using mechanical vibration generated by the piezoelectric effect when the detonation into a voltage signal. When the vibration frequency is consistent (about 6000Hz) when the knock sensor itself and the piezoelectric effect natural frequency, i.e., resonance phenomenon. At this time the sensor outputs a high voltage signal to the knock ECU, ECU timely correction ignition timing to avoid knocking.
knock sensor signal generator is AC, but they are most other automotive AC generator very different, except as magnetic crankshaft and cam shaft position sensor as the probe shaft speed and position, they detect vibration or mechanical stress. The stator and the magnetoresistors different, they are usually a piezoelectric device. They can sense vibrations or mechanical stress (e.g. to produce an AC voltage when starting the engine knock) of special material.
The knock sensor placed in different positions of the engine block or cylinder. When vibration or knocking occurs, it generates a small voltage peak, the larger the vibration or knock. The main peak of the knock sensor producing greater. Indicates that certain frequency is high or knock knocking, knock sensor typically designed to 5 to 15 kHz frequency range measured. When the control unit receives these frequencies, the computer re-correcting the ignition timing to prevent knocking continues, a knock sensor is generally very durable. Therefore, the sensor will be damaged because of their failure.
the pressure wave generated when an engine knock, a frequency of 1-10 KHz. Cylinder pressure wave to pass, so that the metal particle vibration acceleration. Knock sensor is an accelerometer by measuring acceleration of the vibration of the cylinder surface detecting a knock intensity of the pressure. is a major cause of premature ignition timing knocking Since the maximum power requirements of the engine can be issued, in order not to have a loss of engine power but no detonation, detonation transfer installationSensor, electronic control means for automatically adjusting the electrical ignition timing.