The knock sensor is used to detect the knocking of the engine during combustion and to send Sensor the knock signal to the engine control computer as an important reference signal for correcting the ignition advance angle
Knock sensor refers to the combustion chamber of the natural mixture of spontaneous combustion caused by abnormal phenomenon, because the knock will produce high-intensity pressure wave impact combustion chamber, so not only can hear the sharp metal sound. But also on the engine parts have a greater impact. Ignition time is too early to produce the main reason for the knock. In order for the engine Temperature Sensor to operate at maximum power. It is best to advance the ignition time to the engine just does not occur the limits of the knock range, it must be added in the ignition system knock sensor. There are two kinds of knock sensors, one is magnetostrictive detonation sensor, the other is the piezoelectric knock sensor.
Common knock sensors are mainly piezoelectric, it is installed in the engine cylinder, this sensor using crystal or ceramic polycrystalline piezoelectric effect. But also the use of silicon doped piezoelectric resistance effect. The sensor housing is equipped with piezoelectric components / counterweight and wires. The principle is: when the engine cylinder block vibration occurs to the sensor shell, the shell and the counterweight between the relative movement. So that the piezoelectric element and the counterweight in the middle Speed Sensor of the squeeze changes, so that the output voltage signal changes, and control components can only detect the formation of 7KHZ vibration voltage. According to the size of the voltage to determine the knock strength. And accordingly the ignition time is delayed to avoid knocking.
Magnetostrictive detonation sensor shape and structure, the internal permanent magnet, by permanent magnet excitation of the magnetic core and the core around the coil. The working principle is that when the cylinder block of the engine vibrates, the sensor resonates with the engine at about 7 kHz, and the magnetic permeability of the core of the ferromagnetic material changes, so that the magnetic flux density of the permanent magnet through the core also changes, An induced electromotive force is generated in the winding around the core and the electrical signal is input to the ECU.
Knock sensor has non-resonant and resonant type of two, generally installed in the 2-cylinder and 3-cylinder, or 1,2 cylinder in the middle of a 3,4-cylinder in the middle one. The connection of the general knock sensor is wrapped with a shielded wire. When the knock sensor fails, the engine will be deflagration, ignition timing inaccurate, high fuel consumption, power down, the engine is rough, the engine there are many sensors, it is like our eyes, ears, nose, See, hear, smell, feel the information, all into electrical signals, passed to the car's computer system, so that the engine Throttle Position Sensor to make the right judgments, to assist the driver better driving the vehicle. With the progress and development of technology, the engine will be more and more sensors, more and more intelligent.