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Piezoelectric ceramic element for engine knocking sensor

Update time：2011-03-03 08:47　　　 Viewed：次

Knocking sensor is mainly used for vibration (knocking) caused by automobile engine’s abnormal combustion .The sensor converts this signal to electrical signals and transmits it to the microcomputer for engine control in order to meet the demands of automobile exhaust regulations, fuel improving and high output, etc. Provide material components of stable sensitivity characteristics even at high temperature.

Knocking sensor element is mainly using Japan Fuji ceramic pieces, which provide a guarantee to the trial function of the sensor, and Japan Fuji piezoelectric ceramic chip has 25 years of manufacturing excellence, which also ensures the proficiency of the piezoelectric ceramic in terms of its performance. The global market share of Fuji ceramic knocking sensor has reached 35%, which means that one in three cars is using Fuji piezoelectric ceramic chips.

There are commonly two kinds of knocking sensors : piezoelectric sensors and porcelain telescopic sensors. Among them, piezoelectric resonant sensor is most widely used and generally installed in the engine block, making use of piezoelectric effect to change mechanical vibration from detonation into signal voltage. When the frequency from detonation (about 6000 Hz) is consistent with the natural frequency of the piezoelectric effect sensor itself, resonance phenomenon would produce. The sensor outputs a high detonation signal voltage to ECU and ECU would correct ignition time to avoid the generation of detonation.

Knocking sensor is a kind of AC signal generator but they are very different from most other car AC signal generator. In addition to detecting rotors’ speed and position like magneto electric crankshaft and camshaft position sensor, they also detect vibration or mechanical stress. Different from the stator and the magnetic resistance, they are usually piezoelectric device. They can sense special materials of mechanical pressure or vibration (such as engine can produce AC voltage from detonation shock) .

Knocking sensor is installed in different locations of bodies or cylinders. When vibration or knocking occurs, it generates a small peak voltage. The greater the knocking or vibration is, the greater main production peak of the knocking sensor is. A certain amount of frequency reflect knocking or cylinder and knocking sensor is usually designed to measure frequencies that range from 5 to 15 K Hz . When the control unit receives these frequencies, computer would reset ignition timing to prevent continuous knocking. So knocking sensor is usually very durable and the sensors would only be damaged by the failure from itself.

Main kinds

For resonance type sensor

For non-resonant sensor

For cylinder with inner pressure sensors

Main specifications

Outer diameter: Ø 5 ~ 25 mm Ø

Inside diameter: 2 ~ Ø Ø 20 mm

Thickness: 0.2 ~ 5 mm

Recommend material: C - 202
(Editor：admin)

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