Detection of Higher Frequency Vibration to improve Knock Controllability

For a Knock Control System (KCS) with a vibration sensor mounted on the engine block, means of improving the ratio of knock signal to engine vibration noise are discussed. From analyses of cylinder pressure and engine block vibration spectrums, it is shown that noise is lower in the second knock resonance frequency.

The development of a resonance type knock sensor detecting this higher frequency is described. A new KCS utilizing this sensor is evaluated and found to improve knock controllability, especially in engines with a high compression ratio or supercharging.