Knocking detection system for internal combustion engine

Claim 1

A system for detecting the degree of knocking of an internal combustion engine, the system comprising: a vibration sensing device which is attached to a body of an internal combustion engine and comprises a vibration pickup which has a housing and a seismic mass resiliently held in said housing and is capable of converting mechanical vibrations into electrical signals, and a resonance plate means fixed only in one end region thereof to said body of said engine for mechanically amplifying only those vibrations having a frequency within a band attributable to knocking of said engine, said housing of said vibration pickup being fixedly mounted on said resonance plate in a free end region distant from said one end region, said vibration sensing device, as an assembly of said pickup and said resonance plate, having a resonance frequency within a frequency band of vibrations attributable to knocking of said engine; reference signal producing means for producing an electrical reference signal which is variable depending on the rate of revolution of said engine; and signal treatment means for producing an electrical knock-indicating signal which represents the degree of knocking of said engine based on a comparison of an electrical vibration-indication signal derived from said vibration sensing device with said reference signal.

Claim 2

A system for detecting the degree of knocking of an internal combustion engine, the system comprising: a vibration sensing device which is attached to a body of an internal combustion engine and comprises a vibration pickup which has a housing and a seismic mass resiliently held in said housing and is capable of converting mechanical vibrations into electrical signals, and a resonance plate means fixed only in one end region thereof to said body of said engine for mechanically amplifying only those vibrations having a frequency within a band attributable to knocking of said engine, said housing of said vibration pickup being fixedly mounted on said resonance plate in a free end region distant from said one end region, said vibration sensing device, as an assembly of said pickup and said resonance plate, having a resonance frequency within a frequency band of vibrations attributable to knocking of said engine; reference signal producing means for producing an electrical reference signal which is variable depending on the rate of revolution of said engine; and signal treatment means for producing an electrical knock-indicating signal which represents the degree of knocking of said engine based on a comparison of an electrical vibration-indication signal derived from said vibration sensing device with said reference signal.

Claim 4

A system according to claims 1 wherein said signal treatment means comprise a peak detection means for intermittently detecting peak values of an electrical signal produced by said vibration sensing device and producing a peak-indicating signal representing each of the detected peak values, and a comparison means for comparing each peak value represented by said peak-indicating signal with said reference signal and producing a knock-indicating signal each time when the compared peak value is greater than a value represented by said reference signal at the moment of comparison.