초록 ▼

An analog signal processing circuit for detecting engine knock is disclosed. A sensor mechanically resonant at characteristic engine knock frequencies provides an analog signal related to engine knock and engine background noise. An envelope detector provides the signal envelope of the sensor signal

An analog signal processing circuit for detecting engine knock is disclosed. A sensor mechanically resonant at characteristic engine knock frequencies provides an analog signal related to engine knock and engine background noise. An envelope detector provides the signal envelope of the sensor signal. An integrator means provides an average signal related to the average of the envelope signal while an attenuator and subsequent filter (integrator) provide an integrated and attenuated signal which responds faster to amplitude changes in the envelope signal than the average signal. The integrated and attenuated signal level is set below the average signal level for conditions of no-knock. A comparator receives both the average signal and the integrated and attenuated signal and provides an output signal indicating knock detection in response to the amplitude of the integrated and attenuated signal exceeding the amplitude of the average signal. Preferably the knock detection output of the comparator is latched and the comparator is reset by periodic engine pulses.

대표청구항 ▼

An analog engine knock signal processing circuit comprising: engine knock sensor means for providing an analog engine knock signal representative of engine knock and engine background noise; detector means, including a rectifier means, coupled to said knock sensor means for receiving and rectifying

An analog engine knock signal processing circuit comprising: engine knock sensor means for providing an analog engine knock signal representative of engine knock and engine background noise; detector means, including a rectifier means, coupled to said knock sensor means for receiving and rectifying said knock signal and developing an envelope output signal, at an envelope terminal, representative of the peak magnitude signal envelope of the knock signal; integrator means coupled to said envelope terminal for receiving and integrating said envelope signal and providing an average signal related to the average magnitude of said envelope signal, said average signal being provided at an average terminal, the amplitude of said average signal having a first response time in response to amplitude changes in said envelope signal, attenuator means coupled to said envelope terminal for receiving said envelope signal and providing an amplitude attenuated signal related to a predetermined amplitude attenuation of said envelope signal, the amplitude of said attenuated signal responding to changes in the magnitude of said envelope signal faster than the amplitude of said average signal, said attenuator means including circuitry for adjusting the amplitude of said attenuated signal to less than the amplitude of said average signal for constant amplitudes of said envelope signal; and comparator means coupled to both said integrator means and said attenuator means for receiving both said average signal and said attenuated signal and providing a knock detection output signal at an output terminal in response to the amplitude of a faster responding signal derived from said attenuated signal exceeding the amplitude of said average signal, whereby by adjusting the amount of attenuation of said attenuator means, desired knock detection characteristics of the signal processing circuit for varying amplitudes of engine background noise can be readily obtained and by using the envelope signal some immunity from falsely detecting short duration engine noise spikes as engine knock is obtained.