Combustion timing method and apparatus with direct TDC detection

摘要

Method and apparatus for timing combustion events in the combustion chamber of an internal combustion engine wherein a piezoelectric transducer is utilized to develop a signal corresponding to the first derivative of pressure within the cylinder being monitored. A signal processing circuit detects that change in polarity of the first derivative signal which occurs at the transition between compression and expansion of cylinder volume during the combustion cycle of the piston. Circuitry is provided for effectively disregarding all other polarity changes or "zero crossings" of the transducer output signal which are not related to the achievement of the top dead center position by the piston within the cylinder. This directly derived indication of a transition from compression to expansion in the combustion chamber is combined with other timing signals for the monitoring or controlling of injection or ignition timing for the engine.