| 摘要 |
A pick-up provides a square wave signal whose period corresponds to 720 DEG /N where N is the number of engine cylinders for a four stroke, two cycle internal combustion engine. An integrator is reset by both positive-going and negative-going edges of said square wave signal to produce a sawtooth waveform having a period equal to 360 DEG /N. A blanking circuit which is coupled with the pick-up blanks the sawtooth waveform of said integrator during alternate half cycles of the square wave. The blanked sawtooth waveform is supplied to one input of a comparator and a desired timing signal to the other input of said comparator. The comparator provides an engine timing signal when a predetermined relationship between the blanked sawtooth signal and the desired timing signal is attained. In this way, the engine timing signal is given once per cycle of said blanked sawtooth waveform with the timing thereof relative to said square wave being determined by the desired timing signal. The preferred embodiment discloses a four cylinder engine configuration with electronic spark timing control. |
