Electronic IC ignition system - uses pressure and position transducers with controllable timing circuit to obtain peak pressure just after TDC

摘要

The electronic ignition system uses cylinder pressure and crankshaft position transducers to time the ignition so the peak pressure occurs just after top dead centre. The pressure transducer signal (E1) drives a transistor (T1) into saturation near its peak value and clamping and differentiating circuits (D2,T2) produce a square pulse from this. The position detector signal (E2) clamps an oscillator (T8) to give pulse bursts which are converted to a rectangular pulse train after rectification and clamping (D5,T9). The phase difference between these two signals is detected and a DC voltage proportional to the difference produced. A binistor (T6) with a ramp generator formed by an RC circuit at one terminal and its threshold inversely set by the DC level is released by a negative edge of the pulse train from the position detector to commence timing. When the threshold is reached a firing pulse is generated. Under starting where no pressure data has been received the DC level is zero and the pressure transducer pulse is used to generate the ignition pulse.