GB938948A - Internal combustion engine ignition systems - Google Patents

Abstract

938,948. Ignition systems. GENERAL MOTORS CORPORATION. March 8, 1962 [March 13, 1961], No. 8933/62. Class 7(4). In an internal-combustion engine ignition system a spark plug is adapted to be energized from a voltage source by an energizing circuit controlled by a first semiconductor switch device which forms part of a charging circuit for a capacitor, a second semi - conductor switch device is operable to connect the first switch device across the capacitor when the second switch device is conductive and a device operating in time with the engine is arranged to vary the conductivity of the second switch device. When the transistor 58 is conductive between collector and emitter there will be a base circuit for transistor 46 by way of resistor 60 and with flow of base current in the transistor 46 the latter will be fully conductive between emitter and collector so that the junction 44 will be changed from earth potential to the positive potential of the battery 88 and accordingly a discharge path for the capacitor 40 is established by way of the emitter to collector circuit of transistor 46. The capacitor discharges by way of a circuit including resistor 38 battery 88 lead wire 34 and the emitter collector circuit of the transistor 46. The voltage appearing across the capacitor 40 will be impressed across the emitter and base of the transistor 32 and the polarity of the voltage on the capacitor 40 is such that the base of the transistor 32 suddenly becomes positive with respect to its emitter thereby rendering the transistor 32 non-conductive between emitter and collector and cutting off current flow to the primary winding 26. The sudden interruption of the current flow through the primary winding 26 causes a large voltage to be induced in the secondary winding 22 and this voltage is applied to a spark plug 12 by way of the distributer 14.