GB1106923A - Spark ignition systems - Google Patents

Abstract

1,106,923. Ignition systems. JOSEPH LUCAS (INDUSTRIES) Ltd. March 3, 1966 [March 10, 1965], No. 10110/65. Heading F1B. A spark ignition system includes a semiconductor switch controlling the production of the required sparks and a pair of transformers providing signals to the control terminal of the switch for turning the switch on and off respectively. At the instant when a spark is required any convenient known means operated by the engine causes a negative signal to appear at the terminal 26. This signal turns the transistor 24 off and so the transistor 23 is turned on and current builds up in the winding 22. The e.m.f. in the winding 19 is blocked by the diode 17. When the transistor 23 is switched on the transistor 36 tends to switch off and the transistor 34 tends to switch on. The transistors 34, 36 act in conjunction with their associated components to cause a pulse to be applied to the winding 33 until the transistor 23 is turned off. Current is fed by the winding 31 to the switch 15 to turn it on. When the switch 15 is turned on the capacitor 42 discharges through the winding 43 to produce the required spark. While the switch 15 is on current builds up in the series circuit 13, 14, 15, 16 until when a predetermined current is reached the voltage across the resistor 16 turns the transistor 24 on. The transistors 34, 36 now revert to their original state so removing the forward drive to the switch 15 and the transistor 23 is turned off. The e.m.f. in the winding 19 provides a negative gate-cathode current to turn the switch off. The energy stored in the inductor 13 is now transferred to the capacitor 42 by way of the diode 48. The switch 15 may be a gate controlled switch or a transistor. In a modification the resistors 25, 27 are connected to the line 11 through an additional resistor and a Zener diode is added. The system may include resistors which render the operation of the system substantially independent of temperature variations.