Capacitor discharge ignition system having a charging control means

Abstract

The invention provides charging control circuitry (20) for a capacitor discharge ignition system (10) having power capacitors (21) connected to be discharged by main electronic switches such as SCR's (23) into ignition transformers (24) to sequentially fire the engine's spark plugs (16). The charging control circuits (20) each include a charging SCR (26) to limit charging current flow to the main capacitor (21), unless a discharge pulse into the ignition transformer (24) has occurred in the recent past. Thus if a short circuit in either the main capacitor (21) or main SCR (23) in one of the ignition circuits (19) prevents that ignition circuit from properly functioning, the charging SCR (26) will limit the flow of charging current to the defective circuit and allow the other ignition circuit (19) to receive charging current. The gate of the charging SCR (26) is controlled by an amplified signal from a memory capacitor (28) which is charged by the discharge pulse from the corresponding ignition circuit (19). The same memory capacitor (28) also provides power to drive an indicator such as a light emitting diode (40).