Ignition system for an internal combustion engine using thyristors

Claim 1

An ignition system for an internal combustion engine, including: a low-voltage direct-current supply, at least one spark plug, an ignition coil with a primary winding and a secondary winding for connection to the supply and to the at least one plug, respectively, at least one first electronic switch between the primary winding of the coil and the supply for controlling the flow of current in the primary winding, an inductor between the supply and the primary winding of the coil, a capacitor in parallel with the circuit branch including the primary winding and the first electronic switch, a second electronic switch between the inductor and the supply and adapted to disconnect the circuit downstream of the inductor from the supply in its closed condition, and an electronic control unit arranged to control the first and second electronic switches in a predetermined manner, wherein the at least one first electronic switch is constituted by a thyristor and, in order to cut off the flow of current in the thyristor, the electronic control and operating unit is adapted to close the second electronic switch so as to disconnect the said circuit branch from the supply, and then to reopen the second switch after a time sufficient to allow the current flowing in the thyristor to fall below a predetermined value.