Marelli Autronica

Michele Scarnera

An ignition system for an internal combustion engine comprises a 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, a first electronic switch between the primary winding and the supply, 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 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 unit which controls the first and second switches in a predetermined manner. The first switch is constituted by a thyristor and, when the current flowing in the thyristor is to be cut off, the electronic control unit closes the second electronic switch and then reopens it after a time sufficient to allow the current flowing in the thyristor to fall below a predetermined value.

Ignition system for an internal combustion engine using thyristors

In a first operative mode, the control unit first causes energy to be stored by the inductor and then connects the inductor to the capacitor so as to form a resonance circuit whose energy is discharged into the primary winding of the coil in order to generate a spark. In a second operative mode, the unit causes a plurality of cycles to be effected to charge the capacitor so as to increase the voltage across its terminals at each cycle and the capacitor is then discharged into the primary winding of the ignition coil in order to generate the spark.

Growing community of inventors

Turin, Italy

Michele Scarnera