Magneto ignition system for an internal combustion engine

Claim 1

Magneto ignition system for an internal combustion engine having a spark gap, said system including an ignition coil system having a primary winding (15); two terminals (A, B) on the primary winding; a secondary winding (16); an armature core (14, 14a) and a rotating magnet (12) coupled to rotate with the engine; an electronic switch (21) connected to interrupt current flow through the primary winding at an ignition instant; an electronic control circuit (29) coupled to the primary winding and connected to control conduction or blocking of the electronic switch (21) and having a control switch (27); a first R/C series timing circuit (30, 31) connected to said control switch (27) and across the primary winding, a Zener diode serially connected in said first R/C series circuit, and a second series R/C circuit (34, 33) to modify the conduction characteristic of the first timing circuit and provide a change of timing instant as a function of frequency of voltages induced in the primary winding, and hence provide for speed-dependent ignition advance, said timing circuits controlling said control switch (27); and comprising, in accordance with the invention, means for insuring operation of the engine in a predetermined direction only including a diode (35) connected in parallel to the second timing circuit (34, 33), the diode (35) being poled in a direction opposite to the polarization of the Zener diode (32); and wherein the second timing circuit (34, 33) has one of its terminals connected to that one of terminals (A) of the primary winding (15) which, at the ignition instant, has a voltage which is high with respect to the other terminal (B) thereof.