Ignition system for an internal combustion engine

Claim 1

An ignition system for an internal combustion engine comprising an ignition coil having a primary winding and a secondary winding, a capacitor, a charge power source for supplying charge current of said capacitor, a thyristor for discharging said capacitor through said primary winding, and a magneto AC generator having a signal generating winding connected through a diode across the gate and cathode of said thyristor, characterized in that said generator has a rotor including a substantially cup-shaped flywheel with a plurality of permanent magnets arranged about the inner periphery of said flywheel so as to produce a substantially alternating magnetic field about the circumference except at a part thereof where the magnetic field is unchanged, and a substantially U-shaped stator core on which said signal generating winding is wrapped, said U-shaped stator core having a pole to pole distance corresponding to the circumferential length of said part where the magnetic field in unchanged, whereby at least two successive local maximum points to appear in the rate of change of the magnetic flux interlinked with said signal generating winding, so that the waveform of the voltage induced in said signal generating winding has at least two successive peaks of the same polarity.