Ac ignition system

Claim 1

For an internal combustion engine of the type including an ignition coil having a low voltage primary winding and a high voltage secondary winding, spark plugs connected to said secondary winding, a rotary cam adapted to operate ignition points, and a battery having a pair of terminals, one of said terminals being connected to ground, an improved AC ignition system comprising: a. a first set of ignition points insulated from ground and comprising a metal mounting plate, a fixed contact mounted on said plate and insulated therefrom, an insulated bushing mounted on said plate, a movable arm mounted on said bushing and carrying a second contact engageable with said fixed contact, spring means biasing said movable arm away from said fixed contact thereby biasing said points to open condition, actuating means mounted on said movable arm and co-operating with said cam for said cam to close said first set of points at times when a spark is required, and an insulated stop on said mounting plate to limit movement of said arm away from said fixed contact, b. a capacitance connected between said points and ground, c. an inverter for producing a substantially rectilinear AC voltage, said inverter comprising a vibrator, a transformer having a centre tapped primary winding and a secondary winding, said vibrator having a pair of fixed contacts and a contact movable between said fixed contacts, means connecting said movable contact to one terminal of said battery, means connecting each fixed contact to respective sides of said primary winding of said transformer, means connecting the centre tap of said primary winding of said transformer to the other terminal of said battery, and first circuit means connecting said secondary winding of said transformer through said first set of points to said primary winding of said ignition coil, (d) a second set of ignition points normally in closed condition and mounted to co-operate with said cam for said cam to open said second set of ignition points when a spark is required, d. second circuit means for connecting the primary winding of said ignition coil to said terminals of said battery through said second set of ignition points, f. and switch means normally interrupting said second circuit means thereby normally rendering said second set of points inoperative, said switch means including means operable to disconnect said inverter from said primary winding of said ignition coil and to close said second circuit means thereby rendering said second set of points operative and said first set of points inoperative.