Patent ID: 7363910
Filing Date: 2008-04-29
Classification: F02D,F02P

Abstract:
1. An ignition circuit for a two-stroke internal combustion engine, the engine including a cylinder, a piston disposed in said cylinder to move upwardly and downwardly therein during operation of said engine, a combustion chamber formed in said cylinder and delimited by said piston, a crankcase connected to said cylinder and a crankshaft supported in said crankcase driven in rotation by said piston, the ignition circuit comprising: an electromagnetic induction loop conducting magnetic flux and including a charging coil in which voltage is induced; a pole wheel operatively connected to said induction loop and revolving with said crankshaft to periodically charge said magnetic flux in said induction loop in dependence upon the position of said crankshaft; an electronic control circuit including a capacitor connected to said charging coil to be charged by the voltage induced in said charging coil; a spark plug mounted in said cylinder so as to project into said combustion chamber; an ignition coil connected to said spark plug to ignite a mixture present in said combustion chamber; said electronic control circuit further including a discharge circuit for discharging said capacitor via said ignition coil at predetermined positions of said crankshaft; an rpm evaluation circuit for monitoring said discharge circuit and intervening therein to perform an override function when an rpm change (Δn) in the rpm curve deviates from a pregiven threshold value; and, said rpm evaluation circuit inhibiting said discharge circuit for a next crankshaft revolution when said threshold value is exceeded in order to suppress a discharge of said capacitor and an ignition (Z).