Ignition circuit having a high-energy spark for an internal combustion engine

摘要

An ignition circuit is for an internal combustion engine in a handheld portable work apparatus. A combustion chamber ( 4 ) is configured in the cylinder ( 3 ) of the engine ( 1 ) which is delimited by a piston ( 5 ) driving a crankshaft ( 7 ). An electromagnetic induction loop ( 13 ) and a pole wheel ( 10 ) are provided. The pole wheel ( 10 ) revolves with the crankshaft ( 7 ) and is assigned to the induction loop ( 13 ). The pole wheel ( 10 ) periodically changes the magnetic flux in the induction loop ( 13 ). An ignition capacitor ( 16 ) is charged by a charge coil ( 14 ) of the induction loop ( 13 ) and is discharged via a discharge circuit ( 15 ) via an ignition coil ( 17 ). The ignition coil ( 17 ) is connected to a spark plug ( 19 ) projecting into the combustion chamber ( 4 ). For achieving a powerful ignition spark, the discharge of the ignition capacitor ( 16 ) is prevented by an rpm evaluation circuit ( 23 ) when the rpm curve ( 30 ) exhibits an rpm change (Deltan) which exceeds a pregiven threshold value.