Ignition coil assembly for internal combustion engines

Claim 1

An ignition coil assembly for an internal combustion engine having a plurality of coil units each of which includes a primary coil supplied with a primary current from a battery and a secondary coil magnetically coupled with the primary coil, both ends of which are connected to respective spark plugs, center cores around which the respective coil units are provided, a side core magnetically linked with the center cores to form closed magnetic paths for the magnetic fluxes produced by the respective primary coils, and switching means for controlling the primary currents supplied for the respective primary coils in response to ignition signals furnished by an ignition control unit, characterized in that each of said center cores is a laminated core formed of grain oriented silicon steel plates and so placed within a coil unit that an axis of easy magnetization of the center core coincides with the direction of the magnetic flux produced by the primary coil of the coil unit, that said side core is a laminated core made of non-grain oriented silicon steel plates as one body and linked magnetically with each of said center cores with an air gap in a part of the magnetic path formed by each of said center cores and said side core, and that each of said primary coils, when it is supplied with a primary current, produces the magnetic flux which is in the same direction in the center core as those produced by any other primary coils.