Patent ID: 6211763
Filing Date: 2001-04-03
Classification: H01F

Abstract:
An ignition coil apparatus for an internal combustion engine comprising:a synthetic resin case having a cylindrically shaped partition that forms a hole for passing therethrough a shaft rotating in synchronization with the rotation of the internal combustion engine, a base wall that has an annular shape and that is disposed adjacent to said partition and extends radially outward from said hole, and a cylindrical outer wall that is disposed adjacent to an outer periphery of said base wall and faces said partition, wherein a container is formed by said partition, said base wall, and said outer wall;a primary coil which is stored in the container and arranged around and coaxially with the hole, wherein the primary coil has a substantially cylindrical shape;a secondary coil that is disposed in said container and is arranged coaxially with said hole such that said secondary coil is placed between said primary coil and said outer wall, wherein said secondary coil has a substantially cylindrical shape;cores, which are stored in the container around the hole at equal intervals in a circumferential direction of the primary and secondary coils and which form a plurality of magnetic circuits for magnetically coupling the primary and secondary coils by supplying electricity to the primary coil, wherein said cores extend inside said primary coil along an axial direction of said primary coil, extend along remote axial ends of said primary coil and said secondary coil, and extend outside said secondary coil along an axial direction of said secondary coil such that said cores substantially encircle said primary coil and said secondary coil;permanent magnets which are respectively arranged in all of the magnetic circuits formed by the plurality of cores to provide the cores with a magnetic flux opposite in direction to the magnetic flux of the magnetic circuits; andan insulating resin which is poured into spaces that are formed by storing the primary and secondary coils and the plurality of cores in the container and is solidified to secure at least the primary and secondary coils and the plurality of cores within the case;wherein each of the plurality of cores comprises a pair of cut cores and one of first end surfaces and second end surfaces of said cut cores are placed between said partition and an inner circumference of said primary coil and another of said first end surfaces and second end surfaces of said cut cores are placed between said outer wall and an outer circumference of said secondary coil,wherein said first end surfaces of the pair of cut cores are placed in contact with each other,wherein said second end surfaces of the pair of cut cores are spaced apart from each other to form a gap having a predetermined distance therebetween,wherein said permanent magnets are respectively arranged in all of the gaps, andwherein the gaps are provided inside the container.