Ignition coil apparatus for an internal combustion engine and production method thereof

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, 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;
• a permanent magnet arrangement which is 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;
• and
• an 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 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 magnet arrangement is arranged in all of the gaps, and
• wherein the gaps are provided inside the container.

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, wherein a container is formed by said partition, said base wall, and said outer wall;
• a primary coil which is provided in the container and arranged around and coaxially with the hole;
• 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;
• a core, which is provided in the container and which forms a magnetic circuit for magnetically coupling the primary and secondary coils by supplying electricity to the primary coil, wherein said core extends inside said primary coil along an axial direction of said primary coil, extends along remote axial ends of said primary coil and said secondary coil, and extends outside said secondary coil along an axial direction of said secondary coil such that said core substantially encircles said primary coil and said secondary coil, wherein the core 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, and 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;
• a permanent magnet provided in the gap;
• an insulating resin which is poured into spaces that are formed by storing the primary and secondary coils and the core in the container and is solidified to secure the primary and secondary coils and the core within the case;
• a synthetic resin molded part disposed between at least one of said second end surfaces and said permanent magnet for holding said permanent magnet in said gap.