Ignition coil for use in internal combustion engine

An individual ignition type ignition coil which is to be connected directly to a respective ignition plug of an internal combustion engine for use in the internal combustion engine comprising:

• a center core, a primary coil and a secondary coil installed concentrically in an interior portion of a coil case;
• insulation resin filled up among the center core, the primary coil and the secondary coil;
• and
• a bobbin on which at least said secondary coil is wound;
• wherein said bobbin is made of a thermoplastic resin member and has a surface with an uneven surface roughness which is rougher than a surface roughness of a skin layer and which, at its maximum, is more than 10 microns.

An individual ignition type ignition coil which is to be connected directly to a respective ignition plug of an internal combustion engine for use in the internal combustion engine comprising:

• a center core, a primary coil and a secondary coil installed concentrically in an interior portion of a coil case;
• insulation resin filled up among the center core, the primary coil and the secondary coil;
• and
• a bobbin on which at least said secondary coil is wound;
• wherein the bobbin is made of a thermoplastic resin member containing a suitable amount of a filler;
• wherein the filler has a diametrical thickness of 10-20 microns and a length of 50-200 microns;
• and
• wherein the filler projects from a bobbin surface of said bobbin in an amount which, at its maximum, is more than 10 microns.

An individual ignition type ignition coil which is to be connected directly to a respective ignition plug of an internal combustion engine for use in the internal combustion engine comprising:

• a center core, a secondary coil wound on a secondary bobbin, and a primary coil wound on a primary bobbin installed concentrically from an inner side of a coil case in order;
• insulation resin filled up among the center core, the primary coil and the secondary coil;
• wherein each of said primary bobbin and said secondary bobbin is made of a thermoplastic resin member containing a suitable amount of a filler;
• wherein said filler projects from at least an inner surface of said primary bobbin and an outer surface of said secondary bobbin in an amount which, at its maximum, is more than 10 microns;
• and
• wherein the insulation resin permeates clearance of the secondary coil so that said insulation resin is closely adhered to the inner and outer surfaces.

An individual ignition type ignition coil which is to be connected directly to a respective ignition plug of an internal combustion engine for use in the internal combustion engine comprising:

• a center core, a secondary coil wound on a secondary bobbin, and a primary coil wound on a primary bobbin installed concentrically from an inner side of a coil case in order;
• insulation resin filled up among the center core, the primary coil and the secondary coil;
• wherein said secondary bobbin is made of a thermoplastic resin member containing a suitable amount of a filler;
• wherein plural flanges for setting a respective spool area in which a dividing winding of said secondary coil is carried out are arranged, at intervals in an axial direction, at an outer surface of said secondary bobbin;
• wherein said filler projects from a surface of said bobbin including said outer surface of said secondary bobbin including said flanges in an amount which, at its maximum, is more than 10 microns;
• and
• wherein the insulation resin permeates clearance of the secondary coil so that said insulation resin is closely adhered to the filler projecting from the surface of said bobbin.

An individual ignition type ignition coil which is to be connected directly to a respective ignition plug of an internal combustion engine for use in the internal combustion engine comprising:

• a center core, a secondary coil wound on a secondary bobbin, and a primary coil wound on a primary bobbin installed concentrically from an inner side of a coil case in order;
• insulation resin filled up among the center core, the primary coil and the secondary coil;
• wherein said secondary bobbin includes a flange at an outer surface thereof to set a spool area in which winding of said secondary coil is carried out;
• wherein said flange at the outer surface of said secondary bobbin projects in an amount such that a distance between an outer diameter of said secondary coil and an outer diameter of said flange of said secondary bobbin is at least as great as a maximum diameter of said secondary coil;
• wherein said secondary bobbin is made of a thermoplastic resin member containing a suitable amount of a filler;
• wherein said filler projects from at least part of the outer surface of said secondary bobbin including said flange in an amount which, at its maximum, is more than 10 microns;
• and
• wherein the insulation resin permeates clearance of the secondary coil so that said insulation resin is closely adhered to the exposed filler.

An individual ignition type ignition coil which is to be connected directly to a respective ignition plug of an internal combustion engine for use in the internal combustion engine comprising:

• a center core, a secondary coil wound on a secondary bobbin, and a primary coil wound on a primary bobbin installed concentrically from an inner side of a coil case in order;
• insulation resin filled up among the center core, the primary coil and the secondary coil;
• wherein said secondary bobbin is made of a synthetic resin;
• wherein plural flanges for setting a respective spool area in which a dividing winding of said secondary coil is carried out are arranged, at intervals in an axial direction, at an outer surface of said secondary bobbin;
• and
• wherein said flanges at the outer surface of said secondary bobbin project in an amount such that a distance between an outer diameter of said secondary coil and an outer diameter of said flange of said secondary bobbin is more than a maximum diameter of said secondary coil.