Toyo Denso Kabushiki Kaisha

Toyo Denso Kabushiki Kasiha

Yoshiharu Saito

Makoto Sakamaki

Toshiyuki Shinozawa

An engine igniting coil device adapted to be mounted in a cylindrical bore of an engine and directly connected with an ignition plug therein has a coil case containing an igniting coil assembly and made of conductive magnetic material which is held at the ground potential level, thus preventing a decrease of output factor of the igniting coil of produced magnetic flux when spreading about and passing through a cylinder head of the engine and eliminating the possibility of leakage discharge from a high-voltage portion of the igniting coil assembly to the coil case and the cylinder head.

Engine igniting coil device

An engine igniting coil device directly attachable to an igniting plug, wherein both primary and secondary coil bobbins have flangeless ends, the secondary coil bobbin has inwardly protruding ribs for coaxially supporting the flangeless end of the primary coil bobbin mounted therein and the secondary coil bobbin also has protrusions formed at its external wall apart from a high-voltage terminal of the secondary coil wound thereon and is coaxially mounted in a coil case by abutting its protrusions on an inner wall thereof, thus eliminating the possibility of damaging the bobbins by a large thermal stress produced in solidified insulating resin in a coil case by a differential thermal shrinkage in an axial direction and preventing a leakage current from a high-voltage side of the secondary coil bobbin to the coil case through a flange-like connection.

In an engine igniting coil device comprising an ignition coil assembly potted integrally in a coil case by injecting melted insulating resin, a secondary coil is formed on a coil bobbin by bank winding an element wire in layers of wire turns one over another at a certain bank angle in an axial direction on the bobbin and by slope-winding of layers on the end portion of the bobbin by tapering the coil (by reducing the number of layers therein) in the winding direction. This allows setting a dielectric strength of interlayer insulation of the secondary coil according to a potential distribution therebetween, which is secured by forming an insulation resin layer of a reduced thickness between the coil case and the secondary coil of the secondary coil bobbin, thus realizing a compact engine-igniting coil device.

Growing community of inventors

Tsurugashima, Japan

Yoshiharu Saito