Engine ignition coil device

An open-magnetic-circuit type engine ignition coil device comprising:

• a coil case composed of a first cylindrical case and a second cylindrical case having a small tubular hole in its center portion and an upper external shoulder at its open end fitted into an open end of the first case to form a closed end of the coil case;
• and an internal assembly consisting of a primary coil bobbin, a secondary coil bobbin with a projecting high-voltage terminal holder formed at a center of an end flange portion of the secondary coil bobbin, a rod-shaped core, and a high-voltage terminal attached to the high-voltage terminal holder and having a contact for electrically connecting an ignition plug thereto, characterized in that the coil case and the internal assembly mounted therein with the high-voltage terminal holder press-fitted in the small tubular hole of the secondary case with a tip of the contact projected outwardly therefrom are integrally formed with each other by filling the coil case with melted insulating resin through an open end of the coil case;
• and a low-voltage terminal socket holder inserted into an open end of said first cylindrical case at said open end of the coil case for communication with said internal assembly mounted therein, and an igniter mounted with a heat sink in an upper position in the socket holder, characterized in that then the holder is potted with insulating resin to the level at which the igniter and the heat sink are immersed in the resin and the holder is covered with a cap with ribs immersed in the resin to form a single solid unit;
• and further characterized in that the cap has a plurality of inwardly formed ribs for dispersing thermal stress to be applied to a molded resin layer.

An open-magnetic-circuit type engine ignition coil device comprising:

• a coil case composed of a first cylindrical case and a second cylindrical case having a small tubular hole in its center portion and an upper external shoulder at its open end fitted into an open end of the first case to form a closed end of the coil case;
• and an internal assembly consisting of a primary coil bobbin, a secondary coil bobbin with a projecting high-voltage terminal holder formed at a center of an end flange portion of the secondary coil bobbin a rod-shaped core, and a high-voltage terminal attached to the high-voltage terminal holder and having a contact for electrically connecting an ignition plug thereto, characterized in that the coil case and the internal assembly mounted therein with the high-voltage terminal holder press-fitted in the small tubular hole of the secondary case with a tip of the contact projected outwardly therefrom are integrally formed with each other by filling the coil case with melted insulating resin through an open end of the coil case;
• and a low-voltage terminal socket holder inserted into an open end of said first cylindrical case at said open end of the coil case for communication with said internal assembly mounted therein, and an igniter mounted with a heat sink in an upper position in the socket holder, characterized in that then the holder is potted with insulating resin to the level at which the igniter and the heat sink are immersed in the resin and the holder is covered with a cap with ribs immersed in the resin to form a single solid unit;
• and further characterized in that the holder cap has an air vent hole made therein.