Ignition coil for internal combustion engines

An ignition coil for internal combustion engines, comprising:

• a casing molded of an insulating synthetic resin having a bottom wall with a step portion formed on the inside wall surface fixing a primary core, a side wall formed in a cylindrical shape surrounding said bottom wall, and a first opening portion surrounded with a free edge of said side wall;
• said primary core secured on said step portion formed on said bottom wall of said casing;
• a primary winding assembly including:
• a secondary core contacting said primary core at its both end face portions to form a closed magnetic circuit together with said primary core;
• a primary bobbin having a bobbin main portion formed cylindrical of an insulating synthetic resin surrounding the outer peripheral surface of a main portion of said secondary core, and at least one extended connecting portion extended from said bobbin main portion in a position offset in relation to said bobbin main portion, and extended to the upper surface of said primary core, for positioning said end face portion of said secondary core in relation to said primary core;
• and a primary winding with both ends of insulated wire constituting said winding electrically connected to first and second conductive terminals protrusively installed on said bobbin main portion;
• a secondary winding assembly including:
• a secondary bobbin formed cylindrical of an insulating synthetic resin, surrounding the outer periphery of said primary winding of said primary winding assembly;
• and a secondary winding wound on the outer peripheral surface of said secondary bobbin, with one end of an insulated wire constituting said winding electrically connected to said first terminal protrusively provided on said primary bobbin and with the other end of said insulated wire electrically connected to a conductive lead member protrusively provided on said secondary bobbin in a direction perpendicular to the axial direction of said secondary bobbin;
• and
• a conductive terminal member for closing a second opening portion formed in a part of a bottom wall of said casing, said terminal member being fixed with the peripheral surface thereof on the inside wall of said second opening portion and electrically connected with said lead member protruding from said secondary bobbin of said secondary winding assembly;
• whereby, said terminal member is to be connected to said spark plug of said internal combustion engine, said first terminal is to be connected to a power source battery of an electric circuit for ignition for said spark plug, and said second terminal is to be connected to a control circuit of said electric circuit for ignition.