IGNITION COIL UNIT FOR ENGINE AND ENGINE PROVIDED WITH PLASTIC HEAD COVER

摘要

To improve an anti-heat shock performance and an electric field concentration relaxation (an insulation performance) between a secondary coil and a center core, to attain a narrow diameter structure in an individual ignition type ignition coil and further to improve an assembling working of the ignition coil. The individual ignition type ignition coil is adopted to an engine having a plastic head cover. A secondary coil 3 is positioned at an inner side of a primary coil 5 and between a secondary bobbin 2 and a center core 1 a soft epoxy resin 17 is filled up. In the secondary bobbin 2, a secondary coil low voltage side is a potting side of the soft epoxy resin 17 and an inclination having a difference in an inner diameter is provided on the inner diameter in which the secondary coil low voltage side is formed large and secondary coil high voltage side is formed small. In the secondary bobbin, a thickness in the secondary coil low voltage side is formed thin and a thickness in the secondary coil high voltage side is formed thick. The soft epoxy resin 17 has a dent 17' according to a compression molding and has a glass transition point Tg which satisfies a condition of Äan allowable stress of the secondary bobbin > a generation stress at (from -40 DEG C to a glass transition point of an insulation resin)Ü. The secondary bobbin is formed by PPS and the primary bobbin is set to the primary coil at outer side of the secondary assembling body and under an assembling condition the winding is carried out.