| 摘要 |
<p>An ignition coil unit for engines wherein the diameter of a coil of an independently ignitable ignition coil unit is reduced by improving resistance to thermal shock and relaxation of static focusing, i.e. insulation, between a secondary coil and a center core of the unit. The unit can be applied to an engine provided with a plastic head cover, and workability in assembling the unit can be improved. A secondary coil (3) is disposed inside a primary coil (5), and a soft epoxy resin (17) is filled between a secondary bobbin (2) and a center core (1). The bobbin (2) is designed so that the epoxy resin (17) is filled from the lower-voltage side of the secondary coil. The inside diameter of the bobbin (2) is tapered in such a manner that the lower-voltage side of the secondary coil is wider than the higher-voltage side, so that the thickness on the lower-voltage side of the secondary coil is decreased and the thickness on the higher-voltage side is increased. The epoxy resin (17) has a recess (17') formed by pressure-molding, and has a value Tg that satisfies the condition that an allowable stress of the secondary bobbin is greater than a stress caused at -40° C minus the glass transition point (Tg) of insulating resin. The bobbin (2) is made of PPS, and the primary coil is wound with a primary bobbin set outside the secondary coil assembly to wind both as an assembly.</p> |
