| 摘要 |
PROBLEM TO BE SOLVED: To make the electrical field strength of a center core uniform and to reduce the size of the core, and then, to improve the output and insulating property of the core, by providing a positioning section which performs the centering of the secondary coil bobbin of a center core. SOLUTION: Projections 30 are provided at several locations on the inside of a secondary bobbin 3 so as to position the planar section of an inserted center core 7 with the projections 30. The space factor of the bobbin 3 is increased against the inside diameter of the bobbin 3 by forming the cross section of the core 7 in a polygon which is made closer to a circle, and the core 7 is inserted into the bobbin 3 after molding the outer periphery of the core 7 with rubber. Since the core 7 can be formed in a cylindrical state when conductive rubber is used for molding the outer periphery of the core 7, the electric field impressed upon a secondary coil becomes uniform and the insulating property of an igniter can be improved. Since the center core 7 is provided with magnets 12 for generating magnetic fluxes in the direction opposite to that of magnetic fluxes generated from a primary coil 2 and minus magnetic fluxes are given to the core 7, the magnetization curve of the core 7 can be utilized from the negative side to the positive side and the output of the coil 2 can be increased. |
