| 摘要 |
<p>PURPOSE:To obtain an ignition coil in which the storage amount of magnetic energy is increased and which can be made small and lightweight by a method wherein the edge of a first core coming into contact with a permanent magnet is made equal to the crosssectional area of the permanent magnet and the area of a protrusion part in which a part of the edge protrudes to the outside of a closed magnetic circuit together with a second core and the cross-sectional area of the permanent magnet and of the first core are set under a specific condition. CONSTITUTION:A permanent magnet 7 is inserted into a gap which is sandwiched between the edge 3b of a first core 3 and the inner side face 5b of a second core 5, and a closed magnetic circuit 9 is formed. When the area of a protrusion part 9b protruding to the outer circumferential direction of the closed magnetic circuit 9 is designated as SB, the area of the edge 3b is equal to the cross-sectional area SM of the permanent magnet 7, and the cross-sectional area of the second core 5 is equal to the cross-sectional area SF of the first core 3. At this time, under conditions of 2<SM<SF<6, 0<SB<SM<=0.25 and 0<SB/SF <=0.7, a good magnetic amount of magnetic energy can be part 9b, and the storage amount of magnetic energy can be increased. Thereby, the ignition coil can be made small and lightweight.</p> |
