| 摘要 |
PROBLEM TO BE SOLVED: To provide a spark plug for a gas engine having a prolonged life without generating adverse effects on an ignition property, sufficiently conforming to a severe requirement of the life for a cogeneration system, a heat pump or the like. SOLUTION: An among gap of the spark plug 100 is formed by a plurality of gaps composed of a first gap gt formed by making a ground electrode 4 face the top end surface 13t of a central electrode 3, and a second gap gp formed by making the ground electrode 5 face the peripheral surface 13p of the central electrode 3. The length B of both gaps gt, gp are adjusted not shorter than 0.2 mm and not longer than 0.7 mm. Further, by defining the area of the central electrode 3 and the ground electrodes 4, 5, facing respective gaps gt, gp as an electrode facing area A (mm<SP>2</SP>), the electrode facing area A and the length B (mm) of the gaps gt, gp fulfills a relation of B≥0.1 exp(A/4). COPYRIGHT: (C)2003,JPO
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