| 摘要 |
PROBLEM TO BE SOLVED: To provide a three-point ignition type internal combustion engine improving combustion efficiency by avoiding lowering of burning speed due to quenching. SOLUTION: The internal combustion engine has second and third spark plugs 12, 13 respectively arranged in combustion chamber peripheral areas on both lateral sides of intake and exhaust valves which are almost symmetric positions with respect to a first spark plug 11 provided at a combustion chamber center. A combustion chamber concave portion 9b is formed in a top of a piston 10, which is formed of a cylindrical surface having a center line passing through discharge electrode parts 11g-13g of the respective spark plugs and a diameter larger than a distance between the discharge electrode part 11g of the first spark plug and the discharge electrode part 12g or 13g of the second or third spark plug. A time until burning flame generated from each electrode part reaches a piston wall and is quenched becomes long as a whole and the combustion efficiency is improved. COPYRIGHT: (C)2008,JPO&INPIT
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