PURPOSE: To reduce the amount of HC which is likely to occur in an outer peripheral fringe section of a combustion chamber by forming auxiliary chambers which are slightly closer to a center of the combustion chamber than a peripheral wall of the combustion chamber in the outer peripheral fringe section of the combustion chamber and providing jet holes which are directed nearly in the direction of tangent of the combustion chamber and a jet hole which is directed toward the peripheral wall of the combustion chamber on the opposite side to the center of the combustion chamber in the auxiliary chambers.
CONSTITUTION: Auxiliary chambers 11, 12 are formed in an outer peripheral fringe section of a combustion chamber 1 of pent roof type which has two inclined faces 1a, 1b and on a ridge line α. Each auxiliary chamber 11, 12 has two first jet holes 11a, 11b; 12a, 12b and one second jet hole 11c, 12c. The first jet holes 11a, 11b; 12a, 12b face reversely each other and are directed roughly in the direction of tangent of the combustion chamber 1. On the other hand, the second jet hole 11c, 12c is directed toward a peripheral wall of the combustion chamber which is on the opposite side to an ignition plug 10. Since self-ignition is effected in the auxiliary chamber 11, 12 after air-fuel mixture is ignited by the ignition plug 10, the amount of HC which is likely to occur in the outer peripheral fringe section of the combustion chamber is reduced due to flame which is jetted from each jet hole and grows along the peripheral direction of the combustion chamber.
TERASHITA TOSHIYUKI
NAKAYAMA YOSHIAKI
YAMAMOTO HIROYUKI
