COMBUSTION CHAMBER FOR SPARK IGNITION TYPE ENGINE

摘要

PROBLEM TO BE SOLVED: To improve the heat efficiency and reduce NOx by providing an auxiliary combustion chamber and by improving the combustion performance of pre-mixed air-fuel mixture in a small-sized engine with a little exhaust quantity and a four-valve type engine. SOLUTION: The pre-mixed air-fuel mixture is spark ignited by an ignition plug 5 provided facing to the auxiliary combustion chamber 11 and the ignition flame is made to flow into a main combustion chamber 12. A facing metal fitting 15 having the projecting ignition plug 5 is projectively provided in the center of a piston opposite face of a cylinder head 1 and a squish guide face 16a and a flame guide top face 16b are formed under the facing fitting 15 and its internal circumference respectively. The auxiliary combustion chamber 11 is recessedly formed in the center of the piston top face 8a and the main combustion chamber 12 is recessedly provided in its outer circumference. A flame guide bottom face 17 opposite to the flame guide top face 16b is formed in the top face of a partition wall 13 partitioning the auxiliary combustion chamber 11 from the main combustion chamber 12. The ignition flame in the auxiliary combustion chamber 11 is made to flow into the main combustion chamber 12 inside via a clearance between the flame guide top face 16b and the flame guide bottom face 17.