Spark-ignition internal combustion engine equipped with exhaust gas recirculation system

Claim 1

A spark-ignition internal combustion engine having a cylinder with a bore therein of a specified diameter, comprising: means defining a combustion chamber capable of producing squish turbulence of the air-fuel mixture supplied from the air-fuel mixture supply means of the engine, the combustion chamber defining means including a cylinder head having a radially disposed flat surface closing the upper end of the cylinder, said cylinder head having a hemispherical concavity formed concentrically with the bore of the cylinder, said hemispherical concavity forming a major part of the combustion chamber and being smaller in diameter at said radially disposed flat surface than that of the cylinder bore thereby defining an annular flat squish area and in which the diameter of said hemispherical concavity is in the range from 0.94 to 0.99 times of the diameter of the cylinder bore, and a piston reciprocally disposed within the cylinder and cooperating with said annular flat squish area to produce squish turbulence; exhaust gas recirculating means for recirculating the exhaust gases of the engine into the combustion chamber in the maximum amount of 10 to 50% by volume of the amount of the intake air which is inducted through the air-fuel mixture supply means into the combustion chamber; and a plurality of spark plugs disposed in the combustion chamber for igniting the air-fuel mixture containing the exhaust gases.