Patent ID: 6874489

Claim:
A combustion chamber structure for an internal combustion engine comprising: a piston ( 13 ), and a cylinder head ( 14 ), the combustion chamber being defined by a lower surface ( 14 a ) of an inner wall of the cylinder head ( 14 ) which confronts a cylinder bore ( 12 a ) and an upper surface of the piston ( 13 ) which slidably fits in the cylinder bore ( 12 a ), wherein a predetermined gap (α, β) is formed between the lower surface ( 14 ) of the inner wall of the cylinder head ( 14 ) and the upper surface of the piston ( 13 ), a squish area (A 2 ) is provided between a pair of valve recesses ( 13 d , 13 e ) formed adjacent to each other on the upper surface of the piston ( 13 ) in a direction of an axis (L 2 ) of a piston pin, and the gap (α, β) is formed such that the height thereof is higher at a circumferential center of the piston ( 13 ) than on circumferential sides thereof in the squish area (A 2 ).