PISTON FOR CYLINDER INJECTION INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To increase a suction valve lift amount at a top dead center through a valve recess and to prevent worsening of stratified lean combustion occasioned by the valve recess. SOLUTION: A protrusion part 21 of the top of a piston 4 comprises a slope 23 on the exhaust valve side and a slope 22 on the suction valve side in parallel to the slope of a pent roof type combustion chamber: a top horizontal surface 30 between the two slopes; and conical side faces 24 and 25 composed of a conical surface concentric to the outline circle of a piston 4. The outer periphery of the protrusion part 21 is provided with a piston reference horizontal surface 26. A cavity combustion chamber 12 is formed in the shape of a complete round and valve recesses 31 and 32 are recessed in a state to be superposed therewith. The depths of the valve recesses 31 and 32 are not deeper than the reference horizontal surface and the swirl component of the outer peripheral part of a cylinder flows over the piston reference horizontal surface 26, whereby no swirl component flows into the cavity combustion chamber 12.