INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To restrain combustion from deteriorating caused by the uneven quality of the exhaust emission having been introduced into a combustion chamber in an internal combustion engine wherein exhaust emission is introduced into the combustion chamber by opening a pair of exhaust valves during an intake stroke. SOLUTION: The internal combustion engine is provided with first and second exhaust valves arranged in a pair of exhaust ports individually connected to the combustion chamber, and first and second exhaust cams 51 and 52 provided at an exhaust cam shaft 50 to open and close the first and second exhaust valves respectively. These exhaust cams 51 and 52 are provided with main lift sections 51a and 52a to open and close their respective exhaust valves during an exhaust stroke and sub-lift sections 51b and 52b to open and close their respective exhaust valves during an intake stroke. The lifting quantity of the sub-lift section 51b in the first exhaust cam 51 is set larger than the lifting quantity of the sub-lift section 52b in the second exhaust cam 52.