INTERNAL COMBUSTION ENGINE HAVING SECONDARY AIR PASSAGE

PROBLEM TO BE SOLVED: To improve exhaust emission control performance by secondary air, and to miniaturize a cylinder head, by preventing the secondary air from being excessively heated by heat from a combustion chamber and an exhaust port. SOLUTION: The cylinder head 21 of an internal combustion engine has the exhaust port 31 opened in the combustion chamber 29 and a secondary air passage 80 introducing the secondary air for exhaust emission control to the exhaust port 31. The secondary air passage 80 is composed of an upstream passage 81 having an inlet 80i opened in the front wall 47a of the cylinder head 21, a downstream passage 82 having an outlet 80o opened in the exhaust port 31, and a bent portion through which the downstream passage 82 is bent and connected to the upstream passage 81. The secondary air passage 80 is positioned away from the exhaust port 31 with respect to the combustion chamber 29 in a cylinder axis direction, and an oil passage 60 is formed between the secondary air passage 80 and the exhaust port 31. COPYRIGHT: (C)2009,JPO&INPIT