Cylinder head structure for multiple cylinder engines

Abstract

A cylinder head structure for a multiple cylinder engine, comprising, at least for each of its cylinders (1) located at either longitudinal end of its cylinder bank: a combustion chamber (13) defined by the cylinder and a piston received therein; an intake passage (18) communicated with an intake manifold (20) at its one end and with said combustion chamber at its other end; and exhaust passage (19) communicated with an exhaust manifold (21) at its one end and with said combustion chamber at its other end; at least one of said intake passage and said exhaust passage being curved toward a longitudinally central part of said cylinder bank as it extends from its other end to its one end. Hence, the size and weight of the intake manifold and/or the exhaust manifold can be reduced. In particular, if the passage is communicated with the combustion chamber by a pair of ports (14a, 14b, 15a, 15b, 14a', 14b', 15a', 15b', 58Ea, 58Eb, 58 Ia, 58Ib, 114a', 114b', 115a', 115b') controlled by valves and arranged along a longitudinal direction of the cylinder bank and different flow rates are assigned to these ports depending the operating conditions of the engine, a significant improvement in the performance of the engine may be attained by symmetrically arranging these ports with respect to a longitudinal center of the cylinder bank.