INTERNAL COMBUSTION ENGINE

摘要

A multilink-type piston crank mechanism (25) is provided for an internal combustion engine. The mechanism (25) includes a piston (9) reciprocating within a cylinder bore (18) over a piston stroke distance, a crankshaft ( 1), an upper link (5) having one end connected to the piston (9) via a piston pin (8) and another end connected to a lower link (3) via an upper pin (4), the lower link (3) connecting the upper link (5) to a crankpin(2) of the crankshaft ( 1), and a control link (7) having one end connected to the lower link (3) via a control pin (6) and another end swingably supported by the engine. When the piston (9) is in the vicinity of top dead center, the lower link (3) moves in a lateral direction generally perpendicular to an axial direction of the crankshaft ( 1) and generally perpendicular to a direction of reciprocating motion of the piston (9), and an upper surface of the lower link (3) remains generally perpendicular to the direction of reciprocating motion of the piston (9).