Patent ID: 7228838

Claim:
An internal combustion engine, comprising: a piston reciprocating in a cylinder; a crankshaft; and a multilink piston-crank mechanism linking the piston with the crankshaft and including: an upper link having a first end connected with the piston by piston pin; a lower link mounted rotatably on a crankpin of the crankshaft and having a first end connected with a second end of the upper link by a first connection pin; a control link having a first end connected with a second end of the lower link by a second connection pin; a control shaft connected movably with a second end of the control link and configured to rotate in synchronization with the crankshaft and at a half rotational speed of the crankshaft; and a phase adjusting section configured to variably adjust a phase of rotation of the control shaft relative to the crankshaft in accordance with an operating condition of the engine, the multilink piston-crank mechanism being configured to variably control a piston stroke characteristic of the engine, wherein the multilink piston-crank mechanism is configured to vary the piston stroke characteristic to allow a compression ratio of the engine in the case where a distance of piston stroke of the piston during an intake stroke is relatively short, to be higher than the compression ratio in the case where the distance of piston stroke of the piston during the intake stroke is relatively long.