Patent ID: 8667934

Claim:
An engine that has a compression ratio variable device, comprising: a crankshaft that is rotatably disposed on an engine block and a crank pin is disposed therein; a piston that reciprocates in a cylinder of the engine block; a connecting rod that connects the crank pin of the crankshaft with the piston; and the compression ratio variable device that varies a distance between the piston and the crank pin, wherein the compress ratio variable device includes: a block cover that is mounted on an outside of the engine block and a cover journal portion and a worm wheel mounting space are formed therein; a control shaft of which an exterior circumference contacts the cover journal portion to be rotatably supported by the cover journal portion and in which a worm wheel is disposed on one side thereof, and an operating arm protrudes from an exterior circumference of the control shaft; and a motor portion that is disposed at an outside of the block cover, wherein a worm connected to the motor portion is mounted to the block cover by penetrating the block cover, the worm being engaged with the worm wheel so as to rotate the control shaft according to the motor portion, wherein a distance between the piston and the crank pin is varied by a rotation of the control shaft.