Patent ID: 8074612

Claim:
A variable compression ratio apparatus for an engine receiving a combustion force of an air-fuel mixture within a piston chamber so as to drive a vehicle, wherein the apparatus is configured to change compression ratio of the air-fuel mixture within the piston chamber, the apparatus comprising: an upper connecting rod having one end rotatably connected to the piston so as to receive combustion force of the air-fuel mixture; a lower connecting rod having one end rotatably connected to a second end of the upper connecting rod and rotated by the combustion force of the air-fuel mixture received from the upper connecting rod; a crankshaft eccentrically mounted to the lower connecting rod so as to be rotated thereby; a control rod provided with one end rotatably connected to a second end of the lower connecting rod so as to change the path of motion of the lower connecting rod; a control shaft eccentrically and rotatably connected to a second end of the control rod and changing a position of the other end of the control rod; and a planetary gear set that receives torque from a driving unit and changes phase angles of the crankshaft and the control shaft.