Variable compression ratio apparatus

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.