Variable compression ratio apparatus for vehicle engine

A variable compression ratio apparatus for a vehicle engine that is mounted at the engine receiving combustion force of air-fuel mixture from a piston and rotating a crankshaft mounted between upper and lower cylinder blocks, and that changes compression ratio of the air-fuel mixture by changing a mounting height of the crankshaft according to a driving condition of the engine, wherein the mounting height is a distance between a cylinder head and the crankshaft, the variable compression ratio apparatus comprising:

• a supporter having a lower surface formed of a slanted surface and mounted between the upper and lower cylinder blocks so as to be movable therein, wherein the crankshaft is rotatably coupled to the supporter;
• an elastic member mounted at an upper portion of the supporter in the upper cylinder block so as to apply an elastic force to the supporter;
• a slider slidingly contacted to the slanted surface of the supporter so as to move the supporter toward or away from a cylinder and thus control the mounting height and slidingly supported by the lower cylinder block so as to be movable in a perpendicular direction to the slider;
• an operation unit rotatably mounted on the lower cylinder block and applying an operating force to the slider;
• and
• a power delivery unit connecting the slider with the operation unit to transmit the operating force of the operation unit to the slider.