Patent ID: 8720395

Claim:
A variable compression ratio (VCR) apparatus installed in an engine rotating a crank shaft upon receiving combustion power of a mixer from a piston and changing a compression ratio of the mixer, the apparatus comprising: a connecting rod including: a small end portion having an eccentric bearing installation hole and rotatably connected to the piston through the eccentric bearing installation hole; a large end portion rotatably connected to the crank shaft such that the large end portion is eccentrically rotatable with respect to the crank shaft; and a space portion formed in a longitudinal direction of the connecting rod and communicated with the eccentric bearing installation hole of the small end portion; a piston pin fixedly provided in the piston; an eccentric bearing rotatably engaged to the eccentric bearing installation hole of the small end portion and coupled to the piston pin through a pin installation hole of the eccentric bearing, wherein the piston pin is offset from a center axis of the eccentric bearing; an eccentric link having a first end connected to the eccentric bearing; a variable link having a first end rotatably connected to a second end of the eccentric link; a control link having a first end rotatably connected to a second end of the variable link; and a control shaft provided in a second end of the control link to rotate the control link, wherein the eccentric link is rotated within the space portion.