Patent ID: 6966282

Claim:
An internal combustion engine variable compression ratio system comprising: an inner piston that is connected to a connecting rod via a piston pin; an outer piston that has a head portion facing a combustion chamber and that is fitted around the outer periphery of the inner piston so that the outer piston can slide only in the axial direction; restricting means fixedly provided on the outer piston so as to axially oppose the head portion with the inner piston interposed between the restricting means and the head portion; a first cam mechanism disposed between the inner piston and the head portion for controlling a first axial spacing therebetween; and a second cam mechanism disposed between the inner piston and the restricting means for controlling a second axial spacing therebetween, wherein the first cam mechanism includes a first rotating cam plate that is rotatable between first and second rotational positions around the axis of the inner piston, and is arranged so that the first cam mechanism axially compresses at the first rotational position of the first rotating cam plate so as to allow the first axial spacing to decrease and axially expands at the second rotational position so as to allow the first axial spacing to increase; wherein the second cam mechanism includes a second rotating cam plate that is rotatable between third and fourth rotational positions around the axis of the inner piston, and is arranged so that the second cam mechanism axially expands at the third rotational position of the second rotating cam plate so as to allow the second axial spacing to increase and axially compresses at the fourth rotational position so as to allow the second axial spacing to decrease; and wherein the first and second rotating cam plates are connected to driving means for moving the first rotating cam plate to the first rotational position and moving the second rotating cam plate to the third rotational position so as to hold the outer piston at a low compression ratio position, and for moving the first rotating cam plate to the second rotational position and moving the second rotating cam plate to the fourth rotational position so as to hold the outer piston at a high compression ratio position.