Patent ID: 7353785

Claim:
An internal combustion engine variable compression ratio system comprising: a piston inner ( 5 a ) connected to a connecting rod ( 7 ) via a piston pin ( 6 ); a piston outer ( 5 b , 105 b ) that, while being fitted around the outer periphery of the piston inner ( 5 a ) so that it can slide only in the axial direction and having an outer end face thereof facing a combustion chamber ( 4 a ), is capable of moving between a low compression ratio position (L) close to the piston inner ( 5 a ) and a high compression ratio position (H) close to the combustion chamber ( 4 a ); a raising member ( 14 , 114 ) that is disposed between the piston inner and the piston outer ( 5 a , 5 b ), pivots around axes of the piston inner and the piston outer ( 5 a , 5 b ) between a non-raised position (A) at which movement of the piston outer ( 5 b , 105 b ) to the low compression ratio position (L) is allowed and a raised position (B) at which the piston outer ( 5 b , 105 b ) is held at the high compression ratio position (H), and allows, at the non-raised position (A), movement of the piston outer ( 5 b , 105 b ) between the low compression ratio position (L) and the high compression ratio position (H) by virtue of a spontaneous external force; an actuator ( 20 ) connected to the raising member ( 14 , 114 ); piston outer stopper means ( 18 ) that is provided between the piston inner ( 5 a ) and the piston outer ( 5 b , 105 b ), prevents movement of the piston outer ( 5 b , 105 b ) beyond the high compression ratio position (H), and allows movement of the piston outer ( 5 b , 105 b ) toward the low compression ratio position (L); and piston outer low compression ratio position latching means ( 30 a ) that is disposed between the piston inner ( 5 a ) and the piston outer ( 5 b , 105 b ) and operates, when the piston outer ( 5 b , 105 b ) has reached the low compression ratio position (L), so as to prevent relative axial movement of the piston inner ( 5 a ) and the piston outer ( 5 b , 105 b ); the system further comprising piston outer high compression ratio position latching means ( 30 b ) that is disposed between the piston inner ( 5 a ) and the piston outer ( 5 b , 105 b ) and operates, when the piston outer ( 5 b , 105 b ) has reached the high compression ratio position (H), so as to prevent relative axial movement of the piston inner ( 5 a ) and the piston outer ( 5 b , 105 b ).