Positive control (desmodromic) valve systems for internal combustion engines

A method for operating an internal combustion engine having a reciprocating piston operably disposed in a cylindrical bore of a sleeve valve, wherein the bore of the sleeve valve at least partially defines a combustion chamber, the internal combustion engine further comprising a rocker pivotally disposed between the sleeve valve and a cam lobe, the method comprising:

• moving the sleeve valve away from a valve seat to open a passage into the combustion chamber;
• while the passage is open, moving the piston toward a bottom dead center (BDC) position in the bore to draw a combustible charge into the combustion chamber;
• moving the sleeve valve toward the valve seat;
• pressing the sleeve valve against the valve seat with a first force to close the passage into the combustion chamber, the pressing of the sleeve valve against the valve seat with the first force comprising deflecting the rocker a first amount;
• while pressing the sleeve valve against the valve seat with the first force, moving the piston toward a top dead center (TDC) position in the bore to compress the combustible charge in the combustion chamber;
• as the piston approaches the TDC position, pressing the sleeve valve against the valve seat with a second force, greater than the first force, the pressing of the sleeve valve against the valve seat with the second force comprising deflecting the rocker a second amount which is greater than the first amount;
• and
• while pressing the sleeve valve against the valve seat with the second force, igniting the combustible charge to drive the piston toward the BDC position.