Cam actuated valve assembly with hydraulic spring

Valve assembly for a cylinder in an internal combustion engine of the type having at least one cylinder with at least one valve seat and a cam which is rotated to reciprocate a valve to and from said seat, said assembly comprising

• a valve having a first end acted upon by said cam, an opposed second end brought to bear against said seat, and a stem extending between said ends, said stem having a first diameter which is uniform over a first section toward said first end and a second diameter which is uniform over a second section between said first section and said second end, said first diameter being larger than said second diameter,
• a housing having a closed chamber having a fixed volume defined by fixed rigid walls with opposed first and second coaxial bores which receive said stem therethrough so that said first and second ends are located externally of said chamber, said first bore closely receiving said first section, said second bore closely receiving said second section, said first and second diameters having a difference which is only sufficient to effect compression of a hydraulic fluid in said closed chamber during a complete rotation of said cam, whereby
• upon rotating said cam to move said first end toward said first bore and to lift said second end off said valve seat, the amount of said first section in said chamber increases while the amount of the second section in said chamber decreases, thereby decreasing the volume in said chamber not occupied by said valve stem by an amount sufficient to compress a hydraulic fluid in said chamber.