Variable valve opening for an internal combustion engine

An internal combustion engine intake and exhaust valves comprising:

• a pushrod;
• a rocker arm pivoted between its ends and having one end engaged by the pushrod;
• a valve stem engaging the other end of the rocker arm;
• a selectively movable pivot supporting the rocker arm, the movable pivot having a lower rest position and an upper lock position, the upper lock position being determined by liquid trapped in a volume which is closed in response to upward movement of the pivot;
• the pivot having an intermediate lock position between rest position and the upper lock position;
• a check valve preventing trapped liquid from escaping when in a lock position;
• a radially extending passage through which liquid can pass;
• a first sleeve controllably movable for closing or opening one end of the passage;
• and
• a second sleeve movable in response to movement of the pivot for closing or opening the other end of the passage.

A method of operating an internal combustion engine having intake and exhaust rocker arms mounted on pivots for opening engine valves, each rocker arm engaged by a pushrod at one end and a valve stem at the opposite end, comprising:

• moving a rocker arm pivot in response to movement of a pushrod;
• and
• using a hydraulic block to hold the rocker arm pivot in or near a rest position;
• using a hydraulic block to stop the pivot movement at an upper lock position;
• and
• using a hydraulic block to stop the pivot movement at an intermediate lock position between the rest position and the upper lock position;
• using at least partially hollow member on which the rocker arm pivot is free to slide,
• using an outer sleeve engaging the rocker arm pivot which is free to slide on the outside of the member,
• using an annular chamber between the outside of the member and the inside of the outer sleeve having a hole through a wall of the member between the inside of the member and the annular chamber;
• and
• using a hydraulic block to permit flow or blocks flow through the hole;
• and
• using a spring which is deformed before the pivot reaches a lock position, with a first portion of the stroke of the spring smoothly continuous with a relatively lower force/displacement slope and a second portion of the stroke of the spring being smoothly continuous with a relatively higher force/displacement slope.