Abstract: Hydraulic engine valve actuation methods for internal combustion engines having improved energy efficiency. In hydraulic engine valve operating systems using spring returns for valve closure, the spring force is a minimum when the valve is closed and a maximum at the maximum lift. The present invention takes advantage of this difference by using a valve opening hydraulic force which is greater than the spring force when the valve is closed and less than the spring force when the valve is open at its maximum lift. The valve actuator is controlled to allow the valve, when opening, to overshoot the equilibrium condition. During the overshoot, the hydraulic actuator backfills with actuating fluid at it normal actuating pressure. When the valve velocity decays to zero or near zero, the flow of hydraulic fluid to (and from) the valve actuator may be cut off, capturing the valve substantially at the overshoot position.

Abstract: Hydraulic engine valve actuation systems and methods for internal combustion engines. The systems utilize a proportional valve to regulate the flow of a working fluid to and from a hydraulic actuator controlling the engine valve position. The position of the proportional valve is controlled by one or more high speed valves to control various engine valve parameters, including engine valve takeoff and landing velocities. Returning all valves to a known starting position between engine valve events avoids accumulation of errors in proportional valve positioning. Embodiments using spool valves for the high speed valves and the proportional valve, and spring return and hydraulic return for the engine valve, are disclosed. A specially shaped spool in the proportional valve provides enhanced control over the engine valve operation. Various further alternate embodiments are disclosed.

Abstract: Hydraulic engine valve actuation systems and methods for internal combustion engines. The systems utilize a proportional valve to regulate the flow of a working fluid to and from a hydraulic actuator controlling the engine valve position. The position of the proportional valve is controlled by high speed valves to control various engine valve parameters, including engine valve takeoff and landing velocities. Returning all valves to a known starting position between engine valve events avoids accumulation of errors in proportional valve positioning. Embodiments using spool valves for the high speed valves and the proportional valve, and spring return and hydraulic return for the engine valve, are disclosed. A specially shaped spool in the proportional valve provides enhanced control over the engine valve operation. Various further alternate embodiments are disclosed.