Abstract: A hydraulic intake or exhaust valve actuator for an internal combustion engine has a generally cylindrical sleeve, a piston member formed with a head portion and a rod or shaft portion, and a rod bearing through which the rod portion slides axially. To accommodate wide temperature variations, the sleeve, piston member, and rod bearing, are all formed of the same material so as to have similar thermal expansion coefficients. Outer surfaces of the piston member head portion and rod portion are provided with a coating of titanium nitride, while corresponding inner surfaces of the sleeve and the rod bearing are provided with a hard coating of a different material, e.g. nickel boride. These coatings have different hardnesses, so that galling or adhesive contact is avoided.

Abstract: A hydraulic servo valve arangement of the type having a hydraulic amplifier followed by a spool type servo valve second stage, includes a deceleration control mechanism. A spindle-type positioner has first and second positions which respectively permit and block flow of fluid from the first amplifier stage to the first end of the second stage spool. The hydraulic actuator urges the positioner into its first position, and a spring urges the positioner into a second or closed position in the event a failure mode is encountered. A solenoid valve has a communicating port coupled through a dropping orifice to a source of fluid supply and a second port coupled to drain, such that in an actuated condition, input port is at high pressure but in an unactuated condition the input port drops to low pressure. Relief channels and in fluid communication with the one end of the spool member have metered orifices to limit the flow of hydraulic fluid when the spool transits to its null position.

Abstract: A flow limiter for use in association with a control valve for minimizing flow losses in an actuator control system to provide unrestricted control over the flow up to the desired maximum flow quantity value. A cylindrical sleeve is mounted within a housing and a piston is slidably contained within the sleeve to establish a variable chamber between the front wall of the piston and the back wall of the sleeve. A series of circumferentially spaced metering ports are contained in the variable chamber which are opened and closed by the piston. A control orifice is formed in the front wall of the piston and a biasing spring is arranged to act on the piston outside the flow path of the fluid to normally hold the piston in a home position wherein the metering ports are fully opened. The spring allows the piston to move toward a second position when the pressure over the orifice reaches a predetermined value, thus closing the metering ports to maintain the flow at a desired flow.