Abstract: A controlled orifice for a hydraulic pressure control valve has a plunger and a conic orifice seat. The plunger has a head which forms a stagnation zone, and a rim with surfaces that define a sharp edge, these surfaces making an angle of at least 30 degrees with the conic bore orifice seat. A conic back surface extends to the plunger stem. The sharp edge of the rim forms a small annular vena contracta so that the regions where rapid flow is experienced are kept as small as possible. This reduces undesirable Bernoulli forces.

Abstract: An electro hydraulic servo valve has a pair of oppositely polarized magnets mounted in the surface of the spool of the valve to be controlled. A Hall effect sensor is mounted in the housing adjacent the magnets to precisely measure the position of the spool relative to the housing. The magnets and transducer are mounted on the longitudinal centerline of the spool to eliminate the spurious signals, due to temperature, vibrations, shock, hydraulic supply pressure and back pressure. The strength and spacing of the magnets and air gap are chosen to provide a linear output signal over the range of displacement desired and to provide the accuracy of location necessary for the particular configuration.

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 high speed high-performance valve member has a spool that is movable within a cylindrical cavity of a valve body or sleeve. The spool and sleeve are both formed of hardened stainless steel, but the bearing surfaces and lands of the spool are provided with a deposition layer of titanium nitride to give the bearing surface a hard smooth finish. The differential hardness between the spool and sleeve prevents galling. Damage due to cavitation is avoided, and the valve has a failure rate reduced by a factor of about twenty.

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.

Abstract: A rod seal for a linear hydraulic or pneumatic actuator cylinder includes a seal ring that has a bore that closely matches the diameter of the rods, proximal and distal cylindrical portions and a central annular flange. A seat in the actuator cylinder distal end assembly has proximal and distal cylindrical portions and a central void to receive the rod seal ring proximal and distal portions and central flange respectively. A radial clearance is provided so that the rod seal ring can travel radially, at least for a limited distance, while the rod passes axially through it. Static elastomeric ring seals are provided in the proximal, distal and central portions, and define pressure balancing regions. The rod seal assembly can be constructed at low cost, yet achieve a high degree of sealing with low axial friction characteristics.

Abstract: A rotary actuator includes a shaft rotatably mounted on a body, and a servovalve arranged to operate a vane motor for selectively rotating the shaft relative to the body. A portion of the shaft extends beyond the body. Supply and return passages are provided to the body and shaft so that fluid power supplied to the body is supplied to the servovalve and is also available at the end of the shaft beyond the body. Two or more such rotary actuators may be connected by intermediate brackets to provide a wrist actuator capable of movement about axes.