Abstract: A rotary valve (10) is adapted to be associated with a fluid source (P) and a fluid return (R), and is adapted to control the flows of fluid (via control ports C.sub.1 and C.sub.2) with respect to the opposed chambers of a fluid-powered load. The valve has a body (11) provided with an elongated bore (12). The body has a plurality of passageways (23, 24, 25, 26) communicating spaced locations along the bore with the source, return and load control ports, respectively. A spool member (28) is rotatably mounted in the bore. The spool member has a passage adapted to cooperate with a body passageway so as to define at least one flow-metering port therebetween. The area of this flow-metering port or orifice (34) is a function of the angular displacement of the spool member relative to the body from a null position. The improvement comprises each of the upstream approach walls (32, 35) adjacent the orifice being relieved at an angle (.beta.) of at least 21.degree.

Abstract: A fluid intensifier (10) includes an unequal-area pump piston (11) and a drive piston (14). The large-area pump piston chamber (21) communicates with the small-area pump piston chamber (29) via a communicating conduit (30) having a check valve (25) therein. The pump piston is coupled to a drive piston (14) having a lost-motion connection (18) with a two-lobed pilot valve spool (41). The pilot valve (16) controls a pilot pressure in the spool end chamber (60) of a spring-biased control valve (19). The fluid intensifier is automatically reversing as the pump piston approaches either end of its stroke, and is arranged to provide a substantially-constant intensified fluid pressure (P.sub.i) at an outlet.

Abstract: A lightweight linear hydraulic actuator which is unusually inexpensive to fabricate includes a cylindrical barrel of metal tubing material, a head end gland and a rod end gland fastened to the barrel, a piston and a rod in the barrel with the rod extending through the rod end gland, ports in the sidewall of the barrel on opposite sides of the piston and fitting members having channels in registry with the ports, the fitting members including hoop type attachments around the exterior surface of the barrel and a curved surface mating with the curvature of the barrel. A circular groove is formed in the surface of the barrel around each of the ports and an O-ring seal is located in the grooves sealing against the curved surface of the fitting member. An axial extension forming part of each of the fittings includes a boss receiving a threaded fastener for fastening the fittings to the barrel.

Abstract: A hydraulic servo system to control flow rate of working fluid to a hydraulic motor as a function of command includes a spool-type pilot valve with manual or electrohydraulic structure for positioning the pilot valve and control conduits connecting the pilot valve to a flow control valve having lands and chambers between the lands for directing flow to the hydraulic motor, the flow control valve having a cylindrical cavity at one end and being exposed to full system pressure at the other end, a shuttle valve coaxially positioned with respect to the flow control valve having an axial extension extending into the cylindrical cavity, a spring in the cavity which tends to urge the flow control valve in a direction to oppose the system pressure, with control passages connecting opposite sides of the shuttle valve with the flow control valve chambers causing the shuttle valve to select the higher pressure in the flow control valve chambers and causing the spool to seek a position providing the desired flow rate.

Abstract: A direct drive servo valve includes a housing and a series of conduits connecting the housing to a fluid pressure source and to an associated actuator, a sleeve in the housing having a plurality of passageways interconnecting the conduits and a spool valve member rotatable within the sleeve to connect the conduits as desired, the spool valve being rotated by a torque motor. The torque motor rotor is connected to the return side of the fluid pressure source. The sleeve is formed of a series of disks which have a desired pattern of holes therethrough and which are bonded together to create a manifold structure having the desired pattern of passageways. A rotary variable differential transformer is connected to the spool and provides feedback signals to an external circuit controlling the torque motor. A torque rod is connected to the spool and the housing to provide a preload which tends to center or "null out" the spool position when there is no input signal.

Abstract: A high pressure pilot operated valve includes a housing with inlet and outlet passages, an internal bore communicating the passages and slide valve member movable between a first position blocking fluid flow and a second position permitting fluid flow. A spring in a low pressure chamber urges the slide valve member in the closing direction. A stem on the opposite end of the slide valve member is selectively exposed to a control pressure by means of a pilot valve connected to high pressure fluid to cause the slide valve member to move to the second position. The inlet passage communicates with the hollow interior of the slide valve member and with metering orifices in its sidewalls. A passage in the slide valve member having a radial conduit opening against the bore near its stem end connects the outlet passage with a low pressure chamber when the slide valve member is in the first position and is blocked when in the second position.

Abstract: A spool valve and seal having zero leakage includes a spool valve member having a hollow interior translatable within a bore in a valve body with inlet pressure connected through ports to the hollow interior of the spool valve member. A series of radial orifices axially displaced from the inlet ports communicate the interior with the exterior surface of said spool valve member, the outlets of said orifices terminating in chamfered edges. A seal is positioned adjacent the spool valve member in an annular groove formed in the surface of the bore within which the spool member is translated, the seal being positioned to prevent leakage between the inlet pressure passages and an outlet chamber in said valve body.

Abstract: A liquid spring accumulator includes a housing having inlet and outlet ports connected to a source of liquid under pressure. The housing contains a high pressure chamber and a cylindrical chamber containing a spring-loaded piston. A rod attached to the piston is movable therewith into the high pressure chamber. A passageway through the axis of the piston and rod provides communication between the inlet port and the high pressure chamber and includes a valve seat. A check valve member in the passageway includes a shaft holding the movable member off its seat during initial flow of hydraulic liquid into cylinder, permitting flow to fill the high pressure chamber. As the liquid pressure increases, the initial movement of the piston permits the check valve to close, and still further increases in pressure cause the piston to force the rod into the high pressure chamber, substantially increasing its hydraulic pressure.

Abstract: A combination hydraulic lock and pressure relief valve for use in an actuator system for operating a spoiler control surface is interposed between the retract side of the actuating piston and the servo valve controlling the piston. In this valve a poppet urged closed against a seat member by means of a light spring aided by the fluid pressure in the retract chamber of the piston holds the poppet closed whenever the system is shut down. A piston exposed to supply pressure carries a spring retainer which includes an elongated rod movable to dislodge the poppet from its seat to permit fluid to move toward and from the retract side of the piston during normal operation of the spoiler. A second retainer abuts against the seat and a heavy spring is interposed between the spring retainers. The seat member is loaded by the heavy spring to a predetermined level above normal system pressure.

Abstract: Life extending means for a typical spool type servo valve consists of a stack of washer-like disks which cooperate to define a number of finely divided flow paths across the stack in which initial flow, as the spool valve is opened, is forced through alternating chambers and orifices with measured pressure drops across the orifices and wherein subsequent increments of valve travel expose large openings providing flow rates versus travel comparable to conventional spool type valves.The individual disks may be made comparatively thin such that the thickness of two or more disks is required to provide a normal opening width into the stack. Thus a first disk and a second disk may have openings registering at identical positions to admit flow into the stack as a spool valve land passes the disks.

Abstract: Multiple path means for a fluid flow control device is shown in connection with a typical spool type servo valve. The multiple path means consists of a stack of washer-like elements or disks which cooperate to define a number of finely divided flow paths across the stack in which flow is forced through a series of alternating chambers and orifices with measured pressure drops across the orifices. Since many servo valves have comparatively short travel and since both control and wear problems tend to be most serious near null, it is desirable to minimize abrupt step flow gains around null.In the present disclosure individual disks, at least at the ends of the stack, are made comparatively thin such that the thickness of two or more disks may be required to provide a normal opening width into the stack.

Abstract: Quieting means for a fluid flow control device is shown in connection with a typical spool type throttling valve. The quieting means consists of a stack of washer-like members or disks which cooperate to define a large number of finely divided flow paths across the stack of disks. To provide a configuration which is very economical of space, the disks are arranged such that the flow path turns back and forth through different planes. Groups of flow paths are defined by a number of groups of three perforated disks confined between two imperforate disks. Two perforated disks having patterns of slots are positioned on opposite sides of a similar disk having a pattern of small orifices.

Abstract: Quieting means for a fluid flow control device is shown in connection with a typical spool type throttling valve. The quieting means consists of a stack of washer-like members or disks which cooperate to define a large number of finely-divided flow paths across the stack of disks. To provide a configuration which is very economical of space, the disks are arranged such that the flow path turns back and forth through different planes. Groups of flow paths are defined by a number of groups of three perforated disks confined between two imperforate disks. Two perforated disks having patterns of slots are positoned on opposite sides of a similar disk having a pattern of small orifices.