Abstract: The present invention includes an electropneumatic positioner having an external binary input block which provides access to the electrical output of an integral electronic position controller to control operation of a valve relay. The invention enables manual control of the positioner for safety, maintenance etc.

Abstract: A fluid control valve system for controlling the flow of hydraulic fluid supplied to and discharged out of an actuator having first and second actuator ports, comprising: a valve housing having a pressure sensing chamber for sensing the pressure of the hydraulic fluid introduced therein and a pressure port for introducing a hydraulic fluid; a valve spool axially movably received in the valve housing; valve spool operating means having the valve spool axially moved and including a force motor, a piston rod having the valve spool slidably received thereon and driven by the force motor, and a fixed piston firmly connected with the piston rod; and resiliently urging means for resiliently urging the valve spool along the center axis of the valve housing, the valve spool being urged by the hydraulic pressure of the hydraulic fluid in the pressure sensing chamber and the resiliently urging means to assume operation positions consisting of normal operation positions where the hydraulic pressure of the hydraulic fluid

Abstract: The invention relates to a hydraulic power steering system for motor vehicles, in the case of which the manual steering wheel is normally connected only by way of a control system with respect to the drive with a servomotor operating the steered vehicle wheels. In the event of a malfunctioning of the control system, a hydraulic forced coupling is automatically established between the servomotor and a hydraulic delivery unit which is constantly forcibly coupled with the steering handle, in order to form a "hydraulic linkage".

Abstract: The present invention provides a servo-actuator capable of operating in both the Fail Safe and Fail Operate modes. In the Fail Safe mode, a pretensioned spring member moves a jet pipe in the servo-valve to cause said actuator rod to move in a first direction upon loss of electric power. A mechanical feedback means coupled to said spring member and said actuator rod opposes the force applied by the spring so that when a force equilibrium is reached the actuator rod will be at a predetermined position.

Abstract: A method for optical signaling for electrical switch control, and in addition, optical powering of the electrohydraulic servovalve by means of opto-electric conversion using solar cells with a battery backup and dual redundancy for reliability. Optical power sources are e.g., laser diode, LED, or high intensity lamp.

Abstract: In a hydraulic power steering for motor vehicles having a steering control element, a position setting unit connected to the steering control element, a control motor connected to the position setting unit by way of a control circuit and a servo valve having control parts which are supported so as to be rotatable relative to each other but operatively interconnected by spring means retaining them in a central open position relative to each other, one of the control parts is operatively connected to the control motor and the other is connected to a steering gear mechanism associated with the steered wheels of the motor vehicle, and a hydraulic servomotor is associated with the vehicle wheel steering mechanism and hydraulically connected to the servo valve to receive hydraulic fluid therefrom depending on the relative rotary positions of the servo valve control parts.

Abstract: A fluid operated machine is monitored and regulated by providing a logic with a memory for storing the timings of properly operating functions, and detectors the outputs of which are used to calculate the actual operating timings of the functions. The actual operating timings are compared to the timings in the memory, and if they deviate beyond acceptable tolerances a warning signal is given. In addition to monitoring the timings, the device will also open or close control flow valves to bring the operating speeds of functions within acceptable tolerances.

Abstract: A control for a hydraulic drive or actuator is provided, wherein the actuator has pressurized operating fluid applied thereto, and wherein the operating fluid is directed through an electrically controlled valve for establishing the amount of operating fluid to be fed to the actuator. An electrical signal for controlling the valve is provided by a computing device. In the computing device, a predetermined desired value for the position (or travel), force, or pressure of the actuator or drive is continuously calculated based, at any given time, at least on one measured or simulated state variable indicative of a condition of the drive or actuator at the time of calculation. The calculated desired value determines the amplitude of the electrical signal directed to an electrical actuating device of the valve. The computing speed of the computing device for determining the respective desired value is faster than the actuating velocity or speed of the valve.

Abstract: A system of modular electrohydraulic servovalves is centrally controlled may be used to control the operation of critical hydraulic actuators. A programmable controller operates a group of modular servovalves which each deliver a portion of the total actuator fluid requirements. The flow rate, valve position, and valve pressure of each servovalve is monitored by the controller and compared to expected values in memory to determine whether a servovalve malfunction exists. If so, the controller maintains the required flow rate to the actuator by closing the malfunctioning valve and either activating a spare or proportionally increasing the flow rates of the remaining servovalves to compensate for the loss.

Abstract: An actuator for use in an active suspension system is controlled by a valve responsive to differential pressure across the piston of the actuator. The valve operates to allow movement of the piston so as to reduce the pressure differential. The valve is also controlled by signals indicative of position of and load applied to the actuator.

Abstract: In a stability compensating circuit of an actuator system which has an actuator that is actuated in response to an input signal and has an object to be controlled by the actuator and includes a vibrational component and wherein the stability of the actuator system is compensated by controlling a deviation signal between the input signal to the actuator and a feedback signal from the actuator, the improvement comprising a moving average filter for averaging the deviation signals to the actuator at intervals of a moving average time of the filter.

Abstract: A neutral position resetting device for a servo actuator is described, having reset means that is actuated when the control of the servo actuator by actuator valve means becomes inoperative. The reset means ordinarily separated from a spool of the actuator valve means resets the servo actuator to a neutral position by applying a driving force and forcibly moving the spool.

Abstract: A servo circuit with a failure detection mechanism comprising: a servo circuit for servo controlling on the basis of a control signal an actuator which is connected through a hydraulic circuit with a source of oil pressure and is operated by the hydraulic circuit which is changed over by a servo valve; a monitor circuit arranged in parallel relationship with the servo circuit and generating a monitor control signal; and a failure detection circuit in which the control signal of the servo circuit and the monitor control signal of the monitor circuit are inputted and which detects a failure of the servo circuit on the basis of the control signal and the monitor control signal; wherein the hydraulic circuit is provided with pressure detecting means for detecting a pressure thereof; and the monitor circuit includes a correction circuit in which a pressure signal from the pressure detecting means is inputted and which corrects a loop gain of the monitor circuit in correspondence with a value of the pressure signal

Abstract: Prevention of actuator oscillation due to failure mode in an aircraft pitch axis control system is provided by an oscillatory failure monitor. The oscillatory failure monitor provides power shutdown of the actuator through inner loop modeling and error signal processing of inner loop disturbances.

Abstract: An aircraft flight control system for use with a dual or tandem hydraulic actuator coupled to a flight control surface through an actuating rod. Each half of the tandem actuator is controlled by a respective electrohydraulic servovalve. Each electrohydraulic servovalve is controlled by signals applied to either of two actuating coils. Control signals are applied to the actuating coils from three controllers. The control signals are generated as a function of the difference between the flight control signal and a feedback signal indicative of the position of the actuating rod. Each electrohydraulic servovalve includes a pair of linear variable differential transformers generating feedback signals indicative of the position of the valve stem in each electrohydraulic servovalve. The valve feedback signals are compared to each other and to reference signals corresponding to the expected value of such feedback signals in order to detect and identify malfunctions in the flight control system.

Abstract: An improved booster for use with a master cylinder in a brake system is proposed which includes a spring for keeping the input shaft away from the booster piston. The spring has one end abutting on a piston acted by the auxiliary pressure from the auxiliary power source and the other end abutting on the brake pedal to bear the pedal stepping force. The input shaft will not engage the booster piston except in case of the failure of the auxiliary power source, ect.

Abstract: An actuator of the type used in aircraft flight controls and similar applications is combined with a fail-passive electrohydraulic control system (11) that affords the usual actuator response to electrical input commands during normal operation, and responds to any of a number of possible failure conditions to dispose the actuator in a passive or neutral failure mode. The passive-failure mode allows the actuator (15) to remain in the last-known valid position or move in response to an external force such as provided by a redundant backup actuator thereby avoiding a possibly dangerous flight condition that can result from a "hard over" actuator response to a failure condition.

Abstract: A hydraulic fluid powered actuation system preferably for controlling the position of a control surface of an aircraft in response to a plurality of redundant control signals is disclosed. The system comprises an actuator adapted to be mounted in the aircraft, comprising a housing having first and second cylinders with a piston moveably mounted within each of the cylinders. A piston rod connects the pistons and is adapted to engage the control surface. Two rotary torque motors having a common drive shaft are provided which are adapted to receive the plurality of redundant controls signals. First and second rotary control valves, coupled to the drive shaft, and thus, adapted to be driven by the rotary torque motors, are used to control the emission and exhaust of hydraulic fluid from the first and second cylinders, respectively. Preferably, there are four control signals and the torque motors are DC, multiple-poled torque motors with each coil on each torque motor coupled to a different control signal.

Abstract: A fast opening valve apparatus includes an electronic sensing circuit to determine when a positional error signal exceeds a predetermined reference value corresponding to an opening rate reference value. The sensing circuit provides a fast open command signal which is applied to a solenoid valve which is hydraulically coupled in parallel with a control servo valve. The control servo valve hydraulically couples a primary source of hydraulic fluid under pressure to a valve actuator which is mechanically coupled to a valve stem of an associated steam valve desired to be controlled. The activated solenoid valve opens a supplemental hydraulic fluid path between the valve actuator and the primary source of hydraulic fluid. To ensure an adequate hydraulic fluid pressure at the input of the servo valve and solenoid valve, an auxiliary source of hydraulic fluid under pressure may be coupled upstream of the servo valve and solenoid valve.

Abstract: An equalizer is arranged to continuously sense the control pressures of two valves. In the event of a differential between the control pressures, the equalizer operates to selectively adjust one valve so that the control pressures of both valves will thereafter be substantially equal.

Abstract: A control system for a fluid actuated control member is disclosed which uizes a pair of electrically controlled servo valves to control the supply of servo pressure fluid to a control valve piston. The pair of servo valves are electrically controlled such that, under normal conditions, one of the servo valves is operative to supply the servo pressure signal, while the other servo valve remains in an inert, open position. Upon the detection of a malfunction in the operative servo valve, electrical switches render the malfunctioning valve inert and transfer the operative capabilities to the second servo valve. The hydraulic control system does retain 100% of its performance capabilities following a malfunction of the initial servo valve.

Abstract: A fluid servo actuator control/damping mechanism and method which utilize and combine the functions of an electro-mechanically driven servo valve to achieve ram or actuator fluid flow and load control even after loss of fluid power as well as the main ram position control function under normal operating conditions.

Abstract: A redundant, dual-fail/operate fly-by-wire control system actuates a redundant tandem piston actuator (10) to provide a single composite output evidenced by movement of a piston rod (12). The basic fault-tolerate actuation system consists of dual hydraulic primary actuators, quadruplex electrical control loops (14-17), and control servo valves (22-25). A failure management system connects to the actuation system by means of lines (18-21) to control the servo valves (22-25). The four control loops (14-17) connect to a pilot controller that provides a pilot individual input signals to amplifiers (26-29) for each of the control loops. A tracking loop (450) includes switches (480, 482, 484) for connecting the four control loops (14-17) and providing isolation therebetween.

Abstract: A multiple-mode, multiplex pumping apparatus includes circuit control elements for initializing the apparatus by placing each of the pistons and plungers in each pumping section of the multiplex pumping apparatus at a respective initial starting point. The pumping apparatus also includes electronic circuit elements for controlling the inlet valves, exhaust valves and precompression valves of the hydraulic circuit of the pumping apparatus. The apparatus includes phase control circuit elements for controlling the separation of the leading edges of the plungers of two of the pumping sections of the apparatus when the apparatus is operating as a quadruplex pump. The pumping apparatus also includes elecrtronic circuit elements for insuring that each plunger of each pumping section stops at a fixed stopping point. The apparatus also includes electronic circuit elements for controlling the volume of fluid in the rod end portions of each of the pumping sections.

Abstract: A high resolution servo actuator is responsive to an electronic control or manual control. An output shaft having fast response and infinite positioning for stroking a manual servo valve on a pump is rotated by hydraulic power. A set of hydraulic working cylinders and centering cylinders are connected through a rack and pinion drive to a shaft. Centering cylinders utilize stop tubes to prevent its pistons from traveling past the center position and applying a constant force to center the shaft. A directional valve controls the flow of hydraulic fluid to the working cylinders for driving the shaft throughout its range of travel. An electrohydraulic servo valve converts the electronic control signal into hydraulic flow to the actuator. Shaft position feedback is developed and connected to the electronic control.

Abstract: Safety apparatus for an electrohydraulic servovalve. The safety apparatus includes a digital programmable switch (14) which is programmed to make switching decisions on the basis of whether or not the electrohydraulic servovalve is subjected to an external error and whether or not the electrohydraulic servovalve is free from internal error. Logic inputs that supply this information are provided to the programmable switch (14) by a logic device (16). On the basis of the logic inputs, the programmable switch (14) is programmed to interconnect, in a sequential manner, the analog electrohydraulic servovalve to one of four different analog drive systems. One of the drive systems is employed for the case whether there is no external or internal error, so that the electrohydraulic servovalve is in a normal mode of operation. Two of the drive systems are employed to quickly and safely de-energize the electrohydraulic servovalve upon the occurrence of an external error.

Abstract: An electro-hydraulic servo valve system comprising a two-stage spool type servo valve including a first stage comprising an electrical force motor and a second stage including a spool for controlling flow to an actuator. The force motor is operable upon receipt of a command electrical signal to move the spool. A first feedback is operable to cause the force motor to stop the movement of the spool. A second feedback is also operable to stop the movement of the spool at a predetermined position. The second feedback has a greater gain than said first feedback so that it normally dominates in the system. The second feedback comprises a pair of identical electrical sensors connected in parallel, and operable by movement of the spool.

Abstract: A redundant actuator system in which some of the sub-actuators have a lower force capability than the other sub-actuators. The lower force capability sub-actuators are controlled by a common electrical control circuit while the other sub-actuators are each independently controlled by separate control circuits. A plurality of hydraulic supplies power the sub-actuators, each supply powering one lower force capability sub-actuator, and at least one other sub-actuator.

Abstract: A redundant swashplate control system includes five or more actuators coupled to the swashplate. A feedback network independently controls each actuator to track a commanded position and a reference ram differential pressure that it related to the ram differential pressures sensed from all of the actuators.

Abstract: A redundant, dual-fail/operate fly-by-wire control system actuates a redundant tandem piston actuator (10) to provide a single composite output evidenced by movement of a piston rod (12). The basic fault-tolerate actuation system consists of dual hydraulic primary actuators, quadruplex electrical control loops (14-17), and control servo valves (22-25). A failure management system connects to the actuation system by means of lines (18-21) to control the servo valves (22-25). The four control loops (14-17) connect to a pilot controller that provides pilot individual input signals to amplifiers (26-29) for each of the control loops.

Abstract: A pair of input sense signals are processed and passed to inputs of two servo amplifiers. The amplifier outputs are summed and converted to a corresponding hydraulic pressure in a T-valve. Transducers monitor the produced pressure and provide feedback signals to the servo amplifiers. A comparator compares the servo amplifier outputs and activates a warning device if the signal difference therebetween exceeds a threshold level. Equalizer circuitry processes the comparator output and provides correction signals to the servo amplifier inputs to wash-out offset effects.

Abstract: A flight control system is provided for a helicopter furnishing safety feres, and providing back up control in the event of failure of controls of the rotary head swashplate of a helicopter. The swashplate is regulated by a series of actuators which are angularly positioned at particular settings around the swashplate. In the event of a control system failure, a supplemental system controls the selected settings for the swashplate, rotary head, and spar root and blade assemblies of the helicopter.

Abstract: Disclosed is a method of and apparatus to facilitate the operation of two servoactuators with a two/one (2/1) fail operational capability. In preferred embodiments, four signal processing channels are provided, two of which are active and directly control hydraulic servovalves which in turn controls the rate of operation of the servoactuators. Two other modeling channels produce an electrical output similar to the output expected from the servoactuator when supplied with the input to the active channel. The two actual rate indicative outputs and the two modeled rate indicative outputs are compared and deviations in one channel from the other three cause that channel to be declared a "failed" channel. Through a logical switching system, if an active channel has failed, the output of its associated model channel is connected to the servoactuator to continue operation of that actuator.

Abstract: An improved electrohydraulic servovalve has first and second valve spools mounted for independent sliding movement relative to a body in response to a common command signal. The valve has a first drive mechanism operatively arranged to cause a desired motion of one valve spool in response to the command signal, and has a second drive mechanism operatively arranged to cause a desired simultaneous similar motion of the other valve spool in response to the command signal. The improvement comprises a differential position sensing mechanism arranged to sense the relative positions of the two valve spools and operative to produce an output related to the difference therebetween, and an indicating device supplied with such output and operative to indicate substantially dissimilar relative positions of the spools.

Abstract: A hydraulic jack for the controlled displacement of a load, such as a platform used in the training of aircraft pilots, has a servo valve normally settable by an error signal Ve from an actuator including a subtractor followed by an amplifier, the subtractor emitting the error signal as the difference between an externally generated position-control signal Vc and a position-feedback signal Vx sent out by the jack. A monitoring device includes an error detector which generates a safety signal AL disconnecting the servo valve from its actuator whenever the position-feedback signal Vx deviates excessively from a reference signal V'x derived from the position-control signal Vc by means of a simulation circuit whose transfer constant equals, in first approximation, that of the servo system encompassing the jack and the actuator.

Abstract: In a system which provides feel-force to the control stick of an aircraft by means of hydraulic pressure, a fault indicating system which responds to excessive differences between desired and actual force in the actuator, only of a polarity in the same direction as concurrent stick motion, to separate pilot induced pressure excesses from force-system faults, is provided with directional sensitivity in the fault-indicating output logic. Excessive pressure errors in either direction of stick travel institute the monitoring of changes in stick position. Changes in stick position of an excessive magnitude are recognized as fault only if they occur in the same direction as the direction of excessive pressure error. A simple analog embodiment utilizes threshold detectors and a track store device; a dedicated-digital embodiment utilizes comparators, registers and a subtractor; and a computer embodiment utilizes a software routine.

Abstract: A hydraulic control system has two fluid supply circuits which control fluid pressure supplied to respective chambers of a fluid-controlled actuator, each chamber having an individual piston mounted on a common actuator rod. In normal operation, a major part of the pressure is supplied to the actuator by the first circuit in accordance with control signals derived from an external source. The second circuit supplies pressure to its respective chamber at a lower level in accordance with control signals derived from the differential pressure across the piston in that chamber, the pressure supplied by the second circuit acting to reduce the differential pressure across the piston. The system also includes a control unit that responds to malfunction of the first circuit or error in the control signals supplied to the first circuit, by disconnecting the first control circuit from control of the actuator, such as by equalizing pressure across the piston in the first chamber.

Abstract: An electrical system for circumventing failed servo valves or interconnecting wiring in an aircraft actuator control system having tandem-connected, redundant, electro-hydraulic servo valves. Triacs, in the simplest embodiment of the invention, are in bridge connection with the operating coils of the servo valves, and are utilized to sense the failed condition and to substitute a shunt impedance element at the open circuit in order to maintain the integrity of the remainder of the system. Alternate embodiments of the invention disclose in conjunction with the triacs, sensitive relays to achieve latched-circuit characteristics and optical isolation devices to further reliability of the system by isolating portions of the circuit from the power supply.

Abstract: An electromagnetic motor is provided with a samarium cobalt permanent magnet comprising a plurality of radially abutting segments. A combination of linear and non-linear springs with a force gradient larger than the magnetic force gradient facilitate motor operation in proportion to currents in electrical coils positioned on each side of the permanent magnet. Servoamplifiers independently control the current in each electrical coil in response to an input command signal, a motor position feedback signal and an actuator position feedback signal. A failure detection circuit detects coil failure by comparing current in each coil on one side of the magnet with the current in a corresponding coil on the opposite side of the permanent magnet. The circuit produces output signals to disconnect a defective coil and initiate an alarm. The circuit also detects power supply and motor position transducer failures by comparing their respective output voltage signals against predetermined reference voltages.

Abstract: A regulation system for steam turbines which includes a servomotor controlled by a servovalve (1) and two safety valves (31, 31') controlled by two electrically-operated valves (19, 19'). When the control inlet (7) of the servomotor is connected to the drain pipe (6) by at least one of the safety valves, the high-pressure fluid supply to the servovalve is simultaneously cut and the high-pressure fluid source is thereby prevented from discharging directly into the drain pipe. This enables high-pressure fluid sources having a low discharge rate to be used.

Abstract: A device for controlling hydraulic motors as in an aircraft "fly-by-wire" system wherein redundant hydraulic motors and controls are required to protect against failure of portions of the system or device. The device includes two master valves for controlling flow of fluid to and from the motors, one controlled by electrical signals from a command station and the other controlled mechanically through manual or automatic operation. There is a transfer valve for selecting which of the master valves is to be operable and to provide for smooth transition of control from the electrically controlled valve to the mechanically controlled valve.

Abstract: A control system for a fluid powered actuator arrangement which includes two drivingly interconnected hydraulic actuator devices, comprises two control valves which are movable in unison to apply operating pressure to the respective devices. The control valves being reponsive to four electro-hydraulic pilot valves, each of which is controlled by four nominally identical electrical input signals. The control system includes means for monitoring the electrical input signals and the operating pressures, and for isolating or rendering inoperative parts of the system in response to several combinations of malfunction indication.

Abstract: A modular control device which may be used separately or in predetermined multiples to provide desired detection and correction functions along with appropriate control functions normally associated with current day aircraft flight control. The module includes a housing which makes provisions for a plurality of bores capable of receiving various types of valve mechanisms therein. Control valves such as a servovalve and a solenoid valve are affixed to the housing and are hydraulically interconnected with the valves disposed in the various bores. The module may be connected to a hydraulic actuator which is moved to in turn position a load in accordance with control signals applied to the control module.

Abstract: A device for controlling hydraulic motors as in an aircraft "fly-by-wire" system wherein redundant hydraulic motors and controls are required to protect against failure of portions of the system or device. The device includes two master valves for controlling flow of fluid to and from the motors, one controlled by electrical signals from a command station and the other controlled mechanically through manual or automatic operation. There is a transfer valve for selecting which of the master valves is to be operable and to provide for smooth transition of control from the electrically controlled valve to the mechanically controlled valve.

Abstract: A combined feedback control system for a servo actuator including a ram that produces a mechanical displacement output of the system as directed by a position command signal. In the combined feedback control system a lever arrangement mechanically combines displacement and velocity information of the ram, and such combined information is conveniently transduced and electrically combined with the position command signal to develop an error signal that controls an electro-hydraulic valve. The latter preferably through a fluid amplification stage controls the delivery of fluid to the ram and, thus, the position thereof. Through the lever arrangement a mechanical failure control is operative to move the ram to a predetermined position upon failure of the electro-hydraulic valve and a manual control is operable to control the ram position via the fluid amplification stage.

Abstract: A control system is provided for a hydraulically operated tractor hitch assembly including a rockshaft operated by a main cylinder which is controlled through a spool valve operated by a pilot cylinder which is controlled, in turn, through a solenoid operated pilot valve. The pilot valve is controlled in response to a command signal and first and second feedback signals which correspond to the position of the rockshaft and to the position of the spool valve member. The velocity of the downward movement is limited by limiting the amplitude of a first error signal which is developed by a first comparator responsive to the command and first feedback signals with the first error signal and the second feedback signal being applied to a second comparator. Such velocity-limiting operations are controlled through a manually operated switch or by a motion sense circuit responsive to the rate of change of the command signal.

Abstract: An in-line actuator monitoring apparatus utilized in a redundant actuator system for determining which of the two redundant secondary actuators in a flight control system has failed and providing a disable signal to the failed actuator unit.

Abstract: A fail safe aircraft control system wherein duplicate control loops are employed to produce identical control signals for the system actuator. Output signals from the two loops are compared to detect when the outputs differ by a preset limit as an indication of a component failure. When such a failure is detected the system actuator is deactivated thus preventing the failed augmentation system from affecting control of the aircraft.

Abstract: A fail-safe fluid control valve including a first sleeve fixedly accommodated in a valve housing, a second sleeve reciprocably movably received in the first sleeve. The first and second sleeves are suitably grooved and ported, and the valve spool is formed properly with annular flanges. When there occur such abnormal conditions that the second sleeve and the valve spool are jammed or stuck to each other, the second sleeve is adapted to be moved in unison with the valve spool to actuate the fail-safe fluid control valve under entirely the same conditions as normal conditions.

Abstract: In a servocontrol device for controlling a control surface of an aircraft, which device is associated with a mechanical control member such as control column, wheel, pedals, and which comprises two identical double-acting hydraulic rams, integral with each other and each controlled by means of a slide valve, the slide valves each being controlled by a servovalve, whilst each servovalve is controlled by an electrical chain associated therewith, emitting an electrical control signal taking into account the displacements of said control member, the chains are connected to each other by crossed connections and they comprise apparatus for delivering equal signals to said servovalves.The invention is directed to the control of the control surfaces of an aircraft.