Showing papers on "Hydraulic machinery published in 2000"

Adaptive robust motion control of single-rod hydraulic actuators: theory and experiments

Abstract: High-performance robust motion control of single-rod hydraulic actuators with constant unknown inertia load is considered. The two chambers of a single-rod actuator have different areas, so the dynamic equations describing the pressure changes in them cannot be combined into a single load pressure equation. This complicates controller design since it not only increases the system dimension but also brings in the stability issue of the added internal dynamics. A discontinuous projection-based adaptive robust controller (ARC) is constructed. The controller takes into account not only the effect of parameter variations coming from the inertia load and various hydraulic parameters but also the effect of hard-to-model nonlinearities such as uncompensated friction forces and external disturbances. It guarantees a prescribed output tracking transient performance and final tracking accuracy in general while achieving asymptotic output tracking in the presence of parametric uncertainties. In addition, the zero error dynamics for tracking any nonzero constant velocity trajectory is shown to be globally uniformly stable. Experimental results are obtained for the swing motion control of a hydraulic arm and verify the high-performance nature of the proposed strategy. In comparison to a state-of-the-art industrial motion controller, the proposed algorithm achieves more than a magnitude reduction of tracking errors. Furthermore, during the constant velocity portion of the motion, it reduces the tracking errors almost down to the measurement resolution level.

Electrokinetic high pressure hydraulic system

Abstract: An electrokinetic high pressure hydraulic pump for manipulating fluids in capillary-based systems includes (i) a microchannel having a fluid inlet and outlet and a porous dielectric material disposed in said microchannel; (ii) an electrolyte contained within said microchannel and in communication with the porous dielectric material; (iii) spaced apart electrodes that are in contact with said electrolyte; and (iv) means for applying an electric potential to said spaced apart electrodes. The pump, which requires no moving mechanical parts, uses electro-osmotic flow to generate high pressures for pumping and/or compressing fluids, for providing valve means and means for opening and closing valves, for controlling fluid flow rate, and for manipulating fluid flow particularly in capillary-based systems. The compact nature of the high pressure hydraulic pump permits construction of a micro-scale or capillary-based HPLC system that fulfills the desire for small sample quantity, low solvent consumption, improved efficiency, running parallel samples and field portability. Control of pressure and solvent flow rate are achieved by controlling the voltage applied to the electrokinetic pump.

Flight test experience with an electromechanical actuator on the F-18 Systems Research Aircraft

Abstract: Development of reliable power-by-wire actuation systems for both aeronautical and space applications has been sought to eliminate hydraulic systems from aircraft and spacecraft and thus improve safety, efficiency, reliability, and maintainability. The Electrically Powered Actuation Design (EPAD) program was a joint effort between the Air Force, Navy, and NASA to develop and fly a series of actuators validating power-by-wire actuation technology on a primary flight control surface of a tactical aircraft. To achieve this goal, each of the EPAD actuators was installed in place of the standard hydraulic actuator on the left aileron of the NASA F/A-18B Systems Research Aircraft (SRA) and flown throughout the SRA flight envelope. Numerous parameters were recorded, and overall actuator performance was compared with the performance of the standard hydraulic actuator on the opposite wing. This paper discusses the integration and testing of the EPAD electromechanical actuator (EMA) on the SRA. The architecture of the EMA system is discussed, as well as its integration with the F/A-18 flight control system. The flight test program is described, and actuator performance is shown to be very close to that of the standard hydraulic actuator it replaced. Lessons learned during this program are presented and discussed, as well as suggestions for future research.

Rotary steerable well drilling system utilizing hydraulic servo-loop

Abstract: An actively controlled rotary steerable drilling system for directional drilling of wells including a tubular rotary tool collar having rotatably mounted thereabout a substantially non-rotatable sliding sleeve incorporating a plurality of elastic coupling members to maintain the sliding sleeve in coupled relation with the borehole wall during drilling. An offsetting mandrel is supported within the tool collar by a knuckle joint for pivotal movement and is rotatably driven by the tool collar and has a lower end extending from the collar and adapted for support of a drill bit. To achieve controlled steering of the rotating drill bit, orientation of the drilling tool is sensed by navigation sensors and the offsetting mandrel is maintained geostationary and selectively axially inclined relative to the tool collar by orienting it about the knuckle joint responsive to navigation sensors. An alternator and a hydraulic pump, located within the tool collar, are driven by a power source driven by the flowing drilling fluid to produce electric power and hydraulic pressure for supplying electrical power for the electronics package of the tool and for actuation of hydraulic system components. Hydraulic cylinder and piston assemblies, actuated by tool position signal responsive servo-valves, control the angular position of the offsetting mandrel with respect to the tool collar. The hydraulic pistons are servo-controlled responsive to signal input from the navigation sensors and from other tool position sensing systems which provide real-time position signals to the hydraulic position control system.

Cavitation of hydraulic machinery

Abstract: Introduction (S C Li) Cavitation and Cavitation Types (A J Acosta) Bubble Dynamics: Single Bubble (A Shima) Bubble Dynamics: Multi-Bubbles (Stochastic Behaviour) (S C Li) Cavitating Flow (H Mural & E Outa) Cavitation Phenomena in Hydraulic Machinery (H Tanaka, R K Turton et al.) Cavitation Damage to Hydraulic Machinery (Y Iwai et al.) Cavitation Caused Vibrations (J Sato, P Henry et al.) Unsteady Cavitation Flows Caused by Machine Transients: Turbine Transients (C S Martin) Unsteady Cavitation Flows Caused by Machine Transients: Pump Transients (H Tsukamoto).

Negative Pressures and Cavitation in Liquid Helium

Abstract: Cavitation—the formation of bubbles—is a familiar phenomenon. Whenever a liquid is agitated violently, there is a possibility that cavitation will occur (see, for example, figure 1). In the case of boat propellers or hydraulic machines, cavitation is a problem that engineers try to avoid. In other contexts, however, cavitation can be useful—as, for example, in ultrasonic cleaning devices.

Hydraulic latch pin assembly for coupling a tool to a construction equipment

Abstract: The invention provides a coupling assembly and method for coupling a tool to a dipperstick, or arm, on an apparatus which has a hydraulic system for moving the tool. The coupling assembly includes a coupler body having link structure for pivotally coupling to the dipperstick. A latch member is movable between an engaged position for engaging the tool and a disengaged position for disengaging from the tool. A spring is arranged to provide a spring force to urge the latch member to the engaged position. A hydraulic motor has a part that is stationary relative to the coupler body and a movable part that can be extended relative to the stationary part when hydraulic pressure is applied to one end of the hydraulic motor. The movable part is coupled to the latch member such that extension of the movable part urges the latch member to the retracted position in opposition to the spring force.

Observer based coordinated adaptive robust control of robot manipulators driven by single-rod hydraulic actuators

Abstract: This paper studies the coordinated motion control of a hydraulic arm driven by single-rod hydraulic actuators (a scaled down version of an industrial backhoe/excavator arm). Compared to conventional robot manipulators driven by electrical motors, hydraulic arms have a richer nonlinear dynamics and strong couplings among various joints (or hydraulic cylinders). This paper presents a physical model based adaptive robust controller (ARC) to explicitly take into account the strong coupling among various hydraulic cylinders (or joints). In addition, an observer is employed to avoid the need of acceleration feedback for ARC backstepping design. Theoretically, the resulting controller is able to take into account not only the effect of parametric uncertainties coming from the payload and various hydraulic parameters but also the effect of uncertain nonlinearities. Furthermore, the proposed ARC controller guarantees a prescribed output tracking transient performance and final tracking accuracy while achieving asymptotic output tracking in the presence of parametric uncertainties. Simulation and experimental results are presented to illustrate the proposed control algorithm.

Hydraulic system, manifold and volumetric compensator

Abstract: A hydraulic system manifold having a body, a counterbalancer in the body and a flow controller in the body is disclosed. The body has first and second pump ports, first and second cylinder ports, first and second compensator ports and first and second supply conduits in communication with the first and second pump ports, the counterbalancer and the flow controller. The counterbalancer is in communication with the first and second supply conduits and the cylinder ports, to communicate hydraulic fluid between the first and second supply conduits and the first and second cylinder ports while counterbalancing hydraulic fluid pressure in the first and second supply conduits. The flow controller is in communication with the first and second supply conduits and the compensator ports, to control the flow of hydraulic fluid between the compensator ports and the first and second supply conduits to supply and store hydraulic fluid in a volumetric compensator in communication with the compensator ports.

Hydraulic system providing down force on a work implement

Abstract: A hydraulic system (20) for controlling the seed/fertilizer supply system (10) and the down pressure on a plurality of individual row units (12). A secondary supply arrangement (60) interconnects a first control circuit (26) of supply system (10) with a second control circuit (28), when the row units (12) are in a float mode, to provide pressurized fluid for the down force on the row units (12) during operation.

Optical Measurement Techniques for Experimental Analysis of Hydraulic Turbines Rotor - Stator Interaction

Abstract: The progress of optical experimental techniques, LDV and PIV, allows to access the unsteady 3D velocity field and the complete Reynolds stress tensor, in real configuration of hydraulic test models. A description of the rotor/stator interaction, at the runner inlet and outlet, is presented for a hydraulic turbine industrial model. The experimental results lead to a better understanding of the rotor-stator interaction and of the influence of the unsteady components in a hydraulic machine operation.

Multiplier digital-hydraulic well control system and method

Abstract: A system for transmitting hydraulic control signals or hydraulic power to downhole well tools while significantly reducing the number of hydraulic lines required Hydraulic control signals are furnished at relatively low pressures to actuate a selected well tool, and the hydraulic pressure is selectively increased over a threshold level to provide hydraulic power to the well tool The hydraulic control actuation signals can be controlled by selectively pressurizing different hydraulic lines in a selected sequence and by selectively powering the fluid pressure within a selected hydraulic line The combination of selective sequential actuation and selective fluid pressure provides multiple actuation combinations for selectively actuating downhole well tools Additional combinations can be provided by changing the pressurization sequence, magnitude, absolute time, duration, and pressurization profile within a discrete time period

Brake device for elevator

Abstract: A brake device for elevator, including a hollow box-shaped elevator car (1) for holding the passenger or luggage; block (5) having a pair of guide rails (6) for guiding upwards and downwards the elevator car (1); a plurality of racks (4) disposed at the block (5) along the lifting direction in vertical; at least one motor (2) tooth-engaged with at least one pinion (2a) at the racks (4), for lifting upwards and downwards the elevator car (1), clutch (12) for controlling power transmission to connect a driving shaft (19) to a driven shaft (20) when the pinions (11) engaged with the racks (4) are rotated at high speed due to elevator crash; hydraulic pump (15) for generating hydraulic pressure from power transmission through a plurality of transmission gears (13) when the clutch (12) delivers rotation; and a plurality of hydraulic cylinders (17) for braking the elevator by brake pad (18) in tight coupled with the guide rails (6) by hydraulic power from the hydraulic pump (15). When fall of the elevator is detected, hydraulic pressure actuates the brake pad to brake the elevator and the brake device utilizes friction with less impact, thereby protecting the passengers or luggage from sudden impact.

Hybrid electric power generator and method for generating electric power

Abstract: A system for generating electric power comprises an electrically driven air compression unit ( 10 ), a high-pressure storage tank ( 14 ) and a hydraulic system. The hydraulic system comprises a fluid reservoir ( 20 ), a pneumatically driven fluid pump ( 18 ) and a hydraulic motor ( 26 ), having a drive shaft ( 28 ) rotatably coupled to an electric generator ( 8 ). Initially a high-speed compression unit ( 10 ) is operated by an outside electric source. The air is compressed into the high-pressure storage tank ( 14 ) and controllably released into the pneumatically driven fluid pump ( 18 ), causing its operation. Hydraulic fluid being pressured from the fluid reservoir ( 20 ) into the hydraulic motor ( 26 ) causes the rotation of the motor drive shaft ( 28 ) and the electric generator ( 8 ). Electric power is generated. The outside electric source is removed. Part of the generated power is used to operate the compression unit ( 10 ) the other part of the power is used by a load.

Braking pressure control apparatus having device for diagnosing manually operated hydraulic system

Abstract: A braking pressure control apparatus for a hydraulically operated brake, including a first hydraulic system having a first hydraulic pressure source power-operated to pressurize a working fluid and capable of controlling the fluid pressure, for operating the brake, a second hydraulic system having a second hydraulic pressure source operable by an operating force acting on a manually operable brake operating member, to pressurize the working fluid to a pressure higher than a level corresponding to the operating force, for operating the brake, a switching device operable to selectively establish a first state in which the brake is operated with the pressurized fluid delivered from the first hydraulic pressure source, and a second state in which the brake is operated with the pressurized fluid delivered from the second hydraulic pressure source, and a diagnosing device operable to diagnose the second hydraulic system on the basis of the fluid pressure in the second hydraulic system.

Toward Safe and Human Friendly Hydraulics: The Passive Valve

Abstract: Hydraulic systems, as power sources and transmissions, offer many advantages over electromechanical or purely mechanical counterparts in terms of power density, flexibility, and portability. Many hydraulic systems require touching and contacting the physical environments; and many of these systems are directly controlled by humans. If hydraulic systems are passive, they would be both safer to interact with, and easier for humans to control. In this paper, it is shown that a critical hydraulic component, the directional control valve, is not passive. However, the directional valve, as a one-port or a two-port device can become passive if appropriate spool valve dynamics are imposed. Methods to passify the valve for both first-order and second-order spool dynamics are considered. In the case of second-order spool dynamics, a passive method that relies on hardware modification, and an active feedback method, are proposed.

Electrically controllable biasing differential

Abstract: A differential gear assembly has a friction clutch for variably restricting differential action. A simple hydraulic piston mechanism is used to amplify the axial force generated by the electric coil and mechanical ball ramp mechanism. The hydraulic system consists of an annular primary piston in contact with the clutch pack, and a multiple set of secondary pistons are attached to the unrestrained ball ramp race. Hydraulic fluid fills the cavity between the primary and secondary pistons. This system provides force multiplication proportional to the surface areas of the respective piston faces.

Valving Land Phenomena of the Innas Hydraulic Transformer

Abstract: The design of a hydraulic pump or motor with a variable displacement could be much simpler, if a rotating valve plate could be used to vary the displacement. An essential aspect of the rotating valve plate is however that the passage of the cylinder ports from one kidney to the other often occurs while the pistons are moving. Experiments have revealed that this leads to high pressure spikes and cavitation. Because of this it is an unwritten rule that in hydraulic pumps and motors the passage of the so-called valving lands has to take place in the top and bottom dead centres.Against this rule there is a new hydraulic transformer developed (the Innas Hydraulic Transformer or IHT) in which the rotating valve plate is introduced again. Instead of varying the displacement the position of the valve plate now defines the pressure ratio between the load and the supply port. As will be shown this has a crucial effect on the valving land phenomena. Instead of increasing pressure pulsations and cavitation th...

All-hydraulic powered horizontal stabilizer trim control surface position control system

Abstract: A control system utilizes hydraulic power only to control a fixed-wing aircraft horizontal stabilizer trim control surface with no electrical control devices except for a cockpit pilot/co-pilot initiated 3-position spring-centered toggle trim switch, a backup electrical motor and a standard electronic logic pilot interface. The toggle trim switch controls two solenoid valves which control the operation of a directional control valve. The control system also includes a hydraulic motor, a rate control valve, a blocking-bypass valve, a shutoff valve with an integrated position sensor and a gear set driving an acme threaded output shaft for elevating or lowering the horizontal stabilizer trim control surface on command by the pilot. The control system controls the horizontal stabilizer trim control surface angular displacement rate as a function of angular position by means of a mechanical feedback linkage between the spool of the rate control valve and the horizontal stabilizer trim control surface. The sleeve of the rate control valve has a variable outflow area slot to control the hydraulic flow rate to the motor ports of the hydraulic motor. The horizontal stabilizer trim control surface is automatically stopped at pre-determined maximum-up/maximum-down positions by means of a mechanical feedback linkage between the horizontal stabilizer trim control surface and the spool of the shutoff valve. If the mechanical feedback linkage between the rate control valve spool and the horizontal stabilizer trim control surface malfunctions, the rate control valve automatically reverts to a default fixed flow rate which translates into a corresponding fixed horizontal stabilizer trim control surface angular displacement rate.

Dynamics and control of accumulators in continuous strip processing lines

Abstract: Accumulators in a strip processing line are primarily used to allow for rewind or unwind core change while the process continues at a constant velocity. Accumulators facilitate continuous operation of the process line and thus constitute an important element of a continuous strip processing line. This paper studies the coupled dynamics of the accumulator carriage motion, rollers, and web spans. Suggestions are made in an effort to integrate the tension dynamics of individual spans in an accumulator. An average dynamic model that integrates the dynamic models of individual spans in the accumulator is derived. This aggregation of the dynamics can facilitate control design for the accumulator carriage. Hydraulic system modeling associated with the accumulator is studied. Aspects of the hydraulic system such as drop due to friction in long pipes and dominant damped resonant frequency of the hydraulic system are discussed. A compact state-space model of the dynamic model of the accumulator is obtained from the average span tension dynamics, carriage dynamics, and pressure dynamics. Some experiments conducted on an ALCOA Corporation continuous process line are discussed.

Tap Water as a Hydraulic Pressure Medium

Abstract: Using water in hydraulic systems introduction to water physical properties of water water chemistry water microbiology corrosion in aqueous systems water treatment.

Non-linear Control Based on Physical Models: Electrical, Mechanical and Hydraulic Systems

Abstract: Fundamentals.- Some non-linear control design strategies.- Electromagnetic systems.- Mechanical PCH-systems.- Hydraulic drive systems.

Hydraulic rotary grinder for attachment to construction machinery

Abstract: A hydraulic rotary grinder for attachment to construction machinery such as an excavator, consisting of a rotating drum having a hollow core and a plurality of attached replaceable grinding tips. A hydraulic motor rotates the drum, and is secured within the hollow core and activated by the hydraulic system of the construction machinery. A planetary gearbox is associated with the hydraulic motor to provide speed changes. At least one weight within the hollow core provides shock absorption and additional mass to the rotating drum. A heat-absorbing liquid within the hollow core absorbs heat from the grinding operation and a seal prevents the heat-absorbing liquid from leaking out of the drum. A number of water nozzles may be mounted on the apparatus for dust suppression. A second hydraulic motor may be provided for increased torque and grinding capacity.

Vehicle generator control

Abstract: Control apparatus for maintaining constant speed of an AC generator carried aboard a motor vehicle having an engine, a transmission including a power take-off, and an AC generator. The control apparatus includes a hydraulic pump driven from the power take-off, a hydraulic motor drivably connected to the generator, a fluid circuit driving the hydraulic motor from the hydraulic pump, a closed center proportional servo control valve assembly controlling the fluid circuit, and a control circuit disposed to control the proportional control valve assembly. The control circuit includes an eddy current detecting speed sensor disposed to sense rotational speed of the hydraulic motor, or alternatively, includes an AC generator frequency reference signal generator, a comparing subcircuit which compares sensed speed of the hydraulic motor to a reference signal provided by a digital variable pulse generator, manual controls, an automatic ramp generator which controls acceleration of the generator such that acceleration proceeds gradually from a stopped condition to full operating speed, an annunciating display, and a main circuit breaker. The control valve assembly throttles both pressurized fluid entering the valve assembly from the pump and also spent fluid being returned to the pump through the valve assembly, thereby equalizing pressure drop on each side of the valve assembly. The hydraulic system includes a fluid storage tank, an oil filter, and an oil cooler.

Control device of an internal combustion engine

Abstract: A controller for an internal combustion engine has a hydraulic valve characteristic changing mechanism for changing valve operating characteristics of suction and exhaust valves; a valve system provided with a hydraulic valve phase variable mechanism that changes the phase; a map that stores a fuel injection quantity and an ignition timing in response to the valve operating characteristics; and delay time setting means for setting a delay time required to complete changeover of the valve operating characteristics, based on operating oil properties detected from behavior of a valve phase variable mechanism, to change the map after the delay time has elapsed. Thus, a valve operating characteristic changing timing coincides with a map changing timing to thereby achieve an improved performance of the internal combustion engine.

Apparatus for swaging ferrules

Abstract: Apparatus (16) for swaging a ferrule or ferrules onto an outer wall of a cylindrical member includes a hydraulic power section (14) and an adapter tool The hydraulic section is disposed within a housing (12) and the adapter tool (112) is at least partly retained in the housing and also is fully removable from the housing without affecting the hydraulic power section of the apparatus The hydraulic section includes a piston that is moved under force of hydraulic pressure applied thereto from a hydraulic pressure source The adapter tool includes a driven swaging die (70) that is moved from a retracted position to an extended position in response to movement of the piston The sleeve (90) and anvil (70) are releasably secured together so that the adapter tool can be removed from the housing as a unitary assembly Size changes can be accommodated by removing a first adapter tool of a given size and replacing it with a second adapter tool of a different size This changeover can be implemented without any disassembly or compromise of the hydraulic section The apparatus also provide a visual indication (22) that a swaging operation is completed by action of an indicator knob (140) that axially pops out of the back end of the housing at the end of a swaging operation

Backstepping based fuzzy logic control of active vehicle suspension systems

Abstract: In this paper, we present a backstepping based fuzzy logic (FL) scheme for the active control of vehicle suspension systems using the two-degrees of freedom or 1/4 car model. The full dynamics of a novel hydraulic strut are considered. The servo-valve dynamics are also included. A fuzzy logic system is used to estimate the nonlinear hydraulic strut dynamics. The backstepping fuzzy logic scheme is shown to give superior performance over passive suspension and active suspension control using conventional proportional-integral-derivative (PID) schemes. The FL system is adapted in such a way as to estimate online the unknown hydraulic dynamics and provide the backstepping loop with the desired servo-valve positioning so that the scheme becomes adaptive, guaranteeing bounded tracking errors and parameter estimates. A rigorous proof of stability and performance is given and a simulation example verifies performance. Unlike standard adaptive backstepping techniques, no linear-in-the-parameters assumptions are needed.

Hydraulic pump manifold

Abstract: A manifold (10) for a hydraulic system including a pump and accessories such as valves (42) and filters (88) as well as gauges in which the manifold is made part of the pump in fluid communication with the pump output to receive hydraulic fluid and deliver it to selected accessories and to return the fluid to the reservoir of the hydraulic system all with a minimum of hoses and couplings