Showing papers on "Hydraulic machinery published in 2011"

Handbook of Hydraulic Fluid Technology

Abstract: Fundamentals of Hydraulic Systems and Components, I. von Linsingen and V.J. De Negri Seals and Seal Compatibility, R.E. Zielinski and C.M.A. Chilson Physical Properties and their Determination, T. Kazama and G.E. Totten Fluid Viscosity and Viscosity Classification, B.G. Kinker Control and Management of Particle Contamination in Hydraulic Fluids, J.C. Fitch Lubrication Fundamentals, L.D. Wedeven and K.C. Ludema Hydraulic Fluid and System Standards, P.W. Michael and T.S. Wanke Biodegradable Hydraulic Fluids, I.-S. Rhee Fire-Resistance Testing Procedures and Standards of Hydraulic Fluids, J.V. Sherman Bench and Pump Testing Procedures, D. Smrdel and D.L. Clason Noise and Vibration of Fluid Power Systems, S.N.Y. Gerges, D. Nigel Johnston, and L. Zanetti Rocha Failure Analysis, A. Dias Petroleum Oil Hydraulic Fluids, J.R. Sander Emulsions, B.B. Filippini, J.J. Mullay, Y. Sun, and G.E. Totten Water-Glycol Hydraulic Fluids, J.V. Sherman Water Hydraulics, K.T. Koskinen and M.J. Vilenius Polyol Ester Fluids, P.R. Vettel Biobased and Biodegradable Hydraulic Oils, L.A.T. Honary Phosphate Ester Hydraulic Fluids, W.D. Phillips Polyalphaolefins and Other Synthetic Hydrocarbon Fluids, R.L. Shubkin, L.J. Gschwender, and C.E. Snyder, Jr. Food-Grade Hydraulic Fluids, S. Hamid

Control strategies for a wave energy converter connected to a hydraulic power take-off

Abstract: Among the various types of wave energy converters currently being developed, heaving point absorbers are one of the simplest and most promising concepts. A typical efficient energy conversion system for point absorbers is based on hydraulic power take-off (PTO) systems, consisting in a double-acting cylinder, a hydraulic motor and two or more accumulators. This paper presents a simple model of a heaving oscillating buoy extracting power by means of a hydraulic system. The hydrodynamic behaviour of the absorber is modelled through application of the linear water wave theory. Apart from the basic elements listed above, the model of the hydraulic system includes leakages and pressure losses and takes into account the compressibility of the fluid. Also, possible control accumulators are considered in order to improve the performance of the hydraulic system by means of properly controlled valves. Different control variables are analysed depending on the wave inputs considered in order to improve the power extraction of the converter. The results prove that it is possible to achieve a great enhancement of the power extraction with the implementation of these control strategies and that a possible combination of some of them might be beneficial for improved efficiency of the components.

Pressure Regulation in Nonlinear Hydraulic Networks by Positive and Quantized Controls

Abstract: We investigate an industrial case study of a system distributed over a network, namely, a large-scale hydraulic network which underlies a district heating system. The network comprises an arbitrarily large number of components (valves, pipes, and pumps). After introducing the model for this class of networks, we show how to achieve semiglobal practical pressure regulation at designated points of the network by proportional control laws which use local information only. In the analysis, the presence of positivity constraints on the actuators (centrifugal pumps) is explicitly taken into account. Furthermore, motivated by the need of transmitting the values taken by the control laws to the pumps of the network in order to distribute the control effort, we study the pressure regulation problem using quantized controllers. The findings are supported by experimental results.

A Fuzzy Expert System for Prioritizing Rehabilitation of Sewer Networks

Abstract: : Rehabilitation of sewer networks is a huge and very costly global problem that has often been treated on a crisis-based approach. The development of a rehabilitation program requires models and tools for assessing the condition and performance of sewers. The original contribution of this study is the development of a ranking scheme for sewer rehabilitation priorities. A fuzzy expert system was applied with inputs from a combined assessment of hydraulic, structural performance and potential failure consequences. The fuzzy structural system computes the global structural performance index for each pipe using internal condition, surrounding condition, and site vulnerability (SV) as inputs. The fuzzy hydraulic system uses hydraulic performance index (HPI), hydraulic performance impact, and SV to compute the global HPI. Finally, the fuzzy global system uses all these factors to compute the global performance index for each pipe. This methodology was successfully applied to the sewer system of the City of Laval in Canada. The results show how the fuzzy inference system may be used to establish rehabilitation priorities for each pipe section. The fuzzy expert system provides more realistic results than the intuitive approaches that use structural and hydraulic performance maximum and mean.

Electric energy recovery system for a hydraulic forklift - theoretical and experimental evaluation

Abstract: Energy efficiency has become a major research issue in all fields of engineering. As electrical drives have fast torque response capability and high controllability, they are penetrating new fields of engineering. Opportunities of utilising electric servo drives in the control of hydraulic lifting systems and enabling energy recovery in them are studied. In this study, the control of the hydraulic lifting and lowering system is carried out directly by an electric-servomotor-driven hydraulic machine. The efficiencies of the experimental drive system and its components are determined. At maximum, 66% of the potential energy was recovered in the low-power drive and improvements could still be achieved.

System and method for controlling power in machine having electric and/or hydraulic devices

Abstract: Disclosed is a system for controlling power in a machine. The system includes a controller configured to determine a level of power to be provided or consumed by at least one of an electric device and a hydraulic device based on request signals, operation signals, and a control strategy for controlling at least one of electric power and hydraulic power for the machine, and provide control signals for controlling operation of the at least one device. The control strategy includes a subsystem control and a supervisory control. The subsystem control includes at least one of electric and hydraulic subsystem controls for controlling operation of at least one of an electric device and a hydraulic device. The subsystem control is configured to provide range signals indicative of at least one of a range of acceptable electric power levels and a range of acceptable hydraulic power levels, and the supervisory control is configured to determine the control signals.

Implementation and Analysis of a Repetitive Controller for an Electro-Hydraulic Engine Valve System

Abstract: Variable valve actuation plays an important role in modern engine design. Fuel economy, emissions, and power output can be improved through appropriately varying valve lift and timing. One means of independently and continuously adjusting these valve profile parameters is with an electro-hydraulic valve system (EHVS). However, with an EHVS, it is very difficult to achieve the same level of accurate position control that a mechanical cam provides. In particular, the response time delay and the nonlinear dynamics of the hydraulic system can lead to error in valve position control. The paper first describes the identification method used to obtain a mathematical model of the EHVS. Based on the model, two linear feedback controllers are developed and compared. To further improve the tracking performance, a repetitive feed-forward controller is added to augment the feedback controller and the root mean square tracking error is improved to under 40 μ m. Stability and steady-state tracking error variance analyses complete the mathematical framework of this work.

Hydraulic control system having energy recovery

Abstract: An energy recovery retrofit kit for a hydraulic control system is disclosed. The energy recover retrofit kit may have a first accumulator and a second accumulator. The energy recover retrofit kit may also have a recovery valve block fluidly connectable between an existing pump and an existing motor of the hydraulic system. The recovery valve block may be configured to selectively fluidly communicate the first and second accumulators with the existing motor.

Black and Gray-Box Identification of a Hydraulic Pumping System

Abstract: The use of auxiliary information during the identification of nonlinear systems can be handled in different ways and at different levels. In this brief, static information of a 15 kW hydraulic pumping system is used as a priori knowledge in the parameters estimation of polynomial models which are compared to polynomial and neural models obtained by black-box techniques. The aim is to find models with good performance in both transient and steady-state regimes. This brief presents a novel bi-objective problem that uses free-run simulation and a new decision-maker. The optimization problem is solved using a genetic algorithm. Compared with other techniques, the proposed approach can lead to models with better dynamic and static performance.

Heterogeneous aquifer characterization from ground-penetrating radar tomography and borehole hydrogeophysical data using nonlinear Bayesian simulations

Abstract: It is known that the heterogeneity of hydraulic conductivity drives the groundwater flow and the transport of contaminants. However, in conventional characterization methods, the lack of densely sampled hydrological data does not permit us to describe the aquifer heterogeneity at an appropriate scale. In this study, we integrate ground-penetrating radar (GPR) tomographic data with hydraulic conductivity logs to estimate the hydraulic conductivity of a heterogeneous unconsolidated aquifer at a decimetric scale between two boreholes. The integration of these different data sets is achieved using a nonlinear Bayesian simulation algorithm. The prior hydraulic conductivity distribution is estimated, under Gaussian hypothesis, by simple kriging of the hydraulic well data. The likelihood of hydraulic conductivity given the relative permittivity and the electrical conductivity functions is obtained from a kernel probability density function estimator that describes the in-situ relationship between the electric and the hydraulic properties measured along boreholes. The proposed method is tested on a synthetic heterogeneous model of permeability to validate the methodology. We show that permeability realizations obtained from the proposed algorithm present a higher correlation with the synthetic model than other classical simulation methods. The method is then applied on data acquired over an unconsolidated aquifer located in Saint-Lambert-de-Lauzon, Quebec, Canada. The data set consists of measurements from (i) GPR crosshole acquisition, (ii) cone penetration testing with pressure measurement combined with soil moisture resistivity, and (iii) a borehole electromagnetic flowmeter. By using the presented Bayesian approach, we generated multiple hydraulic conductivity realizations that are in good agreement with the hydrogeological model of the area.

Micro-hydraulic structure for high performance bio-mimetic air flow sensor arrays

Abstract: Here we introduce a novel micro-hydraulic structure that can significantly improve performance of many MEMS devices. Using this structure we fabricate and test a new type of low-power, accurate and robust flow sensor in which a hair-like appendage is used to translate flow into hydraulic pressure. This pressure is hydraulically amplified and sensed with a capacitance that is integrated with the micro-hydraulic system. The air flow sensor can detect flow speeds ranging from zero to 10 m.s−1 with a resolution of 1 cm.s−1 in the low flow regime and a predicted minimum detectable flow of 3 mm.s−1.

Electric-drive-based control and electric energy regeneration in a hydraulic system

Abstract: Tatiana Minav Electric-drive-based control and electric energy regeneration in a hydraulic system Over the recent years, development in mobile working machines has concentrated on reducing emissions owing to the tightening rules and needs to improve energy utilization and reduce power losses. This study focuses on energy utilization and regeneration in an electro-hydraulic forklift, which is a lifting equipment application. The study starts from the modelling and simulation of a hydraulic forklift. The energy regeneration from the potential energy of the load was studied. Also a flow-based electric motor speed control was suggested in this thesis instead of the throttle control method or the variable displacement pump control. Topics related to further development in the future are discussed. Finally, a summary and conclusions are presented. Lappeenranta, June 23, 2011 150 p. Acta Universitatis Lappeenrantaensis 436 Diss. Lappeenranta University of Technology ISBN 978-952-265-103-7, ISBN 978-952-265-104-4 (PDF) ISSN 1456-4491

Systems and methods for optimizing thermal efficiency of a compressed air energy storage system

Abstract: Systems, methods and devices for optimizing thermal efficiency within a gas compression system are described herein. In some embodiments, a device can include a first hydraulic cylinder, a second hydraulic cylinder, and a hydraulic actuator. The first hydraulic cylinder has a first working piston disposed therein for reciprocating movement in the first hydraulic cylinder and which divides the first hydraulic cylinder into a first hydraulic chamber and a second hydraulic chamber. The second hydraulic cylinder has a second working piston disposed therein for reciprocating movement in the second hydraulic cylinder and which divides the second hydraulic cylinder into a third hydraulic chamber and a fourth hydraulic chamber. The hydraulic actuator can be coupled to the first or second working piston, and is operable to move the first and second working pistons in a first direction and a second direction such that volume in the hydraulic chambers are reduced accordingly.

A floating type wave power generation system

Abstract: A floating type wave power generation system is characterized in that the system consists of eight sets of lever-type floating bodies and a hydraulic energy accumulation converter with the hydraulic pump function. On a floating workbench 7, eight sets of levers 2 and a floating body 1 are connected through supporting hinge bearers 10 and 11; in this way, the highly undulating displacement caused by waves can be converted to relatively lesser displacement of a piston rod 4, and the minor force that the floating body bears can be converted through the lever to the major force on the piston rod. The piston rod drives a hydraulic tank 3 to switch and transmit the hydraulic energy through a connecting oil pipe5, a high-pressure oil pipe6, a hydraulic oil tank and four no-return valves of each set to a hydraulic motor in a hydraulic power generation control chamber 9; in this way the generator is driven to work. The present system can absorb, convert and accumulate the intermittent unstable wave energy in a highly effective way and can buffer the destructive effect of waves. The floating platform can be suitable to different marine space by adjusting the length of an anchor chain 8. And in various sea conditions, kinetic energy and potential energy possessed by waves in the sea surface can be converted and accumulated as hydraulic mechanical energy by utilization of the wave drop; thus the generator is driven to unremittingly provide electric power.

Parallel control for electro-hydraulic load simulator using online self tuning fuzzy PID technique†

Abstract: Hydraulic power systems have greater flexibility and can produce more power than mechanical and electrical systems of equal size. The aim of this paper is to describe results derived from an experimental study on a power hydraulic testing machine with hybrid force and position control. The paper includes the description and fabrication of this novel testing system, named electro-hydraulic load simulator (EHLS), for conducting a performance and stability test in a bench system where force or position control is important. In order to improve the control performance of the loading system and to eliminate or reduce noise, a parallel force and position control strategy using the proportional integral derivative (PID) control method, an online self-tuning fuzzy-neural mechanism, and system identification techniques are also presented in this paper. Experiments are carried out to evaluate the effectiveness of the proposed parallel force and position control method applied to the EHLS system.

Self-tuning fuzzy PID controller for electro-hydraulic cylinder

Abstract: Hydraulic systems are widely used in industrial applications. This is due to its high speed of response with fast start, stop and speed reversal possible. The torque to inertia ratio is also large with resulting high acceleration capability. The nonlinear properties of hydraulic cylinder make the position tracking control design challenging. This paper presents the development and implementation of self-tuning fuzzy PID controller in controlling the position variation of electro-hydraulic actuator. The hydraulic system mathematical model is approximated using system identification technique. The simulation studies were done using Matlab Simulink environment. The output performance was compared with the design using pole-placement controller. The roots mean squared error for both techniques showed that self-tuning Fuzzy PID produced better result compared to using pole-placement controller.

Controls of hydraulic wind power transfer

Abstract: The energy of wind can be transferred to the generator by employing a gearbox or through an intermediate medium such as hydraulic fluids. In this method, a high-pressure hydraulic system is utilized to transfer the energy produced from a wind turbine to a central generator. The speed control of wind driven hydraulic machinery is challenging, since the intermittent nature of wind imposes the fluctuation on the wind power generation and consequently varies the frequency of voltage. On the other hand, as the load of the generators increases, the frequency of the voltage drops. Therefore, hydraulically connected wind turbine and generator need to be controlled to maintain the frequency and compensate for the power demands. This paper introduces a closed loop gain scheduling flow control technique to maintain a constant frequency at the wind turbine generator. The governing equations of the renewable energy transfer system are derived and used to design the control system. The mathematical model is verified with a detailed model built using the SimHydraulics toolbox of MATLAB. The speed control profile obtained from a gain scheduling PI controller demonstrates a high performance speed regulation. The simulation results demonstrate the effectiveness of both the proposed model and the control technique.

System integration technology for dynamic soft reduction of continuously-cast billet

Abstract: A system integration technology for dynamic soft reduction of a continuously-cast billet belongs to the metallurgical technology field, comprises a dynamic soft reduction and dynamic secondary cooling water distribution software model, an electric automation control system, a hydraulic system and a mechanical device system, etc., and has significant effects on reducing or eliminating internal defects of a cast billet such as center porosity, segregation, etc., and improving the product quality. The dynamic soft reduction and dynamic secondary cooling water distribution two-stage control modelcan adapt to different operating conditions to carry out thermal tracking on a temperature field of the cast billet real timely and accurately, calculate the soft reduction range and the rolling reduction distribution, and set a roll gap value and a secondary cooling water amount dynamically; a first stage automation system can complete the on-site data gathering, process loop control, order control of the electric equipment, surveillance of the running operation of equipment, alarming, etc; the hydraulic system is responsible for uplifting and drop of a straightening machine via a proportional valve, and controls the rolling reduction by employing a displacement transducer to detect and feedback the travel of an oil cylinder; and the straightening machine employs a memorial archway type frame, and is equipped with a drive roller, a driven roller and a hydraulic elevating gear. Therefore, the remote control of the roll gap is realized, with control precision up to 0.1mm.

Hybrid of simulated annealing and SVM for hydraulic valve characteristics prediction

Abstract: Accurate prediction for the synthesis characteristics of hydraulic valve in industrial production plays an important role in decreasing the repair rate and the reject rate of the product. Recently, Support Vector Machine (SVM) as a highly effective mean of system modeling has been widely used for predicting. However, the important problem is how to choose the reasonable input parameters for SVM. In this paper, a hybrid prediction method (SA-SVM for short) is proposed by using simulated annealing (SA) and SVM to predict synthesis characteristics of the hydraulic valve, where SA is used to optimize the input parameters of SVM based prediction model. To validate the proposed prediction method, a specific hydraulic valve production is selected as a case study. The prediction results show that the proposed prediction method is applicable to forecast the synthesis characteristics of hydraulic valve and with higher accuracy. Comparing with Adaptive Neuro-Fuzzy Inference System (ANFIS) and Artificial Neural Networks (ANN) are also made.

Analysis of Pump-Turbine S Instability and Reverse Waterhammer Incidents in Hydropower Systems

Abstract: Hydraulic systems continually experience dynamic transients or oscillations which threaten the hydroelectric plant from extreme water hammer pressures or resonance. In particular, the minimum pressure variations downstream of the turbine runner during the load rejection or other events may cause dangerous water column separation and subsequent rejoinder. Water column separation can be easily observed from the measurements of site transient tests, and has indeed caused serious historical damages to the machine and water conveyance system. Several technical issues regarding water column separation in draft tubes, including S instability of turbine characteristic curves, numerical instability and uncertainty of computer programs, are discussed here through case studies and available model and site test data. Catastrophic accidents experienced at a Kaplan turbine and in a long tailrace tunnel project, as well as other troubles detected in a more timely fashion, are revisited in order to demonstrate the severity of reverse water hammer. However, as there is no simple design solutions for such complex systems, this paper emphasizes that the design of hydraulic systems is always difficult, difficulties that are compounded when the phenomena in question are non-linear (water hammer), dynamic (involving wave interaction and complex devices of turbines, controls, and electrical systems), andmore » non-monotonic (severity of response is seldom simply connected to severity of load as with vibrations and resonance, and the complexity of transient loads), and thus may lead to high economic and safety challenges and consequences.« less

Stochastic Analysis of Water Hammer and Applications in Reliability-Based Structural Design for Hydro Turbine Penstocks

Abstract: The randomness of transient events, and the variability of its associated dependencies, ensures that water hammer and surges in a pressurized pipe system are inherently stochastic. To improve reliability-based structural design, a stochastic transient model is developed for water conveyance systems in hydropower plants. The statistical characteristics of key factors in boundary conditions, initial states, and hydraulic system parameters are analyzed on the basis of a large record of observed data from hydro plants in China; the probability distributions of annual maximum water hammer pressures are then simulated by using a Monte Carlo method and verified with an analytical probabilistic model for a simplified pipe system. The key loading characteristics (annual occurrence, sustaining period, and probability distribution) are introduced and discussed. By using an example of penstock structural design, it is shown that the total water hammer pressure should be split into two individual random variable loads—the steady/static pressure and the water hammer pressure rise during transients—and that different partial load factors should be applied to individual loads to reflect specific physical and stochastic features. Particularly, the normative load (usually the unfavorable value at a 95-percentage level) for steady/static hydraulic pressure should be taken from the probability distribution of its maximum values over a pipe’s design life, whereas for the water hammer pressure rise, as the second variable load, the probability distribution of its annual maximum values determines its normative load.

Aircraft actuator hydraulic system

Abstract: A first actuator drives a control surface by being operated by supply of pressure oil from a first aircraft central hydraulic power source including a first aircraft central hydraulic pump. A second actuator drives the control surface by being operated by supply of pressure oil from a second aircraft central hydraulic power source including a second aircraft central hydraulic pump. A backup hydraulic pump is installed inside a wing of the aircraft and is provided so as to be able to supply pressure oil to the first actuator when a loss or degradation in a function of at least one of the first aircraft central hydraulic power source and the second aircraft central hydraulic power source occurs. A maximum discharge pressure of the backup hydraulic pump is set to be greater than maximum discharge pressures of the first aircraft central hydraulic pump and the second aircraft central hydraulic pump.

Movable arm flow re-generation system with potential energy recovery device for excavator

Abstract: The invention discloses a movable arm flow re-generation system with a potential energy recovery device for an excavator, and belongs to the technical field of engineering mechanical equipment. The system comprises a movable arm hydraulic cylinder, a three-position four-way servo valve, a controller, an overflow valve, an electromagnetic flow valve, a one-way valve, a variable output pump, an oil tank and an engine; the controller is electrically connected with the servo valve, the electromagnetic flow valve and the variable output pump; the three-position four-way servo valve is sequentially connected with a reversing valve and a hydraulic motor; the hydraulic motor is axially connected with a power generator; an output end of the power generator is electrically connected with a super capacitor; the outlet pressure of the hydraulic motor is controlled by the electromagnetic flow valve through the one-way valve of the motor; the reversing valve is connected with the oil tank; and the controller is electrically connected with the reversing valve, the power generator and the hydraulic motor. By the system, the optimal energy-saving state of the excavator can be realized during the falling of a movable arm, the energy consumption of the hydraulic system is reduced, the utilization ratio of the energy is improved, and the service life of the excavator is prolonged.

Hybrid power system architecture for an aircraft

Abstract: A hybrid power distribution system for an aircraft generates hydraulic power from one of a plurality of power sources based on which power source provides energy most efficiently. Power sources includes an electric power distribution bus that distributes electrical energy onboard the aircraft, a pneumatic distribution channel that distributes pneumatic energy onboard the aircraft, and mechanical power provided by one or more engines associated with the aircraft.

Design of the Microfluidic Chip of Oil Detection

Abstract: Wear debris in hydraulic oil causes most of the faults of hydraulic system and is also an important information carrier, so it is essential to check the condition of wear debris in hydraulic oil. On the basis of inductive principle and microfluidic chip technology, the design of a microfluidic chip of oil detection is presented in this paper. the relation between coil geometry parameters and inductive change of planar inductor are analyzed through the related experimental statistics, the result being that when the ferrous metallic particle flows through planar inductor, the measured inductance variation increases with the number of turns and decreases with the coil line width.

An experimental study and finite element analysis for finding leakage path in high pressure hose assembly

Abstract: High pressure power steering hoses used to steer vehicles supply hydraulic power generated by a hydraulic pump driven by engine. The life of high pressure hoses is affected by vibration and heat coming from the engine. The failure of high pressure power steering hoses is caused by leakage which occurs from fittings. This can be verified by analysis and observation through cutting the hose assembly to check leakage path. Through the completion of an experimental study, it was found that leakage [main failure mode] was the result of sharp corners of the sleeve damaging the outer rubber layer through constant movement. Although, the essential reason for leakage is the hardening of the rubber after a long period of use. The leakage phenomenon referred to above was verified by the reappearance of fluorescent material coming from the space between the nipple and the inner rubber—and the space between the reinforced material and the outer rubber. The goals of this study are the analysis of stress and strain distribution during the swaging process. Additional goals include determining where the stress concentration occurs, and proposing improvement points which include the shapes of the sleeve and nipple of the high pressure hose assembly as determined by finite element method.