Hydraulic Valve Research Articles

Dynamic characteristics analysis of a hydraulic valve by FEM and CFD method

The dynamic characteristic of the flood valve is an important index to ensure its safety and reliability. In this paper, CFD computational fluid dynamics (CFD) method is used to model and simulate the three-dimensional unsteady internal flow field of the valve during its working process, so as to obtain the dynamic distribution of the internal flow field parameters of the valve under specific working conditions. The modal analysis of the valve body is carried out to provide a calculation method and data support for the evaluation of the vibration and noise level during the operation of the valve.

Modelling and Validation of Cavitating Orifice Flow in Hydraulic Systems

Cavitation can occur at the inlet of hydraulic pumps or in hydraulic valves; this phenomenon should be always avoided because it can generate abnormal wear and noise in fluid power components. Numerical modeling of the cavitation is widely used in research, and it allows the regions where it occurs more to be predicted. For this reason, two different approaches to the study of gas and vapor cavitation were presented in this paper. In particular, a model was developed using the computational fluid dynamics (CFD) method with particular attention to the dynamic modeling of both gaseous and vapor cavitation. A further lumped parameter model was made, where the fluid density varies as the pressure decreases due to the release of air and the formation of vapor. Furthermore, the lumped parameter model highlights the need to also know the speed of sound in the vena contracta, since it is essential for the correct calculation of the mass flow during vaporization. A test bench for the study of cavitation with an orifice was set up; cavitation was induced by increasing the speed of the fluid on the restricted section thanks to a pump located downstream of the orifice. The experimental data were compared with those predicted by CFD and lumped parameter models.

Experimental Methods for Measuring the Viscous Friction Coefficient in Hydraulic Spool Valves

In hydraulic components, nonlinearities are responsible for critical behaviors that make it difficult to realize a reliable mathematical model for numerical simulation. With particular reference to hydraulic spool valves, the viscous friction coefficient between the sliding and the fixed body is an unknown parameter that is normally set a posteriori in order to obtain a good agreement with the experimental data. In this paper, two different methodologies to characterize experimentally the viscous friction coefficient in a hydraulic component with spool are presented. The two approaches are significantly different and are both based on experimental tests; they were developed in two distinct laboratories in different periods of time and applied to the same flow compensator of a pump displacement control. One of the procedures was carried out at the Fluid Power Research Laboratory of the Politecnico di Torino, while the other approach was developed at the University of Parma. Both the proposed methods reached similar outcomes; moreover, neither method requires the installation of a spool displacement transducer that can significantly affect the results.

Efficient oscillation detection for verification of mechatronic closed-loop systems using search-based testing

In mechatronic system design, the systematic early-stage verification in simulation environments is a crucial aspect. In particular, the development of highly sophisticated and well performing controllers requires complementary testing by extensive simulations. The assessment and evaluation of the control strategy and its tuning is ideally carried out by specialists and is usually very time consuming. Due to time constraints, often only the nominal configuration and a limited number of other configurations are considered in the simulation-based analysis of the closed-loop system. To cover a more comprehensive set of test cases and speed up the analysis, assistive and automated tools are essential. This paper proposes a method to systematically search for oscillations in closed-loop mechatronic systems, which, in most cases, indicate a poor control performance or even an unstable system behavior. Although oscillation detection methods are very well established in the process industry, these methods do not directly apply to mechatronic systems where frequent changes of the operating points and tracking of fast trajectories have to be taken into account. A recently proposed method which can cope with these challenges uses the Empirical Mode Decomposition (EMD) combined with an assessment of the decomposed modes. This is the basis for the construction of a normalized and continuous oscillation index, which provides a suitable measure for the oscillation strength. The performance of the selected EMD approach compared to other state-of-the-art concepts is illustrated by measurement data of a hydraulic valve. The introduced oscillation index serves as an objective function for a Search-based Testing (SbT) approach to systematically select those parameter combinations which yield a worst-case scenario for the closed-loop system. The high potential of the combination of SbT with an oscillation-based objective function for the automated verification of closed-loop mechatronic systems is demonstrated for the example of a goods lift.

Measurement and Evaluation of Functional and Operational Coefficients of Hydraulic Solenoid Valve Prototypes Used for Variable Valve Timing Control in Combustion Engines

Abstract This paper describes the engineering structure and functions of a typical solenoid valve used in hydraulic mechanisms that are based on variable camshaft timing (VCT). The main operating parameters and functional utility coefficients of hydraulic solenoid valves have been defined. Tests of 10 reference and 10 prototype valves were run on a test stand for a comparative assessment of both engineering concepts based on Welch and Mann–Whitney statistical tests of the mean values of designated coefficients. The studies identified differences between both designs, and the obtained research material was used as an input to improve the performance of the engineered concept. To perform a final evaluation of the effects that arise as a result of changes introduced to some functional–operational coefficients, additional tests are required to be run on an engine testbed. The applied test methodology may then be used for control and verification tests of the valves, which can further be used in VCT technology.

Research on the dynamic characteristics of water hydraulic servo valves considering the influence of steady flow force

The International Thermonuclear Experimental Reactor remote-handling (ITER-RH) system powered by water hydraulics is a vision of the future. The 2D servo valve is a new type of servo valve, maybe suitable for the ITER-RH system. It has many advantages, including its fast response and strong anti-pollution ability. However, steady flow force is currently considered to be one factor that impacts the dynamic characteristics of servo valves. In this study, the influence of steady flow force on the dynamic characteristics was analyzed, and the structure was optimized accordingly. A mathematical model of the servo valve was built using theoretical analysis and numerical simulation. Results indicated that the amplitude bandwidth of the 2D water hydraulic servo valve was 169 Hz without considering the steady flow force, and it decreased to 162 Hz when the steady flow force was considered. Furthermore, a newly designed valve sleeve, to compensate for the axial steady flow force, was proposed by changing the angle of the inlet port designed in the valve sleeve to the spool axis. The maximum compensation capacity of the axial steady flow force was 35%, and the best angle of the inclined holes was approximately 120°. The optimized amplitude bandwidth of the 2D servo valve was 167 Hz. The results demonstrate that the optimized valve sleeve improved the dynamic response of the 2D servo valve.

Investigation on the Modeling and Dynamic Characteristics of a Novel Hydraulic Proportional Valve Driven by a Voice Coil Motor

As the key control component of the water hydraulic systems, the water hydraulic proportional valve has a significant influence on the control performance of the systems. Due to the poor viscosity and lubricity of water, the valve spool resistance is large and non-linear. In this study, a novel fast-response water hydraulic proportional valve is presented. The actuator of the valve adopts a voice coil motor (VCM), which has the advantages of fast response, high control precision and small volume. In order to realize the fast control of the valve, a lever amplifier is designed to obtain enough actuation force. A detailed and precise non-linear mathematical model of the valve considering both the valve’s structural parameters and VCM electromagnetic characteristics is developed. A comprehensive performance simulation analysis has been carried out, mainly divided into an electromagnetic simulation, an analysis of the characteristics of the lever magnifier, and a dynamic performance simulation of the valve. The simulation results show that the adjusting time is about 28ms, and the maximum overshoot is about 5 %. The step response rise time is about 15 ms. The test rig of the valve and VCM have been built. The test results of the prototype show that the optimal stroke range of VCM is 4 mm to 15 mm. The maximum overshoot of the valve is around 10 %; the adjusting time is about 30 ms in the opening process and 35 ms in the closing process. The test results prove that the valve has good static and dynamic control performance.

Monitoring the Degradation in the Switching Behavior of a Hydraulic Valve Using Recurrence Quantification Analysis and Fractal Dimensions

Abstract Valves are crucial components of a hydraulic system that enable reliable fluid management. Hydraulic valves actuated by a solenoid are prone to degradation in their switching behavior, which may induce undesirable fluctuations in the fluid pressure and flow rate, thereby impairing the system performance and limiting its predictability and reliability. Therefore, it is imperative to monitor the switching behavior of solenoid-actuated hydraulic valves. First, recurrence quantification analysis (RQA) has been applied to the experimental flow signals from a hydraulic circuit to understand the complex switching behavior of the valve. Using RQA, the monotonicity of six recurrence-based parameters has been assessed. In addition, two more nonlinear features, namely, Higuchi and Katz fractal dimensions have been extracted from the flow signals. Based on these eight features (six RQA-derived features and two nonlinear features) a feature matrix is formulated. Second, in a parallel approach, eight different statistical features are extracted from the flow signal to construct another feature matrix. Subsequently, different machine learning methods namely Ensemble learning, K-Nearest Neighbor (KNN), and support vector machine (SVM) have been trained on these two feature sets to predict the valve switching characteristics. A comparison between two feature sets shows that ensemble learning gives better prediction accuracy (99.95% versus 92.2% using statistical features) when fed with RQA features combined with fractal dimensions. Therefore, this study demonstrates that by utilizing the recurrence plots and machine learning techniques on the flow rate signals, the degradation in the switching behavior of hydraulic valves can be monitored effectively, with a high-prediction accuracy.

An Optimized E/CRC Erosion Model of Round Particles for Hydraulic Spool Valves With Euler–Lagrange Two-Phase Simulation

Solid particles mixed in the oil cause erosion of hydraulic spool valves, and these valves may fail in severe erosion. In this article, with the help of the Euler–Lagrange solver, a numerical model of the solid–liquid two-phase flow is established for the spool valves, in which the standard k-ε model is used for the turbulent flow. With a comparison of seven different erosion models, the E/CRC erosion model is the closest one to the experiment data. Based on the numerical model and the experiment data, an optimized E/CRC erosion model with a new impact angle function for complete round particles is proposed for the spool valves. It is observed that there is better agreement between the optimized model and the experimental values. In addition, the relationships between the erosion rate and the main influencing factors are revealed, including the particle size, particle concentration, differential pressure, flow direction, spool opening, and oil viscosity.

Design and performance analysis of hydraulic switching valve driven by magnetic shape memory alloy

In this paper, the hydraulic switching valve is designed and its dynamic performance is investigated through proposing a fast response actuator with magnetic shape memory alloy (MSMA) to drive the valve. MSMA actuator with spring return is designed and a double-layered coil is constructed to achieve compactness of electromagnetic case. The dynamic characteristics of the MSMA actuator are analyzed and the step response characteristics is tested. Hydraulic switching valve with MSMA actuator is designed with poppet type. Pressure and velocity field in the flow channel under different valve opening and different inlet and outlet pressure differences are analyzed in COMSOL Multiphysics software. The dynamics of the valve poppet during opening and closing process is modeled mathematically, and simulation analysis are conducted in AMESim software to analyze the response of valve under step and square wave signals. The step response of output flow rate and pressure-flow characteristic under different operating conditions are obtained through experiment. The results show that the MSMA based valve can achieve fast response with opening time of 5 ms at the pressure difference of 1 MPa, providing a theoretical support for the development of hydraulic switching valve with high performance actuator driven by MSMA.

A Note on Leakage Jet Forces: Application in the Modelling of Digital Twins of Hydraulic Valves

The proper modelling of fluid flow through annular gaps is of great interest in leakage calculations for many applications in fluid power technology. However, while detailed numerical simulations are certainly possible, they are very time consuming, in various cases prone to numerical instabilities and may not even include all physically relevant effects. This is an issue especially in system simulations, where a large set of computations is needed in order to prepare the lookup-tables for the required input fields. In this work, an analytical approximation for the shear force, which is induced by viscous flow between two eccentric cylinders, is presented. This relation, and its derivation, mimics and enhances the well-known Piercy-relation for the corresponding volume flow that is utilized in state-of-the-art system simulation tools. To determine its range of validity, the analytical relation for the shear force is compared to 3D-simulations. Additionally, an application of this approximation for creating digital twins of hydraulic valves is also discussed in this work.

Perawatan dan Perbaikan Sistem Hidrolik pada Dumping Dump Truck Mitsubishi Fuso 190Ps

Sistem hidrolik pada dump truck yang terdiri dari beberapa komponen memerlukan tindakan perawatan terencana, agar sistem hidrolik dapat berfungsi secara optimal. Tujuan penulisan adalah untuk dapat melakukan analisa kerusakan dan dapat melakukan tindakan perbaikan dengan tepat dan benar. Metode penganalisaan dalam analisa perawatan dan perbaikan sistem hidrolik ini ialah dengan menggunakan beberapa pertanyaan, yaitu apa, kenapa, dimana, dan bagaimana. Komponen utama sistem hidrolik dump truck yang memerlukan perawatan adalah seperti tangki hidrolik, pompa, katup, aktuator, filtrasi dan slang hidrolik, adapun penyebab utama kerusakan dari komponen sistem hidrolik tersebut adalah karena kebersihan oli hidrolik yang buruk, kontaminasi dalam sistem, dan kelebihan beban(over load). Untuk mengatasi kerusakan yang terjadi adalah dengan jalan menerapkan manajemen perawatan dan perbaikan yang benar, terencana dan sesuai SOP.

Fault diagnosis in a hydraulic directional valve using a two-stage multi-sensor information fusion

As it is usually operating in bad working conditions and subjected to the severe interference from diverse paths, internal faults of the hydraulic valve are difficult to be detected using conventional hydraulic testing technology (such as relying on pressure sensors or flow sensors). Moreover, the information collected from a single sensor may not provide accurate diagnostic evidence or a complete description on faults of hydraulic valves, even though employing intelligent fault diagnosis methods. Therefore, a two-stage multi-sensor information fusion method is proposed, including the fault feature fusion and the decision-making information fusion. The aim is to realize the diagnosis on internal faults of hydraulic directional valves using the vibration signal analysis method instead of conventional hydraulic testing ones. The method is mainly divided into three steps. First, the noise reduction of the vibration information collected by multiple acceleration sensors is done using ensemble empirical mode decomposition (EEMD) and Teager-Kaiser energy operator (TEO), so that fault features are more obvious. Then, multi-class fault features including the severity and the location of the wear are extracted from the preprocessing signals to form the original feature set. Second, combined with feature ranking and subset selection based on euclidean distance (FRSSED) and maximum relevance minimum redundancy (mRMR) feature selection method, the statistical features extracted from multiple sensor signals are optimized to form the optimal feature subset. This is the first-level information fusion concerned with fault feature information fusion. In the third step, based on Dempster-Shafer (DS) evidence theory and convolutional neural network (CNN), decision-making information is fused (called second-level information fusion) to obtain the final diagnosis results. A hydraulic test bench is built to test different failure valves. Experimental results indicate that this method is effective in extracting the fault features from multi-sensor signals and detecting the fault states including severity and location of internal wear of the hydraulic valve.

INVESTIGATION OF THE INFLUENCE OF THE SPACING BETWEEN THE BORE OF THE THROTTLING SECTION OF THE SHUT-OFF AND CONTROL VALVES ON THE GENERATION OF THE HYDRODYNAMIC NOISE

When designing the throttle sections of the shut-off and control valves, consisting of groups of holes, the question arises about the choice of the distance between the axes of the spacings. The article presents a numerical simulation of the throttling section of a hydraulic valve using two working media: water and fluid PGV . The dependences of the jet lengths on the center-to-center distance are presented. An experimental study of the dependence of the hydrodynamic noise on the center distance between the spacings was also carried out.

Study of a measurement system and a method for determining the distance between the grooves of a hydraulic valve

Hydraulic valves are critical control components of hydraulic systems. To ensure hydraulic control systems are accurate, the distance between the grooves of hydraulic valves should be measured. This distance critically impacts how much oil is fed. In previous measurements, a coordinate-measuring machine or a universal tool microscope were applied. However, these two methods exhibited low measuring precision in terms of center eccentricity, incorrect initial position, boresight error, etc. In the present study, a high-precision non-contact automatic instrument is developed that solves chord length and uses a machine-vision technique to determine distance. Besides, an angle-compensation method is proposed to remedy the boresight error attributed to motion control in a closed-loop system. Moreover, an eccentricity-correction method is put forward to correct the angular error attributed to the eccentricity of the measurement system, enhancing measurement precision. As revealed by the experimental results, the maximum limit error of a single measurement is less than 3.3 μ, verifying the feasibility of the novel instrument.

Mechanism Operation for Changing the Rear Axle Clearance of a Universal Row-crop Tractor

The authors noted the disadvantages of the 3-wheel universal row-crop tractor. To eliminate them, LLC Design and Technological Center for Agricultural Engineering developed a 4-wheel universal row-crop tractor with variable ground clearance.(Research purpose) To determine the pressure change in the hydraulic system and the transfer time of the rear axle from one type of clearance to another.(Materials and methods) The authors showed that the rear axle clearance could be changed using a special mechanism - with minimal labor costs, without the use of lifting equipment and assembly and dismantling works. They explained that the mechanism was driven by a working hydraulic cylinder. The experiments were carried out on a prototype tractor with adjustable ground clearance, equipped with a separate-aggregate hinged system at an engine speed of 1200-2000 rpm (revolutions per minute). M10G2K oil was used in the hydraulic system, heating it to 65 degrees Celsius (at an ambient temperature of 33-35 degrees Celsius).(Results and discussion) The hydraulic system consisted of an NSh-32 hydraulic pump, a P80 hydraulic valve, two Ts50-200 working hydraulic cylinders, a double-acting hydraulic lock, a hydraulic tank, filters, hoses and high pressure pipes. At the inlet and outlet channels of the working hydraulic cylinders, which activated the mechanism for changing the rear axle clearance, hydraulic locks were installed, and diaphragm pressure sensors model SS302 from Sendor Sensor with a measurement range from 0 to 40 megapascals were placed along the hydraulic line connecting the hydraulic locks with the hydraulic valve.(Conclusions) The authors determined that the time for transferring the rear axle from low clearance to high was 2.2-4.4 seconds, and the pressure in the hydraulic system was 3.8-16.4 megapascals at an engine speed of 1300-2000 rpm. It was found that when transferring from high to low ground clearance, these indicators amounted to 1.0-1.4 seconds and 0.99-9.90 megapascals.

Common design structures and substitutable feature discovery in CAD databases

It has been widely reported that the reuse of previously created components, or features, in new engineering designs will improve the efficiency of a company’s product development process. Although the reuse of engineering components has established metrics and methodologies, the reuse of specific design features (e.g. stiffening ribs, hole patterns or lubrication grooves, etc.) has received less attention in the literature. Typically, researchers have reported approaches to partial design reuse that identify patterns predominately in terms of geometrically similar shapes (i.e. a set of features) whose elements are adjacent, cohesive, and decoupled from the overall form of a component.In contrast, this paper defines a common design structure (CDS) as collections of frequently occurring features (e.g. holes) with common parametric values (e.g. diameters) in a CAD database (irrespective of their locations or spatial connectivity between other features on a component). By exploiting the established data-mining technology of association rules and item-sets the authors show how CDSs can be efficiently computed for hundreds of 3D CAD models. A case study, with hole data extracted from a publicly available dataset of hydraulic valves, is presented to illustrate how item-sets associated with CDS can be computed and used to support predictive design by identifying potentially ‘substitutable features’ during an interactive design process. This is done using a combination of association rules and geometric compatibility checks to ensure the system’s suggestion are implementable. The use of the Kullback–Leibler divergence to assess the degree of similarity between components is identified as a crucial step in the process of identifying the “best” suggestions. The results illustrate how the prototype implementation successfully mines the CDSs and identifies substitutable hole features in a dataset of industrial valve designs.

Stomata: the holey grail of plant evolution

Stomata: the holey grail of plant evolution

Energy harvesting approach to utilize the dissipated energy during hydraulic active suspension operation with comfort oriented control scheme

Even though the active suspension provides enhancement in comfort and road-holding in addition to vehicle safety and handling, energy demand is one of the major problem in commercialization. Therefore, energy harvesting from the vehicle active suspension brings greater significance to the energy management and vehicle dynamics research. The consumption of more power occurs by hydraulic active suspension for the process of fluid actuation into chamber through the control valves and instantaneously significant amount of power is being dissipated by another chamber of the same actuator. Hence, this study propose a novel approach to harvest energy from the dissipating energy of active suspension through the control valve. In order to ensure the comfort and road-holding, model predictive control effort was provided to the hydraulic control valve. Dissipated fluid during the operation was directed to the hydraulic motor to generate the power and the influence of hydraulic power generation unit is being compensated by two new approaches. For the numerical simulation, active suspension integrated four wheel vehicle model was developed in AMESim and its control valve is controlled in Matlab co-simulation environment. The 1D mapped variable and constant resistance energy harvesting schemes provided the maximum RMS power of 1385.4 W & 1427.6 W in the D-class road at 28 m/s velocity. Also, the results of both proposed energy harvesting approaches showed that the comfort oriented characteristics of active suspension such as actuator effort, comfort and road-holding were not affected.

Cavitation Characteristics of Hydraulic Safety Valves for Coal Mine Water with Different Openings

Cavitation Characteristics of Hydraulic Safety Valves for Coal Mine Water with Different Openings