Hydraulic Valve Research Articles

Fast luffing control of flexible boom of mobile elevated work platform with uncertain control input gain

In this paper, the dynamic model between input electric signal of hydraulic valve and boom luffing angle is established, and luffing control of flexible boom of mobile elevated work platform (MEWP) is studied. The control input gain for the luffing motion of the MEWP is extremely difficult to solve and varies with boom length, work platform load, and luffing angle. For the variable control input gain, all low-order state quantities, rigid-flexible coupling quantity, and control input are included as the “total disturbance” to be observed. Based on the third-order linear tracking differentiator and the first-order ordinary differential linear equation, an active disturbance rejection controller without control input gain is proposed. With the bandwidth-based parameter settings, the controller only needs to adjust two parameters. As a comparison, this paper analyzes in detail the proposed controllers, the fixed input gain active disturbance rejection controller and the PID controller in terms of tracking error, overshoot, setting time, tracking stability, and robustness.

Electrical and mechanical data fusion for hydraulic valve leakage diagnosis

This paper describes a method for the identification of valves’ failure, with the final aim of creating a predictive maintenance architecture. After revising the scientific literature, we selected the electric current, the acoustic emission and the vibration signals as the most promising monitoring techniques. The processes of feature extraction and data fusion have been optimized to detect early symptoms of a failure. Performances of five different machine learning algorithms have been compared. Results, obtained in a specific case study, evidenced that a data fusion process based on vibration and current data, paired with a random forest model allowed a prediction accuracy and a Jaccard index close to 99%.

Erosion microscopic morphology and formation mechanism of hydraulic servo spool valve

This study investigates the microscopic morphology of a hydraulic servo spool valve caused by particle erosion. The microscopic morphology of spool working edges and solid particle characteristics in oil of a typical hydraulic servo system were experimentally studied. The formation mechanism was analyzed using dynamic impact calculation. The results reveal that the erosion micro-morphology of the spool working edge was mainly characterized by surface peeling, notches, grooves, and chamfers. The contour of the working edge was rounded. The average and variance of the radius of the old spool’s working edges were obviously higher than those of the new spool. The main distribution range of solid particle size in typical servo-hydraulic system oil was 5–50 μm, and the number of particles decreased sharply with an increase in particle size, up to 90.89%. The actual shape of particles was close to an ellipsoid with strong erosion destructive power. When a single solid particle collided with the working edge, a large amount of stress was generated at the collision center point, and the stress can reach 1500 MPa when the pressure differential at the valve orifice was 3.5 MPa. The working edges were subjected to cyclic stress of high-frequency particle pulses, resulting in fatigue erosion.

Experimental study on the correlation between erosion microstructure and performance degradation of hydraulic servo spool valve

Surface topography plays an important role in determining the performance of hydraulic components, which often leads to component failure. The dual nozzle electro-hydraulic servo valve is composed of torque motor, pilot nozzle flapper valve and servo spool valve, whereas the failure is at the level of servo spool valve. In more details, the degradation of the static characteristic parameters of the hydraulic servo valve, which is experimentally studied by artificially controlling the fillet radius of the spool working edges, is one of these failures. In addition, the microstructure characteristics of the MOOG J761 valve working edges and the circumferential distribution law of the fillet radius are obtained. The research shows that valve orifice erosion caused fillet on the working edges and increases the dispersion of the circumferential distribution. The erosion micromorphology of the working edge is mainly characterized by surface peeling, notches, grooves, and chamfers. The average and variance of the fillet of the spool working edge at the high-pressure oil exceed those of the working edge of the return oil. When the average fillet radius of the working edge increases by 2.71 times and the average fillet variance increases by 2.55 times, the maximum leakage increases by 5.08 times, the flow gain decreases, and the positive and negative flow gains are asymmetric, decreasing by 7.78% and 1.75%, respectively. The pressure gain decreases significantly by 40.30%. The relation between the microstructure of the orifice working edge and the performance degradation provides a new idea for the performance evaluation and manufacture of hydraulic spool servo valve.

Fault diagnosis of the hydraulic valve using a novel semi-supervised learning method based on multi-sensor information fusion

Hydraulic systems are usually applied in large and complex engineering fields. For hydraulic systems or components in operation, it is difficult to obtain fault data with fault labels due to the high engineering cost. Therefore, a semi-supervised learning (SSL) method based on multi-sensor information fusion is proposed to obtain valuable pseudo label data to diagnose faults of the hydraulic directional valve in operation. In this method, the classification model is trained from a small amount of data with fault labels, thus generating pseudo labels for a large amounts of unmarked data. The contribution of this article is that a multi-sensor fusion algorithm is designed to obtain pseudo labels with high confidence, and an adaptive threshold model similar to generative countermeasure network is designed to intelligently generate thresholds for selecting pseudo labels instead of human intervention. Theoretical and experimental results show that the multi-sensor information fusion algorithm can obtain high confidence pseudo tags, the adaptive threshold model can screen effective pseudo tag samples by generating appropriate thresholds for accelerating the convergence of the classification model. In the hydraulic valve fault diagnostic test, after five iterations, the average diagnosis accuracy of this method can reach 99.72% and 99.00% respectively for different types of hydraulic valves in different engineering fields. This provides a new idea for developing intelligent hydraulic directional valve with self fault diagnosis function.

Modeliranje i simulacija rada modulatora pritiska kod menjačkih prenosnika sa promenom stepena prenosa bez prekida toka snage

Introduction/purpose: The hydraulic buffering valve has the greatest influence on the dynamic characteristics of power-shift transmission. The hydraulic buffering valve is a transmission element that controls increase in pressure in friction assemblies during the gear shifting process. By choosing the optimal control of pressure increase during shifting, reduction of dynamic loads in gear transmissions and thermal loads in friction assemblies is achieved. Methods: The paper analyzes the principle of one of hydraulic buffering valve solutions as well as the influence of certain parameters on the control of pressure increase. After the analysis of the working principle of the hydraulic buffering valve, a simulation model was developed in the MATLAB/Simulink software package. Results: The results obtained using the simulation model were compared with the experimental results of the selected pressure modulator solution. The selected hydraulic buffering valve was developed as part of the development of a device for power-shift transmission. The simulation results showed a satisfactory match with the experimental results. Conclusion: The developed simulation model enables a relatively easy and quick change of the parameters of the hydraulic buffering valve as well as a possibility of a faster and better understanding of the influence of individual parameters on pressure increase during the gear shifting process.

Characteristics of Electrohydraulic Control System for Electromechanical Coupled Transmission of Plug in Hybrid Electric Vehicles

This study focuses on exploring the characteristics of the electromechanical coupling transmission electro-hydraulic control system of plug-in hybrid electric vehicles, and proposes corresponding optimization measures to improve the performance and economy of the vehicle, and reduce the impact on the environment. Firstly, we analyze the working mode of plug-in hybrid vehicles; then design the structure of electromechanical coupling with variable speed and the main components of the electro-hydraulic control system, including flow control system, cooling lubrication circuit, brake and shift control circuit, hydraulic valve and spring. Finally, we applied AMESim simulation software to analyze the response characteristics of each hydraulic valve and optimized the relevant parameters of the valve based on the simulation results. By establishing a dynamic simulation model for the electro-hydraulic control system, in-depth analysis is conducted on the pressure and flow response characteristics of the clutch under slope and step signal control.

Study on the sealing test method of hydraulic solenoid valve in nuclear power station

In order to improve the reliability of tripping solenoid valve and switching solenoid valve of steam turbine valve in nuclear power plant and reduce abnormal valve closing. According to the working principle of valves in nuclear power plant, this paper designs a kind of electromagnetic valve sealing test system, including test base, measurement and control system and hydraulic system. The detection system is an offline system. By simulating the real load condition of the steam turbine system, the tightness of the tripping solenoid valve and the switching solenoid valve is tested to improve the reliability of the solenoid valve. The actual application results show that the system operates stably and reliably, is simple to operate, has high detection efficiency and accuracy, and has good use effect.

Nonlinear Dynamics of Pilot-Operated Hydraulic Control Valves for Submersible Based on Improved Newmark- Integration Method

Nonlinear Dynamics of Pilot-Operated Hydraulic Control Valves for Submersible Based on Improved Newmark- Integration Method<i />

In-silico modelling of the impact of hypertension on the mean transvalvular gradients in aortic stenosis.

The influence of hypertension on the diagnostic assessment of aortic stenosis (AS) severity is unclear, yet clinically relevant. To clarify the effect of hypertension on transvalvular gradients, requires a better understanding of the impact that blood pressure change has on mean flow rate. Also, the effect of various degrees of AS severity, the valve geometry and intrinsic left ventricular contractile function (elastance) on this interaction, needs to be clarified. The current work aims to assess this interaction and the magnitude of these effects. A validated, zero-dimensional electro-hydraulic analogue computer model of the human cardiovascular circulatory system was generated. It was used to assess the impact of blood pressure changes on left ventricular pressure and transvalvular gradients at various flow rates, left ventricular elastances, a range of aortic valve areas and for different aortic valve morphologies. The magnitude of the impact of hypertension induced changes on the mean gradient (MG) is influenced by the mean flow rate, the AS severity, the hydraulic effective valve orifice area and the left ventricular elastance. Generally, for a given change in systemic arterial pressure, the impact on MG will be the most marked for lower flow rate states such as is expected in more severe degrees of AS, for worse intrinsic left ventricular (LV) contractility, shorter ejection times and lower end diastolic LV volumes. Given the above conditions, the magnitude of the effect will be more for a larger aortic sinus diameter, and also for a typical degenerative valve morphology compared to a typical rheumatic valve morphology. The interaction between hypertension and mean gradients in AS is complex. The current work places previous recommendations in perspective by quantifying the magnitude of the effect that the changes in blood pressure has on mean gradient in various pathophysiological states. The work creates a framework for the parameters that should be considered in future clinical research on the topic.

Investigation of thermal behavior and orifice flow characteristics of aeronautic hydraulic servo-proportional valve spool-sleeve structure with numerical simulations

In this study, the mechanical behavior under highest thermal conditions and flow characteristics of the hydraulic fluid of the servo-characterized proportional valve, which is one of the indispensable components of the aviation industry and used for hydraulic flow control, were investigated numerically. In the simulations, 50, 75 and 100 °C were selected as temperatures, and 0.2 mm, 0.6 mm and 1.2 mm spool stroke openings were used for hydrodynamic flow. Simulations were carried out for a pressure difference of 35 bar. As a result of the analysis, it was observed that there was no restriction in the movement of the spool-sleeve structure for a temperature of 75°C, excessive friction occurred in the spool-sleeve structure at 100°C and the movement was restricted. In addition, it can be said that hydraulic turbulences are effective in dispersing polluting particulate matter for all three spool strokes at a pressure difference of 35 bar.

Modelling and Experimental Verification of the Interaction in a Hydraulic Directional Control Valve Spool Pair

This study examined the impact of mechanical oscillation on a hydraulic directional control valve. Particular attention was paid to the oscillating movement of the spool of the hydraulic directional control valve resulting from this impact. Different models of fluid and mixed friction were considered. The models analysed accounted for the relative movement of the directional control valve body and the fact that it is kinematically excited by external mechanical oscillations. It was observed that the mixed friction model, where the frictional force is considered to be the sum of molecular forces acting in micro-areas of contact and drag forces in the fluid, was the best for describing the movement of the spool for a specific spool oscillation frequency. This model yielded significantly more consistency between the simulated and experimental results than the classic fluid friction model.

Simulation analysis and experimental research on mechanical properties of water hydraulic ball poppet valve

Simulation analysis and experimental research on mechanical properties of water hydraulic ball poppet valve

Analysis on the Corrosion of the Inner Cavity of the Christmas Tree Hydraulic Valve in a Well in Western China

In this paper, with the observing corrosion morphology of the inner cavity of the Christmas tree hydraulic valve and detecting the physical and chemical properties of the material (chemical composition, mechanical properties and metallographic structure),It is found that the main reason for the corrosion of the inner cavity of Yidong fan is that in the production process, due to improper heat treatment process, Cr element is accumulated in the metallographic structure of the hydraulic valve matrix, forming a grid like high Cr region, and the grid becomes a low Cr region, under the action of formation water containing CO2, the low Cr area is corroded, and large and deep corrosion pits are formed in the internal cavity of the hydraulic valve.

Application of the Methodology of Multi-Valued Logic Trees with Weighting Factors in the Optimization of a Proportional Valve

Hydraulic valves are used to determine the set values of hydraulic quantities (flow rate, pressure, or pressure difference) in a hydraulic system or its part. This is achieved through the appropriate throttling of the stream flowing through the valve, which is automatically set by the operator (e.g., opening the throttle valve). The procedures for determining its static and dynamic properties were described using the example of modeling a two-stage proportional relief valve. Subsequently, the importance of the design and operational parameters was determined using multi-valued logic trees. Modeling began with the determination of equations describing the flow and movement of moving parts in a valve. Based on the equations, a numerical model was then created, e.g., in the Matlab/Simulink environment (R2020b). The static characteristics were obtained as the result of a model analysis of slow changes in the flow rate through the valve. Various coefficients of logical products have not been taken into account in the separable and common minimization processes of multi-valued logic equation systems in any available literature. The results of the model tests can be used to optimize several types of hydraulic valve constructions.

CLAW FOR ROUND BALES

The claw for round bales is an attachment to the base machine of a front loader. This is used in agriculture for handling of big sized straw bales. Arms opening respectively, closing, are performed with different speeds to allow claws removal from bales stack without damaging the nearby bales. The strong construction ensures handling of big sized bales. The needed force during transport is provided by two hydraulic cylinders and hydraulic safety valve. For making the transport systems used in agriculture, it is useful to make computer aided simulations, to obtain some virtual models for such equipment. This paperwork presents how the claw for round bales handling can be designed, starting from needed parameters (bale size, bale weight, lifting capacity, etc.) and farmer’s requirements. We went through the stages of computer aided engineering taking into account various requirements of the farmers. The claw for bales handling is attached to a front loader or a tractor based upon the equipment fleet the farmers own. The parametric modeling of the claw type attachment for round bales was done by using NX 7.5 specialized software. This software uses powerful tools for modeling, allowing the use of the most efficient techniques for advanced modeling – from explicit modeling of solids and surfaces to parametric and direct modelling.

Temperature-Independent Fault Detection of Solenoid-Actuated Proportional Valve

Most electrically actuated hydraulic valves utilize solenoids as the actuating element due to their robustness and simplicity. This goes for both <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on–off</small> and proportional-type valves. However, despite their robustness, solenoid coil malfunction is the largest single failure mode in solenoid actuated valves. An outspoken fault is here solenoid winding short-circuit, i.e., two windings short-circuiting, which may ultimately lead to solenoid failure if more windings short-circuit. Research has therefore also focused on detecting winding short-circuits. Common for the approaches are that they, directly or indirectly, depend on the coil winding temperature, as this directly influences the coil resistance. Alternatively, the approaches are based on injection of high-frequency signals, which is typically a costly solution, which is not a feasible approach for use in hydraulic valves, with the limitations imposed by the control electronics. Therefore, this article focuses on a temperature-independent algorithm to detect coil winding short-circuit, which is easy to implement and only relies on existing position and current sensors. The proposed algorithm is based on an extended Kalman filter, which estimates the coil resistance. As this resistance estimate is indirectly dependent on the coil temperature, a window-based cumulative sum fault detection method is included to detect transient changes in the coil resistance while compensating for the temperature variations. The algorithm is developed based on an experimentally validated model of the valve, and has been tested for several different situations through both simulations and experimentally. Based on the presented results, it is found that the algorithm can consistently detect resistance changes down to 0.11 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Omega$</tex-math></inline-formula> for constant input signals and down to 0.17 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Omega$</tex-math></inline-formula> for sinusoidal-varying input signals. This while stillbeing robust to parameter variations, such as increased valve friction, spring coefficients, and sensor signal deviations.

A review on the employment of the hydraulic cylinder for lifting purposes

The hydraulic elevator is both a cost-effective system and results in extremely clean building exterior lines since the usual penthouse-type machine room is eliminated. Without the need for wires, counterweights, or pulleys, this elevator can transfer people between levels. One of the most significant factors to consider when designing people's elevators is that they should not be disturbed when going between levels and that the elevators should stop accurately. As a consequence, innovative technologies such as the electro-hydraulic servo system (EHSS) may be employed with a traditional hydraulic elevator. This technology may employ speed and position input to provide the desired degrees of speed control, riding comfort, and leveling precision. The EHSS is a closed-loop control system that operates as a drive unit, raising and lowering the elevator cabin in response to a variable like position, velocity, or force. This paper examines various types of hydraulic systems for lifting purposes, as well as the application of servo system principles to hydraulic control valves, to credibly provide the traditional hydraulic elevator with a selectable diversity of precise and smooth transport characteristics across floors. This study also looks at how elevators employ telescopic hydraulic cylinders efficiently for lift purposes in the elevator.

Research on Hydraulic Servo Valve Control Based on Fuzzy RBF

Aiming at the problems of low control precision and slow response speed of traditional control of actuators in hydraulic systems, the mathematical model of the valve-controlled cylinder is established as the research object, and the control strategy of fuzzy RBF neural network is proposed to control hydraulic servo valves On the basis of traditional fuzzy control, fuzzy control and RBF neural network control are integrated. According to the mathematical model of the system, a tracking controller is designed to realize precise control and real-time feedback of the valve-controlled cylinder system. The simulation results show that compared with traditional PID and fuzzy PID systems, the fuzzy RBF neural network strategy has high control precision, fast response speed, better robustness, and stability.

Particle erosion transient process visualization and influencing factors of the hydraulic servo spool valve orifice

The erosion of the valve orifice can easily lead to the performance degradation of the hydraulic servo spool valve, which seriously affects the service life and reliability of the hydraulic servo system. In this paper, the erosion micro-morphological characteristics, erosive transient process visualization of solid particles, and factors affecting the erosion rate of the spool working edges were investigated. The results showed that there was a significant “edge collapse” phenomenon on the working edges of the spool, which was mainly characterized by surface peeling, notches, grooves, chamfers, and the radius of the fillet which fluctuated violently in the circumferential direction. The “smoothing, slipping, and somersaulting” evolution process started when the incident angle increased and the particles hit the valve orifice by a new visualization experiment model composed of the nozzle-baffle submerged jet. The erosion rate of the working edges also showed continuous fluctuations and violent changes, with strong scatter-like distribution characteristics. The erosion rate of the working edge in the up-flow field was approximately one time higher than that in the back-flow field. The erosion rate of the working edges increased as the oil viscosity and particle concentration increased. Under small openings, the impact frequency of particles and the working edge increased significantly. The distribution law of the erosion rate of the working edge agreed with the distribution characteristics of the erosion fillet radius of the working edges. The erosion rate variance was defined, which can be used to quantify the circular distribution of erosion rate. This study provides further understanding of the mechanism and influencing factors of the hydraulic servo spool valve erosion.