Electro-hydraulic Valve Research Articles

Research on Double Hanging Point Hydraulic Synchronous Control System Based on Fuzzy PID

Hydraulic hoist is required to open and close the gate. In recent years, scholars have studied a lot of different types of hydraulic hoist, in which the double point hydraulic hoist is one of them. Double point crane hydraulic hoist mainly uses the hydraulic synchronous system. In this paper, the hydraulic synchronous system as the research object, through the electrohydraulic proportional speed control valve research, analysis of its working principle. Then, the traditional PID control method and the fuzzy PID control method are compared and analyzed. It is found that the fuzzy PID control ability is better than the traditional PID control method. Fuzzy PID realizes hydraulic synchronization by adjusting the electro-hydraulic ratio of speed control valve.

Electro-Hydraulic Proportional Position Control Using Auto Disturbance Rejection Based on RBF Neural Network

Large friction force and large dead zone are two typical nonlinear characteristics of electro-hydraulic proportional valve controlled hydraulic cylinder position control system. Aiming at those characteristics, a dead zone dynamic compensation algorithm is researched in order to reduce the lag time and control error. At the same time, a control strategy of radial basis function (RBF) neural network combined with auto disturbance rejection control (ADRC) is researched according to the impact of different conditions. The experimental result shows that the proposed algorithm improves performance of the electro-hydraulic proportional valve controlled hydraulic cylinder position control system. In positioning control experiment, the overshoot is 0 and the stability error is 0. In tracking control experiment, the lag time is reduced from the original 1.5 s to 0.2 s with no flat top phenomenon and the maximum error was reduced from 20 mm to 3 mm.

Research on the performance of a novel electro-hydraulic proportional directional valve with position-feedback groove

Accurate posture control of hydraulic roof supports, which use pressurized water as their fluid power source, is an important part and research direction of intelligent fully mechanized mining face. At present, the large flow on/off directional valve used on the hydraulic roof support cannot meet the requirement of precise posture control of the roof support. To overcome the conundrum, a novel two-position three-way electro-hydraulic proportional directional flow valve for hydraulic roof support is proposed. The new valve contains two pilot stages and two main spools. The two pilot stages cooperate with each other to control the movement of the two main valve spools, which are the inlet valve spool and the outlet valve spool. The inlet valve spool adopts the Valvistor principle. The valve can realize manual pilot control and electro-hydraulic proportional flow control of the passage P-A, which has been verified by a simulation model. In this paper, the static and dynamic mathematical models of the new proportional valve are established, and the key parameters affecting the valve performances are analyzed and verified by the simulation model. An optimization control scheme is proposed to overcome the influence of supply pressure, P-A pressure difference, and nonlinear interference force on steady-state displacement and response speed of the valve. The results show that this optimization method can significantly improve the response speed of the spool and promote the linearity of spool displacement under a slope signal. In addition, the fluctuation of chamber pressure and spool displacement caused by the discontinuous flow of a fast switching valve is systematically analyzed. The analysis shows that increasing pulse-width modulation carrier frequency is an effective way to reduce fluctuation amplitude. The research provides a new design idea and control method for an electro-hydraulic proportional directional valve of hydraulic roof support.

A fault diagnosis method for an electro-hydraulic directional valve based on intrinsic mode functions and weighted densely connected convolutional networks

Wear caused by contaminated oil or frequent reciprocating of the spool is the chief source of internal leakage in electro-hydraulic directional valves. It is difficult to detect the location and extent of the internal wear of directional valves because the hydraulic transmission works in a closed system. Therefore, this paper focuses on the internal leakage fault diagnosis caused by the wear based on intrinsic mode functions (IMFs) and weighted densely connected convolutional networks (WDenseNets), especially for electro-hydraulic directional valves. First, the empirical mode decomposition is performed in three subsections, respectively, and a series of IMF components are obtained correspondingly. Combined with the ReliefF feature selection algorithm, the optimal IMF component is selected. The weights assigned to the optimal IMF mode are normalized and then weighted as the subsequent diagnostic feature vector. Then, a WDenseNet inspired by squeeze-and-excitation networks is designed. Finally, the weighted optimal IMF component is used as the input for the WDenseNet for fault identification and classification. In addition, an experimental method to investigate the internal leakage faults associated with wear is developed. Theoretical and experimental results indicate that the fault diagnosis method can be used to identify the type of internal leakage and wear location in electro-hydraulic directional valves. Compared with other intelligent diagnosis methods, this method has higher diagnostic accuracy and better training stability. The effectiveness of the proposed method is also verified through an experimental study of the bearing fault in an axial piston pump.

Modeling and Research of Fuzzy PID Control Strategy for Hydraulic Rock Drill Propulsion System

According to the coupling characteristic of propulsion system and impact system of hydraulic rock drill, deduced the calculation formula of optimal axial thrust for the propulsion system of hydraulic rock drill. On the basics of the calculation formula before, the paper constructed compound driven propulsion system of hydraulic rock drill based on electro-hydraulic proportional pressure-reducing valve and high speed on-off valve, and established its dynamics model. Finally, the paper considered optimal axial thrust as the goal, and adopted the fuzzy PID control strategy to realize on-line, intelligent control to axial thrust of the propulsion system of hydraulic rock drill. Through mathematical modelling and simulation study show that fuzzy PID control method has its advantages as the fast response follow by target, high control precision, and small fluctuation, and provided theory reference and technology method for intelligent control of the propulsion system of hydraulic rock drill.

Novel Magnetic Circuit Topology of Linear Force Motor for High Energy Utilization of Permanent Magnet: Analytical Modelling and Experiment

The magnetic circuit of existing linear force motors does not consider the issue of energy utilization of permanent magnets, and the structure is complicated. To achieve high energy utilization and simplify the structure, this paper presents a novel magnetic circuit topology for the linear force motors of electro-hydraulic servo-proportional valves. In order to rapidly and accurately calculate the static characteristics of the force motor, an analytical model is established by using the equivalent magnetic circuit method. The model comprehensively considers the magnetic leakage effect, edge effect, and permeability nonlinearity. A prototype of the force motor is designed and manufactured, and a special experimental platform is built. The prototype force motor has a linear force-displacement characteristic and the output force increases with the increase of the excitation currents, which can reach about 41 N at 2 A. This indicates that it is suitable as an electro-mechanical converter for electro-hydraulic servo-proportional valves. Moreover, the analytical model is used to perform parameter optimization and calculate the magnetic flux density in the working air gap and the force-displacement characteristics under different excitation currents. The results are in good agreement with the electromagnetic field finite element simulation and experimental results. They indicate that the analytical model can rapidly and accurately predict the static characteristics of the force motor. The research work provides good reference means for the design of magnetic circuit topology with consideration of the high energy utilization of permanent magnets, and also the accurate analytical modeling of valve electro-mechanical converters.

Fault Diagnosis for Internal Leakage of Electro-hydraulic Directional Valve Based on EMD and One-dimensional Densely Connected Convolutional Networks

Fault Diagnosis for Internal Leakage of Electro-hydraulic Directional Valve Based on EMD and One-dimensional Densely Connected Convolutional Networks

Development of a new mechanical electro hydraulic valvetrain system

Variable valve actuation (VVA) technologies can provide improvements in fuel economy of spark-ignition (SI) engines by shifting valve timings or generating valve profiles that can minimize pumping loss. Electro hydraulic valve (EHV) is one of VVA technologies that is highly flexible in producing valve profiles to control charge mass without throttle. In this work, a new EHV which has a unique operating mode, namely mechanical mode, is introduced. The mechanical mode enables operation of valvetrain under circumstances of EHV malfunctions: the mechanical electro-hydraulic valvetrain (MEHV) developed in this study was capable of stable operation under various operating modes at wide ranges of oil temperatures and cam speeds with appropriate valve seating velocity and ramp duration. The MEHV is a VVA technology that can resolve issues of previous EHVs which lacked reliability under emergency conditions.

Research on mechanical-hydraulic system simulation method for multi-control multiway valve

Based on the control principle and flow distribution characteristics of the electro-hydraulic proportional load-sensitive multiway valve in an excavator, a system simulation model is established in AMEsim. After proving the accuracy of this model by comparing simulation results with theoretical results for various flow distribution characteristics under saturated and unsaturated conditions, this model is used to study the effect of three-way valve preload on the multiway valve system to prove that the simulation method can evaluate the influence of design parameters on the multiway valve system and then guide the design of multiway valves.

Internal leakage analysis and experiment in hydraulic control system of steam turbine inlet valve

In this paper, the transformation of steam turbine regulating system from mechanical hydraulic regulation to electro-hydraulic regulation is realized. And the internal leakage mechanism of the hydraulic control switch valve and the electro-hydraulic proportional valve in the system is analyzed. With the use of hydraulic simulation software AMESim, the mathematical model of the electro-hydraulic control system after transforming is established. The parameters of the hydraulic control switch valve and the electro-hydraulic proportional valve in the hydraulic control system of steam turbine inlet valve are studied under different internal leakage locations and different leakage degree, such as piston regulating time, steady position of piston, oil pressure and leakage flow flux. The fault characteristic table of internal leakage is obtained. An experimental platform for simulating internal leakage is built. The experimental curves of several physical quantities under different internal leakage conditions are obtained. The experimental results prove that the internal leakage has a great impact on the performance of the electro-hydraulic control system. The results of internal leakage experiment are consistent with those of internal leakage simulation.

Feedforward Plus Feedback Control of an Electro-Hydraulic Valve System Using a Proportional Control Valve

The output feedback signal of the electro-hydraulic valve system (EHVS) affects the activation of its right or left envelope function; thus, even weak measurement noise can cause high-frequency switching between the two envelope functions, leading to chattering in the control input. Consequently, feedforward and feedback controllers in a cascaded configuration generate undesirable chattering in the output signal. We propose a practical and reliable control approach for an EHVS actuated by a proportional control valve. The proposed controller has a parallel structure comprising an inverse generalized Prandtl–Ishlinskii (P–I) model-based feedforward controller, with both hydraulic dead-zone and flow saturation limits, for compensating asymmetric hysteretic behavior. Further, the proposed controller comprises a robust proportional-integral-derivative (PID) feedback controller for achieving robustness against disturbances and noises. The proposed parallel structure is independent of the output feedback of the EHVS. Moreover, the proposed robust PID feedback controller guarantees EHVS stability by precisely selecting the cutoff frequency for the sensitivity and complementary sensitivity functions based on the amplitude spectrum of the inverse-model-based feedforward compensation error. The results verify the high reliability of the proposed EHVS control scheme for the precise control of an EHVS actuated by a proportional control valve in practice.

РАСЧЕТ ДИНАМИЧЕСКОЙ ХАРАКТЕРИСТИКИ ЭЛЕКТРОГИДРАВЛИЧЕСКОГО ПРЕОБРАЗОВАТЕЛЯ ТИПА СОПЛО-ЗАСЛОНКА ДЛЯ МОДЕРНИЗАЦИИ СИСТЕМЫ УПРАВЛЕНИЯ ТОПЛИВОПОДАЧЕЙ ДВИГАТЕЛЯ АВТОМОБИЛЯ

At the current stage of the development of means for automatic control for the formation of qualitative systems of machines, construction and road machinery, railway transport there are used electro-hydraulic devices transforming electric input signals into hydraulic output power. To carry out a generalized analysis and for the fulfillment of the preliminary synthesis of an automated hydraulic system on the whole the static and dynamic characteristics of its separate units should be obtained. 
 In the paper there is presented a calculation of a theoretical dynamic characteristic of the electro-hydraulic nozzle-flap converter to substantiate potentialities of its inclusion as an adjusting device acting upon rods of a high-pressure fuel pump in the system of fuel feeding control of a KamAZ motor-car engine. At that the converter was considered as interconnected units: a unit of feedback. The methods of the investigation of processes in the converter are based on the fundamentals of the theory of automatic control. 
 As it follows from the transition function diagram obtained as a result of the investigations carried out the transition time of a electro-hydraulic converter slide valve movement from a neutral position into an extreme one in the course of sending a maximum control signal to the coil does not exceed 1.1 sec, that is satisfactory for the formation of hydraulic drive control systems.

Effect of the Intake Valve Lift and Closing Angle on Part Load Efficiency of a Spark Ignition Engine

This study provides an experimental evaluation of the effectiveness of Miller cycles with various combinations of lift and intake valve closing angle for a passenger car engine with premixed combustion in naturally aspirated operation. A fully variable electro-hydraulic valve train provided different valve lift profiles. Six load points, from 1.5 up to 5 bar brake mean effective pressure at a constant engine speed of 2000 min−1, were tested with 6 different intake valve lift/intake valve closing angle combinations. The intake valve closing angle was always set before bottom dead center to achieve the desired load with unthrottled operations. Experimental comparison with throttled operation outlines an indicated efficiency increase of up to 10% using high intake lift with early valve closing angle. Furthermore, this analysis outlines the influences that early intake valve closing angle has on fuel energy disposition. Longer combustion duration occurs using early intake valve closing angle because of turbulence dissipation effects, leading to slight reductions in the heat-to-work efficiency. However, overall pressure and temperature levels decrease and consequently heat losses and losses due to incomplete combustion decrease as well. Overall, we found that combustion deterioration is compensated/mitigated by the reduction of the heat losses so that reductions of pumping losses using early intake valve closing can be fully exploited to increase the engine’s efficiency.

Modelling of an electro-hydraulic variable valve actuator for camless engines aimed at controlling valve lift parameters

This paper presents the mathematical modelling of an Electro-Hydraulic Valve Actuator (EHVA) prototype and its application to the design of cycle-by-cycle Valve Lift Control(VLC). EHVA is rated in the technical literature as an apparatus enabling Variable Valve Actuation (VVA) and implementation of advanced combustion concepts in future camless engines. It is, therefore, a first step towards the development of camless engines in which valve lift and timing can be freely adjusted valve-by-valve and cycle-by-cycle. Particular attention is paid to parameter identification aimed at obtaining a predictive simulation model of valve lift trajectories and valve parameters (e.g. lift, duration, area) for a wide range of system inputs. An energy loss assessment of a valvetrain based on EHVAs is described, and the results are compared with those obtained with a traditional cam-based valvetrain. The validated model is then used to build detailed numerical maps of valve parameters that are fundamental for setting up cycle-by-cycle controllers of valve parameters. Hence, the authors present the design of a cycle-by-cycle controller of maximum valve lift, the performance of which is tuned by simulations and then verified experimentally.

Review of Advancement in Variable Valve Actuation of Internal Combustion Engines

The increasing concerns of air pollution and energy usage led to the electrification of the vehicle powertrain system in recent years. On the other hand, internal combustion engines were the dominant vehicle power source for more than a century, and they will continue to be used in most vehicles for decades to come; thus, it is necessary to employ advanced technologies to replace traditional mechanical systems with mechatronic systems to meet the ever-increasing demand of continuously improving engine efficiency with reduced emissions, where engine intake and the exhaust valve system represent key subsystems that affect the engine combustion efficiency and emissions. This paper reviews variable engine valve systems, including hydraulic and electrical variable valve timing systems, hydraulic multistep lift systems, continuously variable lift and timing valve systems, lost-motion systems, and electro-magnetic, electro-hydraulic, and electro-pneumatic variable valve actuation systems.

Simulation Study on Static and Dynamic Characteristics of Electromagnet for Electro-Hydraulic Proportional Valve Used in Shock Absorber

In order to improve the performance of the electromagnet for electro-hydraulic proportional valve used in shock absorber, the static and dynamic characteristics of the proportional electromagnet are simulated and analyzed, which provides theoretical basis for the design and optimization of structural parameters of the proportional electromagnet. In this paper, the magnetic circuit model and finite element simulation model of the proportional electromagnet used in shock absorber are established, and the Ansoft software is applied to analyze the influence of the key structural parameters of the proportional electromagnet on static output force and dynamic characteristics. The results demonstrate that with the increase of the depth of basin mouth, the effective travel of the proportional electromagnet increases, and the mean value of the electromagnetic force in the working range decreases. The larger the radial clearance between armature and guide sleeve is, the smaller the electromagnetic force in the effective travel is. When the depth of the basin mouth is 3.9 mm, the slope of the magnetic isolation ring is 35°, the chamfer length of the convex platform is 0.2 mm, and the radial clearance is 0.3 mm, the proportional electromagnet has good displacement-force and current-force characteristics. According to the further transient analysis, it is found that when the voltage amplitude is 24 V, the rise time of the electromagnetic force under step excitation signal is about 40 ms.

Solution for controlling a hydraulic motor using cloud data

In the last period, Internet of Things (IoT) is experiencing an increasing development, and the tendency of hosting applications and especially data, in cloud computing systems is growing. Currently, most of the Building Management System (BMS) analyse directly data or transfer it to the cloud.In this context, the proposed solution aims to read indoor thermal climate data from cloud computing platform and based on them operate a hydraulic motor. The input data could be generated by an in-house sensor monitoring solution or by a foreign BMS system that transmits open source data to cloud.In this study some conditions are imposed to the input data and as a result, control current is generated and transmitted in order to command proportional electro-hydraulic valve that drive a hydraulic motor. The electro-hydraulic valve is controlled with the help of an amplifier, by a data acquisition board (DAQ) that runs LabView application. With the help of the developed software, the motor speed and the direction of rotation can be controlled.In last years, the number of requests for architectures projects with moveable elements has increased because they multiply the possible use of the buildings. With the information generated by the sensors that measure the indoor climate parameters, the hydraulic motor could be used in such a construction. Examples of atypical buildings with special functionalities that the architects would propose and that needs high torque actuation are presented in this paper.

New High Performance Electro-hydraulic Proportional Valve and Its Performance

New High Performance Electro-hydraulic Proportional Valve and Its Performance

Investigations of applications of smart materials and methods in fluid valves and drives

In the paper the investigations performed at the Division of Mechtronic Devices at Poznan University of Technology in the area of application of both: smart materials in electro-hydraulic and electro-pneumatic valves, and new methods to control of hydraulic servo drives, are presented. In a first part the piezo bender actuator is shortly described and its application in servo valve is proposed. This actuator replaced the torque motor in the available on the market servo valve. The new valve simulation model is proposed. The simulation and investigations results of the servo valve with the piezo bending actuator are included. In the next part of the paper the application of piezo tube actuator in flapper-nozzle pneumatic valve is described. The test stand and investigations results are presented. Later, in the article, the Model Following Control (MFC) and Fractional order Control (FoC) methods are described. Their application in control of electrohydraulic servo drive is proposed. Some investigations results are included in the paper, showing the advantages of those control methods.

High-response electrorheological servo valve

The demand of more powerful and high-dynamic hydraulic actuators gives the servo valve as a control member an increasingly important role. The valve should provide the hydraulic actuator with sufficient volume flow over wide frequency range to achieve large strains at high operating frequencies. Here, the electrorheological effect as an electrohydraulic valve drive offers great potential. It converts the electrical input signal directly into a controlling mechanical quantity within a few milliseconds and provides theoretically unlimited strain. Thus, the electrorheological effect has the ability to increase the performance of conventional hydraulic systems. This work presents a two-stage servo valve with an electrorheological pilot stage. Furthermore, it introduces a model to describe the static and dynamic properties of the system. The model is validated on the basis of measurement results.