• Title/Summary/Keyword: electro-hydraulic valve

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Impact performance for high frequency hydraulic rock drill drifter with sleeve valve

  • Guo, Yong;Yang, Shu Yi;Liu, De Shun;Zhang, Long Yan;Chen, Jian Wen
    • International Journal of Fluid Machinery and Systems
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    • v.9 no.1
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    • pp.39-46
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    • 2016
  • A high frequency hydraulic rock drill drifter with sleeve valve is developed to use on arm of excavator. In order to ensure optimal working parameters of impact system for the new hydraulic rock drill drifter controlled by sleeve valve, the performance test system is built using the arm and the hydraulic source of excavator. The evaluation indexes are gained through measurement of working pressure, supply oil flow and stress wave. The relations of working parameters to impact system performance are analyzed. The result demonstrates that the maximum impact energy of the drill drifter is 98.34J with impact frequency of 71HZ. Optimal pressure of YZ45 rock drill is 12.8 MPa-13.6MPa, in which the energy efficiency reaches above 58.6%, and feature moment of energy distribution is more than 0.650.

Static Analysis of Dedicated Proportional Flow Control Valve for IMV (굴삭기 IMV용 비례 유량제어밸브 정특성 해석)

  • Jung, Gyuhong
    • Journal of Drive and Control
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    • v.15 no.4
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    • pp.39-47
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    • 2018
  • Recently, as environmental regulations for earth-moving equipment have been tightening, advanced systems such as electronic control, have been introduced for energy savings. An IMV (Independent Metering Valve) consisting of four 2-way valves, is an electro-hydraulic control systems that provides more flexible controllability, and potential for energy savings in excavators, when compared to the conventional 4-way spool valve system. To fully maximize use of an IMV, the bi-directional flow control valve that can regulate a large amount of flow in both directions, should be adopted. The hydraulic circuit of an IMV applied to an excavator from an overseas construction equipment company, reveals the flow control valve with the compound of proportional solenoid valve for first stage, and 2-way spool valve for the second stage. Moreover, the two spools are interconnected by a feedback spring, presumed to compensate for flow force acting on the second stage spool. This paper addresses the static analysis of flow control valve in an IMV to investigate the improvement of robustness, against flow force by the feedback spring. From the steady-state analysis of flow control valve model, it can be concluded that the feedback spring facilitates maintaining linearity of spool displacement for control input, and relatively constant flow for load disturbance.

Wheel slip control of automotive brake system using ER valve (ER 밸브를 이용한 자동차 브레이크 시스템의 차륜 슬립제어)

  • 방주현;최승복
    • 제어로봇시스템학회:학술대회논문집
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    • 1997.10a
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    • pp.357-360
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    • 1997
  • This paper presents a new anti-lock brake system(ABS) using electro-rheological(ER) valve actuators for the wheel slip control. The hydraulic dynamic model of the automotive brake system is formulated by incorporating electric field-dependent Bingham properties of ER fluid obtained experimentally. The brake system designed by this hydraulic model is able to control wheel slip by controlling the intensity of electric field which tunes the braking torque. The control fields of the ER valve to command desired wheel slip are determined by a sliding mode controller. A comparison between the proposed brake system and the conventional brake system is made by providing with computer simulations of vehicle motions under ABS performance requirement condition.

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A high speed electro-hydraulic no leakage servo valve using multilayered piezoelectric devices (PZT) and an observer

  • Yokota, Shinichi;Park, Jung-Ho;Fuwa, Akihiko
    • 제어로봇시스템학회:학술대회논문집
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    • 1994.10a
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    • pp.54-59
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    • 1994
  • In this study, a high-speed servo valve with no outer leakage is developed, which is used to drive flexible hydraulic actuators (FHA) for extreme environments. In the valve, multilayered PZT devices are used to drive a spool directly and quickly. A bellows is also used to prevent outer leak from the clearance between the spool and the sleeve. Employing a disturbance observer, the lack of the system damping of the valve is improved by feeding back the estimated velocity of the spool, as well as the estimated disturbance is fed back to eliminate effectively the hysteresis between input voltage and output displacement of the PZT devices.

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A Study on the Control Characteristics of ER Valve-FHA System and Durability Test

  • Jang Sung-Cheol;Chang Tae-Hyun
    • Journal of Mechanical Science and Technology
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    • v.19 no.8
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    • pp.1621-1631
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    • 2005
  • In this paper, making the best use of the features of the electro-rheological (ER) valve, a two-port pressure control valve using ER fluids is proposed and manufactured. The ER-Valve characteristics are evaluated by changing the intensity of the electric field and the number of electrode. As only with electrical signal change to the ER-Valve in which ER fluid flowing, ER fluid flow is controlled, so development of simple ER-Valves have been tried. The ER-Valves and pressure drop check method are considered to be applied to the fluid power industry. Using the manufactured pressure control valve, a one-link manipulator with FHA (Flexible Hydraulic Actuator) is driven. As a result, it is experimentally confirmed that the pressure control valve using ER fluids is applicable to use in driving actuator. If it applies characteristics of the ER fluids, it will be able to apply in the control system for the ER Valve which occurs from industrial controller. After having durability test, shear stress increased regularly because of starch particles crushed by pump and particle size that was almost the same. Moreover, Ra of copper electrode increased about 1.56 times rather than before those of performing durability test, and Rz increased about 2.2 times.

Improvement of the Low-Speed Friction Characteristics of a Hydraulic Piston Pump by PVD-Coating of TiN

  • Hong Yeh-Sun;Lee Sang-Yul;Kim Sung-Hun;Lim Hyun-Sik
    • Journal of Mechanical Science and Technology
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    • v.20 no.3
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    • pp.358-365
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    • 2006
  • The hydraulic pump of an Electro-hydrostatic Actuator should be able to quickly feed large volume of oil into hydraulic cylinder in order to reduce the response time. On the other hand, it should be also able to precisely dispense small amount of oil through low-speed operation so that the steady state position control error of the actuator can be accurately compensated. Within the scope of axial piston type hydraulic pumps, this paper is focused on the investigation how the surface treatment of their cylinder barrel with TiN plasma coating can contribute to the reduction of the friction and wear rate of valve plate in the low-speed range with mixed lubrication. The results showed that the friction torque of the valve plate mated with a TiN coated cylinder barrel could be reduced to 22% of that with an uncoated original one when load pressure was 300 bar and rotational speed 100 rpm. It means that the torque efficiency of the test pump was expected to increase more than 1.3% under the same working condition. At the same time, the wear rate of the valve plate could be reduced to $40\sim50%$.

Performance Analysis of an Electro-Hydrostatic Actuator (Electro-Hydrostatic Actuator의 성능해석)

  • Kim, Do-Hyun;Kim, Doo-Man;Hong, Yeh-Sun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.35 no.4
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    • pp.316-322
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    • 2007
  • The EHA(Electro-hydrostatic Actuator) reveals completely different characteristics from the conventional valve-controlled Electro-hydraulic actuators. In this paper, its mathematical model including nonlinear elements was derived to be verified by experiments. Based on this, a simulation program was developed for the EHAs consisting of an electric motor driven hydraulic pump, pipe lines and a cylinder. The influence of important design parameters such as peak motor torque and rotational inertia moment of the hydraulic pump on control performance was investigated, where the test condition was intentionally selected so that the motor torque was saturated during the transient phase. As a result, design requirements for improving the control accuracy under full speed operation conditions of the EHAs were investigated.

A Study on the Speed Control of Electro - hydraulic Servo System under Load Disturbance (부하외란이 가해지는 전기.유압서보계의 속도 제어에 관한 연구)

  • 하석홍;권기수;이진걸
    • Journal of Advanced Marine Engineering and Technology
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    • v.17 no.1
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    • pp.26-32
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    • 1993
  • The loads exerted on electro-hydraulic servo system are classified into inertial, viscous, and spring load. The additional load called disturbances is also exerted on system but is generally not modeled. To deal with these kinds of loads, it is necessary to maintain the continuous signal transfer, so we can construct compensator to satisfy control specifications using feedback signal such as displacement, velocity, acceleration and pressure known as state variables. In case of controlling the speed of hydraulic motor, we must keep up robust performance for the various loads and disturbances acted on the system. However, the load flow rate in the valve is characterized by nonlinearity so that traditional theory of linear control could not be expected to give the desired performance. In this paper, it is shown that speed controller of hydraulic motor gives a good command following and disturbance rejection performance by applying sliding mode theory as a way of robust control to the nonlinearity, variation of loads and disturbances.

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A Study on Analysis of Non linear Frequency Response of Electro-Hydraulic Systems (전기 유압 시스템의 비선형 주파수 응답 해석에 관한 연구)

  • Lee, Yong-Joo;Jun, Bong-Geon;Song, Chang-Seop
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.1 s.94
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    • pp.246-252
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    • 1999
  • In this paper, the frequency response characteristics of the velocity controlled EHS system obtained by linear simulation method, nonlinear simulation method, and experimentation are compared one another, in order to verify propriety of the linearization method in case of analysis of hydraulic systems. The Bode diagrams are obtained by transforming time domain data of experimental results and nonlinear simulated ones with Fourier transform. The results of nonlinear simulation are more similar to the frequency response of the real systems than those of linear simulation. It is found that nonlinearity of hydraulic systems is mainly occurred from servo valve, and nonlinearity is increased as displacement of servo valve spool increases.

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Pressure Control of Electro-Hydraulic Servo System by Two-Degree of Freedom Control Scheme (2자유도 제어기법에 의한 전자 유압 서보계의 압력제어)

  • 양경욱;오인호;이일영
    • Journal of Advanced Marine Engineering and Technology
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    • v.20 no.3
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    • pp.110-120
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    • 1996
  • The purpose of this study is to build up the control scheme that promptly controls the pressure in a hydraulic cylinder having small control volume, using a PCV(proportional control valve) and a digital computer. Object pressure control system has the character to be unstable easily, because the displacement-flow gain of the PCV is so large considering comparatively small volume of the hydraulic cylinder and the time delay of response of PCV is long. Considering the above-mentioned characteristics of the object pressure control system, in this study, a control system is designed with two degree of freedom scheme that is composed by adding a feed-forward control path to I-PD control system, and the reference model is used to decide control parameters. And through some experiments on FF-I-PD, the validity of this control method is confirmed.

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