• 제목/요약/키워드: 유압밸브

검색결과 245건 처리시간 0.024초

유압 제어계에서 서보밸브 선형화 방정식의 오차 평가 (Error Evaluation of Linearized Equation for a Servovalve in Hydraulic Control Systems)

  • 김태형;이일영
    • 대한기계학회논문집A
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    • 제27권5호
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    • pp.779-788
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    • 2003
  • This study evaluates the approximation errors of the existing linearized equation for a servovalve nonlinear flowrate characteristic. At first, the errors are evaluated on flowrate/pressure characteristics diagrams. Subsequently, they are investigated with time response simulation results for several hydraulic control systems. To enable systematic evaluation of computational error, the authors propose three kinds of equations with restructured forms of the existing linearized equation. As results of the evaluations, it is ascertained that comparatively good computational accuracy can be achieved with the existing linearized equation when both an operating point for the linearized equation and operating range of the hydraulic system stay near the flowrate axis of the flowrate/pressure characteristics diagram. In addition, the results show that comparatively big computational error may occur when operating range of a hydraulic system stay apart from the flowrate axis of the flowrate/pressure characteristics diagram.

유압 제어계에서 서보밸브 모델링을 위한 새로운 선형화 방정식의 제안 (A New Linearized Equation for Modelling a Servovalve in Hydraulic Control Systems)

  • 김태형;이일영
    • 대한기계학회논문집A
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    • 제27권5호
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    • pp.789-797
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    • 2003
  • In the procedure of the hydraulic control system design, a linearized approximate equation described by the first order terms of Taylor series has been widely used. Such a linearized equation is effective just near the operating point, However, pressure and flowrate in actual hydraulic systems are usually not confined near an operating point. This study suggests a new linearized flow equation for a servovalve as a modified form of the conventional linearized flow equation. Subsequently, a procedure to determine effective operating point for the new linearized equation is proposed. From the evaluations of time responses and frequency responses obtained from simulations for a hydraulic control system, the effectiveness of the new linearized equation and the procedure to determine effective operating point is confirmed.

고속전자밸브를 이용한 유압실린더의 PWM 제어에 관한 연구 (A Study on PWM Control of Hydraulic Cylinder Using High Speed Solenoid Valve)

  • Park, S.H.;Lee, J.K.
    • 한국정밀공학회지
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    • 제12권7호
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    • pp.138-147
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    • 1995
  • The conventional PWM method, which was used in controlling the on-off valve, such as high-speed solenoid valve, was modulating the width of the pulse applied to the valve, by selecting arbitrary sampling time and modulating the duty-ratio in proportion to the error. However, in this method, a selection of long sampling time was inevitable and it was unable to get a high accuracy and a quick response. This study is for designing an appropriate controller for high-speed solenoid valve by proposing an improved duty-ratio modulation method using the Saw-toothed Carrier Wave which enables a short sampling time selection, high accuracy of control, and a quick response. Test which was carried out in the laboratory shows that transient and steady state response could be improved by PID controller.

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고속전자밸브를 이용한 유압전동장치의 속도 제어에 관한 연구 (A Study on Speed Control of Hydrostatic Transmission Using High Speed Solenoid Valve)

  • Park, S.H.;Lee, J.K.
    • 한국정밀공학회지
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    • 제12권7호
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    • pp.148-157
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    • 1995
  • This study deals with controlling the speed of Hydrostatic Transmission (HST) system throuth the control of pumping stroke of positive displacement pump using high-speed solenoid valve controlled by digital closed loop PWM method. The method which was done in this study is as follows: First, we modified original positive displacement pump and designed pumping stroke control system of HST by using the high-speed solenoid valve. Second, after experimenting static and dynamic characteristics on each signal flow, we identified system parameter of approximated model. Finally, to control the speed of HST, we controlled the angle of the swash plate of positive displacement pump by controlling the pressure in the control cylinder chamber. Test which was carried out in the laboratory shows that transient and steady state response could be improved by PID controller.

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전자유압 서보 유량제어밸브의 설계 및 동특성 향상에 관한 연구 (A Study on the Design and the Dynamic Characteristics of Electro-Hydraulic Flow Control Servo Valve)

  • 김고도;김수태
    • 한국정밀공학회지
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    • 제17권2호
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    • pp.151-160
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    • 2000
  • An experimental and theoretical analysis for the improvement of dynamic characteristics and design of electro-hydraulic flow control servo valve are performed. The theoretical results are compared with the experimental step responses, and the important design parameters of an electro-hydraulic flow control servo valve are derived by using the simulation program. Simulation parameters of nozzle jet coefficient and orifice and spool valve discharge coefficient are given through experiment. The theoretical and experimental step response curves show that the valve gain depends on the fixed orifice and nozzle $ratio(R_on)$ and is maximum at $R_on=1.$ And drain orifice in the flapper - nozzle return line creates a small back pressure, which improves the performance fur the valve.

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전기유압 서보밸브 플랩퍼-노즐에 대한 변동 배유 오리피스의 영향 해석 1 (An Analysis of the Effect of a Variant Drain Orifice Damping on an Electrohydraulic Servovalve Flapper-Nozzle Stage)

  • 이재천
    • 한국정밀공학회지
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    • 제16권2호통권95호
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    • pp.50-59
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    • 1999
  • The effect of a variant drain orifice damping on the characteristics of a servovalve flapper-nozzle stage is analyzed. Steady-state characteristics of flapper-nozzle stage and the linearized dynamics of flapper-nozzle assembly with a spool valve show that the variant drain orifice damping could improve such null performance characteristics as null pressure sensitivity and linearity of gain function. Generalized design criterion and a sufficient condition for servovalve stability are also established.

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고속전자밸브를 사용한 유압장치의 PWM 제어에 관한 연구 (A Study on the PWM Control of Hydraulic Equipment Using High Speed On-Off Valve)

  • 허준영
    • 대한기계학회논문집
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    • 제19권3호
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    • pp.868-876
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    • 1995
  • This study deals with a position control of an electro-hydraulic servo system which consist of cylinder and high speed on-off valves operated by microcomputer. The merits of PWM control of hydraulic equipment are the robustness of the high spee on-off valve, its low price and the direct control without D/A converter. In the PWM control of high speed on-off valve, the time lag and switching time existing between the input and output signals of valve are considered as demerit points. To get analytical results, the effects of these demerits have to be clarified in detail. The object of this study is to propose a mathematical model for the behavior of high speed on-off valve and to get analytical results of this system. The dynamic characteristics of this system is examined by digital computer simulation analytically and compared with experimental results to varify the proposed mathematical model.

고속응답 전자밸브에 의한 유압 모터계의 PWM 제어 (PWM Control of Hydraulic Motor Systems Using High Speed Solenoid Valves)

  • 김도태
    • 한국공작기계학회:학술대회논문집
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    • 한국공작기계학회 1999년도 추계학술대회 논문집 - 한국공작기계학회
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    • pp.387-392
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    • 1999
  • The micro electronic control technology with developing microcomputers make great contribution to electrohydraulic control systems. The electrohydraulic pulse control simplifies in conjunction with power electronic amplifier and high speed operated solenoid valves. It is necessary to valves to convert electronic pulse signal to hydraulic pulse flow as fast as possible. This study deals with the speed control of an oil hydraulic motor operated by two way high speed solenoid valves. The valves acts as converters of electronic-pulse signals to hydraulic power. By constructing systems in which a hydraulic motor is operated by two solenoid valves, the pulse with modulation method (PWM) has adopted as the speed control of hydraulic motor systems. The static and dynamic characteristics of the systems are investigated by the experiment. It is clarify that a hydraulic motor operated PWM show good performance as a control component, achieving accurate velocity control.

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압력제어용 직동 밸브를 이용한 전기.유압 서보시스템의 힘 제어 (Force Control of Electro-Hydraulic Servo System using Direct Drive Valve for Pressure Control)

  • 이창돈;이진걸
    • 유공압시스템학회논문집
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    • 제1권3호
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    • pp.14-19
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    • 2004
  • The Direct Drive Valve used in this study contains a pressure-feedback-loop in itself, then it can eliminate nonlinearity such as the square-root-term in flow rate calculation and the change of bulk modulus of hydraulic oil. In this study, assuming that the dynamic characteristic of the DDV is modelled as a first order lag system, an parameter identification method using the input data and the output data is applied to obtain DDV's mathematical model. Then, a state feedback controller was designed to implement the force control of hydraulic system, and the control performance was evaluated.

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고속 온-오프 전자 밸브를 사용한 유압 실린더의 압력 제어 (Pressure Control of Hydraulic Cylinder using high Speed On-Off Solenoid Valve)

  • 김상수
    • Journal of Advanced Marine Engineering and Technology
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    • 제23권1호
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    • pp.69-78
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    • 1999
  • In this study a new pattern of pressure control of hydraulic cylinder using high speed On-Off solenoid valve in the electro-hydraulic system has been suggested. The control valve is 3-way high speed On-Off solenoid valve which is operated by PWM(Pulse Width Modulation)control signal. The high speed On-Off solenoid valve has a tendency to induce severe pressure fluctuation in the hydraulic actuator so it has not been used for the purpose of closed loop control with direct pres-sure feedback. In this study closed loop control with direct pressure feedback is enabled by using a digital filter which has linear minimum mean square filter algorithm. Through some experiments it is confirmed that stable pressure control can be realized by the proposed control technique.

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