• Title, Summary, Keyword: Hydraulic

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Reliability Assessment Standard Development of the Hydraulic Valves (유압밸브 신뢰성 평가 기준 개발)

  • 윤소남;황태영;김형의
    • Proceedings of the Korean Reliability Society Conference
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    • pp.99-104
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    • 2001
  • In this study, selecting methods of the hydraulic valve and evaluation item for development of reliability testing standard are c]early defined. And, we developed reliability testing standard of the hydraulic valves which are as follows, - Hydraulic directional control valve, - Hydraulic on-off solenoid valve - Hydraulic PWM valve, - Hydraulic check valve, - Hydraulic relief valve, - Hydraulic reducing valve, - Hydraulic flow control valve

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Determination of No-Failure Test Times for the Life Test of Hydraulic System Components (유압시스템 구성품의 수명시험을 위한 무고장 시험시간의 산출)

  • Lee, S.R.;Kim, H.E.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.3 no.3
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    • pp.8-13
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    • 2006
  • It is very important for the manufacturers to predict the life of hydraulic system components according to the results of life tests. Since it takes too much time to test the hydraulic system components until failure, the no-failure test method is applied for the life test of them. If the shape parameter of Weibull distribution, the number of samples, the confidence level, and the assurance life are given, the no-failure test times of hydraulic system components can be calculated by given equation. Here, the procedures to obtain the no-failure test times of the hydraulic system components such as hydraulic motors and pumps, hydraulic cylinders, hydraulic valves, hydraulic accumulators, hydraulic hoses, and hydraulic filters are described briefly.

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Development of the Hydraulic Pressure Transducer System for Testing the Impact Energy of Hydraulic Breaker (유압 브레이커의 타격 에너지 측정을 위한 유압 변환장치 개발)

  • 이근호;이용범;정동수
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.4
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    • pp.154-160
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    • 2004
  • Hydraulic breaker of excavator has been used for the destruction and disassembling of buildings, crashing road pavement, breaking rocks at quaky and etc. The performance of breakers is evaluated their own destructive force and the number of impact by input hydraulic flow rate and pressure on the operating conditions. Because hydraulic breakers generate high impact energy, the accurate measurement of the impact force has been facing a technical challenge. In this study, the hydraulic pressure transducer system was developed based on the characteristics of pressure variation in closed vessel fur testing the impact energy. The hydraulic pressure transducer system is consisted with a hydraulic cylinder, main base, pressure & temperature sensors, LVDT, data acquisition system and etc. The developed hydraulic pressure transducer system was applied to measure the impact energy for hydraulic breaker. The measured impact force was 438.8 kgf.m within the designed impact force bounds. The developed hydraulic pressure transducer system as a simple tester could be applied to measure the impact force and the number of impact.

The Estimation of Compacted State on Sea Dike Embankment with the Interrelationships Between the Hydraulic Head Loss Rate, the Hydraulic Conductivity and the Void Ratio (수두손실률, 투수계수 및 공극비의 상호관계를 통한 제체의 다짐상태 평가)

  • Eam, Sung Hoon
    • Journal of The Korean Society of Agricultural Engineers
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    • v.57 no.1
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    • pp.11-23
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    • 2015
  • In this study the laboratory test for hydraulic conductivity and the seepage analysis with finite element method on measurement section of sea dike embankment were performed for the purpose of estimating the relative density of embankment from the measured pore water pressures, and both results of the test and the analysis were coupled with the method of estimating seepage blocking state with the hydraulic head loss rate in sea dike embankment. The relationship of void ratio vs hydraulic head loss rate was obtained by setting hydraulic conductivity as common ordinate on the relationships between the void ratio and the hydraulic conductivity and between the hydraulic conductivity and the hydraulic head loss rate. The void ratio on the segment between measuring points was calculated from the coupled relationship of the void ratio vs the hydraulic conductivity. The allowable upper and lower limits of hydraulic head loss rate and those of void ratio on the safety were generated from the coupled relationship between the laboratory compaction test and the sedimentation test. Current hydraulic head loss rate and void ratio were evaluated in the allowable range between upper and lower limits.

Hydraulic Pulsation and Noise Reduction using the Helmholtz Attenuator (헬름홀츠 감쇠기를 응용한 유압시스템의 유압맥동 및 소음 최소화 연구)

  • 김동현;이대옥;최근국
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.614-619
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    • 1997
  • The hydraulic pressure pulsation has on the effected on the acoustic nosie and control performance of the hydraulic-servo system. The Helmholtz attenuator introduction on the hydraulic line is an efficient device to reduce the hydraulic pulsation. The salient feature of causing hydraulic pulsation and the frequency characteristics of Helmholtz attenuator are studied. The hydraulic filter design parameters such as the locating position, connecting orifice area and accumulator volume are mathematically analyzed. The instrumental works are carried out with the remarkable reduction of the hydraulic pressure pulsation magnitude and the acoustic noise level.

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Position Control of Hydraulic Motor-Load System using Matlab (Matlab을 이용한 유압모터-부하계의 위치제어)

  • 이명호;박형배
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.13 no.3
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    • pp.76-83
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    • 2004
  • The purpose of this paper is to find an effective control system for a hydraulic motor-load system using matlab. The Hydraulic control system consists of a hydraulic pump, a hydraulic proportional control valve, hydraulic pipelines, a hydraulic motor and a load system. The simulation models were verified by comparing the simulation results with measured data from the real hydraulic proportional position control system. In order to compensate the nonlinear friction characteristics in a hydraulic motor-load system, a discrete time PD controller and Friction torque observer has been applied.

Active Force Control of Electro-Hydraulic Hybrid Load Simulator using Quantitative Feedback Theory (QFT를 이용한 전기유압 하이브리드 부하 시뮬레이터의 능동 힘제어)

  • Yoon, Joo-Hyeon;Ahn, Kyoung-Kwan;Truong, Dinh Quang;Jo, Woo-Geun
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.2
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    • pp.45-53
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    • 2009
  • Today, reduction of $CO_2$ exhaustion gas for global-warming prevention becomes important issues in all industrial fields. Hydraulic systems have been widely used in industrial applications due to high power density and so on. However hydraulic pump is always being operated by engine or electric motor in the conventional hydraulic system. Therefore most of the conventional hydraulic system is not efficient system. Recently, an electro-hydraulic hybrid system, which combines electric and hydraulic technology in a compact unit, can be adapted to a wide variety of force, speed and torque requirements. In the electro-hydraulic hybrid system, hydraulic pump is operated by electric motor only when hydraulic power is needed. Therefore the electro-hydraulic system can reduce the energy consumption drastically when compared to the conventional hydraulic systems. This paper presents a new kind of hydraulic load simulator which is composed of electro-hydraulic hybrid system. Disturbances in the real working condition make the control performance decrease or go bad. QFT controller is designed to eliminate or reduce the disturbance and improve the control performance of the electro-hydraulic load simulator. Experimental results show that the proposed controller is verified to apply for electro-hydraulic hybrid system with varied external disturbances.

A Study on the Shock Characteristics in the Hydraulic Power Shifting System of the Hydraulic Travel Motor (유압주행모터의 변속시 발생하는 충격특성에 관한 연구)

  • Lee, Joo-Seong;Lee, Kye-Bock
    • Journal of the Korean Society of Industry Convergence
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    • v.4 no.3
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    • pp.305-310
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    • 2001
  • Hydraulic power shifting systems of hydraulic travel motor may be far safer than mechanical power transmission systems. Thus, hydraulic power shifting systems are widely used for speed control on the hydraulic equipments. In the case of liquid shifting lines, the rapid change of area, such as valve closing, can result in a large pressure transient. It is necessary to assure proper control method in order to obtain the smallest shift shock. This study conducts the shock characteristics of hydraulic power shifting system of the hydraulic travel motor. Experimental results show that shock pressure depends on the operating pressure, flow rate and pipe line area. The shock characteristics can be applied for reducing shocks.

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