• 제목/요약/키워드: hydraulic dead-zone

검색결과 24건 처리시간 0.028초

유압 굴삭기 시뮬레이터 개발 (Development of Simulator for Hydraulic Excavator)

  • 임태형;이홍선;양순용
    • 유공압시스템학회논문집
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    • 제2권1호
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    • pp.9-14
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    • 2005
  • Hydraulic excavators have been popular devices in construction field because of its multi-workings and economic efficiency. The mathematical models of excavators have many nonlinearities because of nonlinear opening characteristics and dead zone of main control valve, oil temperature variation, etc. The objective of this paper is to develop a simulator for hydraulic excavator using AMESim. Components and whole circuit are expressed graphically. Parameters and nonlinear characteristics are inputted in text style. The simulator can be used to forecast excavator behavior when new components, new mechanical attachments, hydraulic circuit changes, and new control algorithm are applied. The simulator could be a kind of development platform for various new excavators.

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유압 굴삭기용 시뮬레이터 개발 및 응용 (Development and Application of Simulator for Hydraulic Excavator)

  • 임태형;양순용
    • 한국정밀공학회지
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    • 제23권9호
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    • pp.142-148
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    • 2006
  • Hydraulic excavators have been popular devices in construction fields because of their multi-workings and economic efficiency. The mathematical models of excavators have many nonlinearities because of opening characteristics and dead zone of main control valve(MCV), oil temperature variation, etc. The objective of this paper is to develop a simulator for hydraulic excavator using AMESim. Components and their circuits are expressed graphically. Also, parameters and nonlinear characteristics are considered in a text style. From the simulation results, fixed spring stiffness of MCV can not obtain the satisfactory accuracy of spool displacement under whole P-Q diagrams. Closed loop type MCV containing a proportional gain, is proposed in this paper that can reduce displacement error. The ability of closed loop MCV is verified through comparing with normal type MCV using AMESim simulator. The excavator simulator can be used to forecast the attachment behaviors when components, mechanical attachments and hydraulic circuits change, or other control algorithms are applied. The simulator could be a kind of development platform for new excavators.

Hydrodynamics and parametric study of an activated sludge process using residence time distribution technique

  • Sarkar, Metali;Sangal, Vikas K.;Bhunia, Haripada
    • Environmental Engineering Research
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    • 제25권3호
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    • pp.400-408
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    • 2020
  • Hydrodynamic study of Activated Sludge Process (ASP) is important to optimize the reactor performance and detect anomalies in the system. Residence time distribution (RTD) study has been performed using LiCl as tracer on a pilot scale aeration tank (AT) and ASP, treating the pulp and paper mill effluent. The hydraulic performance and treatment efficiency of the AT and ASP at different operating parameters like residence time, recycle rate was investigated. Flow anomalies were identified and based on the experimental data empirical models was suggested to interpret the hydrodynamics of the reactors using compartment modelling technique. The analysis of the RTD curves and the compartment models indicated increase in back-mixing ratio as the mean hydraulic retention time (MHRT) of the tank was increased. Bypassing stream was observed at lower MHRT. The fraction of dead zone in the tank increased by approximate 20-25% with increase in recycle rate. The fraction of the stagnant zone was found well below 5% for all performed experiments, which was under experimental error. The substrate removal of 91% for Chemical oxygen demand and 96% for Biochemical oxygen demand were observed for the ASP working at a hydraulic mean residence time 39 h MRT with a 20% recycling of activated sludge.

3위치 솔레노이드 벨브를 이용한 유압 조타 장치의 제어에 관한 연구 (A Study on a Control of Hydraulic Steering Gear by Using Three-Position Solenoid Valve)

  • 심성효;이학도
    • 수산해양기술연구
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    • 제34권2호
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    • pp.231-237
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    • 1998
  • Generally, the three position solenoid valve has veen used for the hydraulic steering gear on account of it’s low cost, simplicity in device, etc. But, there is some off-set because of dead-zone which exists in on-off valves. In this paper, we proposed a combined controller which was added an integral controller to an only on-off one in hydraulic steering gear control system used low speed three position solenoid valve. Experimental results show that the off-set is removed, and the number of valve switching is reduced considerable. The validity of proposed method comparing with an only on-off control was proved by the response experiments.

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청라지구 물순환체계내 주운수로의 흐름유발시설 설치효과 (The Effect of Flow Induction Machine in Water Circulation System of Cheongna Canal Way)

  • 김동언;최계운;박영식;윤근호
    • 한국수자원학회:학술대회논문집
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    • 한국수자원학회 2010년도 학술발표회
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    • pp.77-81
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    • 2010
  • This study carried out hydraulic model test for water circulation system in Cheongna district as part of Incheon Free Economic Zone. Canal way project of Cheongna was planned to establish for environment-friendly water circulation system, improve quality of life and diversification of traffic through using boat as a water-friendly international business city. The navigation canal, There are two intake facility in central park and it can purify water 15,000$m^3$ per day. After purify, water move to 8 facility of water culture area which supplies water in canal way. This process called water circulation system in cheongna. Also, there are several flow induction machine in canal way except south-north way. Therefore, this study will verify about validity of water circulation system's safety through hydraulic model test.

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유압 굴삭기용 폐루프 타입 MCV(Main Control Valve) (Closed loop type MCV(Main Control Valve) for Hydraulic Excavator)

  • 임태형;이홍선;양순용
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2005년도 춘계학술대회 논문집
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    • pp.864-870
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    • 2005
  • Hydraulic excavators have been popular devices in construction field because of its multi-workings and economic efficiency. The mathematical models of excavators have many nonlinearities because of nonlinear opening characteristics and dead zone of main control valve, oil temperature variation, etc. The objective of this paper is to develop a simulator for hydraulic excavator using AMESim. Components and whole circuit are expressed graphically. Parameters and nonlinear characteristics are inputted in text style. From the simulation results, fixed spring stiffness of MCV can't satisfy accuracy of spool displacement under whole P-Q diagrams. Closed loop type MCV containing proportional gain is proposed in this paper that can reduce displacement error. The ability of closed loop MCV is verified through comparing with normal type MCV using AMESim simulator. The simulator can be used to forecastexcavator behavior when new components, new mechanical attachments, hydraulic circuit changes, and new control algorithm are applied. The simulator could be a kind of development platform for various new excavators.

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정수지 내부 단락류 발생 평가 : Part A. 정수장 내부 단락류 분석을 통한 장폭비와 형태가 T10/T 값에 미치는 영향 연구 (Internal Short-circuiting Estimation in Clearwell : Part A. Improving T10/T Using Intra Basin and Diffuser Wall by Applying ISEM to Field)

  • 신은허;이승재;김성훈;박희경
    • 상하수도학회지
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    • 제22권1호
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    • pp.105-112
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    • 2008
  • Disinfection is a basic and effective microorganism inactivation method and historically contributed a decrease in waterborne diseases. To guarantee the disinfection ability, improving T in CT value is important. Many indexes are used to estimate the hydraulic efficiency, however, these are black-box analysis. Therefore it is need to develope new estimation method. In this study, internal short-circuiting estimation method (ISEM) is developed using CFD and we inquire into the factor which causes increase of $T_{10}/T$ value as LW ratio increases. And the effect of shape on the relation of LW ratio and $T_{10}/T$ is analyzed. As LW ratio increases, internal short-circuiting index (ISI) of influent and effluent zone is rapidly reduced and recirculation and dead zone are reduced in channel zone. Therefore, as the $T_{10}/T$ value converges maximum value, ISI curve is changed from "V" shape to "U" shape and hydraulic efficiency is improved especially in downstream portion of clearwell. The less the shape ratio(width/length of clearwell) is the less the $T_{10}/T$ value is at a same LW ratio because the portion of turning zone increases as shape ration decreases, therefore more boundary separation is generated.

Hydraulic Residence Time in a Prototype Free Water Surface Constructed Wetland

  • Lee, Kyung-Do;Kwun, Soon-Kuk;Kim, Seong-Bae;Cho, Young-Hyun;Kim, Jin-Ho
    • 한국환경농학회지
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    • 제24권1호
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    • pp.6-11
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    • 2005
  • A prototype surface flow constructed wetland was built in the upstream area of reclaimed tidal lands to improve the water quality of Lake Sihwa by treating severely polluted stream water. In this study, a tracer test using rhodamine-WT was performed to investigate the flow characteristics and to quantify the observed hydraulic residence time (HRT) for a high-lying cell in the Banwol wetland of the Sihwa constructed wetland. The tracer test indicated that even if flow was mainly observed in the open water area of the Banwol wetland, water flowed continuously in the vegetative area and there was no dead zone. The calculated HRT (51.3 hrs), calculated by dividing the wetland volume by the wetland inflow, exceeded the observed HRT (38.7 hrs), since the short-circuiting of flux resulting from irregular topography and vegetation was not reflected in the calculated HRT. The exit tracer concentration curves were reproduced well by both the plug flow with dispersion and tanks-in-series models, indicating that the performance of the Banwol wetland can be estimated accurately using these models.

건설기계용 유압실린더 위치 제어시스템의 성능개선에 관한 연구 (A study on performance improvement of position control system in hydraulic cylinder for heavy construction machinery)

  • 한석재;박성환;이진걸
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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    • pp.1450-1454
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    • 1996
  • Even though digital control type high speed solenoid valve is a little inferior to analog control type servo valve and proportional control valve in performance, it is cheap and has secure performance against pollutant and simple control circuit. But high speed solenoid valve is hardly used for heavy machinery instead of servo valve or proportional control valve that is used in severe condition because the valve itself is small capacity and it shows wide dead zone during on-off control and chattering of hydraulic cylinder by chattering of pressure. It is desirable to use low-priced and strong pollutant resistant high speed solenoid valve for obtaining reliability of operation from severe working condition because it isn't necessary to acquire response characteristic of high frequency when we consider the characteristic of heavy machinery operation. In this study, PWM control algorithm for pilot pressure control of large capacity pilot operating valve will be used for precision position control of heavy machinery hydraulic cylinder. Not only cost reduction of main control valve but also high reliability of heavy machinery in severe condition can be obtained by using this pilot operating spool valve with high speed solenoid valve.

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경사판 침전지에서 저류벽의 설치위치에 따른 수리학적 특성의 평가 (Evaluation of Hydraulic Characteristics Influenced by Different Deflector Baffles in the Sedimentation Basin with Inclined Plate Settler)

  • 유명진;김현철;류성호
    • 한국물환경학회지
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    • 제21권1호
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    • pp.40-45
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    • 2005
  • Sedimentation is one of the most common and important units in conventional water treatment plant. Structure such as various baffle walls and inclined plate settler may be obstacles to the horizontal flow when it is poorly designed. Therefore, the effects of these structures on characteristics of hydraulic flow must be evaluated to improve the settling efficiency of the floc. The hydraulic characteristic of the two sedimentations at Y water treatment plant (YWTP), which have different deflector baffles inside the settling basin, were investigated by tracer (fluoride) test. The inclined plate settler installed inside settling basin caused an undesirable impact on horizontal flow and produced dead zone. Solid baffle wall under the plate settler could help to minimize the formation of density currents and flow short circuiting. NaF used as a tracer was recovered more than 90% at investigated all basins. Morill index ($t_{90}/t_{10}$), Modal index ($t_p/T-HRT$) and short-circuiting index ($[M-HRT-t_p]/M-HRT$) were determined from tracer test results performed at YWTP. Those indices ranged 2.95~3.02, 0.40~0.53 and 0.32~0.46, respectively.