• Title/Summary/Keyword: hydraulic constant

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Constant Frequency Control of Generating System Driven by Hydraulic Power - Simulation - (유압 구동식 발전장치의 정주파수 제어 - 시뮬레이션 -)

  • Jeong, Yong-Gil;O, In-Ho
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.26 no.3
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    • pp.275-281
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    • 1990
  • This study suggests a new type shaft generator driven by hydraulic power suitable for small size vessels. Since the shaft generator system is very easy to be affected by disturbances such as speed variation of the main engine and the load variation of the generator, a robust servo control must be performed to obtain stable electric power with constant frequency. So, in this study the robust servo control method is adopted to the controller design. Dynamic characteristics on the frequency variations of the electric power output according to the disturbances are investigated by computer simulations. From the considerations of the computer simulation results, it is ascertained that the shaft generator system proposed in this study had good control performances.

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Pressure Control Valve using Proportional Electro-magnetic Solenoid Actuator (비례솔레노이드 액추에이터를 이용한 압력제어밸브)

  • Ham Young-Bog;Park Pyoung-Won;Yun So-Nam
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.30 no.10 s.253
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    • pp.1202-1208
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    • 2006
  • This paper presents an experimental characteristics of electro-hydraulic proportional pressure control valve. In this study, poppet and valve body which are assembled into the proportional solenoid were designed and manufactured. The constant force characteristics of proportional solenoid actuator in the control region should be independent of the plunger position in order to be used to control the valve position in the fluid flow control system. The stroke-force characteristics of the proportional solenoid actuator is determined by the shape (or parameters) of the control cone. In this paper, steady state and transient characteristics of the solenoid actuator for electro-hydraulic proportional valve are analyzed using finite element method and it is confirmed that the proportional solenoid actuator has a constant attraction force in the control region independently on the stroke position. The effects of the parameters such as control cone length, thickness and taper length are also discussed.

A Kinematic Analysis on Piston Rod Mechanism in Swashplate Type Hydraulic Axial Piston Motor/Pump Using Constant Velocity Joint (등속조인트를 적용한 사판식 유압 모터/점프의 로드형 피스톤에 대한 운동해석)

  • Kim K.H.;Kim S.D.;Ham Y.B.;Lee J.C.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.2 no.1
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    • pp.1-8
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    • 2005
  • Recently, swash plate type hydraulic axial piston motors/pumps are being extensively used in the world, because of simple design, light weight and effective cost. Structural problem of the swash plate type motor/pump is that tilting angle of swash plate should be limited to relatively small value and lateral farce on pistons has an undesirable effect in reciprocating motion. To solve these problems, piston rod mechanism, which is commonly used in bent axis type motor/pump, is considered to be applied to the swash plate type motor/pump. In this paper, kinematic analysis was done on the piston rod mechanism. A series of formula were derived and numerical calculations were done for a set of motor parameters.

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Spherical cavity expansion in overconsolidated unsaturated soil under constant suction condition

  • Wang, Hui;Yang, Changyi;Li, Jingpei
    • Geomechanics and Engineering
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    • v.29 no.1
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    • pp.1-11
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    • 2022
  • A semi-analytical solution to responses of overconsolidated (OC) unsaturated soils surrounding an expanding spherical cavity under constant suction condition is presented. To capture the elastoplastic hydro-mechanical property of OC unsaturated soils, the unified hardening (UH) model for OC unsaturated soil is adopted in corporation with a soil-water characteristic curve (SWCC) and two suction yield surfaces. Taking the specific volume, radial stress, tangential stress and degree of saturation as the four basic unknowns, the problem investigated is formulated by solving a set of first-order ordinary differential equations with the help of an auxiliary variable and an iterative algorithm. The present solution is validated by comparing with available solution based on the modified Cam Clay (MCC) model. Parametric studies reveal that the hydraulic and mechanical responses of spherical cavity expanding in unsaturated soils are not only coupled, but also affected by suction and overconsolidation ratio (OCR) significantly. More importantly, whether hydraulic yield will occur or not depends only on the initial relationship between suction yield stress and suction. The presented solution can be used for calibration of some insitu tests in OC unsaturated soil.

Analysis of Hydraulic Characteristics of High Pressure Injector with Piezo Actuator (피에조 액츄에이터 적용 고압 인젝터의 유압 동특성 해석)

  • Lee, Jin-Wook;Min, Kyoung-Doug
    • Transactions of the Korean Society of Automotive Engineers
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    • v.14 no.4
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    • pp.164-173
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    • 2006
  • In the electro-hydraulic injector for the common rail Diesel fuel injection system, the injection nozzle is being opened and closed by movement of a injector's needle which is balanced by pressure at the nozzle seat and at the needle control chamber, at the opposite end of the needle. In this study, the piezo actuator was considered as a prime movers in high pressure Diesel injector. Namely a piezo-driven Diesel injector, as a new method driven by piezoelectric energy, has been applied with a purpose to develop the analysis model of the piezo actuator to predict the dynamics characteristics of the hydraulic component(injector) by using the AMESim code. Aimed at simulating the hydraulic behavior of the piezo-driven injector, the circuit model has been developed and verified by comparison with the experimental results. As this research results, we found that the input voltage exerted on piezo stack is the dominant factor which affects on the initial needle behavior of piezo-driven injector than the hydraulic force generated by the constant injection pressure. Also we know the piezo-driven injector has more degrees of freedom in controlling the injection rate with the high pressure than a solenoid-driven injector.

Digital adaptive control of electro hydraulic velocity control system (전기.유압 속도제어 시스템의 디지탈 적용제어에 관한 연구)

  • 장효환;전윤식
    • 제어로봇시스템학회:학술대회논문집
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    • 1988.10a
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    • pp.321-325
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    • 1988
  • The objective of this study is to develop a microcomputer-based adaptive controller for an electro hydraulic velocity control system subjected to the variation of system parameters. The step response performance of the system with the adaptive controller is investigated for the variation of the external load torque, the moment of inertia and the reference inputs, and compared with that obtained by PID controller whose gains are constant. The experimental results show that this proposed model reference adaptive controller is robust to the variation of system parameters and yield much better control performance compared with the conventionel PID controller.

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Analysis of Mount Reaction Forces for Powertrain Mounting Systems using Nonlinear Characteristics (비선형 특성을 적용한 파워트레인 마운팅 시스템의 마운트 전달력 해석)

  • Kim, J.H.;Lee, S.J.;Lee, W.H.;Kim, J.R.
    • Journal of Power System Engineering
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    • v.12 no.2
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    • pp.23-28
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    • 2008
  • The primary objective of this study is to truly understand reaction force be due to engine exciting force. Exciting forces of the engine apply a source of the vehicle NVH(Noise, Vibration, Harshness). To understand reaction force was applied MSC.Nastran software. Analyzed frequency response analysis of powertrain mount system. First, engine exciting force was applied field function. Also nonlinear characteristics was applied field function : such as dynamic spring constant and loss factor. And nonlinear characteristics was applied CBUSH. Generally characteristics of rubber mount is constant frequency. But characteristics of hydraulic mount depend to frequency. Therefore nonlinear characteristics was applied. Powertrain mounting system be influenced by powertrain specification, mount position, mount angle and mount characteristics etc. In this study, we was analyzed effects of powertrain mounting system. And we was varied dynamics spring constant and loss factor of mounts.

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Decolorization kinetics and characteristics of the azo dye acid red 18 in MSBR system at various HRTs and SRTs

  • Zonoozi, M. Hasani;Moghaddam, M.R. Alavi;Maknoon, R.
    • Membrane and Water Treatment
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    • v.5 no.4
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    • pp.281-293
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    • 2014
  • The present work aimed to study the decolorization kinetics and characteristics of a selected azo dye under the influence of two key operational parameters including hydraulic retention time (HRT) and solid retention time (SRT). The decolorization efficiency and the two important criteria of k and normalized k (k/MLSS) were evaluated in lab-scale membrane sequencing batch reactors (MSBRs) at various HRTs of 48, 24 and 16 h (with constant SRT) and in addition, at various SRTs of infinity, 40 and 10 d (with constant HRT). According to the obtained results, both zero and first-order kinetics were properly fitted the decolorization profiles of the selected azo dye in all of the applied HRTs and SRTs. Increase of both HRT and SRT positively affected the decolorization efficiency. More MLSS concentrations corresponded to the lower HRTs and the higher SRTs resulted in higher decolorization rate constants (k). However, the effect of reducing the HRT was not compensated by increase of the MLSS concentration in order to reach higher decolorization efficiency. In addition, increase of the decolorization efficiency, as a consequence of the higher MLSS concentrations at longer SRTs, was restrained by decrease of the time-limited decolorization capability of biomass (represented by normalized k). Evaluation of both k and normalized k is suggested in order to have a more precise study on the decolorization kinetics and characteristics.

Electronic-hydraulic Hitch Control System for Agricultural Tractor -Draft Control- (트랙터의 전자유압식(電子油壓式) 히치 제어(制御) 시스템에 관한 연구(硏究)(II) -견인력제어(牽引力制御)-)

  • Yoo, S.N.;Ryu, K.H.;Yun, Y.D.
    • Journal of Biosystems Engineering
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    • v.14 no.4
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    • pp.229-241
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    • 1989
  • The purposes of this study were to develop an electronic-hydraulic draft control system for tractor implements, to investigate the control performance of the system and the possibility of adaptation to the conventional tractor. Experiments were carried out to investigate the responses of the system to the step and sinusoidal inputs in draft control. The effects of control mode, hydraulic flow rate, reference deadband, and proportional constant on control performance of the system were investigated. Moreover, the effects of filtering signals from draft sensor were also investigated. The following conclusions were derived from the study; 1. In draft control, there were hunting problems in controlling the implement without filtering the draft signals. Filtering was performed by a control program of electronic controller and the control performance and stability of the system were improved significantly. 2. For the draft control system operated on on-off control mode, draft was controlled within ${\pm}27-{\pm}55kg_f$ to the reference draft when the hydraulic flow rates were 5-15 l/min. For the draft control system operated on PWM control, draft was controlled within ${\pm}27kg_f$ to the reference draft regardless of hydraulic flow rates. 3. In the frequency responses of the draft control system, control performance on PWM control mode was not better than on on-off control mode because of characteristics of hydraulic valve and drafe sensor. As the hydraulic flow rates increased for the system operated on on-off control mode, the corner frequency of amplitude attenuation increased, but the corner frequency of phase-angle change remained nearly the same. But, the system was unstable beyond the frequency of 3.1 rad/s. 4. The electronic-hydraulic hitch control system developed in this study showed superior control performance, stability and convenience compared to conventional mechanical-hydraulic hitch control system. It is considered to be a superior replacement for the conventional mechanical-hydraulic hitch control system.

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Dynamic Analysis of Single-Effect/Double-Lift Libr-Water Absorption System using Low-Temperature Hot Water (저온수를 이용하는 일중효용/이단승온 리튬브로마이드-물 흡수식 시스템의 동적 해석)

  • Kim, Byong-Joo
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.21 no.12
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    • pp.695-702
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    • 2009
  • Dynamic behavior of Libr-water absorption system using low-temperature hot water was investigated numerically. Thermal-hydraulic model of single-effect/double-lift 100 RT chiller was developed by applying transient conservation equations of total mass, Libr mass, energy and momentum to each component. Transient variations of system properties and transport variables were analysed during start-up operation. Numerical analysis were performed to quantify the effects of bulk concentration and part-load operation on the system performance in terms of cooling capacity, coefficient of performance, and time constant of system. For an absorption chiller considered in the present study, optimum bulk concentration was found to exist, which resulted in the minimum time constant with stable cooling capacity. COP and time constant increased as the load decreased down to 40%, below which the time constant increased abruptly and COP decreased as the load decreased further.