• 한국정밀공학회지
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• 제20권6호
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• pp.167-177
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• 2003

In this study, a mathematical nonlinear dynamic model is introduced to predict the damping force of automotive shock absorber. And 11 design parameters were proposed for the sensitivity analysis of damping force. Design parameters consist of 5 piston valve design parameters, 5 body valve design parameters and 1 initial pressure of reservoir chamber air. All of these design parameters are main design parameters of shock absorber in the procedure of shock absorber design. The simulation results of this paper offer qualitative information of damping force variation according to variation of design parameters. Therefore, simulation results of this paper can be usefully use in the design procedure of shock absorber

• 드라이브 ㆍ 컨트롤
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• 제15권2호
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• pp.46-51
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• 2018

Many research studies have been carried out related to saving energy and environmental pollution in the field of construction machinery. The best solution for reducing the related environmental pollution is to reduce fuel consumption by upgrading the energy efficiency of machinery used in this field. An efficiency upgrade in the field of construction machinery would mean minimizing the pressure loss in hydraulic pipe lines or achieving optimal operating conditions while responding to a load. One way to achieve this is to make an equivalent circuit, like an electrohydrostatic actuator, or to improve the spool type valve using the 4/3 way method. This study deals with an electrohydraulic proportional flow control valve. SimulationX software is used as a simulation tool for analyzing the dynamic characteristics. The analysis results, including the performance and characteristics of design parameters, are discussed and the validity of the theoretical analysis is also evaluated.

• 한국기계가공학회지
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• 제16권5호
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• pp.78-84
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• 2017

Compared to other types of power, hydraulic energy is the most commonly used for heavy vehicles and ships because it has fewer location and space constraints, and its controllability can be maintained even under adverse conditions. Operators have controlled a main control valve of ship winches by pushing or pulling the lever, which is directly connected to the spool. However, because of the spatial arrangement, the importance of remote control valves has emerged. In this paper, experiments of the hysteresis characteristics were performed by analyzing the remote-control valve using a valve tester and RA2300. The validity was verified by comparing with the analytical model using SimulationX as the hydraulic analysis program. This study examined the effects of the spool's notch (Non, End-mill, and Spherical) and the effects of stiffness and pre-load of the spool spring on Spool stroke, open area, and hysteresis characteristics. It is considered possible to reduce the cost and the, trial and error process in designing remote-control valves in the future.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.488-491
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• 1997

In this paper, a ncw control 'ialvc which can misc air-iraksge pneumatically and compensate pressure drop for an alrho~ st system uas proposed A new control valve called "Pneuniatic C70ntro1 Valve (PCV)" functions as a control valve to compcns;ltc prcssure in thc casc of air-leakage. by using the pure pneummatic control ofpilot pressure. Based on the sirnulation of the proposed PCY, thc experimental system was fabricaied su as to illustrate the efficient pcrformance of the proposed PCV with anti-leakage. Such good perfo~manccs of PCV in the air-hoist system are shown by the simulation. In addition, the simulation bascd design approach presented in this paper can be applied to any hydraulic or pneumatic-hydraulic system.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.725-730
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• 2011

우주발사체 추진기관 공급계에서 2-way 솔레노이드밸브는 제어시스템의 명령에 의해 추진제 탱크를 가압하여 탱크내의 압력을 조절한다. 가압용 솔레노이드밸브의 제작에 앞서 설계검증 및 기본적인 작동특성을 분석하기 위해 AMESim상용코드를 이용하여 해석모델을 수립하였다. 입구압력에 따른 작동시간을 시험결과와 비교하여 모델을 검증하였다. 솔레노이드밸브 모델을 이용하여 설계변수인 컨트롤 밸브의 시트 직경, 주 밸브의 시트 직경, 실링 직경 비에 대해 밸브의 동특성 해석을 수행하였다. 해석을 통해 밸브의 개폐작동시간, 작동성능, 개폐압력을 예상하였다. 본 연구 결과는 한국형 발사체 공급계 가압용 솔레노이드밸브의 설계/해석능력을 확보하고 밸브의 개발과정에서 효율성을 높일 수 있으며 파생형 밸브의 설계 및 선행연구에 적용할 수 있을 것으로 판단된다.

• 대한의용생체공학회:의공학회지
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• 제13권2호
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• pp.87-96
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• 1992

In thIns paper, a numerical simulation of steady laminar and turbulent flow in a two dimensional model for the total artificial heart is'presented. A trlleaflet polyurethane valve was simulated at the outflow orifice while the Inflow orifice had a trileaflet or a flap valve. The finite analytic numerical method was employed to obtain solutions to the governing equations in the Cartesian coordinates. The closure for turbulence model was achieved by employing the k-$\varepsilon$-E model. The SIMPLER algo rithm was used to solve the problem in primitive variables. The numerical solutions of the slulated model show that regions of relative stasis and trapped vortices were smaller within the ventricular chamber with the flap valve at the Inflow orifice than that with the trileaflet valve. The predicted Reynolds stresses distal to the inflow valve within the ventricular chamber were also found to be smaller wlth the flap valve than with the trlleaflet valve. These resu1ts also suggest a correlation be- tween high turbulent stresses and the presence of thrombus In the vicinity of the valves in the total artificial hearts. The computed velocity vectors and trubulent stresses were comparable with previ ously reported in vitro measurements in artificial heart chambers. Analysis of the numerical solo talons suggests that geometries similar to the flap valve(or a tilting disc valve) results in a better flow dynamics within the total artificial heart chamber compared to a trileaflet valve.

• Nuclear Engineering and Technology
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• 제54권5호
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• pp.1674-1685
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• 2022

The ball valve is an important device in the pipeline transportation system of nuclear power plants. Its operational stability and safety directly affect the normal working of nuclear power plants. In this study, the transient numerical simulation of the opening and closing process of a ball valve was conducted on the basis of the flow interruption capability experiment of the ball valve by using the moving mesh method and inlet and outlet variable boundary conditions. The flow rate and pressure difference with time of the opening and closing process of the ball valve were studied. The internal flow characteristics of the ball valve under different relative openings were analyzed in conjunction with the typical back-step flow structure. Results show that the transient numerical results agree well with the experimental results. The internal flow characteristics of the ball valve are similar at the same opening during opening and closing process. At small opening, the spool and outlet channels easily form a back-step flow structure. The disappearance and generation of backflow vortices during opening and closing occur at 85% opening and 75% opening, respectively. With the decrease in opening degree, the difference in vortex core area in the flow channel of the ball valve spool in the opening and closing process gradually appears. The research results provide some reference value for the design and optimization of ball valves.

• 한국자동차공학회논문집
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• 제4권6호
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• pp.97-108
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• 1996

A modeling technique is proposed for dynamic simulations of OHC valve trains with HLA(hydraulic lash adiuster). HLA is expressed by an air-oil mixture model considering HLA leak-down and aeraton effects. A compact nonlinear equation is derived which describe the short term dynamic behavior of the HLA. Valve spring is analyzed by a distributed parameter model including nonlinear characteristics in the spring surge phenomena. Global behavior of the remaining valve train is expressed by a lumped mass model. The experiental results prove that the simulation model developed here is accurate and useful for the dynamic simulations of OHC valve trains with HLA.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1210-1214
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• 2008

Electro-pneumatic servo valve is an electro-mechanical device which converts electric signal into pneumatic flow rate or pressure. In order to improve the overall performance of pneumatic servo systems, electro-pneumatic servo valves are required, which have fast dynamic characteristic, no air leakage at null, and can be fabricated at a low-cost. The first objective of this research is to design and fabricate a new electro-pneumatic servo valve which satisfies the above-mentioned requirements. In this paper, we has been modeled as a system consisting of coupled electro-mechanic and mechanical subsystems. The appropriateness of the model has been verified by simulation. The simulation model resolves the valve body motion and the solenoid current at high accuracy. Also, we are calculate the displacement of spool and computed results show winding currents, magnetic actuator force, flux density line, displacement, velocity, back EMF, eddy current etc.

• 한국자동차공학회논문집
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• 제11권1호
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• pp.104-111
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• 2003

The performance of shock absorber is directly related to the car behaviour and performance, both for handling and comfort. In this study, a mathematical nonlinear dynamic model and computational method are introduced to study the flow and performance of shock absorber. The flow characteristics of components(piston and body valve) are investigated and applied to dynamic modeling of shock absorber to predict the damping force. The simulation results agree with the test data well. The shock absorber model proposed in this paper is applicable as a part of a full vehicle suspension simulation.