• 드라이브 ㆍ 컨트롤
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• 제17권4호
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• pp.54-71
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• 2020

In light of the environmental challenges, energy-saving strategies are currently under investigation in the construction industry. This paper focuses on the energy-saving method used in the hydraulic system based on independent metering (IM) technologies, which can overcome the lost energy at the main control valve of the conventional electrohydraulic servo system. By scientifically arranging the proportional valves, the IM system can individually control the flow rate of the inlet and the outlet ports of the actuators. In addition, the IMV system can be used to effectively regenerate energy under different operating modes, thereby saving more energy than conventional hydraulic systems. Therefore, the IMV system has a great potential to improve the energy efficiency of hydraulic machinery. The overall IMV system, including the configuration, proportional valve, operation mode, and the control strategy is introduced via state-of-the-art hydraulic technologies. Finally, the challenges of IM systems are discussed to provide researchers with directions for future development.

• 한국추진공학회지
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• 제10권2호
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• pp.95-101
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• 2006

펄스폭 변조방식(PWM)으로 작동되는 솔레노이드 밸브를 이용하는 연료조절장치는 값이 싸고, 크기가 작으며, 간단한 구조로 되어있다. 본 논문에서는 이러한 장점을 이용하여 PWM 솔레노이드 밸브와 차압유지밸브(CPDV)로 구성되어, 초소형 엔진에 적용 가능한 PWM 연료조절장치를 구성하였다. 수학적 모델의 확립과 시뮬레이션을 통해 시스템의 특성과 주요 파라미터에 대한 영향을 분석하였고, 시험장치를 구성하여 시험을 수행한 결과, 시뮬레이션과 일치된 결과를 얻었으며 모델의 타당성을 확인할 수 있었다. 제안된 모델은 PWM 연료조절시스템 개발에 사용될 수 있을 것이다.

• Journal of Biosystems Engineering
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• 제23권4호
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• pp.365-372
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• 1998

This study was carried out to develop a nutrient-solution mixing-and-supplying system, which used a low-cost metering device instead of expensive metering pumps and a fuzzy logic controller. A low cost and precise overflow-type metering device was developed and evaluated by testing the flow discharge for the automatic nutrient-solution mixing-and-supplying system for snail-scale hydroponic sewers. The fuzzy logic controllers, which could predict and meet the desired values of EC and supply rate of nutrient solution were developed and verified by simulation and experiment. this fuzzy logic controller, whose algorithm consists of four crisp inputs, two crisp outputs and nine rules, was developed to predict the desired value of EC and supply rate of nutrient solution and two crisp inputs, one crisp output and nine rules used to control EC to the desired values. The nutrient-solution mixing-and-supplying system showed satisfactory EC control performance with the maximum overshooting of 0.035 mS/cm and the maximum settling time of 15 minutes in case of increasing 0.7 mS/cm. also, the accuracy of the overflow-type metering device in terms of the full-scale error was 2.29% when using solenoid valve only and 0.2% when using solenoid valve and flow control valve together.

• 드라이브 ㆍ 컨트롤
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• 제16권2호
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• pp.30-35
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• 2019

EPPR (Electro-hydraulic Proportional Pressure Reducing) valves are pressure control valves. In this study, an independent metering valve (IMV), which is a combination of a spool valve opened and closed with the help of an EPPR valve, was discussed. The overall performance of the valve (IMV) was obtained by the respective modeling and simulation of the system. The valve investigated in this study is to be used for independent metering of hydraulic excavator actuator e.g. boom, arm, bucket etc. To design the model, continuity equations and force balance equations were used. The set of differential equations were then simulated in Simulink using ODE45 option in the configuration toolbox. The valve has to be able to control the flow rate going in and out of the cylinder separately, which is why the particular configuration was needed and selected.

• 동력기계공학회지
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• 제18권6호
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• pp.51-57
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• 2014

High pressure common rail injection technology has revolutionized the diesel industry. Over the last decade it has allowed engine builders to run higher injection pressures as much as above 1,300bar in order to increase engine efficiency, while reducing emissions. This common rail system has low pressure circuit which is consist of low pressure pump, cascade overflow valve and flow metering unit. The low pressure pump's purpose is to feed fuel oil to the high pressure pump. The cascade overflow valve keeps pressure in front of the metering unit constant and provides lubrication for the high pressure pump. The metering unit, known as the MPROP or fuel pressure regulator, regulates the maximum flow rate delivers to the rail. In this paper, we have investigated the performance characteristics of each components and total low pressure circuit of common rail system.

• 드라이브 ㆍ 컨트롤
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• 제15권4호
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• pp.1-10
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• 2018

Spool displacement of a direction control valve is the standard signal to measure the bandwidth frequency of the direction control valve. When the spool displacement signal is not available, it is suggested in this study to use the metering hydraulic line as an alternative way to measure - 90 degree phase bandwidth frequency of the hydraulic direction control valve. Dynamics of the hydraulic line is composed of inertia, capacitance, and friction effects. The effect of oil inertia is dominant in common hydraulic line dynamics and the line dynamics is close to a derivative action in a range of high frequency; such as a range of bandwidth frequency of common directional control valves. Phase difference between spool displacement and line load pressure is nearly constant as a valve close to 90 degree. If phase difference is compensated from the phase between valve input and pressure, compensated phase may be almost same as the phase of spool displacement that is a standard signal to measure phase bandwidth frequency of the directional control valve. A series of experiments were conducted to examine the possibility of using line pressure in to measure phase bandwidth frequency of a directional control valve. Phase bandwidth frequency could be measured with relatively high precision based on metering hydraulic line technique and it reveals consistent results even when valve input, oil temperature, and supply pressure change.

• 드라이브 ㆍ 컨트롤
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• 제11권1호
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• pp.8-13
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• 2014

Hydraulic servo valves are widely used in various fluid power systems because of their fast response and precision control. In this paper, we studied the effect of metering notch shapes and amount of their openings on the flow characteristics within the spool valve using a computational fluid dynamic (CFD) code, FLUENT. To obtain the results for more realistic operating conditions, viscous heating due to the jet flow and viscosity variation of the hydraulic fluid with temperature were considered. For two types of notch shape, streamlines, oil temperature and viscosity distributions, and variations of flow and friction forces acting on spool were showed. The flow and friction forces affected by the metering notch shapes and their openings, and oil temperature rise near metering notch was significant enough to results in the jamming phenomenon. A thermohydrodynamic (THD) flow analysis adopted in this paper can be used in optimum design of hydraulic servo valves.

• 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.

• 드라이브 ㆍ 컨트롤
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• 제15권3호
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• pp.49-56
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• 2018

Construction machinery is used to improve productivity in civil engineering work and construction work, and it is a lengthy operation, and consumes considerable fuel to cope with large loads. As a result, productivity and fuel consumption of the construction machine become the main deciding factors. In the hydraulic system of the excavator, the main control valve is the most critical position for control. The flow distribution for control performance is achieved by the metering orifice, that causes critical energy loss. To improve this, we propose a combination of a three port proportional pressure reducing valve and a poppet type flow control valve as an IMV to replace the existing spool type MCV. To validate the proposal, we analyze static characteristics by modeling mathematically, and analyze dynamic characteristics. Simulation using the AMESim software on the regeneration circuit of the boom cylinder up-down operation, verifies the energy-saving effect compared to the existing MCV when IMV is used.

• 드라이브 ㆍ 컨트롤
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• 제15권4호
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• pp.119-124
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• 2018