• 한국공작기계학회논문집
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• 제12권3호
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• pp.38-44
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• 2003

The solenoid valve in ABS hydraulic modulator is a two directional on-off valve and is controlled by around 100Hz high speed pulse width modulation. When the valve is switched from open state to closed state, noise and vibration due to pressure surge phenomena in the hydraulic line and wheel cylinder are made. In this study, we identify Pressure surge phenomenon in the braking process of a ABS, and investigate the way to reduce the phenomenon. For the purpose of theoretical analysis on the pressure surge in the closed state hydraulic line, characteristic curve method based on wave equation was utilized. To reduce the surge, high frequency control of 20kHz was attempted. The result showed that the surge pressure of 50% was reduced compared to one observed in the low frequency control. Duty variation of high frequency can control current of solenoid valve and prevent sudden change of displacement.

• 한국수소및신에너지학회논문집
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• 제11권3호
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• pp.107-117
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• 2000

Ball poppet valve type high pressure hydrogen injection valve actuated by solenoid has been developed for the feasibility of practical use of hydrogen fueled engine with direct injection and the precise control of fuel injection ratio in hydrogen fueled engine with dual injection. The gas-tightness of ball poppet injection valve is improved by the introduction of ball-shaped valve face, valve end typed spherical pair, and valve stem with rotating blade. Ball poppet valve is mainly closed by differential pressure due to the area difference between valve fillet and pressure piston. So, it can be operated by solenoid actuator with small driving force. From the evaluation of ball poppet injection valve, it was found that the gastightness and controlment of this injection valve are better than those of injection valve had been developed before.

• 한국자동차공학회논문집
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• 제9권2호
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• pp.130-136
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• 2001

This paper presents an of a brake pressure restriction valve to a motorcycle anti-lock brake system(ABS). In the conventional anti-lock brake system of automobiles, slip ratio as a control variable is actively controlled, which requires wheel speed sensors, ECU, and a pressure modulator. In the ABS valve that has been developed for use in motorcycles, however, the brake pressure that is close to the wheel locking pressure is preset by simple exercises and then the valve just allows to pass the wheel locking pressure and cutoff the remaining pressure. Simulation studies with a single wheel braking dynamics and lumped chassis model show that the pressure restriction valve has basic ABS functions as well as some robustness properties for the uncertain load and road conditions as well as various initial braking speeds. Field tests also show that the pressure restriction valve avoids the wheel locking effectively.

• 청정기술
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• 제11권4호
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• pp.181-188
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• 2005

밸브 내부의 입자들의 화울링 현상의 제어 및 저감을 위해 공기분사 방식을 적용하는 새로운 분립체용 볼 밸브를 개발하였다. 밸브 내부의 분립체와 분사공기 흐름간의 상호작용 및 화울링 현상에 대한 규명을 위해 전산유체역학적 해석을 수행하였고, 해석결과들을 밸브 형상 및 공기분사 조건 설계에 반영하였다. 설계된 분립체용 볼 밸브의 실제 시험을 통해, 본 볼 밸브가 여러 운전 조건들에 대해서 우수한 화울링 저감효과를 가짐을 알 수 있었다.

• 한국가시화정보학회지
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• 제19권1호
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• pp.12-17
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• 2021

A three-dimensional slope valve component is used for controlling micro volume of liquid on a centrifugal force-based microfluidic disk platform, also called a lab-on-a-disk. The modeling factor of the slope valve component is determined to centrifugal force for liquid passing the crest of a slope valve via variation of slope length and angle as well as the radius to start point of slope valve. The centrifugal force is calculated by the equilibrium equation of the capillary and gravitational forces according to the microchannel surface roughness and the liquid volume, respectively. As a result, the slope valve is analyzed by the minimum angular velocity for liquid passing at crest point and the ratio between the length of micro liquid and slope length to obtain the factors for optimal slope angle modeling.

• 드라이브 ㆍ 컨트롤
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• 제18권1호
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• pp.17-23
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• 2021

The flow signal or spool position signal is used to determine the dynamic characteristics of directional control valves. Alternatively, the signal of spool position or flow can be replaced with the velocity of a low friction, low inertia actuator. In this study, the frequency response of the servo valve equipped with a spool position transducer is measured with a metering cylinder. The input signal, spool displacement, load pressure, and velocity of the metering cylinder are measured, and the theoretical results from the transfer function analysis are verified. The superposition rule for magnitude ratio and phase angle was found to be always applicable among any signal type, and it was found that the load pressure signal is not appropriate for use as the signal for measuring the frequency response of a servo valve. It was confirmed that the frequency response of a servo valve using metering cylinder was similar to the results from a spool displacement signal. The metering cylinder used for measuring the frequency response of a servo valve should be designed to have sufficiently greater bandwidth frequency than the bandwidth frequency of the servo valve.

• 대한기계학회논문집A
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• 제21권3호
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• pp.485-501
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• 1997

Pressure control is possible driving a simple ON/OFF 3-way valve of hydraulic servo system by pulse width modulation signal. But the pressure varies according to the duty ratio and carrier frequency and repeated on-off action induces pressure fluctuation. So equations for mean pressure and ripple amplitude are theoretically derived as a function of on/off time, the system parameters which decide the pressure characteristics are arranged and they are verified by experimental study. As the result selection criteria for the major design parameters are established and the basic strategy to suppress the unnecessary fluctuation can be provided for a hydraulic pressure control system using these type of valves.

• 한국자동차공학회논문집
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• 제4권4호
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• pp.80-86
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• 1996

In order to decrease fuel comsumption rate and emissions, lean burn engine which has equipped swirl control valve, is investigated experimentally on the test bench. Single cylinder engine was used to test the combustion and emission performance with 4 kinds of swirl valve. Decrease in the carbon monoxide, hyerocarbon and specific fuel consumption was shown at the lean condition, which means that a good choice of swirl valve on the given intake port geometry can be used to increase the combustion efficiency and lean limit.

• International Journal of Air-Conditioning and Refrigeration
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• 제12권3호
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• pp.131-140
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• 2004

The purpose of this research is to derive the principal design parameters governing the dynamic characteristics of the high response flow control servo valve. For this purpose, a numerical modeling of the servo valve system and a parameter sensitivity analysis to a frequency response characteristics were performed. As a result of these analysis, a basis for improvement of a dynamic characteristics of servo valve was arranged.

• 한국산학기술학회논문지
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• 제17권2호
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• pp.137-146
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• 2016

EGR율이 증가할수록 $NO_X$ 저감에는 효과적이나, 과도한 EGR율은 오히려 불완전 연소의 주원인이 된다. 엄격한 배기규제를 만족하기 위해서는 엔진의 운행 조건에 최적화된 정밀한 EGR 밸브의 위치 제어가 뒷받침 되어야 한다. 따라서 본 연구에서는 EGR 밸브 용 모터 특성 분석을 위해 수학적 모델링과 제어 이론에 대해 연구하고, 마이크로칩 개발 툴을 이용하여 EGR 밸브용 모터의 위치를 제어하기 위한 단계로서 PWM(Pulse Width Modulation)의 듀티(duty)비의 입력 값에 따른 밸브 위치를 측정하여 개폐 구간 별 EGR 밸브 모터 특성을 분석하였다.