• 한국정밀공학회지
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• 제17권8호
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• pp.165-171
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• 2000

In this study the 4-way spool valve characteristics are clearly defined and clearly defined and proposed new type of spool valve. This paper presents governing equations of the flow through clearances between sleeve and spool as a model of orifice flow for null characteristics analysis and programmed analysis software of it. This software is possible to basically analysis that not only which case of open center closed center or critical center but _ -displacement of spool lab position boundary region and spool opening of the valve and to estimate the pressure variation in the spool and external leak flow variation. We are convinced that the scale of load pressure difference is changed as lab condition of valve and this scale is changed with boundary point on the annular clearance. It is vary useful to designer and user of spool valve with this design data and analysis software.

• 한국전산구조공학회논문집
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• 제30권3호
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• pp.239-248
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• 2017

솔레노이드 밸브는 구조에 따라 스풀 밸브와 포핏 밸브로 구분된다. 구조가 단순하고 오염에 민감한 스풀 밸브에 대하여 연구가 많이 진행되고 있는 반면 오염에 덜 민감하고 장시간 작동에 용이한 포핏 밸브는 구조가 복잡하여 여전히 많은 연구가 필요하다. 포핏 밸브를 설계하기 위해서 고려해야 하는 사항으로 포핏의 직경, 포핏의 각도, 디스크의 지름, 스프링 강성, 스프링 예하중, 유로 구조 등 다양한 설계변수가 있다. 기존 연구에서는 설계변수를 한가지로 선정하여 연구가 진행되었고, 설계변수가 포핏 밸브의 유동특성에 미치는 영향에 대한 연구가 부족하다. 본 논문에서는 3/2Way 솔레노이드 밸브용 포핏 밸브의 설계변수 변화에 따른 유동특성의 변화를 분석하였다. 포핏 밸브의 설계변수 선정은 선행연구된 사례와 초기모델해석결과를 참고하여 진행하였다. 그리고 설계변수에 따른 최대압력, 최소압력, 압력강하의 영향을 평균분석(ANOM)을 사용하여 살펴보았다. 향후 3/2Way 솔레노이드 밸브용 포핏 밸브를 설계할 때 주효과를 파악하여 설계변수 선정에 사용하면 효율적인 설계변수 선정이 가능할 것으로 예상된다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.1211-1212
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• 2011

• Tribology and Lubricants
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• 제29권5호
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• pp.275-285
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• 2013

The Reynolds equation is commonly used to investigate the lubrication characteristics of a spool valve. However, the applicability of the Reynolds equation is questionable for analyzing a spool valve because cavitation often occurs in the grooves of the valve and the depth of a groove is much higher than the clearance in most cases. In this study, the validity of the Reynolds equation in the spool valve analysis is investigated by comparing the results obtained from the Reynolds equation and those obtained from the Navier-Stokes equation. The results are compared in terms of the lateral forces, friction forces, and volume flow rates (leakages). A significant difference of more than 20% is found in the lateral forces in cases where cavitation occurs and there are many grooves. Therefore, the Navier-Stokes equation should be used to investigate the lubrication characteristics of a spool valve when cavitation occurs and when the spool valve contains many grooves.

• Tribology and Lubricants
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• 제29권3호
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• pp.149-159
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• 2013

In this research, the lubrication characteristics of spool valves with various cross-sectional groove shapes were studied. The validity of using the Reynolds equation for the analysis of spool valves with various groove shapes was also investigated. The cross-sectional shapes for the grooves included a triangle, square, and U shape. The characteristics of the flow in the groove were investigated using streamlines. When the number of grooves was increased, the difference between the results obtained from the Reynolds equation and those obtained from the Navier-Stokes equation increased according to the groove shape. Thus, it was found that the Navier-Stokes equation should be used to investigate the lubrication characteristics of the spool valves in those cases. Moreover, in the case where the cross section of the groove was U-shaped, the groove prevented the small eddy current from occurring in the groove. Therefore, the lateral force and friction force of the spool valve with the U-shaped groove were lower than those of the spool valves with other groove shapes.

• 드라이브 ㆍ 컨트롤
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• 제14권1호
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• pp.14-22
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• 2017

Flow force is the additional unbalanced force acting on the valve spool by fluid flow, excluding the static pressure force that is offset on the spool land wall at the same magnitude. When designing the valve spool, it is assumed that the same average value of static pressure is applied to the inlet and outlet spool land wall in one chamber. However, the high velocity of the fluid flow by the inlet or outlet metering orifice creates unbalanced pressure distribution and generates additional force in the opposite direction to that of the solenoid attraction force. This flow force has a negative effect on the control performance of the EPPR valve, which needs to develop uniform output pressure along the entire spool control range. In this study, we developed a 3D model of the EPPR valve and conducted flow force characteristic analysis using CFD S/W (ANSYS FLUENT). The alleviated flow force model was derived by adjusting the design parameters of the spool notch.

• Tribology and Lubricants
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• 제28권5호
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• pp.218-232
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• 2012

In a spool valve analysis, the Reynolds equation is commonly used to investigate the lubrication characteristics. However, the validity of the Reynolds equation is questionable in a spool valve analysis because cavitation often occurs in the groove and the depth of the groove is much higher than the clearance in most cases. Therefore, the validity of the Reynolds equation in a spool valve analysis is investigated by comparing the results obtained from the Reynolds equation and the Navier-Stokes equation. Dimensionless parameters are determined from a nondimensional form of the governing equations. The differences between the lateral force, friction force, and volume flow rate (leakage) obtained by the Reynolds equation and those obtained by the Navier-Stokes equation are discussed. It is shown that there is little difference (less than 10%), except in the case of a spool valve with many grooves where no cavitation occurs in the grooves. In most cases, the Reynolds equation is effective for a spool valve analysis under a no cavitation condition.

• 한국항공우주학회지
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• 제34권3호
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• pp.74-80
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• 2006

본 논문은 선형 전기모터가 유압밸브 스풀(valve spool)을 직접 움직이는 직접구동밸브 (DDV: direct drive valve) 방식 유압서보 엑츄에이터의 제어 및 고장 모니터링에 관한 것이다. 유압서보 구동장치는 밸브 스풀을 통한 유량 흐름 특성으로 인하여 비선형 운동 특성을 갖게 된다. DDV 구동장치에 관한 비선형 운동 모델을 제시하고, 이를 선형화 시켜 DDV 구동장치의 제어계 및 고장 감지계 설계에 유용하게 사용될 수 있는 단순화된 선형 모델을 제시하였다. 한편, 조종면 구동 엑츄에이터가 만족시켜야 하는 성능 그리고 안전 작동에 관한 요구조건에 대하여 논의한 후, 이를 만족시키기 위한 제어계 및 고장 감지계의 구조에 대한 논의를 한다. 3중의 다중화 구조를 갖는 유압 DDV 구동장치의 운동 특성을 해석할 수 있는 수치해석 모델이 개발되었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.121-126
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• 2001

In this study, the 4-way spool valve characteristics are clearly defined and proposed new type of spool valve. This paper presents governing equations of the flow through clearances between sleeve and spool as a model of orifice flow for null characteristic analysis, and programmed analysis software of it. This software is possible to basically analysis that not only which case of open center, closed center or critical center but +,- displacement of spool, lab position, boundary region and spool opening of the valve, and to estimate the pressure variation in the spool and external leak flow variation. We are convinced that the scale of load pressure difference is changed as lab condition of spool valve, and this scale is changed with boundary point on the annular clearance. It is vary useful to designer and user of spool valve with this design data and analysis software.

• 드라이브 ㆍ 컨트롤
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• 제15권4호
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• pp.61-66
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• 2018

Almost every hydraulic system is equipped with a pressure relief valve, to maintain working pressure of the system at a pre-determined level. Thus, dynamic characteristics of such a relief valve, in conjunction with other hydraulic components, are important in designing the hydraulic control system. The single stage pressure relief valve is dynamically undesirable, due to relatively low viscous damping, that causes high frequency oscillations. This problem is overcome by introducing orifices in the inner pilot line, and drain line. In this study, for the single stage spool type pressure relief valve, the system equations were derived through an adequate linearisation and several simplifications were made, to use the transfer function formulation technique. All coefficients were evaluated and used, to make some results by using Matlab software. Results of analysis are compared with experimental results. In this study, parameters affecting stability of valve design are determined and suggested relative to the design.