• 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.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.581-584
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• 2008

At the inlet and outlet differential pressure and The fluid velocity over 32m/s are damaged (Plug, sheet ring, trim) About reduction trim parts of the control valve. AOV of the differential pressure 1,500psi become often the damage in the nuclear power plant. Damages of AOV studied CFD analysis and improvement program. Multi-stage trim designs which decrease a fluid kinetic energy are demanded and AOV parts are demanded case hardening and material change.

• 한국자동차공학회논문집
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• 제3권6호
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• pp.123-133
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• 1995

An injection control valve(ICV) was designed to control the fuel flow between a common rail and an injector with two commercial solenoids. To improve the performance of ICV, the characteristic method was applied. With this method, the flow characteristics in the ICV and the injector were studied and the parameters which affect the injection characteristics were also studied. From this study, following results were obtained. The injection duration can be controlled and with modifications of the effective valve stroke of ICV, the injection quantity and duration can be reduced to desired amount. Also the injection quantity and pressure can be controlled by reducing the hole size of the injector without the variation of the injection duration. For some conditions, the desired injection characteristics can be obtained by the changes of the valve timing, the effective valve stroke, the open pressure of the injector and the hole size of the injector.

• 한국공작기계학회논문집
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• 제16권5호
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• pp.41-47
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• 2007

The structure of ER valve is simple that its designing and manufacturing are easy. The flow rate and pressure of ER fluids flowing in the ER valve are controlled only by electric field. In this study a three port ER valve is designed and manufactured. Then, the flow rate and pressure dorp of ER fluids flowing in the ER valve are measured. The system proposed controls flow rate and pressure fast. So, this system can be easily substituted for the existing hydaulic and pneumaitc control system.

• 드라이브 ㆍ 컨트롤
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• 제17권4호
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• pp.87-96
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• 2020

In this study, a variable elasticity spring was applied to improve the pressure control precision of conventional relief valves. The equilibrium equation of the forces acting on the valve poppet was derived; it is demonstrated that matching the elastic rate of the pressure-adjusting coil spring to the equivalent elastic rate of the flow force improved the pressure override. The procedures that were used to design the variable elasticity spring are presented, and some applications of the variable elasticity spring are also introduced. Computer simulations were used to analyze three cases: a poppet-closed flow force structure, a poppet-open flow force structure with a constant elasticity spring, and a structure containing a variable elasticity spring. It is confirmed that the pressure control precision of the relief valve can be significantly improved upon by applying a variable elasticity spring to the poppet-open flow force structure.

• 유공압시스템학회논문집
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• 제8권4호
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• pp.9-16
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• 2011

Because of the increasing demand on the high precision and high response of a machinery, proportional control valves are widely adopted at various application fields. This paper studies on the static and dynamic characteristics of a pilot proportional pressure control valve. An experimental apparatus including hydraulic pump, variable speed inverter, pressure and flow sensors and data aquisition system was set up. And various experiments such as P-Q-V curves, step responses due to input voltage and flow rate, hysteresis, frequency response of the proportional valve was carried out and the results are discussed.

• 유공압시스템학회:학술대회논문집
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• 유공압시스템학회 2010년도 춘계학술대회
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• pp.18-24
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• 2010

Because of the increasing demand on the high precision and high response of a machinery, electronic control valves are widely adopted at various application fields. This paper studies on the static characteristic of a first-stage proportional pressure control valve. At first an experimental apparatus including hyd. pump variable speed inverter, pressure and data aquisition system was setted up with the experimental apparatus, various tests such as P-Q-W test, hyd, pump, dynamic, static, frequency response test of the proportional valve was carride out and the results are discussed.

• 드라이브 ㆍ 컨트롤
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• 제16권4호
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• pp.32-37
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• 2019

Glove valves are used for various purposes in the process control field because such valves enable easy control of temperature and pressure. However, such valves are associated with significant loss of pressure and also have the disadvantage of complicating the shape of the cage or plug to facilitate linear flow rate change. In this paper, the shape of the plug, one of the valve flow control elements, was designed to improve the flow characteristics of the glove valve, and then CFD analysis was performed using compressible fluid. The numerical analysis results of the glove valve were analyzed according to the opening ratio and the pressure ratio of the valve. From these results, it was found that the proper notch on the side of the plug contributed to reducing the energy loss of the fluid through the valve and improving the linearity of the valve.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.462-466
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• 1997

Proportional directional control valves (PDCVl adjust the amount of flow as well as flow direction in response to an electrical signal. This valves includes direct operated valves with or without spool position feedback. This paper investigates if it is possible to control pressure of fluids by means of the PDCV. A pressure signal is feed back to the Proportional-Integral (PI) controller, which is based upon a personal computer (PC). The PI control algorithm is implemented in a graphical programming language of LabVIEW. The results of experiments show the PDCV can be used a multi function valve of pressure control as well as direction control.

• 대한기계학회논문집
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• 제18권3호
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• pp.738-750
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• 1994

The load-sensing hydraulic system which was developed to improve energy efficiency of conventional hydraulic systems has its own properties. The instability of system responses, linearity of a servo valve, robustness for variation of external load, and dynamic interference between hydraulic motors are such properties which have much to do with control properties of the system. The load-sensing hydraulic system has instability tendancy because the load-sensing mechanism makes a positive feedback loop between the motor part and the pump part. A flow property of the servo valve can be said to be linear because the flow through the valve has nothing to do with a load pressure and the flow is strictly proportional to a valve opening which is adjusted by a valve command signal. The resultant control property can be said to be robust because the steady-state control performance is independent to the load actuated on the motor shaft. In the case when one pump simultaneously drives more than two hydraulic motors, the pump outlet pressure is determined by a hydraulic motor of the largest load pressure among all of the hydraulic motors, and, thus, the other motors are dominated by the largest load pressure. That is, the other motors can be said to be interfered by the motor of the largest load pressure.