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Kim K.H.;Han G.S.;Lee J.C.;Ham Y.B.;Kim S.D.
- Transactions of The Korea Fluid Power Systems Society
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- v.1 no.2
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- pp.1-7
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- 2004
In-process diagnosis is essential to achieve predictive maintenance in industrial plants. An in- process diagnosis method was proposed for hydraulic servo systems, which was based upon leakage flow measurement. Leakage due to servovalve wear was analysed and modeled mathematically far computer simulation work. The key idea of diagnosis algorithm is that when monitoring signals, such as servovalve input and load displacement are in steady states, the return-line flow of hydraulic servo systems can be regarded as null-leakage of servovalve. Virtual experiments were performed to ensure effectiveness of the proposed diagnosis method.
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Kim, S.D.;Jeon, S.H.;Chang, Y.
- Transactions of The Korea Fluid Power Systems Society
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- v.6 no.2
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- pp.22-30
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- 2009
An in-process method of diagnosing the spool wear of hydraulic servovalves was explored. The diagnostic method discussed in this paper is for force-control hydraulic servo systems. The key principle used is that pressure sensitivity of a servovalve drops as the valve spool wears out so that it is possible to determine the spool condition by monitoring pressure sensitivity. A diagnostic algorithm was developed and evaluated through numerical simulation and experiments. Two major steps of diagnosis are the evaluation of null bias of the servovalve and the approximation of pressure sensitivity, both of which could be successfully done during normal operation of a servo system. The difference between a new servovalve and a worn valve could be clearly detected in-process, and the diagnostic test was found to be repeatable.
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Lee, Hyung-Don;Bae, Hyung-Sub;Lee, Yuk-Hyung;Park, Myeong-Kwan
- Journal of Institute of Control, Robotics and Systems
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- v.17 no.9
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- pp.888-891
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- 2011
This paper presents development of flow control valve using MR fluid. Generally, since the apparent viscosity of MR fluids is adjusted by applying magnetic fields, the MR valves can control high level fluid power without any mechanical moving parts. In this paper, flow control valve using MR fluid on the behavior of the magnetic field influence on the numerical analysis of more accurate electromagnetic parameters were obtained, even if when magnetic field apply inside of surrounding MR fluid from electromagnet, more realistic designing way analysis of characteristic of whole magnetic field distribution is suggested by surrounding magnetic material. Also, comparison of flow rate inlet and outlet, behavior of MR fluid in experiments proposed. A new type of flow control valve using MR fluid is proposed by analysis of behavior of MR fluid in experiments.
https://doi.org/10.5302/J.ICROS.2011.17.9.888 인용 PDF KSCI

Kim, D.C.;Lee, J.K.;Kang, Y.S.;Lee, J.C.
- Transactions of The Korea Fluid Power Systems Society
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- v.6 no.3
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- pp.10-15
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- 2009
The major system of an agricultural power-shift tractor is the transmission, using power-shift. Because the transmission performance depends on the hydraulic control system, the most important aspect of the optimization is the design of the hydraulic control system. This study was conducted to improve a pressure modulation characteristics of the power-shift transmission hydraulic system. It has been tried to replace an existing pressure modulation method with a digital control by using HSSV(High Speed Solenoid Valve). The performance of the PWM control system in power-shift hydraulic transmission has been evaluated by means of experiment.
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