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유압실린더 힘 제어계의 인-프로세스 서보밸브 마모진단에 관한 연구
김성동,전세형,장영배 사단법인 유공압건설기계학회 2009 드라이브·컨트롤 Vol.6 No.2
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.
미터링 오리피스를 이용한 방향제어밸브 위상각 대역폭 주파수 측정에 관한 연구
김성동,전세형,윤주섭 사단법인 유공압건설기계학회 2018 드라이브·컨트롤 Vol.15 No.1
The spool displacement of directional control valve can be considered as the standard signal to measure the bandwidth frequency of a directional control valve. When the spool displacement is not available, the metering-orifice system is implemented in this research as an alternative way of measuring the 90 degrees phase bandwidth frequency of the hydraulic directional control valve. The inertia effect on the transmission line oil induces the phase lead of the valve load pressure when compared with the phase of spool displacement. The capacitance effect of the oil induces the phase lag of the valve load pressure. The phase of the load pressure can be adjusted to be the same as that of the spool displacement by controlling the opening area of the metering orifice. A series of experiments were conducted to verify the effectiveness of the metering orifice. The 90 degrees phase bandwidth frequency measured from the valve load pressure was significantly deviated in some cases from the frequency of the spool displacement. The metering orifice was hard to be applied to measure the –90 degrees phase bandwidth frequency of the high precision.
Study on Bandwidth Frequency of Servovalve based on Metering Cylinder
김성동,안문용,전세형 사단법인 유공압건설기계학회 2015 드라이브·컨트롤 Vol.12 No.3
In this study, a metering cylinder was constructed, and the velocity obtained from the linear velocity transducer (LVT) of the cylinder piston was used to evaluate the dynamic performance of an electro-hydraulic servovalve. Frequency response experiments involving the spool displacement and piston velocity (LVT signal) were conducted with different input signal amplitudes, hydraulic pipe diameters, and supply pressures. The spool displacement signal accurately reflected the performance of the servovalve. Meanwhile, the -3 dB bandwidth frequency of the LVT signal was similar to the spool displacement signal, except for a small-amplitude input signal, and the -90° phase lag bandwidth frequency showed some differences.
가변주파수 신호를 이용한 서보 밸브 동특성 시험에 관한 연구
김성동(S.D. Kim),전세형(S.H. Jeon),진광호(K.H. Jin) 유공압건설기계학회 2014 유공압건설기계학회 학술대회논문집 Vol.2014 No.4
Signals of flowrate and spool displacement have been used to diagnose the dynamic performance of hydraulic servovalve. however, it is hand to measure a dynamic flowrate signal which rapidly varies in a short time period. Most of servovalves do not have a bwilt-in sensors for spool displacement. In the work, it was studied to use pressure signal to diagnose servovalve’s dynamic performance instead of the flowrate and displacement signals, The bandwidth frequencies to represent the dynamic properly of servovalves were measured from an experimental set-up. The bandwidth frequencies of load pressure for current input signal were compared with those of spool displacement.
김성동(Sungdong Kim),전세형(Sehyeong Jeon),신대영(Daeyoung Shin) 유공압건설기계학회 2017 유공압건설기계학회 학술대회논문집 Vol.2017 No.5
The spool displacement of a servo valve can be considered to be the standard signal to measure the bandwidth frequency of servo valves. When the spool displacement is not available, the metering orifice system is suggested as an alternative way to measure the – 3 dB amplitude ratio bandwidth frequency of the hydraulic servo valve in this study. The amplitude ratio of the metering orifice pressure can be adjusted to be the same as that of the spool displacement by controling the opening area of the metering orifice. A series of experiments were conducted to verify the effectiveness of the metering orifice system. The metering orifice was found to be good enough to measure the – 3 dB amplitude ratio bandwidth frequency.