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김성동(S. D. Kim),전세형(S. H. Jeon),주별진(B. J. Joo),윤소남(S. N. Yoon) 유공압건설기계학회 2013 유공압건설기계학회 학술대회논문집 Vol.2013 No.6
Common type of servovalves is to control flowrate measuring and diagnosis of servovalve`s hysteresis is based upon analysis of flowrate signal. The ISO 10770-1 and KS B 6511 regulations for servovalve`s hysteresis are also established from analysis of flowrate signal. The measurement of flow is hard to implement. In this study, some hysteresis diagnosis methods are investigated to use pressure signal and spool displacement signal. Three kinds of hysteresis; flowrate hysteresis, pressure hysteresis and spool displacement hysteresis are measured from an experiment set-up. Two kinds of pressure hysteresis; pressure gain hysteresis and no-load pressure hysteresis are investigated. The spool displacement hysteresis is found to be the most accurate and pressure hysteresis are also good enough as well as flow hysteresis. The pressure gain hysteresis shows a little error from other hysteresis, and it is estimated because geometric dimension error of spool and sleeve affects the hysteresis.
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.
Study on Bandwidth Frequency of Servovalve based on Metering Cylinder
S. D. Kim(김성동),Wen-Long An(안문용),S. H. Jeon(전세형) 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.
A Research on the Bandwidth Frequency of Servo Valves Based on the Dynamic Flow Rate
S. D. Kim(김성동),Wen-Long An(안문용),S. H. Jeon(전세형) 유공압건설기계학회 2015 유공압건설기계학회 학술대회논문집 Vol.2015 No.6
In this paper flow rate signal and spool displacement signal were adopted to investigate the bandwidth frequency of servo valve. Spool displacement and flow rate dynamic response experiments on different input signal and hydraulic pipe diameter were implemented. The spool displacement dynamic response remains stable throughout, so it can be received accurately reflects the authentic performance of servo valve. Meanwhile the flow rate signal is easy disturbed by hydraulic environment and deviate from the spool displacement signal in small input signal and phase lag.
유량제어용 서보밸브와 비례방향밸브의 압력신호를 이용한 정적 성능 진단에 관한 연구
김성동(S. D. Kim),전세형(S. H. Jeon),김인동(I. D. Kim),함영복(Y. B. Ham) 유공압건설기계학회 2012 드라이브·컨트롤 Vol.9 No.4
Most diagnosis methods for servo valves requires installing spool displacement sensor or flow sensor as well as pressure sensor. The measurement of flow is hard to implement and many kinds of servovalves or proportional direction valves do not have a built-in spool displacement sensor. In this study, static performances of servovalve or proportional-direction-valve are studied theoretically and a diagnosis technique, which uses only load pressure and input current signal, is assessed. An experimental setup was made based upon a personal computer and the LabVIEW graphical language. A series of diagnosis tests were performed and the analysis results showed it possible to measure the pressure gain, hysteresis and null bias in a relatively simple methodology.
김성동(S. D. Kim),전세형(S. H. Jeon),진광호(K. H. Jin) 유공압건설기계학회 2014 유공압건설기계학회 학술대회논문집 Vol.2014 No.9
In the work, it was studied to use a pressure signal instead of the flow rate and spool displacement signals to diagnose the valve dynamic performance. The mathematic model of a servo valve was derived and the model parameters were accurately identified to represent the real servo valve. A series of computer simulation works were done to measure the bandwidth frequencies to represent the dynamic property of the servo valve in closed-ports condition. When outlet ports are set to be of tiny volume, the –90〫phase frequencies of the load pressure were found to be well coincide with those of spool displacement.
유압실린더 힘 제어계의 인-프로세스 서보밸브 마모진단에 관한 연구
김성동(S. D. Kim),전세형(S. H. Jeon),장영배(Y. Chang) 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.