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양방향펌프와 편로드실린더에 의한 리프터의 구동에 관한 연구
이성래,김제민,Lee, Seong-Rae,Kim, Je-Min 한국자동차공학회 2007 한국 자동차공학회논문집 Vol.15 No.4
The motion of single-rod cylinder is typically controlled by the directional control valve. In some case, the hydraulic system should be energized by the man power and at the same time the motion of a cylinder is controlled manually. It may be confusing for a man to do two things at the same time. The solution is to make up the closed hydraulic circuit with the bi-directional pump and single-rod cylinder without using a directional control valve. In the case of single-rod cylinder, the flows at the rod side and head side are so different that several valves should be installed to make the motion of single-rod cylinder possible. The hydraulic system is composed of a bi-directional pump, a single-rod cylinder, pilot operated check valves, a check valve and a counter balance valve for the purpose of actuating the lifter. The characteristics of a suggested system are analysized mathematically and numerically.
이성래,Lee, Seong-Rae 대한기계학회 1996 大韓機械學會論文集B Vol.20 No.11
A transient hydraulic flow rate computation scheme is described here so that the transient hydraulic flow rate can be determined using the dynamic pressure measurements at the ends of a straight flow line with a dynamic model of the hydraulic line. This method can be applied to determine the orifice ares of high response valve. Simulation results indicate that the method is relatively robust to realistic levels of uncertainties in the fluid properties.
해석적 Bode 방법에 의한 직접구동형서보밸브의 고전적 제어기 설계
이성래,최현영,문의준,Lee, Seong-Rae,Choe, Hyeon-Yeong,Mun, Ui-Jun 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.4
Direct drive servovalve(DDV) is a kind of one-stage valve since the rotary motion of DC motor is directly transferred to the linear motion of valve spool through the link. Since the structure of DDV is simple, it is less expensive, more reliable and offers reduced internal leakage and reduced sensitivity to fluid contamination. However, the flow force effect on the spool motion is significant such that it induces large steady-state error in a step response. If the proportional control gain is increased to reduce the steady-state error, the system becomes unstable. In order to satisfy the system design requirements, the classical controller is designed using the analytical Bode method.
콤플렉스법에 의한 리프터용 폐유압회로의 정상상태 해 탐색
이성래(Seong-Rae Lee) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The closed hydraulic circuit of the lifter is composed of a bi-directional pump, a single-rod cylinder, two pilot operated check valves, two check valves and a counter balance valve, The steady state solution of a suggested hydraulic system is very difficult to find analytically due to the high nonlinearities. The steady state pressures and flow rates of the lifter hydraulic system are obtained by solving the nonlinear equations applying the complex method that is one kind of constrained direct search method.
이성래(Seong-Rae Lee) 유공압건설기계학회 2008 유공압건설기계학회 학술대회논문집 Vol.2008 No.10
The typical hydraulic hoisting system of the rack-bar type sluice gate is composed of a hydraulic supply unit, a direction control valve, a hydraulic motor, a counter balance valve, and flow control valves. Here, the hydrostatic transmission is applied to the hoisting system of rack-bar type sluice gate to simplify the operation of gate such that the motion direction of gate is simply controlled by the direction of pump rotation. The new hydraulic hoisting system is composed of a bi-directional pump, a hydraulic motor, a external pilot operated counter balance valve, two check valves, two relief valves and a restrictor. The characteristics of a suggested system are analysized mathematically and numerically.
콤플렉스법에 의한 리프터 유압회로 유량제어밸브의 최적유량계수 설계
이성래(Seong-Rae Lee) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The typical hydraulic system of lifter is composed of a hydraulic supply unit, a directional control valve, two pilot operated check valves, two flow control valves. The flow coefficients of flow control valves should be adjusted so that the lifter is operated at moderate speed and the hydraulic energy loss is minimized. However, it is difficult to adjust the four flow coefficients of flow control valves by trial and error for optimal operation. The steady state model of the lifter hydraulic system is derived and the optimal flow coefficients of flow control valves are obtained using the complex method that is one kind of constrained direct search method.