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세계 건설기계 산업의 패러다임은 지속적으로 변화하고 있다. 2010년도 초반에는 고유가의 영향으로 하이브리드 또는 전기식 건설기계가 이슈가 되더니 2015년 이후에는 스마트기술이 채택한 반자율/자율건설기계가 개발 중심에 서있다. 건설기계의 대표 기종인 굴삭기도 특정 작업에 대해 반자동화와 완전자동화가 가능한 MC(machine control)기술을 개발하고 있다. 일반적으로 굴삭 작업은 붐 실린더와 암 실린더와 버켓 실린더의 변위와 힘이 붐과 암 그리고 버켓을 통하여 최종적으로 버켓 끝단에서 특정 작업을 하게 된다. 문제는 붐과 암 그리고 버켓을 가공한 후에 가공치수를 측정하면 항상 가공편차 편차가 존재한다. 각 실린더의 변위가 동일하더라도 붐과 암 그리고 버켓의 가공편차는 버켓 끝단의 자세가 상이하며 최악의 경우에는 특정 작업을 할 수 없을 정도로 버켓 끝단의 자세가 불량할 수 있다. 본 연구에서는 도랑 작업에서 붐과 암 그리고 버켓의 가공편차에 따른 버켓 끝단의 자세를 통계적으로 분석하였다. 향후에 정밀작업이 가능한 굴삭기에서 통계적 분석을 바탕으로 설계인자의 공차를 결정하는데 도움이 될 수 있다.
This paper presents the analysis on the proportional pressure control valve with large capacity for industrial use. Some theoretical and numerical analysis wa performed to design the proportional solenoid valve and a code has been developed for caculation for solenoid valve. To do this, analytical and numerical method was used. After several analysis, a real part for solenoid valve. To do this, analytical and numerical method was used. After several analysis, a rel part for solenoid valve are manufactured and some experiment for assembled solenoid valve was performed. The experiment reults show that the results from the developed program comes to nearly that of experiment.
This research deals with the development of digital type servocontroller for proportional flow control valve based on the functional analysis of commerical analog type positioner. In addition to all the functions that are implemented in conventional controller, it is designed with some useful facilities such as LVDT output signal auto calibration, self-performance test with embedded function generator and remote control and monitoring, etc. Moreover, optional open-loop and current control mode can be utilized to design a proportional integral position controller gain together with the system identification of plunger dynamics. Hence, those design features not only enable the easy and simply calibration, but also ensure the reliable operation with the optimal system parameter setup. The control performance of valve position and versatile utility functions are tested and verified with experiments. For the next year, it will advanced to the on-board diagnosis and fail-safe functions for smart valve system.
Over the years, electromagnetic control valve, which utilize magnetic force for the modulation of pilot valve, has replaced the air-operated valve(AOV) and motor-operated valve(MOV) by virtue of advanced technology for solenoid design. Its superior operating characteristics and packless design make it favorable to be applied in most demanding applications such as nuclear and chemical plants. This paper deals with the steady-state characteristics of proportional flow control valve which regulates the large amount of high pressure fluid with two stage valve design. The main disc follows the pilot disc by the differential pressure that is changed with self-controlled system. The pilot pressure of control chamber, pilot flow and relative displacement of main disc to pilot disc at steady-state are investigated and the effect of main disc area ratio on the control characteristics is analyzed.
The poppet valve had used every field area due to high quality of leakage property and response characteristic. But this valve still has terrible disadvantage that is self-exited vibration. This problem affects stability of total system and raises noise. The researcher tries to reduce that self-exited vibration when valve was designed. The stability discriminant is the typical study to improve the performance of the poppet valve. This paper concerns about stability discriminant that uses poppet valve with a drain orifice. At the first, the mathematical model is computed from poppet valve. After that, the limitation of stability is calculated that based on Nyquist criterion. At the final, the stability discriminant is selected in each condition and the graph that shows stability in the system is drown by dimensionless quantity.
Hydraulic cylinder is one of many part on the hydraulic excavator working. Cushion has the important function of protecting cylinder against the shock when the piston comes at end position. Also, the cushion of cylinder has a great effect on the operator"s comfortable. In this study, we have done a comparative analysis through computer simulation and experimental value on pressure that occurs on a cylinder moving excavator.
Semi-active cabin air suspension system improves driver"s comfort by controlling the damping characteristics of cabin suspension system continuously or discretely in accordance with driving situation. A field test method of evaluating the ride performance of the system has a drawback. It requires a lot of time and money on repetitive test, due to the sensitivity of field test. On the other hand, the test with multi axial hydraulic vibration system can obtain the repeatability of test, better than the field test method. In this paper, the procedures of ride performance test and control logic tuning with the table are presented. Drive files of the table can be represented with the almost same input condition as field test data.
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 Multi-stage 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-V-Q 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.
Direct Drive Valves (DDV) with electric closed loop spool position control are suitable for electrohydraulic position, velocity, pressure or force control systems including those with high dynamic response requirements. The spool drive device is a permanent magnet linear force motor which can actively stroke the spool from its spring centered position in both directions. This basic study is carried out to drive the design parameters for developing a domestic DDV. The static and dynamic characteristics of DDV are examined. The simulation results are compared with data of manufacture"s catalog to show the validity of the modelling.