• International Journal of Safety
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• 제11권2호
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• pp.10-14
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• 2012

Recently, the combined power plants are refocused rapidly as a replaceable energy system of the nuclear power plant. The large turbine is revolved highly at 1800~3600 rpm. Thus, the turbine speed should be monitored with mechanical and electrical method for a safety. The electrical cutoff valve which blocks the flow channel with the electrical signal is with a built in. The aim of this study is to develop a manufacturing technology through by the localization of a solenoid actuated directional control valve. Especially the results show performances of the solenoid valve by the experiments and modeling and the reliability estimation. Applied load port pressure was changed rapidly on the form of a quadratic curve over time. And in the cases of square waveform when 0~100 V and 20~120 V input voltage, it was driven on a stable state until 13.4 Hz and 16.6 Hz, respectively. We think that this study will give useful data for the electricity safety system of the combined power plant gas turbine.

• 드라이브 ㆍ 컨트롤
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• 제15권4호
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• pp.131-138
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• 2018

• 드라이브 ㆍ 컨트롤
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• 제16권4호
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• pp.56-64
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• 2019

Recently, as the environmental regulation for earth moving equipment has been tightened, advanced systems using electronic control have been introduced for energy savings. An IMV(Independent Metering Valve), which consists of four 2-way valves, is one of the electro-hydraulic control systems that provides more flexible controllability and potential for energy savings in excavators, when compared to the conventional 4-way spool valve system. To fully realize an IMV, a two-stage bi-directional flow control valve which can regulate the large amount of flow in both directions, should be developed in advance. A simple design that allows proportional flow control to apply the pilot pressure from the current-controlled solenoid to the spring loaded flow control spool and thus valve displacement, is proportional to the solenoid current. However, this open-loop type valve is vulnerable to flow force which directly affects the valve displacement. Force feedback servo of which the position loop is closed by the feedback spring which interconnects the solenoid valve and flow control spool, could compensate for the flow force. In this study, linearity for the solenoid current input and robustness against load pressure disturbance is investigated by linear analysis of the static nonlinear equations for the IMV proportional flow control valve with feedback spring. Gains of the linear system confirm the performance improvement with the feedback spring design.

• 드라이브 ㆍ 컨트롤
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• 제15권4호
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• pp.39-47
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• 2018

Recently, as environmental regulations for earth-moving equipment have been tightening, advanced systems such as electronic control, have been introduced for energy savings. An IMV (Independent Metering Valve) consisting of four 2-way valves, is an electro-hydraulic control systems that provides more flexible controllability, and potential for energy savings in excavators, when compared to the conventional 4-way spool valve system. To fully maximize use of an IMV, the bi-directional flow control valve that can regulate a large amount of flow in both directions, should be adopted. The hydraulic circuit of an IMV applied to an excavator from an overseas construction equipment company, reveals the flow control valve with the compound of proportional solenoid valve for first stage, and 2-way spool valve for the second stage. Moreover, the two spools are interconnected by a feedback spring, presumed to compensate for flow force acting on the second stage spool. This paper addresses the static analysis of flow control valve in an IMV to investigate the improvement of robustness, against flow force by the feedback spring. From the steady-state analysis of flow control valve model, it can be concluded that the feedback spring facilitates maintaining linearity of spool displacement for control input, and relatively constant flow for load disturbance.

• 한국기계가공학회지
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• 제4권4호
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• pp.39-47
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• 2005

In this paper, a novel high power micropump using active check valves in place of conventional passive check valves employed at the inlet and outlet ports is presented. It actively controls open/close motion of check valves using piezoelectric actuator for expansion/contraction of pump chamber. A prototype micropump having an effective size of $17mm{\times}8mm{\times}11mm$ is fabricated. Frequency-dependent flow rate characteristics, bi-directional flow characteristics and load characteristics are experimentally investigated using a timing control method for valve closing motion. From the obtained experimental results, it is ascertained that optimal values of the phase shift compared to the voltage to drive pump chamber are $15^{\circ}$ for inlet check valve and $195^{\circ}$ for outlet. Based on the obtained results, a sheet-type active shuttle valve that has a unified valve-body for inlet and outlet check valves is proposed. A micropump with an effective size of $10mm{\times}10mm{\times}10mm$ is fabricated and the basic characteristics are experimentally investigated.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1864-1869
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• 2003

A novel piezoelectric micropump using active check valves in place of conventional passive check valves in inlet and outlet has been proposed and investigated. It actively controls open/close motion of check valves using piezoelectric actuator for expansion/contraction of pump chamber. In this paper, bi-directional flow characteristics and load characteristics are experimentally investigated using an adequate timing control for valve closing motion with a prototype micropump fabricated with the effective size of $17{\times}8{\times}11mm^{3}$. From the experimental results, it is ascertained that optimal values of phase shift against voltage to drive pump chamber for realization of a miniaturized but powerful micropump, are $15^{\circ}$ in inlet check valve and $195^{\circ}$ in outlet. Based on the obtained results, a sheet-type active shuttle valve that has a unified valve-body for inlet and outlet check valves is proposed. A micropump with the effective size of $10{\times}10{\times}10mm^{3}$ is fabricated and basic characteristics are experimentally investigated.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1225-1230
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• 2007

The turnover-type sluice gate is typically actuated by the hydrauic system. The hydraulic system may be a open circuit type or a closed circuit type. The open circuit type hydraulic system is composed of a uni-directional pump, a directional control valve, pilot operated check valves, flow control valves, single-rod cylinders. The closed circuit type hydraulic system is composed of a bi-directional pump, pilot operated check valves, check valves, a counter balance valve, single-rod cylinders. The energy efficiencies of two hydraulic systems for the turnover-type sluice gate are compared here.

• 유공압시스템학회논문집
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• 제6권2호
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• pp.14-21
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• 2009

The typical hydraulic hoisting system of the rack-bar type sluice gate is composed of a hydraulic supply unit using an uni-directional pump, 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 upward and downward 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, two counter balance valves, two check valves, two pilot-operated check valves, two relief valves and a shuttle valve. The characteristics of a suggested system are analyzed by computer simulations.

• 유공압시스템학회논문집
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• 제5권1호
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• pp.13-19
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• 2008

The typical hydraulic system of hoist is composed of a hydraulic supply unit, a directional control valve, counter balance valve, and flow control valves. The flow capacity coefficients of flow control valves should be adjusted so that the hoist is operated at moderate speed and the hydraulic energy loss is minimized. However, it is difficult to adjust the flow coefficients of flow control valves by trial and error for optimal operation. Here, the steady state model of the hoist hydraulic system including the differential cylinder circuit is derived and the optimal flow capacity coefficients of flow control valves are obtained using the complex method that is one kind of constrained direct search method.

• 한국항공우주학회지
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• 제35권3호
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• pp.231-237
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• 2007

EHA용 유압 펌프의 토크 맥동은 저속 회전 영역에서 실린더 위치의 제어에 외란으로 작용할 수 있다. 원칙적으로 피스톤 펌프에 의해 발생되는 반력 토크의 주기적인 변화는 실린더 압력의 파형과 밀접한 관계를 가지고 있다. 일정 속도로 회전하는 단방향 피스톤 펌프의 경우에는 밸브 플레이트의 예압각이나 노치를 활용하여 실린더 압력의 오버슈트나 변화율을 조절할 수 있다. 따라서 본 연구에서는 밸브 플레이트의 형상이 EHA용 사축식 유압 피스톤 펌프의 토크 맥동에 미치는 영향을 분석하였다. 그 결과로서, 양방향 회전형 유압 피스톤 펌프의 토크 맥동은 회전 속도의 영역에 무관하게 밸브 플레이트의 예압각이나 노치를 이용하여 개선하는 것이 불가능한 것으로 나타났다.