유압 서보 액추에이터의 주 고장 모드 분석 및 수명 개선에 관한 연구

이용범(Y. B. Lee) 유공압건설기계학회 2017 유공압건설기계학회 학술대회논문집 Vol.2017 No.5

The hydraulic servo actuator has operated very precisely with high frequency and small displacement, and it used for a long time continuously. Recently, the hydraulic servo actuator of the test equipment which is utilized in the accelerated life test in order to guarantee the service life of the automotive parts has failed earlier than the products before finishing the test. This study performed the analyzing the cause of the failure mode of the hydraulic servo actuator used in the test equipment, changed the design of the actuator to solve the root cause of the main failure mode, and developed the improved servo actuator. Based on above process, this study found out the better performances and longer lifetime of the servo actuator after testing.

유압서보 액추에이터의 주 고장모드 분석 및 수명개선에 관한 연구

이용범(Yong-Bum Lee),정동수(Dong-Soo Jung),이기천(Gi-Chun Lee),강보식(Bo-Sik Kang),이종직(Jong-Jik Lee) 유공압건설기계학회 2018 드라이브·컨트롤 Vol.15 No.4

The hydraulic servo actuator has always operated very precisely with high frequency and small displacement, and is used continuously for a long time. The hydraulic servo actuator of the test equipment used in the accelerated life test in order to guarantee the service life of the automotive parts failed earlier than the products before finishing the test. This study performed an analysis on the cause of the failure of the hydraulic servo actuator used in the test equipment, changed the design of the actuator to solve the root cause of the main failure mode, and developed the improved servo actuator. Based on above process, this study established a better performances and longer lifetime of the servo actuator after testing.

발전소의 스팀제어용 유압서보 액추에이터의 공기배출 밸브에 관한 연구

이용범(Yong Bum Lee),이종직(Jong Jik Lee) 대한기계학회 2016 大韓機械學會論文集B Vol.40 No.6

원자력 발전소와 화력 발전소에서는 양질의 전기를 생산하기 위해서는 발전기에 연결된 고압 및 저압 증기터빈에 최적량의 증기를 공급하여야 한다. 터빈에 증기를 공급하거나 차단하는 특수한 밸브인 터빈출력제어장치를 사용하고 있으며, 이 터빈출력제어장치는 유압서보 액추에이터로 구동 된다. 발전소에서는 유압시스템에서 생성되는 기체로 인하여 유압서보 액추에이터의 성능이 저하되거나, 생성된 기체가 압축되면서 발생하는 열로서 씰을 태우고 마모를 증가시켜서 빈번한 고장이 유발된다. 일부 발전소에서는 고정형 오리피스를 사용하여 공기를 배출하고 있지만 많은 유량배출에 따른 동력 손실과 빈번하게 작동되는 펌프, 전기모터 및 밸브 등의 고장을 발생시킨다. 본 연구에서는 기존의 고정형 오리피스와 같이 초기에 많은 량의 공기를 배출하고 정상운전에서는 매우 미세한 유량만 통과 시킬 수 있는 부하 감응형 공기 배출밸브를 모델링하고 해석하여 장착함으로서 유압서보 액추에이터의 제어 정밀성 확보와 기체 압축으로 인한 고장을 방지할 수 있게 하였다. To produce adequate electricity in nuclear and thermal power plants, an optimal amount of steam should be supplied to a generator connected to high- and low-pressure steam turbines. A turbine output control device, which is a special steam valve employed to supply or interrupt the steam to the turbine, is operated using a hydraulic servo actuator. In power plants, the performance of servo actuators is degraded by the air generated from the hydraulic system, or causes frequent failures owing to an increase in the wear of the seal. This is due to the seal being burnt as generated heat using the produced compressed air. Some power plants have exhausted air using a fixed orifice, and thus they encounter power loss due to mass flow exhaust. Failures are generated in hydraulic pumps, electric motors, and valves, which are frequently operated. In this study, we perform modeling and analysis of the load-sensing air-exhaust valves, which can be passed through very fine flow under normal use conditions, and exhaust mass flow air at the beginning stage as with existing fixed orifices. Then, we propose a method to prevent failures due to the compressed air, and to ensure the control accuracy of hydraulic servo actuators.

유압식 구동장치의 서보밸브 오프셋 보정 방법에 관한 실험적 연구

반준혁 사단법인 유공압건설기계학회 2019 드라이브·컨트롤 Vol.16 No.2

Despite the development of electronic components and microprocessors, hydraulic actuators are still being applied in various applications. In some applications, there is a desire to apply a hydraulic actuator with a relatively small position error to the system. Various studies have been conducted to reduce the position error of hydraulic actuators. In this paper, the position error of the hydraulic actuator when the hydraulic oil pressure is supplied is defined as the offset generated by the servo valve, and the method for correcting the servo valve offset has been studied. A method for compensating the servo valve offset was proposed and it was verified through experiments that the position error of the hydraulic actuator was reduced. We also compared the servo valve offset correction method and controller using the PID control and disturbance observer used to reduce the position error of the hydraulic actuator. No-load test and load test were performed to confirm the performance of the servo valve offset correction method. The results of the study were compared with those obtained by using the disturbance observer and PID control.

공차 및 시험조건을 고려한 회전익 항공기용 유압식 구동기 MCV의 성능 경계 조건

박형준(H. J. Park),주춘식(C. S. Joo),주태우(T. W. Joo),박설혜(S. H. Park),정정래(J. G. Jeong),김대현(D. H. Kim) 유공압건설기계학회 2019 유공압건설기계학회 학술대회논문집 Vol.2019 No.11

The hydraulic actuator is used to perform flight control of the rotorcraft. The most important role for the overall performance of the hydraulic actuator is a main control valve(hereafter MCV) installed in the hydraulic actuator. To meet the overall performance requirements of hydraulic actuators, MCV performance must be defined first. The MCV of the hydraulic actuator performs a matching process in order that performance can be within defined boundary conditions after part machining. This MCV matching process meets final performance not only by machining but also by highly skilled expert. In this paper, we introduce the method of establishing the performance boundary condition of MCV for the hydraulic actuator MCV matching process considering the machining tolerances and test conditions.

전기-유압 액추에이터를 이용한 굴삭기 에너지 절감에 관한 기초 연구

윤홍수(Hong Soo Yoon),안경관(Kyung Kwan Ahan),이병룡(Byung Lyong Lee),강종민(Jong Min Kang),김재홍(Jae Hong Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11

Today, hydraulic systems play an important role in modern industry for the reasons that hydraulic actuator systems take many advantages over other technologies with high durability and the ability to produce large forces at high speeds. In recent years, electro-hydraulic actuator systems, which combine electric and hydraulic technology into a compact unit, have been adapted to a wide variety of force, speed and torque requirements. Moreover these systems resolve energy consumption and noise problems characteristic existed in the conventional hydraulic systems. Therefore, these systems have a wide range application fields especially in an excavator. So the purpose of this paper is to demonstrate efficiency of the energy saving and present some control algorithms which apply to electro-hydraulic actuator system in the bucket of the excavator. Experiments are carried out to verify the effectiveness of the proposed system with various external loads as in real working conditions.

유압액추에이터용 U자형 시일의 해석 및 실험적 고찰

유명호(Myung-Ho Yoo),이택성(Taek-Sung Lee),권종호(Jong-Ho Kwon) Korean Society for Precision Engineering 2006 한국정밀공학회지 Vol.23 No.12

Seals are usually made from elastomer, a kind of rubber, and it has the non-linearity and hyper-elasticity. U-type seals are used to prevent the leakage of internal fluid sealed in hydraulic actuator because they have more excellent performance than O-rings or rectangular seals. As a core part of hydraulic actuator, U-type seal gives much effect on performance and reliability of actuator. This study considers an NBR U-type seal under high pressure of a hydraulic actuator, and provides its deformation, stress-strain characteristic and contact force using the non-linear finite element analysis. Analysis results are compared with the experimental ones performed by the self-developed testing equipment. Verification result shows that this study presents a good application process for the effective design of U-type seals under high operation pressure.

틸팅 부하메커니즘 특성 분석을 위한 유압식 부하특성 평가 장치구성에 대한 연구

이준호(Lee, Jun-Ho),김호연(Kim, Ho-Yeon),한성호(Han, Seong-Ho) 한국소음진동공학회 2011 한국소음진동공학회 논문집 Vol.21 No.12

In this paper a configuration of the load evaluation device for the tilting actuator using hydraulic power is presented, which makes it possible to measure the force action on the tilting actuator. It is possible to measure only current using the conventional electro-mechanical actuator when the bogie is in the process of the tilting. This makes impossible to measure the force acting on the tilting actuator. In order to overcome this problem a kinetic mechanism test system using hydraulic cylinder is proposed. The system are consisted of hydraulic cylinder for the tilting actuation, control system to control hydraulic power, sensors to measure for force and displacement and monitoring system for the user interface.

발전소 스팀제어용 유압서보 액추에이터의 씰 수명 향상에 관한 연구

이용범,이종직 사단법인 유공압건설기계학회 2018 드라이브·컨트롤 Vol.15 No.2

The power plants use turbine output control devices to supply or shut off steam to high pressure and low-pressure steam turbines connected to generators. This turbine output control device is driven by a hydraulic servo actuator. The gas flows into the hydraulic servo actuator during periodic inspection or normal operation, and the resulting adiabatic compression of the gas raises the internal temperature of the actuator to 500 ℃. This temperature increase causes the seals to burn and show wear and tear, resulting in failure. In this study, an air vent valve was installed to allow gas inside the hydraulic servo actuator to flow large quantities of air at the beginning of the operation and after the periodic inspection. Gas was passed through for only minute flow during normal operation of the power plant. By applying the air vent valve, it improves the reliability of the hydraulic servo actuator by discharge the gas appropriately to improve the life of the seal.

MCV 오리피스 면적 구배 보상 기법을 활용한 비대칭형 유압식 구동기 성능 개선 설계

박차렴(Charyeom Park),김상석(Sangseok Kim),김대현(Daehyun Kim),김상범(Sangbeom Kim),박상준(Sangjoon Park) 한국항공우주학회 2016 한국항공우주학회 학술발표회 논문집 Vol.2016 No.4

본 논문에서는 직구동 제어밸브(DDV)를 적용하는 비대칭형 유압식 구동기에 대해 MCV(주제어밸브) 오리피스 면적 구배 보상 방법을 활용하여 성능 및 동특성을 개선하는 설계 기법을 연구하였다. 일반적으로 유압식 서보 구동기는 Spool/Sleeve 구조 내부에 오리피스 면적이 균일한 서보제어밸브가 채택되고 있으며, 항공기 장착시 인터페이스 및 중량을 고려하여 비대칭형 실린더를 갖는 구동기가 주로 적용되고 있다. 이러한 비대칭형 실린더를 적용하는 구동기는 실린더 챔버 내 압력 불균형(Pressure Jump) 및 동일한 용량의 서보제어밸브를 갖는 대칭형 구동기 대비한 속도 성능 저하를 유발한다. 이러한 문제를 개선할 수 있는 비대칭형 유압식 구동기의 설계 기법을 찾기 위해, 관련된 수학적 모델식을 세우고 밸브 및 피스톤의 변위에 대한 폐루프 제어를 구현하여 성능해석을 수행하였다. 또한, 비대칭형 구동기의 MCV 오리피스 면적 구배 보상 여부에 따른 성능해석 결과를 비교 분석하여 제안된 설계 기법의 적합성을 검토하였다. In this paper, a design technique that improves performances and dynamic characteristics of the asymmetric hydraulic actuator with direct drive valve(DDV) by use of compensation method of orifice area gradient is addressed. Generally, servo control valves with uniform orifice area in spool/sleeve are applied to hydraulic servo actuator and asymmetric cylinder is mainly used considering interface and weight when assembled in aircraft. But, those cause pressure jump in cylinder chamber and degradation of velocity when compared with symmetric actuators. To find a design technique of asymmetric hydraulic actuator which solves and improves those problems, the performance analysis is conducted including a mathematical model and a closed-loop control of the displacement of valve and actuator piston. Also, those results are reviewed to prove appropriateness of a proposed design technique.