EHA 펌프용 피스톤 슈 정압베어링의 경계 마찰 성능 개선

Abstract

The pumps of electro-hydrostatic actuators operate most frequently in boundary lubrication speed range, as they compensate for the position control errors as a control element. When conventional swash plate type piston pumps are applied to electro-hydrostatic actuators, the frictional power losses as well as the wear rate of sliding components, such as piston shoes can increase drastically under the boundary friction condition. In this paper, the power losses of the piston shoes were investigated which were engendered by a frictional solid-to-solid contact and leakage flow rate of their hydrostatic bearing. In order to reduce them, DLC-coating was applied to the swash plate and the ball joint of pistons along with its effects were demonstrated. In addition, it was also shown that the wear rate of the piston shoes could be markedly reduced using the DLC-coated swash plate. * Corresponding author: yshong@kau.ac.kr 1 Aerospace & Mechanical Engineering, Korea Aerospace University, Goyang-si, Gyeonggi-do 412-791, Korea 2 Aerospace & Mechanical Engineering, Graduate School, Korea Aerospace University, Goyang-si, Gyeonggi-do 412-791, Korea 3 Yoowon Industries LTD., Busan 604-030, Korea Copyright C 2014, KSFC This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License(http:// creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 기호 설명  : Balance ratio  : Inclination angle of swash plate, deg  : Piston diameter, mm  : Recess diameter, mm  : Piston shoe diameter, mm  : Friction force on piston, N  : Lift force on piston shoe, N  : Normal load on piston shoe, N  : Cylinder pressure, bar  : Recess pressure, bar  : Recess ratio()