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속도와 주행거리 변화에 따른 엔진 밸브와 시트 인서트의 마모 연구
홍재수(Jae Soo Hong),전경진(Keyoung Jin Chun),김재학(Jae Hak Kim),김양수(Yong Su Kim),김덕영(Deog Yeong Kim),임정규(Jeoung Kiu Im) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.5_1
Engine valve and seat insert wear is one of the most important factors affecting engine performance. Due to higher demands on performance and the increasing use of alternative fuel, engine valves and seat inserts are challenged with wear problems of more significant magnitude than in the past. In order to overcome such problems, a simulator has been developed to generate and control high temperatures and various speeds during motion. The wear simulator is considered to be a valid simulation of the engine valve and seat insert wear process with various speeds during engine activity.<br/> This work focuses on the various degrees of wear at three different singular test speeds (10㎐, 25㎐ & multi-㎐) as well astwo different cycle numbers (2.1×10^6 & 6.0×10^6). Throughout all tests performed in this study, the temperature of the outer surface of the seat insert was controlled at 350℃ and the test load was 1960N. It was found that higher speeds(25㎐) cause a greater degree of wear than lower speeds (10㎐) under identical test conditions (temperature, valve displacement, cycle number and test load). Although test cycle numbers were increased three times, the wear depths were not proportionally increased. Wear occurred rapidly in the initial stages of the test and the wear depths increased less significantly with each cycle number. It is shown that the wear depth of the 2.1×10^6 cycle number test at 25㎐ is much larger than that of the 6.0×106 cycle number test at 10Hz in both the valve and seat insert. Therefore, this result shows that speed (㎐) might affect wear to a greater extent than mileage (cycle number) in the valve and seat insert while the engine is running. Adhesive wear, shear strain and abrasive wear could be observed in the wear mechanisms of valves. Furthermore, adhesive wear, surface fatigue wear and abrasive wear could be observed in the wear mechanisms of seat insert.