Tribology and Lubricants

Korean Tribology Society (한국트라이볼로지학회)
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Wear Analysis of Journal Bearings in a Misaligned Shaft During Motoring Start-up and Coast-down Cycles - Part I: Study on the Change in Oil Film Thickness at Potential Wear Regions

모터링 시동 및 시동정지 사이클에서 경사진 축을 갖는 저어널 베어링의 마모 해석 - Part I: 마모발생 가능영역에서의 유막 변화 연구

  • Chun, Sang Myung (School of Mechanical Engineering, Dept. of Automotive Engineering, Hoseo University)
  • 전상명 (호서대학교 기계공학부 자동차공학전공)
  • Received : 2017.06.19
  • Accepted : 2017.08.04
  • Published : 2017.08.31
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Abstract

The aim of this study is to find the change in trend in the eccentricities of two journal bearings supporting the crankshaft of a single cylinder engine and the degree of misalignment of the shaft. We analyze the change in oil film thickness considering the wear scar under mixed-elasto-hydrodynamic lubrication regime at potential wear regions. For this, we first calculate the central eccentricities of the two journal bearings by using the mobility method. Then we calculate the outer end eccentricity by using the geometry of the bearings. Further, the tilting angle and degree of misalignment of the shaft are calculated by using the eccentricities of the two bearings. We show that the eccentricity of bearing #1, on which higher load is applied, increases at the beginning of the start-up cycle and during the coast-down cycle. However, the eccentricity of bearing #2, on which lower load is applied, decreases at the beginning of the start-up cycle and increases during the coast-down cycle. From the results of the analysis of oil film thickness, we show that the mixed-elasto-hydrodynamic lubrication regime for a misaligned shaft is at the initial stages of the start-up cycle for both bearing #1 and #2 and at the final stage of the coast-down cycle for only bearing #1.

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References

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