• Title/Summary/Keyword: Oil film analysis

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A Study on the Stability of Geared Systems Subjected to Torsional and Lateral Instability (비틀림진동 및 행진동을 받는 기어시스템의 안정화에 관한 연구)

  • Ro, S.H.
    • Journal of the Korean Society for Precision Engineering
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    • v.7 no.3
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    • pp.103-114
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    • 1990
  • Many high speed mechanical systems incorporate gearing for speed reduction. This study investigates the stability of mulit-rotor geared systems supported on oil film bearings taking into consideration the coupling between torsional and lateral dynamics. The emphasis of the study is on the analysis of the interaction between the combined torsional and whirl insta- bilities. The feasility of inducing a lateral and the torsional instability to neutralize an anticipated unstable condition is investigated. The possibility of suppressing the instabilities by controlling the parameters of the oil film bearings is also considered.

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An Analysis of Performance of Floating-Ring Journal Bearing Including Thermal Effects (유막의 온도변화를 고려한 플로팅 링 저어널베어링의 성능해석)

  • 김종수;최상규;유광택
    • Tribology and Lubricants
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    • v.17 no.2
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    • pp.130-137
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    • 2001
  • In this paper, the thermal effects on the performance of floating ring journal bearing are investigated theoretically. The numerical analyses include pressure drop at inner film due to a centrifugal force, fluid momentum effects of supply oil into inner film and thermal effects in lubricating films. All performance data are presented as the rotating speed of journal from 10,000 rpm to 70,000 rpm.

An Engine Structure-Borne Noise Analysis by Finite Element Method (유한요소법에 의한엔진 구조소음 해석)

  • 안상호;김주연;김규철
    • Transactions of the Korean Society of Automotive Engineers
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    • v.6 no.1
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    • pp.122-133
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    • 1998
  • This paper presents the static analysis, the modal analysis and the forced vibration analysis on engine structures to find out the structure-borne noise sources by finite element method. The deformation of engine structures under the maximum combu- stion gas force was calculated through the static analysis, and the resonance possibilities were predicted by the modal analysis which ascertains mode shapes and the corresponding frequencies of engine global and its major noise sources in engine surfaces were investigated with the forced vibration analysis by means of finding the transfer mobilities on engine surfaces due to the piston impact and the velocity levels due to the combustion in consideration of oil film stiffness and damping coefficients. Finally, the direction of engine structure-borne noise reduction can be estabilished by the above-mentioned analysis procedure and the reduction effect of cost on proto-type engine build-up is expected.

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Surface Roughness Effects on the Lubrication Characteristics of the Engine Piston Ring Pack

  • Yun, Jeong-Eui
    • KSTLE International Journal
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    • v.1 no.2
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    • pp.83-90
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    • 2000
  • The surface roughness between a piston ring pack and a cylinder liner directly affects the fuel economy, the oil consumption, and the emission of the engine so that it is very important to clarify the surface roughness effects on the lubrication characteristics. The friction characteristics of the piston ring during engine operations are known to as mixed lubrication experimentally. In this study to simulate the effects of the surface roughness of the piston ring pack on the lubrication characteristics, the mixed lubrication analysis of piston rings was performed using the simplified average Reynolds equation. From the results the surface roughness was found be considerably affects minimum oil film thickness as well as FMEP(Friction Mean Effective Pressure). Especially, the oil ring was the most sensitive on the surface roughness.

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Pin-Boss Bearing Lubrication Analysis of a Diesel Engine Piston Receiving High Combustion Pressure (고 연소압을 받는 디젤엔진 피스톤의 핀-보스 베어링 윤활해석)

  • Chun, Sang-Myung;Ha, Dae-Hong
    • Tribology and Lubricants
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    • v.24 no.3
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    • pp.133-139
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    • 2008
  • In recently designed diesel engines, the running conditions for piston pin bearings have become very severe due to combustion pressure and temperature increase. In this paper, it will be investigated the tendency of piston pin rotating motion by calculating the friction coefficient at piston pin bearings, the oil film thickness and the frictional torques induced by hydrodynamic shear stress. Finally, the pressure distributions on the oil film of piston pin bearings will be found by two-dimensional lubrication analysis in order to help the optimum design of the bearings of piston pin. Specially, it is investigated the effects on the film pressure distribution due to the change in maximum combustion pressure.

윤활유 첨가제에 따른 마멸분 화상해석

  • 서영백;이충엽;박홍식;전태옥
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1998.04a
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    • pp.180-189
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    • 1998
  • This paper was undertaken to do shape analysis of wear debris on oiliness agent and extreme pressure agent. The lubricating wear test was performed under different experimental conditions using the wear test device was made in our laboratory and were- specimens of the pin on disk type was rubbed in paraffine series base oil by materials, varying applied load, sliding distance, oil additives such as stearine acid, DBDS, TCP. The four shape parameters (50% volumetric diameter, aspect, roundness and reflectivity) on a kind of the additives are different on applied load and sliding distance and Its are affected by absorbed film and reaction film. DBDS and TCP have a role of extreme pressure agent but a role of absorbed film of stearic acid decrease in high load. The maximum wear volume on applied load be in existence in three kinds of the specimens because of reaction characteristics of the additives.

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A Numerical Analysis of the Elastohydrodynamic Lubrication of Connecting Rod Bearings (커넥팅 로드 베어링의 EHL에 관한 수치해석)

  • 김병직;김경웅
    • Tribology and Lubricants
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    • v.12 no.3
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    • pp.63-71
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    • 1996
  • The connecting rod bearing, which is subjected to periodical dynamic loading, is an impoRant component of the reciprocating engine. In the operation of this bearing, significant parameters are the oil film thickness and the film pressure. Peak film pressures of 20-30 MPa are not uncommon. So the elastic deformation of the bearing housing can have a significant effect on the bearing performance. In this study, a numerical analysis of connecting rod bearing is investigated. Elastic deformation of the bearing housing is considered in the analysis. Separate hydrodynamic and structural analysis are coupled through a direct iterative process. It is shown that as the result of the elastic deformation of the bearing housing, the eccentricity ratio is increased, and the minimum value of the minimum film thickness and the maximum value of the maximum film pressure are decreased. The variations of rotational speed and cylinder pressure affect the minimum film thickness and the maximum film pressure variations of the connecting rod bearing.

The Analysis of Oil Spill Spreading Using SAR Images (SAR영상을 이용한 유류 오염 분포 분석)

  • Kim Taerim;Lee Soo Hyung
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.2 no.2
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    • pp.38-48
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    • 1999
  • The oil spill accident near Goeje Island on April 3, 1997 was analyzed using two RADARSAT SAR images. The first scene was acquired 3 days after the accident as an extended low beam mode and the second scene was acquired 12 hours after the first scene as a standard beam mode. The two scenes showed slicks not only by oil spills but also by oil spill look-alikes caused by wind sheltering, low wind, natural film, and etc. These slicks were analyzed and classified, and natural films produced from aquaculture farms around Goeje Island were also suggested as a strong candidate for slicks on SAR images. The study with two SAR imags indicated the oil spill patterns which spreaded to the southwest immediately after the accident and switched the direction to the east. The spreading patterns shown in two SAR images also showed good agreement with in-situ observations.

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Analysis for Lubrication of the Piston Ring Considering Oil Transport-Examples (오일이송을 고려한 피스톤 링의 윤활 해석-예제)

  • 이재선;한동철
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1998.10a
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    • pp.358-364
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    • 1998
  • Lubricational characteristics at the interface between the piston ring and the cylinder liner are considered in this paper. To verify that surface shape and operating conditions of the engine can affect the state of lubrication, the changes of the minimum film thickness and friction force are calculated with various conditions. Oil starvation and open-end boundary condition are used to determine computational boundaries as reported on previous paper for lubrication analysis for the piston ring. From this analysis, it can be found that lubricational characteristics are seriously affected by degree of oil starvation, surface shape and operating conditions.

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Analysis of Ring Pack Lubrication

  • Lee, Jae-Seon;Han, Dong-Chul
    • Journal of Mechanical Science and Technology
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    • v.14 no.9
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    • pp.928-934
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    • 2000
  • This paper describes a method developed for the simulation of ring pack lubrication characteristic in an internal combustion engine. In general, the quantity of oil supply for piston ring lubrication may be insufficient in filling the entire volume formed at the interference between the piston ring and the cylinder liner. Thus the oil starvation condition should be considered in analyzing piston ring lubrication. In order to reasonably estimate the amount of oil left over on the cylinder liner, the flow rate at the posterior portion of the interface should be calculated with an adequate boundary condition that confirms flow continuity condition. In this analysis, oil starvation and open-end boundary conditions are considered at the inlet and outlet of the piston rings. The lubrication characteristic of each piston ring is obtained by an iterative method with sequential steps. It is revealed that piston rings are operated under oil starvation in most operating cycles and the result under these conditions are quite different from that with the fully-flooded assumption.

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