• Title/Summary/Keyword: Oil film analysis

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Numerical Analysis on the Oil Film Behavior of Engine Main Bearing Considering Dilution of Diesel Fuel (경유 혼입을 고려한 엔진 메인 베어링의 유막거동에 관한 수치적 연구)

  • Kim, Han-Goo
    • Tribology and Lubricants
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    • v.26 no.4
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    • pp.240-245
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    • 2010
  • This paper describes the influence on engine main bearing behavior of the oil film when the fuel is diluted on a diesel engine equipped with DPF system. Oil film pressure and the thickness is calculated in accordance to the fuel dilution. The calculation is based on the numerical analysis of the engine main bearing. As a result, the engine oil viscosity decreased as the fuel dilution increased. This led the increment of the maximum oil thickness pressure. Verification of the minimum oil film thickness settlement by the engine gas pressure and the fuel dilution was confirmed. Destruction possibility of the engine main bearing was foreseen when the engine speed was 2000 rpm with the fuel dilution 15% and the 5W40 engine oil.

Analysis on the Friction Characteristics of Low Viscosity Engine Oils (저점도 엔진오일이 마찰특성에 미치는 영향에 관한 해석적 연구)

  • Kim, Chung-Kyun
    • Tribology and Lubricants
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    • v.21 no.6
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    • pp.249-255
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    • 2005
  • In this paper, the friction characteristic of engine bearings has been analyzed in terms of a friction loss power, a minimum film thickness and an oil film pressure. This analysis has been focused on the fuel economy improvement with a low viscosity engine oil such as SAE 0W-40, which is used for a friction loss reduction and increased for a Diesel fuel economy. The friction loss power, the minimum oil film thickness and oil film pressure distribution for plain bearings of a Diesel engine are analyzed using an AVL's EXCITE program with a conventional engine oils of SAE 5W-40 and 10W-40, and a low viscosity engine oil of SAE 0W-40. The computed results indicate that a viscosity of engine oils is closely related to the friction loss power and the decreased minimum film thickness in which is a key parameter of a load carrying capacity of an oil film pressure distribution. When the low viscosity engine oil is supplied to engine bearings, it does not affect to the formation of a minimum oil film thickness. But the friction loss power has been significantly affected by low viscosity engine oil at a low operating temperature of 0. Based on the FEM computed results, the low viscosity engine oil at a low temperature range will be an important factor for an improvement of the fuel economy improvement.

A Study on the Circumferential Groove Effects on the Minimum Oil Film Thickness in Engine Bearings

  • Cho, Myung-Rae;Shin, Hung-Ju;Han, Dong-Chul
    • Journal of Mechanical Science and Technology
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    • v.14 no.7
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    • pp.737-743
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    • 2000
  • This paper presents the effects of circumferential groove on the minimum oil film thickness in engine bearings. The fluid film pressures are calculated by using the infinitely short bearing theory for the convenience of analysis. Journal locus analysis is performed by using the mobility method. A comparison of minimum oil film thickness of grooved and ungrooved bearing is presented. It is found that circumferential $360^{\circ}$ groove only reduces the absolute magnitude of the oil film thickness, but $180^{\circ}$ half groove affects the shape of film thickness curve and position of minimum oil film thickness.

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EHD Analysis on Lubrication Mechanics of Connecting Rod Bearing

  • Kim, Chung-Kyun;Kim, Sung-Won;Kim, Han-Goo
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2002.10b
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    • pp.405-406
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    • 2002
  • The main subject of this paper is analyzing the patterns of maximum oil film pressure and the minimum oil film thickness under various pre-conditions of geometric shape as functions of bearing groove and proceeding oil hole in the connecting rod bearing. As the major analytical tool, elastohydrodynamic lubrication analysis has been applied and two-intertwined results of maximum oil film pressure and minimum oil film thickness have been compared and analyzed using EXCITE program. From computed results, the optimal lubrication conditions as geometric shape of bearing groove and the proceeding oil hole have been investigated. This may be useful for the bearing designer as a firm reference.

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The Effect of Oil Rheology on Film Thickness in Engine Journal Bearing (윤활유의 유동특성이 기관 저어널 베어링의 유막두께에 미치는 영향)

  • 이동호;장병주
    • Transactions of the Korean Society of Automotive Engineers
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    • v.2 no.4
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    • pp.9-17
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    • 1994
  • Effect of Newtonian and non-Newtonian oils on minimum ol film thickness in engine journal bearing were investigated at various oil viscosities. The influence of oil viscosity and engine operating conditions on minimum oil film thickness of main bearing and con-rod bearing was examined. Minimum oil film thickness for Newtonian oils increased uniformly with kinematic viscosity. But the correlation between kinematic viscosity and minimum oil film thickness was very poor for non-Newtonian oils. According to the straight-line regression analysis for non-Newtonian oils, high temperature high shear viscosity at 1 $1{\times}10^6Sec^{-1}$, $150^{\circ}C$ increase the coefficient of determination from 0.41 to 0.77. Con-rod bearing showed better correlation between minimum oil film thickness and engine operating conditions than main bearing.

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Pin-Boss Stress Analysis Coupled with Oil Film Pressure of a Diesel Engine Piston Receiving 200 bar Combustion Pressure (200 bar 연소압을 받는 디젤엔진 피스톤 핀-보스의 유막 압력을 고려한 응력해석)

  • Chun, Sang-Myung;Lee, J.S.;Joo, D.H.;Park, S.J.
    • Tribology and Lubricants
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    • v.24 no.4
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    • pp.196-204
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    • 2008
  • In this study, the pressure distributions on the oil film of piston pin bearings are found by two-dimensional lubrication analysis in order to help the optimum design of the bearings of piston pin. The lubrication analysis is carried out together with an equation related with the oil pressure-viscosity index. The oil film pressure distribution is used as an input data for pressure boundary conditions at the piston pin-boss surface. Finally, the piston pin-boss stress distribution coupled with the thermal stress is calculated, and then compared with the results of the stress analysis which is not counted with the oil film pressure boundary condition.

Numerical Analysis on the Oil Film Behaviors of Connecting Rod Bearings Based on the Elastohydrodynamic Lubrication (탄성유체윤활에서 작동하는 커넥팅 로드 베어링의 윤활막 거동에 관한 수치적 연구)

  • 김청균;김한구
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.4
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    • pp.36-41
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    • 2004
  • The purpose of this paper is analyzing the oil film pressure distribution and the minimum oil film thickness for a connecting rod bearing using an A VL's EXCITE program. It is very important to understand optimized oil supplying holes and oil groove dimensions for supporting sufficiently inertia forces and gas pressures from the combustion chamber for a Diesel engine. The computed results indicate that the optimized oil groove width of a bearing and oil hole of a journal are recommended for high performance of a connecting rod bearing at the elastohydrodynamic lubrication zone. These results as design parameters are very useful data for a bearing designer as a firm reference of an automotive engine.

Numerical Analysis on the Oil Film Behaviors of Connecting Rod Bearings Based on the Elastohydrodynamic Lubrication (탄성유체윤활에서 작동하는 커넥팅 로드 베어링의 윤활막 거동에 관한 수치적 연구)

  • 김청균;김한구
    • Transactions of the Korean Society of Automotive Engineers
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    • v.12 no.4
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    • pp.34-34
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    • 2004
  • The purpose of this paper is analyzing the oil film pressure distribution and the minimum oil film thickness for a connecting rod bearing using an A VL′s EXCITE program. It is very important to understand optimized oil supplying holes and oil groove dimensions for supporting sufficiently inertia forces and gas pressures from the combustion chamber for a Diesel engine. The computed results indicate that the optimized oil groove width of a bearing and oil hole of a journal are recommended for high performance of a connecting rod bearing at the elastohydrodynamic lubrication zone. These results as design parameters are very useful data for a bearing designer as a firm reference of an automotive engine.

Effect of Outdoor Temperature on the Refrigerant Behavior in the Compressor of a Heat Pump Operating at Heating Mode (열펌프의 난방운전시 외기온이 압측기의 냉매거동에 미치는 영향)

  • 이재효;김병균;이건우
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.16 no.5
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    • pp.452-458
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    • 2004
  • The major cause of compressor failure is the decrease of oil viscosity due to floodback. In most previous researches on the compressor reliability, the relationship between oil circulation rate and performance or oil viscosity has been studied. Another research topic is flow visualization by using a sight glass on the bottom of a compressor sump area and accumulator. Both oil film thickness and oil level through the sight glass should be assessed for compressor reliability if the oil content of the mixture is small and low viscosity raise poor lubrication of pump bearing. In this study, the compressor reliability was assessed by measuring the viscosity of the mixture and calculating oil film thickness. The analysis of the relationship between bottom shell super heat and oil film thickness at heating operation was peformed. It is concluded that bottom shell superheat does not perfectly stand for the mixture's behavior for a low ambient heating operation and oil film thickness can give more detailed and direct criteria for compressor reliability.

Finite Element Analysis of Contact Pressure Behavior in Compression Ring-Oil Film (압축링-유막간의 접촉압력 거동에 관한 유한요소해석)

  • 김청균;김한구;한동철
    • Tribology and Lubricants
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    • v.11 no.4
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    • pp.53-57
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    • 1995
  • The contact pressure behavior is examined by means of a finite element analysis. The oil film between the piston ring and cylinder liner is analyzed on the basis that it behaves like a polymer material. The calculated results indicate that a shape of sloping edge with a straight line, which is designated as a Model III, shows a good performance on the contact pressure behavior for the increased speed. Obviously, the ring face profiles play an important role on the contact pressure between compression ring and oil film.