• 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.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.99-100
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• 2002

Radial, tilting-pad proceeding bearings are applied in high speed rotating machines operating at stable small and mean loads and the peripheral speeds of proceeding reaching 150 m/s. The operation of bearing can be determined by static characteristics including the oil film pressure, temperature and viscosity distributions, minimum oil film thickness, load capacity, power loss, oil flow. The operation of 5-lobe tilted-pad proceeding bearing has been introduced at the assumption of adiabatic oil film. The oil film pressure, temperature and viscosity distributions habe received by iterative solution of the Reynolds', energy and viscosity equations. The resulting oil film force, minimum oil film thickness, power loss. oil flow, maximum oil film pressure, maximum temperature were computed for different sets of bearing geometric parameters as: bearing length to diameter ratio, pad angular length and width as well as pad relative clearance.

• Tribology and Lubricants
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• v.23 no.6
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• pp.255-260
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• 2007

This paper presents the contact pressure distribution of pin bushing bearings for various lubrication friction modes such as oil film and elastohydrodynamic lubrication contacts, a mixed lubrication contact, a boundary contact, and a dry contact. During a sliding contact of a plain bearing, the boundary and dry rubbing contacts are dominated between a piston pin and a pin bushing bearing. This may come from a micro-scale clearance, an explosive impact pressures from the piston head, and an oscillatory motion of a pin bearing. The computed results show that as the oil film parameter $h/{\sigma}$ is increased from the dry rubbing contact to the oil film lubrication friction, the maximum oil film pressure is radically increased due to an increased viscous friction with a thin oil film thickness and the maximum asperity contact pressure is reduced due to a decreased asperity contact of the rubbing surfaces.

• Tribology and Lubricants
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• v.25 no.1
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• pp.1-6
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• 2009

In this paper, the minimum oil film thickness and the maximum oil film pressure of engine bearings have been analyzed by using the elastohydrodynamic theory and Taguchi's design method as functions of the oil groove width, oil hole diameter, oil hole position, and oil supply pressure. The optimized design of the engine bearing f3r an automotive Diesel engine is very important for supporting a load-carrying capacity due to gas pres-sures from the engine combustion chamber and inertia forces of the piston. The optimized design data of engine bearings indicated that the optimized oil groove width and an oil diameter of a engine bearing are 8mm at the speed of 2,000 rpm for a given 4-cylinder Diesel engine. Thus, the oil groove oil groove and an oil hole for high performances of an engine bearing may be considered as major design parameters compared to other design factors, which are strongly related to the minimum oil film thickness and the maximum oil pressure distribution of the engine oil.

• 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.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.113-114
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• 2002

Radial, tilting 12-pad proceeding bearings are applied as the radial bearings of vertical rotors of water turbines. The mean loads are stable at the peripheral speeds of proceeding reaching 50 m/s. The operation of tilting 12-pads proceeding bearing has been introduced at the assumption of adiabatic oil film. The oil film pressure, temperature and viscosity distributions have been obtained by iterative solution of the Reynolds', energy and viscosity equations. The resulting oil film force, minimum oil film thickness, power loss, oil flow, maximum oil film pressure, maximum temperature have been computed for different load angle of bearing.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.6
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• pp.666-674
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• 2007

It is very important to estimate static squeezing pressure distributions for lining material of sterntube after bearing at dry dock stage since the maximum squeezing pressure value can be one of the significant characteristics representing coming navigation performances of the propulsion system. Moderate oil film pressure between lining material and propulsion shaft is also essential for safe ship service. In this paper, Hertz contact theory is explained to derive static squeezing pressure. Reynolds equation simplified from Navier-Stokes equation is centrally differentiated to numerically obtain dynamic oil film pressures. New shaft alignment technology of nonlinear elastic multi-support bearing elements is also used in order to obtain external forces acting on lining material of bearing. For 300K DWT class VLCC with synthetic bush of sterntube after bearing, static squeezing pressures are calculated using derived external forces and Hertz contact theory. Optimum partial slope of the after bush is presented by parametric shaft alignment analyses. Dynamic oil film pressures are comparatively evaluated for partially bored and unbored after bush. Finally it is proved that the partial slope can drastically reduce oil film pressure during engine running.

• Tribology and Lubricants
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• v.25 no.3
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• pp.157-162
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• 2009

In this paper, the hydrodynamic pressure and minimum oil film thickness of a pin bush bearing for a connecting rod have been analyzed as functions of the number of oil grooves and an arc length of oil grooves. The lubrication characteristic of a pin bush is governed by oil groove design factors, which are considered in this study. The most influential design parameter is a number of oil grooves, which is three oil grooves with an arc length of oil groove, 1/6($60^{\circ}$). This means that oil groove with a long arc length of a pin bush does not contribute to the hydrodynamic pressure development. Thus the optimal design of a pin bush is necessary with an increased number of oil grooves and a reduced arc length.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.275-282
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• 2004

The engine bearing transmits the powers from cylinder to crankshaft with small clearance between con-rod and crankpin. The minimum oil film thickness is a significant parameter in the operation of bearing. The contact pressure of bearing should be considered for the reason that elastic deformation of bearing be caused by contact pressure of bearing. There are important factors which are maintaining of minimum oil film thickness expecting of the length of maximum and minimum oil film thickness with changing of the loads to keep running normally. Furthermore, this study is very crucial to develop the design of engine bearing and crankshaft system.

• 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.