• Tribology and Lubricants
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• 제20권4호
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• pp.190-196
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• 2004

The effect of tangential loading on the subsurface stress field has been investigated numerically. As tangential load increases, the subsurface stress field expands more widely to the direction of the tangential load. Places of the maximum shear stress and the maximum effective stress are getting closer to the surface with the increasing tangential load. The tangential load in an elasto-hydrodynamic lubrication condition is so low that it does not affect the subsurface stress field.

• Tribology and Lubricants
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• 제9권1호
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• pp.45-54
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• 1993

The lubrication characteristics of line contacts between the vane and cam ring in an oil hydraulic vane pump with intravanes have been investigated. Variations of the radial acting force of a vane were calculated from previously measured results of dynamic internal pressures in four chambers surrounding a vane, and variations of the film thickness were estimated in both the rotational speed range from 500 to 1500 rpm and in the delivery pressure range from 1 to 14 MPa. The results indicate the variations of the radial acting force and film thickness. It is found that the regimes of lubrication in the vane tip contacts lover rigid-isoviscous to rigidvariable viscosities.

• Tribology and Lubricants
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• 제20권1호
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• pp.27-32
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• 2004

This paper presents unsteady oil flow behaviors in the engine lubrication network to clarify the differences between continuous and discontinuous oil supply crankshaft system. Using commercial network analysis program, Flowmaster2, engine lubrication network system analysis were carried out. And effects of crankshaft speed and supplied oil pressure on pressure fluctuation in oil groove and oil flow rate to each bearing were analyzed.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제28회 추계학술대회
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• pp.30-37
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• 1998

It is well known that reduction of friction loss due to the valve train system greatly affects on improvement of fuel economy in internal combustion engine. In order to investigate friction characteristics of valve train system we carried out friction force measurement using test rig developed by ourselves. From test results, we concluded that characteristics of lubrication and friction torque on the valve train system such as mixed and hydrodynamic was mainly governed the contact type between cam and tappet.

• Tribology and Lubricants
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• 제20권1호
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• pp.14-20
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• 2004

In high-speed gas-levitation applications a high compressibility number may bring a numerical difficulty in predicting generated pressure profiles accurately as it causes erroneous sudden pressure overshoot and oscillation in the trailing-edge. To treat the problem, in this study an exact exponential high-order shape function is introduced in the FE lubrication analyses. It is shown by various example applications that the high-order shape function scheme can successfully subdue undesired pressure overshoot and oscillation.

• Tribology and Lubricants
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• 제17권6호
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• pp.447-452
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• 2001

In development process of engine lubrication system, many failure cases are related with aeration problem. Therefore, it is very important to clarify the aeration in the engine oil circuit system. As of today, many factors have been introduced as the major cause in the engine oil aeration. However, still many test data related with those are required to clearly understand it. In this paper the aeration measurement system and calculation method are introduced. And also using this system we measured engine oil aeration for various cases. From these results some conclusions are reduced.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제32회 추계학술대회 정기총회
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• pp.107-114
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• 2000

As one of the strategies to sustain the maximum output with the total minimum cost, huge plants worldwide, such as steel mills, refineries, petrochemical plants, and etc., may and will plan and implement the minimization of operating and maintenance costs for their own. This paper is to review the foreign cases of energy savings through lubrication improvements as one of the actions for that purpose and summarize their directions, and also to look at one such local test case.

• Tribology and Lubricants
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• 제13권2호
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• pp.46-51
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• 1997

Crosshead bearings in two-stroke marine diesel engines are operated under severe conditions of lubrication because the load on the bearing is unidirectional and the sliding speed is very low and oscillatory. In this paper, the motion of journal in a bearing is investigated using the lubrication theory. Several locus paths are presented to show the effects of oil groove size, bearing clearance and oil inlet pressure. It is found that the minimum film thickness is affected by the oil groove and bearing clearance, and the oil groove is an important design factor.

• Journal of Advanced Marine Engineering and Technology
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• 제26권2호
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• pp.200-208
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• 2002

The flash temperature of the cam-roller contacting surface for a marine diesel engine was analysed numerically. The elastohydrodynamic lubrication pressure and film thickness were adopted to get more accurate frictional coefficient, heat flux and temperature distribution. The maximum flash temperature was increased with both the increasing slip ratio of the contacting surfaces and increasing external load. This study tells that the temperature analysis is an indispensable procedure in designing elastohydrodynamic lubrication contacts on which the slip occurs.

• Tribology and Lubricants
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• 제23권6호
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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.