• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1993년도 춘계학술대회 및 공장견학
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• pp.39-53
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• 1993

The minimum oil film thickness(MOFT) in the connecting-rod bering of a 1.5 liter, L-4, gasoline engine is measured up to 5500 rpm and calculated to study the dynamically loaded engine bearing. Short bearing approximation and Mobility method are used for theoretical analysis of oil film charactrtistics. And cylinder pressure, crank-pin surface temperature and bearing tenp ture are measured as the input data of theoretical analysis. The MOFT are measured by the total capacitance method(TCM). To improve the reliability of the test results, a reasonable detmuuination method of bearing clearance is introduced and used, and the effects of cavitation and aeration on the test results are neglected. The crankshaft is grounded by means of a slip ring. A scissor type linkage system was developed to measure the MOFT and bearing temperature. The effects of engine speed, load and oil viscosity on the measured and calculated minimum oil film thicknesses are investigated at 1500 to 5500 rpm. From the comparison between the measured and calculated MOFT, it is found that a qualitative similarity exists between them, but in all cases, the measured MOFT are smaller than those calculated.

• Tribology and Lubricants
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• 제2권2호
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• pp.32-43
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• 1986

The mobility method is used for optimizing dynamically-loaded journal bearings. Connecting -rod bearings in both diesel and gasoline engines are optimized by parametric studies of bearing span and clearance. The inertia effect of the connecting-rod is also included in this study. Minimum film thickness, maximum film pressure, and friction loss are calculated to satisfy the design conditions in both engines.

• Tribology and Lubricants
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• 제25권3호
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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.

• Tribology and Lubricants
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• 제20권3호
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• pp.119-124
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• 2004

Engine bearing system is generally affected by aeration. In this paper, the aeration effects on the engine crankshaft bearing system were studied. To do this, unsteady oil flow analysis on the engine crankshaft oil circuit system was carried out. And aeration effects on the bearing system were simulated to figure out lubrication characteristics of the each bearing such as oil flow rate, minimum oil film thickness, friction loss and increase of oil temperature.

• 오토저널
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• 제14권2호
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• pp.110-119
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• 1992

Crank pin temperatures were measured and analyzed to find out practical method which can predict the engine bearing reliability. The measuring points were determined to be near the MOFT region and far from that by theoretical calculation. The effect of engine running condition, oil temperature, the change of oil circuit into bearing and crankshaft endplay on crank pin temperature were experimentally tested. The result obtained was as following. The crank pin temperature was dependent on oil film thickness and directly influenced by the change of test condition. Also, the length of the crankshaft endplay was confirmed to be critical to connecting rod bearing failure. In conclusion, we found that the measurement method of crank pin temperature can be used for predicting the engine bearing reliability.

• Tribology and Lubricants
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• 제22권1호
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• pp.47-52
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• 2006

It is very important to control pressure and flow rate distribution on each component of engine lubrication network. Sometimes many kinds of orifice are used to control flow rate in the hydraulic lubrication field. In this study orifices were adopted on the lubrication network to control oil flow rate distribution. And unsteady transient flow network analysis was carried out to find out the effects of orifices on the engine oil circuit system.

• Tribology and Lubricants
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• 제20권2호
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• pp.84-90
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• 2004

It is very important to improve the durability and reliability of crankshaft because of conflicting demands for lower fuel consumption and higher power output. In this study, for the crankshaft bearing design, analyses were conducted to determine the lubrication characteristics such as oil flow rate, minimum oil film thickness, friction force and increase of oil temperature at main bearing and connecting rod bearing. Additionally, supplied oil pressure and temperature effects on the bearings were simulated to figure out lubrication characteristics on the bearings. Finally the effects of increasing the bearing width and clearance were introduced on the lubrication characteristics.

• Tribology and Lubricants
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• 제22권1호
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• pp.14-19
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• 2006

VCT(Variable Cam Timing) system is one of very useful engine components to improve fuel economy and overcome emission regulation etc. In order to adapt the VCT to a base engine, many design mod ifications in the mechanical and lubrication fields are required. Especially, because the VCT performance itself depends on supplied oil flow rate and pressure, it is very important to evaluate the engine lubrication system in a viewpoint of supplied oil flow rate and pressure. In this paper, unsteady transient flow network analysis on the engine oil circuit system was carried out to do this.

• Tribology and Lubricants
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• 제17권6호
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• pp.426-434
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• 2001

The hermetic reciprocating compressor driven by the BLDC motor rotating with variable speeds, is modelled and analyzed for dynamic characteristics. The governing equations of piston, connecting rod and crank-shaft of the reciprocating compression mechanism and characteristics of driving torque of the motor are obtained. Dynamic behavior of the crankshaft supported on 2 journal bearings is analyzed considering compression load and eccentric unbalance for the 4 rotating speeds of crankshaft. And. reaction forces generated from oil film in the journal bearings are analyzed under transient condition using Reynolds' equation. To take into account the dynamic characteristics depending on the variable rotating speeds, comparison on the dynamic behavior of crank-shaft is made for the 4 operating modes of the compressor. Results show that the magnitude of crankshaft locioperating on the lower rotating speeds is more larger than the higher ones due to reduction of inertia force of the reciprocating piston.

• Journal of Mechanical Science and Technology
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• 제17권6호
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• pp.844-853
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• 2003

In this paper, a dynamic analysis of the reciprocating compression mechanism of a small refrigeration compressor is performed. In the problem formulation of the mechanism dynamics, the viscous frictional force between the piston and the cylinder wall is considered in order to determine the coupled dynamic behaviors of the piston and the crankshaft. Simultaneous solutions are obtained for the equations of motion of the reciprocating mechanism and the time-dependent Reynolds equations for the lubricating film between the piston and the cylinder wall and for the oil films on the journal bearings. The hydrodynamic forces of the journal bearings are calculated by using a finite bearing model along with the Gumbel boundary condition. A Newton-Raphson procedure is employed in solving the nonlinear equations for the piston and crankshaft. The developed computer program can be used to calculate the complete trajectories of the piston and the crankshaft as functions of the crank angle under compressor-running conditions. The results explored the effects of the radial clearance of the piston, oil viscosity, and mass and mass moment of inertia of the piston and connecting rod on the stability of the compression mechanism.