• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 2000년도 제31회 춘계학술대회
• /
• pp.114-120
• /
• 2000

EHL analysis of connecting rod bearing is proposed which includes effects of temperature variation in lubrication film. Lubrication film temperature is treated as a time-dependent, two-dimensional variable which is averaged over the film thickness, while connecting rod big end temperature is assumed to be time-independent and three-dimensional. It is assumed that a portion of the heat generated by viscous dissipation in the lubrication Him is absorbed by the film itself, and the remainder flows into the bearing surface. Mass-conserving cavitation algorithm is applied and the effect of variable viscosity is included to solve the Reynolds equation. Simulation results of the connecting rod bearing of internal combustion engine are presented. It is shown that the temperature variation has remarkable effects on the bearing performance. It is concluded that the EHL analysis considering effects of the temperature variation is strongly recommended to predict the bearing performance of connecting rod big end On internal combustion engine.

• Tribology and Lubricants
• /
• 제17권3호
• /
• pp.228-235
• /
• 2001

EHL analysis of connecting rod bearing is proposed which includes effects of temperature variation in lubrication film. Lubrication film temperature is treated as a time-dependent, two-dimensional variable which is averaged over the film thickness, while connecting rod big end temperature is assumed to be time-independent and three-dimensional. It is assumed that a portion of the heat generated by viscous dissipation in the lubrication film is absorbed by the film itself, and the remainder flows into the bearing surface. Mass-conserving cavitation algorithm is applied and the effect of variable viscosity is included to solve the Reynolds equation. Simulation results of the connecting rod bearing in internal combustion engine are presented. It is shown that the temperature variation has remarkable effects on the bearing performance. It is concluded that the EHL analysis considering effects of the temperature variation is strongly recommended to predict the connecting rod bearing performance in internal combustion engine.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 1998년도 제27회 춘계학술대회
• /
• pp.228-234
• /
• 1998

The aim of this paper is to study the characteristics of thermo-hydrodynamic lubrication in the bimetal bearings. Bimetal bearing is composed of lining and back metal. The THD model is proposed to calculate oil film temperature and pressure in the bimetal bearing. As results of analysis, comparative results of maximum bearing temperature are presented for the various materials and thickness of lining metal.

• 한국생산제조학회지
• /
• 제20권1호
• /
• pp.96-100
• /
• 2011

The hydrostatic bearings have a relatively small run-out comparing to its shape error by fluid film effect in hydrostatic state as like pneumatic bearing and have a high stiffness, load capacity and damping characteristics. As there is no maintenance and semipermanent in these bearing type, it has been usually adopted as main spindle bearing for grinding machine. In this thesis, to develop hydrostatic bearing for high speed spindle, the cooler setting temperature, bearing clearance and nozzle pressure of belt-driven hydrostatic bearing are investigated. The bearing temperature is decreased, as the cooler setting temperature is lower, nozzle pressure is higher and bearing clearance is wider. The front temperature of bearing is nearly $8^{\circ}C$ higher than the rear one up to 13,000 rpm of spindle revolution. The thermal deflection of X-axis is ${\pm}16\;{\mu}m$ in range of 12,000 rpm-13,000 rpm. Therefore, it is conformed that the built-in motor hydrostatic bearing can be used to high speed spindle.

• Tribology and Lubricants
• /
• 제23권1호
• /
• pp.1-8
• /
• 2007

Turbocharger bearings are under the circumstance of high temperature, moreover rotated at high speed. It is necessary to be designed to overcome the high temperature. So the type of oil inlet port, the inlet oil temperature and the sort of engine oil should be designed, controlled and selected carefully in order to reduce the bearing inside temperature. Therefore, in this study, the effects of the type of inlet oil port, inlet temperature and the sort of engine oil on the performance of a turbocharger bearing are to be investigated. It is found that the type of oil inlet ports, the control of inlet oil temperature and the selection of engine oil type play important roles in determining the temperature and pressure, then the friction and load of a turbocharger journal bearing at high speed operation.

• Tribology and Lubricants
• /
• 제13권1호
• /
• pp.76-81
• /
• 1997

The lubrication characteristics of high-speed roller bearings at oil-starvation have been investigated empirically using the bearings employed in small industrial gas turbine engines. Testing was done by simulating the oil-starvation conditions in engines, such as stopping the oil-supply to the bearing during normal operating, starting without oil-supply at atmospheric temperature, and accelerating with oil-supply at atmospheric temperature. During testing, the temperature of bearing, the power consumption, and the rotating resistance of the bearing were measured. From this study, on the contrary to the ball bearing, it was found that the resistance of the bearing was higher at the regime of without oil-supply than that at the regime of with oil-supply, despite less power consumption.

• KSTLE International Journal
• /
• 제7권2호
• /
• pp.35-44
• /
• 2006

Turbocharger bearings are under the circumstance of high temperature, moreover rotated at high speed. It is necessary to be designed overcoming the high temperature. So the type of oil inlet port, the inlet oil temperature and the sort of engine oil should be designed, controlled and selected carefully in order to reduce the bearing inside temperature. In this study, the influence of aerated oil on a high-speed journal bearing is also examined by using the classical thermohydrodynamic lubrication theory coupled with analytical models for viscosity and density of air-oil mixture in fluid-film bearing. Convection to the walls and mixing with supply oil and re-circulating oil are considered. The considered parameters for the study of bubbly lubrication are oil inlet port's type, oil aeration level and shaft speed. It is found that the type of oil inlet ports and shaft speed play important roles in determining the temperature and pressure, then the friction and load of journal bearing at high speed operation. Also, the results show that, under extremely high shaft speed, the high shear effects on aerated oil and the high temperature effects are canceled out each other. So, the bearing load and friction show almost no difference between the aerated oil and pure oil.

• Tribology and Lubricants
• /
• 제23권5호
• /
• pp.207-218
• /
• 2007

Turbocharger bearings are under the circumstance of high temperature, moreover rotated at high speed. It is necessary to be designed overcoming the high temperature. So the type of oil inlet port, the inlet oil temperature and the sort of engine oil should be designed, controlled and selected carefully in order to reduce the bearing inside temperature. In this study, the influence of aerated oil on a high-speed journal bearing is also examined by using the classical thermohydrodynamic lubrication theory coupled with analytical models for viscosity and density of air-oil mixture in fluid-film bearing. Convection to the walls and mixing with supply oil and re-circulating oil are considered. The considered parameters for the study of bubbly lubrication are oil inlet port's type, oil aeration level and shaft speed. It is found that the type of oil inlet ports and shaft speed play important roles in determining the temperature and pressure distribution, then the friction in a journal bearing at high speed operation. Also, the results show that, under extremely high shaft speed, the high shear effects on aerated oil and the high temperature effects are canceled out each other. So, the bearing load and friction show almost no difference between the aerated oil and pure oil.

• Tribology and Lubricants
• /
• 제34권4호
• /
• pp.138-145
• /
• 2018

Elliptical bearings are widely used for large steam turbines owing to their excellent load carrying capacity and good dynamic stability. Power loss in bearings is an extremely important parameter, especially for high turbine capacities. Optimization of operation conditions and design variables such as bearing clearance and bearing length can reduce the power loss in elliptical bearings. Although changes in the oil supply method have served to increase the efficiency of the tilting pad journal bearing, it has not explicitly improved elliptical bearings. In this study, we verify the static characteristics of an elliptical bearing by changing the direction of oil supply. We evaluate the bearing power loss and bearing metal temperature, and compare the bearing performance and reliability in different test cases. The direction of oil supply is $90^{\circ}$ (9 o'clock) and $270^{\circ}$ (3 o'clock) when the rotor rotates in a counterclockwise direction. We use an elliptical bearing with an inner diameter and active length of 220.30 and 110.00 mm, respectively. Bearing power loss and bearing metal temperatures are measured and evaluated by rotor rotational speed, oil flow rate, and bearing load. The results reveal a 20 reduction in the power loss when the direction of oil supply is 90. Furthermore, the oil film on the upper part of the bearing has a high temperature when the direction of oil supply is $90^{\circ}$. In contrast, when the direction of oil supply is $270^{\circ}$, the oil film on the upper part of the bearing is relatively cold.

• Tribology and Lubricants
• /
• 제9권2호
• /
• pp.29-35
• /
• 1993

The thermohydrodynamic(THD) performance of a large tilting pad journal bearing in laminar and turbulent flow regions is investigated experimentally. The continuous shaft surface temperature, and bearing surface temperature are measured along with the shaft speed and the bearing load for various flow rates. It is observed that the shaft surface temperature is constant in the circumferential direction and increases with the increase of shaft speed in both low and high shaft speed region, however, there exist transition region where the shaft surface temperature decreases with the increase of shaft speed. When the turbulence occurs in the lubricant film, both the inlet and maximum bearing surface temperature steeply increase and the temperature gradient in the circumferential direction decreases.