Floating Ring Journal Bearings Research Articles

An optimization-based identification study of cylindrical floating ring journal bearing system in automotive turbochargers

An optimization-based identification study of cylindrical floating ring journal bearing system in automotive turbochargers

Floating ring journal bearings of multilobe design in turbochargers

The floating ring bearings system of turbocharger operates at high rotational speeds and high temperatures on the inlet of exhaust gases. Usually, such system applies the cylindrical profile of floating ring and stationary sleeve. The changes of the geometry of inner sliding surface of stationary sleeve as well as external or inner sliding surface of floating ring into multilobe surfaces allow for obtaining additional operation properties. It can be expected the changes in the static and dynamic characteristics of bearing what results in higher speeds of operation and better stability. The paper considers application of multilobe sliding surfaces in the design of turbocharger as well as the computation possibilities of such design bearings. Exemplary results of the computation of static and dynamic characteristics for the chosen types of multilobe bearings support their application in high speed rotating machinery including the floating ring bearings of turbochargers. Applied code and the results of this work allow calculating the stability of rotors operating in the bearings with the turbulent model of oil film and particularly the high speed floating ring bearings.

A steady-state performance analysis of a non-circular cylindrical floating ring journal bearing

This paper analyses the steady-state performance behaviour of a new type of journal bearing, i.e. the non-circular cylindrical floating ring journal bearing. It consists of a floating ring in between the shaft and the upper and lower lobes of a two-lobe bearing. The journal and the inner surface of the ring are cylindrical while bearing surfaces are non-circular. The classical Navier–Stokes equations in the modified form together with the continuity equation are being solved by the finite element method. The cylindrical coordinates form of the Navier–Stokes equation and continuity equation are used in the present analysis to compute the important proposed bearing characteristics. In this analytical study, the finite bearing approximation ( L/ D=1) with a C2/ C1 value of 0.70 and 1.30 are being used to simulate the behaviour of non-circular cylindrical floating ring journal bearing. The Reynold’s boundary condition is used to enumerate the performance of the proposed bearing. In the present analysis, the steady-state parameters in terms of an inner and outer film eccentricity ratio, a speed ratio, attitude angle, load capacity, friction coefficient parameter, axial oil flow and rise in temperature variable are determined. The results reveal that the steady-state performance of the non-circular floating ring journal bearing is superior to a plain cylindrical floating ring journal bearing.

Turbocharger vibration shows nonlinear jump

Automotive turbochargers are known to operate into the self-excited unstable region. In the past these instabilities have been accepted as unavoidable, but recent developments in analysis and instrumentation may make it possible to reduce or eliminate them. A test stand has been developed at Virginia Tech to measure the vibrations of a 3.9 liter diesel engine stock turbocharger with both stock floating ring journal bearings and also custom design fixed geometry bearings. Vibration spectrum content clearly identifies the shaft instabilities and provides the basis for additional evaluation of future improved bearing design modifications. The current results, for custom fixed journal bearings, have clearly revealed a distinct jump with associated shift in the spectrum frequency content. This paper will document the recent tests of custom design fluid film bearings that have experienced this nonlinear jump condition.

The Experimental Research on Friction and Wear of the New Type Rock Bit Floating Ring Journal Bearing

A new type rock bit floating ring journal bearing is designed to solve the current problems of large heat, excessive wear and short life of rock bit journal bearing in high-speed and heavy-loads conditions, and the experimental research on friction moment, temperature rising and friction loss of bearings are carried out in different parameters and different working conditions. The experimental results show that the floating ring speed is changed because of the influence of loads and cone speed, the mean speed of floating ring remains relatively constant when the loads and the cone speed are constant and the speed of floating ring slows down as the speed increases, the inner and outer clearance of rock bit floating ring journal bearing have much effect on the speed of floating ring, the bearing life can significantly extend when the inner clearance is 0.058-0.064 and the outer clearance is 0.024-0.030, the rock bit floating ring journal bearing have more excellent tribological properties compared to the traditional thrust bearings and can replace the silver mangansese alloy slot currently used for the thrust bearings. The research provides important basis for further develop working performance research of rock bit floating ring journal bearing and design the new type rock bit floating ring journal bearing.

OPERATING CHARACTERISTICS OF POROUS FLOATING – RING JOURNAL BEARINGS OPERATING WITH AN IMPROVED BOUNDARY CONDITIONS

The static characteristics of porous floating ring journal bearing under hydrodynamic lubrication condition when operating with an improved boundary conditions are theoretically analyzed. An isothermal finite bearing theory was adopted during this analysis. The effect of different parameters, namely, permeability, geometrical dimensions of the ring and the bearing are considered. It was assumed that oil is supplied through the outside diameter of the bearing under low supply pressure. The angular extent of the oil – film formed in journal – ring and ring – bearing oil films was obtained by applying the integral momentum equation at the leading edge of the oil – film to define the beginning of the oil extent. While, the continuity of flow across the trailing edgewas used to define the end of the oil extent. Numerical results show that the bearing performance affected by different parameters namely, permeability, eccentricity ratios of inner and outer oil – film, the clearance ratios, and the radii ratios.

OPERATING CHARACTERISTICS OF POROUS FLOATING – RINGJOURNAL BEARINGS OPERATING WITH AN IMPROVEDBOUNDARY CONDITIONS

The static characteristics of porous floating ring journal bearing under hydrodynamic lubrication condition when operating with an improved boundary conditions are theoretically analyzed. An isothermal finite bearing theory was adopted during this analysis. The effect of different parameters, namely, permeability, geometrical dimensions of the ring and the bearing are considered. It was assumed that oil is supplied through the outside diameter of the bearing under low supply pressure. The angular extent of the oil – film formed in journal – ring and ring – bearing oil films was obtained by applying the integral momentum equation at the leading edge of the oil – film to define the beginning of the oil extent. While, the continuity of flow across the trailing edgewas used to define the end of the oil extent. Numerical results show that the bearing performance affected by different parameters namely, permeability, eccentricity ratios of inner and outer oil – film, the clearance ratios, and the radii ratios.

3045 ジャーナル軸受のスターブ潤滑 : 第4報,浮動リング軸受の安定性解析(S81-2 トライボロジーの基礎と応用(2),S81 トライボロジーの基礎と応用)

In floating ring journal bearings, there are two oil films outside and inside a floating ring. Lubricant to form the inner oil film is supplied through oil holes of the floating ring, then a lubricant starvation occurs sometimes in the inner film. This paper presents the effects of lubricant starvation on stability of the two types of floating ring journal bearings. From the results, it is found that the range of stability increases as the inner oil film starves and characteristics of semi floating bearings are improved as compared with full floating bearings.

An Analysis of the Circumferentially Grooved Floating Ring Journal Bearing Considering the Variation of Cavitation Region

The static and dynamic performances of a floating ring journal bearing with central circumferential grooves at the inner and outer films are obtained numerically using the isothermal lubrication theory. The Elrod algorithm implementing the Jakobsson-Floberg-Olsson cavitation boundary condition is adopted to predict cavitation regions in the inner and outer films more accurately than conventional analyses which use the half-Sommerfeld or Reynolds condition. The supply pressure drop in the circumferential groove of the inner film due to the rotation of the journal and ring is taken into account. It is shown that lubricant supply pressure has a significant influence on the static and dynamic performances of the bearing since it is closely related to the extent of the cavitation region. When the supply pressure is low and the journal speed is high, the supply pressure drop results in severe starvation of the lubricant in the inner film and affects the overall performance of the bearing remarkably.

Experimental and Analytical Research on Floating-Ring Bearings for Engine Applications

This study deals with whether floating-ring journal bearings can be applied to engine bearings or not. The performance of floating-ring journal bearings with nonstationary load is analyzed. The main bearings of a S195 4-stroke diesel engine are replaced by floating-ring bearings and an experiment is carried out with success. After the engine starting, the ring lifts off when crankshaft speeds approach seven hundred and forty rpm. The ring maintains its rotation until crankshaft speeds decrease to two hundred rpm, during its deceleration to a stop. Once the ring lifts off it remains in normal working order. It is possible for floating-ring bearings to be used in engines where the load is nonstationary. It is hoped that a further reduction in the ring starting speed will be provided by lessening the difference between dynamic and static frictional coefficients in friction pair and an increase in lifetime will be provided by the floating-ring journal bearing.

Externally-Pressurized Gas-Lubricated Floating-Ring Porous Journal Bearings: Part 1: Steady State Analysis

A new type of gas-lubricated floating-ring journal bearing in which the fixed bearing and the ring are both porous, has been conceived and analysed, theoretically, for the steady state characteristics. Bearing characteristics are presented against two design parameters, namely, clearances ratio and permeability parameter. The comparison of these characteristics with those of externally-pressurized plain porous journal bearings shows that the new bearing represents, with its steady state performance, a distinctly advanced bearing design.

Load Carrying Efficiency of Floating Ring Journal Bearings

Floating ring bearings are compared to single film journal bearings over the full range from laminar to turbulent conditions in the films. Isothermal conditions are assumed. Assuming each type carries the same external load and operates at the same eccentricity ratio as determined by the Capacity Number, reductions in the power loss required range from 31 to 64 percent when the clearance ratio C0/(C1 + C2) is held constant and the length is shortened, and from 42 to 63 percent when the length ratio L0/L is held constant and the clearance ratio C0/(C1 + C2) is reduced. Equilibrium ring speeds range from ω0/3 to 0.45 ω0.

On The Steady State and Dynamic Performance Characteristics of Floating Ring Bearings

An analysis of the steady state and dynamic characteristics of floating ring journal bearings has been performed. The stability characteristics of the bearing, based on linear theory, are given. The transient problem, in which the equations of motion for the bearing system are integrated in real time was studied. The effect of using finite bearing theory rather than the short bearing assumption was examined. Among the significant findings of this study is the existence of limit cycles in the regions of instability predicted by linear theory. Such results explain the superior stability characteristics of the floating ring bearing in high speed applications. An understanding of this nonlinear behavior, serves as the basis for new and rational criteria for the design of floating ring bearings.

Floating ring journal bearings: theory, design and optimization

The performance characteristics and design data for journal bearings with a precise floating ring inserted between the rotating journal and a rigid housing are investigated theoretically. Based on convenient boundary conditions, a theory has been developed to predict the floating ring behaviour. Performance charts are presented with curves provided with optimum design areas to help in practical design applications. Induced ring speed, hydrodynamic behaviour, oil film variation, load capacity and frictional drag could thus be analytically or graphically determined. Results indicate that the ring dimensions are a dominant factor in deciding the final bearing behaviour and that the oil film thickness between the ring and the housing is much thinner than that between the journal and the ring. The floating ring bearing showed less frictional power loss than a fixed sleeve bearing, but this may have been achieved at the expense of the load capacity.

Analysis of Dynamically Loaded Floating-Ring Bearings for Automotive Applications

This study deals with the frictional performance of dynamically loaded floating-ring journal bearings and investigates their feasibility for automotive applications. An analysis of the performance of floating-ring journal bearings in conducted. The bearing loads and speeds considered simulate those experienced in automotive engines. The potential contribution of the floating-ring design concept to reduced engine friction is assessed, and its compliance with current bearing durability criteria is evaluated. The results indicate that the adoption of the floating-ring design concept has the potential for reducing power loss in automotive engine bearings. It is shown that this can be accomplished without violating minimum film thickness constraints currently accepted as criteria for successful engine bearing operation.

The Effect of Variable Viscosity on the Stability of Plain Journal Bearings and Floating-Ring Journal Bearings

A theoretical analysis including linear perturbation is presented, investigating the stability against fractional frequency whirl (“oil whip”) for a symmetrical rotor supported in plain journal bearings or in floating-ring journal bearings operating with an incompressible lubricant under laminar fluid film flow conditions. In order to improve the conventional theoretical model of the bearing behavior, emphasis is put on the effect on stability of the considerable viscosity gradient which can arise in the bearing film due to film friction. The results are presented in the form of design data diagrams for the two bearing types. In the area of practical interest, the average effect on stability arising from the consideration of the viscosity gradient can be characterized as moderate. Concerning the floating-ring bearing superior stability characteristics are obtained primarily from correct choice of clearance ratio.

Unbalance Vibration of a Rotor-Bearing System Supported by Floating-Ring Journal Bearings

This paper presents an analytical solution for floating-ring journal bearing and a theretical analysis of unbalance vibration of a rotor-bearing system. Theoretical solutions for fluid film force, friction coefficient and stifness and damping coefficients are derived. The effect of a floating-ring journal bearing on unbalance vibrations of a symmetrical rotor-bearing system and some design recommendations for optimum bearing dimensions are discussed.

浮動ブシュ軸受でささえられた回転軸系の不つりあい振動

浮動ブシュ軸受でささえられた回転軸系の不つりあい振動

Steady-state and dynamic properties of the floating-ring journal bearing. (67-Lub-13) : F. K. Orcutt and C. W. Ng, pp. 243–253; 15 figs., 8 refs.

Steady-state and dynamic properties of the floating-ring journal bearing. (67-Lub-13) : F. K. Orcutt and C. W. Ng, pp. 243–253; 15 figs., 8 refs.

Steady-state and dynamic properties of the floating-ring journal bearing: Orcutt, F. K. and Ng, C. W. Transactions of the American Society of Mechanical Engineers, Journal of Lubrication Technology, Vol 90, Series F, No 1 (January 1968) p243

Steady-state and dynamic properties of the floating-ring journal bearing: Orcutt, F. K. and Ng, C. W. Transactions of the American Society of Mechanical Engineers, Journal of Lubrication Technology, Vol 90, Series F, No 1 (January 1968) p243