Showing papers on "Fluid bearing published in 1983"

Dynamic pressure type fluid bearing device

Abstract: A dynamic pressure type fluid bearing device including a housing having a bearing hole, a shaft rotatably provided in this bearing hole, and a thrust bearing member attached to an end of the housing, wherein a groove is provided in either the shaft or the bearing hole, another groove is provided in the contacting surface between the thrust bearing member and the shaft, a ventilation flute to communicate with the atmosphere is provided in the contacting surface between the thrust bearing member and the housing, and a lubricant is charged around the groove, so that the lubricant is prevented from flowing out due to changes in the atmospheric pressure or environment.

The Effect of Fluid Inertia in Squeeze Film Damper Bearings: A Heuristic and Physical Description

Abstract: Fluid inertia forces are comparable to viscous forces in squeeze film dampers in the range of many practical applications. This statement appears to contradict the commonly held view in hydrodynamic lubrication that inertia effects are small. Upon closer inspection, the latter is true for predominantly sliding (rather than squeezing) flow bearings.The basic equations of hydrodynamic lubrication flow are developed, including the inertia terms. The appropriate orders of magnitude of the viscous and inertia terms are evaluated and compared, for journal bearings and for squeeze film dampers. Exact equations for various limiting cases are presented: low eccentricity, high and low Reynolds number. The asymptotic behavior is surprisingly similar in all cases. Due to inertia, the damper force may shift 90° forward from its purely viscous location. Inertia forces are evaluated for typical damper conditions.The effect of turbulence in squeeze film dampers is also discussed. On physical grounds it is argued that the transition occurs at much higher Reynolds numbers than the usual lubrication turbulence models predict.Copyright © 1983 by ASME

Hydrodynamic bearing assembly

Abstract: The invention relates to a hydrodynamic bearing assembly in which a relatively broad bearing is divided into two bearings (2, 3) placed axially side by side. Both bearings are connected together to an inner bearing member (1) which is mounted to swivel universally over a spherical sector surface (16) in a cylindrical bore (18) of a surrounding housing. Between the bearing surfaces of both bearings (2, 3) there is provided in the bearing bore (6) a flowing fluid medium passage shared by the bearings, such as an annular groove (10). Through this passage the outlet flow area for the flowing fluid medium is doubled and length of the flow path in the bearing bore (6) reduced by one-half. Concurrently, a more perfect load pressure equalization is achieved on both bearings (2, 3) owing to the ball-joint-type universal bearing arrangement between the inner bearing member (1) and the housing (20).

Optimum design of one-dimensional journal bearings

Abstract: When two surfaces in relative motion are separated by a thin layer of viscous fluid, they are kept apart by the pressure generated in the fluid film due to viscous forces. The magnitude of the resultant of this pressure is the load capacity of the bearing. We find the shape of a one-dimensional journal bearing which supports the greatest load.

Dynamic Behavior of a Journal Bearing in a Planet Gear

Abstract: The dynamic analysis of the journal bearing which supports the planets of an epicyclic gear stage is described. The analysis includes an assessment of the damping characteristics of the bearing, the stability, and the response of the planet to gear mesh interactions between the sun, the planet, and the ring gear. A digital program was developed which provides the numerical solution of the equations of motion by forward integration in time. The full nonlinear expressions have been used for both the hydrodynamic bearing forces and the gear mesh interaction forces. Centrifugal and Coriolis effects due to the planetary motion are taken into account. Numerical results for a PT6 reduction gearbox indicate that the bearing is highly stable and not adversely affected by gear mesh excitations.

Predicted and experimental performance of large-bore high-speed ball and roller bearings.

Abstract: The values of inner and outer race temperature, cage speed, and heat transferred to the lubricant or bearing power loss, calculated using the computer programs Shaberth and Cybean, with the corresponding experimental data for the large bore ball and roller bearings were compared. After the development of computer program, it is important that values calculated using such program are compared with actual bearing performance data to assess the programs predictive capability. Several comprehensive computer programs currently in use are capable of predicting rolling bearing operating and performance characteristics. These programs accept input data of bearing internal geometry, bearing material and lubricant properties, and bearing operating conditions. The programs solve several sets of equations that characterize rolling element bearings. The output produced typically consists of rolling element loads and Hertz stresses, operating contact angles, component speed, heat generation, local temperatures, bearing fatigue life, and power loss. Two of these programs, Shaberth and Cybean were developed.

Applications of film thickness equations

Abstract: A number of applications of elastohydrodynamic film thickness expressions were considered. The motion of a steel ball over steel surfaces presenting varying degrees of conformity was examined. The equation for minimum film thickness in elliptical conjunctions under elastohydrodynamic conditions was applied to roller and ball bearings. An involute gear was also introduced, it was again found that the elliptical conjunction expression yielded a conservative estimate of the minimum film thickness. Continuously variable-speed drives like the Perbury gear, which present truly elliptical elastohydrodynamic conjunctions, are favored increasingly in mobile and static machinery. A representative elastohydrodynamic condition for this class of machinery is considered for power transmission equipment. The possibility of elastohydrodynamic films of water or oil forming between locomotive wheels and rails is examined. The important subject of traction on the railways is attracting considerable attention in various countries at the present time. The final example of a synovial joint introduced the equation developed for isoviscous-elastic regimes of lubrication.

Interactive Mechanisms of Sliding-Surface Bearings.

Abstract: : This report adapts the theory of hydrodynamic lubrication to include surface roughness effects and asperity interactions. This theory becomes a means of studying the behavior of sliding-surface bearings in transition from hydrodynamic into mixed lubrication. A model problem, in the form of a crowned tilt-pad bearing with longitudinal roughness, was solved. In treating the model problem, end-leakage was neglected and a constant lubricant viscosity was assumed. Use of numerical computational methods could readily remove these restrictions. In real operating environments of ship components and shipboard machinery, the lubrication process is made more complex by thermoelastohydrodynamic effects and the likely occurrence of film striation. Because these complicated phenomena are only qualitatively understood, no adequate or comprehensive method exists for designing critical machine components such as face seals, elastomeric sterntube bearings, rudder stock, diving plane bearings, and main shaft thrust bearings. This report is part of a comprehensive plan to develop a better understanding of the interactive wear mechanisms of sliding surfaces. The theoretical basis is the application of Reynold's equation to the mixed lubrication regime. A closed-form solution of Reynold's equation applied to a crowned tilt-pad thrust bearing in transition from the hydrodynamic to the mixed lubrication region is presented to demonstrate some of the principles of this approach. The concepts developed are applicable to a wide variety of bearings and seals.