Showing papers on "Thrust bearing published in 2003"

A Laser Surface Textured Parallel Thrust Bearing

Abstract: The potential use of a new technology of laser surface texturing (LST) in parallel thrust bearings is theoretically investigated. The surface texture has the form of micro-dimples with pre-selected diameter, depth, and area density. It can be applied to only a portion of the bearing area (partial LST) or the full bearing area (full LST). Optimum parameters of the dimples, and best LST mode, are found in order to obtain maximum load carrying capacity for a thrust bearing having parallel mating surfaces. A comparison is made with optimum linear and stepped sliders showing that parallel LST sliders can provide similar load carrying capacity. Scheduled for Presentation at the 58th Annual Meeting in New York City April 28–May 1, 2003

Spindle motor, and disk drive utilizing the spindle motor

Abstract: Low-profile spindle motor whose entire shaft length is utilized to configure, along an encompassing sleeve, a radial dynamic-pressure bearing section. One end of the shaft is unitary with the rotor, and a cover member closes the other end. Between the sleeve upper-end face and the rotor undersurface a thrust bearing section is configured. Micro-gaps are formed continuing between the sleeve upper-end face and the rotor undersurface; the sleeve inner-circumferential surface and the shaft outer-circumferential surface; and the cover member inner face and the shaft end face, where an axial support section is established. Oil continuously fills the micro-gaps without interruption, configuring a fully filled hydrodynamic bearing structure. Hydrodynamic pressure-generating grooves in the radial bearing section are configured so that no axial flow is induced in the oil, and in the thrust bearing so that lift pressure, balanced by hydrostatic pressure in the axial support section, is imparted in the oil.

Spindle motor and disk drive furnished therewith

Abstract: In a spindle motor utilizing dynamic-pressure bearings having a full-fill structure, a bearing configuration that balances and sustains at or above atmospheric pressure the internal pressure of the bearing oil. Thrust and radial bearing sections are configured within oil-filled bearing clearances in between the rotor, the shaft, and a shaft-encompassing hollow bearing member. A communicating passage one end of which opens on, radially inwardly along, the thrust bearing section is formed in the bearing member. Either axial ends of the bearing clearance in between the bearing member and shaft communicate through the passage. The communicating passage enables the oil to redistribute itself within the bearing clearances. Pressure difference between the axial upper and lower ends of the oil retained in between the bearing member and the shaft is compensated through the communicating passage, preventing incidents of negative pressure within the oil and of over-lift on the rotor.

Test Results for PTFE-Faced Thrust Pads, With Direct Comparison Against Babbitt-Faced Pads and Correlation With Analysis

Abstract: The use of PTFE-faced pads in large vertical axis hydro-generators was pioneered in Russia in the 1970s, prompted by a series of failures of conventional babbitt-faced bearings. Some advantages claimed include higher specific loading, lower power loss and the omission of oil-lift facilities. There is strong interest in the Industry concerning this material, but limited data are available on actual performance. Some results from extensive testing of PTFE-faced pads are given, for two sizes of pad. These are compared directly size-for-size with results for babbitt bearings of nominally the same area. The power losses for the two types of bearing were found to be almost identical. Some of the effects observed during testing are described and discussed, including the effect of creep. The test results are compared with predictions using the GENMAT analysis software A method of allowing for creep in numerical modeling is discussed.

Development of High-Speed Gas Bearings for High-Power Density Microdevices

Abstract: A 4.2-mm diameter silicon rotor has been operated in a controlled and sustained manner at rotational speeds greater than 1.3 million rpm and power levels approaching 5 W. The rotor, supported by hydrostatic journal and thrust gas bearings, is driven by an air turbine. This turbomachinery/bearing test device was fabricated from single-crystal silicon wafers using micro-fabrication etching and bonding techniques. We believe this device is the first micro-machine to operate at a circumferential tip speed of over 300 meters per second, comparable to conventional macroscale turbomachinery, and necessary for achieving high levels of power density in micro-turbomachinery and micro-electrostatic/ electromagnetic devices. To achieve this level of peripheral speed, micro-fabricated rotors require stable, low-friction bearings for support. Due to the small scale of these devices as well as fabrication constraints that limit the bearing aspect ratio, the design regime is well outside that of more conventional devices. This paper focuses on bearing design and test, and rotordynamic issues for high-speed high-power micro-fabricated devices.

A unified and simplified treatment of the non-linear equilibrium problem of double-row rolling bearings. Part 1: Rolling bearing model:

Abstract: To increase the rigidity of bearings-shaft systems, the shaft is often supported by a series of double-row rolling bearings. Little work on multiple-row rolling bearings has been published. A comprehensive model is proposed which permits the determination of the internal interactions. The total elastic deflection between bearing rings is described using a vector-and-matrix method. A variety of double-row rolling bearing types are analysed, such as tapered roller bearing, cylindrical roller bearing, spherical roller bearing, self-aligning ball bearings and angular contact ball bearing. The basic internal geometry (including the internal clearance) and the effect of the initial preload (in term of the initial axial compression) are considered.

Dynamic bearing device and method for making same

Abstract: The thrust member is inserted into the inner circumferential surface of the housing, to make the end face of the thrust member contact with the lower side end face of the flange portion, and at the same time, to make the upper side end face of the flange portion contact with the lower side end face of the bearing sleeve. This stated is that the thrust bearing gap is zero. Then, the thrust member is made to relatively move with respect to the housing and the bearing sleeve in the axial direction together with the axis member, with a dimension δ(δ=δ1+δ2) that is equivalent to the sum of the thrust bearing gap (size is δ1) of the first thrust bearing portion and the thrust bearing gap (size is δ2) of the second thrust bearing portion. Then, as the thrust member is fixed to the housing at that position, the predetermined thrust bearing gap δ(δ=δ1+δ2) is formed.

Hydrodynamic Bearing Device

Abstract: A hydrodynamic bearing device with reduced costs is provided. A housing with a bearing sleeve housed therein is formed by drawing. A cup shaped thrust member is positioned in a bottom part of the housing, and by bringing this thrust member into contact with a lower end surface of the bearing sleeve, the widths of thrust bearing gaps within first and second thrust bearing parts are set to prescribed values.

Foil bearing and spindle device using the same

Abstract: A foil bearing is provided, which is simple in structure, has a large load capacity and a large damping capability and can therefore allow a rotary shaft having a large unbalance as compared with the conventional bearing to be driven stably at a high speed. A spindle device utilizing such foil bearing is also provided, which is designed to increase the permissible amount of unbalance and also to have a light-weight feature. Each of the foil bearings 504 and 505 includes an elastic member 2 prepared from a wire net formed by braiding wires, and a thin bearing foil 3 supported by the elastic member 2 and defining an elastic bearing surface S. The respective foil bearing 504 and 505 is used at least as a radial bearing 504 in the spindle device including a rotary shaft 4 having a head mount 501 a, on which an atomizer head is mounted, and the radial and thrust bearings 504 and 505 for rotatably supporting the rotary shaft 4.

Control of self-excited vibration of a rotor system with active gas bearings

Abstract: This paper presents an experimental study on the active control of self-excited vibrations in a rotor-bearing system supported on a pair of externally pressurized thrust bearings in the axial direction and on actively controlled journal gas bearings in the radial direction. The active journal gas bearings used are of the tilting-pad type with one traditional passive pad and two active pads with embedded piezoelectric actuators. Feedback control systems are constructed with gap sensors for measuring the vibration of the rotor, embedded piezoelectric actuators, and PID controllers. The experimental results show that the self-excited vibration can be effectively suppressed with the designed feedback control system, if the gains of the PID controllers are properly tuned.

Mixed Lubrication of Coupled Journal-Thrust-Bearing Systems Including Mass Conserving Cavitation

Abstract: A mixed lubrication model is developed to investigate the lubrication of coupled journal-thrust-bearing systems The governing equations are mapped into a computational domain with a conformal mapping technique developed in a previous study by Wang et al (2002) In order to study the influence of the boundary conditions on the performance of the bearing system, either the Reynolds boundary conditions or the JFO's mass conserving conditions are applied to the governing Reynolds equations The performance of a typical coupled journal-thrust bearing system is numerically investigated and the effects of viscosity, misalignment angle and feeding scheme are discussed

Rotor bearing arrangement for transferring rotor bending moments and torques for wind power plant has hub directly connected to inner ring of radial bearing or/and to bearing stiffening ring

Abstract: The arrangement has a rotor hub with at least one rotor blade fixed into it and a large roller bearing carrying the rotor, preferably a radial bearing, especially a conical roller bearing, with a fixed outer ring and a planar gear mechanism arranged after it. The hub is directly connector to the inner ring of the radial bearing or/and with a bearing stiffening ring.

Evaluating thermal performance of a PTFE-faced tilting pad thrust bearing

Abstract: This paper compares and analyses operating characteristics of equalizing tilting pad thrust bearings with babbitt and polytetrafluoroethylene (PTFE) composite facings. Each bearing arrangement included six pads with an outer diameter of 228.6 mm and 60 percent offset. The babbitted bearing was typical of design in general use. A PTFE composite was applied instead of the babbitt to a similar bearing. Bearings were tested at different load-speed combinations in the fully flooded mode. Pad temperature distributions, collar temperatures and bearing friction torque were continuously measured. Test results show that the PTFE composite provides excellent thermal insulation so that pad thermal crowning is eliminated. PTFE-faced bearings operate with lower power loss and slightly higher collar temperatures compared to similar babbitted bearings.

Spiral Orbit Tribometry — Part I: Description of the Tribometer

Abstract: A new rolling contact tribometer based on a planar thrust bearing geometry is described. The bearing 'races' are flat plates that drive a ball into a near-circular, spiral path. The spiraling ball is returned to its initial radius each revolution around the race by a 'guide plate' backed by a force transducer. The motions of the ball are analyzed and the force exerted by the ball on the guide plate is related to the friction coefficient of the system. The experimental characteristics of the system are presented and the system is shown to exhibit the behavior expected for a tribometer.

Determination of Rolling-Element Fatigue Life From Computer Generated Bearing Tests

Abstract: Two types of rolling-element bearings representing radial loaded and thrust loaded bearings were used for this study. Three hundred forty (340) virtual bearing sets totaling 31400 bearings were randomly assembled and tested by Monte Carlo (random) number generation. The Monte Carlo results were compared with endurance data from 51 bearing sets comprising 5321 bearings. A simple algebraic relation was established for the upper and lower L(sub 10) life limits as function of number of bearings failed for any bearing geometry. There is a fifty percent (50 percent) probability that the resultant bearing life will be less than that calculated. The maximum and minimum variation between the bearing resultant life and the calculated life correlate with the 90-percent confidence limits for a Weibull slope of 1.5. The calculated lives for bearings using a load-life exponent p of 4 for ball bearings and 5 for roller bearings correlated with the Monte Carlo generated bearing lives and the bearing data. STLE life factors for bearing steel and processing provide a reasonable accounting for differences between bearing life data and calculated life. Variations in Weibull slope from the Monte Carlo testing and bearing data correlated. There was excellent agreement between percent of individual components failed from Monte Carlo simulation and that predicted.

Effect of Thrust Magnetic Bearing on Stability and Bifurcation of a Flexible Rotor Active Magnetic Bearing System

Abstract: This paper is concerned with the effect of a thrust active magnetic bearing (TAMB) on the stability and bifurcation of an active magnetic bearing rotor system (AMBRS). The shaft is flexible and modeled by using the finite element method that can take the effects of inertia and shear into consideration. The model is reduced by a component mode synthesis method, which can conveniently account for nonlinear magnetic forces and moments of the bearing. Then the system equations are obtained by combining the equations of the reduced mechanical system and the equations of the decentralized PID controllers. This study focuses on the influence of nonlinearities on the stability and bifurcation of T periodic motion of the AMBRS subjected to the influences of both journal and thrust active magnetic bearings and mass eccentricity simultaneously. In the stability analysis, only periodic motion is investigated. The periodic motions and their stability margins are obtained by using shooting method and path-following technique. The local stability and bifurcation behaviors of periodic motions are obtained by using Floquet theory. The results indicate that the TAMB and mass eccentricity have great influence on nonlinear stability and bifurcation of the T periodic motion of system, cause the spillover of system nonlinear dynamics and degradation of stability and bifurcation of T periodic motion. Therefore, sufficient attention should be paid to these factors in the analysis and design of a flexible rotor system equipped with both journal and thrust magnetic bearings in order to ensure system reliability.

Single thrust-journal bearing cup fluid dynamic bearing motor

Abstract: A fluid dynamic bearing motor is described. In one embodiment, the fluid dynamic bearing motor includes a stationary member and a rotating member. The motor further includes a fluid dynamic thrust bearing disposed along an axial surface of a sleeve. The thrust bearing is configured to axially support the relative rotation of the rotating member and the stationary member and to pump bearing fluid towards a corner of the sleeve. The motor also includes a fluid dynamic journal bearing disposed radially inboard of the thrust bearing along a radial surface of the sleeve, where the radial surface is adjacent to the axial surface. The journal bearing is configured to radially support the relative rotation of the rotating member and the stationary member and to pump bearing fluid to the corner of the sleeve.

Differential for motor vehicles has drive shaft with common bearing bush for first drive shaft bearing and differential housing bearing

Abstract: The differential has a differential housing (2) with differential wheel (5) meshing with a pulley (6) of a drive shaft (7). The drive shaft has a common bearing bush (8) for a first bearing of the drive shaft, which is formed as a shaft bearing (7.1), and the housing bearing (2.1) of the differential housing. Shaft bearing and/or housing bearing are formed as slide or roller bearings, with at least one bearing pair in X-arrangement.

Some Effects of Start-Up and Shut-Down on Thrust Bearing Assemblies in Hydro-Generators

Abstract: The modernization of hydro-generators can involve the analysis of many different manufacturers designs of thrust bearings. Recent designs of bearing in common use are very reliable. but when failures do occur, it is often with older machines and within the first few minutes of start-up. This paper is a result of general design studies of various thrust bearing configurations subjected to transient operating conditions, It is shown that transient effects can induce an 'overshoot' of thermal deformation which can become unstable, leading to 'thermal ratchetting.' Examples are given of pacts of various. manufacturers bearings that have been subjected to this mechanism. Results from operating turbines. basic studies and measurements of the thermal bending of plates indicate that a peak deflection occurs well before thermal equilibrium is attained. The peaking phenomenon may be obscured in some designs or in cases where the run-up is gradual. The beneficial effects of using an oil-lift system during start-up are described. During shut-down it is important that the contact of hot, crowned pads against the runner be prevented. Minimum times for operation of the lift system are suggested, based on the thickness of the pads.

Disk drive spindle motor with radial inward thrust area annular prutruding portion and bearing member communicating passage

Abstract: In a spindle motor utilizing dynamic-pressure bearings having a full-fill structure, a bearing configuration that balances and sustains at or above atmospheric pressure the internal pressure of the bearing oil. Thrust and radial bearing sections are configured within oil-filled bearing clearances in between the rotor, the shaft, and a shaft-encompassing hollow bearing member. A communicating passage one end of which opens on, radially inwardly along, the thrust bearing section is formed in the bearing member. Either axial ends of the bearing clearance in between the bearing member and shaft communicate through the passage. The communicating passage enables the oil to redistribute itself within the bearing clearances. Pressure difference between the axial upper and lower ends of the oil retained in between the bearing member and the shaft is compensated through the communicating passage, preventing incidents of negative pressure within the oil and of over-lift on the rotor. And an annular protruding portion is formed on at least one of the end face of the bearing member and the flat face of the rotor at radially inward portion of the thrust bearing section.

Thin display device

Abstract: A position adjusting mechanism, a rotation-axle bearing mechanism, and a rotation-speed reduction mechanism for a flat display apparatus. The rotation-speed reduction mechanism comprises a position adjusting mechanism that includes one or more means for securely attaching a stand and a main body unit of the apparatus to one another, and a position adjusting means for adjusting the mounting position of the stand and main body unit. The rotation-axle bearing mechanism comprises a radial bearing and a thrust bearing for supporting a rotation axle between a display screen unit and the stand. The rotation-speed reduction mechanism reduces the speed of rotation between the display screen unit and the stand upon application of a rotation load exceeding a certain level.

Axial plunger type water hydraulic pump

Abstract: An axial direction piston type water hydraulic pump belongs to liquid volume changing machinery. The pump integrates the advantages of the valve distribution and end face distribution piston type water hydraulic pump, and reduces the radial dimension, reduces the weight, improve the specific power and volumetric efficiency, prolongs the using life. The utility model adopts flat valve distribution. The piston and the piston hole are axially and uniformly arranged on the circumference opposite to the main shaft. The reciprocating motion of the piston is realized by the inclined plate and central spring. The piston, piston ball-end and the sliding shoe are provided with central holes. The back end cover, cylinder body, pump shell and front end cover are respectively provided with flowing channel. A ring cavity chamber is arranged on the central part of the thrust bearing. The main shaft is provided with axial flow channel therein and a radial flow channel on the surface. Each of the channels is connected with all of the friction pair and directly lubricatess and cools the friction pair with water. By adopting corrosion resistant alloy, ceramic, or polymer composite material, the major friction pair can effectively reduce friction and prolong working life. The pump is provided with small volume, light weight, high volumetric efficiency, big specific power, long working life, is suitable for the low viscosity hydraulic medium, such as seawater, freshwater, high water base, etc.

Horizontal Centrifugal Pumping System

Abstract: The present invention provides a thrust bearing assembly and a horizontal skid utilized in a horizontal pumping system In one embodiment, the thrust bearing assembly comprises a cylindrical open housing, at least one radial ball bearing, at least one rotating seal, and at least one axial thrust bearing The axial thrust bearing does not have to be completely submerged in lubricant

Inboard thrust surface fluid recirculation pump

Abstract: An inboard thrust surface is provided for a spindle motor that maintains fluid flow through a journal bearing and generates an added offset pressure to avoid any subambient pressure within a journal. In an aspect, journal bearing asymmetry is minimized or eliminated and axial span is increased between journal bearings, reducing wobble or run-out between relatively rotating components. In another aspect, journal axial length is decreased for low profile disc drive memory systems and other spindle motors. In an aspect, two separate thrust surfaces provide an axial force in the same direction, opposing an axial bias force created by interaction of a stator and a magnet, and minimizing power consumption.

Bearing assembly with fluid circuit for delivery of lubricating fluid between bearing surfaces

Abstract: An integral thrust/journal bearing assembly, e.g., useable in a turbocharger is provided. The assembly includes a journal bearing configured to operate at a first mechanical load. The assembly further includes a thrust bearing including a thrust bearing face. The thrust bearing may be configured to operate at a second mechanical load different than the first mechanical load. A fluid circuit that includes parallel branches is provided within the integral bearing assembly for delivering parallel flows of lubricating fluid to the thrust bearing face and the journal bearing.

Tranmission devices, for group vehicles and move particularly for motors-cars

Abstract: The epicyclic train is able to operate as a speed reducing gear when sun-wheel (5) is stuck by a one-way clutch (8), and in direct drive when clutch (10) is engaged. The whole coupling and control structure for the ratio change is essentially grouped on the sun-wheel element (5) which is slidingly movable and integral with an inverter control means (111) which engages brake (9) when disengaging clutch (10), and conversely. The brake (9) is mounted mechanically in parallel with a one way clutch (8), and allows speed reducing operation when the torque applied to the input shaft (31) is a retarding torque. The one-way clutch is mounted in parallel with an axially unslidable bearing (54) between a stator shaft (21) and a support (51) coupled for common rotation with and mutual slidability with respect to the sun-wheel element (5). For actuation of the control member (111) there is provide an hydraulic actuator (116), spring (114), and involvement of the helical teeth axial thrust (F1, F2). Useful for simplifying the control, keeping a possibility of other selective couplings, allowing other operating conditions, with the other rotary elements (6, 7) of the train, and avoiding the thrust bearings.

Spool bearing with asymmetric sealing

Abstract: A spindle motor is provided comprising a fixed shaft capable of being fastened at either end to the base and cover of the disc drive The hub which rotates around the disc drive is supported for rotation by a journal bearing and thrust bearing, with the thrust bearing grooved surfaces being defined in gaps immediately adjacent the ends of the journal bearing A fluid recirculation path is provided through the rotating sleeve connecting the surfaces adjacent the thrust bearings, with the asymmetry which provides the fluid circulation either being inherently present due to tolerances in the bearing and groove design, or specifically provided by asymmetry in the bearing groove pattern An asymmetric sealing system employs a pumping seal adjacent a radial end of the thrust plate near the base of the housing, and a shorter pumping seal defined adjacent a radial end of the thrust plate distal from the base

Power roller unit for toroidal-type continuously-variable transmission

Abstract: A power roller unit for a toroidal-type continuously variable transmission, has: a trunnion including a support plate portion, a pair of bent wall portions, two pivot shafts, and a connecting member; a displacement shaft; a power roller; a thrust ball bearing including an outer ring, a ball, and a retainer; a thrust bearing, wherein the thrust bearing is held by a hold portion disposed in the support plate portion, and wherein, where the distance between the small end face of the power roller and the connecting member is expressed as a, the distance between the outer ring and the opposed surface of the hold portion opposed to the outer ring is expressed as b, and the thickness of the thrust bearing is expressed as c, the sum of a and b is set smaller than c.