Showing papers on "Thrust bearing published in 2008"

Fundamentals of Tribology

Abstract: Description of Surfaces Contact Mechanics Dry Contact Friction Lubricant Rheology Principles of Hydrodynamics Thermohydrodynamics Elastohydrodynamics Thrust Bearings Journal Bearings Externally Pressurized Bearings Hydrostatic Bearings Aerostatic Bearings Ball and Rolling Element Bearings Fatigue Wear Adhesion Transient Elastohydrodynamics Valve Trains Pistons Biotribology of Natural Joints Joint Replacements Nanotribology Van Der Waal's Forces Electrostatics Meniscus Action Solvation Hydration MEMS Hard Disk Drives.

Centrifugal rotary blood pump with impeller having a hydrodynamic thrust bearing surface

Abstract: A rotary blood pump may include one or more motor stators overlying exterior surfaces of a wall defining a pumping chamber. A rotatable impeller within the pumping chamber may have a hydrodynamic thrust bearing surface adapted to constrain a position of the impeller along an axis of rotation relative to the wall when the impeller is rotating about the axis of rotation. The impeller position may then be constrained without requiring a constant polarity magnetic force to be applied in the axial direction from a fixed position of the housing.

Optimization of Groove Geometry for Thrust Air Bearing to Maximize Bearing Stiffness

Abstract: Hydrodynamic gas film bearings are widely used for very-high-speed, lightly loaded rotating machinery. In the design of hydrodynamic gas film bearings, it is of cardinal importance to enhance the stiffness of gas films to minimize vibration due to external excitations. Among various types of hydrodynamic gas film thrust bearings, grooved bearings have an advantage of high stiffness and load-carrying capacity, but the stiffness of the bearings strongly depends on groove geometry. Therefore, when the groove geometry is suitably designed, it is expected to considerably improve the stability characteristics of the bearings. However, conventional bearing geometries are based on a fixed logarithmic spiral curve, and there is no literature on how to effectively change the groove geometry to drastically improve the bearing characteristics. In this paper, the entirely new optimum design methodology, in which the groove geometry can be flexibly changed by using the spline function, is presented to maximize the stiffness of gas films for grooved thrust bearings. The effectiveness of the methodology is experimentally verified.

Basic Characteristics of an Active Thrust Magnetic Bearing With a Cylindrical Rotor Core

Abstract: Magnetic bearings, which can suspend rotor shafts by electromagnetic force without mechanical contacts and lubrication, have been developed and commercialized. In the various types of magnetic bearings, thrust magnetic bearings with thrust disks are generally used for active suspension control of thrust direction. However, the large thrust disks of the thrust magnetic bearings have caused various problems. Therefore, this paper proposes a novel structure of an active thrust magnetic bearing using a cylindrical rotor core without the large thrust disk, and it is shown with 3-D-FEA and experiment that the proposed thrust magnetic bearing with the cylindrical rotor core is effective in producing thrust force.

Screw fluid machine

Abstract: A screw compressor has a balance bearing whose outer ring is movable relative to the casing. A balance piston divides a balance cylinder into a high pressure fluid chamber and a low pressure fluid chamber, and movement of the piston in the balance cylinder is transmitted to the outer ring of the balance bearing. The high pressure fluid chamber and the low pressure fluid chamber are arranged such that higher pressure fluid in the high pressure fluid chamber urges the piston to press the outer ring of the balance bearing oppositely to a spring and toward the main thrust bearing, and lower pressure fluid in the low pressure fluid chamber urges the piston to press the outer ring of the balance bearing away from the main thrust bearing.

Optimization of Groove Geometry for a Thrust Air Bearing According to Various Objective Functions

Abstract: Grooved thrust air bearings are widely used to support high-speed, low-loaded shafts in many rotating systems because of their low friction, noiseless operation, and simple structure. Several types of groove geometries, such as straight line, spiral, and herringbone, are commonly used in actual applications. Among them the spiral groove is mainly used. However, as far as the authors know, there is no theoretical evidence that the spiral groove is an optimized groove geometry in all possible groove geometries. This paper describes the optimum design for the groove geometry of thrust air bearings according to various objective functions, such as air film thickness, bearing torque, dynamic stiffness of air film, and combinations of same. In an optimum design, groove geometries are expressed by the third degrees of spline function, and sequential quadratic programming is used as the optimization method. We found that groove geometry optimizing air film thickness or friction torque takes the form of a spiral groove. The geometry optimizing the dynamic stiffness is the modified spiral groove. Some numerical results are compared with the measured data, and good agreements can be seen between them.Copyright © 2008 by ASME

Performance of hydrodynamic lubrication journal bearing with a slippage surface

Abstract: Purpose – The aim of this paper is to propose a design idea for an infinite journal bearing with the optimized slip zone on the bearing sleeve surface.Design/methodology/approach – The approach is to use finite element analysis and the quadratic programming algorithm to study the performance of the journal bearing with a slip zone on the sleeve surface. The fluid film pressure and slip velocity can be obtained in one solution step.Findings – A journal bearing with a slip zone on the sleeve surface produces many different advantages over the traditional journal bearing. Even in a parallel sliding gap there is still a considerable large load support, but a very low friction drag. The effect of the enhancement of such a slip wedge on the journal bearing performance is much greater at a small eccentricity ratio than at a large eccentricity ratio. Numerical analyses indicate that the location and size of the slip zone greatly affect the journal performance. When the eccentricity ratio ϵ=0.8, the maximum load s...

Centrifugal rotary blood pump

Abstract: A rotary blood pump may include one or more motor stators overlying exterior surfaces of a wall defining a pumping chamber. A rotatable impeller within the pumping chamber may have a hydrodynamic thrust bearing surface adapted to constrain a position of the impeller along an axis of rotation relative to the wall when the impeller is rotating about the axis of rotation. The impeller position may then be constrained without requiring a constant polarity magnetic force to be applied in the axial direction from a fixed position of the housing.

Multiple-row large roller bearing, especially axial radial bearing for the main arrangement of bearings of the rotor shaft of a wind power installation

Abstract: An axial radial bearing for a rotor shaft of a wind power installation, which has a vertical circular outer disk, inner ring arranged coaxially to the outer disk, and two circular shaft washers axially arranged on both sides of the outer disk. At least one row of rolling bodies, held at equal distances by a bearing cage, extends between the shaft washers and outer disk, forming the rolling bearings for receiving axial forces, while at least one other row of rolling bodies, optionally held at equal distances by another bearing cage, is arranged between the outer disk and inner ring, forming a third rolling bearing for receiving radial forces. The two rolling bearings for receiving radial forces are formed by two tapered roller bearings oriented towards the longitudinal axis of the bearing by the small front sides, or by a double-row angular ball bearing or by two axial ball bearings.

Observations and Location of Acoustic Emissions for a Naturally Degrading Rolling Element Thrust Bearing

Abstract: Acoustic Emission (AE) technology applied to condition monitoring is gaining acceptance as a useful complimentary tool. This article demonstrates the use of traditional AE parameters, the Enegry Index and Kolmogorov–Smirnov test (KS-test) to detect, locate, and monitor natural defect initiation and propagation in a conventional rolling element thrust bearing. To undertake this task a special purpose test-rig was built to allow for accelerated natural degradation of a bearing race. It is concluded that sub-surface initiation and subsequent crack propagation can be detected using a range of data analysis techniques on AE’s generated from natural degrading bearings. The article also investigates the source characterization on AE signals associated with such a bearing while in operation.

Thrust bearing applying interface sliding technology

Abstract: The invention is a thrust bearing using the interface slippage technology, and is characterized in that the bearing comprises a static and a moving flat panels that are parallel to each other; the gap between the static and the moving flat panels is filled with fluid lubricating oil; a coating layer II is arranged on part of the static flat panel; a coating layer I is arranged on the rest partof the static flat panel; a coating layer III is arranged on the surface of the moving flat panel, Therefore, a thrust bearing is formed by the two flat panels through a certain relative moving between the static flat panel and the moving flat panel, the coating layer I is a fluorocarbon coating layer, and the coating layer II and III are coatings of mica powder modified by silane coupling agents. The thrust bearing is simple in the bearing forming and has a certain carrying capacity, good anti-friction and wear-resistance without the need of processing the matching surface into a geometric shape. With simple and compact structure and small size and low production cost, the thrust bearing can replace the traditional fluid motive power lubrication thrust bearing for bearing purpose.

Device for testing elastic foil tablet transverse bearing departure rotary speed

Abstract: The invention relates to a device for measuring the takeoff rotating speed of the elastic foil thrust bearing, which comprises a drive system, a shaft journal part and a lubricating system, and a data acquisition system; the drive system is composed of an asynchronous motor and a frequency converter; the asynchronous motor is connected with one end of the shaft journal through a high-speed flexible shaft coupling; the shaft journal utilizes two rolling bearing holders to implement lubrication on the rolling bearing through an oil gas lubricating coupler; the data acquisition system is composed of a sensor, an amplifier and a computer; the data measured by the sensor can be collected by a acquisition card and be input in the computer for storage; the rotor is driven by the motor; the static load of the bearing can be changed by a charger, thereby the takeoff rotating speed of the foil bearing in different loads can be measured.

Contra-rotating propeller marine propulsion device

Abstract: The thrust load of an outer shaft (11) is received by a contra-rotating thrust bearing (40) provided in a boss (13a) of a front propeller (13) and transmitted to an inner shaft (12). The thrust load of both the outer shaft (11) and the inner shaft (12) is received by an inner shaft thrust bearing (41) provided on the bow side of a power transmission device (20A) and transmitted to a ship body (2). The rotational force of an outer shaft output shaft (24) is transmitted to the outer shaft (11) via a flexible shaft joint (19) (gear coupling (19A)). Thus, the thrust load of the outer shaft (11) is transmitted to the ship body (2) only via the inner shaft (12) without being directly transmitted to the ship body (2), and the axial displacement and angular displacement are allowed by the gear coupling (19), so that the influence of the displacement of the ship body on the shaft center of the outer shaft (11) can be eliminated.

Thrust bearing applying interface adsorption technology

Abstract: The invention provides a thrust bearing making use of the interfacial adsorption technology. The invention is characterized in that: the thrust bearing comprises a still flat plate and a movable flat plate, which are parallel with each other; the clearance between the still flat plate and the movable flat plate is filled with fluid lubrication oil; the mating surfaces of the still flat plate and the movable flat plate are processed to be level and smooth; partial surface of the still flat plate is provided with coating; the direction of motion of the movable flat plate relative to the still flat plate is the direction from one end of the coating of the still flat plate to the other end of the still flat plate. The relative movement of the two flat plates facilitates formation of the thrust bearing of the two flat plates; the coating is a mica powder coating modified with silane coupling agent. The bearing provided by the invention is a thrust flat plate sliding bearing having considerable carrying capacity and satisfactory antifriction and abrasion resistance. The method for achieving the invention is simple; the mating surfaces do not need to be processed into geometric shapes; the structure of the invention is simple, compact and small; and the manufacturing cost is low.

Groove configuration for a fluid dynamic bearing

Abstract: A groove configuration that improves angular stiffness in a fluid dynamic bearing is provided. A primary groove and a secondary groove are formed on a journal bearing or thrust bearing surface. The secondary groove apex induces a heightened pressure response at a localized area to counteract angular displacement. The primary groove extends a greater circumferential distance about the bearing surface as compared to the secondary groove. The secondary groove apex is also situated closer to an axial end of the journal bearing, or closer to an outer diameter of the thrust bearing, as compared to the primary groove apex. Bearing wear is prevented or minimized under gyroscopic loading. The improved angular stiffness may result in the heads of a storage device being accurately aligned with disc storage tracks. Discs may thus be designed with increased track densities, allowing for smaller discs and increased storage capacity of discs.

Detecting the onset, propagation and location of non-artificial defects in a slow rotating thrust bearing with acoustic emission

Abstract: Condition monitoring using high-frequency acoustic emission (AE) technology has remained a subject of intense study since the late 1960s. This paper demonstrates the use of AE measurements to detect, locate and monitor natural defect initiation and propagation in a conventional rolling element thrust bearing rotating at 72 r/min. To facilitate the investigation a special purpose test-rig was employed, which allowed for accelerated crack initiation on a bearing race. It is concluded that the onset of sub-surface cracks and the subsequent propagation and development to a surface spall was detectable with the AE technology. The paper also investigates the effects of attenuation and source characterisation on AE signals associated with the natural initiation and propagation of cracks on a thrust bearing race whilst in operation.

Static pressure gas bearing device

Abstract: PROBLEM TO BE SOLVED: To prevent an axis member and the flange part thereof from being not brought into contact with a bearing member even when the axis member which is rotated in high speed is whirled in an axial direction, and simplify and facilitate assembly and regulation. SOLUTION: A porous bearing member 1 is formed in a cylindrical shape, gas injecting parts 2a to 2c are arranged on the inner circumferential surface and both end surfaces, an axis member 3 is covered with each bearing member 1 from both sides of a flange part 4 arranged on the axial direction center part of the axis member 3, and the bearing member 1 is arranged on both sides of the flange part 4. The bearing member 1 is elastically supported to the inner hole 5a of a housing 5, prescribed thrust bearing clearances 7a are formed respectively between the inner side end surface of each bearing member 1 and the end surface of the flange part 4, prescribed thrust direction clearances 7b are formed respectively between the outer side end surface of each bearing member 1 and the housing 5, and gas is injected from gas injecting parts 2a to 2c of the inner circumferential surface of each bearing member 1 and both end surfaces toward the axis member 3 and the housing 5.

Thrust bearing, especially for a turbocharger

Abstract: The invention relates to an axial bearing (10) comprising at least one or more segments (18) on each of the front side (22) and the rear side (26) thereof, wherein the segments (18) on the opposite sides (22, 26) each are disposed at least partially offset from each other.

Axial flux electrical machine

Abstract: An axial flux electrical machine including a housing, a stator located within the housing, a rotatable shaft carried by the housing by means of at least a main bearing, and a rotor fixed to the shaft within the housing. Magnetic attractive forces between the rotor and the stator produce an axial thrust on the main bearing and a biasing means (preferably in the form of a spring) is arranged to urge the shaft in a direction opposite to the axial thrust so as to reduce the net load on the main bearing. This reduction in net load on the main bearing increases bearing life and improves motor efficiency.

Thrust bearings and method for cooling thrust bearings

Abstract: A thrust bearing for a turbodrill includes a first ring attached to a rotatable shaft of the turbodrill, a first plurality of bearing pads disposed on the first ring, a second ring attached to a housing of the turbodrill, and a second plurality of bearing pads disposed on the second ring and opposing the first plurality of bearing pads on the first ring. Further, the first plurality of bearing pads are in load-bearing engagement with the second plurality of bearing pads, and an orientation of the first plurality of bearing pads diverts fluid radially through the thrust bearing.

Stackable generator arrangement

Abstract: A electrical power plant with a gas turbine engine that drives two electric high speed generators connected on the two ends of the engine rotor shaft in a direct drive relation without the need for a gear box. The high speed generators can be of the same or different power rating and connected in series such that the total power output can easily be changed without the need to redesign larger high speed generators. Because the generators use permanent magnets, they can be operated as motors to drive two or more compressors. A turbine can be used to drive two or more high speed generators connected in series. Since the high speed generator/motors have thrust bearings, the thrust bearing in the turbomachine can be eliminated.

High precision grinder wheel finishing device for complex section grinding wheel processing

Abstract: The utility model relates to a high-precision grinding wheel finishing device used for machining of the complex section grinding wheel. The device is composed of a feeding mechanism, a diamond finishing wheel and a diamond finishing wheel power source, wherein the feeding mechanism adopts the an X-Y table; the diamond finishing wheel power source is an electric main shaft; the diamond finishing wheel is directly arranged on the end of an electric main shaft so as to obtain the needed high rotational speed, make the structure compact, reduce vibration and improve the finishing precision of the grinding wheel; the X-Y table is composed of a base, a lower trailing board moving in the X direction, an upper trailing board moving in the Y direction, an electric mechanism and a guiding mechanism; the electric mechanism is composed of a servo electric motor, a coupling, a ball bearing screw mandrel accessory and a bearing; the servo electric motor is directly connected with the ball bearing screw mandrel accessory through the coupling; the ball bearing screw mandrel accessory uses the flange to connect with the upper trailing board or the lower trailing board; the ball bearing screw mandrel accessory close to the side of the servo electric motor is provided with a group of precise thrust bearings arranged in pairs, in which the mode of fixed installation is adopted; and the side far from the servo electric motor is provided with a group of precise rolling bearings, in which the mode of moving installation is adopted. Thereby, the accuracy of movement of the trailing board in the X and Y directions can be improved, so that the finishing device can accurately finish various grinding wheels with complete sections.

Spindle motor and disk-shaped medium recording and reproducing device

Abstract: A spindle motor can suppress the generation of noise during swinging and the extend service life, and also suppress the increase in current consumption. The outside diameter of a thrust hydrodynamic groove is at least 10% of the outside diameter of a disk-shaped medium, and the depth of the radial hydrodynamic groove is greater than the depth of the thrust hydrodynamic groove. By adjusting to specific numbers, the angular stiffness in the thrust bearing is raised, and even if a disturbance torque should be applied, wear or noise caused by metal contact inside the bearing can be suppressed.

Actuator with built-in load sensor

Abstract: Various means for detecting the load on the bottom of a bed are proposed, but they have various problems, since the load sensor is provided separately from a bed or installed outside a bed. This invention solves the abovementioned problems by a load sensor-containing actuator in which one end side of a screw shaft 1 is rotatably supported by a base body 2; a female threaded member 3 is engaged with the screw shaft; and an actuation rod body 4 fixed to the female threaded member can advance and retreat in the axial direction of the screw shaft, wherein the base body is provided with a thrust bearing 6 coaxially with the screw shaft and an actuation cylinder 7 supporting the one end side of the screw shaft in the axial direction via the thrust bearing; a detection cylinder 9 is provided between the actuation cylinder and a support member 8 for the base body; and a strain gauge 10 is attached to the outside surface of the detection cylinder.[00011 The present invention relates to a foldable side rail for a bed or the like, particularly a foldable side rail in which multiple strut members are pivotally rotatably connected between an upper crosspiece member and a lower crosspiece member to form a parallel link mechanism.

Preliminary Analysis for an Optimized Oil-Free Rotorcraft Engine Concept

Abstract: Recent developments in gas foil bearing technology have led to numerous advanced high-speed rotating system concepts, many of which have become either commercial products or experimental test articles. Examples include Oil-Free microturbines, motors, generators and turbochargers. The driving forces for integrating gas foil bearings into these high-speed systems are the benefits promised by removing the oil lubrication system. Elimination of the oil system leads to reduced emissions, increased reliability, and decreased maintenance costs. Another benefit is reduced power plant weight. For rotorcraft applications, this would be a major advantage, as every pound removed from the propulsion system results in a payload benefit. Implementing foil gas bearings throughout a rotorcraft gas turbine engine is an important long-term goal that requires overcoming numerous technological hurdles. Adequate thrust bearing load capacity and potentially large gearbox applied radial loads are among them. However, by replacing the turbine end, or hot section, rolling element bearing with a gas foil bearing many of the above benefits can be realized. To this end, engine manufacturers are beginning to explore the possibilities of hot section gas foil bearings in propulsion engines. This paper presents a logical follow-on activity by analyzing a conceptual rotorcraft engine to determine the feasibility of a foil bearing supported core. Using a combination of rotordynamic analyses and a load capacity model, it is shown to be reasonable to consider a gas foil bearing core section.

Reducing Friction in Tilting-Pad Bearings by the Use of Enclosed Recesses

Abstract: A three-dimensional thermoelastohydrodynamic model is applied to the analysis of tilting-pad bearings with spherical pivots and equipped with deep recesses in the high-pressure regions. A potential for a 10–20% reduction in the friction loss compared to conventional plain bearing pads is documented. Design suggestions minimizing the power loss are given for various length-to-width ratios. The tilting angle in the sliding direction is more sensitive to correct positioning of the pivot point than conventional bearing pads. Improving the performance by equipping a tilting-pad bearing with a deep recess therefore requires accurate analysis and design of the bearing. Similarly, a high sensitivity perpendicular to the sliding direction suggests that this method of reducing friction is more feasible when using line pivots or spring beds than when using spherical pivots for controlling the tilting angle.