Showing papers on "Thrust bearing published in 1996"

Hydraulic turbine power generator incorporating axial thrust equalization means

Abstract: A sealless turbine generator mounted on a single shaft compising a radial turbine having a unique thrust equalizing mechanism mounted thereto and operative with a portion of the applied hydraulic fluid to the turbine radial runner and a thrust bearing for equalizing the generated thrust forces by providing a small axial, bidirectional movement of the thrust bearing and the elements mounted on the single shaft and an induction generator driven by the turbine. The shaft along with the induction generator and the turbine components except the turbine runner are isolated in a common housing and the entire assembly included in a submersible containment vessel having a fluid inlet and outlet for receiving the input hydraulic fluid flow at a preselected fluid pressure and velocity for controlling the speed of the turbine. The induction generator includes a variable frequency, exciting current source for the generator stator windings that permits changing the synchronous speed of the generator as required by the hydraulic fluid flow and hydraulic fluid head to permit the overall efficiency of the turbine generator to be optimized. The turbine generator is operative with liquified gases that may be utilized to lubricate and cool the thrust bearing and the induction generator by the small portion of the operative fluid utilized for operating the thrust equalizing mechanism.

Implant module unit and rotating seal for prosthetic joint

Abstract: An implantable module for use with a prosthetic joint that utilizes a bellows and a rotating seal for encapsulating the articulating members of the implant. This invention is comprised of flexible metallic bellows which serve the same function as the presently used boot, which includes containing a lubricant to decrease the wear to the articulating surfaces and preventing the lubricant or wear debris from escaping into the surrounding tissues. The implant module has the novel feature of maintaining the articulating bearing surfaces in proper alignment by utilizing a spring force from the metallic bellows to augment the function of the tendons, ligaments, and muscles that have been surgically traumatized and to prevent exposure of the articulating surfaces to excessive expansion, compression, or rotational forces. Furthermore, a thrust bearing with rotating seal is located between the flexible bellows and the neck of the implant freeing the bellows from rotational cycles, thus increasing the life of the bellows. The thrust bearing transfers the spring force from the metallic bellows to the permanent implant and prevents axial movement of the rotating seal along the neck. The thrust bearing with rotating seal can also be used to enhance the performance and longevity of non-metallic flexible members. The implant module includes the metallic bellows, the thrust bearing with rotating seal and the enclosed lubricated articulating assembly. If necessary, the implant module may be surgically removed and replaced by a new implant module without disturbing the integrity of other implantable components that are affixed to bone.

Active inherent restrictor for air-bearing spindles

Abstract: An active control method for aerostatic bearings is proposed in this paper. The proposed method employs an active inherent restrictor AIR, (which was invented by the authors) to control pneumatic pressure on the bearing surface. The AIR consists of a piezoelectric actuator with a through hole, one end of which is small enough to function as an orifice when the actuator is embedded in the bearing to be controlled. Nine AIRS are incorporated into the aerostatic radial and thrust bearings of an air bearing spindle. According to the radial and/or thrust displacements of the spindle detected by sensors, a microcomputer changes the length of the piezoelectric actuators for controlling the orifice area of the AIRs and for compensating the displacements. Thus, the stiffness and the rotational accuracy in both radial and thrust directions can be improved without the occurrence of pneumatic hammer. Instead of ordinary passive inherent restrictors, the AIR can be incorporated into most conventional aerostatic bearings. An example of retrofit of the AIR to a commercially available air bearing spindle is also shown.

Axial flow pump/marine propeller

Abstract: An axial flow pump/marine propeller (10; 100; 200; 300; 400) has a pump body carrying a stator (20; 120; 220; 320; 420) which defines a cylindrical inner space, a rotor member (40; 140; 260; 360; 460) being rotatably located in the inner space, and electromagnetic means (24, 26, 44; 124, 126, 144) arranged between the stator and the rotor for generating a rotational magnetic field to drive the rotor to rotate. The rotor has a hollow structure with one or more propelling blades (48; 148; 283; 366) for driving the fluid to flow along the central axis of the pump. This arrangement provides a driving force which produces minimum fluid disturbance and drag therefore a high energy efficiency. The rotor is supported in the pump body by a suspension bearing mechanism which provide rotational and thrust bearing in response to the rotor's rotational and/or axial movements to retain the rotor at a balanced position. In the disclosed embodiments, the bearing means can be formed by mechanical (50; 380; 480), magnetic (150; 190; 240; 250) or hydraulic (49; 149; 270; 356) mechanisms, or a combination of any of them, which keep the rotor fully suspended in and coaxially aligned with the pump body during its operation while at the same time reduce the friction and wear of the rotating parts. By using the magnetic and/or hydraulic suspension to support the rotor, it also avoids the problems and costs of having sealing and lubricating arrangements for the rotary parts, therefore reduce both the manufacturing and maintenance costs. Further arrangements (160, 166) are incorporated into the structure to automatically adjust the axial position of the rotor when it is fully suspended by the hydraulic and/or magnetic mechanisms. Compressible spiral blades can be used to cope with frequent changes of electric inputs and/or output loads. Some of the disclosed embodiments provide clog-free structures suitable for a wide range of applications, such as sewerage pump, sludge pump or marine propeller. An arrangement of two anti-spiral driving members (366, 370; 466, 470) are disclosed for high pressure applications.

Method for providing lubricant to thrust bearing

Abstract: An apparatus for providing lubricant to thrust bearings and rotors of a rotary screw compressor. The apparatus includes a temperature sensor for sensing the temperature of the lubricant supplied to the rotors; a pressure sensor for measuring the pressure of the compressed gas discharged from the compressor; and a speed sensor for detecting the operating speed of the rotors. An electronic controller responsive to signals received from the temperature sensing means, the pressure sensing means and the speed sensing selectively opens and closes the second valve means to optimize the volume of lubricant supplied to the compressor rotors, and also controls the first valve to control the flow of lubricant to the thrust bearings. A pressure regulator controls the supply of lubricant to the thrust bearings in response to input signals received from the electronic controller. The regulator is flow connected to each thrust bearing by an independent lubricant supply line to thereby permit the pressure of one thrust bearing to be adjusted independent of the other thrust bearing.

Turbine engine having improved thrust bearing load control

Abstract: A modified turbine engine design in which control of the forward load on a thrust bearing is improved, while reducing or eliminating the need for the use of a balance piston is disclosed. The turbine engine has a longitudinal axis and comprises, a compressor for pressurizing gases in the engine. The impeller has an impeller rear face and a tip. The engine further comprises a shaft mounted to a thrust bearing for rotation about the axis. The impeller is fixed to the shaft for rotation therewith. A cavity fixed within the engine casing is defined at least by the impeller rear face and is in communication with the pressurized gases at the impeller tip. The engine further comprises a bleed in communication with both the cavity and the pressurized gases, so that the cavity is pressurized by the pressurized gases from the impeller tip and the bleed, thereby loading the impeller rear face to load the thrust bearing through the shaft. Preferably, the pressurized gases from the bleed reduce flow swirl in the cavity and thereby increase the pressure in the cavity.

Grooved hydrodynamic bearing arrangement including a porous lubricant reservoir

Abstract: The hydrodynamic bearing arrangement comprises a journal sleeve defining a journal bore and a journal thrust surface. A shaft is mounted in the journal bore by means of a hydrodynamic journal bearing which permits rotation of the shaft and the journal sleeve relative to one another. A thrust plate extends transversely from the shaft and defines two hydrodynamic thrust bearings in combination with the journal thrust surface and a counterplate which is mounted adjacent to the thrust plate. A porous lubricant reservoir is mounted adjacent to the thrust plate. The porous lubricant reservoir serves to remove wear particles from the lubricant in the bearing arrangement, and provides a supply of lubricant to the hydrodynamic journal and thrust bearings should they become depleted of lubricant.

Grooved hydrodynamic thrust bearing

Abstract: Two thrust bearing surfaces are separated by bearing fluid and are rotatable relative to one another. One of the bearing surfaces defines a plurality of continuous lands extending from an inner to an outer radius of the bearing surface. Adjacent lands define between them a continuous groove which has an undivided portion in an inner annulus and a divided portion in an outer annulus of the bearing surface. The continuous groove is divided in the divided portion by an intermediate land located between the adjacent continuous lands. The divided portion of the continuous groove communicates in unbroken fashion with the divided portion.

Semiconductor wafer polishing machine and method

Abstract: A semiconductor wafer polishing machine and method are described in which a motor driven rotating spindle is coupled to the wafer carrier by a flexible coupling element. The carrier is releasably attached to a load transfer plate by a vacuum pressure chamber to enable removal of the carrier for loading and unloading of wafers prior to and after polishing. The motor and spindle together with the load transfer plate and carrier are moved between and raised rest position and a lowered polish position by a positioning cylinder. A load pressure bellows applies a polishing load force to the load transfer plate through an air lubricated thrust bearing to urge the wafers on the carrier against a rotating polishing table for polishing the wafers. The air bearing isolates the load force of the bellows from the rotational force of the spindle and allows sliding movement of the load plate relative to the bellows. The carrier, load transfer plate and the polishing table may all be made of rigid foam material, such as metal or ceramic, in order to reduce the mass and weight of these elements while providing them with a strong rigid construction.

F117-PW-100 hybrid ball bearing ceramic technology insertion

Abstract: Results of an Advanced Research Projects Agency (ARPA) sponsored project to demonstrate the operational benefits of incorporating advanced structural ceramic ball elements into the F117-PW-100 aircraft gas turbine engine high rotor thrust bearings is described. This program consists of design, fabrication, and experimental evaluation of candidate hybrid ball bearing designs in Pratt & Whitney and MRC Bearings test facilities. The bearing design criteria and development test conditions utilized for the project are compatible with the requirements of the F117-PW-100 engine system application. Two hybrid bearing designs were produced by analytically varying internal geometry features such as M-50 race curvatures and contact angles to optimize for the modulus of elasticity of the ceramic balls. CERBEC grade NBD 200 silicon nitride ceramic balls (1 1/8 in. size) demonstrated integrity and a quadruple rolling contact fatigue life improvement versus state-of-the-art M-50 steel balls in single ball test rigs. Thermal performance data obtained in full-scale bearing rig performance testing with 178 mm size hybrid and all-steel baseline bearings shows comparable characteristics. The hybrid bearing displayed a distinct survivability benefit in bearing liquid lubricant starvation testing. Two dozen hybrid bearings will be fabricated for full-scale bearing rig endurance tests to be conducted in 1995-1996 as a prerequisite to validation in operating F117-PW-100 engines in 1996-1997.

Thrust load compensating system for a compliant foil hydrodynamic fluid film thrust bearing

Abstract: A thrust load compensating system for a compliant foil hydrodynamic fluid film thrust bearing is disclosed. The system includes an end cap over the free end of a rotary machine shaft, a compliant foil hydrodynamic fluid film journal bearing located at the free end of the shaft, and a source of air whose pressure varies with the square of turbomachine speed. The compliant foil hydrodynamic fluid film journal bearing located at the free end of the shaft serves as a non-contacting rotary shaft seal and, together with the end cap and free end of the shaft forms a thrust piston chamber. The thrust load compensating system of the present invention can be utilized in high speed rotary machines that have a compressor wheel and a turbine wheel that generate large axial aerodynamic forces that increase with speed.

Thermoelastohydrodynamic Analysis of Fixed Geometry Thrust Bearings Including Runner Deformation

Abstract: A thermoelastohydrodynamic theory for the analysis of sector thrust bearings is presented. The analysis includes the generalized Reynolds equation and a fully elliptic three-dimensional energy equation in the film. In addition, full three-dimensional heat transfer is allowed in the pad while axisymmetric conduction is allowed in the runner. Three-dimensional elastic deformation due to mechanical and thermal loading is allowed in the pad while axisymmetric mechanical elasticity is allowed in the runner. The performance of a parallel tapered-land thrust bearing including runner deformation effects is analyzed as a function of different models. It is seen that mechanical deformation of the pad affects the operating characteristics only slightly while thermal deformation of the pad can cause large increases in operating temperature. The runner deformation effects can include a reduction of the maximum film temperature at slight deformation or a large increase in film temperature at the inner radius of the pad...

Bearing device and spindle motor provided with the bearing device

Abstract: A bearing device where a sliding bearing rotatably supporting a shaft is molded with an inexpensive sintered material, three asymmetrical circular arc-shaped radial bearings are formed in the inner peripheral surface of the shaft, taper land-shaped thrust bearings are formed in the opposite end surfaces of the radial bearing surface, T-shaped bubble removing means which is constituted by axial and radial flow passages formed in the shaft opposed to the radial bearing is provided, and magnetic fluid is used as a lubricant A magnetic disk unit using the bearing device is also disclosed

Design of a Magnetic Bearing-Supported Prototype Centrifugal Artificial Heart Pump

Abstract: Magnetically supported ventricular assist devices are beginning to be developed. This paper describes a continuous flow centrifugal flow prototype pump that has been constructed and successfully tested. It has four active electromagnetic bearings—two radial and two thrust bearings. The total capacity, current gains and stiffness of the bearings are described. Bearing coil currents were measured with the pump rotor in various orientations to approximately determine the actuator current gains. These parameters were then employed to estimate the radial and thrust forces exerted on the pump rotor during static operation in air and water and then with the pump rotating in both air and water. Performance properties—differential pressure and efficiency-were measured and found to be in the range necessary for adult human cardiac requirements. Presented as a Society of Tribologists and Lubricant Engineers paper at the STLE/ASME Tribology Conference in Kissimmee, Florida, October 8–11, 1995

Thrust bearing assembly

Abstract: A thrust bearing assembly for a submersible motor assembly of a submersible pump assembly comprising first and second bearing members or plates and first and second bearing holders contained within a housing. Each bearing plate is in the form of a disk having a bearing surface, and the first and second bearing plates are disposed between the first and second bearing holders with the bearing surfaces in face-to-face contact. The first bearing holder is in the form of a thrust bearing holder, and the second bearing holder is in the form of a gimbal plate. The first bearing plate is adapted to rotate with a rotor shaft of the submersible pump assembly and to impose a thrust load on the second plate, and the second bearing plate is adapted to remain stationary relative to the rotating first bearing plate. Grooves are defined by one or both of the bearing surfaces to allow fluid from a fluid supply to enter between the bearing surfaces to create a fluid film to lubricate and cool the bearing surfaces.

Axial Load Capacity of Water-Lubricated Hydrostatic Conical Bearings With Spiral Grooves (On the Case of Rigid Surface Bearings)

Abstract: This paper describes the static characteristics of water-lubricated hydrostatic conical bearings with spiral grooves. Hydrostatic conical bearings treated here have been designed for high speed spindles and are intended to apply to spindles for drilling small holes of printed circuit-boards. Pressurized water is first fed to the inside of the rotating shaft and supplied to spiral grooves on the shaft surface through feeding holes. Therefore, water pressure is greatly increased at outlets of feeding holes due to the centrifugal force by shaft rotation. Furthermore, water pressure is also increased by the viscous pump effect of spiral grooves. Water pressures in the bearings under concentric condition are numerically obtained by using the finite element method and calculated results are compared with experimental ones. It is consequently found that this water-lubricated hydrostatic conical bearings with spiral grooves are very suitable for precision high speed spindles.

Wet type sliding apparatus comprising thrust bearing

Abstract: A wet type sliding apparatus comprising a thrust bearing which operates in the presence of a lubricating liquid, wherein the thrust bearing has a sliding surface composed of a resin composition comprising a carbon fiber, a fluorocarbon polymer and a thermoplastic resin other than fluorocarbon polymer, the carbon fiber content being 10 to 45% by weight based on the weight of the composition and the fluorocarbon polymer content being 0.1 to 8.5% by weight based on the weight of the composition, the thrust bearing in said wet type sliding apparatus being excellent in wear resistance, mechanical strength and friction coefficient at the time of starting even under a high load.

System for balancing loads on a thrust bearing of a gas turbine engine rotor and process for calibrating control therefor

Abstract: A process for periodically calibrating an algorithm in a control unit of a system for balancing loads on a thrust bearing of a gas turbine engine rotor is disclosed involving the steps of initializing a calibration of the control unit algorithm, causing the engine to attain a crossover condition, measuring the residual load on the rotor thrust bearing, calculating a residual load on the rotor thrust bearing by means of the control unit algorithm, comparing the measured residual load and the calculated residual load on the rotor thrust bearing to determine a difference therebetween, and modifying the control unit algorithm to compensate for the difference between the measured and calculated residual loads on the rotor thrust bearing.

System and method of controlling thrust forces on a thrust bearing in a rotating structure of a gas turbine engine

Abstract: A system for controlling thrust forces on a thrust bearing in a rotating structure of a gas turbine engine at designated operating points including a device for providing thrust load compensation to the thrust bearing, a control for operating the thrust load compensation device, and a sensor for detecting rotational cage speed of the thrust bearing. The sensor provides a signal to the control when the rotational cage speed of the thrust bearing drops below a specified ratio of the rotational speed for the rotating structure, the signal being indicative of an incipient skid condition for the thrust bearing. The control then causes the thrust load compensation device to provide an additional predetermined load on the thrust bearing when it receives the signal from the sensor so that a resultant load thereon is within a specified load range which extends the life of the thrust bearing.

Hydrodynamic bearing assembly with single sided grooved counterplate

Abstract: A spindle motor includes a rotating hub for supporting one or more discs in a disc drive, and a hydrodynamic bearing system for supporting a hub for rotation, the bearing system includes a sleeve and a shaft fitted into an axial bore of the sleeve. The shaft and the sleeve rotate freely relative to one another, and together, define a journal bearing. The shaft supports an annular thrust plate. The thrust plate extends into a recess formed by an axial face stepped into the sleeve and a counterplate parallel to the axial face and the thrust plate and attached to the sleeve. A first surface of the thrust plate faces the axial face of the sleeve which has a groove pattern formed on it. A surface of the counterplate faces an opposed, second surface of the thrust plate which has a groove pattern formed on it, to form an effective fluid pumping system in the hydrodynamic bearing.

A Rolling Element Tribometer for the Study of Liquid Lubricants in Vacuum

Abstract: A tribometer for the evaluation of liquid lubricants in vacuum is described. This tribometer is essentially a thrust bearing with three balls and flat races having contact stresses and ball motions similar to those in an angular contact ball bearing operating in the boundary lubrication regime. The friction coefficient, lubrication lifetime, and species evolved from the liquid lubricant by tribodegradation can be determined. A complete analysis of the contact stresses and energy dissipation together with experimental evidence supporting the analysis are presented.

Acoustic catheter with reduced friction drive

Abstract: An acoustic catheter (10) has a shaft (18) driven by a rotary motor (60). The shaft drives a rotary-to-axial motion converter (30) near the distal end (14) of the catheter. The converter (30) includes a rotary driver (42) with a wavy or sinusoidal bearing surface (36) facing a similarly wavy face (38) of a follower element (44). As the rotary driver (42) rotates, the follower (44) moves axially with a reciprocating motion. High rotational speeds are required to achieve high acoustic frequencies. The high speeds and high acceleration rate of the follower result in frictional forces which cause undesired heating. The heating effects are reduced by a magnetic bearing arrangement associated with the mating bearing surfaces of the rotary driver and follower, which tends to keep them slightly separated, and thereby reduce friction. Other embodiments use magnets to restore the follower to its proximal position following each excursion, and use magnetic thrust bearings for the rotary driver.

Spindle motors with hard coated hydrodynamic bearings

Abstract: A spindle motor having hydrodynamic bearings formed between a hardcoated shaft with a radial thrust bearing plate substantially perpendicular to the axis of the shaft, a hard coated sleeve, and a hardcoated thrust ring. An axial bearing cavity is formed between the sleeve and the shaft. A first radial bearing cavity is formed between a radial surface of the sleeve and a lower radial plate surface. A second radial bearing cavity is formed between a lower surface of the thrust ring and an upper radial plate surface. Lubricant at least partially fills the cavities to form hydrodynamic bearings therein. The surface hard coats are preferably ceramic-like coatings such as titanium nitride, boron carbide, or Laser Cut 964. A method for fabricating a motor having hydrodynamic bearings includes the steps of machining motor components from a metal such as steel or bronze, coating the components with a surface hard coat, and assembling the motor.

High pressure water pump system

Abstract: A high pressure water pump system, including a motor (20), an intermediate flange (30) and an axial drive water pump (60) wherein the intermediate flange unites the motor and the high pressure water pump. A wobble disk assembly (62) is attached to an end of the drive shaft of the motor and located in a second recess (36) of the intermediate flange. The intermediate flange (30) is shaped to receive the wobble disk assembly (62). Thrust bearings, consisting of thrust washers (41) and cylindrical or spherical rollers (42), are located in a first recess (34) of the intermediate flange (30) and act on a part of the wobble disk assembly. A bushing (43) made of sintered ferrous material or of plastic material is press-fitted between the first recess (34) and the back part (63) of the wobble disk assembly (62). A plug (45) is applied to the end of the drive shaft (22).

Thrust bearing arrangement

Abstract: A hydrodynamic thrust bearing arrangement (10) (Fig 1) for supporting a rotating machine shaft (12) against axial thrust forces comprises a collar (22) carried by the shaft with axially spaced, axially facing faces (24, 26), one of which, say (24), bears against an array of bearing pads (34L) by way of an intervening lubricant film. The bearing pads may be faced with a polymer or other material which as a poor conductor of heat from the lubricant film which may permit the lubricant to overheat and the film to break down. To avoid this, the collar is made from a metal having a thermal conductivity greater than 150 W m-1 ok-1 and with such collar thickness to withstand the bending stresses of the axial thrust forces, and the un-loaded face (26) is in contact with a coolant, typically the lubricant, which can transfer heat from the hydrodynamic film even when at ambient temperature. Copper or aluminium alloys may be used, and although require greater thickness than the traditional steel collar for the same lending stiffness, more than compensate by the simplicity of transferring heat out of the collar.

Composite journal and thrust bearing system

Abstract: A composite journal and thrust bearing system having a bearing housing with a journal and a thrust face lined with a high performance polymer, such as a polyimide, that is useful in applications requiring loss of lubrication protection.

Downhole tool bearing assembly

Abstract: A downhole tool bearing assembly is provided which utilizes a secondary annular threaded locknut and a compression ring in order to take up tolerance stack-up and to provide supplemental preload through a bearing housing assembly, thus helping to ensure against accidental disassembly during operation. The bearing housing assembly is comprised of a prepackaged subassembly of thrust bearings, sleeves and, optionally, "BELLEVILLE"-type disk springs which can be quickly and easily installed onto a downhole tool drive shaft or other similar apparatus by maintenance personnel having a minimum of training. The bearing housing assembly is designed such that reconfiguration involves little more than removal and reinstallation in the opposite orientation, thereby overcoming the need to reconfigure the bearing assembly one bearing at a time.