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Showing papers on "Fluid bearing published in 1990"


Patent
30 Mar 1990
TL;DR: In this paper, a spindle assembly with air bearings for use in a hard disk storage device is presented. The spindle consists of a stationary shaft assembly and a rotating hub assembly that is supported in rotation by self-acting air bearings formed between adjacent axial and radial surfaces of the shaft and the hub assembly.
Abstract: A spindle assembly with air bearings for use in a hard disk storage device. The spindle assembly consists of a stationary shaft assembly and a rotating hub assembly that is supported in rotation by self-acting air bearings formed between adjacent axial and radial surfaces of the shaft assembly and the hub assembly. The shaft assembly includes a stationary shaft. A cylindrically hollow ceramic sleeve is fitted around the shaft. A double herringbone groove pattern is indented into the outer cylindrical surface of the sleeve. A further hollow ceramic cylinder fits over the sleeve such that a suitable air bearing can develop between the outer surface of the sleeve and an inner surface defined in the cylinder. Two disk-shaped ceramic thrust plates are fitted around the shaft, one on either side of the hollow sleeve. The innermost surfaces of the thrust plates are indented with a herringbone groove pattern such that a suitable air bearing can develop between the surface of the thrust plates and the flat end surfaces of the cylinder. A motor stator assembly is fitted to the end of the stationary shaft beyond one of the thrust plates, and a magnetic rotor assembly is fitted to the inside surface of a rotating aluminum hub adjacent to the stator.

35 citations


Patent
10 Jul 1990
TL;DR: In this paper, a rotatable element is rotatably supported by hydrodynamic bearings with a lubricating fluid provided from a pressure source (26 and/or 34) with the fluid being subject to a change in state from liquid to vapor when heat from the bearings during rotation of the rotable element is absorbed by the pressurized fluid during supporting of the rotating element.
Abstract: A protection system for a rotatable element (20) which is rotatably supported by hydrodynamic bearings (22, 24) pressurized with a lubricating fluid provided from a pressure source (26 and/or 34) with the fluid being subject to a change in state from liquid to vapor when heat from the bearings during rotation of the rotatable element is absorbed by the pressurized fluid during supporting of the rotatable element in accordance with the invention includes a pressure sensor (302) in fluid communication with fluid flowing from the hydrodynamic bearings for producing a pressure signal representative of pressure of the fluid flowing from the bearings; a temperature sensor (304) in fluid communication with the fluid flowing from the hydrodynamic bearings from producing a temperature signal representative of temperature of the fluid flowing from the bearings; a prime mover (17) for driving the rotatable element with a variable rotational velocity; and a controller (400), responsive to the pressure and temperature signals, for controlling the rotational velocity of the prime mover as a function of the pressure and temperature signals to prevent the change in state of the fluid flowing from the bearings from liquid to vapor.

25 citations


Journal ArticleDOI
TL;DR: In this paper, the stability of rigid rotors supported on finite rough journal bearings using perturbation method was investigated and the effect of various surface roughness parameters on the stability was studied.
Abstract: This investigation deals with the stability of rigid rotors supported on finite rough oil journal bearings using perturbation method. The effect of various surface roughness parameters, viz., composite surface roughness, roughness orientation pattern and variance ratio on the stability has been studied. In general, surface roughness effect when incorporated into the analysis does not show a significant change in the stability for surfaces having same roughness structure. However, the effect of variance ratio (i.e., surfaces having different roughness structure) on stability is quite marked

19 citations


Journal ArticleDOI
TL;DR: In this paper, the authors measured the PEHL film thickness in a large instrument ball bearing by electrical capacitance across its ball set and found a correlation between changes in film thickness and changes in Basic Speed Ratio (BSR) measured at the same time.
Abstract: Parched Elasto Hydrodynamic Lubricant (PEHL) film thickness in a large instrument ball bearing is measured by electrical capacitance across its ball set. Correlation is shown between changes in film thickness and changes in Basic Speed Ratio (BSR) measured at the same time. BSR is confirmed as a sensitive, non-intrusive measure of transients in film thickness in a real bearing.

13 citations


Patent
05 Jan 1990
TL;DR: In this paper, a hydraulic ram is supported by a hydrostatic bearing assembly mounted on a main frame, which is formed with a unique arrangement of hydrostatic pressure pad slots and hydrodynamic stepped end sections.
Abstract: The ram is supported through a hydrostatic type bearing support assembly mounted on a main frame. The support bearings are formed with a unique arrangement of hydrostatic pressure pad slots and hydrodynamic stepped end sections to center the ram with constantly pressurized and flowing oil films supplied through the pressure pad slots. The hydrodynamic bearing sections provide hydrodynamic support at high reciprocating speeds and the pressure pad slots provide hydrostatic support at lower reciprocating speeds that occur at the end of the working and return strokes of the ram. A piston and cylinder arrangement mounted to the bearing housing imparts a deflection force against the ram, between the end bearings and through a center bearing, to counteract gravitational vertical deflection of the unsupported working end of the ram. A cardan type crank drive mechanism for converting rotational input force into straight line reciprocating movement of an output shaft is also disclosed.

12 citations


Journal ArticleDOI
TL;DR: In this article, the vibration of a translating string, controlled through hydrodynamic bearing forces, is analyzed by the transfer function method, and an integral formulation of the controlled system response is proposed that leads to the closed-loop transfer function.
Abstract: The vibration of a translating string, controlled through hydrodynamic bearing forces, is analyzed by the transfer function method. Interactions between the string response and the bearing film are described by the bearing impedance function. This function depends on the string translation speed, the frequency of the film thickness variation, and the spatial location of the bearings. The control system consists of the translating string, bearings, actuators and sensors, and feedback elements. An integral formulation of the controlled system response is proposed that leads to the closed-loop transfer function. The frequency response of the control system is studied in the system parameter space. The feasibility of adding active control to improve the bearing force control is also considered.

8 citations


Journal ArticleDOI
TL;DR: In this paper, the authors presented a mathematical model of the flow and pressure developed in a hydrodynamic guide bearing film under transverse vibration of a translating band, and derived the perturbed pressure in the frequency domain based on a linearized, incompressible fluid film model.
Abstract: This paper presents a mathematical model of the flow and pressure developed in a hydrodynamic guide bearing film under transverse vibration of a translating band. The perturbed pressure is derived in the frequency domain based on a linearized, incompressible fluid film model. Unsteady fluid inertia is included in the model. The perturbed pressure is generated by two mechanisms, one caused by the band convection, and the other by the band transverse vibration. Results for both the transient and steady state responses of the film are presented and discussed

8 citations


Journal ArticleDOI
TL;DR: In this article, the influence of lubrication conditions on the performance characteristics of sector-shaped pad thrust bearings, which are subjected to the effects of both turbulence and fluid film inertia, is investigated theoretically and experimentally.
Abstract: An influence of lubrication conditions on the performance characteristics of sector- shaped pad thrust bearings, which are subjected to the effects of both turbulence and fluid film inertia, is investigated theoretically and experimentally. The momentum equations in terms of pressure and stream function are solved by applying a numerical calculation technique combining control volume integration and the Newton-Raphson linearization method, under three kinds of inlet boundary conditions in relation to three types of lubrication conditions, namely: the flooded condition, the overflooded condition, and the starved condition

6 citations


Patent
18 Jan 1990
TL;DR: In a linear guide for precision machines, the linear bearing of the mobile bearing element which moves relative to the stationary bearing element is achieved by means of magnetic bearings (3, 5) or air bearings (9, 11).
Abstract: In a linear guide for precision machines, the linear bearing of the mobile bearing element (2) which moves relative to the stationary bearing element (1) is achieved by means of magnetic bearings (3, 5) or air bearings (9, 11). The drive is provided by electric motors, in particular linear motors (6, 7). To ensure optimal stability to temperature fluctuations and hence optimal precision, for example in measuring machines, all heat-generating electrical devices, i.e. the coils (8) of the magnets (3) or motors (6) are manufactured by superconducting technology.

4 citations


Journal ArticleDOI
TL;DR: In this article, the effects of turbulence and fluid film inertia on the stability of high-speed, elliptical journal bearings were theoretically investigated, and the relationship between the stability and the ellipticity ratio of elliptical bearings in the turbulent inertial flow regime were discussed.
Abstract: The effects of turbulence and fluid film inertia on the stability of high-speed, elliptical journal bearings were theoretically investigated. Based on the linearized analysis, the dynamic fluid film coefficients such as spring, damping and acceleration coefficients, considering the combined effects of turbulence and fluid film inertia, were obtained for various values of ellipticity ratio. Moreover, by applying the Routh-Hurwitz stability criterion to the equation of motion for the rigid rotor supported by two identical aligned elliptical bearings, we estimated the whirl onset speeds. From the numerical results, the relationships between the stability and the ellipticity ratio of elliptical bearings in the turbulent inertial flow regime were discussed.

4 citations


Journal ArticleDOI
Abstract: Surface roughness effects on the hydrodynamic lubrication characteristics of finite length gas journal bearings has been studied by numerically solving the ensemble averaged compressible Reynolds equation. Analysis is based on the premise that the ensemble averaged Reynolds equation with film thickness averages using incompressible lubrication assumptions is valid for compressible lubrication at moderate compressibility numbers (Λ≤100). Film thickness averages are derived for a roughness distribution given by a polynomial fit of a Gaussian distribution. Load capacities and viscous friction losses for finite length gas journal bearings with longitudinal and transverse roughness patterns are compared with smooth bearings for varying eccentricity ratios, LID ratios and compressibility numbers. The finite length time dependent Reynolds equation for rough bearings is solved using a semi-implicit scheme and compared with smooth bearing results. As an illustration, the nonlinear transient unbalance response of a...

Patent
16 Apr 1990
TL;DR: In this article, a dynamic pressure fluid bearing device of high performance was obtained by tightly closing up a gas pressurized higher than atmospheric pressure in a housing, in spite of use of a compressible fluid gas.
Abstract: PURPOSE:To obtain a dynamic pressure fluid bearing device of high performance by tightly closing up a gas pressurized higher than atmospheric pressure in a housing. CONSTITUTION:Pipes 24, 25 provided with valves 22, 23 are respectively arranged on the upper and lower part of a side wall in the housing 21 of a dynamic pressure gas radial bearing device 19. Further, an O-ring 26 is fitted on the inside of the lower edge connecting part to form a pressure tight structure. For example in this case, pressurized air 18 at three atmosphere is closed up in this housing 21. In this way, by closing up a gas pressurized higher than atmospheric pressure in the housing 21 having closed structure, compressibility constant indicating degree of influence on the performance of the dynamic pressure fluid bearing device 19 becomes small in inverse proportion to high pressure of the gas, and the dynamic pressure fluid bearing device of high performance can be obtained, in spite of use of a compressible fluid gas.

Journal ArticleDOI
TL;DR: In this article, the relationship between the variation of pressure distribution and the stability of elliptical journal bearings in a turbulent inertial flow regime was examined theoretically based on the nonlinear analysis for three different values of ellipticity ratio of m=0, 0.5 and 1.0.
Abstract: In this second paper, the relationship between the variation of pressure distribution and the stability of elliptical journal bearings in a turbulent inertial flow regime it examined theoretically based on the nonlinear analysis for three different values of ellipticity ratio of m=0, 0.5 and 1.0. The nonlinear equation of motion for the rigid shaft supported on the two identical aligned elliptical bearings was solved by the improved Euler's method and the relation between the pressure distribution and the transient motion of the journal center was presented in the graphic form. From the numerical results, the effects of ellipticity ratio, turbulence and fluid film inertia on the dynamic behavior of elliptical journal bearings are clarified, and the relationship between the variation of pressure distribution and the stability is discussed.

Patent
31 Oct 1990
TL;DR: In this paper, radial bearings are fitted to the upper and lower openings of a bearing supporting body and a minute clearance is formed between a bearing between a magnetic seal and a thrust bearing and a shaft, which is filled with magnetic fluid.
Abstract: PURPOSE:To improve uneven rotation and the tilting of the surface of a mirror by a method wherein radial bearings are fitted to the upper and lower openings of a bearing supporting body and a minute clearance, formed of a bearing supporting part between a magnetic seal and a thrust bearing and a shaft, is filled with magnetic fluid CONSTITUTION:An air pocket 9 is formed at the upper end of a bearing supporting part 71 and a magnetic seal 10 is fitted into the inner periphery of the air pocket 9 The magnetic seal 10 is constituted of a permanent magnet and the yoke of a magnetic body, which pinches the permanent magnet, and a minute gap is provided between the inner periphery of the magnetic yoke and a shaft 15 to effect magnetic seal by the minute gap In this case, radial bearings 4, 5 or a thrust bearing 6 and a space between the bearing supporting part 71 and the shaft 15 become a sealed type magnetic fluid bearing 18 by filling the gap between the bearing supporting part 71 of the bearing supporting body 7 and the shaft 15 with the magnetic fluid 11 According to this method, uneven rotation of a motor or the tilting of the surface of a polygon mirror 14 may be improved

Patent
21 Aug 1990
TL;DR: In this article, the authors proposed a method to shut off vibration by installing a number of air bearings under the borne part of a building, sending high compressed air to these air bearings from a compressor in the event of an earthquake, and putting the bearing part afloat in the air.
Abstract: PURPOSE:To shut off vibration by installing a number of air bearings under the borne part of a building, sending high compressed air to these air bearings from a compressor in the event of an earthquake, and putting the borne part afloat in the air. CONSTITUTION:A groove 4 is formed in the undersurface of a foundation slab 3 of building mass 2, and air bearings 6 installed on a plate 5 are slipped into this groove 4. These bearings 6 are connected with a compressor 12 through a flexible hose 11, and output from a seismic sensing device is introduced to a computer, and a valve 13 is controlled. When an earthquake has occurred, the valve 13 is opened with the output from sensing, and the air in an air receiver 14 is released, and air is jetted out of the bearings 6, and by this pressure the whole mass 2 is put afloat from the foundation 1. Thus vibration is shut, and flame damage, etc., of building can be prevented.

Journal ArticleDOI
TL;DR: In this paper, a hydrodynamic bearing whose oil film dynamic stiffness and damping coefficients could be tuned to take on low values, without upsetting the bearing steady load carrying capacity, in order to obtain an improved dynamic response for machines running in such bearings.

Patent
10 Jul 1990
TL;DR: In this paper, the authors proposed a method to prevent a bearing from being damaged in the course of recording and reproduction by incorporating a device for detecting a service life of a fluid bearing.
Abstract: PURPOSE:To prevent a bearing from being damaged in the course of recording and reproduction by incorporating a device for detecting a service life of a fluid bearing CONSTITUTION:When a radial bearing 9 is rotated, a thrust bearing 4 floats up a little, and also, the radial bearing 9 and the center axis 3 hold an appropriate gap, the axis 3 and the bearing 4 do not come into contact directly to each other and a fixed cylinder 5 is rotated A head 6 attached to the cylinder 5 also rotates and information is recorded and reproduced to and from a magnetic tape When a voltage is applied between a brush 12 and the center axis 3 is such a normal state and a contact resistance is measured, it becomes large However, when a bearing 11 reaches its service life or evaporates and its quantity decreases, pressure of bearing grease 11 of a thrust bearing part and a radial bearing part is eliminated and the bearing 4 and the bearing 9 come into contact with the axis 3 In such a way, by detecting a fact that an electric resistance becomes small and outputting an electric signal, a recording/ reproducing device is stopped and an alarm is issued to the outside

Patent
25 Jan 1990
TL;DR: In this article, the linear bearing of the mobile bearing element which moves relative to the stationary bearing element is achieved by means of magnetic bearings (3, 5) or air bearings (9, 11).
Abstract: not available for EP0387312Abstract of corresponding document: DE3823978In a linear guide for precision machines, the linear bearing of the mobile bearing element (2) which moves relative to the stationary bearing element (1) is achieved by means of magnetic bearings (3, 5) or air bearings (9, 11). The drive is provided by electric motors, in particular linear motors (6, 7). To ensure optimal stability to temperature fluctuations and hence optimal precision, for example in measuring machines, all heat-generating electrical devices, i.e. the coils (8) of the magnets (3) or motors (6) are manufactured by superconducting technology.

Journal ArticleDOI
TL;DR: In this paper, the hydrodynamic characteristics of a cylinder-plane bearing in normal motion were investigated by using the Reynolds equation in conjunction with the Coyne-Elrod rupture model.
Abstract: The hydrodynamic characteristics of a cylinder-plane bearing in normal motion is investigated by using the Reynolds equation in conjunction with the Coyne-Elrod rupture model. It is seen that the solutions of the pressure distribution as well as the rupture point are more acceptable than those found using the Reynolds boundary conditions. It is found that the squeeze effect cancels the entraining effect as the approach velocity is large

Patent
24 Jan 1990
TL;DR: In this article, a liquid regulating hole connected to the bottom of the cylindrical hole of a bearing from the exterior is used to prevent wear of a radial bearing surface due to the shortage of oil.
Abstract: PURPOSE:To prevent wear of a radial bearing surface due to the shortage of oil by providing a liquid regulating hole connected to the bottom of the cylindrical hole of a bearing from the exterior, inserting a shaft into the bearing and fitting a plug into the liquid regulating hole CONSTITUTION:An oil regulating hole 5 connected to the exterior from the corner of a thrust bearing surface 26 and a radial bearing surface 2a is provided at a bearing 2 for mounting a shaft 1 A plug 6 is inserted in the oil regulating hole 5 The plug 6 releases air between air between the shaft 1 and the bearing 2 from the oil regulating hole 5 and also the oil quantity between the shaft 1 and the bearing 2 is regulated Thus, wear of the radial bearing surface due to the shortage of the oil can be prevented


Patent
01 Nov 1990
TL;DR: In this paper, a fluid bearing damper for damping radial motion of a bearing is described, which includes a plurality of concentric, circular, thin shims located in an annular damping chamber to present thin, radially stacked damping cavities.
Abstract: A fluid bearing damper (32) for damping radial motion of a bearing (16) includes a plurality of concentric, circular, thin shims (34, 36) located in an annular damping chamber (22) to present thin, radially stacked damping cavities (46). A portion (36) of the shims have protruding radial lands (42, 44) that partially define the cavities (46), carry radial loads through the damper (32) and produce a controlled mechanical centering force as well as serving to ensure replenishment of fluid film cavities (46).