DETAILED DESCRIPTION OF THE INVENTION The invention is an automatic means for adjusting the parameters of an axially unstable magnetic bearing such that its force balance is maintained near the point of metastable equilibrium, at which point complete stabilization can be obtained with the application of only weak restoring forces, either from a mechanical bearing (running at near-zero load, thus with reduced wear) or from the action of residual eddy currents in a snubber bearing. A vertical displacement, up or down, of the lower pole element 34 will be reflected in a change in the force balance on the detached pole assembly 30. This change may result in a vertical displacement of the detached pole assembly 30, acting against supporting spring-like elements. A stationary drive screw 22 is attached to a supporting structure (not shown), and supports a rotatable assembly 24, which has an internal thread which matches the thread of stationary drive screw 22. Rotatable assembly 24 comprises a shunt pair 26 and a slotted pole pair 28 or a planar Halbach array 28. Rotatable bearing element 14 typically supports a rotor and is rotated by a drive mechanism (not shown).
- Figure 8 shows the central section of the converter with its main components
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Generally, this self-adjusting magnetic bearing is intrinsically radially stable and has a stationary bearing element and a rotatable bearing element that is magnetically levitated by the stationary bearing element. In one embodiment, an eddy current damper plate 80 is fixedly attached to a rotatable bearing element. Magnetic bearing element 37 is fixedly attached to the central axis of the stationary cup shaped element 36. The rotatable bearing element 34 may be an of iron disc.
Tipos De Dolor Torácico
It is also an object of the present invention to minimize the losses in a self-adjusting magnetic bearing such that the force equilibrium position of a suspended element is at the point where the repulsive force is minimal, so that eddy-current induced forces need only preserve stability in the close vicinity of the position of vertical force equilibrium. FIG. 3A shows a thermally controlled self-adjusting magnetic bearing. A pair of spaced discs in the stator are oppositely polarized by a permanent magnet, their peripheral magnetic field strength being selectively augmented or diminished in predetermined sectors by electromagnet windings thereon. By weakening the attractive force of the stationary bearing element 50, for example by an adjustment to the strength of the permanent magnet 54, a widening of the gap between the stationary element 50 and the rotatable element 70 will result, which in turn will result in a decrease in the repulsive force on the eddy current exciter 72, leading to a new and stable position of force equilibrium.
This torque may then actuate, either mechanically, or through a spring-loaded switch or potentiometer, electronic means that adjust the strength of the attractive pole so as to maintain vertical stability. This change in bearing design results in an overall design that permits the simplification of all the elements of the EM battery that operate within the vacuum housing.
With care in the design the end result is that the eddy current losses are minimized, while still maintaining a stable equilibrium, both axially and radially. In the way the damping force that is exerted on the rotating magnet (when its center is displaced radially as a result of the resonance), being perpendicular to the direction of the current, is directed nearly purely radially inward, i.e., with greatly reduced accompanying torque. A detached pole assembly 30 facilitates the stabilization of the rotor 32 against transverse “whirl” instabilities through the use of damping and/or spring-like elements 39 that support that assembly. A second embodiment achieves axial stabilization through a simplified electrical servo system. 2, presents another means for achieving axial stabilization, accomplished through a much-simplified electrical servo system. This second eddy current disc is supported by a drive shaft that is fixedly connected to the rotating disc 18. Dolor lumbar despues de epidural . The drive shaft passes through the hollow drive screw 22 to connect the rotating disc to the second eddy current disc.
A permanent magnet piece 58 is connected between the first cup 52 the second cup 54. A non-magnetic metallic piece 56 such as aluminum may be included between the two cup shaped elements 52 and 54. Another cup shaped element 60 made of magnetically conducting material 61 and non-magnetic metallic material 66 with two through holes is nested within cup shaped element 54. An eddy current plate 68 is supported by two support rods 62, 64 that extend from the eddy current plate 68 through the two through holes and are fixedly attached to the cup shaped element 54. Rotatable bearing element 70 is has an eddy current exciter 72 an a pole assembly 76 fixedly attached thereto. Another cup shaped element 54 of stationary element 50 also comprises magnetically conducting material. Note now that when the rotating eddy current exciter 72 is positioned close to the surface of the eddy current plate 68, heat will be generated in the eddy current plate 68, causing the thermostat element 65 to expand vertically, stretching springs 78. Since the eddy current plate 68 is restrained in position by the support rods 62 and 64, the expansion of the thermostat element 65 necessarily results in an upward motion of the movable pole of cup shaped element 60. This motion in turn weakens the attractive force of the upper stationary poles of stationary element 50 on the lower rotating poles of rotatable element 70, resulting in a lowering of the rotating parts to a new equilibrium position, one in which the heating is less.
Annular pole pieces 12 are separated with permanent magnet material 13. A generally disc shaped rotatable bearing element 14 is magnetically levitated by the stationary bearing element 10. Rotatable element 14 comprises annular iron pole pieces 16 which are attached to a rotatable disc 18. Pole pieces 16 are located directly across from the iron pole pieces 12 of the stationary element 10. Pole pieces 12 and pole pieces 16 are selected to exert magnetically attractive forces upon each other so that rotatable bearing element 14 tends to be pulled toward stationary upper bearing element 10. An annular conducting plate 20 is attached to the outer annular pole piece 16 of the rotatable bearing element 14. Como combatir el dolor de espalda . In this embodiment, the conducting plate 20 is made of copper, but may be made of any non-magnetic electrically conductive material.
That same element is used as a sensor for vertical displacements away from equilibrium of the lower bearing element that supports the rotor. 1-3 could replace the upper element 90 outside of vacuum housing 92. The lower bearing elements described in FIGS. It is not necessary that the system described be absolutely stable in the steady-state sense.
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Several options for this vertical stabilization have been described. When the frequency of this driving force coincides with the solid-body resonance, the amplitude of the vibration may build up to unacceptable high levels unless damping means are provided. One such resonance is the solid-body resonance frequency associated with the mass of the rotor and the transverse compliance of the bearing system. The magnetic field has a first magnetic field component which is constant around the periphery of the air gap and on which is superimposed a second magnetic field component which varies around the periphery of the air gap to absorb the transverse forces. FIG. Dolor de pierna izquierda y brazo izquierdo . 3B shows the relative rotation of magnetization of an eddy current exciter in a Halbach array configuration for use in an embodiment of the thermally controlled self-adjusting magnetic bearing of FIG. FIG. 3C shows a top view of a Halbach eddy current exciter with a representative pie shaped magnet piece for use in an embodiment of the thermally controlled self-adjusting magnetic bearing of FIG.
The eddy current-driven actuator thus performs a similar function to the electronic feedback circuits used in “active” magnetic bearings to maintain the bearing at the point of metastable equilibrium. In operation, a repulsive force is generated by the approach of slotted pole surface 28 to conducting plate (or a conducting cylinder) 20. Eddy currents thus generated will also generate a torque in the conducting plate 20, with a magnitude that is proportional to the force of repulsion. This being the case it only will take a watt or so in a typical-sized system to raise the temperature of the eddy current plate 68 by many tens of degrees Celsius. The function of the circular conducting rings is to insure that the eddy currents that are induced flow only in the azimuthal direction. 1, the shunt pair 26 is only actuated in a direction to weaken the field, that is, it would drive the lifting force down only.
In such an embodiment, drive screw 22 is hollow. In a first embodiment, a repulsive force is generated by the approach of a slotted pole surface to a conducting plate (or a conducting cylinder). The present invention relates to magnetic bearings, and more specifically, it relates to magnetic bearings that are intrinsically radially stable and are automatically stabilized axially. FIG. 3A shows a sectional view of a thermally adjusting magnetic bearing. An automatic means for adjusting the parameters of an axially unstable magnetic bearing is provided. The assembly includes radial bearing means holding the rotor on a desired axis of rotation and at least one magnet. For an electromechanical battery (EMB) storing about 5 kilowatt-hours, a watt of bearing losses, taken alone, would lead to a rundown time constant on the order of 5000 hours, which would be of essentially no consequence.
FIG. 5 shows the use of the embodiments of FIGS.
1-4 in an improved modular electromechanical battery. FIG. 4 shows an improved eddy-current damper for use in the embodiments of FIGS. This improved eddy-current damper assembly maximizes the desired damping effects on transversely directed vibrations, while minimizing the torque drag and other undesired effects that may be associated with the use of conventional eddy-current dampers. During the speed-up of the rotor, resonances may be encountered that could cause excessive lateral motions of the rotating system in the absence of damping. FIG. 5 shows the use of the embodiments of FIGS. Referring to the cross sectional view shown in FIG.