Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2001-07-12
2004-10-19
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C505S166000
Reexamination Certificate
active
06806604
ABSTRACT:
BACKGROUND OF THE INVENTION
1. The Field of the Invention
The present invention relates to centrifuges and, more specifically, centrifuges wherein a magnetic force levitates and stabilizes at least a portion of the rotor system thereof.
2. The Relevant Technology
From DT 23 14 436 A1 a bearing and a damping system is known for the stabilization of a fast rotating centrifuge. The rotor is guided stable in the position without a mechanical connection between the rotor and the surrounding. The stabilizing forces are magnetic in nature with an additional damping system produced by magnetic, mechanical-hydraulic, and hydropneumatic forces interacting with the rotor.
In this prior invention the combination and interaction of different damping factors and their coupling to the rotor is difficult to realize and requires an extremely high technical expense.
U.S. Pat. No. 5,196,748 discloses a laminated structure of a superconducting magnetic bearing. The reference discloses at least two permanent magnets in opposite polarity which are sandwiched causing a high magnetic flux density gradient and hence a high stiffness. The magnetic structure is inside a superconducting hollow cylinder.
Furthermore, DE 42 32 869 A1 discloses a superconducting bearing and a corresponding procedure for operation. The bearing system comprises a shaft encircled by permanent magnetic rings and a superconducting body, each of the elements being disposed within a housing. The superconducting body is shaped so that it is cooled down as the shaft is upwardly moved to a position where the rotating shaft is in balance between the weight of the shaft and the magnetic forces applied to the shaft by the interaction between the magnets and the superconductor.
The primary disadvantage of the above system is the complicated in-operation procedure whereby the rotor with the permanent magnets are located close to the superconductor following which a field frozen cooling down procedure is used to reach the superconducting stage. This standby procedure is less reproducible with respect to the rotor position and is a tedious pre-operation procedure.
BRIEF SUMMARY OF THE INVENTION
It is therefore an object of one embodiment of the present invention to design and construct a centrifuge and a method of use thereof so that during centrifugation the rotor is magnetically stabilized by one or two bearings and operates substantially free of mechanical contact and friction. It is a further object of one embodiment of the invention to use superconducting magnetic bearings to prevent or at least minimize the use and maintenance of the enormous electric and electronic circuit equipment of conventional active magnetic bearing designs.
In one embodiment, the material utilized for designing and constructing bearings is “high-temperature superconducting (HTS)”, which has been shortened herein to “superconducting”. Furthermore, the term “permanent magnet” is frequently abbreviated to “PM”.
It is yet another object of one or more of the embodiments of the present invention to achieve high speed operation up to 180,000 RPM, substantial damping properties, low vibrating noise of the rotor shaft, and/or less driving power as well as safe operation with highly unbalanced rotor systems. A high bearing damping factor is desired at all operational frequencies. The damping should be independent of the actual speed.
The above objects are achieved in one embodiment with at least one permanent magnet configuration arranged at a distance in front of a passive superconducting magnet stator so as to produce an improved superconducting magnetic bearing.
Especially advantageous is the passive and self-stabilizing character of the bearing without any electronic control. As a result, the expenditure of the system is substantially reduced. The bearing allows a relative robust operation in experiment and processing.
In a preferred embodiment of the invention the permanent magnets are arranged so that the resulting magnetic flux distribution is directed almost normally to adjacent interacting surfaces of permanent magnets and superconductor.
In another preferred embodiment of the invention the rotor axis encircles an angel from 0 to 90 degrees relative to a horizontal plane.
In a highly preferred embodiment of the invention the rotor system has at least one ring or cylinder-shaped permanent magnet configuration and adjacent in radial direction a passive superconducting magnet stator.
In a first preferred embodiment of the invention the permanent magnet of the rotor is surrounded partly or totally by the superconducting stator element.
In a second preferred embodiment the permanent magnet configuration of the rotor concentrically surrounds the HTS magnet stator.
The rotor design advantageously consists of one PM configuration which at least in the axial direction is adjacent to at least one passive superconducting magnet stator. In another embodiment the permanent magnet configuration is attached on a shaft or a shaft-shaped part along the rotor axis. In the case of a multiple bearing design, at least one stator surrounds the shaft or part of the shaft.
In a further preferred embodiment of the centrifuge the permanent magnet configuration is fixed in a hollow cylinder-shaped shaft of the rotor or is designed as a hollow cylinder-shaped shaft. For more than one bearing, the hollow shaped shaft surrounds at least one stator.
The present invention also envisions a combination with a rotor arrangement with at least one PM configuration which is radially directed adjacent to a superconducting magnet stator and in addition is simultaneously adjacent to an axial magnet stator.
In a further preferred embodiment the passive superconducting magnet stator is connected with a cryogenic unit. The stator is at least partly shaped as a hollow cylinder. In one embodiment, the stator is a monolithic hollow cylinder of melt textured YBCO material with a critical temperature of 92 K equivalent −181° C. The preferred stator material is polycrystalline melt textured material of the composition Y
13-17
Ba
2
Cu
3
O
7-&dgr;
. The material shows a multi-domain magnetic structure with advantageous damping properties produced by the material grain boundaries for the magnetic bearing.
In an additional preferred embodiment the stator includes damping rings of copper, aluminum or alloys thereof. The damping devices can either be sandwiched and thermally connected between individual superconductors or fitted into the superconducting components.
The superconducting magnet stator is connected with a cryogenic engine inside the centrifugal housing in order to cool down the superconductor below its critical temperature. Alternatively, the superconductor can be cooled in an economical way by liquid Nitrogen to a temperature of 77 K or equivalent −196° C.
In an alternative embodiment at least a portion of the superconducting magnet stator has a hollow cylinder or a ring shape with at least one lateral open segment or sector window.
The permanent magnet configuration in one embodiment has a ring or cylinder shape and is arranged coaxially with respect to the rotor axis.
According to another embodiment the permanent magnet configuration comprises as a ring or cylinder shaped PM. A plurality of co-axial rings and hollow cylinders are stacked directly or with another material therebetween in radial and/or axial direction.
One preferred embodiment of the centrifuge has a PM configuration comprising axial magnetized rings stacked or sandwiched in axial direction so that adjacent magnet surfaces are magnetized to the same polarity. As a result of the equation of continuous magnetic flux flow the desired high magnetic flux density expands radially of the rotatable member.
According to another embodiment of the centrifuge, at least two annular PM's are coaxially fitted one in another in a common plane whereby the outer diameter of the smaller ring touches the inner diameter of the larger ring. The rings can be repulsive or attract each other by having adjacent PM faces either in the same or
Betke Viktor
Flögel-Delor Uta
Jaeckel Ingo
Kopp Dietmar
Werfel Frank
Aguirrechea J.
Baker & Hostetler LLP
Kendro Laboratory Products GmbH
Nguyen Tran
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