Brakes – Operators – Electric
Patent
1998-01-09
2000-03-28
Schwartz, Chris
Brakes
Operators
Electric
188161, B60L 728
Patent
active
060418974
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION
The invention relates generally to a magnetic brake, and particularly a linear eddy-current brake for rail vehicles.
Increased attention is being paid to eddy-current brakes, particularly within the scope of the further development of high-speed trains. The reason is that, since these eddy-current brakes do not contact the rail when braking, they do not wear out and can therefore be maintained at reasonable cost. A short introduction into the technology of eddy-current brakes for rail vehicles--whose function is based on the law of induction--is found, for example, in the book by Saumweber, et al "AET--Archiv fur Eisenbahntechnik" ("Archive for Railroad Technology"), Hestra Publishers, Volume 43, Chapter 2.5.2". Accordingly, eddy-current brakes consist of an iron yoke with several pole cores. Electric coils magnetically excite the brake such that magnetic north and south poles are formed in an alternating manner. When the excited eddy-current brake is moved over the rail--that is, when braking --, magnetic fields are formed which are caused by eddy currents and which result in the braking force.
The invention is aimed at improving the construction of eddy-current brakes.
The invention achieves this goal by providing a magnetic brake, particularly a linear eddy-current brake for rail vehicles, which has a magnet yoke extending almost along the whole length of the eddy-current brake and which, in the installed position, has a concave exterior shape at least toward the rail.
The invention is based on the recognition that the application forces generated during the operation of an eddy-current brake may lead to an elastic bending of the brake (see FIG. 4). Furthermore, the rail may bend because of the normal forces of the axles (see FIG. 5; for example, in the shunt area). In addition, the rail may, under certain circumstances, be raised slightly in the area of the shunts as a result of the attraction force of the magnets.
The above-described effects have the result that the air gap between the rail and the brake is not constant along the total length of the brake. When the air gap is adjusted, the minimal value in the center of the brake must be taken into account.
The invention remedies this effect in that the concave shaping results in a compensation of the bending in the sense of an at least largely uniform linear course of the air gap.
Advantageous further developments of the invention are found herein.
In the following, the invention will be explained in detail with reference to the drawing, in which case additional advantages of the invention are also illustrated.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic representation of a first embodiment of the invention;
FIG. 2 is a schematic representation of a second embodiment of the invention;
FIG. 3 is a schematic representation of the operating method of the invention;
FIGS. 4 and 5 are views of the effect of the bending of the rail and the brake according to the state of the art.
FIG. 6 is a schematic representation of a stepped embodiment.
FIG. 7 is a schematic cross section of a stepped embodiment of FIG. 6 with stepped coils.
FIG. 8 is a cross section including a protective housing.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 will be described first. FIG. 1 is a schematic representation of an eddy-current brake 1 which has a concave shape on its underside pointing to the rail 2 (such as the milled-out area of the magnet yoke ranging from 0 mm at the edge to 1-5 mm in the center of the brake). FIG. 2 shows a variant of this idea in the case of which the brake is plasmically preformed such that a concave deformation is created toward the rail 2. As the result of the invention, the effect of the bending of the brake during the operation is compensated in an uncompleted manner; for, if the brake is bent during the operation by approximately 5 mm, it will be virtually plane in the operation if it is correspondingly preformed.
The concave shape preferably extends in a continuous manner. H
REFERENCES:
patent: 3723795 (1973-03-01), Baermann
patent: 3805927 (1974-04-01), Tolksdorf
patent: 3840096 (1974-10-01), Tolksdorf
patent: 4122922 (1978-10-01), Baermann
patent: 4144954 (1979-03-01), Farello et al.
patent: 4482034 (1984-11-01), Baermann
patent: 5653173 (1997-08-01), Fischer
patent: 5668421 (1997-09-01), Gladish
patent: 5862891 (1999-01-01), Kroger et al.
Grautstuck Heinrich
Kroger Uwe
Saumweber Eckart
Knorr-Bremse System Fur Schienenfahrzeuge GmbH
Schwartz Chris
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