Brakes – Operators – Electric
Reexamination Certificate
2000-07-28
2001-12-11
Butler, Douglas C. (Department: 3613)
Brakes
Operators
Electric
C188S164000, C188S267000, C188S382000
Reexamination Certificate
active
06328142
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic eddy-current braking apparatus for assisting a frictional brake of a vehicle, and more particularly, to an eddy-current braking apparatus provided with a tube for protecting permanent magnets.
In a conventional eddy-current braking system provided with one or more magnet support tubes, relatively thick (approximately 10 to 16 mm) ferromagnetic plates have been used with a tube formed of a nonmagnetic material in order to prevent leakage of magnetic flux from permanent magnets. To accomplish the above, a magnetic plate is cast into a tube body formed of aluminum, or a tube is formed by a deformation process from stainless steel plate as a nonmagnetic material and ferromagnetic pole pieces are fitted into a number of openings provided in the tube and connected by welding. In the former method, manufacturing is difficult, and the yield or available percentage of aluminum cast product as a tube is poor. Further, according to the former method, the connecting strength between the magnetic pole pieces and the aluminum body of the tube is so weak that impregnating material or the like is filled into the clearances. Further, the manufacturing cost increases because of machining tolerances, when the outer peripheral surface of the tube opposite to the inner peripheral surface of the brake drum and the inner peripheral surface opposite to the magnets are subjected to required machining. Also in the latter method, it is difficult to reduce the cost of manufacturing because of costs associated with welding the magnetic plates to the tube.
In view of the aforementioned problems, the object of the present invention is to provide an eddy-current deceleration apparatus which is easier and less expensive to manufacture.
SUMMARY OF THE INVENTION
To solve the aforementioned problems, according to the present invention, a protective guide tube is formed of stainless steel as a magnetic material, and portions not opposite to the permanent magnets are dissolved in a high temperature state and rapidly cooled into a nonmagnetic or weak magnetic austenite phase.
The guide tube covering a magnet support tube is manufactured from a seamless steel pipe formed of martensite stainless steel having a wall thickness of 10 to 16 mm as a magnetic material or a steel pipe made from steel plate. Portions opposite to the magnets of the outer guide tube remain magnetic, and portions not aligned with the magnets are rapidly cooled after being heated to a high temperature of 800 to 1350 degrees Centigrade (in a partial solution state) thereby creating nonmagnetic portions or weak magnetic portions so as to prevent magnetic short-circuiting (magnetic short) in the guide tube during braking. The stainless steel used as magnetic material can be, for example, 13 chromium (Cr) stainless steel, 17 chromium (Cr) ferrite stainless steel, and the like. The tube formed of stainless steel is cut out to form an outer guide tube such that thick portions (magnetic plates, thickness of 10 to 16 mm) opposite to magnets and thin portions not opposite to magnets are arranged alternately in a peripheral direction. Since the thick portions maintain the characteristics of a magnetic material, and the thin portions are converted into non-magnetic or weak magnetic material, the operation and effect similar to the conventional outer guide tube is obtained with a reduction in manufacturing cost and weight. In place of machining the thin portions from a thick tube of stainless steel, there can be employed alternatively a method in which thick portions of magnetic plates opposite to magnets and thin portions not opposite to magnets are formed by casting or forging a pipe of stainless steel as a magnetic material, and the thin portions thereof heated to a high temperature state in not less than 800 degrees Centigrade (in a partial solution state) and subsequently rapidly cooled into a non-magnetic or weak magnetic austenite phase.
REFERENCES:
patent: 5023499 (1991-06-01), Kuwahara
patent: 5145038 (1992-09-01), Kuwahara
patent: 5303802 (1994-04-01), Kuwahara
patent: 5804897 (1998-09-01), Kuwahara
patent: 5855256 (1999-01-01), Kuwahara
patent: 6025664 (2000-02-01), Kuwahara
patent: 6039157 (2000-03-01), Yamada et al.
patent: 6176355 (2001-01-01), Yamamoto
patent: 6209688 (2001-04-01), Kuwahara
patent: 6237728 (2001-05-01), Kobayashi et al.
patent: 11235005 (1999-08-01), None
patent: 102239 (2000-04-01), None
patent: 102240 (2000-04-01), None
Butler Douglas C.
Isuzu Motors Limited
Jarcho Harold G.
Toupal John E.
LandOfFree
Eddy-current deceleration apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Eddy-current deceleration apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Eddy-current deceleration apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2572541