Brakes – Operators – Electric
Reexamination Certificate
1999-03-31
2001-05-29
Oberleitner, Robert J. (Department: 3613)
Brakes
Operators
Electric
C188S161000, C310S105000
Reexamination Certificate
active
06237728
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an eddy current reduction braking system, which increases both heat dissipation and braking torque.
In a magnet type eddy current reduction apparatus disclosed in Japanese Patent Publication No. 3-86,050 Publication or the like, a magnet supporting tube is reciprocated in an axial direction to switch between braking and non-braking conditions. Such apparatus has the inherent disadvantage of increasing space requirements in the axial direction.
In a magnet type eddy current reduction apparatus disclosed in Japanese Patent Publication No. 7-118,901 Publication or the like, a movable magnet supporting tube is rotated to adjust the relative polarities of magnets axially adjacent in a pair of axially aligned magnet arrays to switch between braking and non-braking conditions. In such an apparatus, however, each pair of N and S-poles of each magnet are directed in a radial direction of the brake drum. It is therefore necessary to process outer and inner surfaces of the magnets into cylindrical or circular form so that an effective magnetic flux is applied to the brake drum via a ferromagnetic plate. The required magnet processing considerably increases cost. Furthermore, the ferromagnetic plates must be large so as to completely cover the magnets in the braking condition. Complete covering by the plates allows the magnets to apply a magnetic field to the brake drum without any substantial leakage. Magnetic flux density cannot be effectively increased to improve braking force therefore due to ferromagnetic plate limitations.
The object of the present invention, therefore, is to provide an eddy current reduction apparatus which is compact in its entirety, and in which braking performance is enhanced.
SUMMARY OF THE INVENTION
The invention is a braking system including a brake drum coupled to a rotational shaft, an immovable magnet supporting tube and a movable magnet supporting tube aligned in an axial direction and disposed coaxially within the brake drum, and an array of permanent magnets supported at equal intervals on an outer peripheral wall of each magnet supporting tube. In addition, proximal surfaces of a pair of ferromagnetic pole pieces are fixed to magnetic pole surfaces at both ends of each magnet. The pole pieces project annularly from each permanent magnet, and extreme end surfaces thereof are juxtaposed to an inner peripheral surface of the brake drum. Motive member actuators reversibly rotate the movable magnet supporting tube to provide braking and non-braking conditions.
According to certain features of the invention, each magnet is supported on its magnet supporting tube with N and S poles oriented annularly and the ferromagnetic pole pieces extend in both the annular direction and in a radially outward direction. In addition, the outer peripheral surfaces of the immovable magnet supporting tube and the movable magnet supporting tube arranged are covered by an extremely thin outer tube portion formed of a non-magnetically permeable material to protect against dust and muddy water.
REFERENCES:
patent: 4937483 (1990-06-01), Matsui et al.
patent: 5054587 (1991-10-01), Matsui et al.
patent: 5143183 (1992-09-01), Kuwahara
patent: 5303802 (1994-04-01), Kuwahara
patent: 5337862 (1994-08-01), Kuwahara
patent: 5650679 (1997-07-01), Boggs, III et al.
patent: 5804897 (1998-09-01), Kuwahara
patent: 6039157 (2000-03-01), Yamada et al.
Kobayashi Shin
Narumi Yukitoshi
Isuzu Motors Limited
Jarcho Harold G.
Oberleitner Robert J.
Rodriguez Pamela J.
Toupal John E.
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