PURPOSE: To protect an eddy current tube against overheat by coupling the eddy current tube with a field means composed of a permanent magnet material having negative temperature characteristics such that heat can be conducted.
CONSTITUTION: Eddy current is generated in an eddy current tube 11 which rotates upon conduction of an exciting coil 20 thus obtaining brake torque. When brake action is sustained, temperature of the eddy current tube 11 rises due to Joule heat produced by the eddy current and the Joule heat is also transmitted to a field means thus raising the temperature thereof. Since the field means is constituted of a ferrite based permanent magnet 10 having negative temperature characteristics, interlinking flux of a generating coil 22 constituting an exciter decreases as the temperature of the field means rises. Consequently, output to the exciting coil 20 decreases thus decreasing eddy current. This constitution controls temperature of the eddy current tube 11 below a predetermined level.
AKITANI MASAZUMI
OSADA MASAHIRO
| JPH0415955U | 1992-02-10 | |||
| JPH0220174A | 1990-01-23 | |||
| JPS6443776A | 1989-02-16 |
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