| 摘要 |
<p>PURPOSE:To enhance magnetic efficiency, and thereby make for compactness by forming each permanent magnet into each powerful thin type one so as to be incorporated in a magnet assembly, and thereby letting each exciting force the magnetic flux of which is equal in magnitude, but opposite in polarity to each permanent magnet, be generated in an exciting coil. CONSTITUTION:A first permanent magnet 2a thin in thickness is embedded in a position close to the releasing end side of an outer pole Po for a magnet assembly 3, and an inner permanent magnet 2b thin in thickness which is coaxial, but opposite in polarity, is also embedded in a free end side close to the armature 1 of an inner pole Pi at the side of a yoke releasing end. In a state that an exciting coil 11 is deenergized, the armature 1 is attracted to the magnet assembly against a spring plate 4 by the magnetic flux phim of each permanent magnet 2a and 2b, so that constant braking torque is thereby produced. When the exciting coil is energized by specified current, magnetic flux phi is produced, which is equal in magnitude to magnetic flux phim, but opposite in polarity, and the armature 1 is thereby released by the spring plate 4, so that braking torque becomes thereby zero. Torque can be controlled with magnetic flux adjusted to be ;m> ;c. By this constitution as mentioned above, efficiency can thereby be improved with each magnetic path made small in size.</p> |
