| 摘要 |
PROBLEM TO BE SOLVED: To allow a permanent magnet of a low Curie point to be used while the clamp strength of the permanent magnet is enhanced by reducing the heat in a holding ring which reinforces clamping of the permanent magnet. SOLUTION: A non-magnetic thin metal ring 3 is tightly wound around a permanent magnet 2 which forms the rotor 1, around which a fiber ring 4 is wound in which a high-tension material such as carbon fiber is molded with resin. The fiber ring 4 is a non-magnetic insulator which allows a magnetic flux to pass while blocking the current. The distribution of magnetic flux near the permanent magnet 2 is even, but it becomes irregular as it approaches the stator 5 because the magnetic flux concentrates at a fixed magnetic pole 6. So, the eddy current loss is less and the heat is also less in the metal ring whose magnetic flux distribution is even. Meanwhile, the fiber ring 4 whose magnetic flux distribution is irregular does not generate heat because an eddy current does not flow as it is an insulator. Since the permanent magnet 2 generates least heat, a magnet of neodymium compound which is inexpensive and has a ferromagnetic characteristics at a normal temperature can be used.
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