PERMANENT MAGNET TYPE ROTOR

PURPOSE:To protect a permanent magnet and to improve the reliability in a permanent magnet rotor for motor by applying an outer circumferential protective tube onto the permanent magnet then applying stop boards at the opposite end sections in the axial direction of the permanent magnet and jointing the stop boards to the outer circumferential protective board. CONSTITUTION:Outer circumferential section of a permanent magnet 2 is protected by an outer circumferential protective tube 3 made of thin non- magnetic metal, while the opposite end sections in the axial direction of the permanent magnet 2 are protected by non-magnetic metal stop boards 4. Consequently, the permanent magnet 2 does not break down even if a permanent magnet type rotor is employed in a high output motor, and even if it is broken down such trouble as the chips being dispersed to the outside to cause secondary trouble can be prevented. The corrugation 3a of the outer circumferential protective tube 3 absorbs dimensional fluctuation of the permanent magnet 2. By such arrangement, reliability of permanent magnet is improved and productivity is also improved.