PERMANENT MAGNET TYPE ROTARY ELECTRICAL MACHINE

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PROBLEM TO BE SOLVED : To attain the challenge in which in a pump electric rotary machine for an LNG operated in an LNG liquid at -162°C, rare-earth magnets such as a neodymium magnet and a praseodymium magnet have at a low temperature such a characteristic as to shrink in a magnetization direction of a permanent magnet, but expand in a direction perpendicular to the magnetization direction, thereby requiring the need for considering linear expansion of an electromagnetic steel plate and a permanent magnet for a shape of a magnet insertion hole for inserting the magnet into the electromagnetic steel plate. SOLUTION : A permanent magnet constituting one pole in a rotor iron core of a permanent magnet rotor is halved about a magnetic pole, a connection portion as an electromagnetic steel plate is provided between the two division magnets, and arranged so that the center of the magnetic pole and a magnet magnetization direction are parallel with each other. A magnet insertion hole into which the permanent magnet is inserted is so shaped that a gap is provided between a plane perpendicular to the magnetization direction and an opposite plane of the electromagnetic steel plate at both ends of the permanent magnet in a width direction, a step portion having such a length that the height of the opposed surface is shorter than a thickness in the magnetization direction of the magnet is provided, and further a gap which extends in a direction perpendicular to the step toward a rotor outer-diameter side and a magnetic pole center side is provided outside the step. COPYRIGHT : (C)2013, JPO&INPIT