US Patent No. 9,065,314

ROTOR OF BURIED MAGNET-TYPE ELECTRIC MOTOR, MOTOR AND MACHINE TOOL HAVING THE ROTOR


Patent No. 9,065,314
Issue Date June 23, 2015
Title Rotor Of Buried Magnet-type Electric Motor, Motor And Machine Tool Having The Rotor
Inventorship Yohei Arimatsu, Minamitsuru-gun (JP)
Kenji Kawai, Minamitsuru-gun (JP)
Assignee FANUC CORPORATION, Yamanashi (JP)

Claim of US Patent No. 9,065,314

1. A rotor of a buried magnet-type electric motor, said rotor comprising:
magnetic poles each including two rows of magnets of the same pole wherein the two rows of magnets are placed side by side;
and

a core including, for each of the magnetic poles,
magnet slots in which said two rows of magnets are arranged, and
a core portion between the magnet slots,
wherein each of the magnet slots includes:
a bottom edge on an inner side in a radial direction of the rotor, and
connecting portions that connect the bottom edge to a corresponding outer edge of the core portion,
wherein said connecting portions include:
a first curved portion having a smaller curvature and connected to the bottom edge, and
a second curved portion having a larger curvature and connected to the corresponding outer edge of said core portion,
wherein a first tangential line at a first connecting point between the first curved portion and the bottom edge is a tangential
line common for the first curved portion and the bottom edge, and

wherein a second tangential line at a second connecting point between the second curved portion and the corresponding outer
edge of the core portion is a tangential line common for the second curved portion and the corresponding outer edge of the
core portion.