# US 10,312,757 B2 · Permanent magnet rotor for synchronous electric motor

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- Number: US 10,312,757 B2
- Document ID: US10312757B2
- Status: Granted
- Kind: B2
- Application number: 15/290,017
- Filed: 2016-10-11
- Published: 2017-04-27
- Granted: 2019-06-04
- Earliest claimed: 2015-10-22
- Assignees: Fanuc Corporation
- Applicants: Fanuc Corporation
- Inventors: Akira Nishifukumoto; Hidetoshi Mitsui
- Web page: https://patentgrep.com/patent/US10312757B2

## CPC

- H02K 1/28: Means for mounting or fastening rotating magnetic parts on to, or to, the rotor structures
- H02K 1/278: Surface mounted magnets; Inset magnets
- H02K 29/03: with a magnetic circuit specially adapted for avoiding torque ripples or self-starting problems
- H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53})

## Abstract

Provided is a permanent magnet rotor that includes a plurality of magnets sequentially disposed on an outer circumferential surface of a core having a cylindrical shape along a circumferential direction of the core and a plurality of projection portions each disposed between the magnets adjacent to each other. Then a cover portion is formed such that a height of a space in a radial direction of the core is more reduced as from a base portion of the projection portions toward a tip end of the cover portion.

## Claims

### Claim 1

A permanent magnet rotor for an electric motor, comprising:
a core having a cylindrical shape;
a plurality of magnets sequentially disposed on an outer circumferential surface of the core along a circumferential direction of the core, each magnet has a circumferential end surface; and
a plurality of projection portions each disposed between the magnets adjacent to each other, an axial length of each projection portion being smaller than an axial length of the core, wherein
a thickness of the magnets in a radial direction of the core is smaller as from a center portion of the magnets toward an end portion of the magnets in the circumferential direction of the core,
the projection portions include;
a base portion that projects from the outer circumferential surface of the core to a radial direction outer side of the core, the base portion has a circumferential end surface circumferentially spaced apart from the circumferential end surface of the magnet adjacent to the projection portion; and
a cover portion that extends from the base portion in the circumferential direction of the core so as to be separate away from an outer surface of the magnet, and covers the end portion of the magnets through a space, the cover portion being not provided with a portion which is in contact with the outer surface of the magnet, and
the cover portion is formed such that a height of the space in the radial direction of the core is more reduced as from the base portion toward a tip end of the cover portion.