# US 11,309,750 B2 · Motor with optimized dimensional relationships

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- Number: US 11,309,750 B2
- Document ID: US11309750B2
- Status: Granted
- Kind: B2
- Application number: 16/634,672
- Filed: 2018-07-27
- Published: 2020-07-02
- Granted: 2022-04-19
- Earliest claimed: 2017-08-02
- Assignees: MINEBEA MITSUMI Inc.
- Applicants: MINEBEA MITSUMI Inc.
- Inventors: Makoto Otsuka; Koji Kebukawa
- Web page: https://patentgrep.com/patent/US11309750B2

## CPC

- H02K 1/16: Stator cores with slots for windings
- H02K 1/146: {consisting of a generally annular yoke with salient poles}
- H02K 1/2706: Inner rotors
- H02K 1/2733: Annular magnets
- H02K 15/021: Magnetic cores
- H02K 21/16: having annular armature cores with salient poles (with homopolar co-operation H02K21/20)
- H02K 1/02: characterised by the magnetic material
- H02K 7/14: Structural association with mechanical loads, e.g. with hand-held machine tools or fans (with fan or impeller for cooling the machine H02K9/06)
- H02K 2213/03: Machines characterised by numerical values, ranges, mathematical expressions or similar information
- H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53})

## Abstract

A driving apparatus according to an embodiment includes an arm, an operation target, and a brake unit. The arm has one end supported by a support mechanism, and includes an electric driving source. The operation target is attached to the other end of the arm, the other end being an end on the opposite side of the one end, and is enabled to be pivoted by the driving source about one rotational axis intersecting with a direction from the one end to the other end. The brake unit secures immobility of a target gear that is a gear disposed in the arm, and that is a gear being rotated as the operation target is pivoted, when the power supply to the driving source stops.

## Claims

### Claim 1

A motor comprising:
a stator including a yoke and teeth that protrude from the yoke; and
a rotor having an outside diameter a ratio of which to an outside diameter of the stator is equal to or less than 0.3, wherein
the stator has a thickness of the yoke a ratio of which to the outside diameter of the stator is 0.1 to 0.15, and the stator has an air gap formed between the teeth and the rotor, and a ratio of the air gap to the outside diameter of the stator is 0.042 to 0.064.

### Claim 2 (depends on 1)

The motor according to claim 1, wherein the outside diameter of the stator is equal to or less than 50 mm.

### Claim 3 (depends on 1)

The motor according to claim 1, wherein a rotational speed of the motor is equal to or greater than 50,000 rpm.