Motor

Patent metadata

Field	Value
Publication number	US-10084361-B2
Application number	US-201715716617-A
Country	US
Kind code	B2
Filing date	Sep 27, 2017
Priority date	Jun 26, 2014
Publication date	Sep 25, 2018
Grant date	Sep 25, 2018

Abstract

A motor includes a rotating portion with a shaft extending along a rotation axis and a rotor that rotates together with the shaft, a stationary portion with a stator located radially outside of the rotor and a magnetic sensor located above the rotor to detect a rotational position of the rotor. The rotor includes a rotor core, a rotor magnet located radially outside of the rotor core and under the magnetic sensor, in contact with the rotor core or located opposite to the rotor core with a first gap therebetween. A recessed portion is recessed from each of an upper end surface and an outer circumferential surface of the rotor core. An inner circumferential surface of a lower end portion of the rotor holder is fixed to a radially inner surface of the recessed portion.

First claim

What is claimed is:

1. A motor comprising:
a stationary portion; and
a rotating portion that rotates about a rotation axis extending in a vertical direction; wherein
the rotating portion includes:
a shaft extending along the rotation axis; and
a rotor that rotates together with the shaft;

the stationary portion includes:
a stator located radially outside of the rotor; and
a magnetic sensor located above the rotor to detect a rotational position of the rotor;

the rotor includes:
a rotor core including a ferromagnetic body fixed to the shaft;
a rotor magnet located radially outside of the rotor core and under the magnetic sensor, in contact with the rotor core or located opposite to the rotor core with a first gap intervening therebetween, and including an upper end surface located at an axial level higher than an axial level of an upper end surface of the rotor core; and
at least one rotor holder including a ferromagnetic body, and located above the rotor core and radially inside of the rotor magnet; wherein

the rotor core is defined by laminated steel sheets placed one upon another in an axial direction, and including a recessed portion recessed from each of the upper end surface and an outer circumferential surface of the rotor core; and
an inner circumferential surface of a lower end portion of the at least one rotor holder is fixed to a radially inner surface of the recessed portion.

2. The motor according to claim 1 , wherein a radial distance from the rotation axis to a radially inner surface of the rotor magnet and a radial distance from the rotation axis to a radially outer surface of the rotor core are equal or substantially equal to each other.

3. The motor according to claim 1 , wherein the at least one rotor holder is a cylindrical member extending along the rotation axis, and made of a stamped material.

4. The motor according to claim 3 , wherein
an inner circumferential surface of the rotor magnet is located radially opposite to the rotor core with the first gap defined therebetween;
the rotor magnet is located radially opposite to an inner circumferential surface of the rotor magnet with a second gap defined therebetween; and
a radial width of the first gap is smaller than a radial width of the second gap.

5. The motor according to claim 1 , wherein a radial distance from the rotation axis to the outer circumferential surface of the rotor core is equal or substantially equal to a radial distance from the rotation axis to an outer circumferential surface of the at least one rotor holder.

6. The motor according to claim 1 , wherein an axial position of the upper end surface of the rotor magnet and an axial position of an upper end surface of a portion of the at least one rotor holder which is adjacent to the rotor magnet are identical or substantially identical to each other.

7. The motor according to claim 1 , wherein the stator includes:
a stator core defined by laminated steel sheets placed one upon another in the axial direction;
a plurality of coils attached to the stator core; and
the stator core has an axial dimension equal or substantially equal to an axial dimension of the rotor core.

8. The motor according to claim 7 , wherein
a lower end surface of the rotor magnet is positioned at an axial level lower than an axial level of a lower end surface of the rotor core; and
the at least one rotor holder includes:
a first rotor holder located above the rotor core and radially inside of the rotor magnet; and
a second rotor holder located below the rotor core and radially inside of the rotor magnet.

9. The motor according to claim 8 , wherein the rotor magnet is annular and is centered on the rotation axis.

10. The motor according to claim 9 , wherein an outer circumferential surface of the shaft includes a knurled portion.

11. The motor according to claim 10 , wherein an adhesive is provided between the rotor core and the rotor magnet and also between the at least one rotor holder and the rotor magnet.

Assignees

• Nidec Corp

Inventors

• Kitaji Kazuya
• Nagasawa Jun
• Furukawa Keizo

Classifications

• H02K1/30

  using intermediate parts, e.g. spiders · CPC title

• H02K11/215 Primary

  Magnetic effect devices, e.g. Hall-effect or magneto-resistive elements · CPC title

• H02K29/08

  using magnetic effect devices, e.g. Hall-plates, magneto-resistors (H02K29/12 takes precedence) · CPC title

• H02K1/2733 Primary

  Annular magnets · CPC title

• H02K1/16

  Stator cores with slots for windings · CPC title