Inner-rotor brushless motor

Patent metadata

Field	Value
Publication number	US-9893590-B2
Application number	US-201414567029-A
Country	US
Kind code	B2
Filing date	Dec 11, 2014
Priority date	Apr 28, 2014
Publication date	Feb 13, 2018
Grant date	Feb 13, 2018

Abstract

A rotor portion includes an upper cylindrical portion and a lower cylindrical portion, each of which is configured to rotate together with a rotor. A stator portion includes a circuit board including a rotation detection portion located thereon. The lower cylindrical portion includes a lower balance correction portion. The upper cylindrical portion includes an upper balance correction portion. In addition, a detectable portion configured to be detected by the rotation detection portion is provided on the upper cylindrical portion.

First claim

What is claimed is:

1. An inner-rotor brushless motor comprising:
a rotor portion including a shaft extending in a vertical direction along a central axis;
a stator portion located radially outside of the rotor portion; and
a bearing portion configured to support the rotor portion with respect to the stator portion; wherein
the rotor portion includes:
a rotor configured to rotate together with the shaft, and including at least one magnet; and
an upper cylindrical portion and a lower cylindrical portion located axially above and below, respectively, the rotor, and configured to rotate together with the rotor;

the stator portion includes:
a stator located radially opposite to the rotor with a gap intervening therebetween;
a housing configured to hold the stator;
a cap located axially above the housing; and
a circuit board held by one of the housing and the stator, and including a rotation detection portion located thereon;

the bearing portion includes:
an upper bearing configured to rotatably support the shaft and held by the cap axially above the stator; and
a lower bearing configured to rotatably support the shaft and held by the housing axially below the stator;

the lower cylindrical portion includes a lower balance correction portion;
the upper cylindrical portion includes a detectable portion configured to be detected by the rotation detection portion located thereon, and includes an upper balance correction portion; and
the upper cylindrical portion includes a member on which the detectable portion is provided, the member being separate from the upper balance correction portion.

2. The brushless motor according to claim 1 , wherein the upper balance correction portion is located axially above the member on which the detectable portion is provided.

3. The brushless motor according to claim 2 , wherein the upper balance correction portion is located axially opposite to the upper bearing with a gap intervening therebetween.

4. The brushless motor according to claim 3 , wherein the upper balance correction portion includes one of a raised portion projecting in an axial direction and a recessed portion which is cut in the axial direction.

5. The brushless motor according to claim 1 , wherein the lower balance correction portion is located axially opposite to the lower bearing with a gap intervening therebetween.

6. The brushless motor according to claim 5 , wherein
the upper balance correction portion is located axially below the upper bearing; and
the lower balance correction portion is located axially above the lower bearing.

7. The brushless motor according to claim 4 , wherein
the rotor further includes a rotor core;
the rotor core includes a plurality of holes arranged to pass therethrough in the axial direction; and
each of the at least one magnet is inserted in one of the holes.

8. The brushless motor according to claim 4 , wherein
the rotor further includes a rotor core; and
each of the at least one magnet is arranged on a radially outer circumference of the rotor core.

9. The brushless motor according to claim 6 , wherein
the rotor further includes a rotor core;
the rotor core includes a plurality of holes arranged to pass therethrough in the axial direction; and
each of the at least one magnet is inserted in one of the plurality of holes.

10. The brushless motor according to claim 6 , wherein
the rotor further includes a rotor core; and
each of the at least one magnet is located on a radially outer circumference of the rotor core.

11. The brushless motor according to claim 4 , wherein the upper balance correction portion is axially asymmetric with respect to the central axis.

12. The brushless motor according to claim 6 , wherein the lower balance correction portion is axially asymmetric with respect to the central axis.

13. The brushless motor according to claim 1 , wherein
the stator includes an upper insulator arranged to cover a portion of the stator;
the circuit board includes, at a radially outer circumference thereof, a plurality of circuit board projection portions each of which is projecting radially outward;
the upper insulator includes at least one snap-fit portion projecting axially upward; and
each of the at least one snap-fit portion is fitted to one of the plurality of circuit board projection portions to fix the circuit board.

14. The brushless motor according to claim 13 , wherein
the stator includes a conducting wire;
the housing includes a housing cylindrical portion including a cut defined therein; and
the conducting wire is connected to an external connector arranged outside of the housing cylindrical portion through the cut.

15. An electrical appliance comprising the brushless motor of claim 1 .

Assignees

• Nidec Corp

Inventors

• Sawada Tomoyoshi
• Oura Yuya

Classifications

• H02K7/04 Primary

  Balancing means · CPC title

• H02K29/08

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

• H02K3/522

  for generally annular cores with salient poles · CPC title

• H02K5/161

  radially supporting the rotary shaft at both ends of the rotor (H02K5/165, H02K5/167, H02K5/173 take precedence) · CPC title