Brushless motor assembly for a fastening tool

Patent metadata

Field	Value
Publication number	US-11081933-B2
Application number	US-201816169435-A
Country	US
Kind code	B2
Filing date	Oct 24, 2018
Priority date	Dec 18, 2014
Publication date	Aug 3, 2021
Grant date	Aug 3, 2021

Abstract

An electric brushless DC motor is provided including an outer rotor assembly having a metallic rotor body, rotor magnets mounted within an inner surface of the rotor body, and a molded structure formed within the rotor body. The molded structure includes at least one of: a main body formed on inner surface of the rotor body to securely cover and retain the rotor magnets on the inner surface of the rotor body, an axial fan formed at an end of the rotor body opposite the rotor magnets, and/or a sense magnet mount formed at approximately a radial center portion of the axial fan.

First claim

The invention claimed is:

1. An electric brushless DC (BLDC) motor comprising:
an outer rotor assembly having a substantially-cylindrical metallic rotor body, a plurality of rotor magnets mounted within an inner surface of the rotor body, and a flywheel having a plurality of annular rings formed on an outer surface of the rotor body;
a molded structure formed within the rotor body formed on an inner surface of the rotor body to securely cover and retain the rotor magnets on the inner surface of the rotor body, the molded structure further comprising at least one radial member projecting inwardly from the main body towards a center of the outer rotor assembly, and a bearing support member having a substantially cylindrical shape in an axial direction of the outer rotor and supported by the at least one radial member; and
a stator assembly received inside the outer rotor assembly and mounted on a shaft,
wherein the at least one radial member is oriented radially in-line with at least a portion of the flywheel.

2. The electric motor of claim 1 , wherein the molded structure comprises at least one of a proxy, plastic, or resin material.

3. The electric motor of claim 1 , wherein the flywheel is integrally formed on the outer surface of the rotor body.

4. The electric motor of claim 1 , wherein the molded structure integrally comprises a radial member projecting inwardly from the main body towards a center of the outer rotor assembly, the radial member forming a sense magnet mount at an end of the rotor body, wherein the electric motor further comprises a sense magnet supported by the sense magnet mount.

5. The electric motor of claim 4 , further comprising an end cap affixed to an end of the outer rotor assembly opposite the stator assembly, the end cap including a positional sensor board disposed in close axial proximity to the sense magnet.

6. The electric motor of claim 1 , wherein the molded structure integrally comprises an axial fan formed at an end of the rotor body opposite the rotor magnets.

7. A power tool comprising a housing and an electric brushless DC (BLDC) motor according to claim 1 disposed within the housing.

8. An electric brushless DC (BLDC) motor comprising:
an outer rotor assembly having a substantially-cylindrical metallic rotor body, and a plurality of rotor magnets mounted within an inner surface of the rotor body;
a molded structure formed within the rotor body formed on an inner surface of the rotor body to securely cover and retain the rotor magnets on the inner surface of the rotor body, the molded structure further comprising at least one radial member projecting inwardly from the main body towards a center of the outer rotor assembly, and a bearing support member having a substantially cylindrical shape in an axial direction of the outer rotor and supported by the at least one radial member;
a stator assembly received inside the outer rotor assembly and fixedly mounted on a shaft; and
at least one bearing located within the bearing support member and mounted on the shaft to rotationally support the outer rotor assembly relative to the shaft.

9. The electric motor of claim 8 , wherein the molded structure comprises at least one of a proxy, plastic, or resin material.

10. The electric motor of claim 8 , the outer rotor assembly further comprising a flywheel integrally formed on an outer surface of the rotor body.

11. The electric motor of claim 8 , further comprising an end cap affixed to an end of the outer rotor assembly opposite the stator assembly, the end cap including a positional sensor board disposed in close axial proximity to the sense magnet.

12. The electric motor of claim 8 , wherein the molded structure integrally comprises an axial fan formed at an end of the rotor body opposite the rotor magnets.

13. A power tool comprising a housing and an electric brushless DC (BLDC) motor according to claim 8 disposed within the housing.

Assignees

• Black & Decker Inc

Inventors

• Fogle John B
• Crosby Colin M
• Smith David J
• Tennison Merritt J
• Purohit Madhur M

Classifications

• H02K29/08 Primary

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

• H02K1/2791

  Surface mounted magnets; Inset magnets · CPC title

• H02K1/28

  Means for mounting or fastening rotating magnetic parts on to, or to, the rotor structures · CPC title

• H02K9/06

  with fans or impellers driven by the machine shaft · 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