Brushless motor for a power tool

Patent metadata

Field	Value
Publication number	US-10205365-B2
Application number	US-201715474358-A
Country	US
Kind code	B2
Filing date	Mar 30, 2017
Priority date	Mar 30, 2016
Publication date	Feb 12, 2019
Grant date	Feb 12, 2019

Abstract

A brushless direct current motor for a power tool. The motor includes a stator assembly including a stator core having stator laminations with an annular portion and inwardly extending stator teeth. The motor also includes a rotor assembly including a rotor core having rotor laminations and defining a central aperture that receives an output shaft. The rotor assembly also includes a rotor end cap on a first side of the rotor core having a bearing holder and defining a channel, wherein the channel is open on a side of the rotor end cap facing the rotor core. The motor further includes a bearing provided in the bearing holder that couples the rotor end cap to the output shaft and a position sensor board assembly provided in the channel of the rotor end cap and configured to provide position information of the rotor core to a motor controller.

First claim

What is claimed is:

1. A power tool, comprising:
a housing;
a controller within the housing; and
a brushless motor within the housing and controlled by the controller, the brushless motor comprising:
a stator assembly including a stator core having stator laminations with an annular portion and inwardly extending stator teeth,
a rotor assembly including:
a rotor core having rotor laminations and defining a central aperture that receives an output shaft; and
a rotor end cap on a first side of the rotor core having a bearing holder and defining a channel, wherein the channel is open on a side of the rotor end cap facing the rotor core,

a bearing provided in the bearing holder that couples the rotor end cap to the output shaft, and
a position sensor board assembly provided in the channel of the rotor end cap and configured to provide position information of the rotor core to the controller.

2. The power tool of claim 1 , wherein the channel is annular and has a diameter that is less than an inner diameter of the stator assembly.

3. The power tool of claim 1 , wherein the position sensor board assembly includes a printed circuit board that is annular.

4. The power tool of claim 1 , wherein the stator assembly includes a first stator end cap and a second stator end cap and the stator laminations are provided between the first and second stator end caps, and wherein the stator assembly defines a stator envelope in an axial direction extending between axial ends of the first and second stator end caps, and wherein the position sensor board assembly is within the stator envelope.

5. The power tool of claim 4 , wherein the bearing is at least partially within the stator envelope.

6. The power tool of claim 4 , the rotor assembly further comprising:
a second rotor end cap provided on a second side of the rotor core; and
legs that extend from the second rotor end cap, between the stator teeth, to the rotor end cap to seal air gaps at an inner radial end of the stator core between the stator teeth.

7. The power tool of claim 6 , further comprising:
a gear case mounted to the second rotor end cap by fasteners;
a second bearing provided in a second bearing holder of the second rotor end cap, wherein the second bearing couples the second rotor end cap to the output shaft, and wherein the second bearing is at least partially within the stator envelope.

8. The power tool of claim 1 , the rotor assembly further comprising:
a connector portion providing a pathway that routes a connection between the position sensor board assembly and a sensor terminal block, wherein the pathway extends from the channel, between adjacent coils of the stator assembly, to the sensor terminal block.

9. A brushless direct current motor, comprising:
a stator assembly including a stator core having stator laminations with an annular portion and inwardly extending stator teeth,
a rotor assembly including:
a rotor core having rotor laminations and defining a central aperture that receives an output shaft; and
a rotor end cap on a first side of the rotor core having a bearing holder and defining a channel, wherein the channel is open on a side of the rotor end cap facing the rotor core,

a bearing provided in the bearing holder that couples the rotor end cap to the output shaft, and
a position sensor board assembly provided in the channel of the rotor end cap and configured to provide position information of the rotor core to a motor controller.

10. The brushless direct current motor of claim 9 , wherein the channel is annular and has a diameter that is less than an inner diameter of the stator assembly.

11. The brushless direct current motor of claim 9 , wherein the position sensor board assembly includes a printed circuit board that is annular.

12. The brushless direct current motor of claim 9 , wherein the stator assembly includes a first stator end cap and a second stator end cap and the stator laminations are provided between the first and second stator end caps, and wherein the stator assembly defines a stator envelope in an axial direction extending between axial ends of the first and second stator end caps, and wherein the position sensor board assembly is within the stator envelope.

13. The brushless direct current motor of claim 12 , wherein the bearing is at least partially within the stator envelope.

14. The brushless direct current motor of claim 12 , the rotor assembly further comprising:
a second rotor end cap provided on a second side of the rotor core; and
legs that extend from the second rotor end cap, between the stator teeth, to the rotor end cap to seal air gaps at an inner radial end of the stator core between the stator teeth.

15. The brushless direct current motor of claim 9 , the rotor assembly further comprising:
a connector portion providing a pathway that routes a connection between the position sensor board assembly and a sensor terminal block, wherein the pathway extends from the channel, between adjacent coils of the stator assembly, to the sensor terminal block.

16. A power tool, comprising:
a housing;
a controller within the housing; and
a brushless motor within the housing and controlled by the controller, the brushless motor including:
a stator assembly including a stator core having stator laminations with an annular portion and inwardly extending stator teeth, wherein the stator assembly defines a stator envelope in an axial direction extending between axial ends of stator end caps of the stator assembly,
a rotor assembly including:
a rotor core having rotor laminations and defining a central aperture that extends in the axial direction and that receives an output shaft,
a front rotor end cap provided on a first side of the rotor core, wherein the front rotor end cap has a front bearing holder, and
a rear rotor end cap provided on a second side of the rotor core, wherein the rear rotor end cap has a rear bearing holder,

a front bearing coupling the output shaft to the front rotor end cap,
a rear bearing coupling the output shaft to the rear rotor end cap, and
a position sensor board assembly including position sensors and configured to provide position information of the rotor core to the controller,
wherein the rotor assembly and the position sensor board assembly are provided at least partially within the stator envelope, and
wherein the front bearing and the rear bearing are provided at least partially within the stator envelope.

17. The power tool of claim 16 , wherein
the rear rotor end cap defines a channel and has a diameter that is less than an inner diameter of the stator assembly, and
the channel is open on a side of the rear rotor end cap facing the rotor core and the position sensor board assembly is provided in the channel.

18. The power tool of claim 17 , wherein the rear rotor end cap further comprises:
a connector portion providing a pathway that routes a connection between the position sensor board assembly and a sensor terminal block, wherein the pathway extends from the channel, between adjacent coils of the stator assembly, to the sensor terminal block.

19. The power tool of claim 16 , wherein the position sensor board assembly includes an annular board portion and legs extending radially outward from the annular board portion, and wherein at least one leg of the legs of the position sensor board assembly extends through a gap between adjacent stator end cap teeth of a first stator end cap of the stator end caps.

Assignees

• Milwaukee Electric Tool Corp

Inventors

• Beyerl Andrew T
• Boulanger Keith
• Huber Alex
• Elger William A
• Wackwitz Jeffrey M

Classifications

• H02K9/06

  with fans or impellers driven by the machine shaft · CPC title

• H02K7/086

  radially supporting the rotor around a fixed spindle; radially supporting the rotor directly (H02K7/09 takes precedence) · CPC title

• H02K5/15

  Mounting arrangements for bearing-shields or end plates · CPC title

• H02K11/215 Primary

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

• H02K11/21

  Devices for sensing speed or position, or actuated thereby (specially adapted for machines having non-mechanical commutating devices H02K29/06, H02K29/14) · CPC title