Power tool

Patent metadata

Field	Value
Publication number	US-11095174-B2
Application number	US-202016998043-A
Country	US
Kind code	B2
Filing date	Aug 20, 2020
Priority date	Jun 12, 2017
Publication date	Aug 17, 2021
Grant date	Aug 17, 2021

Abstract

A rotor has reduced weight. A hammer drill includes a motor including a stator and a rotor rotatable relative to the stator. The rotor includes a rotor core having a first space, and a permanent magnet fixed on the rotor core.

First claim

What is claimed is:

1. A power tool, comprising:
a stator including
a stator core,
an insulator held on the stator core, and
a coil wound at the insulator;

a rotor rotatably arranged inside the stator, the rotor including
a rotational shaft,
a rotor core,
a plurality of permanent magnets,
a first sleeve on a first side of the rotor core,
a second sleeve on a second side of the rotor core, and
a resin fixing the rotational shaft, the rotor core, the plurality of permanent magnets, the first sleeve and the second sleeve together; and

an output unit driven by the rotor,
wherein the resin is between the rotational shaft and the first sleeve, and between the rotational shaft and the second sleeve.

2. The power tool according to claim 1 , wherein
the rotational shaft has an outer peripheral surface having a spiral groove,
the rotor core has a non-circular shaped central hole, and
the resin is disposed between the spiral groove and the central hole.

3. The power tool according to claim 2 , wherein
the rotor core has a plurality of through-holes,
each of the plurality of permanent magnets is disposed in each of the plurality of through-holes, and
the resin is disposed between the through-hole and the permanent magnet.

4. The power tool according to claim 2 , wherein
the resin includes a first resin portion and a second resin portion,
the first sleeve is between the rotor core and the first resin portion in an axial direction of the rotational shaft, and
the second sleeve is between the rotor core and the second resin portion in the axial direction of the rotational shaft.

5. The power tool according to claim 2 , wherein
the resin includes a third resin portion between the first and second sleeves and the permanent magnet in an axial direction of the rotational shaft.

6. The power tool according to claim 1 , wherein
the rotor core has a plurality of through-holes,
each of the plurality of permanent magnets is disposed in each of the plurality of through-holes, and
the resin is disposed between the through-hole and the permanent magnet.

7. The power tool according to claim 6 , wherein
the resin includes a first resin portion and a second resin portion,
the first sleeve is between the rotor core and the first resin portion in an axial direction of the rotational shaft, and
the second sleeve is between the rotor core and the second resin portion in the axial direction of the rotational shaft.

8. The power tool according to claim 6 , wherein
the resin includes a third resin portion between the first and second sleeves and the permanent magnet in an axial direction of the rotational shaft.

9. The power tool according to claim 1 , wherein
the resin includes a first resin portion and a second resin portion,
the first sleeve is between the rotor core and the first resin portion in an axial direction of the rotational shaft, and
the second sleeve is between the rotor core and the second resin portion in the axial direction of the rotational shaft.

10. The power tool according to claim 9 , wherein
the resin includes a third resin portion disposed between the sleeve and the permanent magnet in an axial direction of the rotational shaft.

11. The power tool according to claim 1 , wherein
the resin includes a third resin portion between the first and second sleeves and the permanent magnet in an axial direction of the rotational shaft.

12. The power tool according to claim 1 , wherein
the first sleeve has a larger diameter than the second sleeve.

13. The power tool according to claim 12 , wherein
the second sleeve is arranged inside the permanent magnet in a radial direction.

14. A power tool, comprising:
a stator including
a stator core,
an insulator held on the stator core, and
a coil wound at the insulator;

a rotor rotatably arranged inside the stator, the rotor including
a rotational shaft,
a rotor core having
a central hole, and
a plurality of through-holes arranged around the central hole,

a plurality of permanent magnets each disposed in each of the plurality of through-holes,
a first sleeve on an upper side of the rotor core,
a second sleeve on a lower side of the rotor core,
a first resin portion between the rotational shaft and each of the rotor core and the first and second sleeves around an outer surface of the rotation shaft,
a second resin portion between the first sleeve and the rotor core, the second resin portion being continuous with the first resin portion,
a fourth resin portion around the permanent magnet inside the through-hole, the fourth resin portion being continuous with the second resin portion,
a fifth resin portion below the second sleeve, the fifth resin portion being continuous with the first resin portion; and

an output unit driven by the rotor.

15. The power tool according to claim 14 , wherein
the rotor further includes a third resin portion above the first sleeve, the third resin portion being continuous with the first resin portion.

16. The power tool according to claim 14 , wherein
the second resin portion is disk-shaped.

17. The power tool according to claim 14 , wherein
the third resin portion is disk-shaped.

18. A power tool, comprising:
a stator including
a stator core,
an insulator held on the stator core, and
a coil wound at the insulator;

a rotor rotatably arranged inside the stator, the rotor including
a rotational shaft,
a rotor core,
a plurality of permanent magnets,
a first sleeve on a first side of the rotor core,
a second sleeve on a second side of the rotor core,
a resin portion between the rotational shaft and each of the rotor core and the first and second sleeves around an outer surface of the rotational shaft, the resin portion extending beyond the first sleeve along the rotor core toward the first side, the resin portion extending beyond the second sleeve along the rotor core toward the second side; and

an output unit driven by the rotor.

Assignees

• Makita Corp

Inventors

• INUZUKA Junya

Classifications

• B25F5/02

  Construction of casings, bodies or handles {(B25F5/006, B25F5/008 take precedence)} · CPC title

• B25D2211/068

  Crank-actuated impulse-driving mechanisms · CPC title

• B25D11/12

  comprising a crank mechanism · CPC title

• B25D2250/265

  Trigger mechanism in handle · CPC title

• B25D16/00

  Portable percussive machines with superimposed rotation {, the rotational movement of the output shaft of a motor being modified to generate axial impacts on the tool bit (combined percussion and rotary drilling adapted for earth drilling E21B6/00)} · CPC title