Power tool

Patent metadata

Field	Value
Publication number	US-9948162-B2
Application number	US-201414481237-A
Country	US
Kind code	B2
Filing date	Sep 9, 2014
Priority date	Sep 11, 2013
Publication date	Apr 17, 2018
Grant date	Apr 17, 2018

Abstract

A power tool ( 1; 90 ) includes a motor ( 17 ) having a stator ( 18 ) and a rotor ( 19 ). The stator ( 18 ) includes front and rear insulators ( 21, 22 ) respectively disposed forward and rearward of a stator core ( 20 ) in an axial direction thereof. At least six coils ( 23 ) are respectively wound on the stator ( 18 ) such that the coils ( 23 ) are wound through the front and rear insulators ( 21, 22 ). Winding wires ( 23 a ) respectively electrically connect circumferentially-adjacent pairs of the coils ( 23 ). A short circuiting device ( 25 ) short circuits respective pairs of windings ( 23 a ) that are located diagonally or diametrically across from one another.

First claim

We claim:

1. A power tool comprising:
a motor having a stator and a rotor, the stator including front and rear insulators respectively disposed forward and rearward of a stator core in an axial direction thereof,
at least six coils respectively wound on the stator such that the coils are wound on the front and rear insulators,
winding wire segments respectively electrically connecting circumferentially-adjacent pairs of the coils,
a short circuiting element comprising electrically conductive elements that respectively connect pairs of the winding wire segments that are positioned diagonally across from one another, and
a sensor circuit board provided between the short circuiting element and one of the front or rear insulator, the sensor circuit board having at least one rotation detection device for detecting positions of permanent magnets provided on the rotor or on a centrifugal fan.

2. The power tool according to claim 1 , wherein all of the coils are wound with a single continuous winding wire.

3. The power tool according to claim 1 , wherein the electrically conductive elements comprise:
a plurality of sheet metal elements that respectively electrically interconnect the pairs of winding wire segments that are positioned diagonally across from one another, and
an insulation part, which is made of resin and retains the sheet metal elements.

4. The power tool according to claim 3 , wherein the sheet metal elements each have a semi-circular shape in a radial direction of the short circuiting element and are embedded in the resin of the insulating part so to be electrically isolated from each other.

5. The power tool according to claim 4 , wherein the sheet metal elements each have two short circuiting pieces that are disposed radially opposite of each other and are respectively aligned with diagonally-opposite winding wire segments.

6. The power tool according to claim 5 , wherein the short circuiting element has three sheet metal elements that are respectively electrically connected to U-phase, V-phase, and W-phase power supply lines.

7. The power tool according to claim 6 , wherein all of the coils are wound with a single continuous winding wire.

8. The power tool according to claim 3 , wherein the insulation part further comprises parallel guide ribs that integrally extend perpendicularly from a surface of the insulation part.

9. The power tool according to claim 1 , wherein the short circuiting element comprises wires that respectively electrically interconnect the pairs of winding wire segments that are positioned diagonally across from one another.

10. The power tool according to claim 1 , wherein the sensor circuit board is configured to be mounted in more than one rotational orientation.

11. The power tool according to claim 1 , wherein:
the short circuiting element is annular and has an outer diameter that is at least substantially the same as the outer diameter of the stator core,
the front insulator is annular and has an outer diameter that is at least substantially the same as the outer diameter of the stator core,
the rear insulator is annular and has an outer diameter that is at least substantially the same as the outer diameter of the stator core, and
protruding parts radially-inwardly project from an inner circumferential surface of each of the front and rear insulators in series in the circumferential direction, the coils being respectively wrapped around corresponding protruding parts.

12. The power tool according to claim 1 , wherein:
one of the front and the rear insulator retains a plurality of thermally crimped terminals that are circumferentially-arranged along an outer diameter thereof, and
the thermally crimped terminals respectively connect the winding wire segments to the short circuiting element.

13. The power tool according to claim 12 , wherein:
the thermally crimped terminals each comprise a folded-over metal strip and
the winding wire segments are respectively sandwiched between first and second edges of the fusing terminals.

14. The power tool according to claim 13 , wherein the thermally crimped terminals are respectively electrically connected to corresponding short circuiting pieces of the short circuiting element, the short circuiting pieces each extending in a radial direction of the stator core.

15. The power tool according to claim 14 , wherein:
the short circuiting element is annular and has an outer diameter that is at least substantially the same as the outer diameter of the stator core,
the front insulator is annular and has an outer diameter that is at least substantially the same as the outer diameter of the stator core,
the rear insulator is annular and has an outer diameter that is at least substantially the same as the outer diameter of the stator core, and
protruding parts radially-inwardly project from an inner circumferential surface of each of the front and rear insulators in series in the circumferential direction, the coils being respectively wrapped around corresponding protruding parts.

16. The power tool according to claim 15 , wherein the electrically conductive elements comprise:
a plurality of sheet metal elements that respectively electrically interconnect the pairs of winding wires that are positioned diagonally across from one another, and
an insulation part, which is made of resin and retains the sheet metal elements,
wherein the sheet metal elements each have a semi-circular shape in a radial direction of the short circuiting element and are embedded in the resin of the insulating part so to be electrically isolated from each other and
the sheet metal elements each have two short circuiting pieces that are disposed radially opposite of each other and are respectively aligned with diagonally-opposite winding wires.

17. The power tool according to claim 16 , wherein:
the short circuiting element has three sheet metal elements that are respectively electrically connected to U-phase, V-phase, and W-phase power supply lines, and
all of the coils are wound with a single continuous winding wire.

18. The power tool according to claim 1 , wherein the short circuiting element and the sensor circuit board are fastened to the front or the rear insulator by at least one common screw.

19. A power tool comprising:
a motor having a stator and a rotor, the stator including front and rear insulators respectively disposed forward and rearward of a stator core in an axial direction thereof,
at least six coils respectively wound on the stator such that the coils are wound on the front and rear insulators,
winding wire segments respectively electrically connecting circumferentially-adjacent pairs of the coils,
a short circuiting means that short circuits respective pairs of the winding wire segments that are positioned diagonally across from one another, the short circuiting means comprising a number of electrically conductive elements corresponding to the number of pairs of the winding wire segments that are positioned diagonally across from one another, each of the electrically conductive elements having a pair of short circuiting pieces,
wherein radially outer portions of the short circuiting pieces each have a slit defined therein.

Assignees

• Makita Corp

Inventors

• Nagahama Tatsuya
• INUZUKA Junya
• Momose Takashi

Classifications

• H02K11/215

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

• H02K7/116

  with gears · CPC title

• H02K11/27

  Devices for sensing current, or actuated thereby (overcurrent protection responsive to temperature of the machines or parts thereof, e.g. windings, H02K11/25) · CPC title

• H02K2203/09

  Machines characterised by wiring elements other than wires, e.g. bus rings, for connecting the winding terminations · CPC title

• H02K29/08

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