POWER TOOL

• US 20150069864A1
• Filed: 09/09/2014
• Published: 03/12/2015
• Est. Priority Date: 09/11/2013
• Status: Active Grant

• Current Assignee: Makita Corporation
• Original Assignee: Makita Corporation
• Inventors: Nagahama, Tatsuya, lnuzuka, Junya, Momose, Takashi
• Granted Patent: US 9,948,162 B2
• Time in Patent Office: Days
• US Class Current: 310/50
• CPC Class Codes: B25F 5/00 Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
• CPC Class Codes: B25F 5/008 Cooling means
• CPC Class Codes: B25F 5/02 Construction of casings, bodies or handles B25F5/006, B25F5/008 take precedence
• CPC Class Codes: H02K 11/215 Magnetic effect devices, e.g. Hall-effect or magneto-resistive elements
• CPC Class Codes: H02K 11/27 Devices for sensing current, or actuated thereby overcurrent protection responsive to temperature of the machines or parts thereof, e.g. windings, H02K11/25
• CPC Class Codes: H02K 2203/03 Machines characterised by the wiring boards, i.e. printed circuit boards or similar structures for connecting the winding terminations
• CPC Class Codes: H02K 2203/09 Machines characterised by wiring elements other than wires, e.g. bus rings, for connecting the winding terminations
• CPC Class Codes: H02K 29/08 using magnetic effect devices, e.g. Hall-plates, magneto-resistors H02K29/12 takes precedence
• CPC Class Codes: H02K 3/28 Layout of windings or of connections between windings windings for pole-changing H02K17/06, H02K17/14, H02K19/12, H02K19/32
• CPC Class Codes: H02K 3/522 for generally annular cores with salient poles
• CPC Class Codes: H02K 5/04 Casings or enclosures characterised by the shape, form or construction thereof
• CPC Class Codes: H02K 5/225 Terminal boxes or connection arrangements specially adapted for submersible motors H02K5/132
• CPC Class Codes: H02K 7/116 with gears
• CPC Class Codes: H02K 7/145 Hand-held machine tool

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 (23a) respectively electrically connect circumferentially-adjacent pairs of the coils (23). A short circuiting device (25) short circuits respective pairs of windings (23a) that are located diagonally or diametrically across from one another.

Claims

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 through the front and rear insulators,

winding wires respectively electrically connecting circumferentially-adjacent pairs of the coils and

a short circuiting means that short circuits respective pairs of the winding wires that are positioned diagonally across from one another.

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 short circuiting means comprises:

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.

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 means 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 wires.

6. The power tool according to claim 5, wherein the short circuiting means 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 1, wherein the short circuiting means comprises lead wires that respectively electrically interconnect the pairs of winding wires that are positioned diagonally across from one another.

9. The power tool according to claim 1, further comprising:

a sensor circuit board provided between the short circuiting means 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.

10. The power tool according to claim 9, 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 means 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 fusing terminals that are circumferentially-arranged along an outer diameter thereof, and

the fusing terminals respectively connect the winding wires to the short circuiting means.

13. The power tool according to claim 12, wherein:

the fusing terminals each comprise a folded-over metal strip and

the winding wires are respectively sandwiched between first and second edges of the fusing terminals.

14. The power tool according to claim 13, wherein the fusing terminals are respectively electrically connected to corresponding short circuiting pieces of the short circuiting means, 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 means 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, further comprising:

a sensor circuit board provided between the short circuiting means 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.

17. The power tool according to claim 16, wherein the short circuiting means comprises:

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 means 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.

18. The power tool according to claim 17, wherein:

the short circuiting means 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.

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,

a plurality of coils respectively wound on the stator such that the coils are wound through the front and rear insulators, and

a housing that houses the motor and is formed by combining a pair of half housings,

wherein the stator includes positioning parts that engage with respective inner surfaces of the half housings, the positioning parts preferably being provided on one of the first and second insulator.

20. 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,

a plurality of coils respectively wound on the stator such that the coils are wound through the front and rear insulators and

an integral tubular housing that houses the motor,

wherein the stator is provided with at least one positioning part that engages with an inner surface of the tubular housing, the at least one positioning part preferably being provided on one of the first and second insulator.