Power tool

Patent metadata

Field	Value
Publication number	US-2016226339-A1
Application number	US-201615002652-A
Country	US
Kind code	A1
Filing date	Jan 21, 2016
Priority date	Feb 4, 2015
Publication date	Aug 4, 2016
Grant date	—

Abstract

A power tool ( 1 ) includes a brushless motor ( 8 ) having a stator ( 9 ) and a rotor ( 10 ). The stator ( 9 ) includes: a tubular stator core ( 60 ); front and rear insulators ( 61, 62 ) fixed to the stator core; and coils ( 64 ), which are wound around a plurality of teeth ( 63 ) on the stator core. The rotor ( 10 ) includes: a rotor core ( 67 ) disposed within the stator; a rotary shaft ( 11 ) fixed to the rotor core; and one or more permanent magnets ( 68 ) fixed to the rotor core. A sensor-circuit board ( 65 ) detects the position(s) of the permanent magnet(s) and is fixed to the stator. One or more notched parts ( 91 ) is/are formed, in an outer circumference of the sensor-circuit board, between circumferentially-adjacent teeth in an axial direction of the stator. The notch part(s) allow(s) air for cooling the brushless motor to pass more easily through the interior of the stator.

First claim

1 . A power tool having a motor, comprising:
a stator comprising: a tubular stator core; one or more electrically insulating members fixed to the stator core; and coils, which are wound around a plurality of teeth that protrude from an inner side of the stator core; a rotor comprising: a rotor core disposed on an inner side of the stator; a rotary shaft fixed to the rotor core; and one or more permanent magnets fixed to the rotor core; and a sensor-circuit board configured to detect position(s) of the permanent magnet(s), the sensor-circuit board being fixed to the stator;
wherein,
at least one notched part is formed, in an outer circumference of the sensor-circuit board, such that it is located between two of the teeth in an axial direction of the stator.

2 . The power tool according to claim 1 , wherein
the stator and the sensor-circuit board are fixed together via fixing parts at at least two positions located along a circumferential direction of the stator; and the at least one notched part is formed between the fixing parts.

3 . The power tool according to claim 1 , wherein
the at least one notched part comprises at least two notched parts that are respectively formed at at least two locations along a circumferential direction of the stator; and the sensor-circuit board comprises a connection part configured to hold at least one lead wire that outputs a detection signal, the connection part being disposed between the at least two notched parts.

4 . The power tool according to claim 1 , wherein
the stator comprises at least two terminals respectively connected to at least two of the coils; the at least notched part comprises at least two notched parts that are respectively formed at at least two locations along a circumferential direction of the stator; and the terminals are respectively disposed in the at least two notched parts of the sensor-circuit board.

5 . The power tool according to claim 1 , wherein
six of the coils are provided; the at least one notched part comprises six notched parts that are respectively formed at six locations along a circumferential direction of the sensor-circuit board; and each of the six notched parts respectively exposes one of the six coils in the axial direction of the stator.

6 . The power tool according to claim 5 , wherein
the stator is fixed to the sensor-circuit board via at least three fixing parts respectively located at three positions along the circumferential direction of the sensor-circuit board.

7 . The power tool according to claim 6 , wherein
the stator comprises three terminals respectively connected to three pairs of the coils; and the three terminals are respectively disposed in three of the notched parts of the sensor-circuit board that are adjacent to each other in the circumferential direction of the sensor-circuit board.

8 . The power tool according to claim 7 , wherein
the sensor-circuit board comprises a connection part configured to hold at least one lead wire that outputs a detection signal, the connection part being disposed between two of the notched parts.

9 . The power tool according to claim 8 , wherein
the three terminals are respectively connected to power-supply lines for the three pairs of the coils; the one or more electrically insulating members comprise first and second electrically insulating members; the three terminals are provided on the first electrically insulating member, and the sensor-circuit board is screw fastened onto the first electrically insulating member.

10 . The power tool according to claim 9 , wherein
a groove is provided on an outer circumference of the stator core and extends along an axial direction of the stator; first and second mating pieces are respectively formed, in an integral manner with the first and second electrically insulating members; and the first and second mating pieces both mate with the groove.

11 . A power tool having a motor, comprising:
a stator comprising: a tubular stator core; a first electrically insulating member and a second electrically insulating member, which are respectively fixed to front and rear end surfaces of the stator core; and coils, which are wound around a plurality of teeth that protrude from an inner side of the stator core; a rotor comprising: a rotor core disposed on an inner side of the stator; a rotary shaft fixed to the rotor core; and one or more permanent magnets fixed to the rotor core; and a sensor-circuit board configured to detect position(s) of the permanent magnet(s), the sensor-circuit board being fixed to an outer-circumference side of the first electrically insulating member;
wherein,
terminals are respectively connected to the coils and to power-supply lines for the coils, the terminals being provided on the first electrically insulating member.

12 . The power tool according to claim 11 , wherein
the sensor-circuit board is screw fastened onto the first electrically insulating member.

13 . The power tool according to claim 11 , wherein
three of the terminals are provided; and the coils are delta connected.

14 . The power tool according to claim 11 , wherein
the terminals are respectively disposed between circumferentially-adjacent pairs of the teeth.

15 . The power tool according to claim 11 , wherein
two of the terminals are provided; and the sensor-circuit board comprises a connection part configured to hold a lead wire that outputs a detection signal, the connection part being disposed between the two terminals.

16 . The power tool according to claim 15 , wherein
the terminals are respectively disposed between circumferentially-adjacent pairs of the teeth.

17 . The power tool according to claim 16 , wherein
the sensor-circuit board is screw fastened onto the first electrically insulating member.

18 . The power tool according to claim 17 , wherein
three of the terminals are provided; and the coils are delta connected.

19 . A power tool having a motor, comprising:
a stator comprising: a tubular stator core; electrically insulating members respectively fixed to front and rear end surfaces of the stator core; and coils, which are wound around a plurality of teeth that protrude from an inner side of the stator core; a rotor comprising: a rotor core disposed on an inner side of the stator; a rotary shaft fixed to the rotor core; and one or more permanent magnets fixed to the rotor core; and a sensor-circuit board configured to detect position(s) of the permanent magnet(s), the sensor-circuit board being fixed to the stator;
wherein,
a groove is provided on an outer circumference of the stator core and extends along an axial direction of the stator; and
mating pieces, which mate with the groove, are respectively formed integrally with the electrically insulating members.

20 . The power tool according to claim 19 , wherein
the groove comprises a plurality of grooves provided on the outer circumference of the stator core and each groove extends along the axial direction of the stator; and a plurality of mating pieces are integrally formed on each of the electrically insulating members, the plurality of mating pieces respectively engaging in the plurality of grooves.

Assignees

• Makita Corp

Inventors

• Niwa Akira
• Kouda Kei

Classifications

• H02K1/27

  Rotor cores with permanent magnets · CPC title

• H02K9/02

  by ambient air flowing through the machine · CPC title

• H02K7/145 Primary

  Hand-held machine tool · CPC title

• H02K5/08

  Insulating casings · CPC title

• H02K5/225

  Terminal boxes or connection arrangements (specially adapted for submersible motors H02K5/132) · CPC title