Power tool

Patent metadata

Field	Value
Publication number	US-12456897-B2
Application number	US-202217949687-A
Country	US
Kind code	B2
Filing date	Sep 21, 2022
Priority date	Nov 17, 2021
Publication date	Oct 28, 2025
Grant date	Oct 28, 2025

Abstract

A power tool is less likely to generate noise. A power tool includes a housing, a field fixed to the housing and including a field coil, an armature rotatable relative to the field and including a commutator, two brushes that come in contact with the commutator, and a brush holder unit holding the two brushes. The brush holder unit includes two contact rails electrically connectable to the field coil, two first terminals that each come in contact with either of the two contact rails, two second terminals each electrically connectable to a corresponding brush of the two brushes, and a choke coil located between at least one of the two first terminals and at least one of the two second terminals.

First claim

What is claimed is:

1. A power tool, comprising:
a housing;
a stator fixed to the housing, the stator including a field coil;
an armature rotatable relative to the stator, the armature including a commutator;
two brushes configured to come in contact with the commutator; and
a brush holder unit holding the two brushes, the brush holder unit including
a stationary housing,
two contact rails held by the stationary housing and electrically connectable to the field coil, each of the contact rails including
a rail portion being arc-shaped, and
a terminal portion intersecting with the rail portion,

a movable housing holding the two brushes and movable relative to the stationary housing,
two first terminals held by the movable housing, each of the two first terminals being configured to come in contact with either of the two contact rails in response to movement of the movable housing,
two second terminals held by the movable housing, each of the two second terminals being electrically connectable to a corresponding brush of the two brushes, and
a choke coil located between at least one of the two first terminals and at least one of the two second terminals,
wherein
each of the two contact rails includes an arch to come in contact with the either of the two first terminals,
the stationary housing includes a rectangular portion, and
the terminal portion includes a distal end received in the rectangular portion.

2. The power tool according to claim 1 , wherein
the brush holder unit includes a terminal holder holding one of the two first terminals and one of the two second terminals, and
the one of the two first terminals and the one of the two second terminals are held by the movable housing with the terminal holder in between.

3. The power tool according to claim 2 , wherein
the one of the two first terminals, the one of the two second terminals, and the terminal holder are integral with one another.

4. The power tool according to claim 3 , wherein
the terminal holder has a recess accommodating the choke coil.

5. The power tool according to claim 2 , wherein
the terminal holder has a recess accommodating the choke coil.

6. The power tool according to claim 2 , wherein
the terminal holder has a hole in a portion between the one of the two first terminals and the one of the two second terminals.

7. The power tool according to claim 1 , wherein
each of the two first terminals surrounds the either of the two contact rails.

8. The power tool according to claim 1 , wherein
each of the two contact rails includes an arch to come in contact with the either of the two first terminals.

9. The power tool according to claim 1 , wherein
each of the two first terminals includes a guide extending outward.

10. The power tool according to claim 1 , wherein
the two contact rails extend in a direction of a rotation axis of the armature.

11. The power tool according to claim 1 , wherein
the two contact rails comprise brass.

12. The power tool according to claim 1 , wherein
the terminal portion is electrically connectable to the field coil.

13. The power tool according to claim 1 , wherein
the terminal portion has the distal end not protruding from a distal end of the rectangular portion.

14. The power tool according to claim 1 , wherein
the movable housing has a flat or continuously curved surface, and the flat or continuously curved surface is located opposite to the stationary housing.

15. The power tool according to claim 1 , wherein
the stationary housing is attached to the housing.

16. The power tool according to claim 1 , wherein the housing includes
a motor housing holding the stator, and
an outer housing movable relative to the motor housing.

17. The power tool according to claim 16 , further comprising:
a flexible member located between the motor housing and the outer housing.

Assignees

• Makita Corp

Inventors

• Naito Akira

Classifications

• H02K13/06

  Resistive connections, e.g. by high-resistance chokes or by transistors · CPC title

• H02K5/148

  Slidably supported brushes · CPC title

• H02K9/06

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

• H02K5/207

  with openings in the casing specially adapted for ambient air · CPC title

• H02K13/04

  Connections between commutator segments and windings · CPC title