Electric power tool

Patent metadata

Field	Value
Publication number	US-9837877-B2
Application number	US-201514696612-A
Country	US
Kind code	B2
Filing date	Apr 27, 2015
Priority date	May 9, 2014
Publication date	Dec 5, 2017
Grant date	Dec 5, 2017

Abstract

In an electric power tool, a stator of a motor is housed in a grip and the stator is located coaxial to the grip. An electric wire for the motor is passed through a ferrite core. Further, the ferrite core is located inside an outer peripheral surface of the stator in a radial direction.

First claim

What is claimed is:

1. An electric power tool comprising:
a grip being a portion of the electric power tool that is configured to be gripped by a user in order to operate the electric power tool;
a stator of a motor is housed in the grip and located coaxial to the grip, the stator comprising a stator core, wherein:
an electric wire for the motor is passed through a ferrite core; and
the ferrite core is located inside an outer peripheral surface of the stator in a radial direction.

2. The electric power tool of claim 1 , wherein the ferrite core is located such that an axis of the ferrite core is parallel to an axis of the motor or extends along a longitudinal direction of an inner wall surface of the grip.

3. The electric power tool of claim 1 , wherein:
the grip includes a first housing part in which the motor is housed and a second housing part in which an electrical component is housed; and
the ferrite core is located in the second housing part.

4. The electric power tool of claim 1 , wherein:
the electrical component includes a switch for starting or stopping the motor and a controller for controlling the motor; and
an electric wire via which the motor is electrically connected to at least one of the switch and the controller is passed through the ferrite core.

5. The electric power tool of claim 1 , wherein:
the motor includes a coil of the stator and a rotor winding that is electrically connected to the coil through a brush and a commutator; and
an electric wire via which the coil is connected to the brush is passed through the ferrite core.

6. The electric power tool of claim 1 , wherein:
an outer peripheral surface of the stator has substantially an elliptical shape that is vertically long and horizontally short when viewed from a direction perpendicular to an axis of the motor; and
the ferrite core is located such that the ferrite core partially overlaps with either one of an upper left, an upper right, a lower left, or a lower right corner of the stator in a radial direction.

7. The electric power tool of claim 6 , wherein:
a support part for supporting the ferrite core is located in the second housing part and further wherein the support part includes a right side vertical rib for supporting a right side of the ferrite core, a left side vertical rib for supporting a left side of the ferrite core, and a bottom plate for supporting a lower side or an upper side of the ferrite core at a base end of the right and left side vertical ribs; and
a protruding length of the left side vertical rib differs from that of the right side vertical rib when viewed from a direction perpendicular to an axis of the grip.

8. The electric power tool of claim 7 , wherein the right side vertical rib and the left side vertical rib ate located on an inner side of the outer peripheral surface of the stator in the radial direction when viewed from the direction perpendicular to the axis of the grip.

9. The electric power tool of claim 7 , wherein the protruding lengths of the left side vertical rib and the right side vertical rib are configured such that the left side vertical rib and the right side vertical rib extend to the outer peripheral surface of the stator.

10. The electric power tool of claim 7 , wherein the second housing part is covered with a tubular cover member.

11. The electric power tool of claim 10 , wherein a protrusion is located on an inner wall surface of the cover member such that the ferrite core supported by the support part of the second housing part is pressed by the protrusion from an opposite side of the bottom plate of the support part.

12. The electric power tool of claim 7 , wherein a hooked part is located in the right side vertical rib or the left side vertical rib to press the ferrite core from an opposite side of the bottom plate.

13. The electric power tool of claim 1 , wherein a capacitor is located between the switch and the controller to reduce noise.

Assignees

• Makita Corp

Inventors

• Hirata Yusuke

Classifications

• H02K7/145

  Hand-held machine tool · CPC title

• H02K23/66

  Structural association with auxiliary electric devices influencing the characteristic of, or controlling, the machine, e.g. with impedances or switches · CPC title

• B25F5/02

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

• H02K11/02 Primary

  for suppression of electromagnetic interference · CPC title