Impact tool

1 . An impact tool, comprising:

a brushless motor including a stator including a stator core, an insulating member and coils, and a rotor that is rotatable with respect to the stator, an axis of rotation of the rotor extending in a front-rear direction of the impact tool;

a first bearing rotatably supporting the rotor;

a motor housing that houses the brushless motor;

a hammer case that is tubular and has at least one recess;

a disk-shaped bearing retainer having a front part that is coupled to a rear end of the hammer case and a rear part that holds the first bearing;

a grip housing disposed downward of the motor housing;

a battery pack disposed downward of the grip housing;

a planetary gear mechanism disposed frontward of the brushless motor, the planetary gear mechanism including an internal gear having at least one protrusion that extends into the at least one recess in the hammer case, and planetary gears that mesh with the internal gear;

a spindle disposed frontward of the brushless motor;

a hammer disposed around an outer circumference of the spindle; and

an anvil configured to be struck rotationally by the hammer;

wherein:

the planetary gear mechanism and the hammer are housed within the hammer case;

the bearing retainer is disposed inside the motor housing and the hammer case; and

at least the rear part of the bearing retainer is disposed inside the insulating member, the rear part of the bearing retainer having an external diameter that is smaller than an inner diameter of the insulating member.

2 . The impact tool according to claim 1 , wherein the front part of the bearing retainer holds a second bearing that rotatably supports the spindle.

3 . The impact tool according to claim 1 , wherein a plurality of hollow parts, which are arrayed in a circumferential direction, and a plurality of ribs, which extend radially and provide partitions between the hollow parts, are formed on the bearing retainer radially outward of the first bearing.

4 . The impact tool according to claim 1 , wherein:

a hollow part is formed in a central part of the bearing retainer in the front-rear direction, and

an inward protruding rib that engages with the hollow part is disposed on an inner surface of the motor housing.

5 . The impact tool according to claim 1 , wherein:

the at least one protrusion comprises a plurality of circumferentially spaced-apart protrusions on the internal gear;

the at least one recess comprises a plurality of circumferentially spaced-apart recesses in the hammer case; and

the plurality of circumferentially spaced-apart protrusions respectively extend into the plurality of circumferentially spaced-apart recesses.

6 . The impact tool according to claim 5 , wherein there are four of the circumferentially spaced-apart protrusions and four of the circumferentially spaced-apart recesses.

7 . The impact tool according to claim 1 , wherein overlapping portions of the motor housing and the hammer case radially surround the bearing retainer.

8 . The impact tool according to claim 1 , wherein the bearing retainer is screw-fastened to the hammer case.

9 . An impact tool, comprising:

a brushless motor including i) a stator having a stator core and an insulating member and a coil and ii) a rotor that is rotatable with respect to the stator and disposed inside the stator, an axis of rotation of the rotor extending in a front-rear direction of the impact tool;

a motor housing that houses the brushless motor and includes a left motor housing, a right motor housing, and a rear motor housing, the left motor housing, the right motor housing and the rear motor housing are fixed by a plurality of screws;

a fan disposed between the rotor and the rear motor housing;

a grip housing disposed downward of the motor housing;

a battery pack disposed below the grip housing;

a hammer case having a recess;

a planetary gear mechanism disposed frontward of the brushless motor and including an internal gear and planetary gears meshed with the internal gear, the internal gear having a protrusion extending into the recess of the hammer case;

a spindle disposed frontward of the brushless motor;

a hammer disposed around an outer circumference of the spindle inside the hammer case;

an anvil configured to be struck rotationally by the hammer;

a first bearing that supports the rotor; and

a bearing retainer screw-fastened to the hammer case and holding the first bearing, the bearing retainer and the insulating member overlapping in the front-rear direction.

10 . The impact tool according to claim 9 , wherein the rotor includes a plurality of tubular permanent magnets having polarities that alternate in a circumferential direction.

11 . The impact tool according to claim 9 , wherein the bearing retainer is formed in a disc shape, a front part of the bearing retainer is screw-fastened to the hammer case, and a rear part of the bearing retainer holds the first bearing that supports the rotor.

12 . The impact tool according to claim 11 , further comprising:

a sensor board configured to detect a rotational position of the rotor and fixed to the insulating member from the front by a plurality of screws,

wherein the rear part of the bearing retainer is positioned radially inward of the screws when viewed in the front-rear direction.

13 . The impact tool according to claim 11 , wherein the front part of the bearing retainer holds a second bearing that rotatably supports the spindle.

14 . The impact tool according to claim 11 , wherein a plurality of hollow parts, which are arrayed in a circumferential direction, and a plurality of ribs, which extend radially and provide partitions between the hollow parts, are formed on the bearing retainer radially outward of the first bearing.

15 . The impact tool according to claim 11 , wherein:

a hollow part is formed in a central part of the bearing retainer in the front-rear direction, and

an inward protruding rib that engages with the hollow part is disposed on an inner surface of the motor housing.

16 . An impact tool, comprising:

a brushless motor including i) a stator having a stator core and an insulating member disposed frontward of the stator core and a coil and ii) a rotor that is rotatable with respect to the stator and disposed inside the stator, an axis of rotation of the rotor extending in a front-rear direction of the impact tool;

a motor housing that houses the brushless motor and includes a left motor housing, a right motor housing, a rear motor housing having at least one right-side exhaust port and at least one left-side exhaust port, and a plurality of screws that fixedly interconnect the left motor housing, the right motor housing, and the rear motor housing;

a fan disposed between the rotor and the rear motor housing;

a grip housing disposed downward of the motor housing;

a battery pack disposed below the grip housing;

a hammer case having a first recess;

a planetary gear mechanism disposed frontward of the brushless motor and including an internal gear and planetary gears meshed with the internal gear, the internal gear having a first protrusion extending into the first recess of the hammer case;

a spindle disposed frontward of the brushless motor;

a hammer disposed around an outer circumference of the spindle inside the hammer case;

an anvil configured to be struck rotationally by the hammer;

a bearing that supports the rotor; and

a bearing retainer coupled to the hammer case and holding the bearing,

wherein a front part of the insulating member and a rear part of the bearing retainer overlap in the front-rear direction.

17 . The impact tool according to claim 16 , wherein the bearing retainer is screw-fastened to the hammer case.

18 . The impact tool according to claim 16 , wherein:

the bearing retainer is formed in a disc shape, a front part of the bearing retainer is coupled to a rear end of the hammer case, and a rear part of the bearing retainer holds the bearing, and

the rear part of the bearing retainer has an external diameter that is smaller than an inner diameter of the insulating member.

19 . The impact tool according to claim 16 , wherein:

the internal gear further has a second protrusion that is spaced apart from the first protrusion in a circumferential direction around the internal gear;

the hammer case further has a second recess that is spaced apart from the first recess in a circumferential direction around the hammer case; and

the second protrusion extends into the second recess.