Power Tool

• US 20080265695A1
• Filed: 04/17/2008
• Published: 10/30/2008
• Est. Priority Date: 04/27/2007
• Status: Active Grant

• Current Assignee: Koki Holdings Co., Ltd.
• Original Assignee: Hitachi KOKI Company Limited (Koki Holdings Co., Ltd.)
• Inventors: Iwata, Kazutaka, Oomori, Katsuhiro, Komuro, Yoshihiro, Yoshida, Kenichirou
• Granted Patent: US 8,253,285 B2
• Time in Patent Office: Days
• US Class Current: 310/50
• CPC Class Codes: B25F 5/02 Construction of casings, bodies or handles B25F5/006, B25F5/008 take precedence
• CPC Class Codes: H02K 2211/03 Machines characterised by circuit boards, e.g. pcb
• CPC Class Codes: H02K 5/207 with openings in the casing specially adapted for ambient air
• CPC Class Codes: H02K 7/145 Hand-held machine tool
• CPC Class Codes: H02K 9/06 with fans or impellers driven by the machine shaft

Abstract

A power tool includes a housing, a brushless motor, and a cover member. The housing has an air intake hole and an air exhaust hole formed therein, the housing having an inner surface. The brushless motor has an outer surface disposed in the housing, a first endface near the air intake hole, and a second endface near the air exhaust hole. The cover member covers at least one of the first endface and the second endface for preventing dust from entering the brushless motor. The inner surface of the housing and outer surface of the brushless motor define a circulation path providing communication between the air intake hole and the air exhaust hole.

Claims

1. A power tool comprising:

a housing having an air intake hole and an air exhaust hole formed therein, the housing having an inner surface, a brushless motor having an outer surface disposed in the housing, a first endface near the air intake hole, and a second endface near the air exhaust hole;

a cover member covering at least one of the first endface and the second endface for preventing dust from entering the brushless motor; and

wherein the inner surface of the housing and outer surface of the brushless motor define a circulation path providing communication between the air intake hole and the air exhaust hole.

2. The power tool according to claim 1, wherein the brushless motor comprises:

a stator having;

a cylinder part having an inner peripheral surface, and an outer peripheral surface held by the inner surface of the housing; and

a plurality of teeth extending in an axial direction of the cylinder part and protruding radially inward from the inner peripheral surface;

a coil wound along the teeth;

a rotor concentric with the stator and rotatably disposed on a side of the inner peripheral surface of the stator; and

an insulating member having;

an annular part having the first endface forming a first annular opening and the second endface forming a second annular opening; and

a stator-covering part covering the teeth for insulating the teeth and the coil, the insulating member being held on the stator by winding the coil about the teeth covered by the stator-covering part; and

wherein the cover member covers at least one of the first annular opening and second annular opening.

3. The power tool according to claim 1, wherein the circulation path is defined between the inner surface of the housing and the outer peripheral surface of the stator.

4. The power tool according to claim 2, wherein the cover member comprises a circuit board held on the annular part and electrically connected to the coil and controlling the brushless motor.

5. The power tool according to claim 4, wherein the first endface has a female screw part,

wherein the power tool further comprises a male screw threadingly engaged with the female screw part to fix the circuit board to the first endface of the insulating member.

6. The power tool according to claim 4, wherein the circuit board has a detecting element detecting a rotational position of the rotor and facing the first endface.

7. The power tool according to claim 4, wherein the coil comprises:

a wound part wound about the teeth; and

a beginning portion formed continuously with the wound part and connecting the wound part to the circuit board, and having a bend part formed in a bent shape to avoid interference with the wound part.

8. The power tool according to claim 2, wherein the brushless motor has a drive shaft supporting the rotor and rotatable together with the rotor;

wherein the power tool further comprises a fan fixed to the drive shaft at a position near the air exhaust hole; and

wherein the cover member is disposed between the fan and the second endface and covers the second endface.

9. The power tool according to claim 8, wherein the cover member is formed with a notch that allows the cover member to straddle the drive shaft of the brushless motor.

10. The power tool according to claim 9, wherein the housing comprises a shielding wall at a position facing the notch for shielding the notch.

11. The power tool according to claim 8, wherein the cover member is formed with a through-hole that allows the drive shaft to pass therethrough.

12. The power tool according to claim 8, further comprising a rib provided on at least one of the housing and the cover member and positioned in the circulation path for fixing the cover member to the housing.

13. The power tool according to claim 12, wherein the rib has a deforming part that deforms upon fixing the cover to the housing.

14. The power tool according to claim 12, wherein the rib has a tapered part guiding the cover to a prescribed position in the housing.

15. The power tool according to claim 8, wherein the cover member has one of a recessed part and a protruding part, and the insulating member has a complementary one of a projection part and a depression part for engaging with one of the recessed part and protruding part.

16. The power tool according to claim 2, further comprising another cover member covering the first endface, and

wherein the cover member covers the second endface.

17. The power tool according to claim 16, wherein the another cover member comprises a circuit board electrically connected to the coil and controlling the brushless motor.

18. A power tool comprising:

a housing having an inner surface;

a brushless motor supported by the housing, the brushless motor comprising;

a stator having;

a cylinder part having an inner peripheral surface, and an outer peripheral surface held by the inner surface of the housing; and

a plurality of teeth extending in an axial direction of the cylinder part and protruding radially inward from the inner peripheral surface;

a coil having;

a wound portion wound along the teeth; and

a beginning portion connecting the wound portion to the circuit board and being formed in a bent shape so as not to interfere with the wound portion;

a rotor concentric with the stator and rotatably disposed on a side of the inner peripheral surface of the stator; and

an insulating member having;

an annular part having an axial end of the stator; and

a stator-covering part covering the teeth for insulating the teeth and the coil, the insulating member being held on the stator by winding the coil about the teeth covered by the stator-covering part; and

a circuit board held on the annular part and electrically connected to the coil and controlling the brushless motor.