Electric power tools

• US 20100163266A1
• Filed: 12/24/2009
• Published: 07/01/2010
• Est. Priority Date: 12/26/2008
• Status: Abandoned Application

• Current Assignee: Makita Corporation
• Original Assignee: Makita Corporation
• Inventors: Omura, Motohiro, Kusakawa, Takuya, Matsunaga, Yutaka
• Application Number:
  US12/654,598
• Publication Number:
  US 20100163266A1
• Time in Patent Office: Days
• US Class Current: 173/217
• CPC Class Codes: B25F 5/02 Construction of casings, bodies or handles B25F5/006, B25F5/008 take precedence
• CPC Class Codes: H02K 11/33 Drive circuits, e.g. power electronics H02K11/38 takes precedence

Abstract

One aspect according to the present invention includes an electric power tool, in which a capacitor is positioned closer to a motor control circuit than a switch electrically connected to the motor control circuit.

Claims

1. An electric power tool, comprising:

a housing body part capable of housing a brushless DC motor as a driving source;

a grip part formed to protrude from a lateral part of the housing body part;

a switch part provided in such a position that allows a user to engage a finger of the user with the switch part while the user holds the grip part;

a battery capable of supplying a power to the blushless DC motor;

a three-phase bridge circuit configured to control the blushless DC motor and including switching devices; and

a capacitor connected in parallel with the three-phase bridge circuit;

wherein the three-phase bridge circuit is disposed proximal to the brushless DC motor within the housing body part, and the capacitor is disposed at a position proximal to the switch part.

2. The electric power tool according to claim 1, further comprising electric conductors electrically connecting between the capacitor and the three-phase bridge circuit and configured to connect the capacitor and the three-phase bridge circuit at the shortest distance.

3. The electric power tool according to claim 1, wherein the switch part is positioned on a front side of the housing body part, the three-phase bridge circuit is positioned on a rear side of the brushless DC motor, and the capacitor is mounted on an electrical circuit board of the switch part.

4. The electric power tool according to claim 1, wherein the switch part is positioned on a front side of the housing body part, the three-phase bridge circuit is positioned on a rear side of the brushless DC motor, and the capacitor is positioned at a boundary region between the housing body part and the grip part.

5. The electric power tool according to claim 1, wherein the switch part is positioned on a front side of the housing body part, the three-phase bridge is positioned on a rear side of the brushless DC motor, and the capacitor is mounted on an electrical circuit board having the three-phase bridge circuit mounted thereon.

6. An electric power tool, comprising:

a housing body part capable of housing a brushless DC motor as a driving source;

a grip part formed to protrude from a lateral part of the housing body part;

a switch part provided in such a position that allows a user to engage a finger of the user with the switch part while the user holds the grip part;

a battery capable of supplying a power to the blushless DC motor;

a three-phase bridge circuit configured to control the blushless DC motor and including switching devices; and

a capacitor connected in parallel with the three-phase bridge circuit;

wherein the three-phase bridge circuit is disposed proximal to the brushless DC motor within the housing body part, and the capacitor is disposed at a position closer to the three-phase bridge circuit than the switch part.

7. The electric power tool according to claim 6, further comprising electric conductors electrically connect between the capacitor and the three-phase bridge circuit and are configured to connect the capacitor and the three-phase bridge circuit at the shortest distance.

8. The electric power tool according to claim 6, wherein the electric power tool is a rotary impact driver.

9. An electric power tool, comprising:

a DC motor;

a control circuit capable of controlling the DC motor;

a capacitor electrically connected to the control circuit;

a switch electrically connected to the control circuit, so that the DC motor is driven under the control of the control circuit when the switch is operated;

wherein the capacitor is positioned closer to the control circuit than the switch.

10. An electric power tool, comprising:

a brushless DC motor as a driving source;

a control circuit for controlling the brushless DC motor; and

a capacitor connected in parallel with the control circuit;

wherein the control circuit is positioned proximate to the brushless DC motor, and the capacitor is disposed at a position proximal to the control circuit.

11. The electric power tool according to claim 10, wherein the control circuit includes a three-phase bridge circuit.

12. The electric power tool according to claim 10, further comprising:

a housing body part capable of housing the brushless DC motor;

a grip part formed to protrude from a lateral part of the housing body part; and

a switch part provided in the grip part;

wherein the capacitor is mounted on an electrical circuit board of the switch part.

13. The electric power tool according to claim 10, further comprising:

a housing body part capable of housing the brushless DC motor; and

a grip part formed to protrude from a lateral part of the housing body part;

wherein the capacitor is positioned at a boundary region between the housing part and the grip part.

14. The electric power tool according to claim 10, wherein the capacitor is mounted on an electrical circuit board having the three-phase bridge circuit mounted thereon.