Electric power tool

• US 20100283332A1
• Filed: 05/11/2010
• Published: 11/11/2010
• Est. Priority Date: 05/11/2009
• Status: Active Grant

• Current Assignee: Koki Holdings Co., Ltd.
• Original Assignee: Hitachi KOKI Company Limited (Koki Holdings Co., Ltd.)
• Inventors: Takeda, Takashi, Komuro, Yoshihiro, TOUKAIRIN, Junichi, Kawahata, Yasuoki, Kishima, Yuji
• Granted Patent: US 8,513,838 B2
• Time in Patent Office: Days
• US Class Current: 310/50
• CPC Class Codes: B25F 5/008 Cooling means
• CPC Class Codes: H02K 11/33 Drive circuits, e.g. power electronics H02K11/38 takes precedence
• CPC Class Codes: H02K 2211/03 Machines characterised by circuit boards, e.g. pcb
• CPC Class Codes: H02K 7/145 Hand-held machine tool

Abstract

An electric power tool includes: a motor including a motor shaft; a tip tool driven by the motor; a housing that houses the motor; a switching element for driving the motor; and a bearing that can retain the motor shaft. The switching element is provided so as to overlap with the bearing in a direction of the motor shaft inside the housing.

Claims

1. An electric power tool including:

a motor including a motor shaft;

a tip tool driven by the motor;

a housing that houses the motor;

a switching element for driving the motor; and

a bearing that is capable of retaining the motor shaft, wherein

the switching element is provided so as to overlap with the bearing in a direction of the motor shaft inside the housing.

2. The electric power tool according to claim 1, wherein:

the housing includes a motor housing portion that houses the motor, and a grip housing portion that extends downward from the motor housing portion; and

the bearing and the switching element are provided in the motor housing portion.

3. The electric power tool according to claim 2, wherein:

the housing is a left and right dividable housing; and

the bearing is retained by a rib that is provided in the motor housing portion, and extends in a horizontal direction.

4. The electric power tool according to claim 3, wherein

the motor shaft is provided so as to be substantially orthogonal to a circuit board mounted with the switching element.

5. The electric power tool according to claim 4, wherein:

a plurality of the switching elements are provided; and

a portion of the switching elements is provided in a prone state on the circuit board, whereas another portion of the switching elements is provided in an upright state on the circuit board, and overlaps with the bearing.

6. The electric power tool according to claim 5, wherein

the rib is provided behind in the motor shaft direction with respect to the portion of the switching elements.

7. The electric power tool according to claim 5, wherein:

the left and right dividable housing is fixable by a screw extending in the horizontal direction;

a screw boss for fixing the screw is provided in the motor housing; and

the another portion of the switching elements is disposed between the screw boss and the bearing.

8. An electric power tool comprising:

a housing including a body housing portion extending from one end to the other end;

a brushless motor portion that extends in a direction from the one end toward the other end in the body housing portion, and has a motor rotation shaft supported by first and second shaft bearing portions respectively provided on the one end side and the other end side in the body housing portion, and a stator coil provided on an outer periphery of an intermediate portion of the motor rotation shaft;

an inverter circuit board that is mounted with a plurality of semiconductor switching elements in order to supply a power source to the stator coil and housed on the one end side in the body housing portion;

a tip tool mounting portion that is driven on a basis of a rotational output of the motor rotation shaft, and provided on the other end side of the body housing portion; and

a drive power transmission portion that is provided on the other end side of the body housing portion to transmit the rotational output of the motor rotation shaft to the tip tool mounting portion, wherein;

the inverter circuit board is disposed to extend in a direction that crosses a shaft direction of the motor rotation shaft in a space in the body housing portion between the first shaft bearing portion and the stator coil provided on the one end side of the body housing portion;

a mounting surface for the semiconductor switching elements of the inverter circuit board is disposed so as to face the first shaft bearing portion; and

a first group element in the plurality of semiconductor switching elements mounted on the mounting surface of the inverter circuit board is mounted adjacently to the first shaft bearing portion in a space in the body housing portion between the mounting surface and the one end so as to have a height that exceeds a separation distance from the mounting surface to the first shaft bearing portion.

9. The electric power tool according to claim 8, wherein

second group element in the plurality of semiconductor switching elements mounted on the mounting surface of the inverter circuit board is fitted in a space in the body housing portion between the mounting surface and the first shaft bearing portion so as to have a height that is lower than the separation distance from the mounting surface to the first shaft bearing portion.

10. The electric power tool according to claim 8, wherein:

the first and second group semiconductor switching elements are semiconductor power transistors respectively including insertable lead lines;

the insertable lead line of the first group element is fitted in a state vertical to the mounting surface of the inverter circuit board; and

the insertable lead line of the second group element is bent with respect to the mounting surface of the inverter circuit board, and fitted such that package surface of the semiconductor power transistor are brought into a state parallel to the mounting surface.

11. The electric power tool according to claim 8, wherein

the motor rotation shaft is orthogonal to the inverter circuit board via a through hole provided in the inverter circuit board.

12. The electric power tool according to claim 8, wherein

the housing has a handle housing portion that branches and extends from the direction of the extension of the body housing portion.

13. The electric power tool according to claim 8, wherein:

the housing is formed by tightening halved housing members with a screw extending in a horizontal direction, the halved housing members being formed by dividing the housing into two in the horizontal direction at a vertical surface crossing a central axis of the motor rotation shaft;

and the first shaft bearing portion is retained by a hole formed in a central portion of a rib that is formed on the one end of the body housing portion and extends in the horizontal direction.

14. The electric power tool according to claim 13, wherein

the second group semiconductor switching element mounted on the inverter circuit board is mounted in a space in the body housing portion between the rib formed on the one end and the mounting surface.

15. The electric power tool according to claim 14, wherein:

the halved housing member has a screw boss threadably engaging with the screw for tightening the halved housing members at the one end of the body housing portion; and

the first group semiconductor switching element is fitted adjacently to the first shaft bearing portion in a space in the body housing portion between the screw boss and the first shaft bearing portion.

16. The electric power tool according to claim 9, wherein:

the inverter circuit board has the mounting surface of a circular shape, and a through hole through which the motor rotation shaft crosses, in a central portion of the circular-shaped mounting surface;

the first group semiconductor switching element comprises a plurality of first group semiconductor switching elements;

the second group semiconductor switching element comprises a plurality of second group semiconductor switching elements;

the first group semiconductor switching elements include two pairs of semiconductor power transistors respectively mounted in two pairs of first regions facing each other and sandwiching the through hole in a peripheral portion of the through hole in the mounting surface; and

the second group semiconductor switching elements include one pair of semiconductor power transistors respectively mounted in one pair of second regions facing each other and sandwiching the through hole in the peripheral portion of the through hole in the mounting surface.

17. The electric power tool according to claim 16, wherein

a mounting height of the second group semiconductor power transistors mounted in the second region of the mounting surface is lower than a height of the first group semiconductor power transistors mounted in the first region of the mounting surface.

18. The electric power tool according to claim 8, wherein:

a cooling fan using the motor rotational shaft as a rotation shaft is provided in a space in the body housing portion between the second shaft bearing portion provided on the other end side of the body housing portion and the stator coil; and

a ventilation port is provided on the one end side of the body housing portion.

19. An electric power tool comprising:

a brushless motor including a stator coil;

a housing that houses the brushless motor;

a circuit board housed in the housing;

a plurality of switching elements that comprises a first switching element and a second switching element and that are provided on the circuit board and that allows electric current to pass through the stator coil;

wherein

the first switching element is implemented on the circuit board vertically with respect to the circuit board, and the second switching element is implemented on the circuit board in parallel with the circuit board.