Electric power tool

• US 20090255361A1
• Filed: 03/24/2009
• Published: 10/15/2009
• Est. Priority Date: 04/10/2008
• Status: Active Grant

• Current Assignee: Panasonic Electric Works Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Electric Works Company Limited (Panasonic Holdings Corporation)
• Inventors: Inagaki, Kenichiro, Sekino, Fumiaki, Yamada, Yutaka
• Granted Patent: US 8,083,007 B2
• Time in Patent Office: Days
• US Class Current: 74/473.230
• CPC Class Codes: B25F 5/001 Gearings, speed selectors, clutches or the like specially adapted for rotary tools
• CPC Class Codes: Y10T 74/20098 Separate actuator to disengage restrictor

Abstract

An electric power tool includes a motor, a speed reducer unit arranged to deliver the rotational power of the motor and provided with gears, a housing arranged to accommodate the motor and the speed reducer unit, and a speed changing unit for changing a gear reduction ratio of the speed reducer unit. The speed changing unit is arranged in such a position as to be operable outside the housing. The speed changing unit includes an operation lever slidingly operable in a speed changing direction when pushed, an operation detector unit for detecting the operation lever to control electric power supplied to the motor, a shift unit for changing the gear reduction ratio of the speed reducer unit in response to sliding movement of the operation lever, and a slide restraint unit for restraining the sliding operation of the operation lever until the operation detector unit detects the operation lever.

Claims

1. An electric power tool comprising:

a motor as a driving power source for generating rotational power;

a speed reducer unit arranged to deliver the rotational power of the motor and provided with two or more gears;

a driving unit arranged to deliver the rotational power from the speed reducer unit to a tip end tool;

a housing arranged to accommodate the motor, the speed reducer unit and the driving unit therein and provided with a handle portion; and

a speed changing unit for changing a gear reduction ratio of the speed reducer unit, the speed changing unit arranged in such a position as to be operable outside the housing,

wherein the speed changing unit comprises an operation lever slidingly operable in a speed changing direction when pushed, an operation detector unit for detecting the operation lever to control electric power supplied to the motor, a shift unit for changing the gear reduction ratio of the speed reducer unit in response to sliding movement of the operation lever, and a slide restraint unit for restraining the sliding operation of the operation lever until the operation detector unit detects the operation lever.

2. The electric power tool of claim 1, wherein the slide restraint unit includes a projection portion provided in one of mutually facing surfaces of the operation lever and the housing and a guide portion provided in the other surface, the projection portion and the guide portion being configured in such a manner as to restrain sliding movement of the operation lever in the speed changing direction when the push lever is in a non-pushed position but permit the sliding movement of the operation lever in the speed changing direction when the push lever is in a pushed position.

3. The electric power tool of claim 2, wherein the guide portion includes a slide operation groove extending in the speed changing direction and a pair of push operation grooves extending in a pushing direction of the operation lever from the opposite ends of the slide operation groove, the slide operation groove and the push operation grooves being continuously formed to have a generally square bracket shape.

4. The electric power tool of claim 3, wherein the push operation grooves are inclined at an obtuse angle with respect to the slide operation groove.

5. The electric power tool of claim 2, wherein the speed changing unit further comprises a resilient member for biasing the projection portion against the guide portion in a direction to restrain the movement of the operation lever and a restraint releasing unit for moving the projection portion to permit the movement of the operation lever when the operation lever is pushed.

6. The electric power tool of claim 2, wherein the projection portion is provided to the operation lever and the guide portion is provided to the housing.

7. The electric power tool of claim 1, wherein the operation detector unit is designed to detect the operation lever when the operation lever is in a generally middle position between a non-pushed position and a pushed position.

8. The electric power tool of claim 1, wherein the operation lever includes an interrupter plate having a predetermined length in the speed changing direction, the operation detector unit including a sensor for optically detecting the interrupter plate when the operation lever is pushed.

9. The electric power tool of claim 1, wherein the operation lever has an operation surface depressed inwards from an outer surface of the housing.