Power tool

Abstract

It is an object of the present invention to provide an effective technique for reducing the size of a mode switching device of a power tool. A representative power tool comprising a mode switching device that includes a mode switching member turned by manual operation, a linearly moving driven-side member and a mode switching mechanism actuated by linear motion of the driven-side member. The actuating member is disposed on the mode switching member such that the initial position of the actuating member is located in a position displaced in a radial direction from the rotation axis of the mode switching member. When the mode switching member is turned, the actuating member revolves in a circular arc movement in contact with the driven-side member to linearly move the driven-side member. The actuating member can move radially inward of the mode switching member from the initial position toward the rotation axis of the mode switching member with respect to the mode switching member. The power tool further includes an elastic element elastically deformed by the actuating member when the actuating member moves radially inward from the initial position. When the driven-side member is prevented firm moving linearly by interruption of the movement of the mode switching mechanism during turning operation of the mode switching member, the elastic element is deformed to allow the mode switching member to be turned. When the interruption of the movement of the mode switching mechanism is resolved, the actuating member moves back to the initial position by the accumulated spring force of the elastic element, which causes the driven-side member to linearly move.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional side view schematically showing an entire hammer drill according to an embodiment of the invention.

FIG. 2 is a sectional view of an essential part of the hammer drill in the state in which a power transmitting mechanism is in a power transmission state.

FIG. 3 is a sectional view of the essential part of the hammer drill in the state in which the power transmitting mechanism is in a power transmission interrupted state.

FIG. 4 is an enlarged sectional view showing a mode switching mechanism.

FIG. 5 is a view showing only the mode switching mechanism.

FIG. 6 is a view showing the state in which a cylindrical part of an operating member of the mode switching mechanism is mounted to a crank housing.

FIG. 7 is a perspective view showing the structure for assembling an eccentric pin and a torsion spring to the cylindrical part of the operating member, in which FIG. 7(A) shows the state before assembling, FIG. 7(B) shows the state during assembling, and FIG. 7(C) shows the state after assembling.

FIG. 8 is a plan view showing the mode switching mechanism in the state in which the operating member is turned to a hammer drill mode position and the clutch mechanism is engaged.

FIG. 9 is a plan view showing the mode switching mechanism in the state in which the operating member is turned to a hammer drill mode position and the switching movement of the clutch mechanism is interrupted.

FIG. 10 is a plan view showing the state in which the operating member is further turned from the state shown in FIG. 9.

FIG. 11 is a plan view showing the mode switching mechanism in the state in which the operating member is turned to one hammer mode position and the clutch mechanism is engaged.

FIG. 12 is a plan view showing the mode switching mechanism in the state in which the operating member is turned to one hammer mode position and the switching movement of the clutch mechanism is interrupted.

FIG. 13 is a plan view showing the state in which the operating member is further turned from the state shown in FIG. 12.

FIG. 14 is a plan view showing the mode switching mechanism in the state in which the operating member is turned to the other hammer mode position and the clutch mechanism is engaged.

Claims

1. A power tool comprising a mode switching device that switches a driving mode of a tool bit among a plurality of different driving mode wherein the mode switching device includes: a mode switching member that can be turned by manual operation,a driven-side member that can linearly move in a direction crossing a rotation axis of the mode switching member,a mode switching mechanism that is actuated by linear motion of the driven-side member,an actuating member that is disposed on the mode switching member such that the initial position of the actuating member is located in a position displaced in a radial direction from the rotation axis of the mode switching member, wherein, when the mode switching member is turned, the actuating member is caused to revolve in a circular arc movement in contact with the driven-side member, thereby causing the driven-side member to linearly move via components of the circular arc movement in the direction of the linear movement of the driven-side member, wherein the actuating member can move radially inward of the mode switching member from the initial position toward the rotation axis of the mode switching member with respect to the mode switching member andan elastic element that is drastically deformed by the actuating member when the actuating member moves radially inward from the initial position, whereby the elastic element builds up a spring force to return the actuating member to the initial position,wherein, when the driven-side member is prevented from moving linearly by interruption of the movement of the mode switching mechanism during turning operation of the mode switching member for mode change, the actuating member moves radially inward of the mode switching member while elastically deforming the elastic element, thereby allowing the mode switching member to be turned, and when the interruption of the movement of the mode switching mechanism is resolved and the linear movement of the driven-side member is allowed in the state in which the mode switching member is turned, the actuating member moves back to the initial position by the accumulated spring force of the elastic element, which causes the driven-side member to linearly move.

2. The power tool as defined in claim 1, wherein the radially inward movement of the actuating member with respect to the mode switching member is a swinging movement on a fixed point other than the rotation axis of the mode switching member.

3. The power tool as defined in claim 1, wherein the radially inward movement of the actuating member with respect to the mode switching member is a swinging movement on a fixed point other than the rotation axis of the mode switching member and wherein the actuating member can swing on either of two points which are substantially symmetrically positioned with respect to a line connecting the rotation axis of the mode switching member and the center of the actuating member placed in the initial position.

4. The power tool as defined in claim 1 further comprising a tool body having a mounting hole in which the mode switching member is mounted, wherein the mode switching member includes a circular portion which is rotatably fitted in the mounting hole, the circular portion having a recess formed along the direction of the rotation axis, the elastic element and the entire actuating member except for a portion which contacts the driven-side member being disposed within the recess.

5. The power tool as defined in claim 1, wherein the radially inward movement of the actuating member with respect to the mode switching member is a swinging movement on a fixed point other than the rotation axis of the mode switching member and wherein the actuating member can swing on either of two points which at substantially symmetrically positioned with respect to a line connecting the rotation axis of the mode switching member and the center of the actuating member placed in the initial position, wherein the mode switching member has two engagement recesses that are substantially symmetrically positioned with respect to a line connecting the rotation axis of the mode switching member and the center of the actuating member placed in the initial position,the actuating member has two engagement portions which can disengageably and rotatably engage with the associated engagement recesses andthe elastic element comprises a torsion spring and includes two arms extending radially outward, and one of the arms of the torsion spring is held in contact with one of the engagement portions such that the one engagement portion engages with one of the engagement recesses, while the other arm of the torsion spring is held in contact with the other engagement portion such that the other engagement portion engages with the other engagement recess.

6. The power tool as defined in claim 1, wherein the tool bit of the power tool is driven at least in any two of a hammer mode, drill mode and hammer drill mode.