Power tool

Patent metadata

Field	Value
Publication number	US-9815182-B2
Application number	US-201414491542-A
Country	US
Kind code	B2
Filing date	Sep 19, 2014
Priority date	Sep 19, 2013
Publication date	Nov 14, 2017
Grant date	Nov 14, 2017

Abstract

A screw driver ( 100 ) which comprises a motor ( 110 ) and a rotation transmission mechanism ( 120 ) is provided. The rotation transmission mechanism ( 120 ) comprises a driving gear ( 125 ), a spindle ( 150 ), a roller ( 141 ) and a retainer ( 130 ). The retainer ( 130 ) moves the roller ( 140 ) in a circumference direction of the spindle ( 150 ) and thereby a position of the roller ( 140 ) between a transmittable position and a non-transmittable position is switched.

First claim

What is claimed is:

1. A power tool which rotationally drives a tool bit, comprising:
a motor which includes an output shaft, and
a rotation transmission mechanism which transmits rotation of the output shaft to the tool bit and thereby rotationally drives the tool bit,
wherein the rotation transmission mechanism comprises:
a driving member which includes a rotation shaft, the driving member being rotationally driven by the motor,
a driven member to which the tool bit is attached, the driven member being disposed coaxially with the rotation shaft,
a transmitting member which is disposed between the driving member and the driven member and is movable in a circumference direction of the rotation shaft between a transmittable position in which rotation of the output shaft is transmitted to the driven member via the transmitting member and a non-transmittable position which is different position from the transmittable position in which the transmission of rotation is interrupted, and
a switching member which is configured to switch a position of the transmitting member between the transmittable position and the non-transmittable position by moving in the circumference direction of the rotation shaft with respect to the driven member,
and wherein the driven member is configured to move between a first position and a second position in an axial direction of the rotation shaft,
and wherein the switching member is allowed to move in the circumference direction of the rotation shaft with respect to the driven member based on the position of the driven member in the axial direction of the rotation shaft, and the transmitting member is switched between the transmittable position and the non-transmittable position by the movement of the switching member.

2. The power tool according to claim 1 , wherein the driven member is moved to the second position from the first position by pushing against a workpiece via the tool bit,
when the output shaft is rotated in a predetermined first direction and the driven member is positioned in the first position, the switching member is prevented from moving in the circumference direction of the rotation shaft and thereby the switching member holds the transmitting member in the non-transmittable member,
and when the output shaft is rotated in the first direction and the driven member is moved to the second position from the first position, the switching member is allowed to move in the circumference direction of the rotation shaft and thereby the switching member switches the position of the transmitting member to the transmittable position and the transmitting member transmits rotation of the output shaft in the first direction to the driven member.

3. The power tool according to claim 2 , when the output shaft is rotated in a second direction opposed to the first direction and the driven member is positioned in the first position, the switching member is allowed to move in the circumference direction of the rotation shaft and thereby the switching member switches the position of the transmitting member to the transmittable position and the transmitting member transmits rotation of the output shaft in the second direction to the driven member.

4. The power tool according to claim 1 , wherein the rotation transmission mechanism includes an axially movable element which is configured to move in the axial direction of the rotation shaft in accordance with movement of the driven member in the axial direction of the rotation shaft,
and wherein the axially movable element moves the switching member in the circumference direction of the rotation shaft by moving in the axial direction of the rotation shaft.

5. The power tool according to claim 4 , wherein the axially movable element is formed integrally with the driven member.

6. The power tool according to claim 4 , wherein the axially movable element is formed as a spherical member which is separated from the driven member.

7. The power tool according to claim 4 , wherein the axially movable element is configured to normally prevent a relative movement of the switching member with respect to the driven member in the circumference direction,
and wherein the axially movable element is moved in the axial direction of the rotation shaft by movement of the driven member to the second position from the first position and thereby the relative movement of the switching member is allowed,
in a state that the relative movement of the switching member is allowed, when the driving member is rotated, the switching member switches the position of the transmitting member to the transmittable position from the non-transmittable position by rotation of the driving member.

8. The power tool according to claim 4 , wherein the power tool is constructed as a screw fastening tool which performs a screw operation in which the tool bit fastens a screw into a workpiece, further comprising:
a workpiece contact portion which is contactable with a workpiece during the screw operation,
wherein in a state that the workpiece contact portion contacts with a workpiece, the driven member moves to be close to a workpiece in the axial direction of the tool bit by fastening a screw by the tool bit,
and wherein the axially movable element moves in the axial direction in accordance with the axial movement of the driven member during the screw operation and thereby the axially movable element moves the switching member in the circumference direction and the switching member switches the position of the transmitting member to the non-transmittable position from the transmittable position.

9. The power tool according to claim 8 , wherein one component of the axially movable element and the switching member has a guide portion which extends in the circumference direction of the rotation shaft, and the other component has a contact portion which is contactable with the guide portion,
in a state that the guide portion and the contact portion are contacted with each other during the screw operation, the axially movable element moves to be close to the tool bit in the axial direction and thereby the switching member is moved in the circumference direction of the rotation shaft by the axially movable element, and the switching member switches the position of the transmitting member to the transmittable position from the non-transmittable position by movement of switching member in the circumference direction.

10. The power tool according to claim 1 , wherein one component of the driving member and the driven member is formed as a cylinder and the other component is formed as a polygonal column arranged coaxially with the cylinder of said one component,
and wherein the transmitting member comprises a plurality of transmitting elements each of which is disposed to correspond to each side surface of the polygonal column.

11. The power tool according to claim 10 , wherein the driven member is disposed inside the driving member, the inside of the driving member being formed as a cylinder, the outside of the driven member being formed as a polygonal column,
and wherein the transmitting element is formed as a roller and each transmitting element is disposed to correspond to each side surface of the polygonal column of the driven member.

12. The power tool according to claim 10 , when the output shaft is rotated in the first direction, the transmitting element belonging to a first group is switched to the transmittable position from the non-transmittable position by pushing the driven member against a workpiece via the tool bit,
and when the output shaft is rotated in the second direction, in a state that the transmitting element of the first gro

Assignees

• Makita Corp

Inventors

• Ikuta Hiroki

Classifications

• B25F5/001 Primary

  Gearings, speed selectors, clutches or the like specially adapted for rotary tools · CPC title

• B25B21/00 Primary

  Portable power-driven screw or nut setting or loosening tools; (details or components, e.g. casings, bodies, of portable power-driven tools not particularly related to the operation performed B25F5/00; {for mounting or dismounting wheels B60B29/006}); Attachments for drilling apparatus serving the same purpose (machines B23P19/06) · CPC title

• B25B15/06

  operated by axial movement of the handle · CPC title