Power tool

Patent metadata

Field	Value
Publication number	US-2017129092-A1
Application number	US-201615350408-A
Country	US
Kind code	A1
Filing date	Nov 14, 2016
Priority date	Nov 11, 2015
Publication date	May 11, 2017
Grant date	—

Abstract

It is an object of the invention to provide a technique for rationally transmitting rotation of a motor to a tool accessory. According to the invention, a representative screwdriver 100 having a motor 110 and a driving mechanism 120 is provided. The driving mechanism 120 has a driving gear 125 , a transmitting element 140 and a retainer 130 . The transmitting element 140 consists of three or more rollers 140 a . A tool bit 119 is held by a spindle 160 which is movable in a longitudinal direction. When the spindle 160 is located in a second position, the rollers 140 a are held between the driving gear 125 and a spring receiver 150 so that the spindle 160 is rotationally driven.

First claim

1 . A power tool, which performs a prescribed operation by rotationally driving a tool accessory detachably held in a front end region of a tool body, comprising:
a motor, a tool accessory holding part that is configured to be rotatable and to hold the tool accessory, and a rotary drive mechanism that transmits rotation of the motor to the tool accessory holding part, wherein: the tool accessory holding part is configured to be switched by a user between a first position close to the front end region and a second position apart from the front end region in a rotation axis direction of the tool accessory holding part, the rotary drive mechanism includes: a driving member that is rotationally driven by the motor, a driven member that is arranged coaxially with the driving member and connected to the tool accessory holding part, a transmitting element that is disposed between the driving member and the driven member and can be moved between a holding position to be held between the driving member and the driven member and a holding disabled position not to be held between the driving member and the driven member around a rotation axis of the driving member, and a transmitting member retaining element for retaining the transmitting element, the transmitting element includes a plurality of transmitting members that define at least a first transmitting member, a second transmitting member and a third transmitting member, the transmitting member retaining element includes a plurality of transmitting member retaining parts that define at least a first transmitting member retaining part for retaining the first transmitting member, a second transmitting member retaining part for retaining the second transmitting member and a third transmitting member retaining part for retaining the third transmitting member, the transmitting member retaining element is disposed on a prescribed circumference around the rotation axis of the driving member, a transmitting member non-retaining part is formed at a position point-symmetric to the first transmitting member retaining part on the circumference, the circumference defines one semi-circle and the other semi-circle by a diameter passing through the first transmitting member retaining part, and the second transmitting member retaining part is arranged on the one semi-circle and the third transmitting member retaining part is arranged on the other semi-circle, when the tool accessory holding part is located in the first position, the transmitting members are placed in the holding disabled position, so that transmission of rotation of the driving member to the driven member is interrupted, and when the tool accessory holding part is switched to the second position by user's operation, the transmitting members are placed in the holding position, so that rotation of the driving member is transmitted to the driven member.

2 . The power tool as defined in claim 1 , wherein the transmitting member retaining parts are arranged at equal intervals on the circumference.

3 . The power tool as defined in claim 1 , wherein the transmitting element includes totally nine transmitting members including the first, second and third transmitting members.

4 . The power tool as defined in claim 1 , wherein:
the rotary drive mechanism has a retainer that is arranged coaxially with the driving member and connected to the tool accessory holding part, the retainer has a cylindrical shape and has the transmitting member retaining element and a first engagement part extending inward of the transmitting member retaining element, the driven member has a second engagement part that can engage with a region of the first engagement part located inward of the transmitting member retaining element, when the tool accessory holding part is located in the first position, the first engagement part and the second engagement part are disengaged from each other and the transmitting members are placed in the holding disabled position, and when the tool accessory holding part is located in the second position, the first engagement part and the second engagement part are engaged with each other and thereby the transmitting members are placed in the holding position.

5 . The power tool as defined in claim 4 , further comprising:
a rotation preventing part that prevents rotation of the tool accessory holding part by engaging with the tool accessory holding part when the tool accessory holding part is located in the first position, wherein: the tool accessory holding part is configured to be switched to an intermediate position between the first position and the second position in the rotation axis direction of the tool accessory holding part, when the tool accessory holding part is located in the first position, the tool accessory holding part and the rotation preventing part are engaged with each other, the driving member and the retainer are separated from each other, and the first engagement part and the second engagement part are disengaged from each other, when the tool accessory holding part is located in the intermediate position, the tool accessory holding part and the rotation preventing part are disengaged from each other, the driving member and the retainer come in contact with each other so that the tool accessory holding part is rotationally driven, and the first engagement part and the second engagement part are disengaged from each other, and when the tool accessory holding part is located in the second position, the tool accessory holding part and the rotation preventing part are disengaged from each other, the driving member and the retainer come in contact with each other, and the first engagement part and the second engagement part are engaged with each other, so that the transmitting members are placed in the holding position and rotation of the driving member is transmitted to the driven member.

6 . The power tool as defined in claim 5 , wherein the rotation preventing part and the tool accessory holding part are engaged in surface contact with each other.

7 . The power tool as defined in claim 1 , wherein:
the driving member has a bottom wall, a side wall and a housing space surrounded by the bottom wall and the side wall, the bottom wall has an opening through which the tool accessory holding part is inserted, the housing space houses at least part of the rotary drive mechanism, and the side wall has a spiral groove for holding grease which is supplied to the rotary drive mechanism.

8 . The power tool as defined in claim 1 , wherein:
when the tool accessory holding part is switched to the second position by user's operation, the first, second and third transmitting members are placed in the holding position.

9 . The power tool as defined in claim 1 , wherein:
the transmitting element includes three or more odd number of transmitting members including the first, second and third transmitting members.

10 . The power tool as defined in claim 1 , wherein:
regions located in point symmetry to the transmitting members with respect to the rotation axis of the driving member define a transmitting member non-arrangement region.

Assignees

• Makita Corp

Inventors

• Kimura Kazuya

Classifications

• 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

• B25F5/001 Primary

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

• B25B23/14

  Arrangement of torque limiters or torque indicators in wrenches or screwdrivers (couplings for transmitting rotation or clutches F16D; devices for measuring torque per se G01L) · CPC title