Power tool

Patent metadata

Field	Value
Publication number	US-9505097-B2
Application number	US-201313898014-A
Country	US
Kind code	B2
Filing date	May 20, 2013
Priority date	May 29, 2012
Publication date	Nov 29, 2016
Grant date	Nov 29, 2016

Abstract

A power tool enabled to detect an inadvertent rotation at higher accuracy includes a first sensor that detects a first driving information corresponding to a kinetic movement state of the tool body when the tool body is rotated around a longitudinal axis of the tool bit in the event of a working operation of the power tool, a second sensor that detects a second driving information corresponding to an output torque of the tool bit driven by the motor, and a controller connected to the first sensor and the second sensor for controlling the power tool. The controller is configured to calculate holding information corresponding to a holding force of a user to hold the tool body based on the first driving information and the second driving information and control the driving of the power tool based on the holding information.

First claim

What we claim is:

1. A hand-held power tool configured to drive a removable tool bit about a longitudinal axis, the power tool comprising:
a tool body;
a tool holder configured to removably hold the tool bit;
a motor that is housed in the tool body, the motor configured to rotatably drive the tool bit;
a torque transmission path connecting the motor to the tool holder;
a first sensor that detects a first driving information corresponding to a kinetic movement state of the tool body when the tool body is rotated around the longitudinal axis in the event of a working operation of the power tool;
a second sensor that detects a second driving information corresponding to an output torque of the tool bit driven by the motor; and,
a controller that controls the power tool, wherein the controller is connected to the first sensor and the second sensor, wherein the controller calculates a holding information corresponding to holding force of the user to hold the tool body based on the first driving information and the second driving information, and controls the driving of the power tool based on the holding information.

2. The power tool according to claim 1 , wherein the first driving information is information selected from the group consisting of an acceleration, a velocity and a displacement of the tool body.

3. The power tool according to claim 1 , wherein the second sensor is defined by a load-cell provided on the torque transmission path from the motor to the tool bit.

4. The power tool according to claim 1 , wherein the first driving information is defined by an angular acceleration of the tool body around the longitudinal axis and the second driving information is defined by an output torque of the tool bit and wherein the controller integrates the angular acceleration and the output torque in each predetermined time period and calculates the holding information based on the respective integrated values of the angular acceleration and the output torque.

5. The power tool according to claim 1 , wherein the controller controls torque transmission on the torque transmitting path from the motor to the tool bit based on the holding information.

6. The power tool according to claim 5 further comprising an electromagnetic clutch provided on the torque transmission path, wherein the controller controls the electromagnetic clutch.

7. The power tool according to claim 4 , wherein the holding information corresponds to a user's ability to disrupt unintended motion of the power tool body such that a low holding force corresponds to a low ability of a user to disrupt unintended motion of the tool body, and a high holding force corresponds to a high ability of a user to disrupt unintended motion of the tool body.

8. The power tool according to claim 1 , further comprising an electromagnetic clutch provided on the torque transmission path, wherein the controller controls the electromagnetic clutch so as to disrupt the torque transmission path based on the holding information in order to prevent inadvertent swinging of the power tool, and wherein the holding information corresponds to a user's ability to disrupt unintended motion of the power tool body such that a low holding force corresponds to a low ability of a user to disrupt unintended motion tool body, and a high holding force corresponds to a high ability of a user to disrupt unintended motion of the tool body.

9. The power tool according to claim 8 , wherein the controller controls the electromagnetic clutch to disrupt the torque transmission path sooner for a low calculated holding force than for a high calculated holding force.

10. The power tool according to claim 1 , wherein the controller controls the power tool to disrupt the torque transmission path sooner for a low calculated holding force than for a high calculated holding force.

11. The power tool according to claim 1 , wherein the torque transmission path includes:
an output shaft configured to be rotated by the motor;
a first intermediate shaft configured with a clutch, the clutch configured to disrupt the torque transmission path based on the holding information, the first intermediate shaft configured to be driven by the output shaft; and
a second intermediate shaft driven by the first intermediate shaft and configured to drive the removable tool bit about the longitudinal axis,
wherein the output shaft, the first intermediate shaft, and the second intermediate shaft are parallel to each other but not coaxially aligned with each other.

12. The power tool according to claim 11 , wherein a first torque generated about the output shaft is lower than a second torque generated about the first intermediate shaft, which is lower than a third torque generated about the second intermediate shaft.

13. The power tool according to claim 12 , wherein the second sensor is configured to detect driving information corresponding to the third torque generated about the second intermediate shaft.

14. The power tool according to claim 1 , wherein the controlling of the power tool based on the holding information consists of disrupting the torque transmission path in order to prevent an uncontrollable state in which the user is unable to prevent an inadvertent swinging motion of the power tool.

15. A hand-held power tool configured to drive a removable tool bit about a longitudinal axis, the power tool comprising:
a tool body;
a tool holder configured to removably hold the tool bit;
a motor that is housed in the tool body, the motor configured to rotatably drive the tool bit;
a torque transmission path connecting the motor to the tool holder;
a first sensor that detects a first driving information corresponding to a kinetic movement state of the tool body when the tool body is rotated around the longitudinal axis in the event of a working operation of the power tool;
a second sensor that detects a second driving information corresponding to an output torque of the tool bit driven by the motor; and
a controller that controls the power tool, wherein the controller is connected to the first sensor and the second sensor, wherein the controller calculates a holding information corresponding to holding force of the user to hold the tool body and controls the driving of the power tool based on the holding information, wherein the first driving information is defined by an angular acceleration of the tool body around the longitudinal axis and the second driving information is defined by an output torque of the tool bit, and wherein the controller integrates the angular acceleration and the output torque in each predetermined time period and calculates the holding information based on the respective integrated values of the angular acceleration and the output torque.

Assignees

• Makita Corp

Inventors

• Aoki Yonosuke
• Fujinami Katsuhito

Classifications

• B25D16/003 Primary

  Clutches specially adapted therefor · CPC title

• B25F5/001

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

• B23Q15/08 Primary

  Control or regulation of cutting velocity (B23Q15/12 takes precedence) · CPC title

• B25F5/00

  Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for · CPC title

• B25D2250/165

  Overload clutches, torque limiters · CPC title