Power tool and kickback detection method therefor

Patent metadata

Field	Value
Publication number	US-11015759-B2
Application number	US-201816176310-A
Country	US
Kind code	B2
Filing date	Oct 31, 2018
Priority date	Nov 2, 2017
Publication date	May 25, 2021
Grant date	May 25, 2021

Abstract

A power tool and a detection method for the power tool. The detection method includes collecting acceleration data, via use of an acceleration sensor of the power tool, along a tangential direction of a rotation axis of a working portion of the power tool, determining whether a proportion of the collected acceleration data that exceeds a first acceleration threshold in a preset time window exceeds a preset value, and determining that a kickback occurs in the power tool when the proportion exceeds the preset value.

First claim

What is claimed is:

1. A detection method for a power tool, comprising:
collecting a plurality of acceleration data points within a preset time window, via use of an acceleration sensor of the power tool, along a tangential direction of a rotation axis of a working portion of the power tool, wherein each of the plurality of acceleration data points is a digital signal;
calculating a proportion representative of the number of collected acceleration data points whose acceleration value exceeds a first acceleration threshold to the total number of collected acceleration data points within the preset time window, wherein the acceleration data points whose acceleration exceeds a first acceleration threshold may be non-adjacent acceleration data points;
determining whether the calculated proportion exceeds a preset proportion value; and
determining that a kickback occurs in the power tool when the calculated proportion exceeds the preset proportion value.

2. The method according to claim 1 , wherein the digital signal is representative of a numeric value.

3. The method according to claim 1 , wherein determining whether the calculated proportion exceeds the preset proportion value comprises filtering the collected plurality of acceleration data points and discretizing the filtered acceleration data points to obtain discrete data of acceleration and determining whether a proportion of the discrete data exceeding the first acceleration threshold in the preset time window exceeds the preset proportion value.

4. The method according to claim 1 , wherein determining whether the calculated exceeds the preset value comprises low-pass filtering the collected plurality of acceleration data points to obtain filtered acceleration data and determining whether a proportion of the filtered acceleration data exceeding a second acceleration threshold in the preset time window exceeds the preset proportion value.

5. The method according to claim 1 , further comprising controlling the power tool to stop rotation after determining that a kickback occurs in the power tool.

6. The method according to claim 2 , further comprising controlling the power tool to stop rotation after determining that a kickback occurs in the power tool.

7. The method according to claim 3 , further comprising controlling the power tool to stop rotation after determining that a kickback occurs in the power tool.

8. The method according to claim 4 , further comprising controlling the power tool to stop rotation after determining that a kickback occurs in the power tool.

9. A power tool, comprising:
a housing, a power supply module, an electric motor, a control switch, a working portion, an acceleration sensor and a control module, wherein the power supply module, the electric motor, the control switch, the acceleration sensor and the control module are disposed in the housing, the power supply module is electrically connected to the electric motor via the control switch and configured to supply power to the electric motor according to control of the control switch to drive the electric motor to rotate, the electric motor is fixedly connected to the working portion and configured to drive the working portion to rotate when the electric motor is rotating,
the acceleration sensor is configured to detect acceleration along a tangential direction of a rotation axis of the working portion when the working portion is rotating, and the control module is electrically connected to the acceleration sensor and configured to:
collect discrete acceleration data points detected by the acceleration sensor during a preset time window;
calculate a proportion representative of the number of collected acceleration data points that exceeds a first acceleration threshold to the total number of discrete acceleration data points collected;
determine whether the proportion exceeds a preset proportion value; and
determine that a kickback occurs in the power tool when the proportion exceeds the preset proportion value, even when at least one of the discrete acceleration data points detected during the preset time window is below the first acceleration threshold.

10. The power tool according to claim 9 , wherein the detected acceleration is a numeric signal.

11. The power tool according to claim 9 , wherein the control module is further configured to filter the collected acceleration data points and discretize the filtered acceleration data points to obtain discrete data of acceleration and determining whether a proportion of the collected acceleration data that exceeds a first acceleration threshold in a preset time window exceeds a preset value comprises determining whether a proportion of the discrete data exceeding the first acceleration threshold in the preset time window exceeds the preset proportion valued.

12. The power tool according to claim 9 , wherein the control module is further configured to low-pass filter the collected acceleration data points to obtain filtered acceleration data points and determining whether a proportion of the collected acceleration data that exceeds a first acceleration threshold in a preset time window exceeds a preset value comprises determining whether a proportion of the filtered acceleration data exceeding a second acceleration threshold in the preset time window exceeds the preset proportion value.

13. The power tool according to claim 9 , wherein the control module is further configured to control the electric motor to stop rotating or control the power supply module to stop supplying power to the electric motor after determining that the kickback occurs in the power tool.

14. The power tool according to claim 10 , wherein the control module is further configured to control the electric motor to stop rotating or control the power supply module to stop supplying power to the electric motor after determining that the kickback occurs in the power tool.

15. The power tool according to claim 11 , wherein the control module is further configured to control the electric motor to stop rotating or control the power supply module to stop supplying power to the electric motor after determining that the kickback occurs in the power tool.

16. The power tool according to claim 12 , wherein the control module is further configured to control the electric motor to stop rotating or control the power supply module to stop supplying power to the electric motor after determining that the kickback occurs in the power tool.

Assignees

• Nanjing Chervon Ind Co Ltd

Inventors

• Sun Yongan
• Zou Ailong

Classifications

• B25F5/001 Primary

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

• B23Q11/04

  Arrangements preventing overload of tools, e.g. restricting load · CPC title

• B27B9/00

  Portable power-driven circular saws for manual operation (details or components, e.g. handles, casings, of portable power-driven tools not particularly related to the operation performed B25F5/00) · CPC title

• F16P7/02

  by causing the machine to stop on the occurrence of dangerous conditions therein (devices in bearings affected by abnormal conditions F16C) · CPC title

• B25D16/00

  Portable percussive machines with superimposed rotation {, the rotational movement of the output shaft of a motor being modified to generate axial impacts on the tool bit (combined percussion and rotary drilling adapted for earth drilling E21B6/00)} · CPC title