US-12617060-B2 - Power tool control system

US12617060B2US 12617060 B2US12617060 B2US 12617060B2US-12617060-B2

Abstract

A control system for a power tool, comprising: a sensing unit configured to sense an operating characteristic of the power tool; a first control unit configured to determine whether the operating characteristic is within a safe operational range, and to output a first control signal at least partially based on said determination; a second control unit configured to determine whether the operating characteristic is within a safe operational range independently of the first control unit, and to output a second control signal at least partially based on said determination; and an output unit configured to receive the first and second control signals and to activate the power tool when the first and second control signals are received.

Inventors

Yong Min LI
Li Hua XIE
Zhong Kang FANG
Ji Guang SUN

Assignees

TECHTRONIC CORDLESS GP

Dates

Publication Date: 20260505
Application Date: 20241220

Claims (20)

1 . A control system for a power tool, comprising: a sensing unit configured to sense an operating characteristic of the power tool; a first control unit configured to determine whether the operating characteristic is within a first range and to output a first control signal when the operating characteristic is within the first range; a second control unit configured to determine whether the operating characteristic is within a second range independently of the first control unit and to output a second control signal when the operating characteristic is within the second range; and an output unit configured to receive the first and second control signals, activate the power tool when the first and second control signals are received, and maintain activation of the power tool while the first and second control signals are being received.
2 . The control system of claim 1 , wherein the first range and the second range are the same.
3 . The control system of claim 1 , wherein activation of the power tool is disabled if at least one selected from a group consisting of the first signal and the second signal is not received by the output unit.
4 . The control system according to claim 1 , wherein the sensing unit comprises: a first sensor configured to sense the operating characteristic and to output a first sensing signal to the first control unit; and a second sensor configured to sense the operating characteristic independently of the first sensor and to output a second sensing signal to the second control unit.
5 . The control system according to claim 1 , wherein the output unit comprises: a first switching unit configured to activate in response to the first control signal; and a second switching unit configured to activate in response to the second control signal; wherein activation of the first switching unit and second switching unit causes activation of the power tool.
6 . The control system according to claim 5 , wherein the first switching unit and the second switching unit are connected in series.
7 . The control system according to claim 1 , wherein the power tool includes a trigger configured to output a trigger signal to the first control unit and the second control unit simultaneously, and wherein the first control unit is configured to output the first control signal at least partially based on the trigger signal, and the second control unit is configured to output the second control signal at least partially based upon the trigger signal.
8 . The control system according to claim 1 , wherein at least one selected from the group consisting of the first range and the second range corresponds to contact between a nose of the power tool and a workpiece.
9 . The control system according to claim 1 , further comprising a second sensing unit including: a third sensor configured to sense a second operating characteristic; and a fourth sensor configured to sense the second operating characteristic independently of the third sensor; wherein the third sensor is configured to output a third sensing signal to the first control unit and the fourth sensor is configured to output a fourth sensing signal to the second control unit.
10 . The control system according to claim 9 , wherein the second operating characteristic includes at least one selected from a group consisting of a temperature of a prime mover of the power tool and temperature of a PCB of the power tool.
11 . A method of controlling a power tool, comprising: sensing an operating characteristic of a power tool using a sensing unit; determining, via a first control unit, whether the operating characteristic is within a first range and to outputting a first control signal when the operating characteristic is within the first range; determining, via a second control unit separate from the first control unit, whether the operating characteristic is within a second range independently of the first control unit and to outputting a second control signal when the operating characteristic is within the second range; and receiving, via an output unit, the first and second control signals, activating the power tool when the first and second control signals are received, and maintaining activation of the power tool while the first and second control signals are being received.
12 . The method of claim 11 , wherein the first range and the second range are the same.
13 . The method of claim 11 , wherein activation of the power tool is disabled if at least one selected from a group consisting of the first signal and the second signal is not received by the output unit.
14 . The method according to claim 11 , wherein the sensing unit comprises: a first sensor configured to sense the operating characteristic and to output a first sensing signal to the first control unit; and a second sensor configured to sense the operating characteristic independently of the first sensor and to output a second sensing signal to the second control unit.
15 . The method according to claim 11 , wherein the output unit comprises: a first switching unit configured to activate in response to the first control signal; and a second switching unit configured to activate in response to the second control signal; wherein activation of the first switching unit and second switching unit causes activation of the power tool.
16 . The method according to claim 15 , wherein the first switching unit and the second switching unit are connected in series.
17 . The method according to claim 11 , wherein the power tool includes a trigger configured to output a trigger signal to the first control unit and the second control unit simultaneously, and wherein the method further comprising outputting, via the first control unit, the first control signal at least partially based on the trigger signal, and outputting, via the second control unit, the second control signal at least partially based upon the trigger signal.
18 . The method according to claim 11 , wherein at least one selected from the group consisting of the first range and the second range corresponds to contact between a nose of the power tool and a workpiece.
19 . The method according to claim 11 , further comprising: sensing, via a third sensor, a second operating characteristic; and sensing, via a fourth sensor, the second operating characteristic independently of the third sensor; wherein the third sensor is configured to output a third sensing signal to the first control unit and the fourth sensor is configured to output a fourth sensing signal to the second control unit.
20 . The method according to claim 19 , wherein the second operating characteristic includes at least one selected from a group consisting of a temperature of a prime mover of the power tool and temperature of a PCB of the power tool.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. patent application Ser. No. 18/035,465, filed May 4, 2023, which is a 371 Application of PCT/CN2020/126727, filed Nov. 5, 2020, the entire contents of which is hereby incorporated by reference. TECHNICAL FIELD The invention relates to a control system for a power tool, and in particular to a control system having multiple control units for controlling activation of the power tool. The invention also relates to a power tool including the control system. BACKGROUND Power tools typically comprise one or more moving components configured to produce useful work for carrying out a specific task. At least one moving components is typically exposed so as to enable interaction with a workpiece. The exposed component may be translating, oscillating, rotating, or otherwise moving at a high velocity and could therefore cause significant injury to the user upon accidental contact. To reduce the risk of injury to the user, some power tools comprise control systems which monitor one or more safety-critical characteristics of the tool to prevent operation in the event that one or more of the safety-critical characteristics are outside the range of safe operation. The efficacy of such safety control systems may depend upon the robustness of the power tool, the accuracy of the sensors, and the control logic employed by the control system. Over time sensor accuracy may decrease due to wear and tear, which may allow the power tool to be operated under unsafe conditions. Furthermore, the control logic may not account for all possible circumstances under which the power tool can be used, and therefore there may be outlying circumstances in which the control logic will permit operation of the power tool even though it is potentially unsafe to do so. SUMMARY An object in some embodiments of the invention is to provide a power tool, control system and/or method with improved safety. Another object in some embodiments of the invention is to provide a power tool, control system and/or method which obviates or mitigates one or more disadvantages in the prior art, whether identified herein or elsewhere, or provides a useful alternative. Other object(s) of various embodiments of the invention will become apparent by referring to the description and drawings. According to a first aspect of the invention, there is provided a control system for a power tool, comprising: a sensing unit configured to sense an operating characteristic of the power tool; a first control unit configured to determine whether the operating characteristic is within a safe operational range, and to output a first control signal at least partially based on said determination; a second control unit configured to determine whether the operating characteristic is within a safe operational range independently of the first control unit, and to output a second control signal at least partially based on said determination; and an output unit configured to receive the first and second control signals and to activate the power tool when the first and second control signals are received. That is to say, the first control unit outputs the first control signal at least partially based on the determination made by the first control unit and the second control unit outputs the second control signal at least partially based upon the determination made by the second control unit. It will be understood that the first and second control units may be configured to take additional factors into account before outputting their associated control signals, such as for example the status of a trigger or the status of other operating characteristics of the power tool (e.g. temperature etc.). When the control unit receives both the first and the second control signals the control unit will activate the power tool. However, if one of the first or second control signals is not received by the control unit, the power tool will not be activated. Because the first and second control units make their respective determinations separately (i.e. in isolation from one another) the determination of one control unit can be used to verify the determination of the other, and vice versa. As such, the control system is able to prevent activation of the power tool in the event that the determination by one of the control units that the power tool is safe to activate cannot be corroborated by the second control unit. This “double check” ensures that physical malfunctions, for example in the sensing unit, or logical malfunctions, for example in the first and second controllers themselves, are more likely to be identified and any associated unsafe activation of the power tool prevented. Activation of the power tool will be understood to encompass operating the power tool to produce useful work. This may include, for example, the activation of a prime mover (e.g., motor), actuation of a solenoid, the creation of an electrical arc a