Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25F—COMBINATION OR MULTI-PURPOSE TOOLS NOT OTHERWISE PROVIDED FOR; DETAILS OR COMPONENTS OF PORTABLE POWER-DRIVEN TOOLS NOT PARTICULARLY RELATED TO THE OPERATIONS PERFORMED AND NOT OTHERWISE PROVIDED FOR
  • B25F5/00—Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for

Definitions

• the present disclosure relates to power tools and, in particular, to controlling a power in a way which mitigates the danger from kickback.
• a self-locking tool causes the tool to continue running even if the user releases the input control, e.g. input trigger. This can cause harm if, for example, the user sets down the tool after using it, without releasing the self-locking function. In this situation, the tool can continue running and may cause damage or harm to the user.
• kickback can be caused by wood knots or foreign objects in a work piece.
• the sudden stopping of the working component can result in a large torque suddenly being transmitted to the body of the power tool, and to the user.
• kickback can cause the user to inadvertently release the power tool. This has the potential to cause damage or harm from the working component of the tool or the spinning body or the tool itself.
• an anti-kickback module for a power tool which includes an accelerometer arranged to detect components of acceleration of the power tool, a power controller configured to control an operational state of the power tool, and a processor configured to determine a kickback state of the power tool based on a change in at least one component of acceleration of the power tool, and instruct the power controller to cease operation of the power tool in response to determining the kickback state.
• Determining the kickback state may include determining that the change in at least one component of acceleration of the power tool is above a predefined threshold value.
• Determining the kickback state may include determining that a rate of change in at least one component of acceleration of the power tool is above a predefined rate threshold.
• the components of acceleration may be measured along any three non-parallel axes.
• the processor may be configured to instruct the power controller to actively decelerate a motor of the power tool in response to determining the kickback state.
• the processor may be configured to instruct the power controller to apply a preselected braking profile to actively decelerate the motor of the power tool.
• the anti-kickback module may include an active braking mechanism.
• the processor may be configured to activate the active braking mechanism in response to determining the kickback state.
• a power tool comprising the anti-kickback module.
• a method of controlling operation of a power tool which includes detecting components of acceleration of the power tool using an accelerometer, determining a kickback state of the power tool based on a change in at least one component of acceleration of the power tool, and instructing a power controller to cease operation of the power tool in response to determining the kickback state.
• Determining the kickback state may include determining that the change in at least one component of acceleration of the power tool is above a predefined threshold value.
• Determining the kickback state may include determining that a rate of change in at least one component of acceleration of the power tool is above a predefined rate threshold.
• the components of acceleration may be measured along any three non-parallel axes.
• the method may include instructing the power controller to actively decelerate a motor of the power tool in response to determining the kickback state.
• the method may include instructing the power controller to apply a preselected braking profile to actively decelerate the motor of the power tool.
• the method may include activating an active braking mechanism in response to determining the kickback state.
• Fig. 1 a schematic diagram of an anti-kickback module 1 for a power tool, according to an embodiment.
• the anti-kickback module 1 includes an accelerometer 10, a power controller 20, and a processor 30.
• the accelerometer 10 is arranged to detect components of acceleration of the power tool.
• the accelerometer 10 may be configured to detect 1 to 3 components of acceleration.
• the components of acceleration may be measured along any non-parallel axes.
• the accelerometer 10 may be a 3-axis acceleration sensor, configured to measure acceleration along 3 perpendicular axes.
• the accelerometer 10 may be a 6-axis acceleration and rotation sensor.
• the power controller 20 is configured to control an operational state of the power tool.
• the power controller 20 may be configured to activate or deactivate the power tool.
• the power controller 20 may activate or deactivate the power tool in response to a user control, for example, using a power button or trigger actuator.
• the power controller 20 may control a power supply to a motor of the power tool.
• the power controller 20 may control the power supply from a battery pack to the motor.
• the power controller 20 may control the motor speed.
• the power controller 20 may control the motor speed in response to a user control, for example, using a speed control trigger.
• the processor 30 is configured to determine a kickback state of the power tool based on a change in at least one component of acceleration of the power tool.
• the processor 30 may be configured to detect an acceleration indicating that the power tool is out of the user's hand. Detection of a hands-off state of the power tool may indicate the power tool is in the kickback state.
• the processor 30 is configured to instruct the power controller 20 to cease operation of the power tool in response to determining the kickback state.
• the anti-kickback module 1 can trigger anti-kickback protection if the tool is detected to be out of hand when the tool is running.
• This anti-kickback protection can cease the operation of the power tool, reducing the risk of injury cause by a kickback state of the power tool.
• the speed of the power tool can be reduced or stopped more quickly than the user is able to deactivate the tool, and often before the user realises the kickback has occurred.
• the anti-kickback module 1 can increase the safety of operation of the power tool.
• the anti-kickback module 1 can reduce the potential harm caused by dangerous kickback events.
• the anti-kickback module 1 can reduce the potential harm caused by any release of the tool when running, for example, setting the tool down when the tool is locked on.
• Determining the kickback state may include determining that the change in at least one component of acceleration of the power tool is above a predefined threshold value.
• Figure 2 is a chart showing an accelerometer output for an exemplary embodiment.
• the power tool may be in a normal state, for example, the power tool is in normal use or at rest.
• the accelerometer 10 may output a stable acceleration with little change.
• the processor 30 may be configured to detect when the power tool is in a steady state.
• the processor 30 may detect that the acceleration is constant or substantially constant to within a threshold for a predefined period of time.
• the processor 30 may detect that the acceleration does not change by more than, e.g. 5% or 10%, within the predefined period of time.
• the predefined period of time may be between 0.1s and 1s.
• the processor 30 may calibrate set parameters for the normal state when the steady state is detected.
• the set parameters may include baseline acceleration values for one or more of the components of acceleration.
• the power tool may experience a kickback event. For example, a working component of the tool may contact with a foreign object in a work piece and suddenly stop spinning.
• the processor 30 may be configured to detect an acceleration change between 1G and 4G.
• the acceleration change may be detected for one or more of the components of acceleration.
• the acceleration change may be measured with respect to the baseline acceleration values for the steady state.
• the acceleration change may be a threshold acceleration delta which occurs within a predefined time window.
• the predefined time window may be from 50ms to 500ms. More specifically, the predefined time window may be 200ms.
• Determining the kickback state may include determining that a rate of change in at least one component of acceleration of the power tool is above a predefined rate threshold.
• the predefined rate threshold may be between 2G/s to 80G/s.
• the processor 30 may be configured to detect when the component of acceleration of the power tool is above the predefined rate threshold for a predefined period of time. For example, the predefined period of time may be between 0.1s and 1s.
• the processor 30 may be configured to instruct the power controller 20 to actively decelerate a motor of the power tool in response to determining the kickback state.
• the power controller 20 may be configured to transmit signals which are out of sync with the rotation of the motor and cause the magnetic elements of the motor to act in opposition to the motion of the motor, decelerating the motor.
• the signals transmitted to the motor may be selected from a plurality of signals which correspond to different braking profiles e.g. to cause faster or slower braking of the power tool.
• the processor 30 may be configured to instruct the power controller 20 to apply a preselected braking profile to actively decelerate the motor of the power tool. For example, where the power tool is configured to employ a certain braking profile in normal use (e.g. when the power tool trigger is released), the power controller 20 may be configured to select a faster profile in response to determining the kickback state. In this way, the power tool may be braked more quickly in an emergency situation.
• a particular braking profile may be also selected based on the 3-axis sensor e.g. a faster braking profile may be selected if a particularly dangerous motion is detected.
• the anti-kickback module 1 may include an active braking mechanism.
• the processor 30 may be configured to activate the active braking mechanism in response to determining the kickback state.
• the active braking mechanism may include a friction component e.g. including one or more brake pads arranged to make contact with a moving component of the power tool such as the disc of an angle grinder.
• the active braking mechanism may include a blocking component e.g. an element which physically obstructs the moving component of the power tool.
• the active braking mechanism may be designed for single-use e.g. due to damaged caused to the power tool or the active braking mechanism itself, or may be used multiple times.
• the anti-kickback module 1 may be configured to provide additional protection e.g. to cease operation of the power tool in the event of a drop or fall.
• the processor 30 may be configured to recognise an acceleration profile for a dropped tool, e.g. a period of free-fall followed by an impact.
• the period of free-fall may be identified by an acceleration value at or close to zero.
• the impact may be identified by a sudden change in acceleration from the value which is close to zero.
• a supply voltage of the accelerometer 10 may be in the range of 1.5V to 5V, and more specifically in the range of 1.62V to 3.6V.
• the accelerometer 10 may operate in a range of, for example, ⁇ 2g, ⁇ 4g, ⁇ 8g or ⁇ 16g. In some examples, the range may be user selectable, so as to configure the fall detection module 10. In some examples, a resolution of the accelerometer 10 may be 14 bits, or may be any suitable value e.g. selected in a range of 8 - 32 bits. In some examples, a data output rate of the accelerometer 10 may be in a range from 1Hz to 1000Hz.
• the accelerometer 10 may be placed as far away from the motor as possible. In this way, it is possible to reduce the impact of the vibration of the power tool itself on the accelerometer 10.
• the accelerometer 10 may be placed at a base of the power tool e.g. where the power tool is connected with a battery pack.
• the accelerometer 10 may be implemented in a package having a size of 2x2x0.9mm.
• the kickback module may be provided as part of the power tool. Alternatively, in some implementations the kickback module may be provided separately.
• a separate module may be connected with a control logic board of the tool e.g. through an available bus connection.
• the module may be configured to interface with the battery pack or battery connection, in order to interrupt the power supply in the event of a kickback state.
• FIGS 3A and 3B are schematic diagrams of power tools including the anti-kickback module 1 of any embodiment.
• FIG 3A is a schematic diagram showing an electric power tool 100 according to an embodiment.
• the power tool is a handheld chainsaw comprising a blade and chain as a working component 110, a motor 120, and an anti-kickback module 1, substantially as described above.
• FIG. 3B is a schematic diagram showing an electric power tool 200 according to an embodiment.
• the power tool is a handheld power drill comprising a chuck as a working component 210, a motor 220, and an anti-kickback module 1, substantially as described above.
• the power tool may be embodied as, for example, a circular saw, a reciprocal saw, a jig saw, a hedge trimmer, string trimmer, lawnmower, or any other suitable tool.
• FIG. 4 is a flowchart showing a method of controlling operation of a power tool, according to an embodiment. The method starts at step S01.
• step S02 components of acceleration of the power tool are detected using an accelerometer.
• a kickback state of the power tool is determined based on a change in at least one component of acceleration of the power tool.
• a power controller is instructed to cease operation of the power tool in response to determining the kickback state.
• the present technology may be presented as including individual functional blocks including functional blocks comprising devices, device components, steps or routines in a method embodied in software, or combinations of hardware and software.
• Such instructions can comprise, for example, instructions and data which cause or otherwise configure a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions. Portions of computer resources used can be accessible over a network.
• the computer executable instructions may be, for example, binaries, intermediate format instructions such as assembly language, firmware, or source code. Examples of computer-readable media that may be used to store instructions, information used, and/or information created during methods according to described examples include magnetic or optical disks, flash memory, Universal Serial Bus (USB) devices provided with non-volatile memory, networked storage devices, and so on.
• USB Universal Serial Bus
• Devices implementing methods according to these disclosures can comprise hardware, firmware and/or software, and can take any of a variety of form factors. Typical examples of such form factors include laptops, smart phones, small form factor personal computers, personal digital assistants, and so on. Functionality described herein also can be embodied in peripherals or addin cards. Such functionality can also be implemented on a circuit board among different chips or different processes executing in a single device, by way of further example.
• the instructions, media for conveying such instructions, computing resources for executing them, and other structures for supporting such computing resources are means for providing the functions described in these disclosures.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Portable Power Tools In General (AREA)
• Percussive Tools And Related Accessories (AREA)

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Citations (7)

• 2024
  • 2024-03-07 EP EP24161910.5A patent/EP4613431A1/de active Pending
• 2025
  • 2025-01-21 CN CN202510094649.2A patent/CN120606356A/zh active Pending
  • 2025-02-03 AU AU2025200724A patent/AU2025200724A1/en active Pending

Patent Citations (7)

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