Anti-kickback power tool control
First Claim
1. In a power tool of the type having an implement driven by a motive power source, the improvement of a system for detecting an impending kickback condition in the power tool comprising:
- (a) monitoring means for monitoring the speed of a predetermined part of the power tool;
(b) means connected to said monitoring means for determining the rate of change of the monitored speed; and
(c) means for producing a predetermined response when said rate of change attains a determinable value.
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Accused Products
Abstract
An impending kickback condition is the operation of a power tool or machine tool system is sensed and used to control or eliminate the kickback. The ability to sense an impending kickback condition can be used in all categories of power driven tools. The change in force applied to the power driven tool or other implement is monitored by measuring the rate of change of speed of the tool or implement, and if the speed is decreasing, the rate of change of speed is compared with a threshold value which may be either preset or variable. If this threshold value is exceeded, an output control signal is generated which inhibits the coupling of power to the tool or other implement and/or applies a brake to stop the tool or implement. In order for power to once again be coupled from the motive power source to the shaft, the start switch must be opened and then reclosed or some other signal provided by the operator or another predetermined condition must be met.
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Citations
46 Claims
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1. In a power tool of the type having an implement driven by a motive power source, the improvement of a system for detecting an impending kickback condition in the power tool comprising:
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(a) monitoring means for monitoring the speed of a predetermined part of the power tool; (b) means connected to said monitoring means for determining the rate of change of the monitored speed; and (c) means for producing a predetermined response when said rate of change attains a determinable value.
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2. In a power tool of the type having an implement driven by a motive power source, the improvement of a system for detecting an impending kickback condition in the power tool comprising:
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(a) monitoring means for monitoring the speed of a predetermined part of the power tool; (b) means connected to said monitoring means for determining the rate of change of the monitored speed; (c) comparing means for comparing the rate of change of the monitored speed with a threshold to detect an impending kickback condition. - View Dependent Claims (3, 4, 5)
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6. In a power tool of the type having an implement driven by a motive power source, the improvement of an anti-kickback control system for said power tool comprising:
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(a) monitoring means for generating a signal proportional to the speed of a predetermined part of the power tool; (b) determining means connected to receive the signal generated by said monitoring means for developing a signal proportional to the rate of change of the signal from said monitoring means; (c) comparing means connected to receive the signals developed by said measuring means and a threshold signal for producing an output signal whenever the signal developed by said measuring means exceeds said threshold signal; and (d) control means set by the output signal of said comparing means for inhibiting the supply of power to said implement. - View Dependent Claims (7, 8, 9)
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10. In a power tool of the type having a rotary shaft connected to drive an implement and an electric motor coupled to said rotary shaft to impart a rotary motion thereto, said electric motor being adapted to be connected to a source of electrical power through a switching device, the improvement of an anti-kickback control system comprising:
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(a) monitoring means for monitoring the speed of rotation of said rotary shaft; (b) means connected to said monitoring means for measuring the rate of change of the speed of the rotation of said rotary shaft; (c) comparing means for comparing the measured rate of change of the speed of rotation of said rotary shaft with a threshold; and (d) means connected to said comprising means for controlling said switching device to block the connection of electrical power to said electric motor if the measured rate of change of the speed of rotation of said rotary shaft exceeds said threshold.
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11. In a power tool of the type having a rotary shaft connected to drive an implement and a pneumatic motor couple to said rotary shaft to impart a rotary motion thereto, said pneumatic motor being adapted to be connected to a source of compressed air through a valve, the improvement of an anti-kickback control system comprising:
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(a) monitoring means for monitoring the speed of rotation of said rotary shaft; (b) means connected to said monitoring means for measuring the rate of change of the speed of rotation of said rotary shaft; (c) comparing means for comparing the measured rate of change of the speed of rotation of said rotary shaft with a threshold; and (d) means connected to said comprising means for operating said valve to block the coupling of compressed air to said pneumatic motor if the measured rate of change of the speed of rotation of said rotary shaft exceeds said threshold.
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12. In a power tool of the type having a rotary shaft connected to drive an implement and an internal combustion engine coupled to said rotary shaft to impart a rotary motion thereto, said internal combustion engine being coupled to said rotary shaft by means of a clutch, the improvment of an anti-kickback control system comprising:
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(a) monitoring means for monitoring the speed of rotation of said rotary shaft; (b) means connected to said monitoring means for measuring the rate of change of the speed of rotation of said rotary shaft; (c) comparing means for comparing the measured rate of change of the speed of rotation of said rotary shaft with a threshold; and (d) means connected to said comparing means for operating said clutch to disengage the coupling of power from said internal combustion engine to said rotary shaft if the measured rate of change of the speed of rotation of said rotary shaft exceeds said threshold. - View Dependent Claims (13)
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14. In a power tool of the type having a rotary shaft connected to drive an implement and a motive power source coupled to said rotary shaft to impart a rotary motion thereto, the improbement of an anti-kickback control system comprising:
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(a) a switch which, when closed, generates a reset signal for enabling the supply of power to said rotary shaft from said motive power source; (b) monitoring means for monitoring the speed of rotation of said rotary shaft to develop a first signal proportional to the speed of rotation of said rotary shaft; (c) means connected to said monitoring means for generating a second signal proportional to the rate of change of said first signal; (d) comparing means for comparing said second signal with a threshold signal and developing an output signal whenever said second signal exceeds said threshold signal; and (e) means connected to said comparing means for generating a set signal to inhibit the supply of power to said rotary shaft whenever said output signal is developed. - View Dependent Claims (15)
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16. In a power tool of the type having a rotary shaft connected to an implement and an electric motor coupled to said rotary shaft to impart a rotary motion thereto, said electric motor being adapted to be connected to a source of electrical power through a switching device, the improvement of an anti-kickback control system comprising:
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(a) a switch, which when closed, generates a reset signal to said switching device to cause said switching device to connect electrical power to said electric motor; (b) monitoring means for monitoring the speed of rotation of said rotary shaft to develop a first signal proportional to the speed of rotation of said rotary shaft; (c) means connected to said monitoring means for generating a second signal proportional to the rate of change of said first signal; (d) comparing means for comparing said second signal with a threshold signal for developing an output signal whenever said signal exceeds said threshold signal; and (e) means connected to said comparing means for generating a set signal to said switching device to cause said switching device to block power to said electric motor in response to said output signal. - View Dependent Claims (17)
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18. In a power tool of the type having a rotary shaft connected to an implement and a pneumatic motor coupled to said rotary shaft to impart a rotary motion thereto, said pneumatic motor being adapted to be connected to a source of compressed air through a solenoid operated valve, the improvement of an anti-kickback control system comprising:
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(a) a switch to generate a reset signal to said solenoid operated valve to cause said valve to couple compressed air to said pneumatic motor; (b) monitoring means for monitoring the speed of rotation of said rotary shaft to develop a first signal proportional to the speed of rotation of said rotary shaft; (c) means connected to said monitoring means for generating a second signal proportional to the rate of change of said first signal; (d) comparing means for comparing said second signal with a threshold signal and developing an output signal whenever said second signal exceeds said threshold signal; and (e) means connected to said comparing means for generating a set signal to said solenoid operated valve to cause said valve to block compressed air to said pneumatic motor in response to said output signal. - View Dependent Claims (19)
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20. In a power tool of the type having a rotary shaft connected to an implement and an internal combustion engine coupled to said rotary shaft to impart a rotary motion thereto, said internal combustion engine being coupled to said rotary shaft by means of a solenoid operated clutch, the improvement of an anti-kickback control system comprising:
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(a) a switch which, when closed, generates a reset signal to said solenoid operated clutch to cause said clutch to couple power from said internal combustion engine to said rotary shaft; (b) monitoring means for monitoring the speed of rotation of said rotary shaft to develop a first signal proportional to the speed of rotation of said rotary shaft; (c) means connected to said monitoring for generating a second signal proportional to the rate of change of said first signal; (d) comparing means for comprising said second signal with a threshold signal and developing an output signal whenever said signal exceeds said threshold signal; and (e) means connected to said comparing means for generating a set signal to said solenoid operated clutch to cause said clutch to disengage the coupling of power from said internal combustion engine to said rotary shaft in response to said output signal. - View Dependent Claims (21, 22)
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23. In a power tool of the type having an implement driven by a motive power source, the improvement of an anti-kickback control system for said power tool comprising:
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(a) monitoring means for monitoring a signal proportional to the speed of a predetermined part of the power tool; (b) a microprocessor connected to receive the signal from said monitoring means, said microprocessor being programmed to compute the rate of change of the signal from said monitoring means, compare the computed rate of change with a threshold value, and produce an inhibit output signal whenever the computed rate of change exceeds said threshold value; and (c) control means responsive to said inhibit output signal for inhibiting the supply of power to said implement. - View Dependent Claims (24)
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25. In a power tool of the type having a rotary shaft connected to drive an implement and an electric motor coupled to said rotary shaft to impart a rotary motion thereto, said electric motor being adapted to be connected to a source of electrical power through a switching device, the improvement of an anti-kickback control system for said power tool comprising:
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(a) a pulse generator for generating pulses having a frequency proportional to the speed of rotation of said rotary shaft; (b) a microprocessor connected to receive the pulses from said pulse generator, said microprocessor being programmed to compute the speed of rotation of said rotary shaft as a function of elapsed time between pulses from said pulse generator, compute the rate of change of the speed of rotation of said rotary shaft as a function of the difference between elapsed time intervals between successive pulse intervals, compare the computed rate of change with a threshold value, and produce an inhibit output signal whenever the computed rate of change exceeds said threshold value; and (c) control means responsive to said inhibit output signal for controlling said switching device to block the connection of electrical power to said electric motor.
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26. A method of detecting an impending kickback condition in a power tool of the type having an implement driven by a motive power source, the method comprising the steps of:
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(a) monitoring the speed of a predetermined part of the power tool; (b) determining the rate of change of the monitoring speed; and (c) producing a predetermined response when said rate of change attains a determinable value.
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27. A method of detecting an impending kickback condition in a power tool of the type having an implement driven by a motive power source, the method comprising the steps of:
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(a) monitoring the speed of a predetermined part of the power tool; (b) determining the rate of change of the monitored speed; (c) comparing the rate of change of the monitored speed to a determinable threshold; and (d) producing a predetermined response when said rate of change bears a predetermined relationship to said threshold. - View Dependent Claims (28, 29, 30, 31)
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32. A method of eliminating kickback in a power tool of the type having an implement driven by a motive power source, the method comprising the steps of:
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(a) monitoring the speed of a predetermined part of the power tool; (b) determining the rate of change of the monitoring speed; (c) comparing the rate of change of the monitored speed with a threshold; and (d) inhibiting the supply of power to said tool if the rate of change of the monitored speed exceeds said threshold. - View Dependent Claims (33)
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34. A method of eliminating kickback in a power tool of the type having a rotary shaft connected to drive an implement and an electric motor coupled to said rotary shaft to impart a rotary motion thereto, said electric motor being adapted to be connected to a source of electrical power through a switching device, the method comprising the steps of:
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(a) monitoring the speed of rotation of said rotary shaft; (b) measuring the rate of change of the speed of rotation of said rotary shaft; (c) comparing the measured rate of change of the speed of rotation of said rotary shaft with a threshold; and (d) controlling said switching device to block the connection of electrical power to said electric motor if the measured rate of change of the speed of rotation of said rotary shaft exceeds said threshold.
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35. A method of eliminating kickback in a power tool of the type having a rotary shaft connected to drive an implement and a pneumatic motor coupled to said rotary shaft to impart a rotary motion thereto, said pneumatic motor being adapted to be connected to a source of compressed air through a valve, the method comprising the steps of:
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(a) monitoring the speed of rotation of said rotary shaft; (b) measuring the rate of change of the speed of rotation of said rotary shaft; (c) comparing the measured rate of change of the speed of rotation of said rotary shaft with a threshold; and (d) operating said valve to block the coupling of compressed air to said pneumatic motor if the measured rate of change of the speed of rotation of said rotary shaft exceeds said threshold.
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36. A method of eliminating kickback in a power tool of the type having a rotary shaft connected to drive an implement and an internal combustion engine coupled to said rotary shaft to impart a rotary motion thereto, said internal combustion engine being coupled to said rotary shaft by means of a clutch, the method comprising the steps of:
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(a) monitoring the speed of rotation of said rotary shaft; (b) measuring the rate of change of the speed of rotation of said rotary shaft; (c) comparing the measured rate of change of the speed of rotation of said rotary shaft with a threshold; and (d) operating said clutch to disengage the coupling of power from said internal combustion engine to said rotary shaft if the measured rate of change of the speed of rotation of said rotary shaft exceeds said threshold. - View Dependent Claims (37)
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38. A method of eliminating kickback in a power tool of the type having a rotary shaft connected to drive an implement and a motive power source coupled to said rotary shaft to impart a rotary motion thereto, said method comprising the steps of:
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(a) closing a switch to generate a reset signal for enabling the coupling of power to said rotary shaft from said motive power source; (b) monitoring the speed of rotation of said rotary shaft to develop a first signal proportional to the speed of rotation of said rotary shaft; (c) generating a second signal proportional to the rate of change of said first signal; (d) comparing said second signal with a threshold signal and developing an output signal whenever said second signal exceeds said threshold signal; and (e) generating a set signal to inhibit the coupling of power to said rotary shaft from said motive power source whenever said output signal is developed. - View Dependent Claims (39)
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40. A method of eliminating kickback in a power tool of the type having a rotary shaft connected to an implement and an electric motor coupled to said rotary shaft to impart a rotary motion thereto, said electric motor being adapted to be connected to a source of electrical power through a switching device, the method comprising the steps of:
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(a) closing a switch to generate a reset signal to said switching device to cause said switching device to connect electrical power to said electric motor; (b) monitoring the speed of rotation of said rotary shaft to develop a first signal proportional to the speed of rotation of said rotary shaft; (c) generating a second signal proportional to the rate of change of said first signal; (d) comparing said second signal with a threshold signal and developing an output signal whenever said second signal exceeds said threshold signal; and (e) generating a set signal to said switching device to cause said switching device to block power to said electric motor in response to said output signal. - View Dependent Claims (41)
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42. A method of eliminating kickback in a power tool of the type having a rotary shaft connected to an implement and a pneumatic motor coupled to said rotary shaft to impart a rotary motion thereto, said pneumatic motor being adapted to be connected to a source of compressed air through a solenoid operated valve, the method comprising the steps of:
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(a) closing a switch to generate a reset signal to said solenoid operated valve to cause said valve to couple compressed air to said pneumatic motor; (b) monitoring the speed of rotation of said rotary shaft to develop a first signal proportional to the speed of rotation of said rotary shaft; (c) generating a second signal proportional to the rate of change of said first signal; (d) comparing said second signal with a threshold signal and developing an output signal whenever said second signal exceeds said threshold signal; and (e) generating a set signal to said solenoid operated valve to cause said valve to block compressed air to said pneumatic motor in response to said output signal. - View Dependent Claims (43)
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44. A method of eliminating kickback in a power tool of the type having a rotary shaft connected to an implement and an internal combustion engine coupled to said rotary shaft to impart a rotary motion thereto, said internal combustion engine being coupled to said rotary shaft by means of a solenoid operated clutch, the method comprising the steps of:
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(a) closing a switch to generate a reset signal to said solenoid operated clutch to cause said clutch to couple power from said internal combustion engine to said rotary shaft; (b) monitoring the speed of rotation of said rotary shaft to develop a first signal proportional to the speed of rotation of said rotary shaft; (c) generating a second signal proportional to the rate of change of said first signal; (d) comparing said second signal with a threshold signal and developing an output signal whenever said second signal exceeds said threshold signal; and (e) generating a set signal to said solenoid operated clutch to cause said clutch to disengage the coupling of power from said internal combustion engine to said rotary shaft in response to said output signal. - View Dependent Claims (45, 46)
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Specification