US4249117A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Anti-kickback power tool control
Assignee: Black and Decker Inc
•
Filing: 1979-05-01
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Granted: 1981-02-03
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Expires: 1999-05-01
Abstract
Abstract An impending kickback condition in 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 with a microcomputer by measuring the rate of change of current. If the current is increasing, the microcomputer compares the rate of change of current with a threshold value which may be either preset or computed by the microcomputer. If this threshold value is exceeded, an output control signal is generated by the microcomputer 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 to the tool or implement, the start switch must be opened and then reclosed or some other signal provided by the operator or another predetermined condition must be fulfilled.
Inventors
- 👤 Jill L. Leukhardt
- 👤 David A. Saar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 16:00
CPC Classifications
H; H02; H02H; H02H7/00; H02H7/08; H02H7/085; H02H7/0854; B; B23; B23D; B23D59/00; B23D59/008; B23Q; B23Q11/00; B23Q11/04; B27; B27B; B27B5/00; B27B5/29; B27B5/38; F; F16; F16P; F16P3/00; G; G01; G01P; G01P3/00; G01P3/42; G01P3/44; G01P3/48; G01P3/481; G01P3/489
Claims Analysis
Total Claims: 43
Claim 1
Independent Claim
95 words
A method of detecting an impending kickback condition in a power tool of the type having an implement driven by an electric motor, said electric motor being supplied with current from an AC source, the method comprising the steps of: (a) sampling successive periods of the current through said motor at determinate points in the current waveform; (b) filtering the sampled values of motor current; (c) measuring the rate of change of the results of said step of filtering; (d) comparing the measured rate of change with a threshold to detect an impending kickback condition.
Claim 2
Independent Claim
95 words
A method of detecting an impending kickback condition in a power tool of the type having an implement driven by an electric motor, said electric motor being supplied with current from an AC source, the method comprising the steps of: (a) sampling successive periods of the current through said motor at determinate points in the current waveform; (b) filtering the sampled values of motor current; (c) measuring the rate of change of the results of said step of filtering; (d) comparing the measured rate of change with a threshold to detect an impending kickback condition.
Claim 3
Dependent Claim
42 words
The method of detecting an impending kickback condition as recited in claim 1 wherein the current samples taken in said step of sampling are taken in the vicinity of the peak current value during at least each cycle of said AC source.
Claim 4
Dependent Claim
60 words
The method of detecting an impending kickback condition as recited in claim 1 wherein said electric motor is supplied with current from said AC source through an electronic switching circuit which is turned on each half cycle of said AC source, the step of sampling being performed at a time measured from when said electronic switching current is turned on.
Claim 5
Dependent Claim
24 words
The method of detecting an impending kickback condition as recited in claim 1 wherein said step of filtering is performed by averaging the samples.
Claim 6
Dependent Claim
21 words
The method of detecting an impending kickback condition as recited in claim 1 further comprising the step of setting said threshold.
Claim 7
Independent Claim
105 words
A method of eliminating kickback in a power tool of the type having an implement driven by an electric motor, said electric motor being supplied with current from an AC source, the method comprising the steps of: (a) sampling successive periods of the current through said motor at determinate points in the current waveform; (b) filtering the sampled values of motor current; (c) measuring the rate of change of the results of said step of filtering; (d) comparing the measured rate of change with a threshold; and (e) inhibiting the supply of current to said motor if the measured rate of change exceeds said threshold.
Claim 8
Independent Claim
105 words
A method of eliminating kickback in a power tool of the type having an implement driven by an electric motor, said electric motor being supplied with current from an AC source, the method comprising the steps of: (a) sampling successive periods of the current through said motor at determinate points in the current waveform; (b) filtering the sampled values of motor current; (c) measuring the rate of change of the results of said step of filtering; (d) comparing the measured rate of change with a threshold; and (e) inhibiting the supply of current to said motor if the measured rate of change exceeds said threshold.
Claim 9
Dependent Claim
43 words
The method of eliminating kickback in a power tool as recited in claim 6 wherein the current samples taken in said step of sampling are taken in the vicinity of the peak current value during at least each cycle of said AC source.
Claim 10
Dependent Claim
61 words
The method of eliminating kickback in a power tool as recited in claim 6 wherein said electric motor is supplied with current from said AC source through an electronic switching circuit which is turned on each half cycle of said AC source, the step of sampling being performed at a time measured from when said electronic switching circuit is turned on.
Claim 11
Dependent Claim
25 words
The method of eliminating kickback in a power tool as recited in claim 6 wherein said step of filtering is performed by averaging the samples.
Claim 12
Dependent Claim
43 words
The method of eliminating kickback in a power tool as recited in claim 6 further comprising the step of applying a brake to stop the motion of said tool or other implement if the measured rate of change of current exceeds said threshold.
Claim 13
Dependent Claim
22 words
The method of eliminating kickback in a power tool as recited in claim 6 further comprising the step of setting said threshold.
Claim 14
Independent Claim
136 words
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 periodically supplied with current through an electronic switching circuit, the method comprising the steps of: (a) sampling successive periods of the current through said motor at determinate points in the current waveform generated by said electronic switching circuits; (b) filtering the sampled values of motor current; (c) measuring the rate of change of the results of said step of filtering; (d) comparing the measured rate of change with a threshold; and (e) controlling said electronic switching circuit to block the supply of current to said electric motor if the measured rate of change exceeds said threshold.
Claim 15
Independent Claim
136 words
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 periodically supplied with current through an electronic switching circuit, the method comprising the steps of: (a) sampling successive periods of the current through said motor at determinate points in the current waveform generated by said electronic switching circuits; (b) filtering the sampled values of motor current; (c) measuring the rate of change of the results of said step of filtering; (d) comparing the measured rate of change with a threshold; and (e) controlling said electronic switching circuit to block the supply of current to said electric motor if the measured rate of change exceeds said threshold.
Claim 16
Dependent Claim
42 words
The method of eliminating kickback in a power tool as recited in claim 12 wherein said electronic switching circuit is periodically turned on, the step of sampling being performed at a time measured from when said electronic switching circuit is turned on.
Claim 17
Dependent Claim
39 words
The method of eliminating kickback in a power tool as recited in claim 12 wherein the current samples are taken in the vicinity of the peak current value during the periods when said electronic switching circuit is turned on.
Claim 18
Dependent Claim
25 words
The method of eliminating kickback in a power tool as recited in claim 12 wherein the step of filtering is performed by averaging the samples.
Claim 19
Independent Claim
156 words
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 supplied with current through an electric switching circuit, the method comprising the steps of: (a) closing a switch to generate a signal to said electronic switching circuit to cause said electric switching circuit to periodically supply current to said electric motor; (b) sampling successive periods of the current through said motor at determinate points in the current waveform; (c) filtering the sampled values of motor current; (d) measuring the rate of change of the results of said step of filtering; (e) comparing the measured rate of change with a threshold; and (f) controlling said electronic switching circuit to block the supply of current to said electric motor if the measured rate of change exceeds said threshold.
Claim 20
Independent Claim
156 words
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 supplied with current through an electric switching circuit, the method comprising the steps of: (a) closing a switch to generate a signal to said electronic switching circuit to cause said electric switching circuit to periodically supply current to said electric motor; (b) sampling successive periods of the current through said motor at determinate points in the current waveform; (c) filtering the sampled values of motor current; (d) measuring the rate of change of the results of said step of filtering; (e) comparing the measured rate of change with a threshold; and (f) controlling said electronic switching circuit to block the supply of current to said electric motor if the measured rate of change exceeds said threshold.
Claim 21
Dependent Claim
59 words
The method of eliminating kickback in a power tool as recited in claim 16 further comprising the step of opening and closing said switch after the supply of current to said electric motor has been blocked to again generate a signal to said electronic switching circuit to cause said electronic switching circuit to supply current to said electric motor.
Claim 22
Dependent Claim
136 words
In a power tool of the type having an implement driven by an electric motor, said electric motor being supplied with current from an AC source, the improvement of a system for detecting an impending kickback condition in the power tool comprising: (a) sampling means for sampling successive periods of the current through said motor at determinate points in the current waveform; (b) filtering means for filtering the sampled values from said sampling means; (c) means connected to said filtering means for storing the results of filtering successive sampled values of motor current and for computing the difference between the stored results as a measure of the rate of change of said results of filtering; (d) comparing means for comparing said measure of the rate of change with a threshold to detect an impending kickback condition.
Claim 23
Dependent Claim
136 words
In a power tool of the type having an implement driven by an electric motor, said electric motor being supplied with current from an AC source, the improvement of a system for detecting an impending kickback condition in the power tool comprising: (a) sampling means for sampling successive periods of the current through said motor at determinate points in the current waveform; (b) filtering means for filtering the sampled values from said sampling means; (c) means connected to said filtering means for storing the results of filtering successive sampled values of motor current and for computing the difference between the stored results as a measure of the rate of change of said results of filtering; (d) comparing means for comparing said measure of the rate of change with a threshold to detect an impending kickback condition.
Claim 24
Dependent Claim
48 words
The improvement of a system for detecting an impending kickback condition in a power tool as recited in claim 18 wherein said means for sampling takes a plurality of current samples in the vicinity of the peak current value during at least each cycle of said AC source.
Claim 25
Dependent Claim
77 words
The improvement of a system for detecting an impending kickback condition in a power tool as recited in claim 18 wherein said electric motor is supplied with current from said AC source through an electronic switching circuit which is turned on each half cycle of said AC source, said sampling means including timing means to control the taking of a plurality of current samples at a time measured from when said electronic switching circuit is turned on.
Claim 26
Dependent Claim
32 words
The improvement of a system for detecting an impending kickback condition in a power tool as recited in claim 18 wherein said filtering means computes an average value of the sampled values.
Claim 27
Dependent Claim
147 words
In a power tool of the type having an implement driven by an electric motor, said electric motor being supplied with current from an AC source, the improvement of an anti-kickback control system for said power tool comprising: (a) sampling means for sampling successive periods of the current through said motor at determinate points in the current waveform; (b) filtering means for filtering the sampled values from said sampling means; (c) means connected to said filtering means for storing the results of filtering successive sampled values of motor current and for computing the difference between the stored results as a measure of the rate of change of said results of filtering; (d) comparing means for comparing said measure of the rate of change with a threshold; and (e) means for inhibiting the supply of current to said motor if the measured rate of change exceeds said threshold.
Claim 28
Dependent Claim
147 words
In a power tool of the type having an implement driven by an electric motor, said electric motor being supplied with current from an AC source, the improvement of an anti-kickback control system for said power tool comprising: (a) sampling means for sampling successive periods of the current through said motor at determinate points in the current waveform; (b) filtering means for filtering the sampled values from said sampling means; (c) means connected to said filtering means for storing the results of filtering successive sampled values of motor current and for computing the difference between the stored results as a measure of the rate of change of said results of filtering; (d) comparing means for comparing said measure of the rate of change with a threshold; and (e) means for inhibiting the supply of current to said motor if the measured rate of change exceeds said threshold.
Claim 29
Dependent Claim
37 words
The anti-kickback control system as recited in claim 22 wherein said means for sampling takes a plurality of current samples in the vicinity of the peak current value during at least each cycle of said AC source.
Claim 30
Dependent Claim
66 words
The anti-kickback control system as recited in claim 22 wherein said electric motor is supplied with current from said AC source through an electronic switching circuit which is turned on each half cycle of said AC source, said sampling means including timing means to control the taking of a plurality of current samples at a time measured from when said electronic switching circuit is turned on.
Claim 31
Dependent Claim
21 words
The anti-kickback control system as recited in claim 22 wherien said filtering means computes an average value of the sampled values.
Claim 32
Dependent Claim
177 words
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 supplied with current through an electronic switching circuit, the improvement of an anti-kickback control system for said power tool comprising: (a) sampling means for sampling successive periods of the current through said motor at determinate points in the current waveform generated by said electronic switching circuit; (b) filtering means for filtering the sampled values from said sampling means; (c) means connected to said filtering means for storing the results of filtering successive sampled values of motor current and for computing the difference between the stored results as a measure of the rate of change of said results of filtering; (d) comparing means for comparing said measure of the rate of change with a threshold; and (e) means for controlling said electronic switching circuit to block the supply of current to said electric motor if the measured rate of change exceeds said threshold.
Claim 33
Dependent Claim
177 words
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 supplied with current through an electronic switching circuit, the improvement of an anti-kickback control system for said power tool comprising: (a) sampling means for sampling successive periods of the current through said motor at determinate points in the current waveform generated by said electronic switching circuit; (b) filtering means for filtering the sampled values from said sampling means; (c) means connected to said filtering means for storing the results of filtering successive sampled values of motor current and for computing the difference between the stored results as a measure of the rate of change of said results of filtering; (d) comparing means for comparing said measure of the rate of change with a threshold; and (e) means for controlling said electronic switching circuit to block the supply of current to said electric motor if the measured rate of change exceeds said threshold.
Claim 34
Dependent Claim
47 words
The anti-kickback control system as recited in claim 26 wherein said electronic switching circuit is periodically turned on, said sampling means including timing means to control the taking of a plurality of current samples at a time measured from when said electronic switching circuit is turned on.
Claim 35
Dependent Claim
38 words
The anti-kickback control system as recited in claim 26 wherein said sampling means takes a plurality of current samples in the vicinity of the peak current value during the periods when said electronic switching circuit is turned on.
Claim 36
Dependent Claim
21 words
The anti-kickback control system as recited in claim 26 wherein said filtering means computes an average value of the sampled values.
Claim 37
Dependent Claim
203 words
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 supplied with current through an electronic switching circuit, the improvement of an anti-kickback control system for said power tool comprising: (a) a switch which when closed generates a signal to said electronic switching circuit to cause said electronic switching circuit to periodically supply current to said electric motor; (b) sampling means for sampling successive periods of the current through said motor at determinate points in the current waveform generated by said electronic switching circuit; (c) filtering means for filtering the sampled values from said sampling means; (d) means connected to said filtering means for storing the results of filtering successive sampled values of motor current and for computing the difference between the stored results as a measure of the rate of change of said results of filtering; (e) comparing means for comparing the measured rate of change with a threshold; and (f) means for controlling said electronic switching circuit to block the supply of current to said electric motor if the measured rate of change exceeds said threshold.
Claim 38
Dependent Claim
203 words
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 supplied with current through an electronic switching circuit, the improvement of an anti-kickback control system for said power tool comprising: (a) a switch which when closed generates a signal to said electronic switching circuit to cause said electronic switching circuit to periodically supply current to said electric motor; (b) sampling means for sampling successive periods of the current through said motor at determinate points in the current waveform generated by said electronic switching circuit; (c) filtering means for filtering the sampled values from said sampling means; (d) means connected to said filtering means for storing the results of filtering successive sampled values of motor current and for computing the difference between the stored results as a measure of the rate of change of said results of filtering; (e) comparing means for comparing the measured rate of change with a threshold; and (f) means for controlling said electronic switching circuit to block the supply of current to said electric motor if the measured rate of change exceeds said threshold.
Claim 39
Dependent Claim
44 words
The anti-kickback control system as recited in claim 30 wherein after the supply of current to said electric motor has been blocked, said switch when opened and closed again generates a signal to said electronic switching circuit to supply current to said electric motor.
Claim 40
Dependent Claim
121 words
In a power tool of the type having an implement driven by an electric motor, the improvement of an anti-kickback control system for said power tool comprising: (a) monitoring means for monitoring a signal proportional to the current supplied to said electric motor; (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 coupling of power to said implement from said electric motor.
Claim 41
Dependent Claim
121 words
In a power tool of the type having an implement driven by an electric motor, the improvement of an anti-kickback control system for said power tool comprising: (a) monitoring means for monitoring a signal proportional to the current supplied to said electric motor; (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 coupling of power to said implement from said electric motor.
Claim 42
Dependent Claim
89 words
The antikickback control system recited in claim 32 wherein said electric motor is adapted to be connected to a source of electrical power through a switching device, said monitoring means includes a current-to-voltage converter providing a voltage signal proportional to the current to said electric motor and an analog-to-digital converter for converting said voltage signal to a digital signal supplied to said microprocessor, and said control means controls said switching device to block the connection of electrical power to said electric motor in response to said inhibit output signal.
Claim 43
Dependent Claim
48 words
The anti-kickback control system recited in claim 32 wherein said monitoring means takes successive samples of said signal proportional to current at determinate points in the signals waveform, said microprocessor further being programmed to filter the plurality of sampled values to obtain an accurate measure of motor current.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-02-03 | 1984-08-04 | 1985-02-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-02-03 | 1988-08-04 | 1989-02-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-02-03 | 1992-08-04 | 1993-02-03 | $7700.00 | Window Closed / Lapsed |