US4307325A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital control system for electric motors in power tools and the like
Assignee: Black and Decker Inc
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Filing: 1980-03-24
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Granted: 1981-12-22
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Expires: 2000-03-24
Abstract
Abstract A digital control system for electric motors in power tools of the portable or stationary type includes a microcomputer controlled speed regulator connected to the electric motor for maintaining a preselected speed of the motor substantially constant between no load and full load operation of the motor. The preselected speed is inputted to the microcomputer by means of a rotary switch or similar input switching arrangement. When the tool is just starting or the operator changes the speed switch, the microcomputer controls the speed of the motor to slowly approach the desired speed. The microcomputer is programmed to detect an overload condition and activate an alarm, and an impending kickback condition and stop the electric motor.
Inventors
- 👤 David A. Saar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 13:01
CPC Classifications
B; B23; B23B; B23B45/00; B23B45/02; H; H02; H02H; H02H6/00; H02H6/005; H02H7/00; H02H7/08; H02H7/085; H02H7/0854; H02P; H02P23/00; H02P23/0077; H02P25/00; H02P25/02; H02P25/10; H02P25/14; H02P25/145; B23B2260/00; B23B2260/128; Y; Y10; Y10S; Y10S388/00; Y10S388/907; Y10S388/923; Y10S388/934; Y10S388/935; Y10S388/937
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
102 words
The method of monitoring the operating temperature of a motor including the steps of: storing a matrix of heating values representing the relative heating condition of the motor when operated at various speeds and loading conditions with one heating value being assigned to each designated operating region of the motor, periodically determining in which of the designated operating regions the motor is currently operating based upon the speed of the motor and the voltage applied to the motor and adding the corresponding heating value assigned to that region to an accumulated total, and determining whenever the accumulated total exceeds a predetermined amount.
Claim 2
Independent Claim
102 words
The method of monitoring the operating temperature of a motor including the steps of: storing a matrix of heating values representing the relative heating condition of the motor when operated at various speeds and loading conditions with one heating value being assigned to each designated operating region of the motor, periodically determining in which of the designated operating regions the motor is currently operating based upon the speed of the motor and the voltage applied to the motor and adding the corresponding heating value assigned to that region to an accumulated total, and determining whenever the accumulated total exceeds a predetermined amount.
Claim 3
Dependent Claim
127 words
A control circuit for monitoring the operating temperature of an electric motor, comprising: a speed sensor for sensing the speed of the motor and producing a corresponding speed signal, first digital storage means for storing a plurality of heating values representing the relative steady-state heat generating condition of the motor when operated at various speeds and loading conditions, second digital storage means for storing an accumulated total of past heating values, and means for periodically selecting from said first digital storage means the appropriate heating value corresponding to the present operating condition of the motor as determined in accordance with said speed signal and the voltage being applied to the motor and adding said appropriate heating value to the accumlated total in said second digital storage means.
Claim 4
Dependent Claim
127 words
A control circuit for monitoring the operating temperature of an electric motor, comprising: a speed sensor for sensing the speed of the motor and producing a corresponding speed signal, first digital storage means for storing a plurality of heating values representing the relative steady-state heat generating condition of the motor when operated at various speeds and loading conditions, second digital storage means for storing an accumulated total of past heating values, and means for periodically selecting from said first digital storage means the appropriate heating value corresponding to the present operating condition of the motor as determined in accordance with said speed signal and the voltage being applied to the motor and adding said appropriate heating value to the accumlated total in said second digital storage means.
Claim 5
Dependent Claim
25 words
The control circuit of claim 2 further including means for determining whenever the accumulated total in said second digital storage means exceeds a predetermined amount.
Claim 6
Dependent Claim
13 words
The control circuit of claim 2 wherein said heating values are empirically derived.
Claim 7
Dependent Claim
174 words
In a power tool having an electric motor and means for applying power to the motor, a control circuit for monitoring the operating temperature of the motor comprising: a speed sensor for sensing the speed of the motor and producing a corresponding speed signal; and microcomputer means for monitoring the temperature of the motor in accordance with information derived from said speed signal and the power applied to the motor including first memory means for storing a plurality of heating values representing the relative steady-state heat generating condition of the motor when operated in a corresponding plurality of designated regions each defined by a predetermined range of speed and torque values, storage means for storing an accumulated total of past heating values, and processor means for periodically determining from said speed signal and the power applied to the motor the designated region within which the motor is operating, selecting in accordance therewith the corresponding heating value stored in said first memory means, and adding said heating value to the contents of said storage means.
Claim 8
Dependent Claim
174 words
In a power tool having an electric motor and means for applying power to the motor, a control circuit for monitoring the operating temperature of the motor comprising: a speed sensor for sensing the speed of the motor and producing a corresponding speed signal; and microcomputer means for monitoring the temperature of the motor in accordance with information derived from said speed signal and the power applied to the motor including first memory means for storing a plurality of heating values representing the relative steady-state heat generating condition of the motor when operated in a corresponding plurality of designated regions each defined by a predetermined range of speed and torque values, storage means for storing an accumulated total of past heating values, and processor means for periodically determining from said speed signal and the power applied to the motor the designated region within which the motor is operating, selecting in accordance therewith the corresponding heating value stored in said first memory means, and adding said heating value to the contents of said storage means.
Claim 9
Dependent Claim
37 words
The control circuit of claim 5 wherein said processor means is programmed to determined the level of power applied to the motor in accordance with the firing angle of a semiconductor control device connected to the motor.
Claim 10
Independent Claim
94 words
A method of monitoring the temperature of a motor including the steps of: determining the cooling effect of the motor in terms of its speed, determining the heating effect of the motor in terms of applied power, determining a heating value, which is a function of both the determined cooling effect and the determined heating effect, from a set of heating values established over a predetermined motor operating range, adding the heating value periodically to an accumulated total of past heating values, and signalling the occurrence of the accumulated total exceeding a predetermined amount.
Claim 11
Independent Claim
94 words
A method of monitoring the temperature of a motor including the steps of: determining the cooling effect of the motor in terms of its speed, determining the heating effect of the motor in terms of applied power, determining a heating value, which is a function of both the determined cooling effect and the determined heating effect, from a set of heating values established over a predetermined motor operating range, adding the heating value periodically to an accumulated total of past heating values, and signalling the occurrence of the accumulated total exceeding a predetermined amount.
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) | 1984-12-21 | 1985-06-22 | 1985-12-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-12-21 | 1989-06-22 | 1989-12-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-12-21 | 1993-06-22 | 1993-12-22 | $7700.00 | Window Closed / Lapsed |