US3562618A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Torque control circuit for electric motors
Assignee: RAM TOOL CORP
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Filing: 1967-11-03
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Granted: 1971-02-09
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Expires: 1987-11-03
Abstract
Abstract A torque control circuit wherein a silicon controlled rectifier is connected in series with the field and armature of an electric motor and is gated by a pickup winding which is magnetically coupled to the field of the motor such that the motor speed depends upon motor load current.
Inventors
- 👤 Athanase N Tsergas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 13:56
CPC Classifications
H; H02; H02K; H02K23/00; H02K23/66; B; B25; B25B; B25B23/00; B25B23/14; B25B23/147; H02P; H02P25/00; H02P25/02; H02P25/10; H02P25/14
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
162 words
A circuit for controlling the torque of an electric motor of a hand-operated power tool having a series field winding comprising; a pickup winding mounted on the stator core and magnetically coupled to the field winding and producing a pair of bias output signals of opposite polarity and proportional to the field current; a gated device connected in series with the series combination of armature and field winding and one of the motor terminals; the gated device comprising a pair of silicon controlled rectifiers with the anode of one connected to the cathode of the other, and the cathode of the one connected to the anode of the other, one of said bias output signals connected to the gate of the first silicon controlled rectifier, and the other bias output signal connected to the gate of the second silicon controlled rectifier, so that the first and second silicon controlled rectifiers are gated to conduct current proportional to the load on the motor.
Claim 2
Dependent Claim
162 words
A circuit for controlling the torque of an electric motor of a hand-operated power tool having a series field winding comprising; a pickup winding mounted on the stator core and magnetically coupled to the field winding and producing a pair of bias output signals of opposite polarity and proportional to the field current; a gated device connected in series with the series combination of armature and field winding and one of the motor terminals; the gated device comprising a pair of silicon controlled rectifiers with the anode of one connected to the cathode of the other, and the cathode of the one connected to the anode of the other, one of said bias output signals connected to the gate of the first silicon controlled rectifier, and the other bias output signal connected to the gate of the second silicon controlled rectifier, so that the first and second silicon controlled rectifiers are gated to conduct current proportional to the load on the motor.
Claim 3
Dependent Claim
12 words
The circuit of claim 1 wherein said gated device comprises a triac.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-02-08 | 1974-08-10 | 1975-02-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-08 | 1978-08-10 | 1979-02-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-08 | 1982-08-10 | 1983-02-09 | $7700.00 | Window Closed / Lapsed |