US3628115A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Variable-speed hoist control
Assignee: Uni-Light Hoist and Reel Inc
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Filing: 1969-06-02
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Granted: 1971-12-14
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Expires: 1989-06-02
Abstract
Abstract A hoist of light weight and high capacity with infinitely variable speed and holding characteristics. A sprocket engaged with a roller chain is driven through a multiple-stage spur gear reduction train by a high-speed universal reversible electric motor energized through a modified silicon control rectifier. The reduction gears are of high-tensile alloy steel, mounted on roller bearings to give an efficient drive, and the gear reduction is of such high ratio as to make the gear train irreversible under the rated load of the hoist, so that the SCR control of the high-speed motor gives positive variable-speed lifting, lowering, and holding control of the rated load. The motor control circuit includes a leakage resistor connected across the conducting electrodes of the SCR to inhibit any reversal of the motor.
Inventors
- 👤 Dana L Pruitt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 09:46
CPC Classifications
B; B66; B66D; B66D3/00; B66D3/18; B66D3/20; B66D3/22; B66C; B66C13/00; B66C13/18; B66C13/22; B66C13/23; B66C13/24; B66D2700/00; B66D2700/02; B66D2700/026
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
94 words
A variable speed control means for an electric motor, comprising a silicon controlled rectifier having principal conducting electrodes and a gate electrode, circuit means for connecting the principal conducting electrodes to control the current supplied to the electric motor, means to vary the voltage supply into the gate electrode to thereby control the current supplied through the principal electrodes to the motor, and a leakage resistor connected across the principal conducting electrodes of the silicon controlled rectifier to maintain a lowvoltage supply of full wave AC to the motor for regeneratively braking the motor.
Claim 2
Dependent Claim
94 words
A variable speed control means for an electric motor, comprising a silicon controlled rectifier having principal conducting electrodes and a gate electrode, circuit means for connecting the principal conducting electrodes to control the current supplied to the electric motor, means to vary the voltage supply into the gate electrode to thereby control the current supplied through the principal electrodes to the motor, and a leakage resistor connected across the principal conducting electrodes of the silicon controlled rectifier to maintain a lowvoltage supply of full wave AC to the motor for regeneratively braking the motor.
Claim 3
Dependent Claim
34 words
A variable speed control means according to claim 1 wherein said leakage resistor is adapted to pass sufficient current to maintain a magnetic field in the motor but insufficient current to drive the motor.
Claim 4
Dependent Claim
165 words
A variable speed control means for an AC powered series electric motor, comprising a silicon controlled rectifier having principal conducting electrodes and a gate electrode, a pair of input conductors for connection to an AC supply circuit, a pair of output conductors for connection to the electric motor, means connecting the input connectors to the output connectors and including said conducting electrodes being one input conductor and an output conductor, variable voltage dividing means connected across the input conductors for deriving a control voltage in each voltage cycle of the AC supply circuit and means to apply such control voltage to said gate electrode to cause the conducting electrodes to conduct during a variable portion of said cycle and thereby to supply power from the input conductors through the principal electrodes to the output conductors for operating the motor, and a leakage resistor connected across said principal conducting electrodes to maintain a low-voltage supply of full-wave AC to the motor for regeneratively braking the motor.
Claim 5
Dependent Claim
165 words
A variable speed control means for an AC powered series electric motor, comprising a silicon controlled rectifier having principal conducting electrodes and a gate electrode, a pair of input conductors for connection to an AC supply circuit, a pair of output conductors for connection to the electric motor, means connecting the input connectors to the output connectors and including said conducting electrodes being one input conductor and an output conductor, variable voltage dividing means connected across the input conductors for deriving a control voltage in each voltage cycle of the AC supply circuit and means to apply such control voltage to said gate electrode to cause the conducting electrodes to conduct during a variable portion of said cycle and thereby to supply power from the input conductors through the principal electrodes to the output conductors for operating the motor, and a leakage resistor connected across said principal conducting electrodes to maintain a low-voltage supply of full-wave AC to the motor for regeneratively braking the motor.
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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) | 1974-12-13 | 1975-06-14 | 1975-12-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-12-13 | 1979-06-14 | 1979-12-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-12-13 | 1983-06-14 | 1983-12-14 | $7700.00 | Window Closed / Lapsed |