Patent US3673482A successfully refreshed from Google Patents.
US3673482A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatically operating and controlling reciprocating motion
Assignee: Herbert Morris Ltd
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Filing: 1971-03-05
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Granted: 1972-06-27
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Expires: 1991-03-05
Abstract
Abstract A linear induction motor for automatically operating a reciprocating member or door incorporating a control system for the motor by which the door is accelerated at full thrust to travelling speed, means for reducing the motor thrust to enable the door to coast at approximately constant speed until reaching a limit switch which initiates reverse thrust braking, with means to automatically cut out the braking as soon as the door has stopped and means for driving the door at low thrust to a final limit switch, an overspeed relay for initiating the reversal of the motor thrust when the door speed exceeds a predetermined value.
Inventors
- 👤 Anthony Walter Davey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 20:32
CPC Classifications
G; G05; G05D; G05D3/00; G05B; G05B2219/00; G05B2219/30; G05B2219/41; G05B2219/41327; G05B2219/43; G05B2219/43076; G05B2219/43077; G05B2219/45; G05B2219/45242; G05B2219/49; G05B2219/49382
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
111 words
A linear induction motor for automatically operating a reciprocating door the invention comprising a control system for the motor by which the door is accelerated at full thrust to travelling speed, means for reducing the motor thrust to enable the door to coast at approximately constant speed, a limit switch to initiate reverse thrust braking, means to automatically cut out the braking as soon as the door has stopped, means for driving the door at low thrust, a final limit switch for limiting the movement of the door at low thrust and an overspeed relay for initiating the reversal of the motor thrust when the door speed exceeds a predetermined value.
Claim 2
Dependent Claim
111 words
A linear induction motor for automatically operating a reciprocating door the invention comprising a control system for the motor by which the door is accelerated at full thrust to travelling speed, means for reducing the motor thrust to enable the door to coast at approximately constant speed, a limit switch to initiate reverse thrust braking, means to automatically cut out the braking as soon as the door has stopped, means for driving the door at low thrust, a final limit switch for limiting the movement of the door at low thrust and an overspeed relay for initiating the reversal of the motor thrust when the door speed exceeds a predetermined value.
Claim 3
Dependent Claim
45 words
A linear induction motor as in claim 1 in which the control for the motor comprises an electronic detector circuit divided into a power supply circuit, a reverse braking circuit, a door minimum speed circuit, an over speed circuit and a fail to safety circuit.
Claim 4
Dependent Claim
34 words
A linear induction motor as in claim 1 and including a tachometer generator which if the door speed exceeds a predetermined value initiates a reversal of the motor contacts to apply reverse thrust braking.
Claim 5
Dependent Claim
39 words
A linear induction motor as in claim 1 including a door edge safety switch, and a relay energized thereby to initiate the opening of the motor contactor and tHe reversing of the tachometer generator to apply reverse thrust braking.
Claim 6
Dependent Claim
37 words
A linear induction motor as in claim 1 incorporating a safety circuit to prevent the motor from damage if the door is stalled by an obstruction or in the event of a failure of the tachometer generator.
Claim 7
Dependent Claim
54 words
A linear induction motor as in claim 1 incorporating a tachometer generator, a circuit switch, a relay energized by the switch to initiate the reversal of the motor and tachometer generator contacts to apply reverse motor thrust for braking purposes and speed causing means for determining the instant for cutting off the decellerating power.
References Cited (Backward Citations)
US3039764A
Cited
US3462883A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-27 | 1975-12-27 | 1976-06-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-27 | 1979-12-27 | 1980-06-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-27 | 1983-12-27 | 1984-06-27 | $7700.00 | Window Closed / Lapsed |