Patent US4355704A successfully refreshed from Google Patents.
US4355704A
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Procedure for fine positioning an alternating current lift
Assignee: Elevator GmbH
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Filing: 1980-08-26
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Granted: 1982-10-26
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Expires: 2000-08-26
Abstract
Abstract Procedure for exact aligning with the storey floor level of a lift cage driven by an alternating current motor, wherein the current in one or several phases of the lift's drive motor (2) is choked with a controllable choke element (22). The control is governed by a control unit (23) which receives information of the lift cage's (8) true velocity, constituting a feedback-connected control loop which imparts to the lift cage in fine adjustment running a low velocity from which the lift cage is able to stop at the storey floor level within a required tolerance range.
Inventors
- 👤 Heimo Makinen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 08:22
CPC Classifications
B; B66; B66B; B66B1/00; B66B1/24; B66B1/28; B66B1/30; B66B1/308; B66B1/34; B66B1/36; B66B1/40
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
145 words
An improved method for exact alignment of an elevator car with the floor level of a building, said elevator being driven by an alternating current drive motor connected to a speed control, the current in one or several phases of the elevator drive motor being choked with a controllable choke element, wherein the improvement comprises the steps of: governing elevator car control by a control unit receiving elevator car true velocity from a feedback control loop imparting fine adjustment to the elevator car running at a slow speed, stopping at a selected floor level within a required tolerance range; operating speed control of the drive motor only in a range in which counter-torque of said motor is positive, and when motor counter-torque is negative, controlling the velocity of the elevator car with the aid of a velocity measuring unit acting upon an elevator car brake.
Claim 2
Dependent Claim
145 words
An improved method for exact alignment of an elevator car with the floor level of a building, said elevator being driven by an alternating current drive motor connected to a speed control, the current in one or several phases of the elevator drive motor being choked with a controllable choke element, wherein the improvement comprises the steps of: governing elevator car control by a control unit receiving elevator car true velocity from a feedback control loop imparting fine adjustment to the elevator car running at a slow speed, stopping at a selected floor level within a required tolerance range; operating speed control of the drive motor only in a range in which counter-torque of said motor is positive, and when motor counter-torque is negative, controlling the velocity of the elevator car with the aid of a velocity measuring unit acting upon an elevator car brake.
References Cited (Backward Citations)
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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) | 1985-10-25 | 1986-04-26 | 1986-10-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-10-25 | 1990-04-26 | 1990-10-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-10-25 | 1994-04-26 | 1994-10-26 | $7700.00 | Window Closed / Lapsed |