Elevator – industrial lift truck – or stationary lift for vehicle – Stationary lift for roadway vehicle or required component... – Having specific drive means for support
Patent
1976-04-14
1978-06-13
Schaefer, Robert K.
Elevator, industrial lift truck, or stationary lift for vehicle
Stationary lift for roadway vehicle or required component...
Having specific drive means for support
B66B 140
Patent
active
040943852
ABSTRACT:
In an a-c elevator, an elevator car suspended by ropes is driven by an induction motor for vertical movement. A system commonly used for controlling the device including thyristors connected in parallel with opposite polarities across a three-phase a-c power source and the induction motor for controlling the motoring torque produced by the induction motor, a bridge rectifier including a thyristor for supplying direct current to the induction motor for controlling the braking torque produced by the induction motor, and means for controlling the operating phase of the thyristors in the thyristor device and the thyristor in the bridge rectifier depending on the error between the instructed speed and the actual speed of the elevator car. When the elevator car stops at a target floor and passengers get on and off the elevator car, the variation in the load of the elevator car results in an increase or decrease in the length of the ropes thereby giving rise to an error between the floor level of the target floor and that of the elevator car. A levelling apparatus is provided which comprises a position detector detecting this level error in either direction, and a level correction speed pattern signal generator generating a level correction speed pattern signal in response to the appearance of an output from the position detector, so that the operating phase of the thyristors in the thyristor device and the thyristor in the bridge rectifier can be controlled depending on the error between the level correction speed pattern and the actual speed of the elevator car.
REFERENCES:
patent: 2847091 (1958-08-01), Santini et al.
patent: 3687235 (1972-08-01), Mitsui et al.
patent: 3749203 (1973-07-01), Hoelscher
patent: 3798519 (1974-03-01), Habisohn
patent: 3815711 (1974-06-01), Hoelscher
Kameyama Tadao
Komuro Katsu
Maeda Yasuyuki
Mitsui Nobuo
Duncanson Jr. W. E.
Hitachi , Ltd.
Schaefer Robert K.
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