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US 4,094,385 AGranted
Levelling apparatus for AC elevator
AssigneeHitachi, Ltd.
InventorsYasuyuki Maeda, Nobuo Mitsui, Tadao Kameyama, Katsu Komuro
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AssigneeHitachi, Ltd.
InventorsYasuyuki Maeda, Nobuo Mitsui, Tadao Kameyama, Katsu Komuro
Estimating the term…
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.
A levelling apparatus for an AC elevator system comprising a three-phase induction motor, motoring torque control means for controlling the motoring torque produced by said motor, braking torque control means for controlling the braking torque produced by said motor until a speed of said motor reaches a very low speed in the vicinity of zero, and an elevator car driven for vertical movement by said motor through a rope, wherein the improvement comprises level error detecting means for detecting dislocation of a floor level of said elevator car in either direction from the floor level of a target floor and means for controlling the torque produced by said motor by actuating said motoring torque control means and said braking torque control means in response to an output of said level error detecting means.
A levelling apparatus for an AC elevator system comprising a three-phase induction motor, motoring torque control means for controlling the motoring torque produced by said motor, braking torque control means for controlling the braking torque produced by said motor until the speed of said motor reaches a very low speed in the vicinity of zero, an elevator car driven for vertical movement by said motor through a rope, means for generating a normal running speed pattern signal for causing normal service travelling movement of said elevator car, means for generating a speed signal representing the travelling speed of said elevator car, and means for actuating said motoring torque control means and said braking torque cntrol means in response to the error between the output of said normal running speed pattern signal generating means and the output of said travelling speed signal generating means thereby controlling the travelling speed of said elevator car, wherein the improvement comprises level error detecting means for detecting dislocation of the floor level of said elevator car in either direction from the floor level of a target floor, means for generating a level correction speed pattern signal in response to the appearance of an output from said level error detecting means, and means for changing said level correction speed pattern signal over to said travelling speed control means in lieu of said normal running speed pattern signal.
Dependencies are inferred from the claim text.