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US 4,278,150 AGranted
Elevator system
AssigneeWestinghouse Electric Corp.
InventorsHenry A. Wehrli, III, Dirk J. Boomgaard, Alvin O. Lund, deceased
Life of this patent
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Abstract
A traction elevator system including an elevator car driven by a drive arrangement having electrically isolated high and low speed components. Fixed AC and controllable DC voltages are selectively applied to the high and low speed components, respectively, at predetermined portions of the run, to control the drive torque to provide smooth operation of the elevator car.
Claims35
An elevator drive system for selectively providing motoring and system braking torques which control the starting, driving, and stopping of an elevator car during a run, comprising:
- an elevator car,
- alternating current motor means disposed to effect movement of said elevator car,
- said alternating current motor means including electrically isolated high and low speed components,
- first control means for applying a non-adjustable alternating current line voltage to said high speed component, to develop a motoring torque,
- second control means for applying a controllable direct current voltage to said low speed component, with said controllable direct current voltage being capable of developing a braking torque in the low speed component which provides a system braking torque sufficient to stop said elevator car when moving, and to prevent said elevator car from moving when stationary, notwithstanding the simultaneous application of the alternating current line voltage to said high speed component,
- and third control means for controlling said first and second control means such that the high and low speed components simultaneously develop motoring and braking torques during at least a selected portion of a run, with the system braking torque exceeding the motoring torque at least once during said selected portion of a run.
3 more elements
An elevator system comprising:
- an elevator car,
- drive means for said elevator car including first means for providing a motoring torque and second means for providing a braking torque,
- speed pattern means providing a single speed pattern signal when the elevator car reaches a predetermined distance from the desired stopping point, with said speed pattern signal being indicative of the desired deceleration of the elevator car, and with the initial magnitude of the speed pattern signal corresponding to a car speed which exceeds the maximum possible speed of the elevator car,
- tachometer means providing an actual speed signal,
- comparator means providing a difference signal responsive to the difference between said speed pattern signal and said actual speed signal,
- and anticipation means which provides an anticipation signal responsive to the speed pattern and actual speed signals with said second means initiating a braking torque which opposes the motoring torque provided by the first means, in response to said anticipation signal.
3 more elements
An elevator system, comprising:
- an elevator car,
- drive means for said elevator car,
- pattern generator means providing a deceleration pattern signal indicative of the desired speed of the elevator car,
- tachometer means providing a tach signal responsive to the actual speed of the elevator car,
- comparator means providing a difference signal responsive to the difference between said pattern signal and said tach signal,
- and control means providing a signal for said drive means in response to said difference signal,
- said pattern generator means including a read-only memory having a speed pattern stored therein, and addressing means for addressing the read-only memory in response to movement of the elevator car when the elevator car reaches a predetermined first distance from the desired stopping point, with the car movement increment which changes the address applied to the read-only memory being relatively large until the elevator car reaches a predetermined second distance from the desired stopping point, at which point the car movement increment which changes the address applied to the read-only memory is substantially reduced.
4 more elements
An elevator system, comprising:
- an elevator car,
- drive means for said elevator car,
- pattern generator means, said pattern generator means providing a speed pattern signal indicative of the desired speed of the elevator car, during at least a portion of a run,
- means providing a first train of pulses responsive to the movement of said elevator car, with the width of the pulses in the first train varying in response to the speed of the elevator car,
- means providing a second train of pulses in response to the first train of pulses, with said pulses in the second train having a constant width,
- means integrating said second train of pulses to provide a unidirectional signal responsive to car speed having a ripple component whose frequency is responsive to the pulse rate of the second train of pulses,
- timing means providing timing signals responsive to said first train of pulses,
- sample and hold means responsive to said timing means and to said unidirectional signal, said sample and hold means sampling and holding each cycle of the ripple frequency at a time determined by said timing means, to provide a substantially ripple-free actual speed signal,
- comparator means providing a difference signal responsive to the difference between said speed pattern signal and said actual speed signal,
- and control means responsive to said difference signal for controlling said drive means.
7 more elements
Dependencies are inferred from the claim text.