Managing an encoder malfunction in an elevator drive system
AssigneeOtis Elevator Company
InventorsEdward D. Piedra, Jeffrey M. Izard, Ismail Agirman
Life of this patent
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Abstract
An encoder failure in an elevator drive system is detected and managed. A velocity of the elevator drive system is provided by an encoder signal (60) and compared with a minimum velocity threshold (62). An encoder fault timer is incremented when the velocity is less than the minimum velocity threshold (64). The elevator drive system is disabled when the encoder fault timer reaches a fault threshold time (66).
Claims23
A method for detecting and managing an encoder failure in an elevator drive system, the method comprising:
- providing an encoder signal related to a velocity of the elevator drive system;
- comparing the sensed velocity with a minimum velocity threshold;
- incrementing an encoder fault timer when the sensed velocity is less than the minimum velocity threshold;
- and
- disabling the elevator drive system substantially immediately after the encoder fault timer reaches a fault threshold time.
A method for controlling an elevator drive system, the method comprising:
- monitoring a velocity of the elevator drive system;
- disabling a drive inverter in the elevator drive system substantially immediately after the velocity remains below a velocity threshold for a fault threshold time;
- and
- engaging a sheave brake to prevent motion of a drive sheave in the elevator drive system.
A system comprising:
- an elevator hoist machine including a motor, a rotating member driven by the motor for actuating a rope that connects an elevator car and a counterweight, and a brake for preventing the rotating member from rotating;
- an encoder operatively connected to the motor for providing a signal related to a position and velocity of the motor;
- and
- a drive controller for receiving the signal from the encoder and disabling the motor and engaging the brake substantially immediately after the velocity of the motor remains below a velocity threshold for a fault threshold time.
A system comprising:
- an elevator hoist machine including a motor, a rotating member driven by the motor for actuating a rope that connects an elevator car and a counterweight, and a brake for preventing the rotating member from rotating;
- an encoder operatively connected to the motor for providing a signal related to a position and velocity of the motor;
- and
- a drive controller for receiving the signal from the encoder, controlling the motor as a function of a commanded speed and the signal from the encoder, and disabling the motor and engaging the brake after the velocity of the motor indicated by the signal from the encoder remains below a velocity threshold for a fault threshold time while the commanded speed is greater than zero.
Dependencies are inferred from the claim text.