Automatic Door Operator
The automatic door operator is mounted on the roof of the elevator car. In addition to driving the opening and closing of the car door, it must also actuate a mechanical linkage mechanism to ensure the landing door opens and closes synchronously with the car door. To ensure that the elevator doors open and close rapidly and smoothly, the automatic door operator system requires precise speed regulation. When utilizing a small DC servo motor, a method involving series and parallel resistor connections can be employed. When utilizing a small AC torque motor, a common speed regulation method involves the addition of an eddy current brake. Speed regulation for DC motors is relatively simple, and they generate less heat during low-speed operation; conversely, AC door operators generate significant heat at low speeds, placing higher demands on the three-phase motor's locked-rotor performance and insulation integrity.
Command Buttons
In-Car Command and Landing Call Controls
The in-car operating panel features an illuminated button corresponding to each floor level.
Within the elevator control system, these are referred to as "command buttons." After entering the car, a passenger presses the button corresponding to their desired destination floor; the button's indicator light then illuminates, signifying that the in-car command has been registered. Upon reaching the destination floor, the command is cleared, and the button's light extinguishes. Elevator landing call signals are initiated via buttons located adjacent to the doorways on each floor. In elevators utilizing signal control or collective control systems, every intermediate floor is equipped with both "Up" and "Down" call buttons; the top floor, however, features only a "Down" call button, while the bottom floor features only an "Up" call button.
Floor Selection and Directioning
Several common methods are employed for floor selection and directioning, including: manual handle switch directioning; shaft-mounted layered selector switch directioning; logic circuits utilizing shaft-mounted permanent magnet switches and relays; mechanical floor selectors; systems utilizing bistable magnetic switches and electronic digital circuits; and electronic pulse-based floor selection devices.
Elevator Directioning and Floor Selection Circuitry: The elevator's direction control system functions by comparing the destination commands issued by passengers inside the car-along with the landing call signals from various floors-against the elevator's current physical location. Any in-car commands or landing call signals situated *above* the elevator's current position signal the elevator to proceed *upward*; conversely, signals situated *below* the current position signal it to proceed *downward*.
The direction control logic must adhere to the following key principles:
In-car destination commands take precedence over landing call signals when determining the elevator's direction of travel. The elevator must prioritize responding to passenger call signals from the furthest floors. When the elevator is under manual operation by an attendant-and provided the car has not yet begun to move-the attendant must be able to manually override and alter the elevator's direction of travel. During maintenance mode, directional control is exercised directly by maintenance personnel; the elevator will only move while the technician continuously presses (specifically via "inching" control) the directional buttons located either on the in-car control panel or atop the car roof; upon releasing the directional button, the elevator immediately comes to a halt.
Floor Display Circuitry: Passenger elevator cars are invariably equipped with an in-car floor display; however, the provision of floor displays at the individual landings is left to the discretion of the elevator manufacturer, depending on the specific project requirements. Historically, elevators featured a floor display at every landing; however, with advancements in elevator speeds and the sophistication of group control dispatch systems, many modern installations have eliminated landing-based floor displays-or retain them only at the designated base station-opting instead for combined audio-visual notification panels to signal an elevator's arrival at a specific call station. For instance, as the elevator approaches a landing, an arrival chime sounds, and directional indicator lights flash or illuminate to clearly indicate the elevator's direction of travel; some systems further incorporate in-car voice announcements to provide audible cues to passengers.
