1. Spring-type automatic door closing: opening the door requires a larger torsion force to pull the door, that is, when opening the door, the tension spring needs to be stretched, and the door is operated until the door opening limit switch signal is input (door opening is completed), and the outer door has been pulled back by the maximum tension spring. As a result, the torque of the elevator door motor is the maximum. At this time, the elevator door machine motor must be switched to a torque function that does not move, and stops at the door opening to complete the function. The door closing is affected by the pull back of the tension spring. At this time, the door machine motor must be replaced with a running brake function. If the running brake function is not used, there will be a knocking sound when the door is closed. As the pulling force of the tension spring is getting smaller and smaller, it must be related to door-closing speed compensation function, there will be no too hard closing speed curve. To have a perfect closing curve, the door speed compensation function is required.
2. Counterweight type automatic door closing: Opening the door requires a greater torque to open the door. When the door is in place, it is affected by the counterweight pulling back, and the door pulls backwards. At this time, the elevator door motor must not move. Torque can keep the elevator door fixed in position. Closing the door is the opposite. Affected by the free fall of the counterweight, the elevator door machine motor must be trasformed into a running brake function to prevent inertial impact when the door is in place.
3. Closing torsion: when the car is about to leave the floor, the inner and outer doors are closed, and the elevator door machine motor must be turned into a stationary torque to keep the car door from being affected by external forces. These are the elevator's safety regulations.
4. Opening torsion: When the car arrives on the floor, in order to enable people to enter and exit without obstacles, the elevator door machine motor must be turned to open the door to complete the torque at this time, and this is the function of the elevator.