Introduction to elevator door system

As the core component of elevator safety operation, the elevator door system is mainly composed of car doors, floor doors, door machines, door locks, light screens, etc., which work together to realize passenger access control and safety protection. The following is an introduction from the aspects of technical evolution, core functions, safety mechanisms and the latest development:

I. System composition and driving technology

Core components

Car door and floor door: The car door is located inside the elevator, and the floor door is installed on each floor. The two doors are mechanically linked through the door lock to ensure that they open and close synchronously when the elevator stops.

 Door System: Responsible for driving the movement of doors, it has undergone technological iterations from mechanical door systems to variable frequency door systems and finally to permanent magnet synchronous door systems. The current mainstream permanent magnet synchronous door systems use rare earth permanent magnet motors combined with variable frequency control technology, offering advantages such as energy efficiency, low noise, and long lifespan. Compared to traditional asynchronous motors, they achieve an efficiency improvement of over 30%. For example, the rack-and-pinion transmission solution mentioned in Zhejiang Elevator's 2025 patent further enhances durability and maintenance convenience by replacing traditional synchronous belts.

drive control

The portal mechanism achieves closed-loop control through an encoder, accurately monitoring the position and speed of the door to ensure smooth and stable operation. Some high-end systems incorporate brushless motor force feedback technology, which can detect closing resistance in real time. When the clamping force exceeds 150N, it automatically reverses to open the door. Additionally, the design with flexible touch sensors enhances sensitivity for detecting small foreign objects (such as hair or pet strings).

II. Safety protection mechanism

Multiple locking and electrical interlocking

The floor door uses a bistable mechanical lock hook, which is combined with the door lock relay of the elevator car door to form a "mechanical + electrical" double protection. According to the revised requirements of GB7588-2003, the floor door needs to withstand a static force test of 300N to ensure that it remains intact under accidental impact.

The door contact switch is directly linked to the elevator control system. The elevator can only start running when all doors are locked and the door contact signal is normal.

Screen and safety touch panel

Light screen: A dense light grid is formed by more than 32 sets of infrared transmitting/receiving tubes. When any beam is blocked, the door opening signal is triggered within 0.1 seconds, and obstacles with a minimum diameter of 3mm can be detected.

Safety touch plate: physical contact protection, forced door opening through microswitch after triggering, and redundant protection with light screen. Some systems combine AI image recognition technology to distinguish passengers from fixed obstacles, reducing false triggering.

Emergency rescue design

The door is equipped with a special triangular keyhole, which can be manually unlocked by rescuers in case of emergency. The top of the elevator car is equipped with an emergency electric door opening device, which can still open the door of the elevator car by manual turning when the power is cut off.

III. Types and application scenarios

Common door types

Middle door: symmetrical opening on both sides, small space occupied, suitable for passenger elevator and residential elevator, the switching speed can reach 0.3-0.6m/s.

Side door: the door panel folds to one side, saving the width of the shaft. It is mostly used in commercial buildings or villa elevators with limited space.

Double-fold door: divided into two folds to contract, suitable for large elevator cabins and freight elevators, which can achieve a larger door width in the limited shaft.

Special needs design

The medical elevator adopts a wide middle door to facilitate the stretcher in and out; the clean room elevator is equipped with a gas-tight door to reduce air flow disturbance; the fireproof elevator floor door needs to pass the GB/T 27903-2011 fire resistance test, and the fire resistance limit is not less than 1 hour.

IV. Intelligence and Internet of Things upgrade

Real-time monitoring and early warning

The Internet of Things system collects data such as door machine vibration, current and door opening and closing time through sensors, and realizes fault prediction by combining big data analysis. For example, the torque fluctuation of brushless motor is used to identify door guide rail wear, and maintenance reminder is issued 72 hours in advance.

The cloud platform can remotely monitor the elevator status, automatically dispatch orders and push rescue information to the mobile phone of maintenance personnel when abnormal, and the average response time is shortened to 15 minutes.

Human-computer interaction optimization

Some high-end elevators are equipped with capacitive touch buttons and light screens to automatically open the door when passengers approach the door area; the voice prompt system can broadcast the door status to assist visually impaired people to ride the elevator safely.

V. Maintenance and standards

Daily maintenance points

Clean the light screen transmission/reception window every quarter to avoid dust affecting the detection accuracy; lubricate the door machine gearbox every year, and replace the worn synchronous belt or chain.

According to GB 55037-2022 "General Code for Fire Protection of Buildings", the fire resistance performance of floor doors should be regularly tested by a third party to ensure that smoke and flame can be effectively blocked in case of fire.

In line with international standards

China's current standard GB7588-2003 has integrated the EU EN81-20/50 requirements, strengthening the protection of unexpected movement of the elevator car (UCMP), requiring the elevator to stop and remain locked within 1.2 meters when there is no command movement in the unlocking area.

The elevator door system is continuously evolving towards "safety,efficiency, and intelligence." From mechanical protection to IoT empowerment, technological innovations are constantly enhancing the elevator experience and reliability. In the future, with the deep integration of AIand5G technology, door systems may achieve more precise behavior prediction and personalized services, further driving the intelligent upgrade of the elevator industry.