Introduction to elevator traction system

Elevator traction system is the core power device for the vertical lifting of the elevator. It drives the car and counterweight to run by means of the friction between the traction wheel and the traction rope. The following is a detailed introduction to the composition, principle, advantages and safety points of the elevator traction system.

I. System composition

1.traction machine

①Function: As the power source of the traction system, it is responsible for driving the rotation of the traction wheel.

②Classify:

        Permanent magnet synchronous traction machine: with the characteristics of energy saving and low noise, no gearbox is required, high transmission efficiency, is the current mainstream choice.

        Asynchronous traction machine: It needs to be used with a gearbox. It was more common in the past, but has been gradually replaced by permanent magnet synchronous traction machine.

③Key components: including motor, brake (brake), traction wheel, etc. Among them, the brake can play a braking role when the elevator stops to prevent the car from rolling.

2.Pulled wire rope

①Function: used to connect the car and counterweight, through the friction of the traction wheel to transmit power.

②Features: generally composed of multiple steel wire ropes, with high strength and wear resistance, and equipped with wire break detection and tension balance device to ensure safety.

③Pulling ratio: refers to the ratio of the running speed of the traction rope to the running speed of the car. Common ones are 1:1 (the traction rope is directly suspended from the car, and the speed is the same) and 2:1 (the traction rope is reduced by a pulley group, and the speed of the traction rope is twice that of the car).

3.Guide wheel and counter rope wheel

①Guide wheel: installed on one side of the traction machine, the main function is to change the direction of the traction rope, so that the car and counterweight can run vertically.

②Anti-rope wheel: used when the traction ratio of the elevator is greater than 1, it can adjust the winding of the traction rope, thus changing the relative position of the car and counterweight.

II. Working principle

1.Friction drive: the traction machine drives the traction wheel to rotate, and the friction between the traction wheel groove and the traction rope pulls the elevator car and counterweight to do relative motion. For example, when the elevator car rises, the counterweight will fall, and vice versa.

2.Balance of force: The weight of the counterweight is usually 40% -50% of the weight of the car plus the rated load. Its function is to balance the weight of the car and reduce the power consumption of the traction machine.

3.Speed control: the speed of the elevator is controlled by adjusting the speed of the traction machine through the frequency converter, so that the elevator can start, accelerate, run at a constant speed and decelerate smoothly.

III. Main advantages

1.Safety and reliability: Relying on friction transmission, when the elevator is overloaded or slipping, the protection mechanism will be triggered to avoid danger. At the same time, the design of multiple steel wire ropes realizes redundant safety, even if some steel wire ropes fail, the rest can still maintain the operation of the elevator.

2.High efficiency and energy saving: the permanent magnet synchronous traction machine does not need excitation current, high power factor, compared with the traditional asynchronous traction machine energy saving more than 30%.

3.Compact structure: no need to set up the top drive room (no machine room elevator), can save building space, reduce civil construction costs.

4.Smooth operation: using frequency conversion speed control technology and high precision mechanical parts, can effectively reduce the vibration and noise of elevator operation.

IV. Safety and maintenance points

1.Steel wire rope maintenance: it is necessary to check whether the steel wire rope has wear, broken wires, rust and other conditions regularly, and lubricate according to the regulations. At the same time, adjust the tension of each steel wire rope to keep it consistent.

2.Brake maintenance: to ensure that the action of the brake is flexible and reliable, regularly clean the brake brake, check whether the braking clearance meets the requirements, and prevent the elevator from rolling due to brake failure.

3.Elevator wheel inspection: Check the wear of the elevator wheel groove. If the depth is not uniform or the groove wear exceeds the specified value, repair or replace it in time.

4.Anti-jump device: In high-speed elevators, anti-jump devices are usually set up to prevent the elevator from running away from the traction wheel due to the jumping of the steel wire rope.

V. Application scenarios

Elevator traction is widely used in residential buildings, office buildings, shopping malls, hotels and other architectural scenes, especially suitable for the promotion of high-rise buildings. At present, more than 90% of the vertical elevator on the market adopts the traction drive mode.