Nowadays, elevator technology is developing rapidly, and elevator factories produce different types of elevators for different building needs. Common ones include traction elevators, hydraulic elevators, and screw elevators, but traction elevators are the most mainstream. Today, let me tell you what a traction elevator is? The characteristics and safety design of traction elevators.
Three major types and principles of elevators
There are actually three main ways for elevators to rise:
- The first: pulling with the help of a rope, called a “traction elevator”;
- The second: relying on the hydraulic principle, using a “rod” to push the car up, that is, a “hydraulic elevator”;
- The third: using a screw to drive, called a “screw elevator”.
It is not difficult to find that although the latter two are simple in structure, they are only suitable for use in low-rise buildings due to the physical limitations of the rod length. At the same time, they have not been widely used due to the wear, noise and high operation and maintenance costs caused by direct contact between components. In contrast, traction elevators almost dominate high-rise buildings due to their higher operating efficiency and larger rated load.
Core technical features of traction elevators
Traction elevators are driven by motors, and the car is driven up and down by steel wire ropes. However, in order to avoid excessive energy consumption and unnecessary wear of steel cables, engineers have added an important component-the counterweight system.
Simply put, it is to add a counterweight block to one side of the elevator, so that the force required for the car to move up and down is greatly reduced.
The design of the counterweight directly affects the performance of the elevator, and is generally matched according to the weight of the car plus half to 40% of the rated load. For example, if an elevator weighs one ton and has a rated load of one ton, the counterweight is usually set at around 1.4 to 1.5 tons. However, if the counterweight is too heavy, such as equal to or even exceeding the total weight, it will lead to a safety hazard of the elevator rushing to the top after a power outage. Therefore, traction elevators also need to use special mechanical safety designs to prevent this situation.
Price range of traction elevators
The price of traction elevators on the market currently ranges from tens of thousands to hundreds of thousands. The specific cost will be affected by many factors, such as the brand, model, size and installation environment of the elevator. If you have completed the civil engineering reservation, it will be relatively more economical to install a closed elevator.
Why has the permanent magnet synchronous traction machine become the mainstream?
In the early elevator design, the asynchronous motor plus worm structure was a common choice. Although it can ensure that the elevator does not fall in the power outage state and will not hit the top due to inertia, it is gradually eliminated because the worm is prone to wear and tear in long-term operation and the subsequent maintenance is complicated. Today, the more miniaturized permanent magnet synchronous traction machine has become the mainstream solution. Because of the design of the permanent magnet, the magnetism of this motor can still be partially retained even if the power is off, thus playing a role of stable protection, eliminating the cumbersome mechanical structure, and greatly improving the safety and energy efficiency performance.
Anti-fall safety design of traction elevators
In addition to the traction system itself, the elevator has specially developed a multi-layer safety design for anti-fall.
Typically, traction elevators use four to eight steel ropes, each of which has a carrying capacity that exceeds the mass of a fully loaded car. Even if only one is left, it can maintain basic operation.
However, engineers have taken into account extreme conditions, such as the risk of all steel cables breaking. At this time, the guide rails on both sides of the car can work, with three wheel sets and brakes attached to each side. When the height drops unexpectedly or falls at an excessive speed, the high-speed regulator activates the corresponding steel cable through the centrifugal lock, thereby triggering the brake and forcibly stopping the car. At the same time, the bottom and top of the elevator are also equipped with an amplitude elimination function (hydraulic shock absorber), which can prevent the car from directly colliding and losing control even if the overspeed brake fails.
After countless years of development, traction elevators have become a complex system with multiple safety measures. Whether it is the expanded and optimized counterweight design, the mainstream permanent magnet synchronous traction motor, or the upgraded anti-fall technology, all designs are designed to ensure that people can be safer when riding the elevator.
