In 1967, thyristors were used to drive elevators, and elevators controlled by AC voltage and speed drives appeared. In 1983, elevators with variable voltage and frequency control appeared, and quickly became mainstream products for elevators due to their good speed regulation performance, comfort, and energy saving.
In 1996, the machine-room-less elevator driven by AC permanent magnet synchronous gearless traction machine appeared, and the elevator technology was another innovation. Because the traction machine and the control cabinet are placed in the hoistway, the independent machine room is omitted, the construction cost is saved, the effective area of the building is increased, and the freedom of design of the building’s architectural aesthetics is improved. This elevator also has the characteristics of energy saving, no oil pollution, maintenance-free and high safety.
The development of elevator control methods has gone through processes such as handle switch operation, button control, signal control, and collective selection control. Parallel control and intelligent group control have appeared for multiple elevators.
Nowadays, elevator companies from all over the world are constantly researching and developing new elevator products and improving their maintenance and service systems, and strive to meet people’s increasing demand for modern construction and transportation.
In 1852, the home escalator suppliers engineer Elisha Graves Otis (1811 ~ 1861) invented the world’s first safety lift in Yonkers, New York, USA. It is a lift powered by a steam engine and equipped with safety devices. He fixed the jagged iron bar on the guide rail, set a spring leaf on the upper part of the car, and connected it with the mechanical linkage and the brake pawl. The traction rope is fixed in the center of the spring piece. When the traction rope breaks, the spring piece returns to its original shape, forcing the mechanical linkage to move, and then the brake claws extend into the jagged iron bar to prevent the elevator from falling. Industrial users (cargo lifts) are the first users of safety lifts.