The origin of the elevator

Ladder origin

Elevator is an indispensable vertical transportation equipment in modern multi-storey and high-rise buildings. As early as 1100 BC, China's ancient zhou dynasty witnessed the emergence of a simple windlass for carrying water, a simple hoist consisting of wooden (or bamboo) supports, rolls, cranks and ropes. In 236 BC in ancient Greece, famous scientist Archimedes made the first human-driven drum hoist. These are the prototypes.

When watt invented the steam engine in 1765, in 1835 Britain installed an elevator driven by it in a factory. In 1845, Neil Armstrong, a British man, built the first hydraulic elevator, a precursor to the modern hydraulic elevator.

In the early stage, the elevator mainly used drum lifting, pulling of cotton and linen rope, and breaking of rope falling accident, so the development of the elevator was tested by the safety. In 1852, Otis, a 41-year-old American, invented a safety clamp that locks the car onto the guide rail when the sling breaks, preventing it from falling. Since then, there has been a significant change in the old lift. In 1854, at the "crystal palace" exhibition in New York, Otis personally performed the performance of the safety clamp, he stood on the high lift platform, then cut the sling, in the audience's surprise, the platform was firmly bitten by the safety clamp, Mr. Otis walked off the platform safely. From this beginning, the safety of the anti - fall of the elevator has a reliable guarantee.

The fundamental reason for the prosperity of modern elevator lies in the use of electricity as the power source. Faraday invented the dc generator in 1831. In 1880, the first electric hoist appeared in Germany, and a universal vertical transport machine called the elevator was born. Although the elevator is fairly crude and simple from today's perspective, it is a milestone in the elevator's history.

In 1889, the first batch of elevators were installed in the "dynast" hall in New York, USA. They were directly connected by the direct current motor and the worm drive. Through the elevator car of the reel, the speed was 0.5m/s, forming the basic transmission structure of modern elevators.

Although the tractor-driven structure appeared in Britain as early as 1853, the disadvantages of the reel drive were not fully recognized at that time, so the early elevator was mainly driven by the drum. With the development of technology, the disadvantages of drum drive are increasingly obvious, such as high power consumption, short travel and poor safety. In 1903, Otis elevator company changed the elevator with reel drive to traction drive, which laid the foundation for today's long journey elevator. From then on, traction drive dominated the way of elevator drive. The traction drive greatly reduces the volume of the transmission mechanism, and also effectively improves the versatility and safety of the elevator traction machine in the structural design.

Since the beginning of the 20th century, the ac induction motor has been further perfected and developed, and it has been applied to the elevator driving system, which simplifies the system and promotes the popularization of the elevator. To this day, most elevators with speeds below 2.5m/s in the world are driven by ac motors.

In the 1930s, the American Otis elevator company installed 74 elevators in the 102-story skyscraper in New York by using the direct-current generator-motor mode, among which the maximum rated speed was up to 6m/s. Westinghouse also installed 75 elevators in 1937 at Rockefeller center on the 70th floor of New York, with a maximum rated speed of 7m/s.

2. Evolution of elevator control technology

In the early stage, almost all the control methods of elevators were controlled by the driver's intra-car switch, and the judgment of starting, running, decelerating, leveling and stopping of elevators was made by the driver, which was very inconvenient to operate. In 1894, Otis developed a technology to automatically control the flat floor by a floor controller, thus becoming a pioneer in the development of elevator control technology.

In 1915, Otis company invented the microdrive flat layer control technology controlled by two motors. It is used for starting and running with one motor and stopping with the other motor. Thus, the deceleration range of 16-1 is obtained.

In order to solve the problem of passenger waiting time, a set selection control technique was developed in 1925. It can make the elevator operate reasonably, shorten the waiting time of passengers and improve the efficiency of the elevator operation by comparing the call signal from the upper and lower directions of each floor station with the command set in the car and the elevator position signal. This technology greatly simplifies the operation of the driver. It no longer requires the driver to judge the operation direction of the elevator and the choice of stopping floor. The driver only needs to press the floor button and close the door button. This kind of control technology is still widely used, which is regarded as a great progress of elevator control technology.

In the 1930s, ac induction motors were widely used in elevators because of their low price, convenient manufacture and maintenance. By changing the pole-logarithm of the motor, the requirement of double speed control is achieved, the system structure is simplified and the reliability is improved greatly. At present, most of the elevators in China use this kind of alternating current variable pole drive control.

In the early days, after the development of ac single-speed and double-speed drive, with the development of high-rise buildings in the 1930s, people's requirements on the rated speed of the elevator increased day by day, resulting in a high-speed elevator controlled by dc speed regulation. The system has developed from the initial open-loop, stepped and contactless control to today's closed-loop, stepless and contactless control system. This is another advance in elevator control technology.

With the development of electronic technology, from the late 1960s to the early 1970s, the application of ac motor's ac speed regulating drive began to be developed. It completely replaces the dc drag system with its outstanding energy saving effect within a certain range (less than 4m/s). This is the technology that is developing energetically at present, be regarded as elevator to drag a technology to leap.

With the rapid development of microelectronic technology, microcomputer is used in elevator control, replacing relay control with contact. So that the elevator drag control, signal operation and automatic control to a new height. Nowadays, the large number of applications of microcomputer and the technology development of high-power semiconductor components make the elevator control system more and more automatic and intelligent, and the ac frequency and voltage regulation technology is also developing in the direction of high power and high speed. At present, the development of this technology has made the speed of ac speed-driven elevator reach 7m/s, which will gradually replace the dc driven elevator.