The development history of magnetic suspension bearings

In recent years, with the continuous development of magnetic levitation-related disciplines such as electromagnetics, electronics, control theory, mechanics, rotor dynamics, materials science, and computer science, maglev-related products and applications have continued to expand, and it can be said that it has entered an explosive period. Taking the hyperloop as an example, there are various technical routes, such as Japan's low-temperature superconducting (such as MLX01, L0 and other maglev trains), China's high-temperature superconducting (such as the vacuum pipeline high-temperature superconducting maglev test system 'Superconductor' researched by Southwest Jiaotong University. -Maglev'), Germany's electromagnetic force (TR01-TR09 series of maglev trains, etc.), and Musk's vacuum high-speed rail plan (Hyperloop system), etc. Maglev has become an underlying innovation that can directly or indirectly drive a large number of related industries. 'Magnetic bearing is a new type of high-performance bearing that uses magnetic force to suspend the shaft and load in space without mechanical friction and without lubrication.' As a new modern support technology, magnetic suspension bearing, we simply sort out the development. 1. History of Development In 1842, Eamshaw of Cambridge University, UK, proposed the concept of magnetic levitation and proved that it is impossible for a ferromagnet to be supported by another permanent magnet and maintain free and stable suspension in all six degrees of freedom. At least one degree of freedom must be eliminated by mechanical or other constraints. After nearly a century of research and other scientific and technological developments, in 1937, Kemper applied for a patent on levitation bearings, which constituted the leading idea for subsequent research on maglev trains and maglev bearings. In 1938, Kemper used an inductive sensor and a tube amplifier to make a controllable electromagnet, and successfully achieved a stable magnetic levitation on an object weighing 2 100 N, which was the prototype of a maglev train. During the same period, Beams and Holmes of the University of Virginia in the United States used electromagnetic levitation technology to suspend a small steel ball, and measured the strength of the test material by the centrifugal force that the steel ball could withstand when rotating at a high speed. The rotation speed is as high as 1.8x106 r/min, which may be the earliest application example of using magnetic levitation technology to support rotating objects in the world. With the rapid development of modern control theory and electronic technology, from the early 1960s, the international magnetic suspension bearing was the first to be applied in space technology. The Draper Laboratory in the United States first successfully used magnetic suspension bearings in space guidance and inertia wheels. In 1969, the French military scientific research laboratory began to study the magnetic suspension bearing, and in 1972, the first magnetic suspension bearing was used for the support of the satellite guide wheel. After the 1960s, the United States, Japan, France, the former Soviet Union and other countries began to carry out research work on active maglev bearings. The work in this period laid a theoretical foundation for future practice. After the 1970s, with the emergence of large-scale integrated circuits, new permanent magnet materials and the urgent need for scientific and technological development, magnetic levitation technology has developed rapidly and has been applied in many fields, such as various high-speed rotating machinery in the machinery industry, including various Machine tools, turbomolecular pumps, high-speed centrifuges, turbogenerators, liquid helium pumps, etc. In 1977, the Lincoln Laboratory of the Massachusetts Institute of Technology designed and manufactured a magnetic bearing for the momentum or energy storage flywheel of a spacecraft. In 1976, the S2M company jointly invested by the French SEP company and the Swedish SKF bearing company, launched the B20/500 maglev spindle system for the first time at the Hanover European International Machine Tool Exhibition in 1981, and carried out a field test at 35 000 r/min. Drilling and milling performances, the company also exhibited a series of magnetic bearings and their supported machine tool spindle components at the 5th European Machine Tool Exhibition in 1983. In 1983, a vacuum pump with magnetic bearing was installed in the European space capsule of the American space shuttle. In 1986, Japan conducted a space test of a maglev flywheel on the H-1 rocket. In 1994, Meeks and others designed two generations of magnetic suspension bearings for aero-engines. Around 1997, the Draper Laboratory in the United States reported a series of research results on high-temperature magnetic suspension bearings for aero-engines, and successfully developed a magnetic suspension bearing system that can work at a high temperature of 510 °C. Experiments were successfully carried out on the model rotor of the engine. 2. Domestic research situation Domestic research on maglev bearing technology began in the early 1980s.