Research Points To Hot Magnetic Bearings

Electron Energy Corporation (EEC), one of the world's leading producers of rare earth magnets and magnet systems, has been awarded a Small Business Innovation Research (SBIR) Phase II contract by NASA to continue researching high temperature magnetic bearings technology. NASA's Glenn Research centre (GRC), Cleveland, Ohio, selected EEC to receive the $600,000 contract for development until November 2007. EEC will team with Texas A and M University (TAMU) to complete the project. This research programme will use advanced high temperature permanent magnet (HTPM) technology to provide higher efficiency and reliability for high temperature magnetic bearings, reduce the required electronics significantly, and extend the operating temperature to 550C. The proposed 'universal' test facility will also provide a convenient test bed for future prototype high temperature bearings, motors, generators, backup bearings and sensors. Spinoffs from this work may include ultra-high-temperature solenoid type actuators for valve and flight surface applications in the aerospace, energy and petrochemical industries. In Phase I, EEC and TAMU designed, built and tested a high temperature magnetic bearing prototype using EEC's patented SmCo UHT material, which has a load capacity of 230kg at 550C. Phase I lasted from January to July of 2005. The technical objectives of Phase II are: to develop permanent magnets with increased high temperature structural and magnetic strengths; design and produce a high temperature, permanent magnet biased, homopolar fault tolerant combination bearing; develop a universal test platform for testing prototype motors, generators and magnetic bearings at ultra-high temperatures and speeds; and develop backup bearings that will operate reliably at 550C. Magnetic bearings could increase the reliability and reduce the weight of engines by eliminating the lubrication system. Research in high temperature magnetic bearings has focused on unique designs using electromagnets because conventional permanent magnets would not be able to perform at high temperatures. However replacing the electromagnets with the EEC HTPM technology will yield magnetic bearings with greater stability, reliability and efficiency, and decrease their size and weight. High temperature magnetic bearings operate at elevated temperatures, higher rotational speeds, and extreme altitudes. 'High temperature magnets are suitable for long-term service at temperatures as high as 550C, and can be used in a wide variety of aerospace applications', said Michael H Walmer, President of EEC. High temperature bearing systems will help NASA produce lighter weight and higher temperature gas turbine engines and integral generators, which are more efficient and decrease noise and emissions. NASA will also gain lighter weight, higher temperature machinery that operates effectively in hostile, high temperature environments such as the surface of Venus, and can perform space-based power generation and energy storage. This technology and test capability will benefit the aerospace and process machinery industries by aiding the development of more compact, lubricant-free rotating machinery and components. High temperature magnetic bearings will enhance the performance of new generation aircraft gas turbine engines, which need bearings that operate continuously at high temperatures. Bearing assemblies must supply damping to stabilise rotor dynamic vibrations along with providing support. Conventional bearing/dampers, which use oils or elastomers will not operate at these high temperatures. Applications include uses in turbines and turboexpanders used in the chemical processing industries. Since 1996, EEC has received 15 STTR or SBIR Phase I and Phase II program contracts, which resulted in three patents, as well as over 20 papers published in professional journals.