Active Magnetic Bearings
HISTROY
The evolution of active magnetic bearings may be traced through the patent issued in this field. Earlier patents for magnetic suspensions can be found but are excluded here because they consist of assemblies of permanent magnets of problematic stability per Earns haw’s Theorem. Early active magnetic bearing patents were assigned to Jesse beams at the university of Virginia during World War II and are concerned with ultracentrifuges for purification of the isotopes of various elements for the manufacture of the first nuclear bombs, but the technology did not mature until the advances of solid-state electronics and modern computer-based control technology with the work of Hagerman and Schweitzer. Extensive modern work in magnetic bearings has continued at the University of Virginia in the Rotating Machinery and Controls Industrial Research Program. The first international symposium for active magnetic bearing technology was held in 1988 with the founding of the International Society of Magnetic Bearings Since then there have been nine succeeding symposia. Kasarda reviews the history of AMB in depth. She notes that the first commercial application of AMB’s was with turbo machinery. The French company S2M, founded in 1976, was the first to commercially market AMB’s.
INTRODUCTION
Active magnetic bearings (AMB) have been designed to overcome the deficiencies of conventional journal or ball bearings. A bearing is a machine element, which supports another moving machine element. It permits relative motion between the contact surfaces of the members, while carrying load. Due to relative motion, friction occurs and rubbing surface wears rapidly. To prevent this lubricant may be used.
A question comes in mind whether it is possible to support a journal without any physical contact so that there is no wear. Is there a force, which can exert even if there is no contact between two-surfaces? Magnetic force allows such property and thus the idea of magnetic bearing
The evolution of active magnetic bearings may be traced through the patent issued in this field. Earlier patents for magnetic suspensions can be found but are excluded here because they consist of assemblies of permanent magnets of problematic stability per Earns haw’s Theorem. Early active magnetic bearing patents were assigned to Jesse beams at the university of Virginia during World War II and are concerned with ultracentrifuges for purification of the isotopes of various elements for the manufacture of the first nuclear bombs, but the technology did not mature until the advances of solid-state electronics and modern computer-based control technology with the work of Hagerman and Schweitzer. Extensive modern work in magnetic bearings has continued at the University of Virginia in the Rotating Machinery and Controls Industrial Research Program. The first international symposium for active magnetic bearing technology was held in 1988 with the founding of the International Society of Magnetic Bearings Since then there have been nine succeeding symposia. Kasarda reviews the history of AMB in depth. She notes that the first commercial application of AMB’s was with turbo machinery. The French company S2M, founded in 1976, was the first to commercially market AMB’s.
INTRODUCTION
Active magnetic bearings (AMB) have been designed to overcome the deficiencies of conventional journal or ball bearings. A bearing is a machine element, which supports another moving machine element. It permits relative motion between the contact surfaces of the members, while carrying load. Due to relative motion, friction occurs and rubbing surface wears rapidly. To prevent this lubricant may be used.
A question comes in mind whether it is possible to support a journal without any physical contact so that there is no wear. Is there a force, which can exert even if there is no contact between two-surfaces? Magnetic force allows such property and thus the idea of magnetic bearing
References: 1. .www.wikipedia org/wiki/Magnetic barring 2. Active magnetic bearing- chances and limitations, G Schweizer International Centre for Magnetic Bearing, ETH Zurich, CH-8092, Zurich 3. Kim & W.J.Yand,”Rotating Machinary” 4. G.Schweitzer, H.Blueler & A,Traxler,”Active Magnetic Bearings” 5. Neale M.J. ”Tribology Handbook”