Development and evaluation of the magnetic and journal bearing saving electric power using permanent magnet and ER fluid.

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Bearing is an important machine element, which supports rotating machinery. It is an inevitable problem to reduce the friction loss, while the performance of the bearing is kept. So we tried development and evaluation of the electric power saving bearings using ER fluid (LC ; Liquid Crystal) as a lubricating fluid of journal bearing, and permanent magnet as elements in magnetic bearing. The objective of this research is to clarify the energy saving performance of LC journal bearing and to examine the possibility of realizing a permanent magnetic bearing.In order to clarify the basic characteristics of LC journal bearing, the measurement of bearing properties by applying voltage between journal and bearing was carried out. We clarified that the same load capacity can be obtained with friction torque reduced maximum of 40%, and that the locus of journal center differs from the conventional bearing. The principle was that the viscosity of LC increased in the minimum film thickness area locally.The method of applying voltage partially using distributed electrodes was proposed for the purpose of increasing load capacity with suppressing the increase of friction torque. The results were that the same load capacity can be obtained with still lower friction torque compared with the case of using single electrode, and that the journal center is controllable in the limited area. From the measurement of friction torque, upstream region of the pressure increasing toward flow direction is the best location for applying voltage to minimize friction torque.We designed the magnetic bearing only using permanent magnet. We clarified the arrangement of the magnet to support the rotating shaft only by permanent magnet. However, the bearing has not come to a realization.