Viscosity Control of Magnetorheological Fluid by Power Saving Magnetizing Mechanism Using Movement of Permanent Magnet

Generally, the magnetic field applied to a magnetorheological fluid (MRF) is generated by electromagnets. Electromagnets consume electric power during MRF magnetization, which is an issue. In this study, we examine two kinds of magnetizing mechanism using a permanent magnet, instead of electromagnets, to save electric power and generate a magnetic field on the MRF. One mechanism linearly moves the permanent magnet into the magnetic circuit composed of yokes. The magnetic field intensity on the MRF is then controlled by changing the overlap between the magnet and the yokes. The other mechanism rotates a permanent magnet in the magnetic circuit. The magnetic field intensity on the MRF is then controlled by changing the relative angular position between the magnet and the yokes. These two mechanisms normally generate force or torque on the magnet toward a magnetically stable position concerning the magnet, and the force or torque causes power consumption to hold and move the magnet. We design herein special magnetic circuits and a cancelation mechanism for the force or torque that drastically reduce the power consumption during the MRF magnetization compared with an electromagnet-type magnetizing device.