Patent ID: 8203243
Filing Date: 2012-06-19
Classification: F16C

Abstract:
1. An electromagnetic attraction type magnetic bearing comprising: (a) at least a pair of electromagnets arranged to face each other; (b) a float arranged between the electromagnets and held at the middle position thereof; (c) a sensor for detecting a displacement of the float from a balance position, or a speed of the float, or the displacement of the float from the balance position and the speed of the float; and (d) a controller for controlling the electromagnets, wherein the pair of electromagnets comprises a first electromagnet and a second electromagnet, and when displacement directed to the first electromagnet from the balance position of the float is defined as x, the speed v of the float is defined as v=dx/dt, and γ is defined as a positive constant, and wherein the controller determines a variable Z proportional to acceleration in the control direction based on the displacement and the speed of the float by the following Equation (A), and the controller operates to set a control current of one electromagnet of the pair of the electromagnets to zero and to control only a control current of the other electromagnet of the pair of the electromagnets, depending on positive and negative values of the variable Z in cases including wherein (i) x≧0, v≧0; (ii) x≧0, v<0; (iii) x<0, v<0; and (iv) x<0, v≧0.