| 摘要 |
PROBLEM TO BE SOLVED: To drastically reduce an eddy currents that are generated at the rotor of a magnetic bearing and to suppress heat generation and temperature increase in a spindle, by constituting a fixed side stator part of a radial bearing with a plurality of magnetic poles, and setting the shape of the boundary line between the magnetic poles facing a rotary shaft at right angle or at an inclination angle to the axial direction of the rotary shaft. SOLUTION: A stator 5 is composed of eight magnetic poles 23, and a coil winding 22 is executed to each magnetic pole. Also, it is arranged so that a gap δ between magnetic poles on the inner surface (a side that faces a spindle) can be maintained, and the magnetic pole of the magnetic bearing is twisted by an angle of α for the axial direction. The density of an eddy current being generated at the rotor of the magnetic bearing is proportional to the amplitude of the change amount of the magnetic density. Therefore, an eddy current loss that is consumed by the rotor is proportional to the square of the current density, namely the square of the amount of change of the magnetic density. By twisting the shape of the magnetic pole with respect to the shaft, the magnetic density changes with a gentle slope when the rotor changes from N to S or from S to N, thus drastically reducing heat generation by suppressing the generation of the eddy current losses. |
