Patent ID: 6657343
Filing Date: 2003-12-02
Classification: F16C,H02K

Abstract:
A magnetic fluid bearing motor provided with a bearing assembly, the bearing assembly comprising:a shaft formed partly or wholly of a ferromagnetic substance; a substantially solid porous sleeve faced in parallel with the shaft forming a bearing portion with a minimum gap provided therebetween; and magnetic fluid oil impregnated into the gap and the porous sleeve, wherein a ferromagnetic substance included in the shaft is locally magnetized so as to create magnetic flux density gradient that is set at a maximum along the bearing portion of the porous sleeve and decreases gradually as it stays away therefrom, wherein a boundary of a magnetization-varying portion of the shaft is aligned with a line of a flow of the magnetic fluid oil occurring with rotary motion of the sleeve or the shaft, and wherein the bearing portion has a groove for generating dynamic pressure formed on a surface of the shaft or the sleeve, and a magnetization-varying portion is arranged in a position of the shaft that corresponds to the groove.