Patent ID: 6933642
Filing Date: 2005-08-23
Classification: F16C,G11B,H02K

Abstract:
1. A hydrodynamic gas bearing comprising: a rotatable cylindrical hub with an internal circumferential face of a circular cross-section; a supporting shaft inserted in said cylindrical hub for maintaining a predetermined clearance form said internal circumferential face, to rotatably support said hub to allow its rotation; an annular thrust bearing plate attached to said hub in opposed spaced relationship to an end face of said supporting shaft, for generating a supporting force to support said hub in an axial direction of said supporting shaft when said hub rotates in a predetermined direction; a projection which is projected from said end face of said supporting shaft through a hole in said annular thrust bearing plate; a thrust flange fixed to said projection and having a flange portion opposing to and spaced from said thrust bearing plate; a fixing frame on which said thrust flange is mounted; a rotation driving unit mounted on said fixing frame for supplying a rotative force to a member to be driven attached to said hub; at least one first permanent magnet attached to said supporting shaft, said first permanent magnet including a third permanent magnet and a fourth permanent magnet each of which have magnet poles in the axis direction of said supporting shaft and are mounted on an end portion of said supporting shaft in spaced relation to each other; and at least one second permanent magnet attached to said hub in opposed spaced relationship to said first permanent magnet and magnetized so as to generate a repulsive force against said first permanent magnet, said second permanent magnet including a fifth permanent magnet which is mounted on said hub in opposed spaced relationship to said third permanent magnet and has magnetic poles in a direction so as to separate a repulsive force against said third permanent magnet, and a sixth permanent magnet which is mounted on said hub in opposed spaced relationship to said fourth permanent magnet and has magnetic poles in a direction so as to generate a repulsive force against said fourth permanent magnet; wherein