Patent ID: 6072660
Filing Date: 2000-06-06
Classification: F16C,G11B,Y10S

Abstract:
An oil lubrication dynamic pressure-type bearing device for a disk driving apparatus, comprising:a housing main body;a sleeve fixed with respect to said main body;a rotor that is relatively rotatable with respect to said main body;a shaft that is fixed with said rotor, said shaft having a spherical front end;a bottom plate secured with respect to said sleeve so as to face said front end of said shaft;a dynamic pressure radial bearing between said sleeve and said shaft comprising herringbone grooves at either of said shaft and said sleeve;a thrust pivot bearing providing axial support between said shaft and said sleeve;a common lubricating fluid at said dynamic pressure radial bearing between said sleeve and said shaft and at said thrust pivot bearing, said dynamic pressure radial bearing being in fluid communication with said thrust pivot bearing;wherein said sleeve and said bottom plate substantially enclose a space around said thrust pivot bearing, said space being filled with said lubricating fluid;wherein said front end of said shaft is an R-form;wherein said shaft has an intersecting outline part of the R-form of said front end and a peripheral part adjacent thereto;wherein said sleeve has an inner diameter adjacent to said front end of said shaft that is sufficiently large such that said intersecting outline part and said peripheral part adjacent thereto do not overlap any of said herringbone grooves;wherein said R-form of said front end of said shaft has a radius of curvature r;wherein said intersecting outline part is spaced a distance x from the closest of said herringbone grooves;wherein said sleeve has a cylindrical part adjacent to said front end of said shaft and having said inner diameter that is spaced by a gap .DELTA.g from said shaft;wherein .DELTA.g>x;wherein said shaft has a diameter d; andwherein said thrust pivot bearing satisfies the relationship 10d>r>1.5*(d/2).