Hydrodynamic bearing, hydrodynamic bearing apparatus, fabrication method of hydrodynamic bearing and bearing surface working method

Abstract

A problem of the invention resides in that in a hydrodynamic bearing apparatus for rotatably supporting a rotor by a hydrodynamic bearing, wear of the apparatus caused by sliding contact of dynamic pressure bearing faces in starting and stopping thereof is prevented to thereby promote durability, working of a dynamic pressure generating groove is facilitated and the bearing faces are prevented from being adsorbed to each other. As resolving means therefor, by providing a low friction metal layer C having water repellency at dynamic pressure bearing portions 3 a and 3 b of a hydrodynamic bearing apparatus 1, friction can be reduced, wear or dust formation can effectively be restrained and the bearing faces can be prevented from being adsorbed to each other by dew condensation.

What is claimed is:  
     
         1 . A hydrodynamic bearing comprising: 
 a fixing member fixed to a side of a stator;    a rotating member fixed to a side of a rotor capable of rotating relative to the stator and opposed to the fixing member via a fluid; and    hydrodynamic pressure generating means for generating a dynamic pressure by the fluid between the rotating member and the fixing member in rotating the rotor;    wherein in at least one of the rotating member and the fixing member, a surface thereof opposed to other thereof is a low friction metal layer having water repellency.    
     
     
         2 . The hydrodynamic bearing according to claim  1 : 
 wherein the low friction metal layer having the water repellency is constituted by dispersing very small particles realizing the water repellency and low friction performance in a metal base.    
     
     
         3 . The hydrodynamic bearing according to claim  2 : 
 wherein the very small particles are very small particles of a fluorine compound.    
     
     
         4 . The hydrodynamic bearing according to claim  1 : 
 wherein a hardness of the low friction metal layer falls in a range of Hv of 600 through 1000 and a friction coefficient thereof is equal to or smaller than 0.25.    
     
     
         5 . A hydrodynamic bearing apparatus comprising: 
 a stator;    a rotor rotated relative to the stator; and    the hydrodynamic bearing according to any one of claims  1  through  4 .    
     
     
         6 . A method of fabricating a hydrodynamic bearing comprising: 
 a plating step of forming a low friction metal layer having water repellency constituted by dispersing very small particles realizing the water repellency and low friction performance in a metal base of composite plating including at least one of phosphor and boron in at least one of base members of a rotating member and a fixing member on a face thereof opposed to other thereof by an electroless plating;    a hardening treatment step of hardening the low friction metal layer by heating the one base member at predetermined hardening heat treatment temperature after the plating step;    a stress relieving step for relieving stress of the base member by heating at temperature equal to or higher than the hardening heat treatment temperature of the hardening treatment prior to the plating treatment; and    an integrating step of integrating the one and the other in a state in which the low friction metal layer of the one is opposed to the other and a hydrodynamic pressure can be generated between the one and the other.    
     
     
         7 . A method of working a surface of a bearing for providing a low friction metal layer having water repellency on the surface of the bearing of a hydrodynamic bearing rotatably supporting a rotor, said method comprising: 
 an electroless plating step of forming the low friction metal layer including very small particles realizing the water repellency and low friction performance by an electroless plating on the surface of the bearing of the hydrodynamic bearing; and    a hardening heat treatment step of hardening the low friction metal layer by setting hardening heat treatment temperature to be equal to and higher than 200° C. and equal to and lower than 400° C.