Dynamic Bearing Device

Abstract

Disclosed is a dynamic bearing device which allows production of a smaller housing at low cost and which suppresses ion elution from the resin portion to thereby maintain cleanliness in the dynamic bearing device and exert a desired bearing performance. A dynamic bearing device 1 is equipped with a bearing sleeve 8 fixed to the inner periphery of the housing 7 , and a rotary member rotatable relative to the bearing sleeve 8 and the housing 7 , in which the rotary member is supported in the radial direction and the thrust direction in a non-contact manner by a dynamic pressure action of a lubricant fluid generated in a bearing clearance. The housing 7 is formed by injection molding of a resin composition containing polyphenylene sulfide (PPS) as the base resin and PAN type carbon fibers as a filler.

1 . A housing for a dynamic bearing device which accommodates a bearing sleeve forming a radial bearing clearance with an outer peripheral surface of a shaft portion,
 wherein the housing is formed of a resin composition containing polyphenylene sulfide (PPS) as a base resin.   
   
   
       2 . A housing for a dynamic bearing device according to  claim 1 , wherein the resin composition contains carbon fibers. 
   
   
       3 . A housing for a dynamic bearing device according to  claim 2 , wherein the carbon fibers have a tensile strength of 3000 MPa or more. 
   
   
       4 . A housing for a dynamic bearing device according to  claim 2 , wherein the carbon fibers are PAN type carbon fibers. 
   
   
       5 . A housing for a dynamic bearing device according to  claim 2 , wherein the carbon fibers have an aspect ratio of 6.5 or more. 
   
   
       6 . A housing for a dynamic bearing device according to  claim 2 , wherein the carbon fibers are contained in the resin composition in an amount of 10 to 35 vol %. 
   
   
       7 . A housing for a dynamic bearing device according to  claim 1 , wherein the resin composition contains Na ions in an amount of 2000 ppm or less. 
   
   
       8 . A housing for a dynamic bearing device according to  claim 7 , wherein the polyphenylene sulfide (PPS) is of a linear type. 
   
   
       9 . A dynamic bearing device comprising: the housing for a dynamic bearing device according to  claim 1 ; a bearing sleeve; and a shaft portion. 
   
   
       10 . A motor comprising: the dynamic bearing device according to  claim 9 ; a rotor magnet; and a stator coil generating a magnetic force between the stator coil and the rotor magnet. 
   
   
       11 . A dynamic bearing device comprising: a housing having an integral or separate bottom portion; a bearing sleeve fixed to an inner periphery of the housing; and a rotary member rotatable relative to the bearing sleeve and the housing, the rotary member being supported in a radial direction and a thrust direction in a non-contact manner by a dynamic pressure action of a lubricant fluid generated in a bearing clearance,
 wherein the lubricant fluid is an ester type lubricating oil, and wherein the housing is formed of a resin material containing as a base one of the following materials: polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polyamide (PA), thermoplastic polyimide (TPI), and polybutylene terephthalate (PBT).   
   
   
       12 . A dynamic bearing device according to  claim 11 , wherein at least one of carbon fibers and inorganic fibers are mixed with the resin material forming the housing, as a filler, and wherein the total amount of the filler is 15 to 50 wt %. 
   
   
       13 . A dynamic bearing device according to  claim 12 , wherein the filler contains 1 wt % or more of carbon fibers. 
   
   
       14 . A dynamic bearing device according to  claim 12 , wherein the inorganic fibers contain no silicon (Si). 
   
   
       15 . A dynamic bearing device according to  claim 12 , wherein the inorganic fibers are whiskers. 
   
   
       16 . A dynamic bearing device according to  claim 12 , wherein a powder conductifying agent is mixed with the filler. 
   
   
       17 . A dynamic bearing device according to  claim 16 , wherein the powder conductifying agent is 2 to 10 wt % of carbon black. 
   
   
       18 . A dynamic bearing device according to  claim 12 , wherein the upper limit of the total amount of the filler is 35 wt %.