Patent ID: 7740407

Claim:
A hydrodynamic bearing type rotary device, comprising: a sleeve having a bearing hole, a shaft which is inserted into the bearing hole of the sleeve so as to be rotatable; a hub which is attached to one end of the shaft; a first lubricant reservoir which is formed between the hub and an end surface of the sleeve and which has a maximum gap s 1 ; a radial bearing in which radial hydrodynamic grooves are formed on at least one of an outer peripheral surface of the shaft or an inner peripheral surface of the sleeve, and which has a gap g 1 ; and a second lubricant reservoir which has a maximum gap g 2 between an outer peripheral surface of the sleeve and an inner peripheral surface of the hub, the inner peripheral surface of the hub having an inner diameter slightly larger than the outer peripheral surface of the sleeve or an inner peripheral surface of a stopper member attached to the hub, wherein: a lubricant is held in the radial bearing, the first lubricant reservoir and the second lubricant reservoir; and parameters of the gaps (Pg 1 , Ps 1 , Pg 2 ) have the relationship which satisfy the following relational expression (B): Pg1>Ps1>Pg2 (B), in which, when the lubricant reservoir has a substantially tubular shape, Pg 1 and Pg 2 are defined as follows: Fgo=π×Do ×γ×cos θ (1) Fgi=π×Di ×Γ×cos θ (2) Di=Do− 2 ×rg (3) Fg=Fgo+Fgi (4) Ag =π×( Do^ 2− Di^ 2)/4 (5) Pg=Fg/Ag (6) γ: Surface tension of lubricant [N/m] θ: Contact angle of oil [radian] Do: Outer diameter of tube [m] Di: Inner diameter of tube [m] rg: Oil film thickness of tube [m], and when the lubricant reservoir has a substantially thin disc shape, Ps 1 is defined as follows: Fs 1=2π× Ds ×γ×cos θ (7) As 1=π× Ds×S 1 (8) Ps 1= Fs 1/ As 1 (9) Ds: Inner diameter of lubricant reservoir having maximum gap S 1 [m] S 1 : Maximum gap of the lubricant reservoir between sleeve and hub [m].