Patent ID: 8742638

Claim:
A hydrodynamic bearing assembly, comprising: a sleeve including a shaft hole formed therein; and a shaft rotatably inserted into the shaft hole, the shaft constituting, together with the sleeve, a bearing clearance filled with lubricating fluid, wherein at least one of an inner circumferential surface of the sleeve and an outer circumferential surface of the shaft includes upper and lower radial dynamic pressure grooves having a herringbone pattern formed therein so as to pump the lubricating fluid filled in the bearing clearance, and when an axial direction distance from an upper end of the upper radial dynamic pressure groove to a highest pressure portion is ‘a’, an axial direction distance from a lower end of the upper radial dynamic pressure groove to the highest pressure portion is ‘b’, an axial direction distance from an upper end of the lower radial dynamic pressure groove to a highest pressure portion is ‘c’, and an axial direction distance from a lower end of the lower radial dynamic pressure groove to the highest pressure portion is ‘d’, conditional expressions a+b>c+d and b−a>c−d>0 are satisfied.