Hydrodynamic type oil-impregnated sintered bearing

A spindle motor for information equipment comprising:

• a rotating shaft rotating with rotating components of the information equipment;
• a bearing for supporting the rotating shaft;
• and
• a rotor and stator arranged to face each other via a prescribed gap,
• wherein said bearing comprises a porous bearing body of sintered metal having a bearing surface opposed to a sliding surface of the rotating shaft via a bearing clearance, and hydrodynamic pressure generating grooves slating against an axial direction provided in the bearing surface, and a lubricant impregnated in pores inside said bearing body,
• wherein said lubricant is a lubricating grease comprising a thickener in a compounding ratio of from 0.1% to 5.0% by weight,
• wherein the rate of area of surface holes of the bearing surface is set within a range of 3%-15%,
• wherein a base oil of said lubricating grease forms a lubricating film in the bearing clearance due to the hydrodynamic pressure generating grooves while circulating between the inside of the bearing body and the bearing clearance through the surface holes of the bearing surface, so that the lubricating Elm continuously non-contact supports the rotating shaft, and
• wherein the thickener of said lubricating grease is more than one type of urea compound selected from the group represented by the following formula (1):
• R1-NHCONH—R2-NHCONII—R3, (1)
• wherein R2 represents an aromatic hydrocarbon group having from 6 to 15 carbon atoms, R1 and R3 represent an aromatic hydrocarbon group having from 6 to 12 carbon atoms or an alkyl group having from 8 to 20 carbon atoms, and the rates of the aromatic hydrocarbon group in RI and 123 range from 0% to 100% by mole.