DYNAMIC PRESSURE BEARING AND SPINDLE MOTOR WITH THE BEARING

摘要

A dynamic pressure bearing small in size and weight, simple in structure, and low in cost but capable of providing a sufficient rigidity, comprising a radial bearing part having grooves (26) to which fluid such as air can be led, and a thrust bearing part of which one end communicates with the radial bearing part and of which other end communicates with the outside, wherein the fluid led to the radial bearing part is led further into the thrust bearing part and, using a pressure of the fluid, a stable thrust force can be obtained without separately providing a thrust dynamic pressure generating mechanism, the surface area of the grooves (26) should be 40% or less of the entire surface area of the radial bearing part and the number of grooves (26) should desirably be six or less and, by making the grooves (26) in asymmetrical shape deeper at upstream part of air flow and shallower at downstream part thereof, the rigidity of the radial bearing part and the thrust bearing part can be increased.