In rotary-vane type vacuum pumps, the friction torque which is generated between vane-tips and sliding surface of the stator is so large, that it increases considerably at high speed operation. The recent advance in speed up of the pump has posed an important problem of reducing the friction loss at vane-tips to lower its driving torque.
Some of the results of studies made on the reduction in friction torque at vane-tips are presented in this paper as follows.
(1) Applying the Reynolds equation on a viscous lubrication of a slide bearing to vane-tips, effects of various radii of curvature at vane-tips were studied.
(2) Effects of various viscosities of lubricant were studied by the same method as (1).
(3) In terms of a swing motion of vanes, the range of choice for the radius of curvature at vane-tips was examined.