Applications of Automatic Control to Pressurized Oil Film Bearings

Abstract

Expressions for the load-carrying capacity, stiffness and damping rate of pressurized oil film bearings are derived and expressed in terms of the variables available to the designer By adding a simple automatic flow valve, operated by pressure feed-back, the pressurized oil film exhibits infinite stiffness to steady normal loads. The method can be adapted for a system, embodying pilot pad control of a main bearing pad, in which the pilot pad slides on a flat strip and the film thickness of the main pad is varied to compensate for undulations in the main slideway A further experimental and theoretical investigation is described in which feed-back control is used to support concentrically the shaft of a journal bearing. With a shaft diameter of 2 in. and a radial clearance of 0002 in. the eccentricity is generally not greater than 2 × 10-5 in., as inferred from the pressure measurements, for loads exceeding 300 lb and rotational speeds up to 1200 rev/min. It is argued that much greater loads and higher rotational speeds can be attained with virtually no eccentricity