Study of Hybrid Lubrication at the Tooth Contact of a Wormgear Transmission: Part 1—Formulation and Analysis

Abstract

The paper presents a lubrication analysis for the tooth contact of a proposed wormgear transmission. The information needed for the lubrication analysis has been mostly obtained from a previously published wormgear analysis. The information includes the geometry of the clearance between the meshing surfaces, the velocity of the worm surface relative to the gear surface, and the normal force acting on a gear tooth as it moves through the meshing zone. The lubrication analysis is carried out after a design of the oil supply configuration is made, that consists of a single transverse oil recess and a capillary tube flow restrictor. Under the predetermined normal force, the lubrication analysis is aimed at obtaining the needed supply pressure to separate the meshing surfaces by a minimum oil film thickness, which is prescribed to insure the establishment of fluid film lubrication at the contact. The lubrication analysis considers (1) the hybrid lubrication effect (combined hydrostatic action and hydrodynamic wedge and squeeze actions), (2) the temperature rise in the oil film flow and the restrictor flow, and (3) the pressure and temperature dependence of oil properties. Part I describes the formulation of the oil film flow problem (in discrete form) and the restrictor flow problem (in analytical form). The two problems are coupled through the conditions of flow continuity and energy balance in the oil recess.