End-thrust design for parallel-axis differential

Abstract

Frictional resistance, resulting from end thrust developed by planetary gearing, is appreciably increased to improve control over torque bias characteristics in parallel-axis/torque-proportioning automotive differentials using an unusual planetary combination gear having a first toothed portion which meshes with one of the differential's sun/side gears and a second toothed portion which meshes with a paired combination gear, these first and second toothed portions being separated by a non-meshing portion that 'straddles' (i.e., that provides clearance for avoiding contact with) the sun gear that is in mesh with its paired combination gear. In the most preferred embodiments, the second toothed portion of each combination gear is divided into two separate and distinct meshing areas located, respectively, at the gear's outer axial ends. The end faces of the combination gears are used as frictional surfaces for controlling the torque bias of the differential assembly, and a significant measure of control over torque bias is provided by the appropriate selection of the angle and hand of the helically-toothed meshing portions of the sun and planetary combination gears, such tooth designs being selected so that the axial-thrust forces created on the combination gears result in additional frictional resistance.