Limited slip differential
AssigneeEaton Corporation
InventorDavid W. L. Barnett
Life of this patent
Estimating the term…
Abstract
In order to provide pulsating thrust on vehicle half-shafts during excess differential actions such as occur on spin-outs or skids on ice, the side gear teeth are modified to exhibit two different e.g. involutes on the single tooth engagement zone (P.sub.1 -P.sub.2). Their junction line is a convex discontinuity (Q), the modified teeth becoming thicker. The pinions are typically unmodified. The pulsating increases friction, which reduces spin-out tendencies. The friction can be increased more by inserting friction rings between the side gears and their bearings.
Claims12
A limited slip differential (12) utilizing gear teeth having modified gear tooth profiles comprising;
- a housing rotatable by a prime mover;
- at least one driving pinion (22) mounted to be freely rotatable about its own axis in the housing;
- two parallel driven side gears (24) rotatably mounted in said housing by side gear bearings (29-30);
- first bevel gear teeth on the pinion for meshing with second bevel gear teeth on the side gears during differential action, a contact ratio of meshing of said first and second gear teeth during differential action selected to be between one and two;
- said differential gear tooth profile modification characterized by:
- at least one of said first and second gear teeth being modified relative to corresponding unmodified (dashed contour, FIG. 1) gear teeth by having a two-part profile comprising a first (X) and a second (Y) part defining a discontinuity line (Q) at the intersection thereof, said intersection occurring within the single-tooth meshing contact boundaries (P.sub.1, P.sub.2) of said modified tooth which boundaries substantially correspond with the single tooth meshing contact boundaries of corresponding unmodified gear teeth, the two different profile parts (X,Y) extending from the discontinuity line (Q) through the single-tooth contact boundary lines (P.sub.1, P.sub.2) and thence through the double-tooth meshing contact zones (W, Z), said first (X) and second (Y) parts of the modified gear tooth profile defining different pressure angles of mesh (.phi..sub.1, .phi..sub.2) to produce differing first and second axial thrust forces on each side gear;
- whereby
- for any speed of differencing, the first and second axial forces are different;
- and whereby
- each tooth meshing causes an axial thrust force pulsation on the side gear bearings,
- the average pressure angle of mesh of the two different profiles (eg (.phi..sub.1 +.phi..sub.2)/2 corresponding to the pressure angle of mesh of that profile which could have been chosen for a corresponding unmodified tooth to be conjugate with teeth of the other set of gear teeth.
Dependencies are inferred from the claim text.