KBE+ was contacted by a Tier 1 supplier to a major automotive OEM and was asked to develop a new and unique mechanical passive traction aiding differential. They also wanted us to develop a novel solution to the zero torque problem. For those not familiar with mechanical passive traction aiding differential technology, when there is no (or near zero) torque on the drive axle, the torque bias is infinite. The problem with this of course is that as soon as torque is applied (whether from the driveline or as the driveline transits from drive to coast or vise-versa) all the energy goes to the one drive tire with the infinite torque bias. When that happens, that tire is over-powered and spins, which unsettles the vehicle only momentarily until the differential reacts but enough to cause the vehicle to twitch at the exact instant the driver doesn’t want it to. The common solution is to use a pre-load bias on one of the drive axles and thereby offset the phenomenon for the zero torque point. Unfortunately, this creates a torque bias offset throughout the entire driveline power band, which causes the vehicle to respond differently in right-hand corners versus left-hand corners, etc.
Our solution was to incorporate progressive feedback from a cam-driven symmetric response side-gear loading system. This feature became the basis for many of the claims in the final patent, along with the ability to modify the cam geometry to tailor differential response as a function of the required vehicle dynamics. After the base design concept and several variation of prototypes were completed, KBE+ engineers supported our client’s patent writing and legal defense as the concept went through the patent application and award process. We have also supported our client as we have collaboratively extended the design applicability and feature / functions.