Feasibility Study of Ball Ramp Wear using Dynamic Simulation

<div class="section abstract"><div class="htmlview paragraph">In the electric limited slip differential (eLSD) of an All-Wheel-Drive system, the ball ramp provides a major role in the facilitation of power flow by cam motion. When an electromechanical motor rotates the gear-attached drive plate in the ball ramp, the ball is inclined along the ramp’s geometry and resultantly pushes the static plate upside. This axial movement causes the engagement and disengagement of the clutch pack located on the upper side of the ball ramp. Therefore, depending on the ramp’s geometry, the performance of the ball ramp is maintained. In regards to our test research, ball ramp is weaker for wear than the fatigue failure, which is commonly occurred to rolling behavior. The load associated with the repeated oscillations is what specifically causes wear on the ramp. When the wear occurs, the ball position becomes offset on the wear region, which causes a change in motion during clutch engagement and can therefore affect the overall input torque. This study focuses on such wear and load relationships. To address potential wear magnitudes, ball forces from dynamic simulation modeling are applied to the wear equation. After deriving the relationship between ball-load and wear, design of experiment for geometric tolerance measurements through dynamic simulation is conducted to define wear feasibilities per individual design parameter. Pitch circle diameters, ramp radii, and ramp height tolerances are reviewed in this study and derived for the sensitivity analysis of each design factor.</div></div>