| In recent years, driveline efficiency has become an important aspect of automotive design. The realized efficiency losses of a gear box are attributable to sliding and rolling frictional losses of the meshing of gear teeth, bearing and seal drag torques, churning and viscous pumping losses, lubricant properties and flow management.;This applied research focuses on the development of an optimization process for hypoid gear drive system efficiency. The process which allows the examination of complex simulation model behavior includes a variety of design variables, manufacturing processes, problem formulation, and the design, implementation, and analysis of engineered experiments.;Response surface methodology enables the development of second order models that accurately describe the responses by conducting tests of hypothesis for EPA test schedules at 0 and 4000 miles. Due to multiple responses, the desirability function approach is employed to create a balanced solution and find the optimal setting of control factors by maximizing composite desirability. All of the variables have mileage-varying effects. Hypoid gear surface finish produces the highest rate of response and is apparently the most statistically significant input variable. Low friction bearing designs, lubricant viscosity, oil fill quantity, and pinion and differential bearing preloads are design variables that have varying levels of significance and directly affect axle system efficiency. The combination of these simulation paradigms is used to illustrate a fuel efficient axle system. The cost penalties that may be avoided due to noncompliance to CAFE standards are calculated using a simulation program that predicts vehicle fuel economy performance. |
