An Evaluation of Torque Bias and Efficiency of Torsen Differential

Since 1983 the Torsen® differential has been employed in the powertrain of more than two-dozen sedans, SUVs, and military vehicles. This differential device is renowned for its unique high torque bias capacity. Torque bias has long been recognized as a desirable drivetrain characteristic that enhances both a vehicle's drivability and stability. Since the generation of torque bias relies on friction, the know-how in achieving balanced design of torque bias and efficiency is crucial. Presented in this paper is an analytical evaluation of the performance of Torsen differential with respect to these parameters. The mathematical model provides effective guidance in design optimization. The performance predictions were found to correlate well with experimentally measured data. In an effort to explore the theory behind the Torsen differential design, the general subject of speed differentiation and torque bias generation is reviewed. In this discussion, the design and function of the friction-clutch-based limited slip differential, the Torsen differential, and the lockable differential are compared, differential devices.