Analytical and Numerical Approach on Design of Cageless Open Differential Unit

Abstract

A differential is a gear train that transmits an engine’s torque to the wheels. During a turn, the outer and inner wheels of the vehicle are forced to travel along paths of different radii. A differential allows the outer driving wheel to rotate at a faster speed when compared to the inner driving wheel during a turn. It is designed such that, increase in speed of one wheel is balanced by a decrease in speed of the other. This ensures that the vehicle can negotiate a turning without slipping. The gears in the differential are supported by a cage which results in its bulky appearance and heavy form. This causes a number of disadvantages such as difference in length of the driveshafts and offset center of mass of the system due to asymmetrical design. Such a cage also adds additional weight to the vehicle and increases fuel consumption as a consequence. Its elimination results in a more compact and lightweight configuration. This paper focuses on the complete methodology of designing and analyzing a cageless differential. Various materials were considered for the assembly and one with adequate properties of strength, wear resistance and other core parameters was selected. Gear ratios were obtained through theoretical calculation and the values were used as input for designing using Solidworks software. Finite element analysis of the gear train was carried out using ANSYS Workbench to test the structural integrity and durability of the system through various types of analysis such as linear static structural, fatigue and explicit dynamic analysis. The results proved that the design meets the desired functionality and is an improvement to the conventional type of differential gearbox.