Frictional Power Loss Distribution of Automotive Axles- Experimental Evaluation and Analysis

With more stringent emission and Co2 norms (e.g. CAFÉ, RDE), it has become extremely important for all OEMs to push their boundary and make vehicle & powertrain more and more efficient. Frictional power loss of automotive axles is major source of losses which reduce the vehicle fuel economy and increase Co2 emissions. To make axles with low frictional power loss consumption, it is first important to understand the distribution of the frictional power i.e. where the energy goes and how it is distributed in the subcomponents of axles. This paper presents the main area of frictional power loss distribution inside an automotive axle of passenger car. For experimental evaluation one frictional torque measurement test rig was prepared and axle power loss was measured by stripping down one by one component to understand the distribution of frictional losses. For this study two different size of axles were compared to understand the impact of bearing size and gear size on power loss characteristics. It was observed that majority of total frictional power loss in an axle contributed by pinion head-tail bearing and its seals (~50 %), second highest contribution total power loss is contributed by pinion-ring gear pair and differential bearings and remaining by wheel end bearing and seals. With this study the frictional loss distribution of axle was quantified & major area of improvement was identified, and future actions plans were taken to improve the axles.