Diamond like-carbon coatings for electric vehicle transmission efficiency

A barrier to the adoption of battery electric vehicles is consumer range anxiety. This paper investigates the driving range conceded as a result of the parasitic frictional losses incurred at the gear mesh in a two-stage battery electric vehicle transmission. Amelioration of the parasitic losses through changes to surface roughness and application of thin wear resistant coatings such as DLC are considered. The tribo-dynamics model of the gear frictional losses includes topographical structure of the respective surfaces characterised through surface specific fractal parameters. Analysis shows that the use of the investigated amorphous hydrogenated undoped DLC coating could potentially save 1.1 km of vehicle range during extra urban driving and 0.9 km under urban driving over a full battery discharge cycle.