The double roller full toroidal variator: A promising solution for KERS technology

We have analyzed in terms of efficiency and traction capabilities a recently patented toroidal traction drive variator: the so-called double roller full toroidal variator (DFTV). We compare its performance with the single roller fulltoroidal variator (SFTV) and the single roller half-toroidal variator (SHTV). Interestingly, the DFTV shows an improvement of the mechanical efficiency over a wide range of transmission ratios, and in particular at the unit speed ratio as in such conditions the DFTV allows for zero-spin, thus strongly enhancing its traction capabilities. The very high mechanical efficiency and superlative traction performance of the DFTV have been exploited to investigate the performance of a flywheel based Kinetic Energy Recovery Systems (KERS) where the efficiency of the variator plays an important role in determining the overall energy recovery performance. The energy boost capabilities and the overall round trip efficiency have been calculated for every type of mechanical drive and a comparison has been discussed. The results suggest that SHTV and DFTV are the best choices to improve the energy recovery potential of the mechanical KERS. © Springer-Verlag 2013