| The CVT has advantages over the conventional stepped ratio transmission because of its smooth, stepless shifting, simplified design, and a potential for reduced fuel consumption and tailpipe emissions. The power split CVPST has a potentially higher mechanical efficiency than a conventional shaft-to-shaft CVT, but it is unknown whether that efficiency can be improved. For the CVPST, the branch control circuit that contains the CVT can be disengaged at the ring gear for a 1:1 overall transmission ratio, which will interrupt the power flow through the CVT. This could increase overall efficiency because the branch control circuit is no longer transmitting any power. This system is compared to a conventional CVPST, a direct-drive CVPST, and a shaft-to-shaft CVT. A computer program is produced to study the mechanical losses for each system over the entire operating range of a representative simulation model. From this analysis, the value of disengaging the branch control circuit at the ring gear can be determined. |
