Split‐Path Transmissions

Abstract

The topic of split‐path transmissions, by whatever name, has been well established in some mobile vehicle sectors and has more recently spread into the automobile and light vehicle segments. This chapter describes the concepts and potential advantages of using a continuously variable transmission system with more than one path between input and output. The basic concept is introduced and the simplest configurations to split the power flow are discussed. There is a detailed review of the analysis of the simple epicyclic gear in the form that is most amenable for split‐path analysis. This leads into an analysis and presentation of the main characteristics of split‐path transmissions using a single epicyclic gear. The most advantageous regions of operation are identified and representative implementations in the automobile sector using different variators are described. Attention is drawn to possible component speed and torque limits and the inclusion of some allowance for variator efficiency. The extension of the technique to the use of more than one epicyclic gear is introduced, and the difference in characteristics from a single epicyclic is identified. Reference is made to some implementations of these configurations, including multimode systems.