Yolga, M. and Bachinger, M., "Novel Shift Control without Clutch Slip in Hybrid Transmissions," SAE Technical Paper 2017-01-1110, 2017, doi:10.4271/2017-01-1110.
With the introduction of new regulations on emissions, fuel efficiency, driving cycles, etc. challenges for the powertrains are significantly increasing. In order to fulfil these regulations, hybrid-electric powertrains are an unquestioned option for short and long-term solutions. Hybridization however, is not only fulfilling these challenging efficiency or emission targets, but also allows numerous new possibilities on control strategies of different powertrain elements as well as new approaches of designing them. A good example is transmissions where, hybridization allows a new transmission type called Dedicated Hybrid Transmission (DHT), which enables to use novel control strategies bringing improved performance, driveability, durability and NVH behavior.This paper focuses on the novel shift strategy where friction clutches do not have to slip. The strategy introduces a novel shifting control using the integrated electric motor and special power flow of the dedicated hybrid transmissions. The novel shift strategy significantly improves shift comfort, thermal losses and element durability. In addition, several design aspects are challenged by proposing questions like selection of dog clutches over friction clutches, usage of eCVT modes in DHT and how a DHT shall be designed,.