Vitesco Technologies, the Powertrain business area of Continental, have presented a Dedicated Hybrid Transmission, or DHT, at the CTI Symposium in Berlin.
The Vitesco DHT is the first time an extremely cost-effective and compact hybrid transmission solution with integrated electric machines has been introduced. With its mix of electric power and gears, it is meant for hybrid uses, such as in plug-in hybrid electric vehicles (PHEVs).
Vitesco Technologies are using their considerable know-how in the field of powertrain electrification to pave the way for genuinely affordable hybrid vehicles. The task is all the more challenging because a hybrid has two power sources – an internal combustion engine and an electric motor, complete with power electronics and a high-voltage battery. This additional technical infrastructure can raise the cost of an all-electric-capable high-voltage hybrid to a level that prohibits significant market penetration. Yet, if the costs could somehow be kept in check, hybrid vehicles, many of which are capable of an electric driving range of 50 km or more, could potentially play a significant part in reducing exhaust emissions from everyday driving.
The Vitesco Technologies DHT is one unique solution. At the heart is the expanded role played by the electric motor which is no longer simply a means of propulsion and energy recuperation. The DHT technology for cost-effective PHEVs permitted the design of very compact automatic transmissions with an integrated high-voltage electric motor on the output side of the transmission.
The prototype offers the driver the same standard of driving and shifting thus far associated with plug-in hybrids equipped with a conventional automatic transmission. However, the DHT has only four mechanical gears and has no mechanical synchromesh systems, auxiliary hydraulics or start clutch. Moving off in first and second, and reversing, are handled by the electric motor, while synchronization is performed by a starter-alternator that also provides fast and smooth starting of the internal combustion engine. This reassignment of functions makes it possible to reduce the number of mechanical components in the transmission saving space, weight and cost. The smooth, quiet shifting offered by the DHT despite its simple dog-clutch design is entirely down to the high dynamic capability of the electric motor functions, which in turn requires a profound understanding of the relevant control technology. DHT technology for low-cost PHEVs marks a further step in Vitesco Technologies’ systematic electrification strategy.
This makes the DHT a natural choice for front transverse mounting in compact segment vehicles, where installation space is always a challenge. Combined with a low-cost port-injection gasoline engine and all-electric-capable drive with zero emissions. The DHT for cost-effective PHEVs is designed for speeds of up to 120 km/h in all-electric mode, and up to 160 km/h in hybrid mode.
Stephan Rebhan, Head of Technology and Innovation at Vitesco Technologies, said, “So far it has not been possible to tap the full potential of plug-in hybrids and full hybrids for reducing CO2 emissions because the expensive powertrain of these vehicles puts them out of reach for many customers. We have identified further potential here which our DHT technology for cost-effective PHEVs is designed to leverage. With a view to cutting CO2 emissions, PHEVs are a form of electric mobility which deserves to become much more successful in the future.
“To ensure compliance with future EU CO2 emissions limits, it will be particularly important to get a grip on costs, which currently act as a barrier to the wider market success of hybrid electric powertrains,” concluded Rebhan.
Also Read: Plug-in Hybrids and Future Propulsion
