The basic aim of DHT technology for cost-effective PHEVs is to permit the design of very compact automatic transmissions with an integrated high-voltage electric motor on the output side of the transmission. The Vitesco Technologies cost-effective PHEV prototype offers the driver the same standard of comfortable driving and shifting that until now has been associated with plug-in hybrids equipped with a conventional 6-speed automatic transmission. And yet a DHT transmission with Vitesco technology has only four mechanical gears and has no mechanical synchromesh systems, auxiliary hydraulics or start clutch. Moving off (in 1st and 2nd gear) and reversing are handled by the electric drive motor, while synchronization is performed by a starter-alternator that also provides fast and smooth starting of the internal combustion engine.
The reassignment of functions makes it possible to reduce the number of mechanical components in the transmission, which also saves space, weight and costs. 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 electric drive, for example, DHT technology clears the way for affordable, economical and comfortable vehicles capable of performing a wide range of daily trips in all-electric mode, with zero local 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.
This new PHEV solution draws on Vitesco Technologies’ wide-ranging systems expertise in terms of overall powertrain design, and comprehensive knowledge of electric drive technology. By way of example, 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.