‘Efficient Dynamics’ is the declared goal of the BMW Group’s drive train development division. “This resolves the apparent conflict between reducing consumption and emissions on the one hand and enhancing performance and agility on the other,” commented Professor Burkhard Göschel at the Vienna Motor Symposium. It means that the requirements for environmental compatibility and consumption are not viewed in isolation but in the context of the close interplay between statutory requirements, social acceptance and customer demands.
Intelligent ongoing development of drive technology
“An important component in developing drive technology lies in intelligent electric power for the drive, for example through an ‘active gear’, combined with high-performance capacitors. Developing a hybrid vehicle that drives for long distances on electric power is not commercially viable over the long term and is therefore not goal-oriented. Not everything that is technically feasible is also economical and ecological. And, most importantly, it doesn’t necessarily convince the customer. An intelligent drive where power can be called up at any time and which provides more spontaneity for less consumption is a realistic development proposition,” said Professor Göschel.
Option for the future: ‘Efficient Dynamics’ with electrified drive train
BMW says it has already played through an extreme initiative. An electric motor integrated into a BMW X5 experimental vehicle between the internal combustion engine and the gearbox supports the conventional drive during acceleration. The research vehicle was launched in 2003 and produced responses that had never been attained before, while also increasing torque to 1000 Nm in the lower range. On the other hand, the vehicle also reduced consumption by up to 15 percent in the driving cycle, the company claims.
Looking to the future, Professor Göschel can imagine a compact ‘active gear’ that integrates the electric motor and the power electronics in a single assembly within the gearbox. This will significantly reduce the additional weight and the construction space required for the system. High-power capacitors, elegantly stowed in the door sill, could contribute to an additional benefit. By comparison with battery systems, capacitors have significantly higher charge and discharge rates over the short term. As Professor Göschel sees it, the function of an intelligently honed drive is to intervene electrically in the drive train and optimize driving situations like stop-and-go traffic or acceleration.
Long-term development potential is with the internal combustion engine
However, all concepts geared towards intelligent electrification remain no more than an auxiliary solution for the internal combustion engine. BMW has significantly reduced consumption and emissions in diesel engines during recent years, while simultaneously increasing performance and torque. Valvetronic, the fully variable valve control system, has allowed BMW to achieve comparable improvements in the petrol engine. In future, the introduction of spray-guided direct injection and the implementation of lean combustion will bring consumption in the petrol engine closer to values attained by modern diesel units.
Over the long term, hydrogen is still reckoned to be the fuel with the greatest potential for safeguarding mobility in the future. BMW specialists are working on the hydrogen combustion engine, where an overall efficiency of up to 50 percent is conceivable in the long run.