Keynote Presentations

How the changing demands further increase CVT's significance CVT offering a flexible base for a variety of solutions   Martin Krüßmann Vice President Engineering – Bosch Transmission Technology B.V.

Abstract — One can not say that an idea that originated over 500 years ago is new. But Leonardo daVinci’s ideal of a stepless transmission still shows so much further potential that it is far from settled technology. Looking at the current automotive transmission world, CVT’s fuel economy for new applications mostly outperforms the MT option. Next generations of gasoline and diesel engines will strongly benefit from the CVT’s free ratio strategy. At the same time further steps in efficiency as well on pushbelt variator, as on system level keep on being introduced. Increasing power density enables smaller packaging and with this lower weight and cost.

These improvements directly compete hybrid solutions on the fuel to cost balance. And at the same time CVT’s are a perfect match in hybrid powertrains for their flexible ratio control and can exploit extra potential in such configurations.

Modelling belt and chain CVT's: Traction, slip, and shift performance   Giuseppe Carbone Professor of Applied Mechanics, Politecnico di Bari

Abstract - The automotive market requires high performance cars in terms of comfort, drivability, fuel saving and reduced polluting emissions. The continuously variable transmission (CVT) represents one of the most promising solution to optimize the thermal engine working conditions, get the highest efficiency, and, therefore, improve fuel saving and reduce greenhouse gasses emissions. To achieve these objectives understanding the CVT dynamics is crucial, and developing computationally light CVT models plays a key role under the perspective of control purposes. Indeed the availability of simple and computationally light but accurate CVT models may be exploited by control designers to develop advanced strategies that allow the CVT to operate close to the highest efficiency point.

The critical ingredients that must be considered to develop accurate CVT models will be discussed, as well as different modelling approaches (e.g. multibody or continuum models). The theoretically predicted performance of CVT in terms of traction, slip and shift capabilities will be, then, critically compared with experimental data.

New CVT: Lightweight, Small, Wide ratio coverage and Low Friction   Toshimasa Doi Chief Technology Officer, Jatco Ltd.

Abstract — To accomplish good fuel economy, it is important to minimize any friction.  But in the real world, to get wide ratio coverage for the transmission it is also important to let the engine operate in good operating point. As there is a limitation for the pulley size, it is difficult to get wide ratio coverage.

After investigating many concepts to get wide ratio coverage, Jatco decided to use auxiliary transmission. We describe the key technologies to get light weighted, small, wide ratio coverage and low friction new CVT which we introduced to the Japanese market summer 2009. We also describe the reason why CVT can show the good fuel economy in the real world.