D he charging with two exhaust gas turbochargers is nothing new. However, since the conventional chargers live from the energy of the exhaust gas flow, depending on the coordination, the so-called turbo hole results at very low speeds (i.e. without sufficient exhaust gas flow).
Audi wants this in the future with an electrically powered charger to grapple. This makes it possible - regardless of the available exhaust gas energy - to achieve a rapid build-up of boost pressure and high torque even at the lowest engine speeds.
In the advance development of diesel engine development at Audi in Neckarsulm, a 3.0 V6 TDI was set up and tuned as an electric biturbo . It is a combination of a conventional exhaust gas turbocharger with an additional electrically driven compressor - from the outside it can hardly be distinguished from a conventional turbocharger.
Instead of the turbine wheel driven by the exhaust gas flow, it integrates - as an additional charging stage in series with the exhaust gas turbocharger - a small electric machine that brings the compressor wheel up to very high speeds within a very short time. The electrically driven compressor is connected behind the turbocharger and the charge air cooler. In most operating states, this is bypassed by a bypass. However, when the flap integrated in the bypass closes - when the energy supply on the turbine side is low - the air is fed into the electric compressor and compressed there for the second time. The torque build-up should take place much earlier and smooth out the turbo lag. The electric charger is powered by energy that is largely obtained through recuperation in the overrun phases.
Performance data for the new charging technology and a possible series launch were not mentioned.