Four engine manufacturers are currently participating in Formula 1, supplying a V6 hybrid with an electrically-assisted turbocharger. Which of these four will be the first to market this e-turbo on one of their production vehicles? Probably Mercedes-AMG, which has just announced that its next model will be equipped with this type of system, supplied by Garrett Motion.
The electrically-assisted turbocharger has been equipping Formula 1 cars since the introduction of new regulations in 2014, enforcing a competition for power through increased efficiency. This turbocharger recovers some of the energy lost in the exhaust by the turbine driving the motor-generator (MGU-H), by using the electricity generated to charge a battery or, alternatively, powering an electric motor (MGU-K) connected to the crankshaft. Energy is also recovered from the inertia of the turbomachine when the accelerator is released (see our tech focus article "Our engine achieves an efficiency of between 50 and 55%, Rémi Taffin, Renault F1"). The presence of the MGU-H also makes it possible to reduce the response time between demand and torque production or to provide high boost pressure at low engine speeds.
Several development projects are under way for heavy-duty engines, which have the advantage of operating for long periods under heavy load, which is not the case for passenger cars. Mercedes- AMG has just announced that its engine designers are in the final stages of developing an engine using an e-turbo, in collaboration with Garrett Motion. According to the manufacturer: "This technology, obtained directly from Formula 1, resolves the argument of choosing between a small turbocharger with a fast response time but relatively low maximum performance and a large turbocharger with high performance, but which however may suffer from a relatively long response time. “
The turbocharger has a 4 cm wide motor-generator placed between the bearings of the shaft connecting the turbine to the compressor. It can reach 170,000 rpm and is supplied with 48 V via power electronics directly attached to the crankcase, next to the electromechanical relief valve.
Mercedes-AMG adds that e-turbo not only increases torque at very low revs, but also maintains a certain level of supercharging when the intake throttle is closed so that the engine can deliver torque as soon as the accelerator is actioned.
According to Tobias Moers, Chairman of the Board of Mercedes-AMG GmbH, the use of an e-turbo is a further example of the manufacturer's commitment to electrified solutions. He explains: "With this approach, we are strategically complementing our modular technology and adapting it to our performance requirements. Initially, this includes the electrified turbocharger - an example of the transfer of Formula 1 technology to everyday road use, a product with which we will take turbocharged combustion engines to a previously unattainable level of agility," evoking especially 48 V hybridization or high-voltage plug-in hybrids.
The press release shows the e-turbo on an engine that appears to be a 4-cylinder, so it's probably an evolution of the M139 2.0-litre that powers the Mercedes-AMG A 45 S and CLA 45 S, the subject of our next Focus tech.
Other advantages are expected from e-turbo, including improved combustion chamber scavenging to limit the risk of knocking, reduced CO2 emissions or easier adaptation to RDE under the Euro 7 standard. How e-turbo works, its advantages, limitations, and current projects will be presented in a forthcoming dossier.