Mahle has developed a new, fully integrated and modular plug-in hybrid drive for vehicles from the B-segment to large SUVs from the J-segment. The core is a “bimodal hybrid arrangement” that allows both parallel and serial operation.
The engineers wanted to combine the advantages of a serial and parallel hybrid for the Mahle Modular Hybrid Powertrain (MMHP) and have therefore developed the bimodal architecture. With a high battery charge, the vehicle can be propelled by electric drive alone, whereas with a low charge and low driving speeds it can switch to serial hybrid mode. At higher speeds, direct drive by the combustion engine is possible.
According to Mahle, the performance of the electric drive train used in the MMHP reduces the requirements placed on the combustion engine, so a special engine could be developed for this application. The “Dedicated Hybrid Engine” (DHE) is intended above all to be less expensive. Depending on the size of the vehicle, this is a turbo gasoline engine developed by Mahle with two or three cylinders. Since the combustion engine rarely drives the wheels directly, it could be optimized for other ranges and thus manages with cost-effective features such as intake manifold injection, a single overhead camshaft without variable valve control and simple two-valve technology.
Even in the first test phase, the drive had already achieved a specific fuel consumption of 207 grams per kilowatt hour, and in future even up to 195 grams would be possible in lean operation. Mahle has calculated that a compact SUV according to the WLTP standard would produce CO2 emissions of 18 grams per kilometer. The DHE engine should weigh just as much as a current four-cylinder petrol engine with six-speed manual transmission.
“The further development of hybrid technology is crucial for the entire industry in order to achieve future emission targets,” says Martin Berger, Head of Mahle Powertrain, Mahle’s Engineering Services business unit. “As a result of the focus on reduced emissions and strict schedules, new vehicle and technology development must occur within a much tighter timeframe.”
Depending on the application, the MMHP is equipped with a 1-, 2- or 4-gear transmission – in a small car with a rigid transmission, while a large SUV gets the four gears.