New Diesel Mild-Hybrid Powertrain
2 October 2004
Three leading European manufacturers (two powertrain, one electric motor) have been collaborating on a new diesel mild-hybrid powertrain, called the ECO-TARGET. The partners—AVL, GETRAG and ATB Antriebssysteme Thien—showed a prototype vehicle fitted with the system at the recent 16th Engine & Environment Conference in Austria.
A mild hybrid design uses the electric motor to contribute to propulsion, as well as running the electronic systems, supporting stop-start, and other fuel-saving measures, but not as a sole source of motive power. (A Short Field Guide to Hybrids.)
The ECO-Target consists of a 60 kW (80 hp) 1.2-liter diesel engine matched with a 6-speed transmission and a 10kW (13 hp), 42V electric motor fitted to the gearbox. AVL provided the engine and the overall electronic management, GETRAG the transmission, and ATB the electric motor.
Their design goal was to reduce CO2 emissions to approximately 90–100 g/km, while matching the comfort and engine response of a baseline 2-liter diesel powertrain. (The Kyoto protocol stipulates fleet CO2 emissions of 90 g/km by 2010.)
The resulting ECO-TARGET (system package upper right, architecture bottom right) is compact and designed to enable an “add-on” hybrid system for conventional powertrains. Some highlights of the system design:
Cooling of the power electronics and the electric motor is via the engine’s cooling circuit.
The electric motor is connected to the transmission via an intermediate gearbox and can be operated as a starter, generator or motor.
Electrical launch assistance and boosting (the electric motor contributes to the propulsion of the vehicle, but never is the sole source as in a full hybrid).
Engine stop-start and regenerative braking.
Use of a super-capacitor instead of 42V battery.
AVL claims a 30% improvement in fuel economy and reduced emissions against the baseline conventional 2-liter diesel.
I’m trying to get more information about the prototype shown earlier last month, more performance data, some sense of the manufacturing economics and any possible automaker partners. It seems to me, though, that a packaged system approach like this should make a more rapid rollout of mild-hybrid diesels possible.
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