Atego BlueTEC Hybrid

Lots of wiring means many potential spots for errors. To ensure that such errors don’t occur, personnel went over the new bus with a fine-tooth comb after all equipment was installed.

 

The situation is somewhat different with trucks, for which parallel hybrids have proved to be the best solution in terms of cost, efficiency, reliability, and technical considerations. Like series hybrids, parallel hybrid drives consist of a combustion engine and an electric motor. Here, however, each of the drive units can be used to power the vehicle, either individually or in tandem/parallel. In the latter case, the output of the two is combined (power boost).

Despite the fact that different diesel engines are used in vehicles of different sizes and brands, the engineers at Daimler Trucks developed a common parallel hybrid drive architecture for all of their vehicles. The electric motor employed here is mounted behind the combustion engine and clutch, but in front of the transmission. This arrangement makes it possible to drive in a purely electric mode. In addition, it has proved to be the best possible method for reconciling requirements associated with manufacturing complexity, vehicle dimensions, weight, and performance.

In November 2007, the Mercedes-Benz Atego BlueTec Hybrid was launched as a 7.5 and 12-ton GVW vehicle. Tough customer testing of the 7.5-ton Atego BlueTec Hybrid began in February at Deutsche Post, where the vehicle is being used to deliver mail.

Downsizing

To compensate for the additional weight of the electric drive component, Daimler engineers downsized the hybrid Atego by utilizing a smaller diesel engine than is usually the case. The 7.5-ton version is now equipped with a light and compact four-cylinder diesel engine that generates 92 kW (125 hp) and maximum torque of 294 Nm. The engine is joined by a water-cooled electric motor with a maximum output of 35 kW and maximum torque of 200 Nm.

The electric motor primarily comes into play to assist the diesel unit at low engine speeds. When the truck reaches a steady speed after acceleration, for example, it switches to an economy mode in which it is powered solely by the diesel engine. Acceleration itself, however, is handled exclusively by the electric motor. Power is supplied to the motor by lithium-ion batteries, which are charged using energy recovered during braking (recuperation). The developers of the light-duty hybrid truck expect it to achieve fuel savings of up to 20 percent in the regional delivery applications for which it’s currently being tested.

The 12-ton version of the Atego BlueTec Hybrid is designed for heavier shipping, and its parts have been adapted accordingly. The vehicle is powered by a four-cylinder diesel engine delivering 160 kW (218 hp) and 810 Nm torque, plus an electric motor with a maximum output of 44 kW and maximum torque of 420 Nm. When used in tandem, the two perform on a par with a truck equipped with a powerful six-cylinder diesel engine. Thanks to its light four-cylinder engine, and despite the additional hybrid components and lithium-ion batteries, the Atego BlueTec Hybrid is only 60 kilograms heavier than its conventional counterpart.

Alternative drives worldwide

While developing the hybrid drive system for the Atego, Daimler engineers called on the experience of their colleagues in Japan, where the Group already has 200 light-duty Fuso Canter Eco Hybrid production trucks on the road. In fact, some 3,000 alternative-drive vehicles from Daimler Trucks and Daimler Buses are currently in operation worldwide. All of them have been extensively tested, and together they form the basis of Daimler’s global “Shaping Future Transportation” initiative aimed at promoting the use of fuel-efficient, low-emission commercial vehicles around the world.

Shaping Future Transportation - Buses and Trucks

Many vehicles with efficient drive systems, some of which run on alternative fuels, are already in use today around the world 100,000 Mercedes-Benz BlueTec trucks 900  MB Citaro Compressed Natural Gas buses 600  MB Econic Natural Gas Technology trucks 1.100  ORION hybrid buses 200  Mitsubishi Fuso Canter Eco Hybrid trucks 36  Mercedes-Benz Citaro fuel cell buses