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The variety of electric drive systems: Concept BlueZERO

With the Concept BlueZERO Mercedes-Benz showed the way ahead in environmentally responsible electromobility at the North American International Auto Show (NAIAS) in Detroit in January 2009. This was a modular concept which, based on a common vehicle architecture, made three vehicles with different drive configurations possible.

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Mercedes-Benz Concept BlueZERO, concept vehicles for different electromobility variants, presented at the North American International Auto Show, Detroit, in January 2009.

Facts

Vehicle1: BlueZERO E-Cell

Vehicle2: BlueZERO E-Cell PLUS

Vehicle3: BlueZERO F-Cell

When: January 2009

Where: North American International Auto Show, Detroit

What: Flexible platform for different electro-mobility solutions

Technical highlights

Modular drive concept based on the Mercedes-Benz sandwich-floor architecture

Translucent surfaces in lightweight components such as the tailgate allow the aluminium structure to be seen

Consistent integration of drive and energy storage technology represents a design advantage over other electricity-powered vehicles

The three variants were based on the unique sandwich-floor architecture, which Mercedes-Benz introduced from the mid 1990s onwards, one of the aims being the integration of alternative drive systems for the A- and B-Classes. Advantages of the modified design included the fact that the relevant drive components were installed beneath the vehicle floor in a space-saving, protected location. In terms of lightweight construction, interior and bodywork design too, the five-seater BlueZERO studies also set standards.

Powertrain

BlueZERO E-Cell: battery-electric drive, 100 kW (70 kW continuous output), energy supply via lithium-ion accumulators, a range of up to 200 kilometres

BlueZERO E-Cell PLUS: electric motor, 100 kW (70 kW continuous output), energy supply via lithium-ion accumulators and three-cylinder petrol internal combustion engine (50 kW/68 hp) as Range Extender, an overall range of up to 600 kilometres, up to 100 kilometres under electric-power alone

BlueZERO F-Cell: electric motor, 100 kW (70 kW continuous output), energy supplied via a hydrogen-powered fuel cell. Range with one tankfull: 400 kilometres

The Concept BlueZERO offered the following convincing advantages over electricity-powered cars based on conventional vehicle platforms and originally designed only for the use of internal combustion engines:

Interior space offered by the vehicles was retained in full. Thanks to the integration of the drive components in the spacious sandwich floor, neither the passenger nor the luggage compartments had to suffer any reduction in size or variability whatsoever.
The drive engineering components installed in the sandwich floor produced a low centre of gravity. This favoured a particularly reliable and agile handling.
Thanks to the sandwich concept and the location of major drivetrain components between the axles, the vehicles’ crash safety was of the accustomed high level typical of Mercedes‑Benz.

As a result, the BlueZERO models were very different from conventionally-built electricity-powered vehicles, which had to accommodate heavy, bulky storage batteries in the boot or in the rear seat area.

Front-wheel drive



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Mercedes-Benz Concept BlueZERO: modular concept for electromobility

All three BlueZERO models featured front-wheel drive, which is typical for this class of car. They had identical components, stemming from a modular construction principle, among these the liquid-cooled lithium-ion accumulator with a storage capacity of up to 35 kWh.

With a charge of 15 kW the lithium-ion batteries of the BlueZERO E-Cell and the BlueZERO E-Cell PLUS were able to store energy for a distance of 50 kilometres within 30 minutes. Operating under purely electrical energy a charging time of one hour and two hours were necessary to cover distances of 100 and 200 kilometres, respectively. With a charge of 7 kW, as that provided by a normal three-phase current connection, requires twice these charging times. But it was also possible to recharge the vehicles using a conventional household socket. For both these vehicles electronic systems were also planned to support the intelligent charging stations and billing systems.

Range extender



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	Mercedes-Benz Concept BlueZERO E-CELL PLUS, battery-electric powered concept vehicle with internal-combustion engine as range extender

The BlueZERO E-Cell PLUS was also equipped with the same 1.0-litre turbocharged internal-combustion engine as the smart fortwo, as an additional range extender. The compact three-cylinder engine, installed in the rear of the vehicle, delivered a continuous output of 50 kW at an engine speed of 3500 rpm, recharging – via an alternator of the same output – the 17.5 kWh lithium-ion battery while driving according to requirements. This enabled the vehicle to achieve a maximum range of 600 kilometres with one tankfull. The range under electric power alone was of up to 100 km. NEDC (New European Driving Cycle) consumption was 4.5 litres per 100 kilometres. In conjunction with a plug-in battery the vehicle could achieve a carbon dioxide emission level of just 32 grams per kilometre.

Fuel-cell technology



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Mercedes-Benz Concept BlueZERO F-CELL, battery-electric powered concept vehicle with fuel cell as energy converter from hydrogen to electric power

The new fuel cell generation used in the BlueZERO F-Cell was more compact yet with a maximum output of 90 kW (continuous output 80 kW) at the same time more efficient than its preceding version. Its cold-start capability extended down to 25 degrees below zero. In addition, the system was characterised by low recharging times. The BlueZERO F-Cell was capable of attaining a range considerably in excess of 400 kilometres (NEDC, New European Driving Cycle) without generating any local emissions.

In practise this compact family car met high handling dynamics standards, but only consumed 2.9 litres of fuel (diesel equivalent) per 100 kilometres. In this variant of the Concept BlueZERO, too, the drive system components (in this case electric motor, high-voltage battery and hydrogen tank) were located in a space-saving manner beneath the passenger compartment. The system used the most efficient energy source in each handling situation, so that the electric motor operated using only battery current when parking or manoeuvring. When accelerating both the electric battery and the fuel cell together delivered the required energy. When braking the electric motor acted as a generator, recharging the battery. This way, the efficient system made use of the energy which in conventional braking systems is converted into heat, storing the energy in the lithium-ion battery.

With the BlueZERO concept studies, Mercedes-Benz provided a very concrete view of the future prospects for electric drive systems. Basic components of the modular drive concept were conceived for future series-production vehicles from Mercedes-Benz. The modular building-block system enabled tailor-made drive solutions for individual requirements to be designed. A first result was the Mercedes-Benz B-Class F‑Cell with a fuel cell- powered drive system that started series production in 2009.