Mercedes-Benz Commercial Vehicles and Buses: Electric all the way
As one of the world's leading manufacturers of trucks and buses, Daimler has always demonstrated its clear commitment to environmentally friendly innovations. In the case of commercial vehicles, both elements have to be right: economy and ecology. Which is why, going forward, the systematic further development of the company's highly efficient diesel engines will go hand in hand with the availability of locally emission-free electric drive systems in all segments: the FUSO eCanter for light-duty distribution operations in Europe, Asia and America, and the electric Mercedes-Benz Truck for heavy-duty distribution transport purposes. In the USA, Freightliner continues to work on an electric eCascadia for long-distance duties. The Citaro hybrid urban bus is already in standard production, and is to be followed by the first series-production battery-electric urban bus in 2018.
Until just a short while ago, the use of all-electric drive systems in trucks seemed unthinkable – above all because of the high costs for the batteries, coupled with a limited range. Technology has now moved on significantly. Progress with the development of battery cells in particular has been rapid: Daimler Trucks anticipates that by 2025 the costs for the batteries in a fully electric truck will have fallen by a factor of 2.5 since 1997 – from 500 euros/kWh to 200 euros/kWh. Over the same period, the output will have risen by the same factor from 80 Wh/kg to 200 Wh/kg.
The truck unit of Daimler AG is now underlining its commitment to customer-oriented electric vehicles with a new cooperation: Daimler Trucks is investing in the Israeli company StoreDot Ltd., a pioneer of nanotechnology materials and their use for ultra-fast battery charging. The strategic partnership will focus on the rapid charging of batteries. Using StoreDot's FlashBattery technology, the experience of charging an electric vehicle will be on a par with that of conventional refuelling. The technology is also extremely efficient in terms of energy recuperation. Daimler and StoreDot will continue to work together on this technology. The next generation of the FUSO eCanter might, for example, be a potential area of application.
The FUSO eCanter distribution truck: in standard production since July 2017
The Fuso Canter E-Cell light-duty electric truck has been undergoing commercial fleet testing since 2014. And on 14 September 2017 the global market introduction of the new FUSO eCanter began. It is the first series-produced fully electric light-duty truck in the world and will be making its way to customers in the US, Europe and Japan before the year is out. Over the course of the next few years, Daimler subsidiary Mitsubishi Fuso Truck and Bus Corporation (MFTBC) is planning to deliver a total of 500 trucks from this model generation to selected customers. Large-scale production is due to start in 2019. During the official market launch, FUSO was also able to announce its first commercial customer for the USA: logistics operator UPS will be using the electric truck in future to ensure that its deliveries are made in a more environmentally compatible and sustainable way. In Japan, supermarket chain Seven-Eleven Co., Ltd. will be taking 25 eCanter onto its fleet.
Depending on the specific body and type of deployment, the eCanter has a range of 100 km and offers a payload of up to three and a half tonnes. The electric powertrain of the vehicle is made up of six high-voltage lithium-ion batteries, each providing 420 V and 13.8 kWh. This means that, by comparison with a conventional diesel version, a saving of up to 1000 euros per 10,000 km can be made in terms of operating costs.
Following years of intensive research and customer testing, the FUSO eCanter is now fully integrated into the production line for the conventional FUSO Canter. Production began in July in Tramagal, Portugal, the manufacturing location for all eCanter vehicles for the European and US-American markets. Taking the place of a diesel unit, an electric powertrain with a strong permanent-magnet motor delivers an output of 115 kW (156 hp) to the rear axle via a single-speed transmission. 285 newton metres of torque allow the six-tonne vehicle to accelerate almost as fast as a passenger car, and are available from the very first second of driving. As with all vehicles in this weight category, the maximum speed of the eCanter is limited to 80 km/h. The batteries, weighing in at around 600 kg, allow a range of more than 100 kilometres - in many cases more than the total distance covered in a day by a light-duty distribution vehicle.
Electric Mercedes-Benz truck: fully electric up to 26 tonnes
In the category above the FUSO eCanter, Mercedes-Benz presented a fully electric truck with a permissible GVW of up to 26 tonnes in the autumn of 2016. So now there is even a heavy-duty truck that can move around virtually silently and with zero local emissions in an urban distribution transport scenario. Daimler Trucks envisions the introduction of this technology to the market as soon as the beginning of the next decade. The ongoing development of the electric truck right through to series maturity is a key element of Daimler Trucks' strategy to further extend its technological leadership. To this end, a sizeable proportion of the truck division's future investment in research and development activities will go into the further development of the fully electric drive system.
The technical basis for the electric Mercedes-Benz truck is provided by a heavy-duty three-axle distribution truck from Mercedes-Benz. From this starting point, the engineers at Daimler Trucks have then completely rethought the drive concept: an electrically driven rear axle with electric motors directly adjacent to the wheel hubs replaces the conventional powertrain. The power supply comes courtesy of a battery pack made up of three modules of lithium-ion batteries. The result is a range of up to 200 km – sufficient for a typical day's driving in the distribution transport business. Thanks to the concept of the drive axle with its integrated wheel-hub motors, the batteries could be positioned in a crash-proof location within the vehicle frame.
Since the EU Commission supports an increase of up to a tonne in the permissible GVW for trucks featuring an alternative drive system, the additional weight of the electric drive system of 1.7 tonnes is largely compensated for, as the permissible GVW of the electric truck is thus increased from 25 to 26 tonnes. The payload is therefore only 700 kg lower than it would be for a directly comparable truck with a combustion engine.
In series production from 2018: the battery-electric urban bus
In extending the urban bus manufacturing capability of the Daimler Buses plant in Mannheim, one of the key areas of focus apart from the production of Mercedes-Benz urban and cross-country buses has been the issue of electric mobility: the first series-produced battery-electric bus will be produced at the Mannheim plant in 2018. The necessary development expertise is being built up in Mannheim accordingly.
An electric boost to get across town: the Mercedes-Benz Citaro hybrid
The Citaro hybrid sees Mercedes-Benz opening a new chapter in drive systems for urban buses. In a global first, hybrid technology is not used here in stand-alone models, but is available as an optional extra for a surprisingly wide range of urban buses with diesel and gas engines. Numerous models are thus able to benefit from the advantages: in conjunction with the likewise new electrohydraulic steering system, the drive system of the Citaro hybrid reduces the fuel consumption of the Citaro, already renowned for its efficiency, by as much as a further 8.5 percent, depending on the operating profile and specification. Thanks to the intelligent combination of existing components from within the Daimler Group, the Citaro hybrid offers numerous benefits: it is extremely efficient, lightweight, inexpensive to purchase and unproblematic for drivers and workshops alike. The technology in the new Citaro hybrid is not a transitional solution that will ultimately be replaced by an all-electric drive system, but one that allows Mercedes-Benz to hone the combustion engine in a unique way in order to maximise efficiency.
The electric motor is located between the combustion engine and the automatic transmission and delivers a maximum output of 14 kW along with peak torque of 220 Nm. It is used primarily to boost the combustion engine when high levels of power are required, particularly when moving off. It does not, however, serve to increase the maximum output, which is why the output and torque figures for the bus remain unchanged. The electric motor is instead used to take the strain off the combustion engine and helps to improve performance upon starting up. This does not involve lowering the engine speed of the combustion engine. Instead the peak output is imperceptibly throttled, with the electric motor making up the difference.
In addition, a slight boost effect from the electric motor at idling speed helps to improve the efficiency of the combustion engine. These two functions together translate into a major reduction in fuel consumption. A further key advantage: the Citaro hybrid manages without a complex high-voltage network with all the limitations and safety constraints that that involves. Instead, the urban bus is the first commercial vehicle to feature a separate 48-volt network, as used in Mercedes-Benz passenger cars with a hybrid drive system.
Supercaps provide short-term energy storage
The power needed to drive the electric motor is produced free of charge through recuperation: during braking and overrun phases, the bus's electric motor takes on the function of a generator. The power produced in this way is stored in double-layer capacitors, also known as supercaps. These electrical storage devices are characterised by their high power density. They are resistant to power peaks and have a long service life. Unlike batteries, supercaps are ideally suited to the continuous quick alternation between charging and discharging that occurs when stopping and pulling away again in typical urban bus operation. Braking to a stop from a speed of 50 km/h just once is enough to recharge the power storage units in the Citaro hybrid.
Proven bus, passenger car and truck components
The development engineers behind the Citaro hybrid have relied on proven components and made the most of the close links and wide-ranging experience available within the Daimler Group. These components have been tried and tested, their comparatively high production numbers lower costs and it is easier to supply replacement parts.
The electric motor in the Citaro hybrid, for instance, is already fitted on the new Mercedes-Benz S-Class as a starter-generator. The additional radiator for the electric motor and inverter is used at Mercedes-Benz Trucks, and the water pump is to be found in passenger cars bearing the three-pointed star.
Citaro NGT: climate-neutral driving with organic natural gas
The hybrid drive system is also available for the Citaro NGT equipped with the M 936 G gas engine – the combination of gas engine and hybrid drive system is rarely found anywhere in the world, yet the particularly low environmental impact of the gas engine makes it a highly attractive option. The natural gas-powered urban bus Mercedes-Benz Citaro NGT was launched by Daimler Buses in 2015. Compared with the previous model, the Citaro NGT is as much as 20 percent more efficient. In using organic natural gas, it is also almost completely CO2-neutral. In some cases it significantly undercuts the extremely stringent Euro VI emissions limits. Its almost soot-free combustion also means that there is no need for the SCR technology with AdBlue injection that we know from the diesel engine, nor for a particulate filter.
With an average of around 10,500 new vehicles registered each year, the urban bus segment in Western Europe remains at a steady level. The highly specialised sector of natural gas-powered urban buses accounts for about 1000 units each year in Europe. Daimler Buses expects this figure to rise further in future thanks to environmental projects in densely populated areas.
As alternatives to the further optimised drive system with combustion engine, the Citaro E-CELL and Citaro F-CELL represent the next milestones along the way to the future. Both are based on a shared e-mobility platform. Building from this basis, Daimler Buses expects to put a production-standard version of the battery-electric Citaro E-CELL on the road from 2018. In terms of engineering development, Daimler Buses is able to benefit from being part of the Daimler Group, since in their shared objective of achieving locally emission-free driving, all vehicle divisions work closely together. It has been possible, for example, to bundle certain research activities. Furthermore, components such as the fuel cell stacks can be used in both passenger cars and commercial vehicles.
FUSO Canter Eco Hybrid: no other 7.5-tonne model offers better economy or load-carrying capacity
The FUSO Canter with hybrid drive system has been built in Portugal since October 2012. Compared with the conventional Canter model it offers fuel savings of up to 23 percent. The highly sophisticated four-cylinder turbodiesel with a displacement of 3.0 l, output of 110 kW (150 hp) and maximum torque of 370 Nm is taken from this model. The BlueTec 6 engine complies with the Euro VI emission standard, while its exhaust gas cleaning system combines exhaust gas recirculation, SCR engine technology with AdBlue injection and a particulate filter. The electric motor has an output of 40 kW, maximum torque of 200 Nm and is powered by lithium-ion batteries. These have a capacity of 2 kWh and weigh just 63.5 kg. The additional weight of the hybrid drive system amounts to no more than about 150 kg. The load-carrying capacity of the 7.5-tonner as a chassis with cab can therefore be as much as 4.8 t.
The Mercedes-Benz Actros: the perfect blend of economy and ecology
No long-distance truck has ever been so systematically designed for maximum efficiency as the Mercedes-Benz Actros. It is the byword for exceptional economy in the tough transport sector. The introduction of the latest generation of the OM 471 heavy-duty engine brings a further reduction of up to six percent in its already low fuel consumption. Instrumental are improvements in many details: All heavy duty engines now use low friction oils, the 12-speed gearbox Mercedes PowerShift 3 has been optimised, and cruise control Predictive Powertrain Control (PPC) employs an improved drive strategy. Additionally, there are aerodynamic improvements to the Actros. Overall, the improvement of six percent in efficiency proves once again the superior results of in-house developing, and producing, engines, transmissions and axles.
This all comes courtesy of the sophisticated technology of the in-line six-cylinder unit with a displacement of 12.8 l, an output of up to 390 kW (530 hp) and torque of up to 2600 Nm: dual overhead composite camshafts, the unique common-rail injection system with X-Pulse pressure booster, the asymmetric turbocharger, the powerful engine brake and an emission control system based on SCR technology, exhaust-gas recirculation and particulate filter in order to meet the stringent Euro VI emissions standard.