Jul 13, 2005 (From the CalCars-News archive)
Until now we had only press release pages from DaimlerChrysler -- this page, including technical descriptions, photos and illustrations, had escaped our attention until now (it's dated November 2004). We've added links to it at CalCars.
The first 4 Sprinter diesel PHEVs are expected to arrive in the U.S. later this summer, with NiMH batteries from Varta (Johnson Controls) and Li-Ion batteries from Saft.
Note that on their website, Brusa (the Swiss company whose charger is used by CalCars in developing our prototypes), points out that the Sprinters use their NLG-5 charger. http://www.brusa.li/news/e_news.htm
The Dual-Drive Sprinter - Vans equipped with hybrid drive systems
Zero-emission driving: The Mercedes-Benz Hybrid Sprinter’s electric drive ensures quiet and emission-free driving in inner cities - and a big improvement in quality of life for these areas.
Stuttgart, Germany, November 29, 2004
Summer in the city: The air seems almost still in the early morning. People on their way to work cast a critical eye at the vans moving through the city’s pedestrian zones and making deliveries to the various cafés and boutiques located there. Soon it will be very hot and exhaust gas will begin to fill the streets beneath the city’s tall buildings. As annoying and unhealthy as the exhaust gases are, the businesses in the inner city need to have their deliveries.
CAPTION: The hybrid Sprinter of Mercedes-Benz is powered by a four cylinder diesel engine generating 80 kW/109 PS and an electric engine with a maximum output of 70 kW/95 PS.
One example from DaimlerChrysler’s Commercial Vehicles division shows exactly how to reduce air pollution due to delivery traffic in the inner cities: the new “Hybrid Sprinter” presented by the company at this year’s IAA Commercial Vehicles show at the end of September. The addition of the electric motor installed in the vehicle enables it to run without producing any exhaust gas whatsoever.
CAPTION: Both engines transfer their torque to a common drive shaft, thus eliminating need to modificate differential gear or chassis.
“We used the Sprinter 311 CDI with automatic transmission as the basis for the new vehicle,” explains Karl-Heinz Keller of the Competence Center for Zero Emission Commercial Vehicles in Mannheim, Germany. “The Hybrid Sprinter’s electric motor, which is integrated into the powertrain between the transmission and the clutch, obtains its energy from a drive battery located underneath the vehicle floor.” This sophisticated setup for the additional drive unit means that the innovative van’s entire cargo area can be utilized without restrictions, which was a key factor in ensuring that the vehicle would be accepted by shipping companies.
But the Hybrid Sprinter offers a whole range of other advantages as well. It is not only capable of operating emission-free in inner cities and other areas prone to congestion - for example, sports arenas and convention centers - but is also very quiet. In addition, its combustion engine and large diesel fuel tank ensure that there are no restrictions on the vehicle’s range. On the contrary, depending on how it’s used, fuel consumption, and thus CO2 emissions, can be reduced by up to 50 percent, meaning that vehicle operators can cover a greater distance on one tank of diesel than was previously the case.
The clever combination of a diesel engine and an electric motor (experts refer to this drive concept as a “parallel arrangement”) makes for optimal operation of the Hybrid Sprinter in any situation. Drivers can select the drive they wish to use with just the push of a button.
Well hidden: The electric motor is flanged onto the transmission, which is located above the black crossrail in the underbody. Thus it is perfectly integrated into the powertrain.
In the hybrid mode, the combustion engine and the electric motor power the vehicle alternately in line with one of the various operating strategies stored in a control computer. In order to ensure optimal fuel consumption and battery utilization, these strategies take into account current driving conditions, the position of the gas pedal, and the battery’s charge.
At low speeds - for example, while making deliveries in pedestrian zones, at hospitals, or in convention centers - drivers can simply push a button to put the vehicle into its quiet, emission-free mode with the electric motor.
The third driving mode has both the diesel engine and the electric motor operating simultaneously. “This boost-function, as it is known, is most useful when the vehicle is accelerating or climbing a hill and needs a lot more power than usual,” says Keller, “It engages when the driver pushes the gas pedal to the floor.” The additional torque supplied by the electric motor in this situation takes some of the burden off the diesel engine, thus reducing the latter’s fuel consumption.
There is also a “fourth dimension” of hybrid driving with the Sprinter. Known as “recuperation,” it involves a reversal of the energy flow: Whenever the vehicle brakes or travels downhill, the wheels are used to drive the electric motor via the transmission. As a result, the electric motor becomes a generator that recharges its own battery with the electricity it produces. In other words, hybrid vehicles are capable of recovering part of the energy they consume. Two electric motor options
DaimlerChrysler engineers have developed two variants of the new dual-drive Sprinter. In the “Plug-In” van model, the diesel engine is accompanied by a 70-kW electric motor and a socket for charging the battery.
CAPTION: The only external difference between the Plug-In Hybrid Sprinter and a conventional production van is the flap housing the socket for connecting the battery to a power source and charging it overnight.
The other version of the Hybrid Sprinter has no charging socket and is equipped with a somewhat smaller electric motor producing 30 kW of output. This motor’s battery has a capacity of three kilowatt-hours, which translates into a range of three to four kilometers when the electric motor is used exclusively - enough for operation in just about any pedestrian zone.
In addition to its more powerful electric motor, the Plug-In Hybrid Sprinter is equipped with a higher-performance electricity storage unit - a nickel-metal hydride battery (NiMH) with a capacity of 14 kilowatt-hours, enough for 30 kilometers of driving in the pure electric mode. The battery can be charged through the 230-volt public network. Charging should be done at night, however, since it takes six hours to recharge a completely dead battery.
Along with its tremendous range, the Plug-In variant will also offer its future customers another technical highlight: Craftsmen, fire departments and other service organizations will be able to charge the electric motor with the diesel engine when the vehicle isn’t in motion. It will thus be possible to then use the electric motor as a generator with an output of up to 40 kW to run power tools and operate pumps.
Despite their different electric motors and batteries, the two Hybrid Sprinters also have some things in common that set them apart from conventional vans. For example, because features like power steering and power brakes need to function even when the combustion engine isn’t in operation, the engineers in Mannheim also equipped the vehicle with an electrically operated vacuum pump for the brakes, an electrical auxiliary steering pump, a compressor for the air conditioning system as well as a fan and a water pump for the engine and battery cooling system.
Two fleets to undergo customer testing
Customer testing of the first new Hybrid Sprinters will begin in early 2005. After being delivered, they will be operated in Europe and the U.S. as delivery vans and service vehicles for power companies, and will also serve as public transportation vehicles. “We want to test the vehicles under customers’ everyday conditions over the next one or two years and channel the knowledge gained into the next generation of the Hybrid Sprinter,” Keller explains.
Although the two vehicle fleets involved will be tested in customer operations, they will officially remain in the hands of DaimlerChrysler engineers so that they can be further optimized if necessary. One area where experts believe there is room for improvement is the vehicles’ weight. In particular, the heavy NiMH battery in the Plug-In Sprinter makes for additional weight of more than 350 kilograms resulting from the electrical system. If a lithium-ion battery with the same output were to be used instead, the additional weight could be reduced to just 160 kilograms. This, however, would also lead to significantly higher costs.
CAPTION: Cleverly placed: Arranging the battery underneath the floor behind the rear axle makes it possible to use the van’s entire cargo capacity.
“When we look at the overall balance of a hybrid drive, we do of course have to be frank about the reduced payload and the additional costs generated by the second drive unit,” reports Keller. However, he also has some good news for potential customers with regard to procurement costs, as nine countries in the European Union are already providing direct subsidies or tax breaks for customers who purchase hybrid vehicles.
Drivers of hybrid vehicles can also expect other benefits from the public sector. For example, natural-gas-powered and hybrid vehicles are exempt from the fee charged for cars and trucks entering downtown London, and drivers of hybrid vehicles can park for free in San Jose, California. Los Angeles is planning to implement a similar rule with the aim of making zero-emission driving more appealing to motorists.
Interim solution on the way to fuel cells
Hybrid vehicles can be expected to become more and more important in the coming years, as emission standards become more stringent all over the world and manufacturers attempt to further reduce fuel consumption. In expressing DaimlerChysler’s position on this issue, Keller explains: “By combining the proven components of the combustion engine and the electric motor, hybrid vehicles offer an ideal interim solution until the time comes when fuel cell drives are ready for series production.”
Putting alternatives on the road
DaimlerChrysler’s Competence Center for Zero Emission Commercial Vehicles (German initials: KEN) in Mannheim was established in 1996. Its approximately 35 employees develop and test alternative drive systems for vans and trucks. They also build small lots of vehicles equipped with these technologies.
For example, the experts at the center not only equipped a Sprinter with the hybrid drive system but also developed a variant with a purely electrical drive. They’ve also developed Sprinters with a combustion engine powered either by natural gas (NGT) or liquid gas (LPG). The most recent Mercedes-Benz vehicle produced that runs on natural gas, the E-Class NGT, was also co-developed by KEN, as was the NGT Econic, which is used for garbage collection.
The KEN engineers also work on the development of fuel cell vehicles. In fact, they made a major contribution to the development of the Citaro fuel cell buses that are now being tested in everyday service. Despite KEN’s relatively young age, DaimlerChrysler actually has a long tradition of involvement with zero-emission vehicles: Back in 1908, a “Mercedes Electrique” model was rolling through the streets of Mannheim.