|The Volvo Hybrid 7700. Click to enlarge.|
Volvo has unveiled the hybrid version of its 7700 bus at the IAA Commercial Vehicles Show in Hanover, Germany. (Earlier post.) With up to 30% lower fuel consumption and cost-effective hybrid components from Volvo, bus operators can earn a payback on the extra cost in five to seven years, according to the company.
The 7700 Hybrid features a parallel hybrid system with the Volvo MD5 diesel engine and Integrated Starter Alternator Motor (I-SAM). The 4-cylinder, 4-stroke turbocharged and intercooled in-line diesel engine delivers 158 kW (212 hp) of power at 2,200 rpm and 800 Nm (590 lb-ft) of torque at 1,200 to 1,700 rpm. Continuous output from the I-SAM motor is 70 kW (94 hp), with 120 kW (161 hp) peak; continuous torque is 400 Nm (295 lb-ft), with 800 Nm peak. A 600V, 4.8 kWh Li-ion battery pack is roof-mounted and water-cooled.
The engine uses a 1,600 bar common rail fuel system, and Volvo EMS2.2 engine control system. An SCR catalytic converter reduces NOxemissions; the bus is Euro V and EEV compliant. The I-shift automatic gearbox offers 12 forward gears and 4 reverse.
The lower fuel consumption reduces CO2 emissions of the greenhouse gas CO2 by up to 30%. Emissions of PM and NOx drop by up to 40-50% compared with the diesel version.
As a parallel hybrid, the bus can be powered by the electric motor or the diesel engine independently and well as by both engines simultaneously. As a result, the bus could be equipped with a smaller, 5-liter diesel engine compared with the 9-liter engine in the diesel version of the Volvo 7700, Volvo said. The bus’s performance is enhanced, but fuel consumption is reduced.
Volvo attributed the claimed up to 30% reduction in fuel consumption in part to its developing all the hybrid components itself, allowing it to optimize the vehicle. With other hybrid bus hybrid solutions, the bus also becomes substantially heavier and, consequently, can carry fewer passengers. By contrast, the Volvo 7700 Hybrid weighs only 100 kg more than a diesel version. As a result of better weight distribution, it can carry up to seven more passengers than its diesel counterpart.
The first buses will be delivered to customers during 2009, while mass production begins in early 2010.
Volvo is applying its I-SAM parallel hybrid system in vehicles across the Group, including trucks and construction. Long term, this will involve larger volumes, reducing costs further, the company said.