From left: Henrik Kloo, coordinator for the Volvo FE Hybrid project, and the Volvo FE Hybrid truck, which is expected to go into production by 2012
Volvo, which claims it’s been working on hybrid powertrains for commercial vehicles since the 1980s, is now ready with its FE Hybrid truck, which utilises parallel hybrid technology for a 20-30% reduction in fuel consumption. The Volvo FE Hybrid will be available for use as distribution trucks and city buses in Europe by around 2012.
‘This is the way forward for inner-city stop-start applications. As fuel prices increase and awareness of climate change grows, everyone is asking what they can do. This is part of the answer,’ says Henrik Kloo, who coordinated the Volvo FE Hybrid project for Volvo Trucks. ‘We ruled out quite a few configurations of hybrids because they were too expensive, and ended up with what is known as a parallel hybrid system, in which you use one electric machine and an automatically-geared mechanical gearbox,’ adds Anders Kroon, director of hybrid technology at Volvo Powertrain, the Volvo Group’s internal producer of powertrain systems.
The Volvo FE Hybrid’s parallel hybrid powertrain uses either the electric motor or the combustion engine, or both together. There is a normal diesel engine and a gearbox, but in between the clutch and the gearbox sits an electric motor and the truck’s on-board electronics allow independent or tandem use of the diesel engine and electric motors, as needed.
‘These two power sources work on the same axle through the gearbox, and that drives the wheels. That means that when you start the truck from standstill, you engage the electric motor because it is better when starting off with heavy loads from zero – higher torque at lower revs. Then when you get up to higher speeds the diesel engine is activated and these two work together, or if the control system feels it is better then the diesel engine can take over. When you are running at high speed it behaves like a traditional truck, but at low speeds is behaves more like an electric vehicle,’ says Kloo.
The battery chosen by Volvo for the Volvo FE Hybrid is a lithium ion-battery that weighs about 200kg. ‘The battery is the ‘Achilles heel’ in all hybrids throughout the automotive industry. Even though there has been significant development with nickel metal hydride technology, lithium-ion technology and super-capacitors as energy storage, there is still a lot of ground to be covered before we have a completely robust system,’ says Kloo.
Lithium-ion batteries have a limited lifespan, but Volvo is aiming for a lifespan of up to eight years for its batteries, depending on driving cycle. ‘That should resemble the lifetime of the truck, maybe with one battery change,’ says Kloo. ‘Here there needs to be a bit of a trade-off as you can have greater fuel savings if you compromise on the lifetime of the battery.’
Small-scale series production of the Volvo FE Hybrid will get under way by around 2012. ‘The result for the customer will be great. Once functionality and reliability have been proven, we will gain trust for these new technologies. I think the Volvo Group has a great product coming,’ says Kroon.
Volvo FE Hybrid: Tech Specs
Diesel engine: Volvo D7 7.0-litre
Power output: 300–340bhp
Electric motor: 3-phase permanent magnet, synchronous electric motor 600 volts
Max power: 120kW
Max torque: 800Nm
Transmission: I-Shift
Batteries: Lithium-ion 600V
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