When talk turns to improving fuel vehicle economy, two
technologies are likely to enter the discussion: hybrid petrol/electric
drivelines like that used in the Toyota Prius and high pressure common rail
diesels fitted to vehicles from makers like Audi, Peugeot, and Mercedes.
European manufacturers have long championed diesels, while
Japanese company Toyota has an apparently unassailable lead in hybrids. Despite
German automotive electronics powerhouse Bosch being a prime mover in the
development of car electrics and despite Toyota building and selling diesel
passenger cars, the obvious step of combining frugal diesel power with low
emissions hybrid technology hasn’t yet occurred.
Or has it?
Coming in from left field is a completely new player – GM
Allison. GM currently sells some ‘soft’ hybrids but it is their heavy vehicle
transmission arm Allison that is the dark horse in hybrid technology
Not only has Allison developed a high efficiency, patented,
two-mode hybrid transmission but it is a self-contained unit that can be bolted
to a variety of different engines – including conventional diesels.
Rather than being controlled by the engine management system,
the Allison EP system controls the engine via a standard communications
interface, allowing it to work with a range of engines.
The Allison EP system is currently available in two
configurations, both primarily suited to heavy vehicles that work in a
stop/start environment such as urban buses and garbage trucks. However, GM and
partners DaimlerChrysler and BMW will soon incorporate the technology in hybrid
passenger cars, potentially providing some real competition for Toyota and
Honda. So what do the heavy vehicle systems consist of and why has the
technology implications for fuel-efficient passenger cars?