DETROIT - Six-cylinder engines may be the cutoff point between using a bolt-on stop-start alternator or an engine-changing integrated starter generator.
Bigger engines need more cranking power than the external alternator systems can provide, said engineers for Mannesmann Sachs AG.
The supplier displayed a 90 percent efficient integrated starter generator at the SAE World Congress in early March.
Martin Sattler, supervisor for production of electric drive systems, said Sachs is supplying production versions of its starter-generator to luxury vehicle manufacturers in Europe, and is in talks with a North American luxury vehicle producer. Sattler would not name the manufacturers in either case, but said European agreements are in place and high-volume production of the starter-generator is expected in 2004.
'It is a problem to use a belt-driven starter generator with large engines,' Sattler said. 'I do not think it is possible to start a six-cylinder engine, under cold conditions, with a belt-drive machine.'
Delphi Automotive Systems and Visteon Corp., have introduced concept starting systems that would use a belt-drive inductive starter-generator in place of the current alternator on cars - but not for traction uses.
Delphi Research Labs engineer Rassem Henry, addressing an SAE technical session, said such starter generators require less engineering disturbance because they fit in existing space at the front of the engine, while the serpentine belt drive they use is comparable to reliable, existing technology.
Delphi experiments found that the water-cooled 42-volt machine can produce up to about 3.4 kilowatts of power in a steady state.
Near-future cars are expected to demand just about that level of power, considerably higher than today's 14-volt systems. Many engineers, though, predict that cars will soon demand more than 8 kilowatts of power.