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By now plenty of people have seen concept vehicles like the Chevy Volt and Ford HySeries Drive Edge. One of the biggest advantage of the series hybrid drivetrains in these machines is the flexibility they provide in choosing an auxiliary power unit. With the battery system providing the primary energy source to the electric motor the transient load demands of acceleration are taken off the range extender. This allows the range extender to operate in a constant mode doing nothing more than driving a generator to keep the battery charged.

When an engine operates in a constant mode like that it can be optimized for those conditions. However while the original Volt showed a fairly conventional three cylinder flex-fuel engine, there is also the possibility of using something radically different. We recently covered work being done on homogeneous charge compression ignition (HCCI) engines that can provide significantly reduced fuel consumption and emissions. Unfortunately getting HCCI works best only under certain light load conditions. However the series hybrid may well provide the perfect application for something like HCCI.

During a conversation with GM Vice President of R&D Larry Burns I brought the idea of HCCI and E-Flex and he agreed that the series layout could be a potential application for the new combustion process. Burns said that GM is investigating many different possibilities for the E-Flex power-train because the constant rpm duty cycle allows many ideas that might not have been feasible before suddenly become a real possibility. A whole new world gets opened up by this setup so thing only thing that's certain right now is change.


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    • 1 Second Ago
  • 8 Comments
      • 7 Years Ago
      Let's just get these things on the assembly line so I can trade my car in
      • 7 Years Ago
      Or, it may end up with no engine at all (as in not produced).
      • 7 Years Ago
      Isn't this a no-brainer application for diesel? Reliable, efficient, and constant RPM power.
      • 7 Years Ago
      Yeah, I've suggested this type of engine for the Volt before, though I'm beginning to think I was wrong for bringing it up. A lot of HCCI research is trying to solve problems that the Volt's engine would never have to deal with. While I think HCCI is worthwhile research, and will help both gas and diesel engines get better, I think it would be best for the Volt to have a fairly conventional diesel which is tuned to run at near-constant rpm.
      • 7 Years Ago
      When since we are in never, never land anyway, why not brainstorm about possible range extenders. For instance, what historically has been used for rail, marine and mining and what extrapolations could be made into the future (Co2 levels, peak oil, etc.)

      One possibility in the near future CLEANOVA fans is a specialized, turbocharged, direct injection, combustion ignition engine burning primarily ethanol.

      A design problem will be accommodating existing generations of Otto Mobile users that have depended upon sensory cues (Feel free to sing the words to Hot Rod Lincoln here, if you like?)
      • 7 Years Ago
      Let's just get these things on the assembly line so I can trade my car in
      • 7 Years Ago
      This story is so stupid. GM ALWAYS said that the
      extedned range engine could be this or that, specifically could be an E-85 or diesel or fule cell, or even battery pack. The flexibility of the design allows for just about anything to be used to charge the batterypack. So what's the big imprtant news item that a guy at GM concedes that a new type engine might also be used? This isn't news. This is junk food in print. Wake me up when something of consequence happens in teh VOLT's devlopment (like a satisfactory battery - that is the only missing ingredient). Yawn!
      • 7 Years Ago
      HCCI engines would be great but probably won't be mature enough to put in a first generation Volt. GM should start with both diesels and Atkinson-cycle engines. Or GM could push its engineers a little harder and design a Miller-cycle GDI - two technologies that have yet to be combined in production.