Greetings, all. I'm a HAH owner, and I've had an idea which I think could significantly improve the mileage of hybrid vehicles. I've applied for a patent on the idea and would like to get this group of hybrid-interested people's opinion on if it would help or not.

The idea is: Use a turbo-charged engine in a hybrid vehicle, decreasing the engine displacement while keeping the horsepower values the same for the car as the non-turbo version. The turbine of the turbo-charger would be attached to a air compressor (as usual) but also attached to an electric generator (perhaps a low-RPM DC generator, or a high-RPM AC generator, unclear at this point). That electric generator would then be used to charge the batteries (if not full) or provide power to the electric motor (when the batteries are full).

I think this would be very helpful to "mild" hybrids, so they use their assist more often, and the "full" hybrids, so they will stay in stealth mode more often.

So, you get:

1. Smaller displacement with the same horsepower for better mileage,
2. More electricity for less reliance on the gasoline motor for better mileage.

Comments are greatly encouraged. I look forward to your comments / responses.

Kyle Roesler

 

a turbo setup is being used on a honda insight. it increases the "lean-burn" window, increases MPGs, and increases HP and torque. check out www.insightcentral.net

 

The idea of smaller displacement but with a turbocharger is certainly something that's been tried many times before. Probably one of the most famous examples of turbocharging for fuel efficiency was the Chevy Sprint turbo. It had a 1.0 liter engine with 70 horsepower, 107 ft-lbs of torque, and would get fuel economy in the low 40's. At the time, this was pretty good performance although still not particularly better than a CRX HF, for example.

Looking at modern-day small displacement turbocharged cars, VW's 1.8T comes immidiately to mind. They're only rated at something like 25/31, but had 150-180 horsepower depending on year/boost level, and I personally drove one from North Carolina to Arizona at 65-75mph averaging 34mpg. That's quite respectable performance for such a powerful engine in a 3000+ pound vehicle but still not really that much better than you might see from an Acura RSX Type-S which has similar speed.

The bottom line is that turbocharging works very well in theory, but in the real world on ordinary pump gas, it seems like turbo engines rarely surpass what a similar highly developed naturally aspirated engine can do. The only exceptions would be turbocharging on something other than gasoline, such as diesels or E85. In both cases, you can run FAR higher boost levels. Typical gasoline engines run 8 to 15 pounds of boost, but a turbodiesel can run up to 45psi of boost, permitting a much greater volumetric efficiency gain. E85 is around 105 octane and again, you could run at least 30psi of boost on a turbocharged E85 engine.

Really what it comes down to is that Honda and Toyota have a huge army of engineers working on ways to make their top dog hybrids more efficient than anyone else's. Both companies have experience with turbocharging and both companies have chosen not to use turbos in their hybrids. I think that's very telling when the companies with the greatest R&D resources have chosen not to implement a certain technology, such as turbos.

 

Interesting idea, especially the turbo-generator coupling. Arguments against that would be the inherently low efficiency of generating, charging, driving electric motor. However, one could argue that in this case (like in brake system kinetic energy recovery) low efficiency does not matter if you recover energy otherwise completely lost. Yet is that truly the case in turbo-chargers? The waste gas energy is actually recovered by increasing combustion efficiency of the ICE. Whether this is a good idea would depend on how the efficiency of a turbo for ICE compares to the efficiency of turbo-generator-charger-electric motor combo.
One other difficulty is that turbos spin at extremely high rpms, well about 100,000. You would have to gear that down (loss of efficiency there!) to obtain viable generator speeds, unless you have come up with a generator design that can work at 100,000+ rpm.

 

Andy, could you elaborate or post a more direct link for that insight. I'm familiar with the little red rocket (heck...got a chance to ride in it) but as far as i know the turbo is hurtting the milage and lean burn was all but gone (Willie was at 65 or so lifetime when i saw it)

 

yeah, looks like he is down to 58.5 now. BOOOO!

here is one link to the other turbo system being worked up:

http://www.insightcentral.net/forum/...pic.php?t=3232


i might just have to try a straight pipe exhaust system (with cats) to see how that works.

andy g.

 

HafNHaf, thanx for pointing me to the turbo mods going on a InsightCentral. Very interesting. When I exchanged msgs with Figgy, he says he is getting better mileage than before with more time in lean-burn. I didn't really imagine a turbo alone would improve mileage on an Insight - but glad to hear it does.

Now, I'm just hoping either Figgy or someone else who has already added the turbo will be interested in adding the additional generator, too, to see if my idea is helpful and how much. I guess finding the right generator to match to that kind of system is the biggest challenge; anyone have an idea where to find a DC (or AC, which would then need to be converted back to DC) generator that can handle 10,000+ RPM without disintegrating???

Kyle (aka Mary Jane, the Author www.karoesler.com for more info on the Author part)

 

You missed a zero there.. turbo spin over 100,000rpm, not 10,000rpm. In fact, very small turbos, such as VW's Borg-Warner K03 can spin over 200,000rpm at full airflow and have a TINY turbo shaft that is most definitely NOT strong enough to hang a generator or anything of that sort off the end.

Picture of a K04 turbo

Click on that link above. That's a K04 turbo, which is similar in dimensions to the K03, but capable of flowing up to 22lb/min, which is good for well over 200 horsepower on a well tuned car. The turbo shaft is tiny, as you can see in the picture. A hypermileage car would want to have an even smaller turbo, like one rated for 12-15lb/min, and would thus have a turbo shaft probably about the size of a large toothpick.