Could compressed air lead to markedly smaller engines?
A 1.0-liter two-cylinder that performs like a 3.0 liter V6? On what planet? Researchers at Switzerland's ETH Zurich school of engineering are developing pneumatic hybrid engines that use compressed air to deliver big performance and efficiency from a small package. During deceleration, the engine's pistons are used to compress air, which is diverted through a special valve and into a holding tank. Rather than try to propel the vehicle directly with compressed air, like Guy Negre's hybrid system, ETH Zurich's setup uses the compressed air as an instant supercharger to gap where a turbocharger would be spinning up. The goal is to offer much more efficient engines for less money than electric hybrids. Buyers in China or India can't afford the expensive premium that current hybrids command, so something less expensive has to be found. The compressed air systems would achieve 80% of the benefit while only costing 20% more. Dropping the cylinder count reduces frictional and pumping losses, and technologies like direct fuel injection and HCCI can offer diesel-like efficiency out of a gasoline engine. A small, turbocharged two-cylinder with a compressed air system for oomph when needed could return more than 100MPG in a small, light vehicle. Doesn't sound so crazy now, does it?
[Source: Wards Auto | Photo: Wards]
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Reader Comments (Page 1 of 2)
remy 9:11AM (2/26/2009)
Very very, interesting. These guys are spot on, a 2 cylinder engine is all you need for highway use and instant turbo power to pass or accelerate? I'd take that over a normal gutless 4 cylinder anyday.
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Yikes 9:23AM (2/26/2009)
Very interesting idea.
notYou 8:33AM (2/27/2009)
+1
Very interesting idea. I'm not an engineer so I can't testify to the validity, but I'm presuming if they're this far along that there's real gold in them thar hills. Kudos!
naggs 2:15PM (2/26/2009)
this is clearly a great idea, i want
BigMcLargeHuge 9:12AM (2/26/2009)
"The compressed air systems would achieve 80% of the benefit while only costing 20% more. "
I'm assuming they mean 80% of the benefit of hybrid fuel economy while only imposing 20% of the premium of a gas-electric drivetrain.
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Corey W. 10:07AM (2/26/2009)
You're like me, I think that was a typo, if not I don't see the benefit....
Matt 8:55PM (2/26/2009)
Yep thats exactly what they mean.
Sounds promising
Carlos 9:40AM (2/26/2009)
I would buy it!
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BoneHeadOtto 9:40AM (2/26/2009)
Curious how they will handle the ballance issues of 2cylinder. I have always heard they are fundamentally unballanced engines that are extremely rough. I did read about a 2 cylinder diesel motorcycle that had this dual crank shaft design that eliminated the ballance issues. Incorporating that tech might be a good idea as well.
But if this really works as advertised then please make mine a 2.0L 4cylinder so it will have the power of a 6.0L V12 :)
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BigMcLargeHuge 10:06AM (2/26/2009)
They could use a verticle-parallel twin or a horizontal-parallel twin engine.
Those are much easier to balance than V-twins, and are used in lighter motorcycles.
naggs 2:18PM (2/26/2009)
2 cyl work great in labs, in a car, balance and NVH force some design changes.
Kitko 9:48AM (2/26/2009)
Turbocharged 1.5 liter V6 engines in the mid-80s F1 cars produced over 1000 hp.
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Corey W. 9:59AM (2/26/2009)
Weren't they VERY expensive??
Craig 10:02AM (2/26/2009)
And resembled a hand grenade...
Kitko 11:55AM (2/26/2009)
Sure, they were :-) But few guys won championships using them so they had to be reasonably reliable in racing conditions.
XGM 9:56AM (2/26/2009)
Sounds very cool, wonder how much you would save in weight compared to a equivalent engine. Also if the system is smaller then a equivalent engine, that would allow for even better aerodynamic shapes witch could be very interesting.
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RedSiBaron 10:00AM (2/26/2009)
i feel compressed air is a brilliant idea... especially since when electric car infrastructures start going into place it gives more readily available hookups for on board compressors in the vehicles...i like this...
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Craig 10:03AM (2/26/2009)
And precharging the air system at home would be just like charging your battery.
BigMcLargeHuge 10:09AM (2/26/2009)
*horizontally opposed twin
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dukeisduke 10:25AM (2/26/2009)
There are some hydraulic hybrid UPS trucks running around right now (read an article in Car and Driver), as part of a test. They use a small IC engine (direct-injection diesel, IIRC) that powers a hydraulic pump, a huge accumulator (2500psi, IIRC), hoses, and a hydraulic motor that turns the rear axle. The only problem is that the hydraulic part is quite noisy, something that would have to be addressed before a system like this goes into a passenger car.
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