PHEVs with ICE driven generator together with storage battery and control units have been on the market for many years and should not be the subject of further patent rights to limit market applications. An old GM trick?

I wonder how they keep the pistons cool, PM dont like a lot of heat or shock.

Im interrested to buy if the overalll mpg increase and if the price of the entire vehicle is not higher. Gm seam to be the leader in green technology with the volt, then this new technology. This will be maybe cheaper then what it replace as they said that the pistons are free.

The possibility on this type of ICE generator-alternator to be mass produced and come to the market place in lower cost PHEVs is very minute. High performance, light weight, lower cost, 120+ kWh batteries may be around years before.

This is another PR move by GM to convince the lower and middle classes, in USA and Canada, that the $40+B bailout was justified. More will come on a regular basis?

It strikes me that this enables you to run your generator at peak efficiency over a much wider range of powers, by completely disabling the units you don't need - which is good.
On the other hand, you now end up with 3-4 ICE engines, where you used to have only 1, adding complexity.

Also, the 4 cylinders will all be different sizes (for different powers), so it is not as if you have 4 engines of the same size, you have 4 engines of different sizes.
Hence complexity and cost of design and manufacture.

Still it is very interesting and I hope they build some prototypes.

I wonder what the engine(s) would sound like with 0-4 engines running at any given time.

"GM haters can turn the reality of GM's progress and breakthroughs in green technology into their paranoid world world as evidence of the imagined evil."

frankbank, there is nothing imagined about GM's conviction:

http://en.wikipedia.org/wiki/General_Motors_streetcar_conspiracy
http://en.wikipedia.org/wiki/Patent_encumbrance_of_large_automotive_NiMH_batteries
..
or http://www.cbsnews.com/8301-505123_162-57551668/gm-opens-new-plant-for-chinese-budget-brand-baojun/
http://www.4-traders.com/GENERAL-MOTORS-COMPANY-6873535/news/GM-Confirms-Plans-For-$1-Billion-Russia-Investment-By-2018-14477750/ ..

Many respect what US Ford has done with marketed, high mpg power trains and models, esp. EcoBoost and the C-Max, while GM has it's track record.

Since overpaid DC idiots decided "Corporations are people too"('Citizens United'), GM is an ex-con.

With GM now putting taxpayer $billions into Asia, some question the 'ex'.

Try stepping away from the myth that normal bankruptcy, without giving the GM assets to the unions and giving the new GM much favored treatment, would have ended GM.

Fisker, and even GM, eventually figured out that a generator-to-battery-to-motor configuration does not result in peak MPG.

Varying the configuration of the internal combustion engine matters not. Directly driving the wheels like the Prius is the efficient way to go when burning fuels.

The motors can always be driven (without the engine) by batteries whenever necessary, when battery capacity allows.

This is a very good development in the area of energy conversion. Using permanent magnet in high temperature environment is a concern but there may be other ways to overcome this limitation. Using opposing pistons will cancel or reduce vibration related issues.
The main benefit I see with this engine is the ability to control the power flow precisely by electronics. The mechanical energy in the piston needs to be transferred synchronously by tracking the induced emf in the stator coils. Power electronics and control method are very well established for this( linear induction motor controls, magnetic levitation controls, etc) though there may be some critical issues related to tracking continuously varying emf. Overall, it will eliminate many mechanical connections that are inherent in a rotary engine and alternator solution and that by itself should help improve the efficiency of energy transfer. It will be interesting to see when they build some prototypes of this concept.

This conjecture is all absent data. We can't know if free piston gen sets are better or worse well-to-wheels unless and until we know how efficient they are at converting BTUs of fuel into electric power. Yes there are conversion losses, potentially several if the energy is stored in a battery or capacitor en route to the motor. However, if the Free Piston ever achieves greater than 50% thermal efficiency (which was the goal set out by Sandia when they announced their partnership with GM and U Mich. http://www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2011/adv_combustion/ace008_vanblarigan_2011_o.pdf)...then maybe the well-to-wheels will be superior...especially if the get good at producing almost the exact amount of power needed for the motor, with minimal storage conversion losses.

By the way, I don't see how GM gets this patent when there appears to be prior art 14 years earleir at http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA294318.

The perspective is missing behind this interesting article : We're headding to PHEVs optimized arround much larger battery packs, like Tesla Model S & X top bin at 85KWH. Not only these batteries provide much more capacity, but also much more instant power, allowing to move to a drive train exclusively tracted by electric engines, even at maxi power demand points at high speed on mortorways and on mountain roads, the ICE Range Extender being only used as "accasional power Generator to extend the EV car range and eventully also recharge the battery pack once exhausted. These Rage extenders can work at constant speeds, but must me small, efficiant, and reliable when only used a few times per year for longer vacations trips for ex. They will be used more and more rarely and need be reliable used that way and still efficiant. Is that techno good for this and to what extend ?

I understand the never-tracting and more and more rarely used range extender ICE Generator engines required for next gen PHEV, could be a different techno than current Gazoline and Diesel Engines established as kings of tracting ICE engines today. So far my bet was this would grant a second life to Micro Gaz Turbines or Rotative engines, but I'm missing objective datas comparing their reliability for few times per year usage, as well as their efficiency to generate the Electric power required for the battery, compared to the current std ICE engines and the alternative one covered here. Basically nirvana for me, if we assume 500Miles can be completed with 70 litters of Diesel, or 130KWH of EV battery, would be an engine consuming less than 70L of Diesel to rechange 130KWH, or <46L for 85KWH... Is that possible in a reliable way for rare usages each year ? (With 85KWH giving >300M range, I could leave with one full charge per week for my wekly local commutes during the year, plus an extra charge for most week ends outside home, and only a few litters of Petrol for very few long vacation trips 2 or 3 times per year maximum in my case...)

A new solution introduced by the site www.hybrid-engine-hope.com describes an alternative range extender configuration. This concept can be used for hybrid vehicles or for electric vehicles with extended range.