Toyota developing free piston engine linear generator for hybrid cars

[Tom Reed]

Could this work well for a cogen???

http://www.foxnews.com/leisure/2014/05/02/toyota-developing-free-piston-engine-linear-generator-for-hybrid-cars/



Toyota is hot on hydrogen fuel cells for its next-generation cars, but it's not going cold on internal combustion just yet.

The company's R&D division has developed a Free Piston Engine Linear Generator that can convert gasoline and other fuels into electricity more efficiently than existing systems.

It's a technology that could lead to lighter, more efficient, better-packaged powertrains for plug-in hybrid cars.

Instead of connecting a separate generator to the crankcase of an internal combustion engine, the linear generator turns the piston itself into a generator, reducing the overall size and mechanical complexity of the machine.

Opposite the combustion end is a sealed chamber that acts as a gas spring to cycle the piston in lieu of the rotational action of a crank. In this case, a section of the piston is constructed of a magnetic material that interacts with coils in the walls of the chamber to generate electricity.

You can watch an animation of how it works here.

The motor operates on a two-stroke cycle, with intake valves located in the sides of the chamber at the bottom of its travel and an exhaust valve at the end adjacent to the spark plug. Several small units could be grouped together to increase power and cancel out any vibrations.

The German Aerospace Center's Institute of Vehicle Concept unveiled a similar design last year featuring a pair of opposed pistons sharing a combustion chamber, but a Toyota representative tells FoxNews.com that it's design was created internally.

But don't leave hydrogen out of this equation, either. Since it relies on an air spring, the compression ratio of the generator can be adjusted to accommodate just about any combustible fuel.

Toyota has not said when the Free Piston Linear Generator might be ready for production.

[BruceM]

Linear generators aren't new, but it will be interesting to see if it's ever incorporated into an electric car.

The technical problems needing more basic research and development are batteries and hydrogen storage, as well as oil bearing algae production/refining, I think.  Hydrogen is a bear of a fuel due to rapid embrittlement (and then failure) of any metal pipes/tanks carrying it under pressure.  Higher efficiency for electrolysis wouldn't hurt either. 

[glort]

A pulsing engine like that would probably have an output that would make lister flicker seem smooth as a DC supply.   

Like Bruce said, will be interesting to see what happens with it.  There are about 100 of these new and breakthrough technologies announced every year and about every 10 years one of them actually comes to fruition.
As far as engines go, not much new under the sun with them despite the thousands of announcements over the years.  I think the last new design with those was the rotary in the '70s.

Makes me wonder if all these new and revloutionary design press releases have any shred of auntenticity or are just a no cost way for the motor companies to fly the flag and amount to publicity stunts to get some free ink in magazines, journals and websites.

[Ronmar]

There probably wouldn't be any flicker as there would be a power stroke for each cycle.  Where flicker comes into play is that there are several cycles for each power stroke in a 60HZ 4 pole generator powered by a single cylinder...  I would be concerned with vibration anywhere you start throwing mass around without anything to counter it, particularly in a vehicle...

[BruceM]

Agreed, Ronmar, the German linear design mentioned with opposing pistons makes a lot more sense to me than this Toyota prototype. 

[Tom Reed]

Even more interesting, to me anyway, would be an engine with no head and dual opposing pistons. There were some old marine designs that worked this way. They had 2 crankshafts geared together and each crank shaft turned a screw. My thought would be to eliminate the dual cranks and electrically couple the pistons together. Kind of like this but integrated with what Toyota is doing.

[Ronmar]

Fairbanks Morse comes to mind. they were used pretty widely in locomotives and monster pumping stations.  The first ship I was on had 4 of these side by side across the enginroom.  The bottom crankshaft drove an electric generator, the top crankshaft drove the largest roots type blower I have ever seen:)  The 4 generator heads fed a switchboard that distributed the output in one of many possible configurations to 4 propulsion motors. The prop motors were paired up into reduction gearboxes to drive the two shafts.  We had a 5th prop motor coupled to the largest firepump I have ever seen.  But I am getting off topic...

[deeiche]

Looks interesting, eliminates linear motion to rotational loss, plus coupled generator loss.

Down side, appears to be yet another device that depends on rare earth permanent magnets.  Hmmm, where do most of the rare earth deposits reside?

[Ronmar]

I wonder how hard it would be to power and control an excited field winding that is oscillating back and forth:)

[Tom Reed]

Transmit the field power through beryllium copper springs?

[BruceM]

Good possibility, Tom.  I wonder what they are using for linear bearings to support that rare earth confabulation attached to the piston.  Maybe a shaft inside from the compressed air spring end? 

[mike90045]

wild AC converted to DC  like in an Inverter-Generator ?

[Ronmar]

wild AC converted to DC  like in an Inverter-Generator ?

That would be my guess, make the energy as efficiently as possible then massage it to what is required with a smart box...

[cgwymp]

Even more interesting, to me anyway, would be an engine with no head and dual opposing pistons. There were some old marine designs that worked this way. They had 2 crankshafts geared together and each crank shaft turned a screw. My thought would be to eliminate the dual cranks and electrically couple the pistons together. Kind of like this but integrated with what Toyota is doing.

Some also used three cranks:

http://en.wikipedia.org/wiki/Napier_Deltic



Seems like that would smooth out the power!

[Ronmar]

Now THAT would be a really "flat-six"