[Rune]

DLR team develops demonstrator of free-piston linear generator as range extender for EVs; technology transfer to Universal Motor Corp.
20 February 2013

Researchers at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) Institute of Vehicle Concepts in Stuttgart have developed a demonstrator multi-fuel free-piston linear generator (FPLG, or Freikolbenlineargenerator, FKLG in German) as a range extender for electric vehicles. The FPLG comprises an internal combustion component, a linear generator and a gas spring; the researchers have demonstrated the feasibility of the technology on a test bench specifically developed for this purpose.

The free-piston linear generator works in a similar manner to a conventional combustion engine, but instead of converting the linear movement of the piston into the rotational movement of the crankshaft, it generates electricity directly. A fuel-air mix is ignited in the combustion chamber. This expands and pushes the piston towards the gas springs. These springs decelerate the piston movement and push it back. The linear generator converts the kinetic energy of the piston into electricity and this in turn powers the electric motor.

Not as powerful as the OPOC - about 40 hp - but would be great for small electric cars. It would act as a range extender and would be small and lightweight.

I don't understand why these things are not being done already. It is not as if this is rocket science. The bugs they are ironing out don't seem to be big bugs at all.

[vision-master]

The linear generator converts the kinetic energy of the piston into electricity and this in turn powers the electric motor

How is this energy converted?

[rollin]

Let me break this terrible news to you gently, Rollin...

I'm very sorry, but you're never going to get 375 hp out of solar car.

Nothing to do with my post so I guess your trolling again or just off in the ozone layer with the Mars squad.

[Rune]

Let me break this terrible news to you gently, Rollin...

I'm very sorry, but you're never going to get 375 hp out of solar car.

Nothing to do with my post so I guess your trolling again or just off in the ozone layer with the Mars squad.

I read about it. The Stella is a solar car. You don't get much power from a small array of solar panels. Solar energy is so diffuse that it is impressive that the car was able to traverse 3000 miles of straight flat highway in one of the sunniest climes in the world.

Try hauling a flatbed full of pig iron up a cloudy mountain in a solar truck. Ain't gonna happen, my thermodynamically impoverished friend.

[Rune]

The linear generator converts the kinetic energy of the piston into electricity and this in turn powers the electric motor

How is this energy converted?

The opposing pistons thrust a magnet back and forth linearly through an electric field and generate an alternating current, whose frequency then has to be regulated and converted to dc to charge the battery.

[vision-master]

No crankshaft, just some kind of gas springy thingy?

[Rune]

No crankshaft, just some kind of gas springy thingy?

Jus' some kina gas springy thingy.

[Keith_McClary]

The linear generator converts the kinetic energy of the piston into electricity and this in turn powers the electric motor

How is this energy converted?

Like
these

I guess.

[rollin]

I read about it. The Stella is a solar car. You don't get much power from a small array of solar panels. Solar energy is so diffuse that it is impressive that the car was able to traverse 3000 miles of straight flat highway in one of the sunniest climes in the world.

Try hauling a flatbed full of pig iron up a cloudy mountain in a solar truck. Ain't gonna happen, my thermodynamically impoverished friend.

Cars and tractor trailers are different. The car is just to move a butt around and some light cargo. Tractor trailers move small loads of freight over public built and subsidized roads.
Now real loads,that's what railroads are for. Those 12000 hp Chinese electrics wouldn't even feel that small load of pig iron, they carry more ballast than that.
PV, wind and hydro can run all that freight without ICE.

[Rune]

Not tomorrow, it won't.

At any rate, this is an a much-improved internal combustion engine that increases efficiency 30%. It packs a whallop of horsepower in a very small volume.

The OPOC design is elegant. It will be rolling off Chinese assembly lines in 3 or 4 different regional factories beginning next year.

Navistar International, a huge truck manufacturer, is designing a whole new Class 8 transport around this motor.

The US Army is far along in testing it for battlefield use.

Many who have described it in articles and features call it a "game-changing" ICE innovation.

Apparently, we won't see a smaller enine for personal vehicles for a while. But, this motor creates all sorts of design flexibility. You could design a car with two of them under the hood - one for city driving, the other one kicking in for higher hp requirements. That's great!

If the mileage actually does come close or break the 100 mpg range, then a hybrid version would create a car getting 150 - 200 mpg potentially. And since this motor is so small, it leaves space for the battery and increases the utility of hybrid cars.

These are all very, very good things.

[Keith_McClary]

Alternate ICE designs sometimes take a few iterations to get right.

[Keith_McClary]

The engines being built in China are for generators and large trucks.

The US Army has a contract with EcoMotors for use in large vehicles.

Will these be Made in China?

[Rune]

The engines being built in China are for generators and large trucks.

The US Army has a contract with EcoMotors for use in large vehicles.

Will these be Made in China?

Good question. I don't know.

The army has prototypes of the EcoMotors OPOC Turbo Diesel which has something like 480 hp. They are testing it. But I imagine that EcoMotors itself made them. If the Army requested thousands of them, I don'lt know who would be awarded the contract. Probably GM.

[BigRed17]

I have been doing research on this subject for a while now and I am wondering what anybody's thoughts are on this. What if they were to make the outer pistons double sided and add a cylinder head on the outside? It would add more parts (spark plugs, intake, etc.), but imagine the increase of power and speed it would add. It would be an engine with 2 cylinders, 4 pistons, and 4 combustion chambers. Extremely efficient and compact.

[Scrub Puller]

Yair . . . I will believe this technology when the first one has ten thousand hours on the clock . . . and Keith_Mclary even though the odd manufacturer put the horrible Wankel concept into production I can assure you they didn't get it "right"

Cheers.

[Keith_McClary]

I have been doing research on this subject for a while now and I am wondering what anybody's thoughts are on this. What if they were to make the outer pistons double sided and add a cylinder head on the outside? It would add more parts (spark plugs, intake, etc.), but imagine the increase of power and speed it would add. It would be an engine with 2 cylinders, 4 pistons, and 4 combustion chambers. Extremely efficient and compact.

http://www.greencarcongress.com/2013/02 ... 20220.html
Wouldn't it be 3 combustion chambers? And not very compact, unless you're thinking of the shaft going thru the combustion chambers.

[Keith_McClary]

Keith_Mclary even though the odd manufacturer put the horrible Wankel concept into production I can assure you they didn't get it "right"

That was sorta my point. When I read about whiz-bang technologies today, I always think about past technologies they could never get right.

[BigRed17]

I was thinking more like the outer pistons with the longest connecting rods have a piston head on the other side, so it would add another combustion chamber on each outside edge of the piston against 2 outside cylinder heads, similar to what engines look like now. The ignition and power stroke would drive the pistons back inwards towards the inner pistons with more power.

[Keith_McClary]

http://www.dukeengines.com/

"Duke Engines demonstrate a new kind of internal combustion engine, based on a crazy, hypnotic, rotary system. I lack the mechanical engineering chops to know whether this is any good, but it's fun to watch."
http://boingboing.net/2014/07/15/new-ki ... ne-hy.html

[Tanada]

I was hoping to find out things were progressing on these engines so we could get some real world data. Unfortunately the company website is two years out of date and the only news story I found since then is the following one. The author is a motor cycle enthusiast who wants to see the engine used for that application.

http://www.motorcyclistonline.com/duke- ... torcyclist