New 2-stroke Diesel engine, cool link to Engineering TV
 

Nice description of this new 2-stroke, double opposed boxer layout Diesel engine. I also like piston ports, no camshafts or conventional valves to deal with. With DARPA funding this and DOD interest, it could become a reality in military vehicles. Power to weight and powerplant volume (footprint) looks to be outstanding, if it goes, can you imagine the trickel-down of this design for cars?

Opposed Piston Opposed Cylinder Engine - Engineering TV

Hiya,

It seems to be using something that I've thought would make sense: a "clutch" between the pairs of cylinders, so that you can run off of just two when you don't need all the power of four cylinders.

I wonder if it can be scaled (way) down to have 35-55HP units? [Edit: I guess that they can!]

http://img.photobucket.com/albums/v7...rDiesel-02.png
(click on image for link to very informative video)
http://img.photobucket.com/albums/v7...rDiesel-01.png

This thing looks awesome -- it can be run with just 1 module, or with 2 when you need more power; as each module is fully balanced. It is very efficient --about 40%, and has less heat output.

Very interesting engine design. The piston rods for the outer pistons seemed really long. I wonder if that would cause a problem over time.

That's pretty slick.

Typically long rods decrease loads on compontents, and like he said all of the connecting rods are either always push, or always pull, which would be a big advantage from a wear aspect.

What I'm wondering about is how the outer connecting rods will seal up, and how the outer pistons will wear; more the seal setup than anything, I'm guessing just a big cover over the entire thing . . . .

Kinda reminds me of the spagthorpe (or omega, or whatever they call it)

http://micapeak.com/winona/strange/omega1.gif

Hiya,

Another much more efficient IC engine (~39.5%):

http://www.revetec.com/images/rev_ani.gif
http://www.revetec.com/images/CCE_configurations2.jpg
http://www.revetec.com/images/galima...e_x4v2_042.jpg

This engine design replaces the crankshaft with two counter-rotating cams that have three lobes each -- mainly what this gets you is mechanical torque applied to the output shat at 20 degrees past TDC, which is far earlier than the 60 degrees past TDC that is typical for a conventional IC engine.

These are well into the testing phase, and look to be quite viable.

All things old are new again. The engine described on the Engineering TV link amounts to doubling the old Junkers Jumo or Fairbanks-Morse two stroke diesel engines.

The Junkers Jumo had a good power-to-weight ratio – so much so it was used on high-altitude reconnaissance planes in the 1940s. The Fairbanks-Morse was uber-reliable (there are seventy year old engines still running today making rated power) and would run on anything sorta oily.

The opposed-piston engine gets around one of the major manufacturing problems of the internal combustion engine: the complex cylinder head. The opposed engine simply uses another piston to provide the “equal and opposite” for the piston. I noticed the guy did pay special attention to a known weakness of piston-ported engines – heat buildup in the ports.

I have some reservations.

The Fairbanks-Morse and Junkers Jumo used a gear train to synchronize the motion of the pistons. This engine uses a Scotch yoke mechanism instead. The Scotch yoke is definitely less expensive, especially in the US where so few gear manufacturers survive, but the Scotch yoke is a notoriously weak mechanism that relies on a high-wear connection to the crankshaft. In most applications the Scotch yoke was out of general use before the second World War. Even I am not so old that I can even remember seeing a mass-produced Scotch yoke device. Maybe a Singer sewing machine of the 1950s. Early Singers used a Scotch yoke for the co-ordinated motion of their needle, but sewing machines are hardly high-stress machines.

I have absolutely no idea how you would package this engine in any vehicle other than a sidewheel paddle riverboat. The engine is long and low with the crank in the middle.

Trump card. It is a two-stroke diesel and sooner or later to be mass-produced it would have to meet Tier II emissions requirements. No chance whatsoever. Piston-ported two-strokers are notoriously dirty – emitting scads of unburned hydrocarbons (VOC), particulates, NOx, and carbon monoxide. That’s why they have all but disappeared from the market.

Hi,

Some additional info on the Revetec engine:

Revetec Development page 1
Revetec Development page 2
http://www.revetec.com/images/trilobes2.jpg

I love what he said about the inline four. LOL

also, as a four stroke, the boxer 2 cylinder is as good as it gets. as a two stroke, it is indeed truly balanced. Very clever. The injectors leaving the intake to get just air long before fuel is sloppy, but does keep lube in cylinders for the design. I suppose that is the only engine on earth besides a diesel, that truly benefits from injection.

There are still 2 strokes still being produced where I work. Another thing is diesel exhaust is very easy to clean up. Simple salt water removes over 99% particulate (unburnt hyd.) Many boats are using this to become "Greener" The water based material is not acid because of the reaction with the salt and promotes algae/plant growth as a fertilizer.

Now lets see if anyone is willing to dump a 55 gallon drum of water every 4 hours or so? My father used to run a 2 stroke diesel in the mines, they used them because after cleaning with water the exhaust was less fatal in closed spaces as compared to gasoline emissions. He had to get fresh water every 2-4 hours.

Too bad they won't use the algae cleaners on major coal fired plants to go 0 emissions, not to mention the biodiesel that could be made from such a setup.