How the Duke Engines increases the efficiency of the internal combustion engine

[stevewfl]

Video:

http://pixelbark.com/13045/how-the-duke-engines-increases-the-efficiency-of-the-internal-combustion-engine

[Son of Pappy]

I would like to hear it run!!  I wonder how it will be gyroscopically speaking?

[Rick Hall]

No different than a radial engine in an aeroplane. Once it's spooled up...

In a scooter, different story.... maybe. Depends on how the crank is oriented in the frame.

Cool concept though, very cool.

Rick

[Nosmo]

Actually, very different than an aircraft radial.  Radials have a conventional crankshaft with a single (for a single-row engine or more for multiple rows) crankpin and the conn rods are connected to the master rod knuckle so they all go around at the same time.  (Not to be confused with the original rotary engines that had the crankshaft bolted to the airframe and the whole engine rotated around it.)

http://en.wikipedia.org/wiki/Rotary_engine#Distinction_between_.22rotary.22_and_.22radial.22_engines

This Duke "axial engine" is actually a form of "wobble-plate" engine, the design of which has been around for decades.  Very simple, very powerful for size.

Their difference seems to be that the pistons circle around inside the case, where a regular wobble plate engine, the cylinders/pistons are in fixed bores and just go up and down.

https://www.google.com/#q=wobble+plate+engine

https://www.google.com/#q=dynacam+engine&revid=469752981

[Cuda]

Wonder how it does on emissions ? in todays world very important,
I hope it works out, what they are comming out with today is soooooooo complicated in order to make power , low emissions and economy, very fresh thinking. 

[Rhino]

Top of the "cylinders slide past ports". How is that sealed and how long do the seals last?

[VirginiaJim]

Wonder how it does on emissions ? in todays world very important,
I hope it works out, what they are comming out with today is soooooooo complicated in order to make power , low emissions and economy, very fresh thinking.

Fusion power...quite simple.  Takes one shrimp per vehicle.

[B.D.F.]

Right- what they are calling a 'wobble' plate is a swash plate as used on helicopter rotors, hydraulic pumps, etc.

There are some problems with that design, the first of which is that the port timing is interrelated and not independant from each other as nail valves are. In other words, one cannot control the timing as well but especially not the valve (port in this case) opening rate; a simple fact of life is that mushroom valves open and close very quickly and so spend most of their 'open' time very much open. Ports like this, also used in a Wankle design, are opened and closed at the rate the plate under them can pass by and the rates themselves are fixed. The second problem is that there must be some type of sliding plate, or metal seal above each piston; this is fine for intake but suffers on the exhaust stroke where there is zero lubricant on that seal. Again, a common problem that is shared with the Wankle and shows up as short seal life, and excessive oil consumption.

There really are sound physical reasons why a mushroom valved, reciprocating piston engine has been chosen as the powerplant of choice. Others certainly have specific benefits (two cycle engines are simpler and rev. higher, Wankles have an extremely high power to weight ratio, etc.) but in the end, the best overall performing engine is the one that goes back over two centuries. I know a lot of people think it is a conspiracy by someone / some entity, or that that really clever guy has not come along yet but physics really does rule the day here and what we have is about as good as it is likely to get for internal combustion engines.

Brian

Actually, very different than an aircraft radial.  Radials have a conventional crankshaft with a single (for a single-row engine or more for multiple rows) crankpin and the conn rods are connected to the master rod knuckle so they all go around at the same time.  (Not to be confused with the original rotary engines that had the crankshaft bolted to the airframe and the whole engine rotated around it.)

http://en.wikipedia.org/wiki/Rotary_engine#Distinction_between_.22rotary.22_and_.22radial.22_engines

This Duke "axial engine" is actually a form of "wobble-plate" engine, the design of which has been around for decades.  Very simple, very powerful for size.

Their difference seems to be that the pistons circle around inside the case, where a regular wobble plate engine, the cylinders/pistons are in fixed bores and just go up and down.

https://www.google.com/#q=wobble+plate+engine

https://www.google.com/#q=dynacam+engine&revid=469752981

[B.D.F.]

The simple way is nothing but very close metal fit between the cylinder and the outer shell that the ports are in (the video does not really show that intermediate part). A better way is a metal or ceramic ring, spring loaded to bear against the outer shell and fit into a groove in the inner, rotating member. Either way, lifespan will not be long due to the inability of that seal being able to carry any lubrication past the exhaust and power portions of the cycle.

Brian

Top of the "cylinders slide past ports". How is that sealed and how long do the seals last?

[Two Skies]

Turns out they have a website, with a FAQ.

From the FAQ:
http://www.dukeengines.com/technology/faq/#type

WHAT ABOUT SEALS?
The Duke sliding seal arrangement is analogous in function to a ported 2-stroke or Wankel engine port sealing, allowing similar technologies to be applied.  The Duke uses sliding metallic seals operating on an oil film. Materials used are those found in production road vehicles.  The V3i engine has seals which are of a simple design and operate at modest contact stress and sliding velocities. Oil film calculations conducted support good nominal lubricating film thickness.

All V3i gasoline and Jet A1 testing to date (March 2012) has been completed with a single set of prototype seals which remain in good condition.  These seals will be reassembled into an engine for further testing without modification or repair.

Duke challenges in seal development are much less than in a 2-stroke or in the Wankel engine due to lower sliding velocity and a flat monoplane sealing surface (Wankel has 3 seal faces, 1 curved, that meet at a corner, seals).  So far, our sliding seal challenges are proving to be modest in reality.

The valveless porting comment is also interesting.  Essentially the 3 intake and exhaust ports are always open.  Not having to divert horsepower to the valve train should mean an increase in overall power output, IF they can control the mixture adequately.  They seem to think they can. 

The other question will be if it can pass emissions standards.  One of the reasons compressions were lowered in current gasoline powered vehicles (as I understand - premature detonation is another reason) was because of the complex molecule chains that are produced/emitted by gasoline engines at higher compressions.  Otherwise, we'd have higher compression gasoline powered domestic vehicles today.  More compression generally means more horsepower, which is why the 60's era muscle cars are more powerful than some of their later counterparts.

Duke is claiming a 14 to 1 compression ratio using gasoline with no detonation in the video.  The FAQ notes that a variety of fuels could be used.  I'd be interested to see their emissions numbers.

[Two Skies]

Also, here's a fun link about axial internal combustion engines (also known as barrel engines):
http://www.douglas-self.com/MUSEUM/POWER/unusualICeng/axial-ICeng/axial-IC.htm

[ManofManyGTs]

Cool. Here it is running I think: Low vibration engine with lighter weight