ever seen an axial engine?
 

Duke Engines – 5 Cylinder 4 Stroke 3 Injector Valveless Axial Engine
seems like a pretty neat idea. and looks like it could be a replacement for a rotary. I guess it is like a rotary without the apex seal problem

Heres the video so people don't have to click

That is awesome. The only problem I can see is changing some of the bearings? PLus they never said anything about RPM's. I wonder what it revs to?

14:1 compression on 91 octane, and the video shows 50 lb-ft at 1500 RPM, looks pretty cool.

no power figures were posted. and I wonder how close it would be for an engine like this to reach a production car. the engine size doesn't seem to be any smaller than a normal 4-banger.

from the looks of it there still are apex seals but used in another location, where the top of the cylinder seals up with all the different ports, it'll need sealing from intake port to compression to ignition etc etc.

also, the cylinder walls move along with the piston in a lateral way, which means if its not in perfect sync, the piston rings will gouge into the cylinder walls.

interesting.

:sweetjesus: 14:1

oh my.... :sweetjesus:

Interesting concept, but if I understand the video correctly not, IMO, useful in current automotive uses, especially doesn't seem like a good "sports" engine. If the cylinders all rotate as the engine revs, I see a very unresponsive engine because of the huge rotating mass.

I do however see its uses with something like the Chevy Volt with its low vibration and most likely a narrow but high power band/efficiency range.

Prototype stage. Even if it were useful, it'll be many many years away from actual commercial deployment.

Pretty sure it has less rotating mass, and in the video as I recall they say it has better throttle response.

There's always some company coming up with the "next" new engine design. And they all end up going nowhere. They always list the "advantages" their engines have but conveniently ignore the disadvantages. Those disadvantages are usually what keep their ideas from going into production as they are too difficult to overcome.

I might have missed it, maybe I need to watch it again. But I still don't see how its less rotating mass as either the cylinders have to rotate around, or the heads have to rotate, or both. Either ways it looks like A LOT of rotating mass. Plus, if the heads have to rotate, how the hell does the fuel get injected as you would have a clusterfuck of hoses and wires that have to rotate with it.

watch the goddamn video first...

The head does not rotate. Nothing rotates except for the crankshaft. The pistons move up and down moving the reciprocater in a wave like motion turing the crankshaft.

The reciprocater weighs less than a crankshaft. They are saying significantly. So thus meaning less rotating mass.

EDIT - And when I said, "wave like motion turning the crankshaft". The duke engine crankshaft is literally a shaft (pole, rod, tube). Not your standard crankshaft from a conventional internal combustion engine.

^ The cylinders are inside a "block". Look at the video and pause it between 2:51-2:53 to see that the pistons are in fact inside a circular block. This block rotates which brings the pistons past the intake & exhaust ports and the spark plug.

Sealing this "block" against the "head" as it rotates is where I see a problem (just like Wankel engines and the apex seal). However, since this engine runs a much higher compression ratio I see big problems trying to keep the rotating "block" and the pistons sealed tightly against the head, especially during the power stroke after ignition.

And how do they achieve variable valve timing? Oh yeah, they can't since there's no valves. It's difficult (near impossible) to meet modern strict emissions regulations on an engine without variable valve timing to allow for optimum cylinder filling at all RPM and load combinations due to changing resonance of the intake tract. This engine completely lacks this ability.

Well if you think I didn't watch the video, can you please explain to me how the engine is delivering its intake charge and exhaust to and from the cylinders?

They specifically said no valves and the cylinders or head move past each from intake to spark to exhaust. It also specifically said 3 sparks for 5 cylinders, if nothing is rotating, can you explain to me how to spark 5 cylinders with 3 sparkplugs.

If you can do that, I'll gladly accept that fail, otherwise, take it back.

I probably have to watch it a few more times, I still don't understand how it can spark 5 cylinders with 3 sparkplugs without something rotating when you have 5 distinct cylinders. Rotaries I understand, this, either I'm understanding it wrong, or I don't understand at all. I've watched it like 3 times already too.

Thanks for that explanation, so I AM right in that something has to rotate.

I didn't see that problem of sealing before, but I understand that more now. I am having a hard time seeing how something that effective rubs against each other (head and cylinder) can hold a seal, much less maintain it over the lifetime of an engine. Rotaries are bad enough already, and the rotor doesn't even rub against the housing.

The pistons are moving in a circle, the intake/spark/exhaust ports are stationary. Think of it linearly, if you simplify this and unroll the circle, it's like having the piston move from cylinder 1 in a block to cylinder 4, depending on where it is in the firing process (vs having everything stay put, and cramming all the stages into each cylinder)

Hence where I said the cylinders are rotating in the engine. The faster the engine revs, the faster the cylinders will have to rotate, hence high rotating mass.

Perhaps I may have worded it badly, but the cylinders will still have to rotate around a center point where a crankshaft would traditionally be. That's my understanding of the engine. Perhaps the cylinders can rotate around slower than what the actual revs are, but the rpms are still linear to engine speed and my understanding of high rotating mass. I'm thinking perhaps a whole 5 cylinders and pistons and all that rotating in a circle, even if it rotates slowly is sure to hold much mass.

the pistons have rotating mass in a regular engine anyways. But this way you remove the cams, cam gears, valves, and probably a decent chunk of the crank weight from the equation, and the moving cylinders look pretty thin/light in comparison.

I think the only way you're going to see one of these engines (Or any other alternative internal combustion engine design) hit the mainstream is if they can dramatically improve thermal efficiency (IE 20% or better) beyond the existing reciprocating engine design (typically around 25-30%).

I don't see that with this axial engine.