Coates Spherical Rotary Valve - why hasn't anyone produced these large scale?

[NAKID]

[Mother]

In the video on their website they reckon oil contamination is not an issue as it is completely sealed(?)

really?

just looking at that thing makes me think otherwise

but

if you were burning ethenol...

[bigiain]

A single rotor would have 2, but Mazda typically builds 2 or 3 rotor Wankels. The rotor (2 or 3 of them) and a crank..

And then there's those 3 tip seals per rotor, and 6 side seals... Worse than bloody piston rings in my experience.

big

[junior varsity]

I don't see a port for water injection to further boost engine efficiency, so unless it runs on the power of my farts, what we have now for gas engines is perfectly fine.

Its neat, but in a 'gas crunch' I don't think slight boosts in fuel efficiency are where engineering time should be spent by the major manufacturers for production vehicles.

For racing applications, it looks nifty, but also really difficult to rebuild if something goes bad, etc....

[Ash]

Well, it could never be an interference engine, so you'd have that going for you...

i think that's the key...

compression ratio would be limited, or piston dome shape would be limited, or both (more likely).

kind of not what you want in a racing engine...

[TiAvenger]

And then there's those 3 tip seals per rotor, and 6 side seals... Worse than bloody piston rings in my experience.

big

muhahaha, the dreaded 80k apex seal replacement.............

[monsterduc]

i think that's the key...

compression ratio would be limited, or piston dome shape would be limited, or both (more likely).

kind of not what you want in a racing engine...

From their website:
"Some of the Coates Spherical Rotary Combustion Engines are at 12 to 1, 13 to 1, 14 to 1 and 15 to 1 compression ratios depending on the application"

and
"For instance: a static test of a five-litre poppet valve engine on an airflow machine produced a reading of 133 cubic feet per minute (CFM) with valve fully opened. The five-litre Coates Spherical Rotary Valve Engine on the same machine, however, produced a reading of 319 CFMs fully opened; a colossal advantage in airflow comparison. A five-litre poppet vavle engine tested on a dynomometer under the same loads and conditions at 5500 produced 480 BHP and 454 foot pounds of torque. The maximum RPMs on the poppet valve engine were 5700 RPMs; the Spherical Rotary Valve Engine in comparison reached 14,850 RPM's, "

The only thing that strikes me as questionable is that last sentence where they say they revved a 5 liter engine to 14,850 rpm.  I thought one of the factors limiting rpm, besides valve float, is piston speed.  Assuming that engine was a V8 (mentioned earlier in the article was a Lincoln engine), it seems hard to imagine the large pistons in a 5 liter V8 moving that fast.  

[NeufUnSix]

I call BS, the rods and crank would obliterate themselves at those RPMs on a large displacement motor. Hell, Ducati 996s had trouble with the con rods at sustain high revs, and those hit about 10500.

[Grampa]

Dave said "wankle"


tee hee   

[Mother]

I call BS, the rods and crank would obliterate themselves at those RPMs on a large displacement motor. Hell, Ducati 996s had trouble with the con rods at sustain high revs, and those hit about 10500.

why?

Indy cars can hit 20,000 rpm

[acalles]

Coates stated, "The spherical rotary valve system provides such substantial benefits that this system has the potential to integrate within and revolutionize engine manufacturing and design. The Company's facility has already been visited by and hosted tours to the major manufacturers, and dialogue regarding the use of the technology is ongoing. Coates went on to say, "The major advantages of the Coates design include: Substantially lower CO carbon monoxide, HC hydrocarbon and NOX oxides of nitrogen emissions, Increased engine efficiency, Use of lower octane fuel, Elimination of oil from engine valves, Reduced lubrication and maintenance requirements, Reduced manufacturing costs, Reduced fuel consumption"

none of this makes sense in any possible way. Fuel trim and cyl head flow are two different things..

cyl head looks cool, but if it worked, don't you think some one would be using it. I've honestly never seen one running and I read about this years ago when I went to UTI...

they also read a bit on desmodromic valves.. since I read that, I had to own something with them 

[mitt]

Probably the same reason engineers at honda/ford/gm/vw/nissan don't use these:

   



mitt

[Rameses]

i think that's the key...

compression ratio would be limited, or piston dome shape would be limited, or both (more likely).

kind of not what you want in a racing engine...

No, he was saying that it wouldn't be possible to build an interference engine since there would never be any valves protruding into the combustion chamber.

It would still be possible to design ultra-high compression ratios.

[Punx Clever]

...
The only thing that strikes me as questionable is that last sentence where they say they revved a 5 liter engine to 14,850 rpm.  I thought one of the factors limiting rpm, besides valve float, is piston speed.  Assuming that engine was a V8 (mentioned earlier in the article was a Lincoln engine), it seems hard to imagine the large pistons in a 5 liter V8 moving that fast.   

Large bore / short stroke.  Shorter the stroke, lower the piston speed.  Increase the bore to counteract the loss of displacement.  Just a hunch.

As for why the system wouldn't be used...  Those valves are constantly spinning and have interruptions (see hole) on the surface that contacts the seals.  Biggest problem I see with the valve design is seal life.

[Speedbag]

if that thing is exposed to the combustion chamber as it spins around

the deposits on the face of the valve will create issues in long term applications on production vehicles

+1

Seems to me this issue is the key as far as it not being used widely in normal passenger vehicles. I remember (barely) reading an SAE paper a long time ago on them.