Sealing in Ricardo's sleeve valve engines 3

[THT]

These engines keep bothering me.

Was the lube oil consumption outrageous in modern terms? Would any modern fluids or materials or designs help there, if you were to implement something like that today?

How was the port sealing (for gasses, as well as and oil) done? I don't have access to details, what's online doesn't tell much.

Was it a good design, if you compare it to today's poppet valve engines (with multiple valves and adjustable valve timings and whatnot)? I mean, did the sleeve valve offer any inherent benefits, and how much of a drawback is the radial (side) rather than axial (head) flow? If the engine has charging?

 

[romke]

I am not familiar withe the sleeve valve type of engine used in aircraft. The sleeve valve engine also was extensively used in expensive motorcars in the past, based on a patent of the original designer C.Y.Knight. It not only was fitted in Knight cars, but also in at the time famous marques like Cadillac, Mercedes, Voisin and Minerva. The good thing about these engines was that they were relatively quiet compared to engines with poppet valves. Unfortunately the design did not allow high rpm, so when designers tried to get more power from a given cylinder size, they disappeared because the actuating mechanism of the sleeves (the "ears") usually broke off quite rapidly, calling for costly repairs.

Oilconsumption in modern times sure was not good, but in those days they were no worse then poppet valve designs that needed decoking quite often whereas the sleeve engine could attain a much higher mileage before needing service.

 

[Lou Scannon]

Here is an interesting paper, not focused on sealing per se, but a broad competitive analysis of sleeve valve vs poppet valve aircraft engines.
Many other interesting topics at this site as well.
The sleeve valve breathing characteristics are actually quite good, due to ability to change the valve area between zero and max quite quickly. Other than its late start (at least in the cutting edge aero realm) relative to the poppet valve, drawbacks were higher thermal resistance between the inner liner and the heat sink (i.e. cooling fins or water jacket), and as in a piston ported 2-stroke, issues related to the piston rings running across the ports every stroke.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

 

[tbuelna]

The debate regarding the relative merits of sleeve valves versus poppet valves has been going on for over half a century. Here's all you need to know about the subject- Every engine designer knows all about sleeve valves, as does every engine manufacturer. These people are not stupid. So if sleeve valves were so much better than poppet valves, all modern IC piston engines would be using sleeve valves. But none of them use sleeve valves, and most of them use poppet valves. So what does that tell you?

 

[djhurayt]

Tells me that maybe, possibly, we as designer/engineers have missed some un-realized advantages . . ., after all the world was flat and that was once fact, till some guy named Chris came along.

 

[PackardV8]

Also worthy of discussion is today's machining controls and quality control are 100 years advanced from the day of the sleeve valve. If a sleeve valve engine were designed and built today, with synthetic lubricants, it would be more efficient, last longer, make more power and still not be competitive with poppet valve designs.

jack vines

 

[gruntguru]

Sleeve valve engines have already proven to be competitive - and proven to be superior - in certain metrics and in certain applications.

Can they compete against poppet valve engines in the automotive, small engine or light aviation sectors? No.

je suis charlie

 

[dicer]

All gasoline 2 strokes use sleeve valve principles. The piston skirt is the valve.

https://www.youtube.com/watch?v=qrkqL3sBogA

The main reason for not using sleeve valve is number one they cost a lot more to manufacture. Number two is lubrication is difficult. And I agree it is a much better system and more durable. In this day of disposable engines, cars etc. there is no need for durability.

 

[THT]

Thank you folks for great replies. As I see it now, a sleeve valve engine wouldn't have the efficiency (or intentional inefficiency for emissions control) of a poppet valve four-stroker, the simplicity of a two-strokers for small engines, nor the reliability for aircraft engines. Engineers have never been stupid, and they take great care whose shoulders they tap-dance on. No problem there.

Going off on a tangent now, I too detest the day of disposable engines. I've seen a referral of a study on the production energy costs of a small modern car (with its engine). Made it look like it's better to keep the old stuff running and not fill the landfills to the brim with this not particularly organic stuff.

But I didn't quite get a detailed answer on the sealing question. I'm sure (from some sources) that oil consumption was higher, but what was mechanically done to seal it? (And port gases.) Some kind of metal spring arrangement, something like piston rings, or just pressure differential sealing?

 

[THT]

Alright, the paper hemi linked addresses my questions. Shouldn't have just skimmed it before.

I still can't help thinking of a sleeve valve system in the context of a modern charged direct-injected diesel. In a naive version, no need for intake port swirl if the piston shaping handles it. More boost if there's no head and head gasket. Better combustion temperature control when needed if the head is just flat and dumb.

Obviously it isn't so simple, but it's a useful jumping (off) point for further studies on the highly empirical art of engineering.

(Bear with me. I'll have a high read:write ratio...)

 

[tbuelna]

...More boost if there's no head and head gasket. Better combustion temperature control when needed if the head is just flat and dumb....

4-stroke sleeve valve engines still have heads and head gaskets. The head "gaskets" are just piston rings. The cylinder heads of conventional 4-stroke poppet valve DI diesel engines are also flat, and the combustion chamber is part of the piston crown. One of the largest sources of friction loss in a high-pressure diesel engine are the piston rings. So doubling the number of piston rings required in a 4-stroke sleeve valve engine would not be good for efficiency. One significant limit with high-pressure diesel engines is heat transfer from the piston rings across the cylinder wall. The heat transfer situation with the added sleeve valve thickness is far worse. Lastly, how would a thin wall, large diameter sleeve valve handle combustion pressures of 2500psi or more?

 

[PackardV8]

In this day of disposable engines,. . there is no need for durability.

I too detest the day of disposable engines.

Sorry, but I just don't understand the above. Those of us in the rebuilding industry now see engines running 3X the miles/km and being in better shape at teardown. With a few exceptions, today's engines (and cars) are built to a much higher standard in and will last many times longer/farther than anything built back in the day.

Yes, I was there then too and rebuild obsolete engines today. Carburetors, distributors and leaded gas are the devil's devices and killed engines long before their natural death.

Today, we can take a '70s big block Ford or GM V8, rebuild with today's QC and parts, add EFI/computer control and it will run at full torque 3X as many hours as it did in its first life.

jack vines

 

[BigClive]

I don't see that a sleeve valve engine has "better breathing". Most engines today can achieve over 90% VE and with inertial effects etc. well over 100% VE. Is the sleeve valve likely to be better than this? Unlikely.

 

[dicer]

PackardV8, where is the market for rebuilt automobile engines nowadays? Most people just are not going to spend the $2000 to $3000 for a rebuilt engine for a car that is worth as much. Maybe for warranty issues on some vehicles. It just seems more people would just rather purchase a new car than put more money into something that will not have enough value to recover the costs or a few months later need a rebuilt transmission, or suspension, paint job etc. Some cars are just not worth the effort newish or old.

 

[gruntguru]

"4-stroke sleeve valve engines still have heads and head gaskets. The head "gaskets" are just piston rings. The cylinder heads of conventional 4-stroke poppet valve DI diesel engines are also flat, and the combustion chamber is part of the piston crown. One of the largest sources of friction loss in a high-pressure diesel engine are the piston rings. So doubling the number of piston rings required in a 4-stroke sleeve valve engine would not be good for efficiency. One significant limit with high-pressure diesel engines is heat transfer from the piston rings across the cylinder wall. The heat transfer situation with the added sleeve valve thickness is far worse. Lastly, how would a thin wall, large diameter sleeve valve handle combustion pressures of 2500psi or more?"
- I think one extra ring is typical.
- The extra ring has far less travel and rubbing speed, therefore less friction.
- I believe heat transfer is not an issue. The sleeve "grows" and the clearance decreases until delta T, heat flux and thermal resistance match up.
- The thin wall sleeve is also supported by the cylinder it runs in (via the oil film - even the full 2,500 psi is low for an oil film)

je suis charlie

 

[tbuelna]

The Bristol 4-strokes used at least two rings on the junk head.

http://www.enginehistory.org/G&jJBrossett/Coventry/Bristol Hercules sleeve down.JPG

The junk head rings had far worse lube oil conditions than the piston rings.

The junk head rings were subjected to the same combustion pressure forces as the piston rings. The sliding frictions they produced on the sleeve valve were continuous during operation since the sleeve valve never stopped moving. Poppet valves on the other hand don't produce friction losses when they are closed/seated.

 

[j2bprometheus]

Here are some references on sleeve valve engines:

White, Graham. Allied Aircraft Piston Engines of World War II: History and Development of Frontline Aircraft Piston Engines Produced by Great Britain and the United States. Society of Automotive Engineers, 1995. ISBN: 9781560916550

Setright, L.J.K. Some Unusual Engines, Mechanical Engineering Publications. 1975. ISBN 0-85298-208-9.

Ricardo, Harry High Speed Internal Combustion Engines (out of print -- but their are paperback reprints available on the web.

Hunter , Marcus C. Inman. Rotary Valve Engines, John Wiley and Sons, 1946. This has a section on sleeve valve engines.


RICARDO consulting probably published some other sleeve valve info. They had proposed a sleeve valve diesel for light aircraft 10 or 15 years ago.

j2bprometheus

 

[Overrun]

The sleeve valve push goes back to WW2 and Ricardo’s calculations that poppet exhaust valves would overheat with increasing engine displacement/boost. He saw the sleeve valve as the better course for this problem. It instead developed that the sodium-filled exhaust valve scaled up just fine.

Given that Ricardo did the early work in squish to control knock in side valve engines, it’s too bad that he got sidetracked since the big hemi aero engine could likely have gained from a faster fuel burn

 

[tbuelna]

There were lots of IC engine issues that needed to be solved back in the mid 20th century. Ricardo's work addressed some of the most fundamental problems concerning combustion. The sleeve valve was a solution to limitations of poppet valve technology at the time, but since then poppet valve technology rapidly improved to the point where it now far outperforms sleeve valves when all factors are considered.

The brilliance of Ricardo's research was the influence of chamber geometry and charge motion on combustion efficiency.

 

[140Airpower]

"djhurayt (Mechanical)2 Dec 15 13:02
Tells me that maybe, possibly, we as designer/engineers have missed some un-realized advantages . . ., after all the world was flat and that was once fact, till some guy named Chris came along."

Chris? Who he? Johnny-Come-Lately, about 1,800 years late. The Greeks measured the size of a spherical Earth with an error on the order of 1% (by some interpretations of their system of measures). In fact, if Chris knew what the ancient Greeks knew about the size of the Earth and not knowing there were unimagined continents in his way, he might have figured it was too big for him to make the journey with the resources he had.

About WWII style sleeve valves:
It seemed the sleeve mechanism was more rpm-limited than pushrod poppet valves.
Single sleeves sealed extremely well since they totally encompassed the cylinder pressures and expanded against the fixed cylinder wall. This contrasts with other forms of rotary valve settups.
Sleeve valves needed much less oil than conventional 4-strokes because since the sleeve was constantly moving, the rings never stopped against the sleeve with no stiction problem as occurs in conventional engines especially at the top of the stroke where the top ring runs dry.
Also, the sleeve's motion distributes the oil film much better than what happens in the conventional engine.
Initially, the sleeve valve held about a 20% greater CR tolerance than poppet valves due to the hot exhaust valve. But, sodium cooling reduced that advantage.
The sleeve valve required better manufacturing precision making it a more expensive engine. Today that probably would not be a problem.
The piston ran hotter in the sleeve valve engine due to a somewhat less direct path to cooling.