Sleeve Valves?
Started by
hydra
, Mar 26 2004 15:19
11 replies to this topic
#1
hydra
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Posted 26 March 2004 - 15:19
Just finished reading Ricardo's High-Speed Internal Combustion Engines. Great book, but you probably didn't need me to tell you that... What I want to know is, since sleeve valves were shown to be superior to poppet valves in pretty much every single way, and were used on many high-rpm, high bmep military applications with almost flawless reliablity over 60 years ago, what prevents their use now?
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#2
McGuire
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Posted 26 March 2004 - 16:18
Originally posted by hydra
Just finished reading Ricardo's High-Speed Internal Combustion Engines. Great book, but you probably didn't need me to tell you that... What I want to know is, since sleeve valves were shown to be superior to poppet valves in pretty much every single way, and were used on many high-rpm, high bmep military applications with almost flawless reliablity over 60 years ago, what prevents their use now?
Improved metallurgy and processes have since handed the clear advantage over to the poppet valve. While there were some magnificent sleeve valve aero engines, I'm not sure we can say they were truly head and shoulders superior. The sleeve valve benefitted greatly from the low and narrow rpm range of aircraft piston engines: constant load, under 5000 rpm. When its role in aircraft was obsoleted by the jet turbine, the sleeve valve found the end of the road. Its viability in high-speed automotive engines is highly doubtful: in a nutshell, excessive reciprocating weight.
#3
dovatf
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Posted 07 April 2004 - 20:46
There's also a lot of info about single sleeve valves engine in Arthur W. Judge "Aircraft engines" book. You will also find some information in several more books listed here, along with some interesting bits:
http://www.a-car.com...ves/sleeve.html
I'm not convinced that "improved metallurgy and processes have since handed the clear advantage over to the poppet valve", for the reason that such improvements would have also benefited to the sleeve valve engines.
In Judge's book there's the BMEP and power curves of the Bristol Perseus against the ones of the same engine but with 4 poppet valves per cylinder, the Mercury. The torque and power of the Perseus was much better over the whole rev range - which the graph unfortunately shows from 2000 to 3000 rpm only.
As the stroke of the sleeve was half of the piston stroke and since the sleeve drive mechanism was rotating at half crankshaft speed, the reciprocating weight of the sleeves was not a problem. With its 177.8 mm of stroke, the Bristol Centaurus had a MPS of 16 m/s at 2700 rpm. The Napier Sabre had a nominal speed of 3850 rpm with a stroke of 120 mm.
The advantages of the sleeve valve engines were numerous.
1. Suppression of the hot spot of the exhaust valve enabled 8 to 15% higher compression ratio.
2. Better volumetric efficiency and power
3. Better combustion chamber shape
4. Lower SFC
5. Lower head and piston operating temperatures
6. Reduced maintenance attention
7. Greater simplicity due to fewer parts, absence of oil ducts to the cylinder heads
8. Less operating noise
9. Reduced production cost (stated by Judge, but I'm not sure about that)
10. Superior reliability
There were few problems and drawbacks:
1. The required cranking power was higher
2. Special attention to cylinders cooling and lubrication had to be paid
3. The sleeve had to be made in a nitrided chrome-nickel alloy (KE965) which is said to have about the same thermal expansion coefficient than the aluminum alloy.
The only problem I can see which would prevent the production of automotive single sleeve valve engines nowadays is the exhaust toxic emissions due to unavoidable excessive amount of lubricating oil that would infiltrate into the combustion chambers. At the time the oil consumption of poppet valve engines and sleeve valve engines was the same, but today a sleeve valve engine could not meet emissions standards.
I think it is just because of the conservative nature of the automotive OEMs that none of them took up the concept after the WW II. Most of them were still producing side valve engines ; overhead valves and camshafts were a refinement reserved for expensive sport cars. Furthermore, the sleeve valve technology was mastered by a few British aircraft engine producers only, namely Bristol, Napier and Rolls-Royce, which made some prototypes of an H24 engine similar to the Sabre but bigger, the Eagle of 46 liters displacement and 3400 hp.
Production of sleeve valve automotive engines would have required further R&D and it is understandable that none was willing to undertake such a task, which would have led to an unknown foreign territory.
http://www.a-car.com...ves/sleeve.html
I'm not convinced that "improved metallurgy and processes have since handed the clear advantage over to the poppet valve", for the reason that such improvements would have also benefited to the sleeve valve engines.
In Judge's book there's the BMEP and power curves of the Bristol Perseus against the ones of the same engine but with 4 poppet valves per cylinder, the Mercury. The torque and power of the Perseus was much better over the whole rev range - which the graph unfortunately shows from 2000 to 3000 rpm only.
As the stroke of the sleeve was half of the piston stroke and since the sleeve drive mechanism was rotating at half crankshaft speed, the reciprocating weight of the sleeves was not a problem. With its 177.8 mm of stroke, the Bristol Centaurus had a MPS of 16 m/s at 2700 rpm. The Napier Sabre had a nominal speed of 3850 rpm with a stroke of 120 mm.
The advantages of the sleeve valve engines were numerous.
1. Suppression of the hot spot of the exhaust valve enabled 8 to 15% higher compression ratio.
2. Better volumetric efficiency and power
3. Better combustion chamber shape
4. Lower SFC
5. Lower head and piston operating temperatures
6. Reduced maintenance attention
7. Greater simplicity due to fewer parts, absence of oil ducts to the cylinder heads
8. Less operating noise
9. Reduced production cost (stated by Judge, but I'm not sure about that)
10. Superior reliability
There were few problems and drawbacks:
1. The required cranking power was higher
2. Special attention to cylinders cooling and lubrication had to be paid
3. The sleeve had to be made in a nitrided chrome-nickel alloy (KE965) which is said to have about the same thermal expansion coefficient than the aluminum alloy.
The only problem I can see which would prevent the production of automotive single sleeve valve engines nowadays is the exhaust toxic emissions due to unavoidable excessive amount of lubricating oil that would infiltrate into the combustion chambers. At the time the oil consumption of poppet valve engines and sleeve valve engines was the same, but today a sleeve valve engine could not meet emissions standards.
I think it is just because of the conservative nature of the automotive OEMs that none of them took up the concept after the WW II. Most of them were still producing side valve engines ; overhead valves and camshafts were a refinement reserved for expensive sport cars. Furthermore, the sleeve valve technology was mastered by a few British aircraft engine producers only, namely Bristol, Napier and Rolls-Royce, which made some prototypes of an H24 engine similar to the Sabre but bigger, the Eagle of 46 liters displacement and 3400 hp.
Production of sleeve valve automotive engines would have required further R&D and it is understandable that none was willing to undertake such a task, which would have led to an unknown foreign territory.
#4
McGuire
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Posted 07 April 2004 - 21:25
I'll stand behind my previous statement. Please understand I have nothing against sleeve valves. I'm a big fan of the Knight engine, having owned and rebuilt several. The engine in my 1929 Willys-Knight was superior to those in many 1929 automobiles, but inferior in every way to a 1958 anything. Meanwhile, no application of 21st century technology can correct its inherent shortcomings.
You write: "I'm not convinced that "improved metallurgy and processes have since handed the clear advantage over to the poppet valve", for the reason that such improvements would have also benefited to the sleeve valve engines." That rather assumes the advances would have benefited both engines equally, when there are some problems technology can't overcome.
It's interesting that this thread should resurface now. Just yesterday I saw a reference to sleeve valves in the latest issue of Race Engine Technology. Paul Jette of Del West Engineering: "I have heard of people working on sleeve valves. If you look at the different valve mechanisms that have been in existence since the early days you will find numerous solutions. It is not that the other ideas don't work. They can all be made to work. But it is very difficult to find something that exceeds the capablities of what we have now."
That seems to me a very good way to sum things up. We tend to look back at intriguing ideas from the past and say "Hmm, why not?" when we should be taking the hard look and asking ourselves "Why?"
You write: "I'm not convinced that "improved metallurgy and processes have since handed the clear advantage over to the poppet valve", for the reason that such improvements would have also benefited to the sleeve valve engines." That rather assumes the advances would have benefited both engines equally, when there are some problems technology can't overcome.
It's interesting that this thread should resurface now. Just yesterday I saw a reference to sleeve valves in the latest issue of Race Engine Technology. Paul Jette of Del West Engineering: "I have heard of people working on sleeve valves. If you look at the different valve mechanisms that have been in existence since the early days you will find numerous solutions. It is not that the other ideas don't work. They can all be made to work. But it is very difficult to find something that exceeds the capablities of what we have now."
That seems to me a very good way to sum things up. We tend to look back at intriguing ideas from the past and say "Hmm, why not?" when we should be taking the hard look and asking ourselves "Why?"
#5
dovatf
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Posted 07 April 2004 - 22:27
I have nothing neither against poppet valves, valvetrains and head gaskets… as long as they don't give any trouble.
For those who may ignore it, it must be said that the Knight was a double sleeve engine, which was much inferior to Burt-Mc Collum single sleeve engines.
Of course, a modern poppet valves engine is superior to a WW II era sleeve valve engine! It's hard to know which one would be the best if both concepts had concurrently been developed till nowadays. But we know that the last sleeve valve engines such as the Bristol Centaurus, RR Eagle and the late versions of the Bristol Hercules proved superior to similar poppet valve engines of their time.
I think the problem inherent to sleeve valve engines that technology can't overcome, or rather cannot yet overcome, would be the oil consumption and related emissions. On poppet valve engines, it has been surmounted by fitting rubber valve stem seals.
Do you see another problem ?
Cheers
Francois Dovat
For those who may ignore it, it must be said that the Knight was a double sleeve engine, which was much inferior to Burt-Mc Collum single sleeve engines.
Of course, a modern poppet valves engine is superior to a WW II era sleeve valve engine! It's hard to know which one would be the best if both concepts had concurrently been developed till nowadays. But we know that the last sleeve valve engines such as the Bristol Centaurus, RR Eagle and the late versions of the Bristol Hercules proved superior to similar poppet valve engines of their time.
I think the problem inherent to sleeve valve engines that technology can't overcome, or rather cannot yet overcome, would be the oil consumption and related emissions. On poppet valve engines, it has been surmounted by fitting rubber valve stem seals.
Do you see another problem ?
Cheers
Francois Dovat
#6
J. Edlund
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Posted 09 April 2004 - 10:16
Also in the same issue of Race Engine Technology Hans Hermann (consulting engineer to the race engine industry, expert in valve spring and valve train dynamics) continues:
"If you look at things from the standpoint of gas dynamics, usually you find that sleeve valves and so forth are only good when they are wide open and when they are half open they are terrible . Whereas the form of the poppet valve provides a really neat way of controlling the flow. And there is always backflow to control, which can be difficult for alternative systems."
"If you look at things from the standpoint of gas dynamics, usually you find that sleeve valves and so forth are only good when they are wide open and when they are half open they are terrible . Whereas the form of the poppet valve provides a really neat way of controlling the flow. And there is always backflow to control, which can be difficult for alternative systems."
#7
McGuire
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Posted 09 April 2004 - 11:10
Originally posted by J. Edlund
Also in the same issue of Race Engine Technology Hans Hermann (consulting engineer to the race engine industry, expert in valve spring and valve train dynamics) continues:
"If you look at things from the standpoint of gas dynamics, usually you find that sleeve valves and so forth are only good when they are wide open and when they are half open they are terrible . Whereas the form of the poppet valve provides a really neat way of controlling the flow. And there is always backflow to control, which can be difficult for alternative systems."
Exactly so. That was the advantage of the Knight scheme over the single sleeve for automotive use: Two concentric sleeves which could be deployed to travel in same or opposite direction at various points in the cycle, to obtain virtually any rate or timing. But of course two sleeves also double the reciprocating weight, friction, wear, cost, etc. and so on. Friction hp and oil consumption killed the Knight engine.
#8
ZoRG
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Posted 25 April 2004 - 09:15
I think the reason that other valve systems are not going anywhere, is simply that there isn't really that much wrong with poppet valves, maybe a case of if it aint broke, no fixing it.
After manufacturers spent so much time refining this system, and getting it to work reliably, why would they want to go the complete oposite way with a completely different system and venture into the unknown... you learn the hard way, and it would be a nightmare to have a bucketload of valvetrain failures. Even if there are no failures the wear rate on these so called rotary systems are very high.
The coates system is mentioned on that link you posted, I find it interresting everyone had good things to say about his system, obviously they did not study it. First of all the claims they made, 14000rpm with a SB V8 HAHA yea whatever, secondly that system has a poor design, from the way the ports are constructed, to the combustion chamber shape. thirdly, email them and ask them for a dyno sheet on "any" of theinr engines, another thing that is non existant. Then do a search on him and you will find he's been arrested for fraud, and a few engineers went to speak to him, they all claim he is a bit of a sneaky, character... This leaves alternative valvetrains with no modern development, which might be where one of the problems are....
Last year I spent around 6 months researching and modeling alternative valvetrains, in the end I still went for the poppet valve system, simply because its tried, tested, reliable, and with a VVT system really not that much wrong with it.
After manufacturers spent so much time refining this system, and getting it to work reliably, why would they want to go the complete oposite way with a completely different system and venture into the unknown... you learn the hard way, and it would be a nightmare to have a bucketload of valvetrain failures. Even if there are no failures the wear rate on these so called rotary systems are very high.
The coates system is mentioned on that link you posted, I find it interresting everyone had good things to say about his system, obviously they did not study it. First of all the claims they made, 14000rpm with a SB V8 HAHA yea whatever, secondly that system has a poor design, from the way the ports are constructed, to the combustion chamber shape. thirdly, email them and ask them for a dyno sheet on "any" of theinr engines, another thing that is non existant. Then do a search on him and you will find he's been arrested for fraud, and a few engineers went to speak to him, they all claim he is a bit of a sneaky, character... This leaves alternative valvetrains with no modern development, which might be where one of the problems are....
Last year I spent around 6 months researching and modeling alternative valvetrains, in the end I still went for the poppet valve system, simply because its tried, tested, reliable, and with a VVT system really not that much wrong with it.
#9
Bill Sherwood
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Posted 25 April 2004 - 10:21
The coates system is mentioned on that link you posted, I find it interresting everyone had good things to say about his system, obviously they did not study it. First of all the claims they made, 14000rpm with a SB V8 HAHA yea whatever, secondly that system has a poor design, from the way the ports are constructed, to the combustion chamber shape. thirdly, email them and ask them for a dyno sheet on "any" of theinr engines, another thing that is non existant. Then do a search on him and you will find he's been arrested for fraud, and a few engineers went to speak to him, they all claim he is a bit of a sneaky, character... This leaves alternative valvetrains with no modern development, which might be where one of the problems are....
I too am a little dubious about the claims they make.
They wouldn't return any emails I sent them either, mainly to do with how the power of the engine compared to a conventional poppet-valve engine at the sort of revs that a poppet-vavle engine runs at.
But!
The reason I'm not completely dismissing it is because of a guy in Australia in the 1960's by the name of Harold Clisby. He build a rotary-valve head for a Holden Red Motor (normally a 186cu in straight six, with push-rod operated two valves) that reputedly ran to in excess of 10,000rpm and blew away small block Chevy powered hydroplane boats.
It's all anecdotal though, I don't have any hard evidence sorry.
#10
ZoRG
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Posted 25 April 2004 - 19:24
Yup, I heard about that guy as well, I also saw a drag bike engine in australia that ran on rotary valves(Pictures of it), don't have the link anymore though.
I am not saying rotary valves can't work, however there are other problems to look at, mainly combustion chamber design, getting decent flow out of a rotary valve, sealing,efficiency etc etc. I used coates as a example of the only application that I know of doing any development even if it is in "fairy land"
I actually remember a post, I think on eng-tips where a guy came on and claimed his company manufactured the coates engines you see in the pictures, and that they were in no way functional.
The problem I have with them is that they have limited application with VVT technologies, they have limited optimization, I am sure they work well when run at constant rpm, but you can't play with thing as lift, or agressiveness or such, since it opens in a linear fasion as well as closes in a linear fasion. The limit to high rpm in today's engines as compared to the V8 engines you are talking about are not really the valvetrain anymore, its reliability. yes you might be able to free up a bit of power due to lower friction, however you will loose that power throughout the curve due to its other shortcomings.
I am not saying rotary valves can't work, however there are other problems to look at, mainly combustion chamber design, getting decent flow out of a rotary valve, sealing,efficiency etc etc. I used coates as a example of the only application that I know of doing any development even if it is in "fairy land"
I actually remember a post, I think on eng-tips where a guy came on and claimed his company manufactured the coates engines you see in the pictures, and that they were in no way functional.The problem I have with them is that they have limited application with VVT technologies, they have limited optimization, I am sure they work well when run at constant rpm, but you can't play with thing as lift, or agressiveness or such, since it opens in a linear fasion as well as closes in a linear fasion. The limit to high rpm in today's engines as compared to the V8 engines you are talking about are not really the valvetrain anymore, its reliability. yes you might be able to free up a bit of power due to lower friction, however you will loose that power throughout the curve due to its other shortcomings.
#11
malbear
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Posted 26 April 2004 - 01:02
Originally posted by ZoRG
I think the reason that other valve systems are not going anywhere, is simply that there isn't really that much wrong with poppet valves, maybe a case of if it aint broke, no fixing it.
Last year I spent around 6 months researching and modeling alternative valvetrains, in the end I still went for the poppet valve system, simply because its tried, tested, reliable, and with a VVT system really not that much wrong with it.
Zorg did you look at this one
THE BEARE HEAD
(1)The 6-stroke engine is fundamentally superior to the 4- stroke because the head is a net contributor to, and an integral part of the power generation within the engine.
(2)The 6stroke is thermodynamically more efficient because the change in volume of the power stroke is greater than the intake, compression, & exhaust strokes.
(3)The compression ratio can be increased because of the absence of hot spots.with a compact double squish, twin spark combustion chamber
(4)The rate of change in volume during the critical combustion period is less than in a 4stroke.
(5)The absence of valves within the combustion chamber allows design freedom. The valving is not subject to full cylinder temperatures or pressures.The upper piston is efectivly oil cooled.
(6) A one-piece engine from crankshaft to upper shaft becomes feasible. No head gasket.
(7)Fewer components, 15 per cylinder compared to 40 for a 4-stroke. Therefore the cost of manufacture is much less.
(8)Can be fitted to standard engine blocks so the market is much larger than the OEM sector , also includes the retrofit aftermarket sector.
The engine has proven to be robust on the race track, & have significant advantages over 4-strokes
(1)The valving is desmodromic
(2)There are no valves to drop or bounce.
(3)The rev limit is only what the bottom end can stand.
(4)Gas flow on intake increase of 20%.
(5)No possibility of engine damage if the timing belt slips or snaps
(6)The reed valves are so close to the intake ports that their tips become the virtual port opening. This achieves variable port area & variable engine demand valve timing. The tips open late & small amounts with low throttle settings & open early & fully at full throttle.
(7) anything that is currently being applied to two stroke porting can also be applied to this concept
malbeareBEARE HEAD
#12
ZoRG
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Posted 26 April 2004 - 08:02
Yes, I did, I see you posting on here some time ago and was actually hoping you would chime in.
I did have a look at your design, and your patents, I rescanned them quickely to refresh my memory to construct a head like that, for a 4 cylinder inline might be a little more tricky than for a motorcycle engine. It is impressive on the bike engines, have you got any data as to how feasable it would be in a high rpm forced induction engine, from the animations it seems that your upper piston might not be strong enough to handle this and getting the exhaust gasses out also becomes a little more difficutl? I would also like to know if you did any studying on wear rate, as your system seems fine for a bike once again, but the wear rate seems a little high for automotive use where engines see 300,000KM with one head?
I also found no dyno sheet on your website comparing you system vs a conventional system. This is unfotunately a big lacking part in most "new" idea's/inventions, there is no hard evidence to back it up, people want to see it black on white. Have you done a comparison?
I did have a look at your design, and your patents, I rescanned them quickely to refresh my memory
to construct a head like that, for a 4 cylinder inline might be a little more tricky than for a motorcycle engine. It is impressive on the bike engines, have you got any data as to how feasable it would be in a high rpm forced induction engine, from the animations it seems that your upper piston might not be strong enough to handle this and getting the exhaust gasses out also becomes a little more difficutl? I would also like to know if you did any studying on wear rate, as your system seems fine for a bike once again, but the wear rate seems a little high for automotive use where engines see 300,000KM with one head?I also found no dyno sheet on your website comparing you system vs a conventional system. This is unfotunately a big lacking part in most "new" idea's/inventions, there is no hard evidence to back it up, people want to see it black on white. Have you done a comparison?
