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The four-stroke engine with rotary cylinder block

by zhanghao2005
Tags: block, cylinder, engine, fourstroke, rotary
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Clausius2
#19
Aug14-05, 11:20 AM
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I have realised some problems about this design (sorry man, but if you have posted your invent here, our main mission is to bring you down to the floor ):

i) the performance in exhaust and intake flow is very studied in traditional engines. I don't see how the combustion chamber can swallow air during the rotation. What kind of valves shape would you use?. When the combustion chamber is nearly to end the open angle for intake, the effective shape of the intake duct will be very strange, with a great loss of pressure due to it. I am not able to explain it better, but imagine just the moment when the intake valve is opened and the cylinder block wall approaches it. Also, it would be a complex flow induced by the rotation of the chamber. The nature of this initial flow have a GREAT impact on the combustion process. So a further study will be needed.

ii) combustion process: despites the flow induced by the intake, the combustion process is going to be necessarily influentiated by rotation. Firstly it will be a great cummulation of gasoline near the spark plug, because it is a weighter component. This could be a good thing indeed. It is a great mechanism of producing an stratified mixture and avoiding the effects of flame failure near walls. But what affraid me most is the fact of the spark plug being attached to the outer casing. The plug needs a portion of mixture which initiates the premixed flame. In Otto-Diesel engines, the flame can advance with certain grade of spherical symmetry, but in this engine both burnt gases and flame will be influentiated by the rotation, and by means of the rotation inertia both flame and burnt gas will be prone to remain in the most rearward wall facing the spinning, enhancing the wasting of a great amount of fuel.
Cyrus
#20
Aug14-05, 11:28 AM
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Dont forget, Sir Frank Whittle had to practically BEG the british military to get funding to work on the jet engine during WWII, and even he was shot down a few times.

"While often regarded as the father of modern jet propulsion systems, the young Frank Whittle tried without success to obtain official support for study and development of his ideas. He had to persist his research on his own initiative and received his first patent on turbojet propulsion in January 1930."

Sadly, I agree with kennethman man. Even if his engine did work, I dont see it making much change, at least in the auto industry, unless it can provide benifits that are SIGNIFICANT in efficency. You gota remember, people are buying hummers that get 8mi/gal HIGHWAY, frankly, people in the auto industry really just DONT CARE. But I do think it could make it way to powering other devices, such as machines for factories etc. But then again, what company would want to pay retrain their technicians on how to service this new engine if it does not provide, ball park 20-30% efficiency. Its just cheaper to keep what does work and is the industry standard for so many years.

They hadn't rejected wankel model by the way, they tried it and they have realised about its defects.
The ONLY car to use a wankel is the nissan. Some aircraft use them, due to the low vibration. But still, go check out any small airplane, its engine is a STANDARD opposed 4 or 6 cylinder. These engines have more vibration than a wankel, but any pilot will tell you that they simply cant afford to replace the seals on the end of the wankel that go bad much faster than the seals on a piston. For a wankel, you have to practically rebuild the engine every time those seals go bad. My little honda has 100k+ miles on it with the same seals. Its a matter of how much money one is willing to spend for the small benifits of a particular engine. Most likely, his engine would have to be used on something highly specialized, not generalized.

Oh, and as far as his picture goes, the only thing I see that could use changing is his pistons. Dont make them square, give them a radius of that circle, so on the compresson stroke, you dont have that wasted space. You can get a very high compresson, and possibly avoid the spark plug.
brewnog
#21
Aug14-05, 11:37 AM
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Quote Quote by cyrusabdollahi
The ONLY car to use a wankel is the nissan.
Mazda's RX-8 uses a Wankel.

I share your sentiment about Whittle though, I think we all have something to learn from his story.


Quote Quote by cyrusabdollahi
Oh, and as far as his picture goes, the only thing I see that could use changing is his pistons. Dont make them square, give them a radius of that circle, so on the compresson stroke, you dont have that wasted space. You can get a very high compresson, and possibly avoid the spark plug.
I didn't pick up that the pistons would be square! Why would they be square? How would square holes be sealed, or even bored and honed for that matter?
Have I missed something? Usually!

I anticipate that one of the problems encountered with this design would be effective sealing of the combustion chamber. Cylinder pressures under combustion are immense, and I'm having difficulty seeing a way to seal what would effectively be the cylinder head, since it's supposed to be able to move relative to the block. Kenneth, any more info on the related engines which have actually been made?

What do you mean about avoiding the spark plug? Compression ignition? Using a Diesel cycle rather than an Otto? I would imagine that that would have many problems of its own!
Clausius2
#22
Aug14-05, 11:40 AM
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Quote Quote by cyrusabdollahi
Dont forget, Sir Frank Whittle had to practically BEG the british military to get funding to work on the jet engine during WWII, and even he was shot down a few times.

"While often regarded as the father of modern jet propulsion systems, the young Frank Whittle tried without success to obtain official support for study and development of his ideas. He had to persist his research on his own initiative and received his first patent on turbojet propulsion in January 1930."

Sadly, I agree with kennethman man. Even if his engine did work, I dont see it making much change, at least in the auto industry, unless it can provide benifits that are SIGNIFICANT in efficency. You gota remember, people are buying hummers that get 8mi/gal HIGHWAY, frankly, people in the auto industry really just DONT CARE. But I do think it could make it way to powering other devices, such as machines for factories etc. But then again, what company would want to pay retrain their technicians on how to service this new engine if it does not provide, ball park 20-30% efficiency. Its just cheaper to keep what does work and is the industry standard for so many years.



The ONLY car to use a wankel is the nissan. Some aircraft use them, due to the low vibration. But still, go check out any small airplane, its engine is a STANDARD opposed 4 or 6 cylinder. These engines have more vibration than a wankel, but any pilot will tell you that they simply cant afford to replace the seals on the end of the wankel that go bad much faster than the seals on a piston. For a wankel, you have to practically rebuild the engine every time those seals go bad. My little honda has 100k+ miles on it with the same seals. Its a matter of how much money one is willing to spend for the small benifits of a particular engine. Most likely, his engine would have to be used on something highly specialized, not generalized.

Oh, and as far as his picture goes, the only thing I see that could use changing is his pistons. Dont make them square, give them a radius of that circle, so on the compresson stroke, you dont have that wasted space. You can get a very high compresson, and possibly avoid the spark plug.
Boy, do you know how to read????. I have little to say about all this stuff that has nothing to do with the design of the OP. Don't quote me again, if it is not relationed with the main purpose of this thread.
Cyrus
#23
Aug14-05, 11:43 AM
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Sorry If i miss quoted you clausius. Do you think it would help to make those pistons have a curvature of the housing though? It should give you more compression.

I didn't pick up that the pistons would be square! Why would they be square? How would square holes be sealed, or even bored and honed for that matter?
Have I missed something? Usually!
If you look at the top of his piston, its flat. What Im saying is, why doesnt it have the radius of curvature as the cylinder wall. You can see the space inside there when its moved to top dead center because the cylinder wall is a curved circle and the piston head is flat. The pistons are round, but the head of the piston is pictured as being flat.
Kenneth Mann
#24
Aug14-05, 11:50 AM
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Quote Quote by Clausius2
When a thread comes in this way, I have nothing to do in it. It would take a face-to face conversation with you to make you realise I have never diminished or belittle those engines before hand.
Then, I believe we are pretty much in agreement. Thanks for the clarification.

Quote Quote by Clausius2
Diesel and Otto engines have been broaded studied. Maybe in the future, when the studies will be extended to those secondary models, they will get the foreground of the industry, but today they don't work as properly as Otto and Diesel engine. It's a trivial statement.
I'm not quite as optimistic as you about the good motives or lack of politics within the industry, but on this we can agree to disagree. The problem I see with waiting for a new idea to prove itself before it is accepted is the old chicken-egg problem. It won't be accepted until it has been proved, it can't be proved until it is thoroughly developed and tested, and it won't be developed and tested until it has been accepted by someone who can afford the cost of it. Thus many great ideas languish and die, unless they happen to be invented by someone with deep pockets, like Edison in his later years. You apparently have more faith in the natural goodness of humans than I do.

Quote Quote by Clausius2
Let's recover the main topic of the thread, please.
I concur. Maybe we can discuss some of the apparent problems, and possibly how they might be solved.

Quote Quote by Clausius2
I have not read all his post, nor I understood it well. Can anyone tell me where is the spark plug? Is it rotating or is it steady on the outer cage?. Thanks.
I think it is shown at the bottom of the casing. This would seem to be the logical place for it. It should not rotate, though with the (I think strange) double-rotation of the block and the crankshaft, I can't be sure. The drawings are very difficult to make out, we could do better with something clearer and easier to read. Maybe we should suggest that the author dedicate a site and put the information there.

KM
Clausius2
#25
Aug14-05, 11:50 AM
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Quote Quote by cyrusabdollahi
Sorry If i miss quoted you clausius. Do you think it would help to make those pistons have a curvature of the housing though? It should give you more compression.
Sorry, I am with very bad mood last days. My undergrad project doesn't work well.

Yes, I do think making such curved design would be better, but take into account that burnt and unburnt mixture could be accumulated in the edges of the pistion surface, because it would be a cooler and safer place to remain. Also a convex wall will influentiate combustion process in an unknown way. Combustion chambers have standard shapes which has been broadely experimentally tested. I am not able to predict the final performance when a change happens inside it.
Kenneth Mann
#26
Aug14-05, 09:24 PM
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Quote Quote by Clausius2
I don't see how the combustion chamber can swallow air during the rotation. What kind of valves shape would you use?. When the combustion chamber is nearly to end the open angle for intake, the effective shape of the intake duct will be very strange, with a great loss of pressure due to it.
I think this problem is solvable, but it will probably take work. Others have made somewhat similar designs and they have worked pretty well. The idea of a rotating radial engine isn't unique to this concept - - - what I see as different is their crankshaft arrangement, and I see problems with that, at least with the three-piston configuration. Look at how small the crankshaft is in comparison. I am afraid the power generated could twist that shaft like a pretzel. They can increase the block diameter, but that will add a lot of weight and waste a lot of space, unless maybe they can come up with more cylinders. I just don't know what the answer might be.

Quote Quote by Clausius2
Also, it would be a complex flow induced by the rotation of the chamber. The nature of this initial flow have a GREAT impact on the combustion process. So a further study will be needed.
True, but I think it can be done simply because it has been done before, on similar designs.

Quote Quote by cyrusabdollahi
but any pilot will tell you that they simply cant afford to replace the seals on the end of the wankel that go bad much faster than the seals on a piston.
And I think sealing this one will be one of the main problems they face in implementing an Otto Cycle engine, as is stated in the following:

Quote Quote by brewnog
I anticipate that one of the problems encountered with this design would be effective sealing of the combustion chamber. Cylinder pressures under combustion are immense, and I'm having difficulty seeing a way to seal what would effectively be the cylinder head, since it's supposed to be able to move relative to the block. Kenneth, any more info on the related engines which have actually been made?
Right! Basically they have a cylinder (the block) rotating inside another cylinder (the outer wall), and there has to be clearance for this. Compression will leak out all around the 'tops' of the cylinder chambers. This is essentially the problem that the Wankel has had to handle for all these years. I have run across a couple of rotating chamber Axial-Rotary piston engines in the past. Unfortunately, the one most like the one in this string seems to be long lost. I have an old article on the other, but it differs in that the pistons operate in the opposite direction (Power stroke is out from the center).Mostly non piston engines with similar sealing considerations are:
1. The Wankel
2. The Veselovsky Rotary Otto Cycle Engine - - basically like a Wankel turned inside out. The semi-triangular part is the cavity in the casing, where the rotor inside is semi-elliptical - - just the opposite of the Wankel.
3. The Bricklin Axial (pistons move parallel to the axis) Rotary Otto Cycle piston engine
4. The Starrotor Brayton Cycle engine - - Basically solves the problem by ignoring it and accepting lower compression ratio (~ 6 to 1), Which they can do because it is a Brayton Cycle engine (which depends heavily on a large volume of air rather than high compression.


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