Oddball engines and prototypes

[WilDun]

He's using a Tee Square, just how old is this ?

Anyways, it must be bullshit, he doesn't have glasses....

Did you mean "pigshit" Ken? - don't think he needed glasses for the photo anyway, And the square? - that's to go with the drawing board! All very interesting though and I'm sure Neil will be very interested too!
Done mostly in the nineties and that article may have been written around 2010 (I think).

[Flettner]

yes very intetesting but I see they dont use an open ended sleeve like Riccardo, Ha Ha and me.

[husaberg]

yes very intetesting but I see they dont use an open ended sleeve like Riccardo, Ha Ha and me.

Did you see what he mussed about the motion of the sleeve, that the bit i was curious about.

link to the other one i posted
https://www.kiwibiker.co.nz/forums/s...post1131056224

It came from Rob Collet who made comparativley more HP/litre and came much later, if you take away the effect of the blower as well.
Attachment 331871Attachment 331868Attachment 331870Attachment 331869
this is the sleeve drive he has although his is adjustable



when he says the issues with the piston shrouding the port this is what he means
buggar can't find the pic

[WilDun]

Did you see what he mussed about the motion of the sleeve, that the bit i was curious about.

link to the other one i posted
https://www.kiwibiker.co.nz/forums/s...post1131056224

Yes the article in your post, says he just made the sleeve reciprocating instead of oscillating (as in the Bristol engine). He says that with modern oils there was no need for oscillating motion anymore (originally needed to spread the oil over the surface of the sleeve).
Main problem is, if that arrangement is used in a two stroke, the sleeve is a mighty heavy piece of metal to be bobbing up and down (thinwall or not) at crankshaft revs!
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Here is an interesting piece of (two stroke) engineering from Poland (with a "Neil " type? sleeve/piston arrangement)



The crank arrangement seems to have been inspired by this Esso experimental design (no conrods) :-



Sorta mesmerising!

[lohring]

The top of an open ended sleeve is exposed to the full combustion pressure. It acts just like an extra piston with a small area and shorter stroke than the main piston. This probably at least makes up for any extra drag.

Lohring Miller

[WilDun]

The top of an open ended sleeve is exposed to the full combustion pressure. It acts just like an extra piston with a small area and shorter stroke than the main piston. This probably at least makes up for any extra drag.

Lohring Miller

Are you referring to the Polish engine?
The sleeve in this design would probably be considered the piston (if only because it reciprocates and acts on the crank), but also the inner part with piston rings and what looks like an "Orbital" type injector, should probably be considered a static piston.
So because of this static piston, the sleeve/piston isn't actually open ended any more and therefore is separated from combustion pressure - the top end area you mention (with an extended diameter) can then become a piston for a compressor/blower or a supercharger (depending on the diameter used.)

I'm quite keen on that piston/crank arrangement too - but the design and layout of this engine does look slightly awkward in a motorcycle!

I could of course be wrong but that's how I see it!

[lohring]

It doesn't look like that would be true for any sleeve valve that uses rings for the top seal. However, the piston's rings will tend to drag the sleeve along with the piston. I think the friction loss of sleeve valves is actually smaller than poppet valve trains, but I'm not aware of actual tests.

Lohring Miller

[WilDun]

It doesn't look like that would be true for any sleeve valve that uses rings for the top seal. However, the piston's rings will tend to drag the sleeve along with the piston. I think the friction loss of sleeve valves is actually smaller than poppet valve trains, but I'm not aware of actual tests.

Lohring Miller

When it comes to using the sleeve with extended top diameter as a (relatively speaking) low pressure compressor - I feel that it may not need to have totally positive displacement in this case and so it might not have to run snugly (or even touch) the inside walls of the cylinder! (ie the upper extended diameter part of the cylinder) or am I missing the point? - but what do you think?

This is just a schematic for the cycle in one cylinder of the engine from Poland we are discussing. :-

[lohring]

Once again, I think simpler is better. The sleeve is hard enough to make good enough to seal only the cylinder well. The Bristol spent a lot of time getting their four stroke sleeves good enough. No one else has done it recently in a production engine as far as I know. An even simpler uniflow engine is the double piston design. It has had several successful production versions. The only complication is the double crankshaft. Otherwise, it doesn't suffer from many of the other uniflow engine faults. I just don't see anyone putting the required serious development money into any new IC engine.

Lohring Miller

[WilDun]

Once again, I think simpler is better. The sleeve is hard enough to make good enough to seal only the cylinder well. The Bristol spent a lot of time getting their four stroke sleeves good enough. No one else has done it recently in a production engine as far as I know. An even simpler uniflow engine is the double piston design. It has had several successful production versions. The only complication is the double crankshaft. Otherwise, it doesn't suffer from many of the other uniflow engine faults. I just don't see anyone putting the required serious development money into any new IC engine.

Lohring Miller

No you're right, the days of any real breakthrough inventions in this field are over I guess and if I were a manufacturer I wouldn't try to change!

Yes the opposed piston, uniflow scavenged engine offers a lot and is my favourite.
I do also believe that this design offers a lot too, especially with its crank operation - the cylinder also resembles the RR Crecy (in some ways) and as such, would lend itself to uniflow operation, instead of the traditional Schneurle scavenging!

Schneurle was fine for the last 80 years or so, but was also the root of all evil! - why did we do it?

[lohring]

You get a lot better piston and combustion chamber shape with the Schnuerle system than outboard style cross flow designs. The only alternative cross flow design with promise was the QUB cross flow design. The uniflow designs also have reasonable combustion chamber shapes. Below are some sketches that give you an idea of the issues. I think the development work by Gordon Blair sponsored by Yahama did a lot to refine the current 5 transfer engines.

Lohring Miller

[WilDun]

Gordon Blair did a lot of research for Yamaha etc. and as well as his two stroke work he also did a lot of research on four stroke cylinder head design - eg the Toyota 4 valve heads (which were I believe made by Yamaha).

Dr Blair was a big fan of the two stroke and dedicated to improving the existing Schneurle system but significantly, he didn't forget the four stroke (his main bread and butter!).
(BTW he lived and worked only a few miles from where I grew up).

When I said that the Schneurle system has done its dash, I meant that, although commercially viable and reasonably successful for quite a while, the whole design needs to be replaced by something which almost eliminates a fresh, oil laden charge from coming into contact with the outgoing charge either in the cylinder or in the exhaust pipe - that really was the cause of its demise on the road going machinery.
The two main things which can save it are its power to weight ratio, a clean exhaust and the possibility of simplicity, that is the only chance it will ever have in making it back on the roads. - The opposed piston is a distinct possibility here - as for combustion chamber shape, could HCCI take care of that concern? and at the same time get rid of all our 'squish' woes (doesn't really matter about the shape anymore)?

Here I go again! Gordon Blair would turn in his grave if he heard me! - so I'll shut up and if someone steps up and proves me wrong, then, so be it!

[lohring]

I think the big Etec engines are as close as modern two strokes come to your ideal. The combination of a simple basic design with fuel and oil injection and a variable length pipe all controlled by modern electronics works well. Carefully controlled oil injection seems to be able to reduce oil consumption to 4 stroke levels. I don't know if similar engines could be developed for road use. The operating conditions are very different. Orbital tried, but their success has been limited as far as I know.

Lohring Miller

[WilDun]

I think the big Etec engines are as close as modern two strokes come to your ideal. The combination of a simple basic design with fuel and oil injection and a variable length pipe all controlled by modern electronics works well. Carefully controlled oil injection seems to be able to reduce oil consumption to 4 stroke levels. I don't know if similar engines could be developed for road use. The operating conditions are very different. Orbital tried, but their success has been limited as far as I know.

Lohring Miller

Too risky for any manufacturer to make big changes in these uncertain times when the fickle customers are more concerned with fashion and fantasy than engineering excellence and innovation!.......... But let's keep plugging on - this stuff to me is much more exciting than any thriller on TV! ........ How the hell could crime be more fascinating than this!

[Frits Overmars]

... this stuff to me is much more exciting than any thriller on TV! ........ How the hell could crime be more fascinating than this!

What's next Will? Trying to steal a bike? I hereby deny that I ever said: "You must ride a two-stroke as if you just stole it".