Oddball engines and prototypes

[Pursang]

Combined piston/rod like that are used in small oil-less air compressors, often used for airbrush. the bigend runs a ballbearing packed with grease and the piston ring is teflon running on a hard anodized sleeve. They are quiet, light, and have zero chance of contaminating the air with oil, but they do not last a long time.

I've been trying to find an image I had, of a Super Simple one.

The conrod is curved and one side of the elliptical piston lip seal protrudes from the cylinder at the bottom of the stroke.
One outlet check valve in the cylinder head, and that's it!

Cheers, Daryl.

[OopsClunkThud]

two oilless compressor examples:

the ring keeps the piston/rod from ever touching the cylinder, until it does and then it all goes bad. But not a hard fix.

[ceci]

It is possible to omit the hinge, but it requires a peculiar type of piston, pictured below, a project from the late Henk van Veen, of Van Veen Kreidler fame, in which I was also a little involved. It's just a pity that it cannot work in conjunction with cylinder exhaust ports.
Attachment 343779

With mechanisms like these the problem could be solved

[ken seeber]

The combined piston/rod design with its inherent tilting piston face:

Because of the tilting, there might be limit on the achievable compression ratio because of the head/piston clearances required. Just to go against all Frit's fundamental KISS principles, one could have an opposed piston version with contra rotating cranks. This could result in the two pistons tilting in the same direction, thus maintaining a parallel gap between them. Valving would have to be circumferential around the bore.

Just can't see any good reason to make one though.

[husaberg]

The combined piston/rod design with its inherent tilting piston face:

Because of the tilting, there might be limit on the achievable compression ratio because of the head/piston clearances required. Just to go against all Frit's fundamental KISS principles, one could have an opposed piston version with contra rotating cranks. This could result in the two pistons tilting in the same direction, thus maintaining a parallel gap between them. Valving would have to be circumferential around the bore.

Just can't see any good reason to make one though.

[Frits Overmars]

With mechanisms like these the problem could be solved

Ceci, in your third image, inventor Bryan Parsons seems to ignore the fact that during most of a revolution there is an undesirable connection between crankcase and exhaust. I have not been able to find the full patent document; can you post it?

[WilDun]

Yes Frits,
I did look at this piston type before and I believe I posted a picture of it a long time ago in this thread.

I came to the conclusion then that it wouldn't work in an engine because of the angularity of the actual piston part at 50% stroke - no amount of curvature on the sealing area of the piston would help!
After all, the actual sealing area of the piston would have to be elliptical (or something close) at that angularity wouldn't it?

Hossack's engine did actually work after a fashion with it's sculpted (curved) thrust faces but the piston section was actually rectangular!
Also as I said earlier, what about the narrow gaps between the piston crown and the cylinder (ie with a curved sealing area ) when at TDC?

But of course I may have missed something and if so, I'm sure I can rely on you guys to point it out!

[ceci]

Ceci, in your third image, inventor Bryan Parsons seems to ignore the fact that during most of a revolution there is an undesirable connection between crankcase and exhaust. I have not been able to trace to find the full patent document; can you post it?

I remembered that Boyesen had a patent for a barrel exhaust closing mechanism and looking for it I found that, but only that is the only thing I found
https://books.google.es/books?id=-fT...atents&f=false

[Frits Overmars]

Thanks Ceci. Yes, Boyesen patented both rotary and oscillating ways of controlling two-stroke exhaust timing, but I was wondering if Bryan Parsons had made a provision for a similar device in his above-shown patent.

[lohring]

The problem with tilting pistons is the seal area goes from circular to elliptical. If the tilt is small the change will be small, but will still be hard to seal. It does work in pumps, though.

Lohring Miller

[Michael Moore]

Frits, here's the Parsons 2T patent document:

https://patentimages.storage.googlea.../US4924824.pdf

[ceci]

Like most, I think those piston / connecting rod are good for air compressors.
How to use them in 2S, to lighten engines like the 99Z. This piston / connecting rod is the same bore
I am convinced that by changing some things, this approach would be very effectivehttp://www.motobec.fr/etude-technique.html
https://patents.google.com/patent/US4276858A/en

[Pursang]

https://books.google.es/books?id=-fT...atents&f=false

I notice on the same page, a patent issued to the mostly unsung 2 stroke inventor, Mr. Kenneth P. Seeber.

What the world needs is cat converters blocking exhaust ports.

Cheers, Daryl.

[WilDun]

Kenneth! KENNETH!. KENNETH! where are you? - have you been doing stuff behind our backs?? ....... ..... NO?

[Pursang]

Kenneth! KENNETH!. KENNETH!

Cheers, Daryl.