Idea for my next simple engine

[PaulR]

Having decided to put Frisbie to one side, I think I'd like to build something in a vertical orientation and came up with this bar stock abomination but it seems too simple - have I missed something?

It's another single acting rotary valve engine, with in and out holes on opposite sides of the valve shaft, with the exhaust going out via the end of the valve. The piston has a shaft through it in the manner of some steam pumps, which is connected on both sides (for balance) to a pair of flywheels which also turn the valve. To keep the weight down, I was thinking of making the piston a sealed tube with a thinner rod fastened at the top end running in a guide (or the piston could just be sealed at the bottom with a longer guide rod connected there or just make it out of aluminium although I don't possess any at present and don't much care for it!).

The sketch isn't to scale and omits all the little details - I've omitted the support column in the left-hand drawing.

[Jasonb]

Very similar valve arrangement to Elmers No19 except he has a couple of flats on the valve shaft. The flats allow the inlet/outlet to stay open longer without weakening the shaft with too large a size holes, they could be done with a file.

Guide arrangement should be fine.

If you find your bit of tube first then the rest can be sized to that. 15mm copper plumbing tube or are you thinking smaller and using the same 19mm square for the cylinder a syou did with the previous? Could simply drill an 8mm hole most of the way through a piece of 10mm bar and just leave 3-4mm at th eend to fix the piston rod to. Best to have the closed end nearest the valve as that reduced "dead volume"

[PaulR]

Very similar valve arrangement to Elmers No19 except he has a couple of flats on the valve shaft. The flats allow the inlet/outlet to stay open longer without weakening the shaft with too large a size holes, they could be done with a file.

Guide arrangement should be fine.

If you find your bit of tube first then the rest can be sized to that. 15mm copper plumbing tube or are you thinking smaller and using the same 19mm square for the cylinder a syou did with the previous? Could simply drill an 8mm hole most of the way through a piece of 10mm bar and just leave 3-4mm at th eend to fix the piston rod to. Best to have the closed end nearest the valve as that reduced "dead volume"

Thanks as always. I'll have a think about flats vs holes and have a look at that one of Elmer's. Yes, probably a 3/4" square cylinder again, for the piston I was thinking of drilling all the way through some bar and soldering or threading on one or both ends depending upon whether the guide rod is attached top or bottom but yes, bottom end enclosed in either case.

[astroud]

Another option is to use radial grooves similar to used on the 'River Queen' engine , see attached.
I have started a build inspired by the design.

[PaulR]

Another option is to use radial grooves similar to used on the 'River Queen' engine , see attached.
I have started a build inspired by the design.

Thanks for this, I built something similar a long time ago but I seem to recall it didn't run at all well. Still, it's another option to keep in mind, cheers!

[astroud]

I can believe it didn't run well. When I look at the plans the grooves only cover 180 deg of the valve circumference, no allowance made for the 90 deg between the inlet/outlet ports and the port for the cylinder feed. As for the conrod, 1/16 thick with a kink in it to provide clearance...  I have modified the design for my build.

[PaulR]

I can believe it didn't run well. When I look at the plans the grooves only cover 180 deg of the valve circumference, no allowance made for the 90 deg between the inlet/outlet ports and the port for the cylinder feed. As for the conrod, 1/16 thick with a kink in it to provide clearance...  I have modified the design for my build.

Are we going to see a build log? I'd be interested!

[astroud]

Thanks for your interest, I will posted a few pictures and a write up once (if) I have got a run out it, still a few weeks away.
Andrew