Oscillating I.C. Engine

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Brian Rupnow

Design Engineer
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A few years ago, Philip Duclos designed a rather homely (or so I thought) little engine with an oscillating cylinder, not unlike one of Elmer Verburg's steam powered "wobblers". The REALLY BIG difference was that this engine was gasoline powered.----and---It was a hit and miss engine---and it was air cooled. It was a very clever design, and according to Philip Duclos, it ran well. I want to build something different enough to be interesting, and to add my own personal touches to "pretty it up" a bit. I give Philip full credit here for his original design, and hope that wherever he may be now, that he smiles a bit when he sees what I am doing to his "Whatzit" engine.----Brian


 
Ok Brian you’ve got me. I’m hooked. Just have to see what you come up with on this one. If you can pull it off I’m not sure you’ll be able to put it on the shelf with the rest of your engines . . . . this one might have to be kept in a cage. :eek:
 
Bob--I did a web search for "oscillating internal combustion engines", and didn't find any. Then I searched specifically for "Whatzit engine" (that was the name of the one Philip Duclos designed and built) and couldn't find anything. I think this will be a lot of fun. I seem to vaguely remember a write-up where somebody had built one but they couldn't keep the spark-plug wire from jumping off when the engine was running, so they installed a stationary "spark-post" very close to the moving sparkplug, and the spark jumped the gap to fire the plug in the oscillating engine.
 
This I have to see. I've missed your builds Brian, and I just knew you'd be back with something really special - although I half imagined you'd already have it built. It'll be even better to watch the design and build develop.

I can already see that this might end up being my next Rupnow engine build.
 
Brian, When I first saw the whatzit engine I knew I would build one some day, haven't got to it yet, but it's on the list. I too thought it was an ugly duckling. I really like where you are going with it. Can't wait to see it come together.
 
I saw an oscillating cylinder marine IC engine several years ago at the Mystic Seaport Marine engine event. It was a very interesting engine and I thought about trying to model it. I have only seen one, it is a rare form.

It will be fun to see how this one comes out.
 
I'm glad to see another Brian Rupnow project underway.

Sparks jumping a gap? Now that's interesting.

I can't wait for the chips to start flying.

--ShopShoe
 
Very interesting and unusual project.
I wander how the sealing against compression is achieved since in steamer is usually dependent on the spring but suppose IC has much higher pressure.
 
So now, after another four hours of modelling, it becomes clearer how this can be. The green support stanchions are fixed in position to a base. On the non carburetor side, there is a steel ball bearing setting in the recess at the end of the stub-shaft on the side of the cylinder. Then there is a 1/4" set screw resting against the outer side of the steel ball, locked in position with a 1/4" hex nut. On the carburetor side, there is a 1/16" cross section rubber o-ring (I will probably use Viton because of the heat.) setting between the end of the boss on the cylinder side stub-shaft which is hollow, and a flat bottomed counterbore in the green stanchion. This provides an air tight seal. The carburetor is bolted to the outside of the stanchion, and doesn't move. I will probably stick a paper gasket between the carburetor and the stanchion, but for now I haven't shown it. In one of the pictures, you can see the intake valve on the same end as the sparkplug--it is an atmospheric intake valve and requires no valve lifter. The exhaust valve is on the other side of the carburetor block, and will be operated by a lifter. There is a single hole in the side of the cylinder, and as in the Webster engine, it serves as both intake and exhaust port. You can see the (purple) head of the exhaust valve in the cross section.


 
Hang on boys, I'm modelling as fast as I can!!! Wife and I had to drive to Hamilton this morning to welcome my newest grandchild, Benjamin--8 pounds 7 ounces born at 6:30 this morning.--Mom and baby are doing well---Ben looks just like me--No hair and no teeth!!! This engine is a four cycle. The carburetor is attached solidly to the dark green cylinder support stanchion, which does not move. Strange as it may seem, the valves are both mounted in the same block that holds the carburetor, so the valves don't move either. There is a cam lobe on the far side of the red gear, setting in a cut out area in the pale green crankshaft support and the "pinkish/purplish" rectangular part with the round dark blue pin in it is the exhaust valve pushrod. That round dark blue pin is the "exhaust valve lockout latch" that the "hit and miss lever" catches on to send the engine into "miss" mode.---More to come!!!---Brian
 
I am really liking this!

Looking forward to seeing this through.
 
Hang on boys, I'm modelling as fast as I can!!! Wife and I had to drive to Hamilton this morning to welcome my newest grandchild, Benjamin--8 pounds 7 ounces born at 6:30 this morning.--Mom and baby are doing well---Ben looks just like me--No hair and no teeth!!!

Hopefully another engine maker. We currently have 1 three year old grandson, with another 2 grandchildren on the way, one in August and one in September.

Paul.
 
The modelling is completed for this engine, except for riser blocks under the baseplate so the flywheel doesn't hit the bench-top. NOW---This is the point at which I may do something really crazy!!! Remember how, in another thread I asked about an offset, gear driven flywheel. You will see that even if this flywheel did have "deflector blades" soldered into the lightening holes in the flywheel web, to create a fan effect, the air wouldn't blow on the cylinder where I want it to. Now--If I extended that crankshaft support block closest to the flywheel about 2 1/2" horizontally, moved the flywheel over the same amount and mounted it on a stub shaft attached to the crankshaft support block, and popped a couple of 2.5" o.d. spur gears in there, the flywheel would be right where I need it to be. One gear mounted on the end of the crankshaft and one mounted on the flywheel--the fan effect from the flywheel would blow directly over the cylinder fins. If it didn't work, I can replace the extended crankshaft support with one similar to what is shown in the model, move the flywheel back, and remove the gears. All I would be "out of pocket" for would be a couple of purchased hardened gears. (I could even make the gears myself for that matter.)---Whatcha think???
 
Good idea Brian, just don't forget that with the gears, the flywheel and fan blades will be rotating in the opposite direction.

Paul.
 
How about a pair of miter gears allowing you to drive a fan back across the fins of the engine block? I don't know....I just like watching the design develop in CAD and all the possibilities. Do what you think is best Brian! It is looking good!
 
Something unusual here---In his book 'The Shop wisdom of Philip Duclos' where these plans originated, Philip specifies the use of "Hot rolled or cold rolled steel" for the cylinder. He specifies cast iron for the rings. Okay--I can see the need for the strength of steel as opposed to cast iron because of the two pivot bosses on the outer walls of the cylinder, but I have never seen steel specified for a cylinder before. I don't think that it is a mistake. I'm just very curious as to whether steel will work satisfactorily for the application.--Any opinions??----Brian
 
I really wish I could make the cylinder from aluminum, it would be so much easier to machine. Almost every plan I have ever seen calls for the cylinder to be cast iron, and any that have an aluminum cylinder always call for a cast iron liner. I know, my weedeater, chainsaw and lawn mower all have gas engines with aluminum cylinders, and they seem to get away with it just fine. The aluminum I use is just common bar stock purchased from my local metal supplier, and I have never asked what grade it is. Probably 6061, but I'm not sure. I don't know if all the other hundred million small engines with aluminum cylinders are running some special aluminum material that I don't have access to. I hope I get some more insight into this before I actually begin the build process.---Brian
 
At least in small scale I believe steel works quite well. Bob Shores Peewee V4 that I'm currently building specs 12L14 for the cylinders, aluminium piston and cast iron rings. I think Steve Huck's V8 also uses this combination and I know he has many running hours on his engines.

As far as the Ali, I think you'd get away with it, but the pivots would probably have to be made of a different material, especially the (I assume) hollow one that the port/s run through. Using an O-ring instead of cast iron rings should protect the bore but if it did wear quickly you could either bore it out and reduce the pressure on the O-ring or insert a cast iron sleeve.
 
In my copy of his book the cylinder spec. is CRS, HRS or cast iron. It's not in the text, it is on page 128 above photo 8. As for your question, I think the only problem with an aluminum cylinder on this engine are the pivot points. I don't think the aluminum would hold up.
 

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