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  • Oscillating I.C. Engine

    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


    Brian Rupnow

  • #2
    Brian,

    This looks like a fun project. The cylinder appears to oscillate about its center of mass, minimizing vibration. With no connecting rod the piston can have a long stroke, with minimal side-loading.

    I look forward to getting more details as you proceed.
    Allan Ostling

    Phoenix, Arizona

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    • #3
      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.
      Brian Rupnow

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      • #4
        Originally posted by brian Rupnow View Post
        ... 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.
        It's hard to overstate the entertainment value of such an engine, if it runs.

        The oscillating cylinder with its cooling fins could be quite effective. I spent much of my career calculating convection heat transfer coefficients -- I feel safe in saying that there are no published formulas which pertain to this.
        Allan Ostling

        Phoenix, Arizona

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        • #5
          They are usually called "Free Piston Linear" motors/generators (either single or dual piston). Youtube has lots of videos of them.

          Although yours has a tied end and is not strictly free .. its the same principle.

          Rob

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          • #6
            Found this example of a 3/D printed one.

            going to be one rattling SOB with the weighted crank throws on the wrong side though

            https://s.yimg.com/fz/api/res/1.2/5B...e/IMG_3812.JPG

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            • #7
              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.


              Brian Rupnow

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              • #8
                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
                Brian Rupnow

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                • #9
                  Originally posted by brian Rupnow View Post
                  ... the valves are both mounted in the same block that holds the carburetor, so the valves don't move either.
                  This necessitates an O-ring seal, which your drawing shows. The seal has to withstand the combustion pressure and temperature in the cylinder, with the inboard face undergoing oscillating rotary motion. Do you expect any problems with this?
                  Last edited by aostling; 05-20-2015, 11:48 PM.
                  Allan Ostling

                  Phoenix, Arizona

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                  • #10
                    I'm not expecting a problem, and I will probably use a high temperature Viton o-ring. However, I am an optimist, and i never really expect insurmountable problems. if I thought it was going to be a really big problem, then I probably wouldn't attempt to build this engine.
                    Brian Rupnow

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                    • #11
                      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???
                      Brian Rupnow

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                      • #12
                        Good Morning Brian, at least it is morning out here.
                        Not trying to be picky but you would be blowing the air across the the cooling fins not along them like most air cooled engines do.
                        Don't know what the difference in cooling would be but I am sure it would make a difference.
                        Is there some way you could drive a fan to cool along the fins?
                        Larry - west coast of Canada

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                        • #13
                          I THINK those gears will have to be pretty good to stand the hammering they will get as the load reverses every revolution. Might be noisy as well.

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                          • #14
                            Cuttings--Since this will be a hit and miss engine, and will be drawing ambient room temperature air in and out of the cylinder during all of the "miss" cycles, it won't get very hot anyways. I just want the air around the fins to move a bit. It's a kind of "Any air movement is better than no air movement at all" kind of thing. Cameron--I hear you about the noise. I might dip into the Rupnow retirement fund and buy a set of gears with hardened teeth.---Haven't decided yet.---Brian
                            Brian Rupnow

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                            • #15
                              Originally posted by brian Rupnow View Post
                              ... I just want the air around the fins to move a bit. It's a kind of "Any air movement is better than no air movement at all" kind of thing. ...
                              The fins are moving, so air movement is guaranteed without a fan. Are you thinking that will not be enough?
                              Allan Ostling

                              Phoenix, Arizona

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