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Poppet Cylinder

Why not use the same idea for valves as a cylinder?
  [vote for,

How come we don't just use the same idea for a poppet valve for the cylinder, you wouldn't have the same issues of seating it as you would a valve, since the sealing is already done. It's more complicated and stupid, but why didn't anyone who posts dumb things say this one by now?
MarcStinebaugh, Mar 09 2007

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       I don't know.
zeno, Mar 09 2007

       Maybe it's just too stupid?
BJS, Mar 09 2007

       maybe they just did. Or maybe you just stole MY idea.
the dog's breakfast, Mar 09 2007

       Uhm Im not sure I follow your logic. Poppet valves open and close they have no linkage and so cannot really be used in a power application. They also do not seal throughout their range of motion and so only seal when in the closed position. Perhaps I am misunderstanding but I do not believe it would be possible for this to work.
jhomrighaus, Mar 09 2007

       A poppet valve is a nice, lightweight bit of metal, easy to fling back and forth. Using a piston to seal the opening requires:   

       -More mass in the form of an extended cylinder skirt that keeps the piston aligned at full extension   

       -Piston rings, if you want a good seal. But how do you compress them when the piston slides back in? Maybe just machine it out of solid graphite. Good luck with that, by the way.   

       -Lubrication of the piston. Tricky. Ooh, emissions bad, and lossy too. On the upside, the oil changes itself, you just add a quart every 500 miles.   

       This idea has a few merits:   

       -The extended cylinder skirt and opening need not be symmetrical, thus shooting the charge into the firing cylinder in whatever direction you choose.   

       -The cylinder valve can be driven with a crank instead of a cam - how far the piston has to travel to open the valve duplicates the function of the cam's extended low spot.   

       -Crank drive means no valve float even at F1 speeds. A thrown conrod maybe, but no float.   

       -More exciting backandforthy stuff to look at.
elhigh, Mar 13 2007


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