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 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 random, halfbakery