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Ok, there are two valve heads, three valve heads (Honda), four valve heads, five valve heads (Yamaha) but why is isn't there a one valve head, with a switchable duct to draw in fuel and air, or direct exhaust away?
Before cynics say "valve bounce" maybe desmodronic control would work even for such a
big valve as this. Maybe.
(??) Valve overlap
http://www.lightnin...m/valve_overlap.htm
" Valve overlap is designed by cam manufactures to promote cylinder filling on the intake cycle by using the vacuum created in the exhaust system" [half, Oct 04 2004]
A bit more about valve overlap
http://web.tampabay...3liter/exhaust.html
"If there was no valve overlap, it would be 100% impossible to completely irradicate all of the spent gases from the cylinder" [half, Oct 04 2004]
Gnome Monosoupape
http://www.enginehi...e%20Monosoupape.pdf
[Fussass, Oct 04 2004]
(?) For the true single valve aficionado
http://www.swagelok...2Ejpg%26CTSCKey%3D4
This baby could serve all your cyclinders at once. You just have to rotate the handle real fast. [kbecker, Oct 04 2004]
[link]
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if I get what your saying, this would be complicated to achieve |
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What would be the benefit of this? Surely a switchable-duct-valve would cost as much as two normal valves..? |
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The link shows how they did it during WW1 with no extra parts, just one valve and some holes in the cylinder sleave. |
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Aha! Another invention for a fishbone magnet. |
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You may have only one hole in the cylinder head, but somewhere the path for exhaust has to separate from the path for incoming air/fuel. At that point you have at least a switch-over valve (link), which is already more than a single valve. Can we agree on a 1-1/2 valve cylinder? |
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I never understood why they have those plunger valves on cars. Must be real hard on the material to be slapped around like that. Something smooth and rotating (as in link) should also be possible. |
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There was a man a few years back who invented what could be the perfect system. It was a valve-less engine. He used a rotating drum with passages cut into it, one passage for the intake, one for exhaust. As the drum rotated, it exposed each passage in time with the cycle of the piston. Brilliant idea, not sure what ever happened to it. |
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why on earth would you want a one valve engine. the reason cars have more and more valves is to opptimize the amount of area for air flow.two valve heads are the worst. three are getting better intake breaths. and four and five are used in high perfomance engines. |
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excellent point, mini1. That was the rationale behind the invention of the rotating cylinder I mentioned above. It opened the ports completely, no valve in the path to interfere with flow. Of course, we could all buy the new Mazda RX-8 and get the rotary engine which also has no valves. |
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now I see what your talking about. |
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if I see what your talking about |
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All the talk about how silly a single valve system would be and nobody has considered that we inhale and exhale through the same port. Kind of scary when you think about it. If you don't pause between exhaling and inhaling, you might inhale the same spent gasses you just exhaled and suffocate on your own waste products. It is most fortunate our digestive system has a seperate intake and exhaust valve. Don't think about that last sentence while eating. |
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ya dude, I was eating while reading your annotation. Thanks for the image |
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My most sincere apologies. |
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What happened to the rotating cylinder!? Havent you ever heard of nitro R/C cars, boats, planes, and helicopters?? |
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On the rotating valve drum Wikd mentioned...
There's two companies currently pioneering that technology. The first is MACRO industries, they have a website, as well as Coates Engineering. They have a website also, all kinds of information on the rotating spherical valve head. Check out www.coatesengine.com to read all about it. |
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WikdWaze, the Superconstellation plane had what were posibly the most complex multiple radial engines
ever, and memory fails me or they were of the rotating cylinder sleeve type you mentioned.
De nada. |
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Switcahble dukct rasingg eingdians .... |
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What is your favorite colour, actually .... :-D-K |
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Mine is red with white polka dots |
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I think the cat's crawling on someone's keyboard again. |
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I dont think most people are really thinking about this. The spherical valve head is by far the greatest idea for the pistoned engine since electronic fuel injection. I take note of the links that TheReverendEric posted. Expand you vision of a valve. The definition of a valve is any device for closing or modifying the passage through a pipe, outlet, inlet, or the like, in order to stop, allow, or control the flow of a fluid media. A poppet valve is only one of a thousand differant valve devices. A single sphere per cylinder would work well, but the dual sphere per cylinder that Coates has designed would out flow and have better volumetric efficiancy than any configuration of poppet valves for any given engine. The power advantages of such a thing are immense as well, with the removal of the camshaft(s),lifters, pushrods, rocker arms/followers, valve keepers/retainers/springs, valves, etc. just the reduction in energy lost through friction and moving parts would make more power. I could go on, but you get the point. I only wish such a thing was available to the public, I'd up grade in a heart beat. If someone would ask me to design the perfect piston engine it would consist of an aluminum block with steel sleeves (for good heat transfer and low weight), steel/or titanium motorcycle type multi piece crankshaft with cylindrical roller bearings on the rod and main journals (light weight, high strienght, and no need for lubrication) titanium rods( weight and stienght),cast aluminum pistons with cast-in ceramic tops (cast pistons don't expand as much allowing for closer tolerances, and the ceramic tops would resist phenominal amounts of heat), roller bearings on the wrist pins (no oil, low friction), distributorless computer controlled ignition (self explanitory), multiport electronic fuel injection (ditto above), and the Coates cylinder head (for reasons mentioned above). Heck, and just for kicks, how about a ball bearing ceramic turbo and air to air intercooler to further increase in power and efficiancy. Does it get any more perfect than that, for a creation that will someday be replaced with power cells, electric motors, or god forbid, cold fusion. This is, of course, from a Machinist/mechanic/idealistic engineer point of veiw, and I say think outside the market. Thanks for reading, |
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I wonder if a spherical valve could also be used to vary the TDC volume of the cylinder between the compression and exhaust strokes. During compression, one wants there to be a certain amount of volume in the cylinder (one can't compress the fuel/air mixture too much or it will detonate, so beyond a certain point reducing TDC volume will reduce power). But during the exhaust stroke one wants to leave as little spent gas in the cylinder as possible. |
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