Half a croissant, on a plate, with a sign in front of it saying '50c'
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Make mine a double.

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flywheel piston

instead of converting a linear motion into a circular motion, just start with circular motion
  (+1, -3)
(+1, -3)
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It's a flywheel with three dome pieces on it that are sealed in a circular combustion chamber around the edge of the flywheel. When the dome pieces reach a sertain spot in their rotation they trigger the combustion that is directionalized into the concave dome. The flywheel is attached directly to the drive shaft. I don't know too much about engines, but I know that this is similar to how some steam turbines work. And they function at a very high efficiency.
xcpostman, Jun 05 2004

How Rotary Engines Work http://auto.howstuf...m/rotary-engine.htm
[Ouroborus, Jun 01 2006]

Scroll Compressor http://en.wikipedia...i/Scroll_compressor
You meant scroll compressor. You saw this idea on the inventing companies site. [pashute, Mar 18 2008]

Tri-Dyne http://www.deadbeat...iptoid/tridyne.html
As mentioned in an annotation. [Vernon, Mar 21 2008]

Tri-Dyne http://books.google...tri-dyne%22&f=false
Actual July 1969 article in Popular Science [Vernon, Mar 08 2010]


       Provided the ports are in the right place, you've got yourself an engine, but first thoughts are that you have no way of compressing the mixture because the 'domes' follow each other around the chamber at a constant distance - and so it's pretty hard to see how it will be efficient. Will withhold bun/bone until some more expert commentary appears
ConsulFlaminicus, Jun 05 2004

       not sure, but isn't this idea the same as a rotary engine? a picture might help, but that's what i got from your description. (link).
xclamp, Jun 05 2004

       [BB] As I imagine it from the description by the idea poster, I think it will 'work', but the thing will not be efficient, may leak combustion product and pressure all over the place, will probably be hard to balance and would sound like a hippo with gas (phut phut phut phut phut phut phut phut phut....)   

       [xcpostman] if you will allow me to clarify to [BB] and [xclamp] what the idea is? Please let me know if it's wrong...   

       Imagine a heavy disc - the flywheel. Around the circumference of the flywheel, and sealed, but not fixed, to it is a tube with a roughly circular cross section. The tube is almost complete except for a slit which runs around its inner side, against the flywheel. It is through this slit that the connectors for the 'pistons' (more correctly 'vanes')attach to, and drive, the flywheel. In operation, the flywheel spins, driven by the vanes inside the donut shaped cylinder, which remains stationary.   

       The pistons do not reciprocate, oscillate or any othere 'ate than rotate, so the two links to the rotary engines are not relevant (sorry). The engine is analogous in many ways to a water wheel with round buckets attached - just imagine the bucket line encased in a tube, and explosive expansion of gases being the driving force rather than water cascading onto buckets in series.   

       Does this help to envisage things?
ConsulFlaminicus, Jun 05 2004

       thanks for elaborating [ConsulFlaminicus] i don't know enough to be able to guess how well this would work, as i can't envision exactly where the exhaust escapes the engine -- but (+) for thinking outside of the piston and arriving at this design [xcpostman] with limited knowledge of engines (but obviously with more than i have!).
xclamp, Jun 05 2004

       Thanks for elaborating and describing my idea better than I could ConsulFlaminicus. What you said was dead on.   

       As for what xclamp mentioned about the exhaust. The Cylinder around the wheel can have a cut out that the exhaust can expelled through. And instead of having 2 dome pieces have three to create a seal so there is no flame shooting into it.
xcpostman, Jun 05 2004

       The valve arrangement is going to be the main hurdle, given that the vanes/pistons are in the same chamber - the issue is how to ensure driving pressure on each vane/piston is not communicated back as retarding pressure on the following vane/piston.   

ConsulFlaminicus, Jun 05 2004

       [BB] The slit in the tube is hard against the flywheel and is 'sealed' - this is the least of the problems faced.   

       You are confusing 'mass' with 'force' in your turbine analogy - in the proposed motor, the force comes from explosive expansion of a fuel-air vapour mixture. The fact that there does not seem to be a way of compressing the gas first doesn't mean that the igniting mixture wouldn't expand in the tube and exert force on the vanes/pistons - the issue is whether some kind of valve arrangement can be arrived at that stops the pressure also retarding the progress of the next following vane/piston.
ConsulFlaminicus, Jun 06 2004

       I have added a straight portion to the outside of the tube that is an extension of the combustion chamber. All of the force will be toward the concave dome. The other two chambers have open exhaust valves so that they do not retard the motion. Will that will help?
xcpostman, Jun 06 2004

       [xcpostman] You've lost me there little buddy. I think we have reached a point where you really need to post a diagram or flash animation.
ConsulFlaminicus, Jun 06 2004

       [WYbloke], that link has nothing to do with this idea.
ConsulFlaminicus, Jun 07 2004

       Not sure if I understand your concept as described. Doesn't the Wankel rotary engine already behave in this manner?
Ouroborus, Jun 01 2006

       This is not much like a rotary engine or a wankel engine. I came across something very similar to this but can't find the link now. It had a torus with a slit around the inside, in which ran two disk-shaped pistons. There was a narrow gap in the torus which was intercepted by one of another pair of disk-shaped vanes just after the piston passed, thus preventing the retarding pressure on the following piston.   

       (edit) Actually, it was more complicated, now that I think about it. There was a pair of large disks, each with a piston shaped (i.e. circular) hole, which rotated at different rates so the holes lined up with each other and with the piston just at the right moment to let the piston through.
spidermother, Jun 01 2006


       You've just invented the wankel engine
kinemojo, Jun 01 2006

       [kinemojo] suggest you read the idea and the annos. It's nothing like the wankel.
ConsulFlaminicus, Jun 01 2006

       This is definitely NOT a Wankel engine... please remove the M-F-D.
zigness, Jun 01 2006

       [pashute] His idea is nothing like a scroll expander.   

       However, [pashute]'s link does show a very promising way to compress the charge, you'd need 3 of them though or one geared to a 3:1 ratio.   

       Now all you have to do is get around the fact that pressure works in all directions and doesn't care what shape your vanes are, they will be pushed backwards and forwards equally.   

       One very promising way of overcoming this was proposed by [Vernon] as a rotary stirling.
marklar, Mar 19 2008

       See link. [xcpost] right this is what you were thinking of? In 1992 this type of motor was "re-invented". According to Wikipedia, a motor of this sort (as apposed to a compressor) is called: a "scroll expander". I have not found any information on why scroll expanders are not in use, or what their disadvantages are. Also it seems no small scale "scroll expanders" have ever been developed. All existing scroll expanders and compressors are heavy duty, very large machines.
pashute, Mar 19 2008

       It seems to me that the thing described here is not self-consistent. I know of two different engines, each of which have similarities to what is described here. One is the "Tri-Dyne", featured in the July 1969 issue of Popular Science. I'll add a link; it has a central rotor with three dome pieces on it.   

       The other I've never seen posted on the Internet, but I also haven't looked for it; it was old even in 1969. This engine has four curved pistons inside a donut-shaped raceway. I'll call them 1, 2, 3, and 4, going around the raceway. They don't all move at the same speed around the raceway; I think they were connected as opposite pairs (1 & 3, and 2 & 4). When one piston (#2) catches up with another (#1), then #4 is also catching up with #3. There is a special connection between the pairs that ensures one pair catches up to the other always at the same places along the raceway. Those places are fully equipped to allow either fuel intake or fuel exhaust or sparking to occur. Combustion causes the piston #1 to pull away from #2. #2 doesn't stop moving, though, and its connected partner (#4) passes the exhaust port--while #3 passes a fuel intake port. Fresh mixture can be sucked in as this piston pulls away from #4. Meanwhile, in FRONT of #1 it is either compressing a different fuel-air charge, or it is exhausting a spent charge (and in front of #3, it is doing whatever #1 isn't).   

       A truly weird rotary engine.
Vernon, Mar 21 2008

       [Vernon] No - this is nothing like the Tri-Dyne.   

       OK, I think the best way to describe this is to begin by picturing a wind vane - one of those little spinning devices with three scoops mounted radially on a spindle. Now picture the spindle becoming massive. Now picture the circular area of space swept by the moving scoops as being enclosed in a tube - this is the engine cylinder proposed. The drive shaft is connected directly to the centre of the flywheel, as an extension of the axis of rotation, perpendicular to the plane of motion of the domed 'pistons'.   

       Once you see what [xcpostman] is talking about, it becomes really obvious. However, we've now had several years of misinterpretations. The poor bugger must think we are all a bit dim.
ConsulFlaminicus, Mar 21 2008

       I see what the suggestion is, thanks to [CF]'s many explanations. I think it would work, too - just not efficiently. Incidentally, I don't think the seal between the "cylinder" and the flywheel is required - once the gas has been directed into the vanes and reversed, thus transferring the maximum amount of energy, it should be allowed to leak out between the cylinder and the flywheel.
david_scothern, Mar 21 2008

       This is a thrust/mass engine, not a pressure engine. It is essentially an air motor with the compressed gas source provided by combustion rather than a separate compressor.   

       Each combustion event is directed against the back of the dome, and transfers momentum to it. Any attempt to utilize pressure in this situation would result in a balanced force against both vanes.
MechE, Mar 08 2010


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