In general, the simpler a thing is, the better. That doesn’t appear to apply to engines, though, at least not how we’ve been building them. Pistons, cranks, valves, and seals, all operating in a synchronized mechanical ballet to extract useful work out of some fossilized plankton.
It doesn’t have to be that way, though, if the clever engineering behind this wobbling disk air engine is any indication. [Retsetman] built the engine as a proof-of-concept, and the design seems well suited to 3D printing. The driven element of the engine is a disk attached to the equator of a sphere — think of a model of Saturn — with a shaft running through its axis. The shaft is tilted from the vertical by 20° and attached to arms at the top and bottom, forming a Z shape. The whole assembly lives inside a block with intake and exhaust ports. In operation, compressed air enters the block and pushes down on the upper surface of the disk. This rotates the disc and shaft until the disc moves above the inlet port, at which point the compressed air pushes on the underside of the disc to continue rotation.
[Resetman] went through several iterations before getting everything to work. The main problems were getting proper seals between the disc and the block, and overcoming the friction of all-plastic construction. In addition to the FDM block he also had one printed from clear resin; as you can see in the video below, this gives a nice look at the engine’s innards in motion. We’d imagine a version made from aluminum or steel would work even better.
If [Resetman]’s style seems familiar, it’s with good reason. We’ve featured plenty of his clever mechanisms, like this pericyclic gearbox and his toothless magnetic gearboxes.
That’s two moving parts
Watching the video, it seems the motor wastes a lot of the compressed air for such little speed.
Probably could be made a lot better with non-3d printed parts, better surface finish, maybe some seals.. But that would be a lot more work
Was just gonna say, the biggest reason for engines/motors being complex is efficiency. Pros and cons
The interesting question there is how well it would do when it is under a heavy load – if the seal of the wobble disk to casing is good enough it might be a very very high torque engine for the input (quite a bit of surface area for the pressure to work against), and that would make it more efficient in those conditions than most motors. Though you might also need a flywheel to keep it going or a few out of phase wobbly things to keep applying power through the crossover point for it to run at all under a load.
Something very similar is used in aerospace and such, because it can be a VERY high power-to-weight-ratio actuator. Not particularly efficient, but sometimes strict weight and volume limits force tradeoffs in absolute efficiency…
This is just a really weird inefficient turbine. Of course there’s no valves, because it’s a turbine.
That’s how gas and water meters measure the flow speed with a magnet driving an external counter
I see two moving parts (the nutating disc seems to rotate relative to the shaft inside)
It’s just a degenerate propeller with very low torque
This motor is not particularly efficient, but it IS positive displacement, so is commonly used in water meters: https://www.badgermeter.com/products/meters/nutating-disc-flow-meters/disc-series-meters/
Isn’t this similar to the air bearings used in lare model Titan misiles?
Apparently this type of engine is very power dense. So high power in a small package.
https://ntrs.nasa.gov/api/citations/20060056193/downloads/20060056193.pdf
There’s something extremely charming about it. Well done, I look forward to more.
Would it be possible to use the concept in a rotary valve in a piston engine ?
Reminds me of the Dake Square Piston Steam Engine made in Grand Haven, Michigan
http://www.douglas-self.com/MUSEUM/POWER/squarepiston/square.htm
I love the research and testing, especially of the sealing to see if what the idea works.
But, by tilting the disc even further until it is totally aligned with a normal straight axis it becomes a two bladed paddle wheel. Adding a few paddles, like 4, it effectively becomes normal little paddle wheel. And then I would guess it’s more efficiënt, but then again testing is key, and that’s nicely done in the video.