Man that looks really sweet! Are you famous in Netherlands now?

"Eternal fame" so no. Oh wait another group bet us a crate of beer that we couldn't pump the water in under 2 minutes, we did it in 1:02

And this will be my fifth tv appearance in the Netherlands, I'm more famous than clogs.

I imagine it has to be fairly precise to maintain a seal, without being too large that it would excessively rub against the chamber or whatever.

Does it still operate well if there's a tiny gap between a gear "tooth" and the chamber wall? How well does it hold up to wear? Would small debris damage the chamber walls/gear teeth?

In that order:
A tiny gap is necessary between the lobes and the chamber(and between the lobes) the loss in volume moved is lesser than the friction that would otherwise occur.
Pretty decently so far, the biggest wear points are attaching the lobes to their axles and the Plexiglas bending, which lets water leak into the paper gasket, which then gets filthy. (The Plexiglas was our teacher's idea since he thought it would look cool in section. It does, but before we added the 6 extra bolts it leaked like crazy.)
There's some aluminium dust and quite sizable shavings that I couldn't for the life of me extract from the casing so we just rolled with them. Minor scratches but nothing pumpstopping.

Not shown in the photo are the two gears on the back of the pump, the three lobed things don't mesh like gears but instead always seal in the middle of the pump. They were 3d printed and sanded by hand to make them fit. Not quite what I'd call precision engineering. We tried to hire somebody to cnc mill them from aluminum but he didn't get it done before the deadline.

Also fun fact: one of the six smaller bolts is fake, while drilling the hole the drill bit broke and embedded itself in the casing, not a problem on the intake side so we just left it as is out of fear to damage our irreplaceable part. But that's not something you want a teacher to find out, instead we cut down a bolt and glued the head into the Plexiglas cover.......clever am I right?

SCANDAL

That's one of those funny little details that's gonna make for a great joke when you're doing some speeches about it when you become rich.

It's a bit like how beats headphones have extra metal in them so they weigh more which gives the idea of build quality.

But all in this was a pretty fun project. Still not as cool as last year's "propel this baseball through the hole in that steel plate...........NO EXPLOSIVES" and the year before that's "beer crate robot."

That's a very nice pump design, and from the perspective of expansion would a similar design with more lobes in various arrangements (such as three around a central point) offer any advantage to pump strength or quality?

Like this?

or this


Or do you mean multiple pumps stacked together? In which case I'd refer you to the patent I linked. Another way to achieve a similar, but less effective, result you can make the lobes spiral slightly.

What do you mean by spiral? Do you mean, like, have the top and bottom faces not line up?

Is there a reason that the 3 toothed gears were used? Does having more make it less efficient?

Like this. This is one of our failed projects, the walls all subtly curve inwards and thus don't seal, couldn't quite figure out how to fix that in the CAD model.


When it comes to lobe pumps 2 has the most volume and least amount of friction, but they're a lot harder to seal. 3 fixes the sealing problems and still transports a lot of volume, but has a bit more friction. More lobes after that gives you a higher maximum pressure and a more consistent pressure.

I was actually thinking of neither of those. Currently, your rotational axes are all parallel, which is just fine for two, but couldn't you have three if each one was angled at 120 degrees from one another, and the lobes were rounded to seal it?

Ah okay.
Lets skip 3 gears(because 3 never mesh right) and go straight to four. Then a new problem arises: The casing is an integral part of the pump's design, as the gif in one of my earlier comments shows the water is circulated around the sides of the lobes and the casing forms a seal against them. If 4 were to be placed interlocking like you suggest then none of them would have the opportunity to create a sealed chamber against the casing because they'd all be inter meshing like the 2 are in the middle of a normal pump.
Or am I still missing the point here?

(I spend a really long time trying to figure out a way to make this idea work but I just can't. I'd also totally have taken that patent.)

Suppose a casing was built around this construction (with alterations to the gear design to reduce the number of teeth and make them more lobe-y), then you would have three outer paths for the liquid, correct?

Son of a ♥♥♥♥♥.........

That's right. that might actually work. Probably won't be more effective with the way the drivetrain would have to be constructed and the extra friction it would create. But yes that would in theory work.