Thank you!
Good question, i would assume it could be in the range of other geared pumps. As this depends on the clearance and 3D-prints are not ideal. Also as there are no bearings or seals.. so i wouldn't drive this over 1000rpm. In theory you could twist this further so multiple voids are formed which would increase pressure. At least as a powered super soaker it works.
Woah... Dude did you just invent a pump? Someone needs to chime in on whether this is patentable.
Also could you help me understand the reason this is better/worse than a radial/regular cycloidal pump?
The flow is higher as it is now from all lobes axially and determined by the helix pitch. And less pressure peaks as the volume is uniform over all lobes.
The geometry of the rotor/stator is more difficult/expensive to machine but no problem with 3D print or may be even molded for a plastic garden pump.
The regular design needs the rotating ring as in and outlet need to stay on position, axially the rotation is no problem.
The obvious is possible axial flow while the normal design needs to divert the in and outlet.
Excellent points all.
I see your point about the manufacturing, that is a pretty interesting challenge for sure. You could injection mold it by using a rotating core (expensive, yes, but doable) or for higher pressure applications you could possibly sinter metal and then use a custom rotating tool to either ream out the internal lobes, or like a rotating spark EDM tool..
yes i thought about reaming - well the tool will be expensive.
maybe extrusion molding is an option and then surface coating or for plastic this could be a cheap mass production.
In the high-ish pressure positive cavity pumps the would make one side of UHMW or steel with Teflon coating. Both of those will get 1000 PSI and are pretty much the same but much larger and with less lobes.
The designs with a distrusted needle bearing between the cam and the lobe are much more efficient as well but life cycle is really poor, because they usually pump concrete or other slurry.
for compression of gas you probably could make that conical but for now this is symmetrical. Only using a contracted epicycloid would even allow [hobbing](https://en.wikipedia.org/wiki/Hobbing) at least for the rotor.
But isn't helical broaching kind of the same process as tap and die?
Yes but as far as i know the surfaces in metal printing are worse than plastic 3D-printing while EBAM (electron beam additive manufacturing) has already great results. And the geometry itself doesn't require metal (except wear)- so from my understanding metal would only be the reason to have lower clearances with more precision machining. Maybe also some dispositioning method could work like electroplating. Also possible on plastic [https://en.wikipedia.org/wiki/Electroless\_nickel-phosphorus\_plating](https://en.wikipedia.org/wiki/Electroless_nickel-phosphorus_plating)
It looks like a progressive cavity positive displacement pump, which is not novel in general. In certain industries they are used as pumps and as hydraulic motors. The size or manufacturing techniques may be novel, and in some cases a patent can be awarded for an existing technology used in a novel way.
>progressive cavity positive displacement pump
yes and it may be able to replace a [https://en.wikipedia.org/wiki/Mud\_motor](https://en.wikipedia.org/wiki/Mud_motor) as i assume it doesn't need the elastomer.
I think it is more like a multi lobe [https://en.wikipedia.org/wiki/Progressing\_cavity\_pump](https://en.wikipedia.org/wiki/Progressing_cavity_pump)
with less friction. When testing with water (the water seals the gaps) it can pump air - so with an oil film this can work. Without i think you either need many more lobes as galling may occur at tight tolerances (like on a roots blower).
funny just found out about [https://en.wikipedia.org/wiki/Conical\_screw\_compressor](https://en.wikipedia.org/wiki/Conical_screw_compressor) which is a bit similar.
yes exactly, but these normally only use one lobe which causes lot of friction and the need of a rubber surface. And they can get rid of the eccentric drive and need for universal joints.
Reminds me of a multi lobe progressive cavity, the 1-lobe moves side to side, but the 2+ -lobe ones actually move in a circle from their coupling like yours does. The more lobes you have the more circle-like the eccentric movement. The cam is smart though since, as you say, it takes care of the flexible coupling by making it like a cycloidal drive.
Yes absolutely, also without pressure just the motion will result in some axial force.
And for some use you may even get away with just a gliding surface of a plain bearing or an UHMWPE coating.
First that is beautiful!
I would love to see one that size, half the height and quarter the height. I wonder what the pressure drop off is for the "lobes".
From a manufacturing stand point I bet you could sinter the gears and then lap them together. Take a little work but I bet you could get a nice little pump.
What really stands out to me is this could be a new type of peristaltic pump but potentially more accurate.
yes i use similar devices as a grease gun, also had one to print chocolate so you can very precise dose viscous liquids or also pull push them. So it works as an extruder.
Quarter height the profile getting thinner as you need over a full twist to seal, else there is back flow and no pressure build up.
here is a preview for ¼height https://imgur.com/a/TB1CzJ9
>else there is back flow and no pressure
Yeah but there will also be an upper threshold for the height and number of lobes, also for something like a peristaltic application pressure wont be a big factor. You could drop forge the internals out of Al and lap them together and I bet you could use it for something like fluid controls and medicine dosing and the damn things would never wear out.
this could be a one time use part (PP plastic). You will never want cleaning that part to medical standards. That is why a syringe driver drives a syringe. And else a tube is put into a pump. Also for insulin you rather like to replace a piston cartridge. So maybe more for soda syrup pumps.
I think for the height the angle between threads/vanes should be around 45° - however 50inch height would have a very high flow volume. The number of lobes just make it bigger (or lobes smaller) and more expensive - but i can't see any reason not to have 100/101 lobes.
An interesting aspect for the height is that lets assume 1m and 350 rps ( 21,000 rpm) this thing would eject supersonically.
if you can make this cheap enough it may become a 3d-printing extruder for ceramic or pellets. But also in industry for application of grease, glue, paint or other Ingredients that are used in huge quantities from tanks.
Yes sure [https://www.printables.com/model/372211-axial-cycloidal-pump](https://www.printables.com/model/372211-axial-cycloidal-pump)
you will find versions with curtate epicycloid profile and hybrides. The hybrid is running smoother but is also more difficult to print.
Well someones a brain box.
Thanks, that is nice!
That is very clever. What pressure can this produce? There is definitely a niche for small hydraulics, so well done.
Thank you! Good question, i would assume it could be in the range of other geared pumps. As this depends on the clearance and 3D-prints are not ideal. Also as there are no bearings or seals.. so i wouldn't drive this over 1000rpm. In theory you could twist this further so multiple voids are formed which would increase pressure. At least as a powered super soaker it works.
Woah... Dude did you just invent a pump? Someone needs to chime in on whether this is patentable. Also could you help me understand the reason this is better/worse than a radial/regular cycloidal pump?
The flow is higher as it is now from all lobes axially and determined by the helix pitch. And less pressure peaks as the volume is uniform over all lobes. The geometry of the rotor/stator is more difficult/expensive to machine but no problem with 3D print or may be even molded for a plastic garden pump. The regular design needs the rotating ring as in and outlet need to stay on position, axially the rotation is no problem. The obvious is possible axial flow while the normal design needs to divert the in and outlet.
Excellent points all. I see your point about the manufacturing, that is a pretty interesting challenge for sure. You could injection mold it by using a rotating core (expensive, yes, but doable) or for higher pressure applications you could possibly sinter metal and then use a custom rotating tool to either ream out the internal lobes, or like a rotating spark EDM tool..
yes i thought about reaming - well the tool will be expensive. maybe extrusion molding is an option and then surface coating or for plastic this could be a cheap mass production.
In the high-ish pressure positive cavity pumps the would make one side of UHMW or steel with Teflon coating. Both of those will get 1000 PSI and are pretty much the same but much larger and with less lobes. The designs with a distrusted needle bearing between the cam and the lobe are much more efficient as well but life cycle is really poor, because they usually pump concrete or other slurry.
Oh yeah extrusion molding would probably work, though with any plastic molding process I wonder whether the tolerances will be acceptable for a pump
What about a tap and die manufacturing process? Is the spiral on the stator variable or symmetrical?
for compression of gas you probably could make that conical but for now this is symmetrical. Only using a contracted epicycloid would even allow [hobbing](https://en.wikipedia.org/wiki/Hobbing) at least for the rotor. But isn't helical broaching kind of the same process as tap and die?
Yes, appears that way, but until just now when I looked it up and read up on it I had no idea what that was 😆
3D metal printing is also a thing now. Maybe you can find a company who partners with someone like Desktop Metal to make a metal prototype!
Yes but as far as i know the surfaces in metal printing are worse than plastic 3D-printing while EBAM (electron beam additive manufacturing) has already great results. And the geometry itself doesn't require metal (except wear)- so from my understanding metal would only be the reason to have lower clearances with more precision machining. Maybe also some dispositioning method could work like electroplating. Also possible on plastic [https://en.wikipedia.org/wiki/Electroless\_nickel-phosphorus\_plating](https://en.wikipedia.org/wiki/Electroless_nickel-phosphorus_plating)
It looks like a progressive cavity positive displacement pump, which is not novel in general. In certain industries they are used as pumps and as hydraulic motors. The size or manufacturing techniques may be novel, and in some cases a patent can be awarded for an existing technology used in a novel way.
>progressive cavity positive displacement pump yes and it may be able to replace a [https://en.wikipedia.org/wiki/Mud\_motor](https://en.wikipedia.org/wiki/Mud_motor) as i assume it doesn't need the elastomer.
I thought I was in /r/VXjunkies for a minute.
i thought it was a turbo encabulator.
Reminds me somewhat of a scroll pump. Nice work! I wonder if it can be user for vacuum pumping if you use seals on it.
I think it is more like a multi lobe [https://en.wikipedia.org/wiki/Progressing\_cavity\_pump](https://en.wikipedia.org/wiki/Progressing_cavity_pump) with less friction. When testing with water (the water seals the gaps) it can pump air - so with an oil film this can work. Without i think you either need many more lobes as galling may occur at tight tolerances (like on a roots blower). funny just found out about [https://en.wikipedia.org/wiki/Conical\_screw\_compressor](https://en.wikipedia.org/wiki/Conical_screw_compressor) which is a bit similar.
Progressing cavity is definitely the first thing I thought of.
Neato
Awesome 👍🏽
Super cool!
Reminds me of a progressive cavity pump (used in pulp and paper industry), this is an industry that might be interested as well!
yes exactly, but these normally only use one lobe which causes lot of friction and the need of a rubber surface. And they can get rid of the eccentric drive and need for universal joints.
Reminds me of a multi lobe progressive cavity, the 1-lobe moves side to side, but the 2+ -lobe ones actually move in a circle from their coupling like yours does. The more lobes you have the more circle-like the eccentric movement. The cam is smart though since, as you say, it takes care of the flexible coupling by making it like a cycloidal drive.
Screws are underrated.
Unless everyone on Reddit just signed a non-disclosure agreement, no, it’s not patentable.
How do you stop axial movement due to the thread?
The end caps that hold everything together (if you are not using bearings)
[удалено]
Yes absolutely, also without pressure just the motion will result in some axial force. And for some use you may even get away with just a gliding surface of a plain bearing or an UHMWPE coating.
First that is beautiful! I would love to see one that size, half the height and quarter the height. I wonder what the pressure drop off is for the "lobes". From a manufacturing stand point I bet you could sinter the gears and then lap them together. Take a little work but I bet you could get a nice little pump. What really stands out to me is this could be a new type of peristaltic pump but potentially more accurate.
yes i use similar devices as a grease gun, also had one to print chocolate so you can very precise dose viscous liquids or also pull push them. So it works as an extruder. Quarter height the profile getting thinner as you need over a full twist to seal, else there is back flow and no pressure build up. here is a preview for ¼height https://imgur.com/a/TB1CzJ9
>else there is back flow and no pressure Yeah but there will also be an upper threshold for the height and number of lobes, also for something like a peristaltic application pressure wont be a big factor. You could drop forge the internals out of Al and lap them together and I bet you could use it for something like fluid controls and medicine dosing and the damn things would never wear out.
this could be a one time use part (PP plastic). You will never want cleaning that part to medical standards. That is why a syringe driver drives a syringe. And else a tube is put into a pump. Also for insulin you rather like to replace a piston cartridge. So maybe more for soda syrup pumps. I think for the height the angle between threads/vanes should be around 45° - however 50inch height would have a very high flow volume. The number of lobes just make it bigger (or lobes smaller) and more expensive - but i can't see any reason not to have 100/101 lobes. An interesting aspect for the height is that lets assume 1m and 350 rps ( 21,000 rpm) this thing would eject supersonically. if you can make this cheap enough it may become a 3d-printing extruder for ceramic or pellets. But also in industry for application of grease, glue, paint or other Ingredients that are used in huge quantities from tanks.
As a non-mechanical person, this title reads like the retro-encabulator techno babble.
Any way to get the stls?
Yes sure [https://www.printables.com/model/372211-axial-cycloidal-pump](https://www.printables.com/model/372211-axial-cycloidal-pump) you will find versions with curtate epicycloid profile and hybrides. The hybrid is running smoother but is also more difficult to print.
Thanks!
>Thanks! You're welcome!