A New Take On The Cycloidal Drive (Extremely Compact)
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- čas přidán 18. 10. 2019
- I recently designed a Cycloidal drive that takes up a fraction of the foot print of a standard system while maintaining the same level of gear reduction.
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This is really neat!
What you have designed is a kind of differential gear, thats why the gear-ratio calculation is different from a two-stage gear. The first stage (1/10) and the second stage (1/9) are coupled at the input shaft; and by coupling them at the disks as well, you are getting the difference at the output: 1/10-1/9= -1/90. (During one input rotation, one stage moves 1/10 while the other moves 1/9 in the opposite direction.)
I have seen differential gears designed with planetary gears, and some with cycloidal gears by fixing the two disks together. Your solution balances the the two disks, which is much better. Kudos!
You made a cycloidal split ring gearbox, nice! This principle is usually a planetary gearbox design and was invented for compact radar gearboxes
Awesome work man! This is indeed known as a two stage cycloidal drive. I saw a 3 stage one somewhere on CZcams that was nearly 1000:1 using this concept. Great design work!
Not the first to come up with this as a device, but you did an excellent job displaying the concept. The only thing presentation wise that would have been nice to show would be an exploded assembly view of it. Also, if you wanted to continue with an increased compact reduction, you can take this design concept and offset 120 degrees rather than 180 and make it a 3 stage reducer. The only thing with that though is the ability to back drive is diminished, and you start to pick up a little bit of backlash throughout the device just because of gear to lobe clearance that you need in real life. But good job on your drawing, now get out in the shop and build a physical one.
Who was the first came up with that -
And by what name does it come? I'd definitely want to see the evolved version.
It’s frequently called a hypocycloid on CZcams. Commercially you can buy it under the Onvio Dojen product name.
This has been done before, but your specific execution of it is interesting. It is definitely something that would be cool to 3D print as a project.
Really cool man
Awesome! I came up with a similar mechanism where the two discs are glued together, but it's kind of useless due to the vibration. This pin system is much better. The reduction formula for this family of mechanisms is 1 minus the ratio of the ratios. That is, 1 - (top disc lobes / top ring pins) / (bottom disc lobes / bottom ring pins)
So the closer the top and bottom ratios are to eachother, the more reduction you get.
very cool !!
It sounds like the minimal difference in mass could easily be compensated by leaving some cavities in the heavier part. This is a brilliant design, but I wonder how much additional bulk would have to be added to bring it from the ideal design, to a practical one?
i tried making one of these and for some reason the output rotation is not smooth, it rotates as a wave; so it looks as if its rotating in steps. is there a reason for this? the input is smooth as butter, as is the 2nd stage input..
Nice.
The math is simple: rotation 1 is 1/10 of shaft. rotation 2 is 1/9 of shaft in opposite direction. Subtract one from the other (1/9)-(1/10) = 1/90. [ fractional math: multiply top and bottom of both fractions to get same bottom, ie 10/90 and 9/90, then do subtraction of the tops (10-9)/90 ]
Nice work, I've been working toward something like this myself, though with the purpose of removing the need for the drive pins. see James Bruce's comment and my reply
did you end up exploring this further?
there would be vibration because it would vibrate on the transverse axis of the axis or something like that. it would be wobling. int a twisting way.
Are there 2 gears for dynamic balancing ?
How about torque? will the pins able to hold the strength?
Great work man! Do you have Patreon?
I'm definitely not at that stage of my CZcams career, but I appreciate your support.
@@LeviJanssen i ve even think about to register at patreon to support you
Hi, If i am looking to make a cycloidal actuator with a 50:1 ratio. To reduce the vibration, I want to use 2 cycloidal gears, with 50 teeth each. Will this work? Or will there be no output?
Yes, you can do it. Also, you can buy Sumitomo cycloidal transmission on eBay and have fun with that.
Those narrow pins coupling the two cycloidal disks will not be able to withstand the great torque that the cycloidal teeth could deliver.
Balancing this is not as simple at just having the same cross sectional area in the two gears (if made of the same material) as the disks are at different 'heights' or positions axially there will be a torque introduced in a plane parallel to that axis even if perpendicularly no or little torque would be induced.
There's basically the same thing here: czcams.com/video/SH46bpe1cNA/video.html
The difference is that you are using counter-wobbling internal gears (to stop the vibration), whereas the internal gears are fused in the linked video.
Wouldn't the 2 holes cause the disk to snap in 2?
is this still reverse drive
able?
Very Nice, Is this back-drivable?
I can’t say exactly, but I think it should be. Especially if all your contact surfaces are bearings.
I build one like that, but with bearings and housing and I'm using it on an electric bike. Works like a charm.
so the most important thing is to balance the two disk?I'm not sure how to achieve it,could I just make the two disk the same weight ?
I just saw another video about 2 stage cycloidal gear which was 3D printed .But the difference is he makes the top less lobe disk and the bottom one as one piece, he just dosen't use pins and holes like you says in this vedio.I'm curious about the designs between you guys, thank if you could reply.(⁎⚈᷀᷁ᴗ⚈᷀᷁⁎)
jooke huang
vi-de-o
so make it. I want to see it.
link to the model? I want to make it and test it.
The input ring goes to the first gear...
Shouldn't that be driving a ring to drive an output gear?🤔
(Like, flip the output ring and gear)
Or is that aesthetic? Feels like torque is usually put ring to gear at each stage. I'm not a mech either🤷♀️
This reminds me of a Chinese windlass.
Closest I've see is this video, which has a very similar differential-rate reduction with two sets of pins:
czcams.com/video/cnJCWX2nr4M/video.html
Yours is different in that the center lobes are offset for balance, but I do worry about the stacked tolerances vs a rigid center "lobe-set".
agreed, the fixed lobe-set in the centre seems better. I feel the weak-point of the standard cycloid gear is the output drive pins, and the single lobe-set addresses this. Balance can be restored without using a second offset gear-set by adding rotating offset weight directly to the motor shaft.
I was close to this idea myself, thinking of a concentric system where the second gear is inside the offset gear and meshing with a second set of internal lobes, so the whole lot is in one plane.
This kind of stuff breaks my brain. I just don't understand how you get that compounded reduction when both gears are being driven by the same shaft at the same speed.
think of a lever. you need two inputs (a pivot and a driver) to drive an output. in the case of a differential, the pivot is moving. in his design the input shaft is the moving pivot, and the pins from the lower gear are the driver. their difference drives the output (the topmost ring).
maybe you could call it a compound cycloidal drive?
isn't it basically a harmonic drive?
thought about it two...
nice work!
A harmonic drive uses a flexible gear driven by an elliptical bearing.
Cycloidal drives use round gears with an offset axis.
This looks exactly like like what you conceptualized: czcams.com/video/m9eIEVO4kRo/video.html (from Aug 8 2019, so 2 months older, by @Hyesung Ji)
7:39 make patent you find out if thats done or is it counted same lol make final product demo that lift car with using nema17. millions coming lol