Build the World's First (patented) Geared CVT [Studio file included]

[Divitis]

I was looking for a CVT for my next project when this came up: 

 

About a year ago an Italian start-up got a patent for a gear based CVT transmission module (however there seem to be earlier implementations of ta very similar system). The video above illustrates its inner workings in detail.

Obviously, I could not resist and had to recreate it. But as I'm spending summer far away from my Lego, all I could produce is the digital model, which you can download here -> https://bricksafe.com/files/divitis/miscellaneous-/CVT.io

Now, do we have a volunteer with a good supply of bricks and time on their hands (I'm looking at you @Auroralampinen) who wants to build it and test it out for the community?

It's a no-motor setup, meaning one has to turn the yellow banana gears by hand, but hopefully it's enough to see if and how this works out with Lego.

Note: The original uses small electric motors to control the displacement of the arms attached to each of the sun gears. I devised a mechanical system to do that, and that's what the black 16t gear which sticks out is for. It controls the displacement of the upper arms through the red differentials. When the diffs are stationary, the blue 12t gear above spins at the same speed as the 28t turntable and the rack doesn't move.

More info available to the brave and the curious :)

[2GodBDGlory]

Wow, that is so cool! I think I saw a headline about that a few months back, and thought it would be super cool to try to realize in Technic. However, I guess I was busy with other stuff, because I never even got around to trying to understand the design in the first place.

I'm super excited to see that you recreated that! I'd love to try a test build of it, but I've only got four of those banana gears, so I'll have to leave that to someone else.

Very nice work!

It brings to mind this design I put together years ago, in that both operate on varying the pivot of a linkage, but the real-world prototype and your design are way more sophisticated! I'm not sure my design is actually a CVT, since there's 16 fixed positions on the output gears, and so some discrete number of teeth has to be advanced in one rotation: https://www.youtube.com/watch?v=gceNC7GKbBQ&ab_channel=2GodBDGloryLegoTechnicVideos

 

[Auroralampinen]

7 hours ago, Divitis said:

I was looking for a CVT for my next project when this came up: 

 

Now, do we have a volunteer with a good supply of bricks and time on their hands (I'm looking at you @Auroralampinen) who wants to build it and test it out for the community?

 

Well, i do have a lot of time because i don't work(bacause of my mental issues) :).

[Divitis]

3 hours ago, Auroralampinen said:

Well, i do have a lot of time because i don't work(bacause of my mental issues) :).

I am sorry to hear. I had no idea and apologies if my comment was inappropriate in any way.

 

7 hours ago, 2GodBDGlory said:

I'm not sure my design is actually a CVT, since there's 16 fixed positions on the output gears, and so some discrete number of teeth has to be advanced in one rotation: https://www.youtube.com/watch?v=gceNC7GKbBQ&ab_channel=2GodBDGloryLegoTechnicVideos

That's an interesting prototype, even though technically you're right that it's stepper operated.
From what I read the problem with ratcheting CVTs is that the output isn't linear. I reckon the four arms inside a planetary gear help with that, but then they further smoothed it out with elliptical gears (not sure how that works but we don't have those in Lego anyway)

 

So, no takers? with 4 diffs, 5 turntables and 16 banana gears laying around? ;)

[PlasticGear]

Incredible ! I was also looking at this mechanism but didn't let it a go. It seems massive.

Can't wait to see it in action ! I am a bit worried tho, since it is an asynchronous mechanism, how it will behave with the lego gear slack.

[Auroralampinen]

5 minutes ago, Divitis said:

I am sorry to hear. I had no idea and apologies if my comment was inappropriate in any way.

 

 Nope it wasn't inappropriate i actually smiled and yes, i have fully accepted this, that i have become a meme, for that i have always a lot time to build lego's😄

 

Edit, i have seen much worse stuff in my life, because i was school bullied, so the bullying ruined my mental health:/

Edited 3 hours ago by Auroralampinen

[Davidz90]

Very interesting! Great job recreating it.

For the real thing, I have some doubts regarding the durability of the ratcheting mechanism in automotive applciations. Nevertheless, this is a really clever solution. 

[Jundis]

1 hour ago, Divitis said:

From what I read the problem with ratcheting CVTs

Thats exactly the point here. To make this work, you need a ratched mechanism that rebound (or whatever the "slipiing back" is called) is near to zero. With Lego bricks, this is nearly impossible to recreate.

Still what a fantastic effort to make a brick version of this beast!