New Continuously Variable Transmission

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Discussion Overview

The discussion centers around a new concept for a continuously variable transmission (CVT) that does not rely on friction-based mechanisms. Participants explore the potential efficiency and torque handling of this design, as well as its limitations and practical applications in automotive contexts.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that the proposed CVT could be more efficient and handle higher torques without slippage due to its non-friction-based design.
  • Concerns are raised about the durability of the roller clutch and the oscillation issues in the transmission, with a proposal to use two mechanisms in parallel to cancel out forces.
  • Another participant argues that the current best CVT is Toyota's hybrid synergy drive, which integrates electric motors and planetary gear sets, but questions whether it qualifies as a true CVT.
  • A critical viewpoint is presented, stating that the proposed design is an oscillating 4-bar mechanism that may be limited in speed and efficiency, and may not be suitable for automotive applications.
  • Some participants express skepticism about the practicality of the design, referencing past inventions like the D-Drive that were initially praised but later found to be impractical under load.
  • There is a discussion about the efficiency of friction drives, with differing opinions on their inherent efficiency and practical performance under load.
  • One participant notes that the proposed idea may simply be a variation of existing technologies, referencing a specific adjustable speed drive technology.

Areas of Agreement / Disagreement

Participants express a mix of support and skepticism regarding the proposed CVT design. While some see potential in the concept, others highlight significant limitations and question its feasibility in practical applications. No consensus is reached on the viability of the design.

Contextual Notes

Participants note that the proposed mechanism may require further research and development to address issues such as vibration and durability. There are also references to existing technologies that may overlap with the proposed design.

Who May Find This Useful

This discussion may be of interest to engineers, automotive enthusiasts, and researchers exploring innovations in transmission technology and powertrain systems.

ZenonDorin
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https://www.youtube.com/watch?v=nOzRzmfh884 Unlike other CVTs that use belts or steel balls, this is obviously not friction based therefore it should be more efficient and be able to withstand higher torques without any risk of slippage.

The main problem that must be solved is the trepidation that appears in the transmission. I think that using 2 such mechanisms in parallel working in opposite directions would cancel out the forces generated by the rod movement and by the bearing oscillation.

I'm also not sure about the durability of the roller clutch because it would have to take billions of high torque couplings.

What do you guys think?
 
Engineering news on Phys.org
Here it is, a rough working mechanism to help you better understand the principle :smile:

 
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the best cvt right now is the lasted toyota hybrid synergy drive. Two electric motors, one ICE, two planetary gear sets, no clutches or bands, all gears and bearings
 
I applaud your work but I'm sorry to say this "transmission" won't work for an automotive application. It's an oscillating 4-bar mechanism which would be severely limited in its speed capabilities, vibration concerns, and as you point out the output requires a one way bearing and the output is only being driven half the time.

It will be a clunky, poor excuse for a transmission with gears and drive shafts. Sorry.
 
kevindeschamp said:
the best cvt right now is the lasted toyota hybrid synergy drive. Two electric motors, one ICE, two planetary gear sets, no clutches or bands, all gears and bearings
As far as I know that is not a CVT in itself but rather an integrated power train and it requires a battery to work.
It is a hybrid drive, not a CVT that you would just connect to an ICE and freely adjust the ratio.

Mech_Engineer said:
I applaud your work but I'm sorry to say this "transmission" won't work for an automotive application. It's an oscillating 4-bar mechanism which would be severely limited in its speed capabilities, vibration concerns, and as you point out the output requires a one way bearing and the output is only being driven half the time.

It will be a clunky, poor excuse for a transmission with gears and drive shafts. Sorry.
I know that right now it's not suitable for automotive. But I think it's possible to make it practical if more research is put into it (for which I don't have the money or time, I just wanted to show the potential of such a concept).
Take the IC engine for example. It is a heavily oscillating device and the first engine didn't have too much power density and it was vibrating like hell. Today they are powerful and much smoother.

At the end of the first video I said that 2 such devices could be symetrically coupled so that the vibrations would cancel out (like pistons do in an ICE).
Also, the bearings for the 2 mechanisms would be oriented in different directions then the outputs would be connected through a 1:1 gear system. This way the output would be driven full time, in a wavy manner of course but adding a well designed elastic coupling would smooth the output.
 
ZenonDorin said:
this is obviously not friction based therefore it should be more efficient
A friction drive is not inherently inefficient. It is inefficient only if it does slip.
 
Baluncore said:
A friction drive is not inherently inefficient. It is inefficient only if it does slip.
Not inherently, but in practice they are (about 70% efficiency for belt drive even when it does not slip). Designing them to transmit high torques makes them really inefficient.
 
This isn't a bad idea. However, you really have to see what happens with this under real loads and do a kinematic force analysis. I remember a while back that an Australian named Steve Durnin claimed to have invented a CVT called the D-Drive that didn't use friction, but a complex gearing system. News articles claimed it was the holy grail of power transmission. Turns out some engineers took a look at it later and found out he had created an overdesigned planetary gear system that wouldn't work under any sort of applied load. Afterwards, news articles were printed with headlines that said something like, "So, about that holy grail thing...".

Not saying that this is the same kind of idea, but to really prove the concept there's got to be a more realistic use case than just spinning some wheels or gears in the air. If this were modified to propel a toy car or something with some real weight on it, I'd take it more seriously.
 
True, the whole "D-Drive" mechanism could be reduced to a simple differential where one half is driven by a secondary electric motor which is just a replacement for a friction disc i.e. poor efficiency under useful torque.

Regarding my invention, unfortunately lego technic lacks the components needed to build an automatic ratio changing system so the idea that I would have to stop the car to change the ratio wasn't that exciting to step up from the static concept. Other than that it would work, it can take reasonable loads.
 
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  • #11
Thanks for the heads up!
My video is already more than 1 year old so this technology may actually be a variation of my idea and not the other way. Do you know when those products appeared on the market?
 
  • #12
I'm retired and we used them on paper converting machinery when I was a newly minted engineer . The technology is at least 40+ years old.

AceEngineer
 

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