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Rather OT....A CVT with gears!
Posted: Sun Dec 08, 2024 10:03 am
by MrGrumpy
Maybe slightly OT, but slightly interesting. Came across this article about a new sort of transmission that's meant to combine the variable ratio of CVT through gears, thus being more efficient.
https://newatlas.com/automotive/geared-cvt-ratiozero/
Don't pretend to understand all the technology, and of course its all just some people's bright idea at the moment, though they are going to fit a prototype to a Tmax as a demonstrator, then try to sell the concept to bike manufacturers. Obviously in principle an interesting idea, but I'm not holding my breath in the expectation of seeing it any time soon!
Re: Rather OT....A CVT with gears!
Posted: Sun Dec 08, 2024 6:20 pm
by Ministerofsillywalks
Just read the article and my brain hurts!
Re: Rather OT....A CVT with gears!
Posted: Sun Dec 08, 2024 6:48 pm
by Andym
Good article but I suspect a mechanical curiosity rather than anything that will become a product you can buy.
Noise, pulsed power delivery and complexity = wear.
Complexity (especially oval gears) = cost
With the current religious orthodoxy requiring electric drive (although my employers are in the process of getting rid of 10000 jobs in that sector) the need for gearing is decreasing. DC motors in particular make simple two and three speed planetary/epicylic gearboxes more likely. If anything I think we'll see even more really basic belt CVT stuff to bodge what they can't make a DC motor do.
Andy
Re: Rather OT....A CVT with gears!
Posted: Sun Dec 08, 2024 7:23 pm
by MrGrumpy
It does look a little complex ie expensive to produce, and the reported 10% gain in efficiency may not be enough to make it attractive. Still its probably cheaper to produce than Honda's DCT let alone the HFT!
Re: Rather OT....A CVT with gears!
Posted: Sun Dec 08, 2024 7:26 pm
by knight2
Andym wrote: ↑Sun Dec 08, 2024 6:48 pm
Good article but I suspect a mechanical curiosity rather than anything that will become a product you can buy.
Noise, pulsed power delivery and complexity = wear.
Complexity (especially oval gears) = cost
With the current religious orthodoxy requiring electric drive (although my employers are in the process of getting rid of 10000 jobs in that sector) the need for gearing is decreasing. DC motors in particular make simple two and three speed planetary/epicylic gearboxes more likely. If anything I think we'll see even more really basic belt CVT stuff to bodge what they can't make a DC motor do.
Andy
I stand to be corrected but i think that's what they are already doing. I seem to vaguely remember an article I read about fitting CVT with electric engines and they seemed to be having a few problems with them. Some body wil be along shortly to put me right
Re: Rather OT....A CVT with gears!
Posted: Mon Dec 09, 2024 10:13 am
by roadster
The interesting thing about this epicyclic gearbox is that the control is entirely mechanical. Toyota hybrids also use an epicyclic gear train to provide a smooth range of gear ratios and they also incorporate the ability to use power from internal combustion and electric motors in proportions determined by software control of electric motor speed/torque.
As pointed out above the trend towards electrical and electronic power trains is not going to change direction any time soon but perhaps the concept might be used for lightweights such as scooters and bicycles.