Simkinetics variable speed drive (SIVAT)

[Miles]

Simkinetics IVT:
http://video.google.com/videoplay?docid=-2667394369567824498#

 

[liveforphysics]

Very interesting. I didn't think anyone had made rachet-type CVTs in little packages. I would love to see how he got his torque ripple so low. I thought getting them below 3-5% would require something like 6 seperate cam shafts.

This type was the only sort I had ever seen:

http://www.varibox.com/video/view/10

 

[Geebee]

I hope it comes on the market, unlimited low gears are what I need, I just modded one trike to 96 gears and this would be even better assuming a reasonable efficiency.

 

[lawsonuw]

I'd not be too surprised if this was an "eccentric ratchet" (my own name) CVT combined with a planetary gear set to give it zero speed capability. (i.e. to subtract the input rpm from the CVT's output rpm) An additional output gear would then be used to get any desired top speed inpututput ratio. (1:1 in this case) This link off of Wikipedia is of the general "eccentric ratchet" type, but has been modified to give reduced speed instead of increase speed. (and also add a LOT of complexity...) Another link, but this time based on a roller ramp clutch instead of a ratchet with a crap ton of pawls. (neither of these are the first example I saw of this CVT, but I've since lost the link)

Very interesting. I didn't think anyone had made rachet-type CVTs in little packages. I would love to see how he got his torque ripple so low. I thought getting them below 3-5% would require something like 6 seperate cam shafts.

Wouldn't be surprised if the linked IVT had 30-50 ratchet pawls. (this assumes my guess above is on track)

Lawson

 

[paultrafalgar]

This is "just" a CVT. Surely we need the integration of CVT with motor? Isn't that what this does:
http://www.magnomatics.com/HomePageVideo.aspx
Correct me if I'm wrong.

 

[Miles]

Paul,

The Magnomatics video shows a single ratio geared motor.

Just a CVT? Even if the efficiency is no greater than the Nu Vinci, it's likely that it will be less than half the weight and has an unlimited range...........

 

[paultrafalgar]

Sorry, you are right.
Scratch Magnomatics.
Is not my point valid though, namely, that we would like a CVT combined with a motor?
I am aware that 1) Field weakening and 2) Delta/Wye switching are attempts at this, but is there any other prototype that does CVT and motor drive in the one unit?

 

[Miles]

Delta/Wye isn't even equivalent to a 2 speed transmission. It helps the controller and batteries out and may give a very small efficiency increase at the motor.

Once the technology exists, it won't be a huge problem to integrate it into a motor. Mind you, we don't even have a 2-speed hub motor, yet

 

[lalaland]

Some info below on the SIVAT - I spoke via email to Barry (the inventor) a couple of times about it. He forwarded a document to me (that does'nt contain any proprietary info), but other may also find it interesting...View attachment SIVAT.doc

 

[danielfrance]

Hello,
I recently watched the SIVAT video in youtube. That really made me curious! Definetelly I'd like to see one of that in my bike. But I didn't find more explanations about it. An I couldn't open the document SIVAT.doc that lalaland posted. Word says it is corrupted. I tryed recovering, opening in google docs, nothing worked. Did this happen to anyone else?

 

[TylerDurden]

Server crashed a while back.

Here ya go, folks:

 

[danielfrance]

Thanks a lot!!!

I'm looking forward to see the SIVAT in production...

Have a great week!

 

[Hillhater]

Anybody heard of progress / productionisation of this hub ?
If it can do what is claimed, ...SA, Shimano, Sram etc should all be fighting to sell it ?