Vehicle: Car: Transmission: Continuously Variable
2 Disk C.V.T.   (+5)  [vote for, against]
A continually variable transmission with two disks, and two wheels.

There would be two disks with a vertical shaft that will allow the disks to rotate in opposite directions. Between the two disks would be two wheels, one connected to an input shaft, and other on the opposite side of disks, connected to an output shaft. The two wheels will be connected to two tracks, one on either side of the disks’ shaft, and be able to slide forward or backward along their shafts, in unison. To change the ratio of the transmission, the two disks will move slightly left or right horizontally in relation to the drive shafts, this will offset the center diameter of the disks from the drive shafts, causing the wheels to move forward or back depending which way the disks moved and which way the shafts are rotating. When you aren’t changing the ratio of the transmission, the two wheels would be locked in place. A reverse gear would also be connected to the input shaft.

It would probably need to use a viscous fluid for traction.

This would probably work best with a regular torque converter. Or it could probably work with a clutch instead.


The disks could be able to gradually separate so that they wouldn’t be in contact with the wheels, or move towards each other, creating a clutch like effect.

The shaft between the disks could be removed, and the two wheels could move separately using linear actuators. The wheel on the output shaft could then slide to the opposite side of the disks near the center, reversing the rotational direction of the output shaft, creating a low reverse “gear”, which would make this transmission an I.V.T.

Tell me what you think, but please don’t be mean about it.
-- BJS, Jun 24 2006

http://usera.imagec...iergisz/2_disc_CVT/ illustrations [xaviergisz, Jun 25 2006] good overview of CVT [xaviergisz, Jun 25 2006]

This is another old one. Friction is the big problem. But you seem to have thought of some of the variations.
-- baconbrain, Jun 25 2006

Good link, I think I'm going to build a Lego CVT now.
-- BJS, Jun 25 2006

As long as the viscous liquid is treacle or custard, otherwise it's just all torque and no action.

It also needs to leak, to relieve the idea of being as dry as an old fart. (local colloquialism, or has it become international?)
-- xenzag, Jun 25 2006

Baked and under constant development. Friction coefficients between the driving and driven members are the limiting factors, but Nissan and others are working on this. Snapper lawnmowers had this exact design as recently as the mid-eighties; Dixon lawnmowers used a variation in the seventies that permitted two output shafts that didn't necessarily even go the same direction.

A big plus of this concept is that the overall available ratio is huge, it can be on the order of 6:1 or even more. The available space for the driving members is the limiting factor here, but hey, that's already enormous. That's comparable to a good automatic including the torque converter amplification. The more space-efficient designs don't use a disc but a pair of discontinuous toroidal member, and the transferring wheels between simply pivot rather than slide back and forth.

Google "toroidal CVT" and "disc CVT" and you'll find plenty.
-- elhigh, Jun 27 2006

One major advantage of this idea is that the wheels don't slide sidways on the gripping surface, like most similar designs do.
-- BJS, Jun 27 2006

random, halfbakery