Wednesday, September 14, 2011

Continuously Variable Transmission (CVT) with instructions

Continuously Variable Transmission is a transmission type that has infinite speed ratio between two ratio limits (maximum ratio and minimum).

The system is based in two cones conected by other element (usually a belt), and moving this element along the cone you can change the transmission ratio in infinite positions.

It doesn't need clutch to change the ratio, but it have a problem, it cann't have reverse, you need add a transmission reserver.

Obviously the maximum allowed torque is limited by the cone connector.

This transmission is very used in scooters and low fuel consumption cars, as the Toyota Prius, because it can keep the engine in the optimal rpm range.

Based in the original desing I had developed a Lego version. In this model de minimum ratio is 1:0.5 and de maximum ratio 1:2

Note: I had use a big linear actuator but the system only need 4-studs displaciment and you can use a mini-LA (I dont have one...)

It uses two opposing cones, with 4-stud maximum diameter and 2-studs minimum.

You can get other limited ratios using other cones size. 

The cone connect element is a 30.4x14 tyre

With this tyre the maximum allowed torque is 4 Ncm, this is a M motor torque, or a XL motor with 1:3 external ratio torque

A little video:

You can see more pictures here:

And download step by step instructions in the INSTRUCTIONS page, enter and access to the Download folder

I hope you like it!!!


Anonymous said...

This is ingenious i would of not thought of that. Are you going to put in a race car? ;)

Anonymous said...

this is awesome

Alien said...

Would it be possible to extend it using this(don't know if the slopes is right):

I suppose it's just going to get very big then.

Alien said...

The back end will have to be this:

Ps the gear box is stunning.

Sheepo said...

I bought this cones some time ago to built this CVT, but when you use 4(2 complete cones) the final size is HUGE. You can't use this in a car...

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