CVT- Continuously Variable Transmission
CVTs only provide positive ratios.
IVTs (Infinitely Variable
Transmissions) provide a full range of ratio from
reverse, through stationary, and from extremely low speeds, up to high
A planetary gear set (epicyclic) can be used to convert a CVT intoa IVT by power split.
The planetary gear set "subtracts some RPMs" from the CVT output. Thus, the overall ratio spread can be freely customized.
The planetary gear set formula:
WP × (DR + DS) = WR × DR - WS × DS
(W: angular velocities; D: primitive diameters)
Note: in this page, the ratios are calculated as: input speed/output speed.Therefore, ratios are greater than one when speed reduces. And negative ratiosare used when the rotation sense is inverted.
What will be the IVT output speed?
(Win = engine speed ; Rcvt = CVT ratio)
What will be the IVT overall ratio?
( ratios are input speed/output speed )
|Some existing examples of transmissions
( Remark: this page is not intended forexperts because it is just a personal opinion. )
[created: 01 Jul 2003, updated: 19 Set 2008 ] [ designed by vb.web.pt ]