Continuously variable transmission
Traction planets and traction rings can be operationally coupled to a planetary gearset to provide a continuously variable transmission (CVT). The CVT can be used in a bicycle. In one embodiment, the CVT is mounted on the frame of the bicycle at a location forward of the rear wheel hub of the bicycle. In one embodiment, the CVT is mounted on and supported by members of the bicycle frame such that the CVT is coaxial with the crankshaft of the bicycle. The crankshaft is configured to drive elements of the planetary gearset, which are configured to operationally drive the traction rings and the traction planets. Inventive component and subassemblies for such a CVT are disclosed. A shifting mechanism includes a plurality of pivot arms arranged to pivot about the centers of the traction planets as a shift pin hub moves axially.
1. A continuously variable transmission for integrating within a frame of a bicycle, comprising:
a planetary gear set comprising a planet carrier coupled to a set of planet gears, the planet carrier configured to receive a torque input from a set of cranks and a sun gear, wherein rotation of the planet gears drives the sun gear; and
a variator, comprising
a plurality of tiltable traction planets arranged about a crankshaft of the bicycle, each tiltable traction planet positioned between an input ring and an output ring, the input ring being coupled to the sun gear, and
a cage having an input cage and an output cage, wherein each of the input cage and the output cage comprises a plurality of slots, and wherein the plurality of slots of the input cage are angularly offset relative to the plurality of slots of the output cage.
2. The continuously variable transmission of claim 1 , wherein the output ring is integrated with a support structure for the variator.
3. The continuously variable transmission of claim 2 , wherein the support structure for the variator is integrated with a frame member of the bicycle.
4. The continuously variable transmission of claim 3 , wherein a housing of the continuously variable transmission forms part of a bottom bracket of the bicycle.
5. The continuously variable transmission of claim 1 , wherein the planet carrier is connected to the input cage, and wherein torque is supplied to the variator from the sun gear and the planet carrier.
6. The continuously variable transmission of claim 1 , wherein the cage is fixed to the frame, and wherein torque is supplied to the variator through the input ring.
7. A bicycle, comprising:
a plurality of frame members;
a planetary gear set comprising a planet carrier coupled to a set of planet gears, the planet carrier configured to receive a torque input from a set of cranks and a sun gear, wherein rotation of the planet gears drives the sun gear; and
a variator, comprising
a plurality of tiltable traction planets arranged about a crankshaft of the bicycle, each tiltable traction planet positioned between an input ring and an output ring, the input ring being coupled to the sun gear, and
a cage having an input cage and an output cage, wherein each of the input cage and the output cage comprises a plurality of slots, and wherein the plurality of slots of the input cage are angularly offset relative to the plurality of slots of the output cage.
8. The bicycle of claim 7 , wherein the output ring is integrated with a support structure for the variator.
9. The bicycle of claim 8 , wherein the support structure for the variator is integrated with a frame member of the bicycle.
10. The bicycle of claim 9 , wherein a housing of the continuously variable transmission forms part of a bottom bracket of the bicycle.
11. The bicycle of claim 7 , wherein the planet carrier is connected to the input cage, and wherein torque is supplied to the variator from the sun gear and the planet carrier.
12. The bicycle of claim 7 , wherein the cage is fixed to the frame, and wherein torque is supplied to the variator through the input ring.