Continuously variable transmission
View Patent ↗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 being configured for receiving a torque input from a set of cranks,
a fixed ring gear, and
a sun gear coaxial with a crankshaft of the bicycle, wherein rotation of the planet gears drives the sun gear; and
a variator, comprising
an input ring coupled to the sun gear via an axial force generation mechanism comprising a cam loader having a set of bearings in contact with a set of ramps,
a plurality of tiltable traction planets arranged about the crankshaft of the bicycle, each tiltable traction planet being in contact with the input ring,
an output ring gear, operationally coupled to the plurality of traction planets and coaxial with the crankshaft of the bicycle,
a cage, and
an idler in contact with the plurality of tiltable traction planets.
2. The continuously variable transmission of claim 1 , wherein the output ring gear is integrated with a support structure for the variator.
3. The continuously variable transmission of claim 1 , wherein the planet carrier is connected to the cage, and wherein torque is supplied to the variator from the sun gear and the planet carrier.
4. The continuously variable transmission of claim 1 , wherein the cage is fixed to the frame, wherein torque is supplied to the variator through the input ring.
5. The continuously variable transmission of claim 1 , wherein a housing of the continuously variable transmission forms part of a bottom bracket.
6. A bicycle, comprising:
a frame;
a continuously variable transmission forming part of the frame, the continuously variable transmission comprising
a planetary gear set comprising
a planet carrier coupled to a set of planet gears, the planet carrier being configured for receiving a torque input from a set of cranks,
a fixed ring gear, and
a sun gear coaxial with a crankshaft of the bicycle, wherein rotation of the planet gears drives the sun gear; and
a variator, comprising
an input ring coupled to the sun gear via an axial force generation mechanism comprising a cam loader having a set of bearings in contact with a set of ramps,
a plurality of tiltable traction planets arranged about the crankshaft of the bicycle, each tiltable traction planet being in contact with the input ring,
an output ring gear, operationally coupled to the plurality of traction planets and coaxial with the crankshaft of the bicycle,
a cage, and
an idler in contact with the plurality of tiltable traction planets.
7. The bicycle of claim 6 , wherein the output ring gear is integrated with a support structure for the variator.
8. The bicycle of claim 6 , wherein the planet carrier is connected to the cage, wherein torque is supplied to the variator from the sun gear and the planet carrier.
9. The bicycle of claim 6 , wherein the cage is fixed to the frame, and wherein torque is supplied to the variator through the input ring.
10. The bicycle of claim 6 , wherein a housing of the continuously variable transmission forms part of a bottom bracket.