Infinitely variable transmissions, continuously variable transmissions, methods, assemblies, subassemblies, and components therefor
Inventive embodiments are directed to components, subassemblies, systems, and/or methods for infinitely variable transmissions (IVT) having a variator provided with a plurality of tilting spherical planets. In one embodiment, a variator is provided with multiple planet arrays. In another embodiment, a hydraulic system is configured to control the transmission ratio of the IVT. Various inventive idler assemblies and planet-pivot arm assemblies can be used to facilitate adjusting the transmission speed ratio of an IVT. Embodiments of a transmission housing and bell housing are adapted to house components of an IVT and, in some embodiments, to cooperate with other components of the IVT to support operation and/or functionality of the IVT. Various related devices include embodiments of, for example, a control feedback mechanism, axial force generation and management mechanisms, a control valve integral with an input shaft, and a rotatable carrier configured to support planet-pivot arm assemblies.
1. A continuously variable transmission (CVT), comprising:
an input shaft coupled to a power source;
a first variator and a second variator coupled to the input shaft, wherein each of the first variator and the second variator comprises
an array of planets angularly positioned about a longitudinal axis of each variator, each planet rotatable about a planet axle, wherein tilting of the array of planets produces a ratio shift in the respective variator,
a first traction ring and a second traction ring in contact with the array of planets, and
an idler located radially inward of, and in contact with, the array of planets;
a differential mechanism positioned between the first variator and the second variator; and
an output shaft for coupling to a power load.
2. The CVT of claim 1 , wherein the differential mechanism is configured to allow the first variator to rotate at a different ratio than the second variator.
3. The CVT of claim 1 , further comprising a center cam assembly positioned between the first variator and the second variator, the center cam assembly comprising:
first and second torque transfer rings;
first and second cam rings interposed between the first and second torque transfer rings;
first and second cam roller retainers interposed between the first and second cam rings;
a center cam base interposed between the first and second cam roller retainers; and
a synchronization ring interposed concentrically between the first and second cam rings and the first and second torque transfer rings, wherein the synchronization ring inhibits relative rotation between the first and second cam rings.
4. The CVT of claim 1 , further comprising a center assembly comprising:
a centering coupling riding on a carrier;
a center output transfer element coupled to the first traction ring and the second traction ring via a first load cam and a second load cam; and
a drive output element coupled to the center output transfer element.
5. The CVT of claim 4 , wherein the centering coupling comprises a set of splines for coupling the centering coupling to the first traction ring and the second traction ring.
6. The CVT of claim 5 , wherein the center output transfer element comprises a set of splines for coupling the center output transfer element to the drive output element.
7. The CVT of claim 1 , further comprising an input cam assembly configured as an axial force generation system.
8. The CVT of claim 7 , wherein the axial force generation system comprises a hydraulic axial force generation system and a cam-based axial force generation system.
9. The CVT of claim 8 , wherein the hydraulic axial force generation system comprises a cam load piston configured to apply an axial force to one of the first traction ring and the second traction ring.
10. The CVT of claim 8 , wherein the cam-based axial force generation system is configured to provide an axial force that exceeds a maximum required operational axial force, and wherein the hydraulic axial force generation system is configured to apply a desired axial force.
11. The CVT of claim 10 , wherein the hydraulic axial force generation system is configured to reduce an axial force.
12. The CVT of claim 11 , wherein the hydraulic axial force generation system comprises an unloader piston configured to reduce an axial force applied to one of the first traction ring and the second traction ring.
13. The CVT of claim 1 , wherein one traction ring for each of the first variator and the second variator is fixed rotationally.
14. The CVT of claim 13 , wherein the first traction ring is fixed rotationally.