US-12618464-B2 - Hardened slot walls in a skew shifting continuous variable planetary system

Abstract

A continuous variable planetary (CVP) system comprises a C2 carrier having a pattern of slots, the slots having one or more slot walls; a C1 carrier, at least one of the C2 carrier or C1 carrier being rotatable relative to the other; at least three planetary assemblies coupled between the C2 carrier and the C1 carrier, each planetary assembly including a planet, a planet axle, and an end cap on at least one end of the planet axle, the end cap disposed within the slot, rotation of C2 carrier relative to the C1 carrier inducing a skew condition in the planet axle and thereby inducing a tilt condition on the planet axle; and a protective layer affixed against at least one of the one or more slot walls, the protective layer including one or more protective layer attachment features configured to attach to one or more slot wall attachment features.

Inventors

• Brad Pohl
• Siddhesh Ozarkar

Assignees

• ENVIOLO B.V.

Dates

Publication Date

20260505

Application Date

20241125

Claims (20)

1. 1 . A carrier of a continuous variable planetary (CVP) system, the CVP system including at least one planet assembly having a planet, a planet axle about which the planet rotates, and an end cap on one end of the planet axle, the carrier comprising: a slot including one or more slot walls, at least a portion of at least one of the one or more slot walls having a contour, the one or more slot walls having one or more slot wall attachment features, the slot configured to receive the end cap and to allow the end cap to move therein as the planet axle skews and tilts under operating conditions; and a protective layer conforming to the contour of the at least a portion of the at least one of the one or more slot walls, the protective layer including one or more protective layer attachment features configured to attach to the one or more slot wall attachment features to secure the protective layer against the at least a portion of the at least one of the one or more slot walls within the slot, the protective layer configured to protect the at least one of the one or more slot walls from damage caused by movement of the end cap within the slot as the planet axle skews and tilts under the operating conditions.
2. 2 . The carrier of claim 1 , wherein the protective layer is metallic.
3. 3 . The carrier of claim 1 , wherein the protective layer is made from a ferrous alloy.
4. 4 . The carrier of claim 1 , wherein the protective layer is made from steel.
5. 5 . The carrier of claim 1 , wherein the protective layer is made from carbon steel.
6. 6 . The carrier of claim 1 , wherein the carrier is rotatable.
7. 7 . The carrier of claim 1 , wherein the carrier is non-rotatable.
8. 8 . The carrier of claim 1 , wherein the at least one of the one or more slot walls is flat.
9. 9 . The carrier of claim 1 , wherein the at least one of the one or more slot walls is curved.
10. 10 . The carrier of claim 1 , wherein the one or more protective layer attachment features comprise one or more tabs, and the one or more slot wall attachment features comprise one or more pockets.
11. 11 . The carrier of claim 10 , wherein the one or more tabs include bent portions.
12. 12 . The carrier of claim 10 , wherein the one or more tabs includes curved portions.
13. 13 . The carrier of claim 10 , wherein the one or more pockets include a pocket at a bottom of the at least one of the one or more slot walls.
14. 14 . The carrier of claim 10 , wherein the one or more pockets include an open pocket through to a back side of the carrier.
15. 15 . The carrier of claim 1 , wherein the carrier comprises magnesium.
16. 16 . The carrier of claim 1 , wherein the protective layer comprises a metallic layer with a thickness of between 0.05 mm and 0.3 mm.
17. 17 . The carrier of claim 1 , wherein the at least one of the one or more slot walls includes only a rear slot wall.
18. 18 . The carrier of claim 1 , wherein the at least one of the one or more slot walls includes only a front slot wall.
19. 19 . The carrier of claim 1 , wherein the one or more slot wall attachment features comprises a clip.
20. 20 . The carrier of claim 1 , wherein the protective layer is manufactured with pliant materials capable of being conformed to the contour of the at least a portion of the at least one of the one or more slot walls.

Description

PRIORITY CLAIM This application is a continuation application of U.S. Nonprovisional application Ser. No. 18/220,191, entitled “HARDENED SLOT WALLS IN A SKEW SHIFTING CONTINUOUS VARIABLE PLANETARY SYSTEM,” filed on Jul. 10, 2023, which claims benefit of and hereby incorporates by reference U.S. provisional application Ser. No. 63/359,524, entitled “HARDENED SLOT WALLS IN A SKEW SHIFTING CVP,” filed on Jul. 8, 2022, by inventors Brad Pohl et al., and further incorporates by reference U.S. Pat. No. 11,174,922. TECHNICAL FIELD This invention relates generally to systems and methods for protecting carriers to maintain a transmission ratio in a continuous variable planetary (CVP) system. BACKGROUND A continuously variable planetary (CVP) system is a specific type of continuously variable transmission (CVT) used in vehicles such as bicycles, trucks and aircraft and in machines such as turbines. In a CVP system, transmission ratios and torque are controlled via an assembly of rotating and tilting spherical planets operating between input and output rings of a transmission. In some embodiments, the planets are held in place by two carriers. Rotation of one carrier relative to the other results in skew, which is counteracted by tilting of the planets. Such tilting results in change of contact diameters between the planets and the input and output rings. The different contact diameters result in different speeds at which the input and output rings rotate, which effectively controls the transmission ratio of the transmission. When the input ring contacts the planets at positions with larger contact diameters than the output ring, the input ring will spin more quickly than the output ring, indicative of an underdrive condition. Similarly, when the output ring contacts the planets at positions with larger contact diameters than the input ring, the output ring will spin more quickly than the input ring, indicative of an overdrive condition. Thus, tilting of the planets controls the transmission ratio, as well as the torque ratio. SUMMARY The inventors herein have recognized that, over time, mechanical contact and/or interaction between components in a continuously variable planetary (CVP) system results in material wear and tear, which has been found to cause deterioration in the range of transmission ratios available to the CVP. One particular interaction on a skew-shifting CVP, namely, the interaction between the planet axles and the carriers that support them, has been determined to cause significant wear and shorten the lifespan of the CVP. In the skew-shifting CVP, when the two carriers are rotated relative to each other, the planets and planet axles are caused to skew, causing a first interaction between the planet axles and the slots of the two carriers. The skew induces the planets and planet axles to tilt. Tilting of the planet axles causes another interaction between the end caps and the slots of the two carriers. These interactions have been found to cause wear primarily to the slot walls, which has been found to cause a reduction in the range of planet tilt and thus a reduction in the range of transmission ratios available. Further, metallic particles shed from the carriers due to the mechanical wear contaminates the traction fluid, which causes further degradation of other CVP components exposed to the traction fluid, such as other rolling contacts. To mitigate or eliminate mechanical abrasion of the slot walls, embodiments include a protective (e.g., metallic or other wear or wear-resistant) layer positioned between the slot walls of the carriers and the end caps. In some embodiments, the protective layer may be affixed to each of the slot walls, possibly on the forward-facing slot wall and/or rear-facing slot wall of each slot of each carrier. In some embodiments, the protective layer may be positioned on only the forward-facing slot wall or only on the rear-facing slot wall of all of the slots of one or both carriers. In some embodiments, the protective layer may be a substantially thin mechanical element. In some embodiments, the protective layer may be formed from metallic material, such as a ferrous alloy. In some embodiments, the protective layer may be formed from steel such as carbon steel, hardened steel with higher carbon content, mild steel, or stainless steel. In some embodiments, the protective layer may be affixed, retained, and/or bonded to the slot wall. In some embodiments, the protective layer may be affixed or retained using mechanical attachment features. The mechanical features may include one or more protective layer attachment features such as appendages, protrusions, extensions, or tabs (hereinafter “tabs”) that are configured to secure the protective layer to the slot wall. The mechanical features may include one or more slot wall attachment features, such as a pocket (open or closed), groove, cavity, recess, indentation, conduit, ridge, clip, or other opening. In some embodiments,