CONTINUOUSLY VARIABLE TRANSMISSION

• US 20180195586A1
• Filed: 02/26/2018
• Published: 07/12/2018
• Est. Priority Date: 08/26/2008
• Status: Active Grant

• Current Assignee: Enviolo BV
• Original Assignee: Fallbrook Intellectual Property Company LLC (Fallbrook Technologies Incorporated)
• Inventors: Thomassy, Fernand A.
• Granted Patent: US 10,704,657 B2
• Time in Patent Office: Days
• CPC Class Codes: F16H 15/28 with external friction surface
• CPC Class Codes: F16H 15/503 in which two members co-operate by means of balls or rollers of uniform effective diameter, not mounted on shafts
• CPC Class Codes: F16H 15/52 in which a member of uniform effective diameter mounted on a shaft may co-operate with different parts of another member
• CPC Class Codes: F16H 55/32 Friction members
• CPC Class Codes: Y10T 29/49464 Assembling of gear into force transmitting device

Abstract

Components, subassemblies, systems, and/or methods for continuously variable transmissions (CVT) having a control system adapted to facilitate a change in the ratio of a CVT are described. In one embodiment, a control system includes a stator plate configured to have a plurality of radially offset slots. Various traction planet assemblies and stator plates can be used to facilitate shifting the ratio of a CVT. In some embodiments, the traction planet assemblies include planet axles configured to cooperate with the stator plate. In one embodiment, the stator plate is configured to rotate and apply a skew condition to each of the planet axles. In some embodiments, a stator driver is operably coupled to the stator plate. Embodiments of a traction sun are adapted to cooperate with other components of the CVT to support operation and/or functionality of the CVT.

Claims

1. A continuously variable transmission (CVT) comprising a main shaft defining a main drive axis and a plurality of traction planets arranged around the main drive axis, each traction planet comprising a planet axle defining a tiltable axis of rotation, the CVT comprising:

a first stator plate comprising a plurality of radially offset slots arranged angularly in a first plane about a center of the first stator plate coaxial with the main drive axis of the CVT, wherein a first end of each planet axle is positioned in a radially offset slot; and

a second stator plate comprising a plurality of radial slots, the plurality of radial slots arranged angularly about a center of the second stator plate coaxial with the main drive axis of the CVT wherein a second end of each planet axle is positioned in a radial slot, and wherein the first stator plate is configured for rotation relative to the second stator plate.

2. The CVT of claim 1, wherein the second stator plate is non-rotatable about the main drive axis of the CVT.

3. The CVT of claim 1, wherein each radially offset slot has a curved profile in a second plane perpendicular to the first plane defined by the first stator plate.

4. The CVT of claim 3, wherein the first stator plate is formed with a clearance cut.

5. The CVT of claim 4, further comprising a shift stop extension arranged about the center of the first stator plate.

6. The CVT of claim 5, wherein the shift stop extension is located radially inward of the radially offset slots.

7. The CVT of claim 5, wherein the shift stop extension is located radially outward of the radially offset slots.

8. The CVT of claim 1, further comprising a control system configured to rotate the first stator plate relative to the second stator plate to an angular displacement ((β

) to induce a non-zero skew angle (ζ

) to tilt the axles of the traction planets to a unique tilt angle (γ

) to control an operating condition of the CVT.

9. The CVT of claim 8, wherein the operating condition is a speed ratio.

10. The CVT of claim 8, wherein the control system comprises a microprocessor communicatively coupled to a look-up table used to convert a value of angular displacement to an actuator command signal.

11. The CVT of claim 10, wherein the actuator command signal comprises a voltage or current.

12. The CVT of claim 10, wherein the microprocessor is configured to control the CVT using an open loop scheme.

13. The CVT of claim 10, wherein the actuator command signal comprises a change in a position of a cable.

14. A method of controlling a continuously variable transmission (CVT) comprising a main shaft defining a main drive axis and a plurality of traction planets arranged around the main drive axis, each traction planet comprising a planet axle defining a tiltable axis of rotation, a first end of each planet axle being positioned in a radially offset slot in a first stator and a second end of each planet axle being positioned in a radial slot in a second stator, the method comprising:

rotating the first stator relative to the second stator to an angular displacement (β

) to induce a non-zero skew angle (ζ

) to tilt the axles of the traction planets to a unique tilt angle (γ

).

15. The method of claim 14, wherein a control system including a microprocessor performs:

receiving a desired speed ratio (SR) set point for the CVT;

determining the angular displacement for the CVT; and

determining, from a look-up table, an actuator command signal based on the determined angular displacement.

16. The method of claim 15, further comprising determining the actual SR for the CVT.

17. The method of claim 16, wherein measuring the actual SR of the CVT comprises measuring a speed of an input component and an output component of the CVT.

18. The method of claim 16, wherein measuring the actual SR of the CVT comprises measuring a tilt angle of a planet axis of rotation.

19. The method of claim 16, wherein measuring the actual SR of the CVT comprises measuring a torque of one or more of an input component and an output component.

20. The method of claim 16, performed as an open loop process.