CONTINUOUSLY VARIABLE TRANSMISSIONS, SYSTEMS AND METHODS

• US 20170268638A1
• Filed: 03/17/2017
• Published: 09/21/2017
• Est. Priority Date: 03/18/2016
• Status: Active Grant

• Current Assignee: Fallbrook Intellectual Property Company LLC (Fallbrook Technologies Incorporated)
• Original Assignee: Fallbrook Intellectual Property Company LLC (Fallbrook Technologies Incorporated)
• Inventors: Nichols, Jon M., Sweet, Brian Benjamin, Pohl, Brad P., Thomassy, Fernand A., Elliott, William J., Galvin, David, Dawe, Daniel J.
• Granted Patent: US 10,458,526 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 61/664 Friction gearings
• CPC Class Codes: F16H 61/6646 controlling shifting exclusively as a function of speed

Abstract

Components, subassemblies, systems, and/or methods for improving the performance and increasing the life of continuously variable transmissions (CVT). A first stator may be formed with an outer diameter greater than an outer diameter of a second stator. A stator may have radial slots formed to extend farther radially inward than slots on the other stator. The larger outer diameter of a stator or the formation of guide slots on a first stator extending farther radially inward of guide slots on a second stator may prevent egress of a planet axle from a radial slot, increase range of the CVT, allow for larger tolerances to reduce losses, and other advantages, Slots on a timing plate may be formed having a width greater than a width of guide slots formed on either stator to allow the stators to control adjustments while the timing plate avoids runaway axles. The shape, including junction between surfaces on a timing plate or stator may also prevent an axle from egressing. Any one or a combination of these features allow a CVT to be formed smaller and lighter to allow for clearance in smaller environments and for reduced inertia.

Claims

1. A stator for a continuously variable transmission (CVT) having a plurality of tiltable planet assemblies, each tiltable planet assembly including a planet and a planet axle, wherein tilting the planet axle changes a transmission ratio of the CVT, the stator comprising:

a plurality of guide slots for receiving an end of a planet axle having a diameter, each guide slot comprising;

first and second surfaces for contact with the end of the planet axle, the first and second surfaces separated by a first width to form a desired clearance width based on the diameter of the planet axle; and

a third surface located radially inward of the first and second surfaces for limiting the travel of the end of the planet axle, wherein the radial guide slot is formed having a second width at a radially outward opening, the second width being less than the first width.

2. The stator of claim 1, wherein the second width comprises a protuberance having a radially inward curvature substantially matching the curvature of the planet axle.

3. The stator of claim 1, wherein the third surface is curved.

4. The stator of claim 3, wherein the first surface, the second surface, and the third surface form a continuous surface.

5. The stator of claim 4, wherein the third surface has a radius of curvature substantially equal to a radius of the planet axle.

6. The stator of claim 1, wherein the second width is less than the diameter of the planet axle.

7. A stator assembly for a continuously variable transmission having a plurality of tiltable planet assemblies, each tiltable planet assembly including a planet and a planet axle, wherein tilting the planet axle changes a transmission ratio of the CVT, the stator assembly comprising:

a first stator comprising;

a plurality of offset guide slots for receiving an end of a planet axle having a diameter, each offset guide slot comprising;

first and second surfaces for contact with the end of the planet axle, the first and second surfaces separated by a first width to form a radial opening and to form a desired clearance width based on the diameter of the planet axle; and

a third surface located radially inward of the first and second surfaces for limiting the travel of the end of the planet axle; and

a second stator comprising;

a plurality of radial guide slots for receiving an end of a planet axle having a diameter, each radial guide slot comprising;

first and second surfaces for contact with the end of the planet axle, the first and second surfaces separated by a first width to form a desired clearance width based on the diameter of the planet axle; and

a third surface located radially inward of the first and second surfaces for limiting the travel of the end of the planet axle, wherein the diameter of the first stator is greater than the diameter of the second stator.

8. The stator assembly of claim 7, wherein the radial guide slot is formed having a second width at a radially outward opening, the second width being less than the first width.

9. The stator assembly of claim 8, wherein the second width is less than the diameter of the planet axle.

10. The stator assembly of claim 7, wherein the inner diameter of each radial guide slot in the second stator extends radially inward of the inner diameter of each offset guide slot of the first stator.

11. The stator assembly of claim 7, further comprising a timing plate interposed between a plurality of planets and the first stator, the timing plate having a plurality of timing slots formed by a first timing slot surface and a second timing slot surface.

12. The stator assembly of claim 11, wherein the first stator has an outer diameter greater than an outer diameter of the timing plate.

13. A method for controlling a CVT, comprising:

determining a maximum ratio adjustment rate; and

controlling the ratio adjustment rate to not exceed the maximum ratio adjustment rate.

14. The method of claim 13, wherein controlling the ratio adjustment rate to not exceed the maximum ratio adjustment rate comprises adjusting the ratio at the maximum adjustment rate.

15. The method of claim 13, wherein the step of determining a maximum ratio adjustment rate includes determining the current input speed of the CVT.