CONTINUOUSLY VARIABLE TRANSMISSION

• US 20150080165A1
• Filed: 11/21/2014
• Published: 03/19/2015
• Est. Priority Date: 07/05/2007
• Status: Active Grant

• Current Assignee: Fallbrook Intellectual Property Company LLC (Fallbrook Technologies Incorporated)
• Original Assignee: Fallbrook Intellectual Property Company LLC (Fallbrook Technologies Incorporated)
• Inventors: Pohl, Brad P., Thomassy, Fernand A., Lohr, Charles B.
• Granted Patent: US 9,869,388 B2
• Time in Patent Office: Days
• US Class Current: 475/186
• CPC Class Codes: F16H 15/28 with external friction surface
• CPC Class Codes: F16H 15/50 Gearings providing a continuous range of gear ratios
• CPC Class Codes: F16H 61/664 Friction gearings
• CPC Class Codes: F16H 61/6648 controlling of shifting being influenced by a signal derived from the engine and the main coupling
• CPC Class Codes: F16H 63/067 mechanical actuating means

Abstract

Inventions are directed to components, subassemblies, systems, and/or methods for continuously variable transmissions (CVT). In one aspect, a control system is adapted to facilitate a change in the ratio of a CVT. A control system includes a control reference nut coupled to a feedback cam and operably coupled to a skew cam. In some cases, the skew cam is configured to interact with carrier plates of a CVT. Various inventive feedback cams and skew cams can be used to facilitate shifting the ratio of a CVT. In some transmissions described, the planet subassemblies include legs configured to cooperate with the carrier plates. In some cases, a neutralizer assembly is operably coupled to the carrier plates. A shift cam and a traction sun are adapted to cooperate with other components of the CVT to support operation and/or functionality of the CVT. Among other things, shift control interfaces for a CVT are described.

Claims

1. A method for controlling a continuously variable transmission (CVT) having a plurality of tiltable planets, the method comprising the steps of:

determining an operating condition for the CVT;

comparing the operating condition of the CVT to a control reference;

determining a rate of change in tilt angle for the plurality of tiltable planets;

determining a tilt angle for the plurality of tiltable planets from the determined rate of change of the tilt angle for the plurality of tiltable planets; and

adjusting the tilt angle for the plurality of tiltable planets based on the determined tilt angle.

2. The method of claim 1, wherein the control reference comprises a parameter associated with the operation of the CVT.

3. The method of claim 2, wherein the control reference comprises one of a desired skew angle, a desired tilt angle for the plurality of tiltable planets, a position reference of a traction sun, a speed ratio, or a torque ratio.

4. The method of claim 2, wherein the control reference is compared to a feedback value.

5. The method of claim 2, wherein the control reference is converted to provide a reference skew angle for the plurality of tiltable planets.

6. A skew-based control system for controlling a continuously variable transmission (CVT) having a plurality of tiltable planets, comprising:

a control reference source configured to provide a control reference indicative of a desired operating condition of the CVT;

a summing junction operable to compare the control reference to a feedback value;

a skew dynamics module operable to

receive a result of the comparison of the control reference to the feedback value, and

return a rate of change in the tilt angle for the plurality of tiltable planets; and

an integrator for determining a tilt angle for the plurality of tiltable planets based on the rate of change in the tilt angle for the plurality of tiltable planets, wherein the system is configured to change the tilt angle of the plurality of tiltable planets.

7. The system of claim 6, wherein the CVT comprises a traction sun, the plurality of tiltable planets operably coupled to a carrier plate and to the traction sun, and wherein the control reference comprises a position reference of the traction sun.

8. The system of claim 6, wherein the control reference comprises one of a desired skew angle, a desired tilt angle, a speed ratio, and a torque ratio.

9. The system of claim 6, further configured to generate a control error based on the comparison of the desired operating condition with a current operating condition.