SYSTEMS AND METHODS FOR CONTROLLING ROLLBACK IN CONTINUOUSLY VARIABLE TRANSMISSIONS

• US 20180347693A1
• Filed: 08/13/2018
• Published: 12/06/2018
• Est. Priority Date: 01/15/2016
• Status: Active Grant

• Current Assignee: Fallbrook Intellectual Property Company LLC (Fallbrook Technologies Incorporated)
• Original Assignee: Fallbrook Intellectual Property Company LLC (Fallbrook Technologies Incorporated)
• Inventors: Thomassy, Fernand A., Lohr, Charles B., Pohl, Brad P., Jackson, David Brian
• Granted Patent: US 10,920,882 B2
• Time in Patent Office: Days
• CPC Class Codes: B60W 10/108 Friction gearings
• CPC Class Codes: B60W 2510/1005 Transmission ratio engaged
• CPC Class Codes: B60W 30/18027 Drive off, accelerating from standstill
• CPC Class Codes: B60W 30/18036 Reversing
• CPC Class Codes: F16H 15/28 with external friction surface
• 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 61/66 specially adapted for continuously variable gearings control of exclusively fluid gearing F16H61/38
• CPC Class Codes: F16H 61/664 Friction gearings

Abstract

A continuously variable transmission capable of operating in a forward direction or reverse direction may be controlled in the reverse direction by providing an initial skew angle in a first skew direction, followed by a set or sequence of skew angle adjustments in an opposite direction to prevent runaway or other unintended consequences. A continuously variable transmission may include a timing plate to maintain all planets at an angle or within a range of an angle in forward and reverse operations.

Claims

1. A method for controlling rollback in a continuously variable transmission (CVT) by a control system comprising a controller communicatively coupled to a sensor configured to sense a first operating parameter of the CVT, the control system further comprising an actuator configured to change a second operating parameter of the CVT, the method comprising:

sensing the first operating parameter of the CVT; and

sending a command to the actuator to adjust a speed ratio of the CVT based on the sensed first operating parameter and a direction of rotation of the CVT, wherein if the CVT changes direction of rotation, sending a command to the actuator comprises;

sending a first command to the actuator to cause a first adjustment of the CVT;

sensing a rate of change of the first operating parameter based on the first adjustment; and

sending a second command to the actuator to cause a second adjustment of the CVT to maintain the rate of change of the first operating parameter constant.

2. The method of claim 1, wherein the second command is sent based on the sensed first operating parameter.

3. The method of claim 2, wherein the first operating parameter comprises a speed ratio and the second operating parameter comprises a tilt angle or a skew angle.

4. The method of claim 2, wherein the first operating parameter comprises a tilt angle and the second operating parameter comprises the tilt angle or a skew angle.

5. The method of claim 1, wherein sensing the rate of change of the first operating parameter based on the first adjustment is performed when the CVT is rotating in a reverse direction of rotation.

6. A system for controlling rollback in a continuously variable transmission (CVT), comprising:

a controller communicatively coupled to a sensor configured to sense a first operating parameter of the CVT; and

an actuator configured to change a second operating parameter of the CVT, wherein the controller comprises a set of instructions configured to;

send a first command to the actuator to cause a first adjustment of the CVT;

sense a rate of change of the first operating parameter based on the first adjustment; and

send a second command to the actuator to cause a second adjustment of the CVT to maintain the rate of change of the first operating parameter constant.

7. The system of claim 6, wherein the second command is sent based on the sensed first operating parameter.

8. The system of claim 7, wherein the first operating parameter comprises a speed ratio and the second operating parameter comprises a tilt angle or a skew angle.

9. The system of claim 7, wherein the first operating parameter comprises a tilt angle and the second operating parameter comprises the tilt angle or a skew angle.

10. The system of claim 6, wherein sensing the rate of change of the first operating parameter based on the first adjustment is performed when the CVT is rotating in a reverse direction of rotation.