Containment control for a continuously variable transmission

Patent metadata

Field	Value
Publication number	US-10041589-B2
Application number	US-201514932545-A
Country	US
Kind code	B2
Filing date	Nov 4, 2015
Priority date	May 29, 2012
Publication date	Aug 7, 2018
Grant date	Aug 7, 2018

Abstract

A speed ratio containment process limits the speed ratio of a variator for a CVT for a motor vehicle when rolling backward by commanding a speed ratio that is higher than the actual speed ratio in an overdrive direction. Accordingly, the actual speed ratio moves to a lowest limit, which provides maximum torque when a driver of the motor vehicle steps on the accelerator pedal to resume forward motion of the motor vehicle.

First claim

What is claimed is:

1. A method for speed ratio containment for a motor vehicle continuously variable transmission (CVT) comprising:
detecting an actual speed ratio;
transmitting a command signal to a motor associated with a ratio control subsystem, the ratio control system triggering ratio containment which limits the speed ratio of a variator by commanding a speed ratio that is higher than the actual speed ratio in an overdrive direction, the ratio containment being triggered when the variator reverse direction is detected when the vehicle rolls backwards, the vehicle rolling backwards being sensed by a trunnion pressure sensor that identifies if the ratio control subsystem is behaving as a positive feedback system or a negative feedback system.

2. The method of claim 1 wherein the actual speed ratio moves to a lowest limit, which provides a maximum torque when an accelerator for the motor vehicle is engaged to resume forward motion of the motor vehicle.

3. The method of claim 1 further comprising sensing the variator reverse direction by detecting an output shaft rotation direction.

4. The method of claim 1 further comprising sensing the variator reverse direction by detecting a trunnion's shaft rotation direction.

5. The method of claim 1 further comprising applying an offset to an overdrive direction of the detected actual speed ratio.

6. The method of claim 5 further comprising employing the offset as a command speed ratio.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Xie Zhe
• Neelakantan Vijay A

Classifications

• F16H61/664

  Friction gearings · CPC title

• F16H61/6649 Primary

  characterised by the means for controlling the torque transmitting capability of the gearing · CPC title

• F16H61/6648

  controlling of shifting being influenced by a signal derived from the engine and the main coupling · CPC title

• F16H61/6646

  controlling shifting exclusively as a function of speed · CPC title