Method for controlling rate of change of ratio in a continuously variable transmission

• US 20070142167A1
• Filed: 12/16/2005
• Published: 06/21/2007
• Est. Priority Date: 12/16/2005
• Status: Active Grant

• Current Assignee: FCA US LLC (Stellantis NV)
• Original Assignee: Chrysler LLC (Stellantis NV)
• Inventors: Smith, Jeremy, McGrath, P., Kanafani, Fadi
• Granted Patent: US 7,303,505 B2
• Time in Patent Office: Days
• US Class Current: 477/37
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/107 with endless flexible members
• CPC Class Codes: B60W 2710/0644 Engine speed
• CPC Class Codes: B60W 30/188 Controlling power parameters of the driveline, e.g. determining the required power

Abstract

A method for controlling a rate of change of speed ratios in a continuously variable transmission (CVT) includes sensing a vehicle speed, sensing an engine speed, and sensing a change in a position of an accelerator pedal. The method includes determining a desired engine speed based on said change in said position of said accelerator pedal, said vehicle speed, and said engine speed. The method includes increasing a target engine speed at a first rate to a predetermined value, wherein said target engine speed corresponds to a speed ratio. The method includes measuring a difference between said target engine speed that is held at said predetermined value and an actual engine speed, and increasing said target engine speed to said desired engine speed at a second rate when said difference substantially equals a predetermined threshold, wherein said second rate is less than said first rate.

Claims

1. A method for controlling a rate of change of speed ratios in a continuously variable transmission (CVT), comprising:

sensing a vehicle speed;

sensing an engine speed;

sensing a change in a position of an accelerator pedal;

determining a desired engine speed based on said change in said position of said accelerator pedal, said vehicle speed, and said engine speed;

increasing a target engine speed at a first rate to a predetermined value, wherein said target engine speed corresponds to a speed ratio;

holding said target engine speed at said predetermined value;

measuring a difference between said target engine speed that is held at said predetermined value and an actual engine speed; and

increasing said target engine speed to said desired engine speed at a second rate when said difference substantially equals a predetermined threshold, wherein said second rate is less than said first rate.

2. The method of claim 1 further comprising determining a rate of change of engine speed necessary to attain said desired engine speed.

3. The method of claim 1 further comprising increasing said target engine speed to said predetermined value if a rate of change of engine speed necessary to attain said desired engine speed exceeds a predetermined rate.

4. A system for controlling a rate of change of speed ratios in a continuously variable transmission (CVT), comprising:

a first sensing module that senses a vehicle speed;

a second sensing module that senses an engine speed;

a third sensing module that senses a change in a position of an accelerator pedal; and

a control module that;

determines a desired engine speed based on said change in said position of said accelerator pedal, said vehicle speed, and said engine speed;

increases a target engine speed at a first rate to a predetermined value, wherein said target engine speed corresponds to a speed ratio;

holds said target engine speed at said predetermined value;

measures a difference between said target engine speed that is held at said predetermined value and an actual engine speed; and

increases said target engine speed to said desired engine speed at a second rate when said difference substantially equals a predetermined threshold, wherein said second rate is less than said first rate.

5. The system of claim 4 wherein said control module determines a rate of change of engine speed necessary to attain said desired engine speed.

6. The system of claim 4 wherein said control module increases said target engine speed to said predetermined value if a rate of change of engine speed necessary to attain said desired engine speed exceeds a predetermined rate.