Transmission control to avoid gain switch during shift

Patent metadata

Field	Value
Publication number	US-10408342-B2
Application number	US-201715726988-A
Country	US
Kind code	B2
Filing date	Oct 6, 2017
Priority date	Oct 28, 2016
Publication date	Sep 10, 2019
Grant date	Sep 10, 2019

Abstract

In a transmission hydraulic control system, a gain control valve may be used to switch between a low gain and a high gain based on line pressure. Line pressure may be controlled as a function of turbine torque. If the gain of a holding element or oncoming element changes during a shift as a result of changing turbine torque, shift quality may degrade. If the gain is set low at the beginning of the shift, the controller limits engine torque to ensure that the line pressure is not increased beyond a level that would cause a gain switch. If the gain is set high at the beginning of a shift, the controller maintains the line pressure high enough to prevent a switch to low gain, even if turbine torque drops.

First claim

What is claimed is:

1. A powertrain control method comprising:
between shifts, setting a line pressure as a function of a turbine torque wherein the turbine torque exceeding a threshold results in a line pressure that triggers a gain control valve to increase a shift element gain; and
in response to the turbine torque being less than the threshold at a beginning of a shift, limiting an engine torque throughout the shift to maintain the turbine torque below the threshold.

2. The powertrain control method of claim 1 further comprising:
in response to the turbine torque being greater than the threshold at the beginning of the shift, maintaining the line pressure high enough throughout the shift to maintain the gain control valve at the increased shift element gain level.

3. The powertrain control method of claim 1 wherein the shift element gain is associated with a shift element that is in an engaged state throughout the shift.

4. The powertrain control method of claim 1 wherein the shift element gain is associated with an oncoming shift element for the shift.

Assignees

• Ford Global Tech Llc

Inventors

• Zhang Jianping
• Choi Jaewon
• Morrison Kendrick
• Cicala Stephen Michael
• Laroche Cory Benson

Classifications

• F16H2059/147

  Transmission input torque, e.g. measured or estimated engine torque · CPC title

• B60W2050/0008

  Feedback, closed loop systems or details of feedback error signal · CPC title

• F16H61/061 Primary

  using electric control means · CPC title

• B60W30/19

  Improvement of gear change, e.g. by synchronisation or smoothing gear shift · CPC title

• B60W10/115

  with planetary gears · CPC title