×

System and method for determining clutch gains in a transmission during a power downshift

  • US 8,744,705 B2
  • Filed: 03/15/2012
  • Issued: 06/03/2014
  • Est. Priority Date: 03/15/2012
  • Status: Active Grant
First Claim
Patent Images

1. A method of controlling an offgoing clutch in an automatic transmission during a power downshift of a vehicle having a controller, the method comprising:

  • detecting initiation of the power downshift;

    reducing a pressure command to the offgoing clutch to a threshold level via the controller;

    introducing a calibrated error value to a pressure control command for the offgoing clutch via the controller during the inertia phase of the power downshift;

    calculating a shift energy value of the power downshift only over the inertia phase of the power downshift;

    synchronizing a speed of the offgoing clutch with a speed of an oncoming clutch speed during the torque phase of the power downshift;

    determining a pressure and a clutch torque of the offgoing clutch after a calibrated duration of the synchronizing of the clutch speeds;

    calculating a clutch gain as a function of the offgoing clutch pressure and the offgoing clutch torque;

    recording the calculated clutch gain in a lookup table that is indexed by the calculated shift energy value; and

    controlling a subsequent power downshift of the transmission using the recorded clutch gain.

View all claims
  • 3 Assignments
Timeline View
Assignment View
    ×
    ×