Patent ID: 7294092
Filing Date: 2007-11-13
Classification: B60W,F16H,Y02T,Y10T

Abstract:
1. In an automatic transmission for producing multiple gear ratios between an input and output and having a torque converter that includes an impeller driveably connected to an engine, and a turbine hydrokinetically coupling the impeller to the input, a method for controlling a coasting downshift to a target gear during a coast condition comprising the steps of: (a) determining a target engine speed for the downshift, the target engine speed being a synchronous turbine speed for the target gear at the current vehicle speed; (b) allowing the engine speed to decrease to an idle speed while coasting; (c) disengaging an off-going control element and engaging an oncoming control element while executing the downshift; (d) allowing the turbine speed to increase during the downshift; (e) increasing the engine speed to the target engine speed during the downshift; (f) decreasing the engine speed to the idle speed; and (g) completing the downshift to the target gear.