Patent ID: 8515631

Claim:
A control device of an automatic transmission for a vehicle, comprising: a vehicle speed detecting section configured to detect vehicle speed; an engine load detecting section configured to detect an engine load; a travel resistance calculating section configured to calculate travel resistance of the vehicle; an uphill gradient calculating section configured to calculate estimated uphill gradient of the vehicle; a driving force margin calculating section configured to calculate a driving force margin of the vehicle on the basis of the engine load, the vehicle speed, the travel resistance and the estimated uphill gradient; an automatic gear shifting section configured to determine a gear via a gear mechanism on the basis of predetermined gear shifting characteristics at least from the detected vehicle speed and the engine load to carry out automatic gear shifting; a manual gear shifting signal outputting section configured to output a manual gear shifting signal indicating a shift up instruction or shift down instruction by a driver of the vehicle; a manual gear shifting section configured to carry out, in response to the manual gear shifting signal outputted from the manual gear shifting signal outputting section, gear shifting from the gear determined on the basis of the predetermined gear shifting characteristics in accordance with the shift up instruction or shift down instruction; a shift mode switching section configured to switch an operation between an automatic shift mode by the automatic gear shifting section and a manual shift mode by the manual gear shifting section and setting the operation to either the automatic or the manual shift mode; and an automatic down shifting section configured to generate automatic down shift when the vehicle speed detected by the vehicle speed detecting section becomes lower than a vehicle speed on an automatic down shift vehicle speed table set up in accordance with the determined gear when the operation is set to the manual shift mode with the shift mode switching section, wherein the automatic down shifting section corrects the automatic down shift vehicle speed table so as to shift to a high vehicle speed side or low vehicle speed side in accordance with the magnitude of the driving force margin of the vehicle calculated by the driving force margin calculating section; wherein the gear mechanism is coupled to a torque converter; and wherein the control device is configured to suppress a rise in temperature of the torque converter as a result of the generated automatic down shift.