Method of power-on downshifting of automatic transmission interrelated with temporary torque down of engine

摘要

In a downshifting of an automatic transmission with an engine being generally maintained in a substantial power generating condition in a vehicle, the output torque of the engine is decreased by an amount prior to a substantial establishment of a torque transmitting route in the automatic transmission for a shifted down speed stage, and then the output torque of the automatic transmission is repetitively monitored at a certain small scanning cycle after the start of establishing the torque transmitting route in the automatic transmission for the shifted down speed stage, while the monitored output torque of the automatic transmission is repetitively compared with a target value determined therefor at the scanning cycle, thereby progressively recovering the output torque of the engine at the scanning cycle by an amount corresponding to the repetitive comparison of the monitored output torque of the automatic transmission with the target value determined therefor so as to cancel a difference in each comparison.