Steuerungssystem für automatisches Kraftfahrzeuggetriebe

摘要

In a system (60) for controlling a gear ratio of a multi-step geared or continuously variable automatic transmission of a vehicle, the gear ratio is determined through fuzzy production rules each having one of the ATF temperature, the steering angle or the engine coolant temperature as a parameter. For example, the rule regarding the ATF temperature defines that the gear position should be shifted down if the ATF temperature is high. With this arrangement, when the ATF temperature is high, the gear position is determined in the downshifting direction so that the amount of torque converter slippage can be reduced, whereby avoiding temperature rise in the transmission. Furthermore, since the engine speed is relatively high at that situation, the motive force would be sufficient even when climbing a hill.