Vehicle automatic transmission control during wheel slip conditions

摘要

It is an object of the present invention to provide a control system for an automatic transmission, which operates so that when slipping of drive wheels is generated at the starting of a vehicle on ice or the like, upshifting from a second gear shift stage to a third gear shift stag is prohibited. However, when the pseudo slipping state of the drive wheels is detected with the locking or unlocking of the drive wheels, the undesirable prohibition of the upshifting of the automatic transmission is avoided. A slip rate of a torque converter is determined on the basis of an engine revolution-speed (a torque converter input rotation-speed) and an automatic transmission input rotation-speed (a torque converter output rotation-speed). When the slip rate exceeds, for example, 102%, so that the driving force is transmitted from the drive wheels toward the engine, it is determined that the pseudo slipping state attendant to the locking or unlocking of the drive wheels has been detected, thereby canceling the prohibition of the upshifting of the automatic transmission.