Apparatus for controlling concurrent releasing and engaging actions of frictional coupling devices for shifting vehicle automatic transmission

摘要

An apparatus for controlling an automatic transmission of a motor vehicle wherein two hydraulically operated frictional coupling devices are released and engaged, respectively, to effect a clutch-to-clutch shift-up action of the transmission, and a shift-up boundary line for determining whether the shift-up action should take place is compensated by a learning shift-point compensating device, so as to prevent a rise of the vehicle engine above an upper limit during the shift-up action effected according to the compensated shift-up boundary line, the apparatus including an inhibiting device for inhibiting an operation of the learning shift-point compensating device if an amount of overshoot of the engine speed detected during the shift-up action is larger than a predetermined threshold. The apparatus may further includes a pressure compensating device for compensating a releasing pressure of the above-indicated one frictional coupling device, and a compensating coordinating device for controlling one of the shift-point and hydraulic pressure compensating devices depending upon an effect achieved or expected to be achieved by the other compensating device.