Patent ID: 7627411

Claim:
A control apparatus for a step-variable automatic transmission of a vehicle having an engine operatively connected to the step-variable automatic transmission, said control apparatus comprising: a target-drive-force-related-value setting portion operable to set a target-drive-force-related value corresponding to a target drive force of the vehicle; a target-throttle-valve-angle calculating portion operable to calculate a target opening angle of a throttle valve of the engine for obtaining an output of the engine to realize the target-drive-force-related value in a present speed position of said step-variable automatic transmission; a shift control portion operable to determine a shifting action of the step-variable automatic transmission on the basis of said target opening angle of the throttle valve, a vehicle-speed-related value, and stored shift boundary lines which are predetermined so as to provide a predetermined amount of hysteresis between a determination of a shift-up action between two speed positions of the automatic transmission and a determination of a shift-down action between said two speed positions, and to effect said shifting action; a shift determining portion operable to determine as to whether to effect the shifting action of the step-variable automatic transmission to the present speed position, on the basis of the target opening angle of the throttle valve in the present speed position, the vehicle-speed-related value, and said shift boundary lines; and a shift permitting portion operable to permit the shifting action of said step-variable automatic transmission back to a previous speed position prior to a previous shifting action to the present speed position, via said shift control portion on the basis of the target opening angle of the throttle valve in said present speed position and said vehicle-speed-related value, if said previous shifting action to the present speed position was determined by said shift determining portion on the basis of the target opening angle of the throttle valve in the present speed position, the vehicle-speed-related value, and said shift boundary lines.