| 摘要 |
PURPOSE:To perform downshift to enhance the drivability by deciding whether or not the vehicle is in a downshift state wherein the engine brake should be acted on, according to the curved downslope degree of a travel road path, desired deceleration degree and effective downshift degree and according to the result of this decision. CONSTITUTION:During the vehicle travel, a control unit 6 issues an instruction according to the output signals from a throttle opening sensor 7, vehicle speed sensor 8, brake switch 9 and acceleration sensor 10 to thereby control the solenoid valve inside a hydraulic circuit 5 and cause engagement/disengagement of the friction engagement elements of an automatic transmission 2, thereby obtaining a desired speed stage. In this case, the control unit 6 is provided with a curved downslope path downshift decision section 6A. In this section, it is determined, according to the curved downslope degree of a travel road path, driver's desired deceleration degree, and effective downshift degree, whether or not the vehicle is in a downshift state wherein the engine brake should be acted on. When the decision result is YES, an instruction to cause downshift to a speed stage which is one stage lower than the current speed stage is outputted. |
