CONTROL DEVICE FOR FOUR-WHEEL DRIVE VEHICLE WITH AUTOMATIC TRANSMISSION

PURPOSE:To secure durability desirable even with large load acting upon a friction element during four-wheel drive by setting the speed change time during four-wheel drive shorter than that during two-wheel drive to perform oil pressure control at the speed change time of an automatic transmission. CONSTITUTION:Whether or not two-wheel drive is selected is discriminated by 2-4 switching mechanism 7. At the time of two-wheel drive, the target speed change time T is set to the set time T1. At the time of four-wheel drive, the oil temperature of an automatic transmission A is discriminated, and the target speed change time T is set to T2 at the normal time when the oil temperature is less than the set value. In this case, the target speed change time T2 at the time of four-wheel drive is set shorter than the target speed change time T1 at the time of two-wheel drive. The target speed change time T3 under high oil temperature is set shorter than the target speed change time T2 under normal temperature. A duty solenoid valve is then controlled in such a way that the actual speed change time becomes the target speed change time T1, T2 or T3.