Automatic transmission, control method for automatic transmission, and non-transitory computer-readable medium

A control method for an automatic transmission, the automatic transmission including a torque converter disposed downstream of a drive source in a power transmission path and provided with a lockup clutch, and a transmission mechanism disposed downstream of the torque converter and configured to change a speed ratio between an input shaft and an output shaft, the method comprising:

• in a state where the lockup clutch is engaged, starting upshift when a rotation speed of the input shaft reaches a first rotation speed;
• and
• in a state where the lockup clutch is disengaged or slips, starting upshift when the rotation speed of the input shaft reaches a second rotation speed obtained by subtracting a first predetermined rotation speed from the first rotation speed, wherein
• the first predetermined rotation speed decreases as an output torque of the drive source increases.

A non-transitory computer-readable medium storing a program executable by a computer of an automatic transmission, the automatic transmission including a torque converter disposed downstream of a drive source in a power transmission path and provided with a lockup clutch, and a transmission mechanism disposed downstream of the torque converter and configured to change a speed ratio between an input shaft and an output shaft, the program causing the computer to execute:

• a procedure of, in a state where the lockup clutch is engaged, starting upshift when a rotation speed of the input shaft reaches a first rotation speed;
• and
• a procedure of, in a state where the lockup clutch is disengaged or slips, starting upshift when the rotation speed of the input shaft reaches a second rotation speed obtained by subtracting a first predetermined rotation speed from the first rotation speed, wherein
• the first predetermined rotation speed decreases as an output torque of the drive source increases.