Automatic transmission and control method of automatic transmission

A control method of an automatic transmission which comprises:

• a first transmission mechanism to which a driving force of a driving source is input through a first clutch and which is configured to switch driving force transmission paths to an output member to establish a first set of gear ratios;
• and
• a second transmission mechanism to which the driving force of the driving source is input through a second clutch and which is configured to switch driving force transmission paths to the output member to establish a second set of gear ratios,
• wherein a one-way clutch is provided in a driving force transmission path that establishes a first certain gear ratio in the first set,
• the first transmission mechanism comprises:
• an input shaft to which the driving force of the driving source is input through the first clutch;
• a first transmission gear provided on the input shaft and configured to establish the first certain gear ratio;
• a plurality of second transmission gears provided on the input shaft and configured to establish remaining gear ratios in the first set;
• and
• a switching mechanism configured to perform engagement and disengagement between the input shaft and the plurality of second transmission gears, and
• a driving transmission direction of the one-way clutch is set such that a rotation inputted from a wheel side to the output member in a predetermined rotational direction is transmitted to the input shaft, the predetermined rotational direction corresponding to a backward movement of a vehicle,
• the control method comprising:
• determining whether a traveling state of the vehicle reaches a predetermined deceleration state;
• and
• upon determining that the traveling state reaches the predetermined deceleration state, executing switching control of causing the switching mechanism to perform the disengagement between the input shaft and the plurality of second transmission gears.