Automatic transmission and method for controlling same

摘要

The automatic transmission includes a first friction engagement element which is engaged when a first gear position is realized and disengaged when a second gear position is realized, a second friction engagement element which is engaged when the second gear position is realized and disengaged when the first gear position is realized, and a controller. The controller causes the second friction engagement element to slip by decreasing an instructional pressure for the second friction engagement element while running in the second gear position, and learns an engagement start pressure of the first friction engagement element based on a change in a differential rotation of the second friction engagement element, or in a parameter that changes in accordance with the differential rotation, at a time when an instructional pressure for the first friction engagement element is increased during the slip.

主权项

1. An automatic transmission mounted on a vehicle, comprising:
a first friction engagement element that is engaged when a first gear position is realized, and is disengaged when a second gear position is realized; a second friction engagement element that is engaged when the second gear position is realized, and is disengaged when the first gear position is realized; a shift determination unit configured to determine whether or not a current state is a state in which the automatic transmission does not perform shift, the state involving a predetermined vehicle operation state and an engaged state of one of the friction engagement elements; a learning permission determination unit configured to determine that learning is permitted if the shift determination unit determines that the current state is the state in which the shift is not performed; and a learning control unit configured to, if the learning permission determination unit determines that the learning is permitted, cause the one of the friction engagement elements to slip by decreasing an instructional pressure for the one of the friction engagement elements, and learn an engagement start pressure of the other one of the friction engagement elements based on a change in a differential rotation of the one of the friction engagement elements, or in a parameter that changes in accordance with the differential rotation of the one of the friction engagement elements, at a time when an instructional pressure for the other one of the friction engagement elements is increased.