| 摘要 |
A downshift control device for an automatic transmission is provided in which the transmission is shifted down by releasing an oil pressure from a first engaging element that has been engaged while applying an oil pressure to a second engaging element that has been released. This downshift control device includes an applied pressure control actuator for controlling a pressure to be applied to the second engaging element, by supplying a pressurized oil to a back pressure chamber of an accumulator provided in an oil path to the second engaging element, and removing the pressurized oil from the back pressure chamber. This control actuator receives a first command to supply the pressurized oil to the back pressure chamber from the time when a downshift command is generated to a predetermined time or the time when a detected gear ratio starts being changed, and then receives a second command to remove the pressurized oil from the back pressure chamber until the detected gear ratio reaches a predetermined gear ratio just before completion of shifting. The control actuator then receives a third command to supply the pressurized oil to the back pressure chamber after the detected gear ratio reaches the predetermined gear ratio.
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