| 摘要 |
An automatic transmission includes an input member, a planetary gear mechanism, a plurality of engagement mechanisms, an output member, a shift position detector, an input rotational speed detector, a controller, and a switching mechanism. The controller is configured to set the switching mechanism in a reverse-rotation prevention state when a shift position is set in a forward movement range and configured to set the switching mechanism in a fixed state when the shift position is set in a backward movement range. The controller is configured to control the plurality of engagement mechanisms so that the input member is capable of rotating and rotation of the output member is prevented in a case in which a vehicle is moving backward, the shift position is switched from the backward movement range to the forward movement range, and a vehicle speed is greater than or equal to a first predetermined speed. |
| 主权项 |
1. An automatic transmission comprising an input member that is disposed in a housing and that receives power of a driving source via a torque converter, a planetary gear mechanism including a plurality of elements that are rotatable in the housing, a plurality of engagement mechanisms that are each switchable to a connection state in which the plurality of engagement elements are connected to each other or to a fixed state in which the plurality of engagement elements are fixed to the housing, an output member, a shift position detecting unit that detects a shift position, an input rotational speed detecting unit that detects a rotational speed of the input member; and a controller that receives information regarding the detected rotational speed from the input rotational speed detecting unit and information regarding the shift position from the shift position detecting unit, and that controls the engagement mechanisms, wherein the rotational speed of the input member is changed into a plurality of gear speeds and rotation of the input member is freely output to the output member and the automatic transmission further comprises a switching mechanism that is switchable between a reverse-rotation prevention state and a second fixed state, the reverse-rotation prevention state being a first state in which forward rotation of one of the plurality of elements is allowed and reverse rotation of the one of the plurality of elements is prevented, the forward rotation being in a rotation direction when a vehicle moves forward, the reverse rotation being in a rotation direction when the vehicle moves backward, the second fixed state being a second state in which the one of the plurality of elements is fixed to the housing, wherein the controller sets the switching mechanism in the reverse-rotation prevention state when the shift position is set in a forward movement range and sets the switching mechanism in the second fixed state when the shift position is set in a backward movement range, and wherein, when the vehicle is moving backward and the shift position is switched from the backward movement range to the forward movement range, if a vehicle speed is greater than or equal to a first predetermined speed, the controller controls the engagement mechanisms so that the input member is capable of rotating freely and rotation of the output member is prevented. |
