AUTOMATIC TRANSMISSION

摘要

An automatic transmission includes an input member, a planetary gear set, a plurality of engagement mechanisms, an output member, a shift position detecting unit, an input rotational speed detecting unit, a control unit, and a switching mechanism. When a shift position is changed from a forward drive range to a reverse drive range, the control unit performs a reverse preparation mode in which a rotational speed of an element to be fixed by the switching mechanism is lower than or equal to a predetermined speed by setting an engagement mechanism in one of a connection mode and a fixed mode. Upon performing the reverse preparation mode, the control unit engages the engagement mechanism that connects the element fixed by the switching mechanism to the input member and, thereafter, engages the engagement mechanism that makes the rotational speed of the input member lower than or equal to the predetermined speed.

主权项

1. An automatic transmission comprising:
an input member disposed in a housing to receive power transferred from a drive source; a planetary gear set including a plurality of elements rotatable in the housing; a plurality of engagement mechanisms each switchable between a connection mode in which the elements are connected to each other and a fixed mode in which one of the elements is fixed to the housing; an output member; a shift position detecting unit configured to detect a shift position; an input rotational speed detecting unit configured to detect the rotational speed of the input member; a control unit configured to receive information regarding the rotational speed detected by the input rotational speed detecting unit and information regarding the shift position detected by the shift position detecting unit and control the engagement mechanisms, the rotational speed of the input member being changed into one of a plurality of speeds, and the rotation of the input member being output from the output member; and a switching mechanism configured to switch between a reverse rotation prevention mode in which forward rotation of one of the elements representing rotation in a direction to move a vehicle forward is allowed and reverse rotation of the element representing rotation in a direction to move the vehicle backward is prevented and a fixed mode in which the element is fixed to the housing, wherein the control unit sets the switching mechanism in the reverse rotation prevention mode when a shift position is set to a forward drive range and sets the switching mechanism in the fixed mode when the shift position is set to a reverse drive range, wherein when the shift position is changed from the forward drive range to the reverse drive range, the control unit performs a reverse preparation mode in which the rotational speed of the element to be fixed by the switching mechanism is lower than or equal to a predetermined speed by setting the engagement mechanism in one of the connection mode and the fixed mode, and wherein upon performing the reverse preparation mode, the control unit engages the engagement mechanism that connects the element fixed by the switching mechanism to the input member and, thereafter, engages the engagement mechanism that makes the rotational speed of the input member lower than or equal to the predetermined speed.