Automatic transmission

摘要

An automatic transmission includes an input member, a planetary gear mechanism, a plurality of engagement mechanisms, an output member, a control unit, and a switching mechanism. The control unit is able to perform a backward preparation mode (step 3) which enables the rpm of an element fixed by the switching mechanism to be predetermined rpm or less by bringing the engagement mechanism into a connected state or a fixed state when the shift position is switched from a forward range to a backward range (step 1). The control unit switches the switching mechanism from a reverse-rotation preventing state to the fixed state (step 7) after the rpm of the element becomes the predetermined rpm or less (step 5) by performing the backward preparation mode.

主权项

1. An automatic transmission comprising:
a housing; a drive source; an input member arranged in the housing to which motive power of the drive source is transmitted; a planetary gear mechanism comprising a plurality of elements rotatable in the housing; a plurality of engagement mechanisms configured to switch between a connected state wherein at least one of the plurality of elements is connected to another of the plurality of elements and a first fixed state wherein the at least one or another of the plurality of elements is fixed to the housing; an output member; and a control unit configured to control the plurality of engagement mechanisms, the automatic transmission configured to shift rotation of the input member in multiple stages and freely output the rotation from the output member and further comprising: a switching mechanism configured to switch between a reverse-rotation preventing state where a normal rotation by which a vehicle runs in a forward direction is allowed and a reverse rotation by which the vehicle runs in a backward direction is prevented with respect to one of the plurality of elements and a second fixed state where the one of the plurality of elements is fixed to the housing, wherein: the control unit is configured to bring the switching mechanism into the reverse-rotation preventing state when a shift position is in a forward range and bring the switching mechanism into the second fixed state when the shift position is in a backward range; the control unit is configured to perform a backward preparation mode which enables an rpm of the one of the plurality of elements fixed by the switching mechanism to be a predetermined rpm or less by bringing the one of a plurality of engagement mechanisms into the connected state or the first fixed state when the shift position is switched from the forward range to the backward range; and the control unit is configured to switch the switching mechanism from the reverse-rotation preventing state to the second fixed state after the rpm of the one of the plurality of elements becomes the predetermined rpm or less by performing the backward preparation mode.