Automatic transmission for a vehicle

1. A multi-speed automatic transmission comprising:

a housing;

a transmission input shaft; and

a plurality of clutches, wherein different combinations of a predetermined number of clutches of the plurality of clutches generate respective different gear ratios corresponding to respective forward or rearward speeds of the automatic transmission, the plurality of clutches including:

a first clutch comprising a multi-plate clutch portion and a selectable one way clutch portion, wherein the selectable one way clutch is engaged for selectively generating one forward speed and one rearward speed of the automatic transmission,

wherein the selectable one way clutch portion is movable between a forward torque holding mode configured to transfer torque in a first rotational direction but not in an opposite second rotational direction, and a rearward torque holding mode configured to transfer torque in the second rotational direction but not in the first rotational direction, and

wherein the selectable one way clutch portion is operated in the forward torque holding mode in nine forward speeds of the automatic transmission, the selectable one way clutch portion is operated in the rearward torque holding mode in the one rearward speed of the automatic transmission, and the multi-plate clutch portion is selectively engaged to transfer torque in three of the nine forward speeds, wherein the nine forward speeds includes the one forward speed.

2. The automatic transmission of claim 1 , wherein the selectable one way clutch portion includes an input driving member coupled to a ring gear and an output driven member coupled to the transmission housing.

3. The automatic transmission of claim 1 , further comprising a controller configured to move the multi-plate clutch portion between an engaged state and a disengaged state.

4. The automatic transmission of claim 1 , wherein the multi-plate clutch portion includes a retainer and a clutch pack.

5. The automatic transmission of claim 4 , wherein the retainer is grounded to the housing and the clutch pack includes alternating first and second friction discs.

6. The automatic transmission of claim 5 , wherein the first friction discs are coupled to a ring gear and configured to rotate therewith, and the second friction discs are grounded to the transmission housing through the retainer.

7. The automatic transmission of claim 6 , wherein the first friction discs comprise only two first friction discs.

8. A nine-speed automatic transmission comprising:

a housing;

a transmission input shaft;

a first clutch coupled to the transmission input shaft;

a second clutch;

a third clutch;

a fourth clutch comprising a multi-plate clutch portion and a selectable one way clutch portion, wherein the selectable one way clutch portion is engaged to selectively generate one forward speed and one rearward speed of the automatic transmission;

a fifth clutch; and

a sixth clutch,

wherein the selectable one way clutch portion is movable between a forward torque holding mode configured to transfer torque in a first rotational direction but not in an opposite second rotational direction, and a rearward torque holding mode configured to transfer torque in the second rotational direction but not in the first rotational direction,

wherein the selectable one way clutch portion is operated in the forward torque holding mode in nine forward speeds of the automatic transmission, the selectable one way clutch portion is operated in the rearward torque holding mode in the one rearward speed of the automatic transmission, and the multi-plate clutch portion is engaged to selectively transfer torque in three of the nine forward speeds, wherein the nine forward speeds includes the one forward speed.

9. The automatic transmission of claim 8 , wherein the selectable one way clutch portion transfers torque in one of the nine forward speeds and overruns in eight of the nine forward speeds.

10. The automatic transmission of claim 9 , wherein the selectable one way clutch portion transfers torque in a first gear and the one rearward speed of the automatic transmission, and the multi-plate clutch portion transfers torque in a seventh, eighth, and ninth gear of the automatic transmission.

11. A multi-speed automatic transmission comprising:

a housing;

a transmission input shaft; and

a plurality of clutches, wherein different combinations of a predetermined number of clutches of the plurality of clutches generate respective different gear ratios corresponding to respective forward or rearward speeds of the automatic transmission, the plurality of clutches including:

a first clutch comprising a multi-plate clutch portion and a selectable one way clutch portion, wherein the selectable one way clutch is engaged for selectively generating one forward speed and one rearward speed of the automatic transmission,

wherein the multi-plate clutch portion includes a retainer and a clutch pack,

wherein the retainer is grounded to the housing and the clutch pack includes alternating first and second friction discs, and

wherein the first friction discs are coupled to a ring gear and configured to rotate therewith, and the second friction discs are grounded to the transmission housing through the retainer.