Double clutch system

1. A twin clutch assembly for a motor vehicle drive train that includes a transmission and a drive unit that can be coupled to the transmission by a twin clutch, said twin clutch assembly comprising:

a first, hollow transmission input shaft that includes a free end facing the drive unit and non-rotatably connected to a transmission side output hub of the twin clutch;

a drive side output hub of the twin clutch that is non-rotatably connected with a second transmission input shaft that is rotatably disposed within the first, hollow transmission input shaft;

a clutch cover that is axially disposed between the twin clutch and the drive unit; a drive element axially supported by the clutch cover and non-rotatably connected to the drive unit;

wherein the transmission side output hub is axially supported against movement toward the transmission by an axial support device that is axially biased against the free end of the hollow transmission input shaft and that includes an axially-acting spring carried by the transmission side output hub adjacent a free end of the hollow transmission input shaft that faces the drive unit.

2. A twin clutch assembly in accordance with claim 1 , wherein the spring is elastically deformable.

3. A twin clutch assembly in accordance with claim 1 , wherein the spring is plastically deformable.

4. A twin clutch assembly in accordance with claim 1 , wherein the spring is a wave spring.

5. A twin clutch assembly in accordance with claim 1 , wherein the spring is carried between the free end of the hollow transmission input shaft and a retaining ring carried by the transmission side output hub.

6. A twin clutch assembly in accordance with claim 5 , wherein the retaining ring and the spring engage a groove that is provided on a radially inner surface of the transmission side output hub.

7. A twin clutch assembly in accordance with claim 1 , including an axial bearing axially disposed between the drive unit side output hub and the transmission side output hub.

8. A twin clutch assembly in accordance with claim 1 , including an axial bearing axially disposed between the drive unit side output hub and the drive element.

9. A twin clutch assembly in accordance with claim 1 , including an axial bearing axially disposed between the drive element and the clutch cover.

10. A twin clutch assembly in accordance with claim 1 , wherein the twin clutch includes two multi-disk clutches with outer disk carriers that are non-rotatably connected to the drive unit through the drive element.

11. A twin clutch assembly in accordance with claim 10 , wherein one of the outer disk carriers, in particular a radially outer disk carrier, is non-rotatably connected disengageable to a coupling component on the side of the multi-disk clutches facing the transmission, wherein said coupling component non-rotatably connects the outer disk carriers to one another.

12. A twin clutch assembly in accordance with claim 11 , wherein the coupling component includes a collar on the radial outside, which is angled towards the transmission.

13. A twin clutch assembly in accordance with claim 1 , wherein the twin clutch includes a piston hub, which is used for axial guidance of two pistons and on which a pump drive gear is mounted, which is non-rotatably connected to the drive element, wherein the pump drive gear includes a groove on a radially-outwardly-facing surface for a seal of one of the pistons.

14. A twin clutch assembly in accordance with claim 13 , wherein the pump drive gear is mounted on the piston hub through a press fit, so that at least one radial bore in the piston hub is closed by the pump drive gear.

15. A twin clutch assembly in accordance with claim 1 , wherein the twin clutch includes two multi-disk clutches, each having a respective disk set that includes a respective inner disk carrier and a respective outer disk carrier.

16. A twin clutch assembly in accordance with claim 15 , wherein the twin clutch includes a respective actuation piston associated with the disk sets, wherein the actuation pistons include axial extensions that are of different axial lengths for contacting a respective disk set.

17. A twin clutch assembly in accordance with claim 15 , wherein each of the clutches of the twin clutch includes a respective radially outer disk carrier that includes a respective axially-extending stop, wherein the stops are of different axial extents for contacting respective disk sets.

18. A twin clutch assembly in accordance with claim 15 , wherein the twin clutch includes disk sets having spacer disks carried by one of a respective inner disk carrier and respective outer disk carrier, for filling axial gaps in a respective disk set.

19. A twin clutch assembly for a motor vehicle drive train that includes a transmission and a drive unit that can be coupled to the transmission by a twin clutch, said twin clutch assembly comprising:

a first, hollow transmission input shaft that includes a free end facing the drive unit and non-rotatably connected to a transmission side output hub of the twin clutch;

a drive side output hub of the twin clutch that is non-rotatably connected with a second transmission input shaft that is rotatably disposed within the first, hollow transmission input shaft;

a clutch cover that is axially disposed between the twin clutch and the drive unit; a drive element axially supported by the clutch cover and non-rotatably connected to the drive unit;

wherein the transmission side output hub is axially supported against movement toward the transmission by an axial support device including a retaining ring carried adjacent the free end of the hollow transmission input shaft;

an axial bearing axially disposed between the drive element and the clutch cover and at least one spacer disk disposed between the axial bearing and the clutch cover.

20. A twin clutch assembly in accordance with claim 19 , wherein the retaining ring engages a groove that is provided on a radially inner surface of the transmission side output hub.