Turbine, in particular for an exhaust gas turbocharger, and exhaust gas turbocharger

1. An exhaust gas turbocharger, comprising: a turbine rotor rotatably mounted in a housing, which is associated with a guide apparatus forming a radial inlet channel, wherein the turbine rotor drives a medium in the channel, wherein the guide apparatus comprises a guide vane bearing ring, a plurality of guide vanes radially surrounding the turbine rotor and located in the inlet channel and a guide vane cover ring, wherein the inlet channel is axially delimited by the guide vane bearing ring and the guide vane cover ring, wherein the guide vane bearing ring and the guide vane cover ring are mounted axially and radially moveably relative to each other and to the housing for material relaxation, and wherein the guide apparatus is subjected to axial and radial preload, and wherein a line of flux of the axial preload runs through the guide apparatus substantially parallel to the rotational axis of the turbine rotor.

2. The turbine according to claim 1 , wherein the guide vane bearing ring and the guide vane cover ring each lie in an axial depression of the housing.

3. The turbine according to claim 2 , wherein the axial depression for the guide vane bearing ring is formed in the bearing housing and the axial depression for the guide vane cover ring is formed in the turbine housing.

4. The turbine according to claim 1 , wherein the axial and radial preload on the guide apparatus is simultaneously provided by a single spring.

5. The turbine according to claim 1 , further comprising an axial spacer and wherein the line of flux substantially lies on the same radius as the axial spacer.

6. The turbine according to claim 1 , further comprising: an axial-radial spring element in the form of a pleated ring with radial pleats for simultaneously generating the axial and radial preload.

7. The turbine according to claim 6 , wherein the axial-radial spring element is axially arranged between the guide vane bearing ring and the housing, and the guide vane cover ring and the housing.

8. The turbine according to claim 1 , further comprising an axial spring element for generating the axial preload, the axial spring element is at least one of a helical spring, a coil spring, a disc spring, an O-ring and a C-ring.

9. The turbine according to claim 1 , further comprising: at least one radial spring element for generating the radial preload.

10. The turbine according to claim 9 , wherein the radial spring element is a wavy ring.

11. The turbine according to claim 1 , further comprising: at least one radial-axial spring element for generating the axial and radial preloads.

12. The turbine according to claim 1 , wherein at least one axial spacer is provided between the guide vane bearing ring and the guide vane cover ring.

13. The turbine according to claim 12 , wherein the axial spacer is arranged on at least one of the guide vane bearing ring and the guide vane cover ring.

14. The turbine according to claim 12 , wherein the axial spacer is designed unitarily with at least one of the guide vane bearing ring and the guide vane cover ring.

15. The turbine according to claim 12 wherein at least one axial spring contact region of the guide apparatus substantially lies on the same radius as the axial spacer.

16. The turbine according to claim 11 , wherein the axial spring contact region is arranged aligned with the axial spacer.

17. The turbine according to claim 15 , wherein at least one axial contact region of the housing for the guide apparatus lies substantially on the same radius as at least one of the axial spacer and the axial spring contact region of the guide apparatus.

18. The turbine according to claim 15 wherein the line of flux of the axial preload does not deviate by more than 20% from the radius (r_m), on which the axial spacer lies, in both directions.

19. The turbine according to claim 1 , wherein at least one of the guide apparatus, the guide vane bearing ring and the guide vane cover ring comprise at least one pin connection for at least one of aligning and positioning on the housing.

20. The turbine according to claim 19 , wherein the pin connection comprises at least one pin, which is inserted in a pin reception of the guide apparatus and the housing.

21. The turbine according to claim 20 , wherein at least one pin reception is designed as an elongated hole.

22. The turbine according to claim 21 , wherein the elongated hole in its longitudinal extension is orientated radially or axially.

23. The turbine according to claim 20 wherein the pin is orientated axially or radially.

24. The turbine according to claim 20 wherein at least one pin is formed by one of the axial spacers.

25. An exhaust gas turbocharger, comprising: at least one compressor operationally connected mechanically to at least one turbine rotor, wherein the turbine rotor is rotatably mounted in a housing, which is associated with at least one guide apparatus forming a radial inlet channel, wherein the guide apparatus includes a guide vane bearing ring, a plurality of guide vanes radially surrounding the turbine rotor and located in the inlet channel and a guide vane cover ring, wherein the inlet channel is axially delimited by the guide vane bearing ring and the guide vane cover ring, wherein the guide vane bearing ring and the guide vane cover ring are moveably mounted axially and radially relative to each other and to the housing, and wherein the guide apparatus is subjected to an axial and radial preload, and wherein a line of axial preload flux runs through the guide apparatus substantially parallel to the rotational axis of the turbine rotor.

26. The turbine according to claim 1 , wherein the guide vane bearing ring contacts the housing.