Nozzle ring for a turbocharger

1. A nozzle ring for a radial turbine, the nozzle ring comprising:

a rotationally symmetrical, disk-shaped main body with a central opening for receiving a shaft, wherein the main body is configured to form a heat shield between a bearing space of a bearing housing and a turbine space, with one or more recesses in a bearing housing side of the main body forming one or more air-filled insulation spaces, when the nozzle ring is installed;

guide blades integrally formed with the main body and free floating at one end forming a single piece structure, wherein the guide blades are arranged circumferentially in a radially outer region of the main body and each extend from the main body in an axial direction, and wherein the guide blades are configured to direct exhaust gases onto rotor blades of a turbine wheel; and

a fastening flange arranged in a radially inner region of the main body, wherein the fastening flange has a contact surface configured for support on a corresponding contact surface of the bearing housing; wherein the fastening flange comprises one or more bores arranged circumferentially and configured to receive one or more fasteners in order to install the nozzle ring on the bearing housing.

2. The nozzle ring of claim 1 , wherein the fastening flange is integrally formed with the main body.

3. The nozzle ring of claim 1 , wherein the one or more recesses comprise ribs which extend in a radial direction.

4. The nozzle ring of claim 3 , wherein the one or more bores are arranged in the fastening flange on a first virtual circular line with a first radius around the central opening, and wherein the guide blades are arranged on a second virtual circular line with a second radius around the central opening, wherein the second radius is at least 1.5 times larger than the first radius.

5. The nozzle ring of claim 3 , wherein a plurality of bores are arranged in the fastening flange at regular angular intervals around the central opening.

6. The nozzle ring of claim 1 , wherein the nozzle ring is configured such that, when the nozzle ring is installed, heat causes the nozzle ring to become at least one of: axially clamped between the bearing housing and a turbine housing defining the turbine space, radially clamped in the bearing housing, and radially clamped in the turbine housing.

7. An exhaust-gas turbocharger comprising:

a shaft mounted in a bearing housing;

a turbine wheel with rotor blades arranged on the shaft;

a turbine housing having an inflow channel for exhaust gases, the inflow channel being positioned in the turbine housing upstream of the turbine wheel; and

a nozzle ring held axially between the bearing housing and the turbine housing, wherein the nozzle ring comprises:

a rotationally symmetrical, disk-shaped main body with a central opening receiving the shaft, wherein the main body forms a heat shield between a bearing space of the bearing housing and a turbine space of the turbine housing, with one or more recesses in a bearing housing side of the main body forming one or more air-filled insulation spaces;

guide blades integrally formed with the main body and free floating at one end forming a single piece structure, wherein the guide blades are arranged circumferen-tially in a radially outer region of the main body and each extend from the main body in an axial direction, and wherein the guide blades are configured to direct exhaust gases onto the rotor blades of the turbine wheel; and

a fastening flange arranged in a radially inner region of the main body, wherein the fastening flange is fastened to the bearing housing by one or more fasteners.

8. The exhaust-gas turbocharger of claim 7 , wherein the one or more fasteners are screws, the nozzle ring being screwed to the bearing housing.

9. The exhaust-gas turbocharger of claim 7 , wherein the nozzle ring is axially braced in a manner of a plate spring between the bearing housing and the turbine housing.

10. The exhaust-gas turbocharger of claim 7 , wherein one or more rotation prevention means are provided between the nozzle ring and at least one of the bearing housing or the turbine housing.

11. The exhaust-gas turbocharger of claim 7 , wherein the nozzle ring is configured such that heat causes the nozzle ring to become at least one of: axially clamped between the bearing housing and the turbine housing, radially clamped in the bearing housing, and radially clamped in the turbine housing.

12. The exhaust-gas turbocharger of claim 7 , wherein the fastening flange is integrally formed with the main body.

13. The exhaust-gas turbocharger of claim 7 , wherein the fastening flange comprises one or more bores arranged circumferentially and configured to receive the one or more fasteners.

14. The exhaust-gas turbocharger of claim 13 , wherein the one or more recesses comprise ribs which extend in a radial direction.

15. The exhaust-gas turbocharger of claim 13 , wherein the one or more bores are arranged in the fastening flange on a first virtual circular line with a first radius around the central opening, and wherein the guide blades are arranged on a second virtual circular line with a second radius around the central opening, wherein the second radius is at least 1.5 times larger than the first radius.

16. The exhaust-gas turbocharger of claim 13 , wherein the one or more bores are arranged in the fastening flange at regular angular intervals around the central opening.

17. The nozzle ring of claim 6 , wherein the one or more recesses comprise ribs which extend in a radial direction.