Valve

1. A hot gas exhaust recirculation valve comprising:

a housing containing a duct for conducting gases;

a drive chamber, which does not conduct gases;

a valve stem, which is mounted in the housing such that said valve stem can be displaced in a longitudinal direction thereof during valve-operation and which extends from the drive chamber into the duct, wherein a first end of said valve stem is situated in the drive chamber being coupleable to a drive device;

a closing body fastened to a second end of said valve stem and situated in the duct, said closing body being movable by the valve stem along the longitudinal direction of the valve stem during valve-operation and having a closed position, in which the closing body separates an upstream section of the duct from a downstream section of the duct;

wherein a sealing ring surrounds the valve stem and is arranged between the duct and the drive chamber;

wherein the valve stem is supported within two bearing bushings that are spaced apart from each other, between which the sealing ring is arranged.

2. The hot gas exhaust recirculation valve according to claim 1 , wherein the two bearing bushings consist of different materials.

3. The hot gas exhaust recirculation valve according to claim 2 , wherein the bearing bushing closer to the duct consists of high-grade steel.

4. The hot gas exhaust recirculation valve according to claim 2 , wherein the bearing bushing further away from the duct consists of non-ferrous metal.

5. The hot gas exhaust recirculation valve according to claim 1 , wherein an outer diameter of the sealing ring corresponds to at least an outer diameter of one of the two bearing bushings.

6. The hot gas exhaust recirculation valve according to claim 1 , wherein a free annular space surrounds the valve stem and is arranged between the bearing bushing closer to the duct and the sealing ring.

7. The hot gas exhaust recirculation valve according to claim 1 , wherein the valve stem consists of high-grade steel.

8. The hot gas exhaust recirculation valve according to claim 1 , wherein a protective sleeve adjoins the bearing bushing closer to the duct, wherein the protective sleeve extends from said bearing bushing in the direction of the closing body and surrounds the valve stem at a distance.

9. The hot gas exhaust recirculation valve according to claim 1 , wherein a ratio of an effective bearing length, which is defined as a distance between outer edges of the two bearing bushings, and a distance of a radial force exerted by the drive device from the bearing bushing further away from the duct is between 1.2:1 and 1.8:1.

10. The hot gas exhaust recirculation valve according to claim 1 , wherein the valve stem and the closing body move together in the longitudinal direction during valve-operation.

11. The hot gas exhaust recirculation valve according to claim 1 , wherein the two bearing bushings are configured to arrange the valve stem allowing the valve stem to only be displaced in the longitudinal direction during valve-operation.

12. A hot gas exhaust recirculation valve comprising:

a housing containing a duct for conducting gases;

a drive chamber, which does not conduct gases;

a valve stem movably mounted in the housing displaceable during valve-operation in a longitudinal direction thereof, the valve stem extending from the drive chamber into the duct, wherein a first end of said valve stem is situated in the drive chamber and is coupleable to a drive device;

a closing body fastened to a second end of said valve stem and situated in the duct, said closing body being movable by the valve stem along the longitudinal direction of the valve stem during valve-operation and having a closed position in which the closing body separates an upstream section of the duct from a downstream section of the duct;

a sealing ring surrounding the valve stem, the sealing ring arranged between the duct and the drive chamber;

wherein the valve stem is supported within two bearing bushings that are spaced apart from each other, between which the sealing ring is arranged;

wherein the two bearing bushings consist of different materials where the bearing bushing closer to the duct consists of high-grade steel and the bearing bushing further away from the duct consists of non-ferrous metal.

13. The hot gas exhaust recirculation valve according to claim 12 , including a free annular space surrounding the valve stem, where the free annular space is arranged between the bearing bushing closer to the duct and the sealing ring.

14. The hot gas exhaust recirculation valve according to claim 13 , wherein the valve stem consists of high-grade steel.

15. The hot gas exhaust recirculation valve according to claim 14 , including a protective sleeve adjoining the bearing bushing closer to the duct, wherein the protective sleeve extends from said bearing bushing in the direction of the closing body and surrounds the valve stem at a distance.

16. The hot gas exhaust recirculation valve according to claim 15 , wherein a ratio of an effective bearing length, which is defined as a distance between outer edges of the two bearing bushings, and a distance of a radial force exerted by the drive device from the bearing bushing further away from the duct is between 1.2:1 and 1.8:1.

17. The hot gas exhaust recirculation valve according to claim 12 , wherein the valve stem and the closing body move together in the longitudinal direction during valve-operation.

18. The hot gas exhaust recirculation valve according to claim 12 , wherein the two bearing bushings are configured to arrange the valve stem allowing the valve stem to only be displaced in the longitudinal direction during valve-operation.