X-tube and corresponding exhaust system

1. An X-tube for an at least partly double-flow exhaust system of a motor vehicle internal combustion engine, the X-tube comprising:

a housing comprising two half shells providing two inlet openings on an inlet side and two outlet openings on an outlet side;

an interior space enclosed by said housing and to which said openings are connected in a communicating manner;

a bottom comprising a separate component in relation to the two half shells, said bottom dividing the interior space into two ducts, which are each connected to a respective one of said inlet openings and to a respective one of said outlet openings, each in a communicating manner, wherein said bottom is made permeable to airborne sound and connects said two ducts to one another in an airborne sound-transmitting manner.

2. An X-tube in accordance with claim 1 , wherein said half shells each have, between said ducts, a mounting groove into which longitudinal ends of said bottom are inserted.

3. An X-tube in accordance with claim 2 , wherein said half shells each have, between said ducts, two inwardly projecting longitudinal beads, which extend in parallel to one another and form the respective mounting grooves in the interior space.

4. An X-tube in accordance with claim 1 , wherein the position of said bottom is fixed in said housing by bracing said bottom with said half shells or by a welded connection of said bottom to at least one of the half shells.

5. An X-tube in accordance with claim 1 , wherein said bottom extends in a plane that extends in parallel to a principal directions of flow prevailing in said two ducts, said principal directions of flow being in parallel to each other, and said plane extends at right angles to a plane of separation, in which said half shells are attached to one another.

6. An X-tube in accordance with claim 1 , wherein on a side facing one of said ducts, said bottom has a collar extending circumferentially on an edge and projecting from said duct.

7. An X-tube in accordance with claim 6 , wherein said collar is flattened on the inlet side and on the outlet side.

8. An X-tube in accordance with claim 7 , wherein said bottom has an oval shape with a rectangular middle section and two semicircular end sections.

9. An X-tube in accordance with claims 8 , wherein the flattened areas are formed each exclusively in the end sections.

10. An X-tube in accordance with claim 1 , wherein said bottom is mirror symmetrical in relation to a plane of separation, in which the half shells are attached to one another.

11. An X-tube in accordance with claim 1 , wherein said two half shells are designed as identical parts.

12. An X-tube in accordance with claim 1 , wherein:

said two inlet sections, which connect one of the inlet openings each to one of said ducts, are formed on said housing; and

said two outlet sections, which connect one of the outlet openings each to one of said ducts are formed on said housing.

13. An X-tube in accordance with claim 1 , wherein outside said interior space, said half shells, on the inlet side and on the outlet side, each have a connecting web which are flatly in contact with one another.

14. An exhaust system for a motor vehicle internal combustion engine, the system comprising: two exhaust pipes through which flow can take place in parallel; and an X-tube coupling said two exhaust pipes with one another, said X-tube comprising:

a housing comprising two half shells providing two inlet openings on an inlet side and two outlet openings on an outlet side;

an interior space enclosed by said housing and to which said openings are connected in a communicating manner;

a bottom comprising a separate component in relation to the two half shells, said bottom dividing the interior space into two ducts, which are each connected to a respective one of said inlet openings and to a respective one of said outlet openings, each in a communicating manner, wherein said bottom is made permeable to airborne sound and connects said two ducts to one another in an airborne sound-transmitting manner.

15. A system in accordance with claim 14 , wherein said half shells each have, between the ducts, a mounting groove into which longitudinal ends of said bottom are inserted.

16. A system in accordance with claim 15 , wherein the half shells each have, between the ducts, two inwardly projecting longitudinal beads, which extend in parallel to one another and form the respective mounting grooves in the interior space.

17. A system in accordance with claim 14 , wherein said bottom extends in a plane that extends in parallel to a principal directions of flow prevailing in said two ducts, said principal directions of flow being in parallel to each other, and said plane extends at right angles to a plane of separation, in which said half shells are attached to one another.

18. A system in accordance with claim 14 , wherein:

on a side facing one of said ducts, said bottom has a collar extending circumferentially on an edge and projecting from said duct

said collar is flattened on the inlet side and on the outlet side;

said bottom has an oval shape with a rectangular middle section and two semicircular end sections; and

the flattened areas are formed each exclusively in the end sections.

19. A system in accordance with claim 14 , wherein

said bottom is mirror symmetrical in relation to a plane of separation, in which the half shells are attached to one another; and

said two half shells are designed as identical parts.

20. A system in accordance with claim 14 , wherein:

said two inlet sections, which connect one of the inlet openings each to one of said ducts, are formed on said housing; and

said two outlet sections, which connect one of the outlet openings each to one of said ducts are formed on said housing.